Schizophrenia and bipolar disorder are debilitating psychiatric disorders with partially shared symptomatology including psychotic symptoms and cognitive impairment. Aberrant levels of microglia and neurodegenerative cerebrospinal fluid (CSF) markers have previously been found in schizophrenia and bipolar disorder. We aimed to analyze familial and environmental influences on these CSF markers and their relation to psychiatric symptoms and cognitive ability. CSF was collected from 17 complete twin pairs, nine monozygotic and eight dizygotic, and from one twin sibling. Two pairs were concordant for schizophrenia, and 11 pairs discordant for schizophrenia, schizoaffective disorder or bipolar disorder, and four pairs were not affected by psychotic disorders. Markers of microglia activation , markers of β-amyloid metabolism , soluble amyloid precursor proteins (sAPP-α and sAPP-β), total tau (T-tau), phosphorylated tau (P-tau), and CSF/serum albumin ratio were measured in CSF using immunoassays. Heritability of the CSF markers was estimated, and associations to psychiatric and cognitive measurements were analyzed. Heritability estimates of the microglia markers were moderate, whereas several neurodegenerative markers showed high heritability. In contrast, AβX-42, Aβ1-42, P-tau and CSF/serum albumin ratio were influenced by dominant genetic variation. Higher sCD14 levels were found in twins with schizophrenia or bipolar disorder compared to their not affected co-twins, and higher sCD14-levels were associated with psychotic symptoms. The study provides support for a significant role of sCD14 in psychotic disorders and a possible role of microglia activation in psychosis.The online version of this article (doi:10.1007/s00406-016-0759-5) contains supplementary material, which is available to authorized users. Bipolar disorder and schizophrenia are serious psychotic disorders associated with severe symptomatology and functional impairment. The lifetime prevalence for bipolar spectrum disorders is estimated at 2.4%  and at 0Evidence from epidemiological studies –8 as welAlthough such studies—using peripheral blood as substrate—provide evidence for systemic inflammation, they cannot readily be extrapolated to immunological activity in the brain. To study neuroinflammation and microglial activation, cerebrospinal fluid (CSF) is a more appropriate sampling substrate as it more closely reflects the brain biochemistry . Our resCognitive impairment is a core symptom of schizophrenia  and is aAn important limitation with these prior studies on CSF microglia and neurodegenerative markers in bipolar disorder is the cross-sectional case–control design where it is not possible to separate genetic contributions (trait) from the effect of the disease (state). One possible solution is to study twins, which may allow disentangling genetic, shared environmental, and unique environmental influences on CSF markers. We have previously used a twin model to examine the association between microscopic structures in CSF and psychosis in twins with schizophrenia and bipolar disorder , 33.In the present study, we investigated CSF markers in 17 complete twin pairs with schizophrenia or bipolar disorder and in one twin sibling. We analyzed three immune-related markers , six amyloid-related markers , along with T-tau and P-tau. The aim was to estimate the heritability of the CSF markers and to analyze the genetic and environmental influences of the analyzed markers in a co-twin control design, as well as to study associations between psychotic symptoms in relation to the CSF markers. We also examined the CSF markers in relationship to other personality and cognitive variables in a set of exploratory analyses.The twin pairs were recruited from a nationwide study of Swedish-born, same-sex twins with schizophrenia, schizoaffective disorder, bipolar disorder, and healthy control pairs . All stuhttp://www.socialstyrelsen.se) covering the period 1973–2009.All study participants first completed screening forms of The Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I)  and AxisThe zygosity of the twins, MZ or DZ, was validated using a panel of 47 highly multiplexed single-nucleotide polymorphisms (SNP)  that pron = 6), schizoaffective disorder (n = 2), bipolar disorder type I (n = 4), or bipolar disorder type II (n = 3), 12 unaffected co-twins, and eight healthy twin controls. In the overall statistical analyses, we collapsed the diagnoses schizophrenia, schizoaffective disorder, bipolar disorder I and II into one category designated ‘psychotic disorder.’ In secondary analyses, we collapsed the diagnoses schizophrenia and schizoaffective disorder into one category designated ‘schizophrenia’ and bipolar disorder type 1 and 2 into one category designated ‘bipolar disorder.’ Nine out of 15 probands were prescribed antipsychotic medication of the following types: haloperidol, levomepromazine, olanzapine, perphenazine, quetiapine and risperidone.There were in total 15 probands with either schizophrenia  and the white blood cell count (WBC) were measured. Height and weight were recorded on the same day as blood and CSF sampling and used for calculation of the body mass index (BMI) as a heuristic proxy for body fat of the participants.Albumin levels in CSF and serum were measured at the Clinical Neurochemistry Laboratory in Mölndal, Sweden, by immunonephelometry on a Beckman Immage Immunochemistry system . The method was accredited by the Swedish Board for Accreditation and Conformity Assessment (SWEDAC). Experienced and board-certified laboratory technicians who were blinded to clinical information performed all measurements. Intra- and inter-assay coefficients of variation were below 10%. To assess the blood CSF barrier function, the ratio between albumin concentration in CSF (mg/L) and serum (g/L) was calculated.® Human MCP-1 Ultra-Sensitive Kit, MSD® sAPP-α/sAPP-β Multiplex Assay, and MSD ® Human/Rodent (4G8) Abeta-Triplex Assay, respectively, as described by the manufacturer . CSF concentrations of P-tau, T-tau, and Aβ1-42 were measured simultaneously by the Luminex xMAP technology using the Inno-Bia AlzBio3 kit . The MSD-derived Aβ concentrations were derived using a detection antibody against the mid-domain of the Aβ proteins, whereas we also measured Aβ-42 using the AlzBio3 kit. This kit includes a neo-epitope-specific antibody against the first amino acids of Aβ. For this reason, we denote MSD-derived Aβ concentrations AβX-38, AβX-40 and AβX-42 and AlzBio3-derived Aβ concentrations Aβ1-42 throughout the manuscript. sCD14 and YKL-40 were determined by Human sCD14 quantikine ELISA kit and Human chitinase-3 quantikine ELISA kit, respectively . All CSF analyses were performed in one round of analyses using one batch of reagents by board-certified laboratory technicians who were blinded to clinical information.The CSF concentrations of MCP-1, sAPP-α and sAPP-β, and AβX-38, AβX-40, and AβX-42 were determined using the MSDχ2 statistic, the root-mean-square error of approximation (RMSEA), and the Akaike information criterion (AIC). The AIC is a relative measure of fit  compared to the MZ pairs , Fig. r(8) = 0.52, p = 0.18] nor in the MZ pairs . These results are not in accordance with a causal hypothesis where higher CSF/serum albumin ratio causes higher levels of sCD14 or YKL-40.In this study and in a previous report, associations were identified between CSF/serum albumin ratio and the microglia markers sCD14 and YKL-40 . The comt = 3.28, p = 0.0066).The traditional proband-co-twin control analysis was not the most suitable statistical model due to a limited number of control pairs in our sample. As expected, given the results from the co-twin control analysis, significantly higher levels of sCD14 were found in the probands compared to the co-twins  gene [APOE gene and vascular regulation in schizophrenia [APOE gene to be a risk factor in schizophrenia [A previous study demonstrated lower CSF Aβ-42 levels in carriers of the ε4 allele of the apolipoprotein E (OE) gene , but recOE) gene . Moreoveophrenia , but a rophrenia . In the Finally, we screened the results from the psychometric scales and cognitive ability against the 11 CSF markers. We found an association between sCD14 and impulsivity, in line with some previous work suggesting a relationship between immune functioning and impulsivity , 64. In Strengths of this study include the unique collection of CSF from twins concordant and discordant for schizophrenia or bipolar disorder. The participants were thoroughly phenotyped and reexamined in conjunction to lumbar puncture. However, it is challenging to recruit twin pairs concordant and discordant for psychotic disorder volunteering for a spinal tap. The sample size of this study is therefore limited. We performed several tests and the obtained results would not withstand correction for multiple testing. In balancing the risk for type I and type II errors, we opted for presenting the results without correction for multiple testing. This means that there is a risk for false-positive findings, and results should be regarded as preliminary pending future replications in larger twin samples.In summary, in a unique sample of twins with and without psychotic disorders, we demonstrated for the first time higher CSF sCD14 levels in twins with a diagnosis of schizophrenia or bipolar disorder compared to unaffected co-twins. This difference is interpreted as partly attributable to environmental factors such as inflammation within the CNS. In consonance with this, higher CSF sCD14 levels were associated with psychotic symptoms and paranoid and schizotypal personality traits, supporting a dimensional approach, independent of established diagnoses. Finally our study indicates moderate heritability estimates of the microglia CSF markers, high heritability estimates of T-tau, and the amyloid metabolism markers, whereas the markers of Alzheimer’s disease  were affected by dominant genetic influences. The study provides further evidence to the hypothesis of CNS inflammation in psychotic disorders and a possible significant role of sCD14.Supplementary material 1 (DOCX 26 kb)Below is the link to the electronic supplementary material.


Male BRCA mutation carriers are at risk for an early onset aggressive prostate cancer. No data exist on the association of testosterone levels among these patients. We aimed to analyze testosterone and associated hormonal levels among male BRCA carriers and non-carriers.Overall 87 male carriers and 43 non-carriers aged 40-70 were prospectively enrolled. Clinical data were collected and all patients were tested for total testosterone (TT), prostate specific antigen (PSA), follicle stimulating hormone (FSH), luteinizing hormone (LH), free androgen index (FAI), sex hormone binding globulin (SHBG) and prolactin. Multivariate linear regression analysis was performed to predict TT levels.The median age, mean BMI, comorbidities, PSA, FSH, LH and SHBG levels in both groups were similar. However, mean TT and FAI were higher in the carriers , while prolactin was significantly lower. Multivariate analysis demonstrated that while BMI was inversely correlated to TT levels in both groups, LH was a predictor only in non-carriers.Carriers have higher TT and FAI levels and lower prolactin levels; but LH does not predict their TT levels. Further research in a larger cohort of BRCA carriers with and without prostate cancer should be performed. Breast Cancer susceptibility genes 1&2 (BRCA1&2) are involved in DNA repair and cell cycling , 4.Several studies have reported that the risk of PCa is higher among male carriers of BRCA1& 2 mutations -8. The rThere is a large proportion of BRCA carriers among Ashkenazi Jews compared to other populations in the world, 2.6% compared to 0.2%, respectively . In our Prostate growth is androgen dependent  in malesThere are published reports demonstrating an association between PCa and TT , but itsThere are no published data to date, on the association between TT levels, PCa and BRCA mutation carriers. Therefore, our aim in this study was to characterize TT and additional hormonal levels in male BRCA carriers and try to ascertain if any difference exists in comparison to a group of healthy males without BRCA mutations.Overall 87 male carriers and 43 non-carriers were enrolled in our study and both groups were age matched. Only 29 patients (22.33%) refused to participate in our study. A third of the carriers were BRCA2 carriers and the rest were BRCA1. As shown in Table The blood tests shown in Table PCa is the second most common cancer in men worldwide and sixth most common cause of death . Men witThe results of our hypothesis generating study show that among men between the ages of 40-70, BRCA carriers had a significantly higher plasma levels of TT and FAI while their prolactin levels were lower compared to controls. Furthermore, univariate and MLRA demonstrated that TT level was not correlated to LH levels among BRCA carriers.This is not a new concept, as other reports have shown that TT secretion maybe independent of LH in certain circumstances. Patients with CRPC have been shown to have an increase in a series of genes mediating androgen synthesis and catabolism in the prostate . This isEven in healthy men it has been demonstrated that LH and TT concentrations show significant seasonal variations, and that LH and TT are not in phase, differing in their secretory zenith by about 6 months, thus excluding a hierarchical pivotal role of LH in regulating seasonal variations of TT levels . It was + channel [Additionally, several experiments performed in animal models have shown an LH independent pathway for TT secretion. These include a macrophage derived factor stimulating TT production by Leydig cells , physiol channel  and GNRH channel .The exact mechanism leading to aggressive PCa in BRCA carriers is unknown. Taylor et al , recentlSumming up the last paragraphs, it seems that BRCA carriers with PCa undergo mutations culminating in a very early status of CRPC, where TT has been shown to be secreted in an LH independent manner. We therefore, hypothesized that BRCA carriers, even those without PCa, might have similar mutations causing higher TT to be secreted in an LH independent manner in accordance with our results. The higher TT levels, could help explain their more aggressive early onset PCa. In a meta-analysis of hormonal predictors of PCa, Shaneyfelt et al. have shown that even healthy men who have TT levels in the upper quartile of the population distribution, are 2.34 times more likely to develop PCa . We therThere are numerous evidence suggesting a link between hormonal regulation and cancer among BRCA carriers. First, the most common malignancies in BRCA carriers are breast, ovary and prostate, which are all hormonal mediated organs -4. SeconThis is the first prospective study to our knowledge that attempts to study the implication of male BRCA mutations on TT and various other hormones. Although the involved mechanisms are still unknown, this pilot study does reveal some new insights. The higher TT and FAI might possibly be the hormonal linking factor to the aggressive PCa seen in BRCA carriers. Limitations of this study include its small sample size, lack of validation of hormonal levels over time and no comparison to carriers who developed PCa. We are also limited by the fact that Dihydrotestosterone (DHT) levels were not measured, which could have given us additional information. However, the formation of DHT from TT by the enzyme 5-alpha reductase is a process that occurs only in tissues  and does not occur in the blood stream. Therefore, blood level measurements of DHT often lead to equivocal or even false-negative results , 38, renTo conclude, in this hypothesis generating study BRCA carriers have been shown to have a significantly higher TT and FAI levels compared to healthy age matched men. It also demonstrates that in contradiction to non-carriers, LH does not significantly predict TT levels in BRCA carriers. The reasons for these differences are still a mystery and further research is warranted in a larger BRCA carrier cohort including patients with and without PCa. Incorporation of validative measurements of hormonal levels over time would also have a significant impact. In addition, genetic testing assessing the same mutations in Taylor’s et al.  study shAfter institutional review board approval, BRCA carriers and non-carriers between the ages of 40-70 were prospectively enrolled in our study during the years 2015 – January 2016. All participants provided written informed consent for participation in the study. All study participants were enrolled after testing performed in our unique BRCA male clinic, operated in our tertiary medical center. Participants came to our clinic to be tested for BRCA 1& 2 mutations due to a significant familial cancer history. The testing was done for all known 15 founder mutations in Jews, i.e., ‘‘The Jewish panel’’ -42 in BRInclusion criteria included males between 40-70 who were genetically confirmed to be BRCA carriers or non-carriers and able and willing to sign an informed consent. The exclusion criteria included any history of PCa therapy or BPH surgery and any endocrinologic disease, due to its possible effect on the hormonal status.Medical comorbidities of all patients were recorded and blood tests were taken, including PSA, TT, FSH, LH, FAI, SHBG and prolactin. Blood samples were collected between 0800 AM and 1100 AM to minimize the confounding effects of diurnal variation in the concentration levels of the hormones. The levels of PSA, TT, LH, FSH and prolactin, were measured by radioimmunoassay. All results were analyzed and compared between both groups.Statistical analysis included descriptive analysis , standard deviation for continuous variables, proportions for discrete variables, and comparative tests (chi-square for discrete variables and Mann-Whitney for continuous variables). MLRA were done to compare predictors of hormonal levels among carriers and non-carriers. Furthermore, tests were performed to assess if the data in the MLRA met the assumption of collinearity. All analyses were calculated using the SPSS software version 23.0 . All statistical tests were two - tailed and a p value of 0.05 was considered statistically significant.


There are multiple errors present in this work. The email for Corresponding Author Gui-Rong Li is incorrect. It should be grli@hkucc.hku.hk.There are two errors in the "Inhibition of hKv4.3 current by acacetin" portion of the Results section. -There is an error in the last line of the third paragraph. The correct sentence reads: "The current was significantly inhibited by acacetin ." -There is an error in the penultimate sentence of the last paragraph. Figure 2E should be referenced following the word "constant." The sentence should read: "The inactivation time constant  of Kv4.3 current was significantly reduced by 3 or 10 μM acacetin at all test potentials .There are two errors in the “Molecular determinants of hKv4.3 channel blockade by acacetin” portion of the Results section. - The penultimate sentence of the first paragraph should reference Figure 6B and not Figure 7B. The correct sentence reads: “The mean values of percentage inhibition of hKv4.3 currents are illustrated in Fig. 6B.”50s (at 0.2 Hz) of acacetin in inhibiting hKv4.3 currents were 7.9 μM for WT, 44.5 μM for T366A, 25.8 μM for T367A, 17.6 μM for V392A, 16.2 μM for I395A, and 19.1 μM for V399A, respectively.- In the second sentence of the second paragraph, T366A is incorrectly marked T366. The correct sentence reads: The ICtotal, total current; ISS, steady-state (or sustained) current.”There is an error in the legend for Figure 2A. The correct legend reads: "Time course of hKv4.3 current recorded in a representative cell with the voltage step shown in the inset during control and after 10 μM acacetin superfusion for 6 min without the voltage pulse depolarization and for 2 min with the voltage pulse depolarization, then drug washout. The currents recorded at corresponding time points are shown in the right of the panel. IThere is an error in the legend for Figure 6B. The correct legend reads: “Mean percent inhibition of WT and mutant hKv4.3 currents by 30 μM acacetin .


The lifesaving chemotherapy and radiation treatments that allow patients to survive cancer can also result in a lifetime of side-effects, including male infertility. Infertility in male cancer survivors is thought to primarily result from killing of the spermatogonial stem cells (SSCs) responsible for producing spermatozoa since SSCs turn over slowly and are thereby sensitive to antineoplastic therapies. We previously demonstrated that the cytokine granulocyte colony-stimulating factor (G-CSF) can preserve spermatogenesis after alkylating chemotherapy (busulfan).Male mice were treated with G-CSF or controls before and/or after sterilizing busulfan treatment and evaluated immediately or 10–19 weeks later for effects on spermatogenesis.We demonstrated that the protective effect of G-CSF on spermatogenesis was stable for at least 19 weeks after chemotherapy, nearly twice as long as previously shown. Further, G-CSF treatment enhanced spermatogenic measures 10 weeks after treatment in the absence of a cytotoxic insult, suggesting G-CSF acts as a mitogen in steady-state spermatogenesis. In agreement with this conclusion, G-CSF treatment for 3 days before busulfan treatment exacerbated the loss of spermatogenesis observed with G-CSF alone. Reciprocally, spermatogenic recovery was modestly enhanced in mice treated with G-CSF for 4 days after busulfan. These results suggested that G-CSF promoted spermatogonial proliferation, leading to enhanced spermatogenic regeneration from surviving SSCs. Similarly, there was a significant increase in proportion of PLZF+ undifferentiated spermatogonia that were Ki67+ (proliferating) 1 day after G-CSF treatment.Together, these results clarify that G-CSF protects spermatogenesis after alkylating chemotherapy by stimulating proliferation of surviving spermatogonia, and indicate it may be useful as a retrospective fertility-restoring treatment.The online version of this article (doi:10.1186/s12958-016-0226-1) contains supplementary material, which is available to authorized users. The cytokine granulocyte colony-stimulating factor promotes spermatogenic regeneration from surviving spermatogonia after high-dose alkylating chemotherapy in a manner that involves enhanced proliferation of undifferentiated spermatogonia.Currently, survival rates for childhood cancer  in the US and abroad exceed 84% due to advent of more effective, life-saving cancer treatments . As a rAs a result of this clinical need for fertility preservation strategies in pre-pubertal cancer patients, a number of experimental approaches have been under intense development –16, and However, before G-CSF treatment can be translated to the clinic as a fertility preservation/restoration agent, more thorough examination of efficacy and mechanism of action must be undertaken. Indeed, a number of questions arose as a result of our initial study, including: 1) whether G-CSF-induced spermatogenic protection against busulfan sterilization was stable longer than the 10 weeks previously examined, 2) whether G-CSF treatment influences steady-state spermatogenesis, 3) the precise temporal window during with which G-CSF promotes spermatogenic recovery after busulfan treatment, and 4) whether G-CSF promotes proliferation of undifferentiated spermatogonia, in vivo. This present study addresses these open questions and provides additional evidence supporting the concept that treatment with G-CSF protects spermatogenesis from alkylating chemotherapies by driving proliferation of surviving undifferentiated spermatogonia. As a result, it now appears that G-CSF treatment would be most useful as a fertility-restoring adjuvant therapy to promote enhanced spermatogenic recovery and future fertility after sterilizing cancer treatments.Male C57BL/6 mice were purchased from The Jackson Laboratory and maintained with ad libitum normal laboratory diet. All experiments utilizing animals were approved by the Institutional Animal Care and Use Committee of the University of Texas at San Antonio (Assurance A3592-01) and were performed in accordance with the National Research Council Guide for the Care and Use of Laboratory Animals.Five week old male mice were given subcutaneous injections of recombinant human granulocyte colony-stimulating factor (PeproTech) suspended in Dulbecco’s phosphate-buffered saline  containing 0.5% bovine serum albumin fraction V  or 0.5% BSA in DPBS alone (vehicle), as described previously . G-CSF dTestes from each animal were weighed and fixed with fresh 4% paraformaldehyde, paraffin-embedded and sectioned (5 μm) and cross-sections were H&E stained. Composite tiled mosaic images of eight testis sections (≥35 μm offset between each section) were obtained at 20X magnification using an AxioImager M1 (Zeiss) and an AxioCam ICc1 (Zeiss). Round seminiferous tubule cross-sections in each image were categorized according to the degree of spermatogenesis as described previously  based on2) values of ≥0.8] were used for subsequent analyses, an approach used previously to define roundness of isolated cells [Seminiferous tubule diameters were calculated automatically using a digital image processing algorithm developed in MATLAB 2015b  revised from a previous iteration  to improed cells –21. TubuOne epididymis from each animal was used to quantify sperm counts using a swim-up technique. Briefly, each complete epididymis was minced in room temperature DBPS, incubated at 37 °C for 30 min to allow motile sperm to swim out of the ducts and sperm number per ml was determined by hemocytometer after PFA fixation.In experiment 3, testes sections were stained with antibodies against γH2A.X to identify spermatocytes (marker of DNA double-strand breaks) and with lectin peanut agglutinin (PNA) to label terminal β-galactose found on spermatid acrosomes. In experiment 4, testis sections from treated mice generated previously  were stap ≤ 0.0285; Fig. In our first experiment . The Kiatogonia ). As expPreserving and restoring male fertility after chemotherapy and radiation treatments for cancer and other non-malignant disorders has received significant scientific attention for more than a decade, and in particular, fertility preservation among pre-pubertal boys who are not yet making sperm has been a major research focus around the world , 35–37. Notably, though, the efficacy of busulfan sterilization  was variable both between studies and within the current study. For instance, we previously reported that ~9.5% of tubule cross-sections contained any degree of spermatogenesis , yet we Since the receptor for G-CSF, colony-stimulating factor 3 receptor (CSF3R), has been previously detected on the cell surface of cultured THY-1 Cell Surface Antigen + (THY1+) undifferentiated spermatogonia , it was G-CSF binding to its receptor promotes cellular proliferation in a variety of tissues, both in vivo and in vitro –56. TherWhile it would not have been informative to examine spermatogonial proliferation directly in the animals from experiment 3, since the effects of G-CSF would have been realized only at the time of treatment, we did revisit the proliferative index among undifferentiated spermatogonia from mice treated with G-CSF and analyzed acutely thereafter . A smallLike previous studies in both males and females , 57, 58,Granulocyte colony-stimulating factor (G-CSF) appears to promote proliferation of undifferentiated spermatogonia, which leads to a modest enhancement of spermatogenic regeneration from surviving spermatogonia after high-dose alkylating chemotherapy. G-CSF treatment alone also enhances spermatogenic parameters, suggesting a role in steady-state spermatogenesis.


A growing number of cerebrospinal fluid biomarkers are now available to capture different aspects of Alzheimer's disease. People are increasingly aware that these biomarkers represent a real‐time reflection of pathological mechanisms that are ongoing in the brain. These novel markers can be added to the panel of existing ones like amyloid beta, total Tau and phosphoTau that are currently used for sensitive diagnosis of Alzheimer's disease, either alone or in combination. From the first publication showing that Aβ42 levels were decreased in Alzheimer's patients, it has taken 20 years of research to reach the current status. Since then, numerous papers have shown that the combination of this marker with tTau and pTau has a good discriminatory value even in early predementia stages. These 20 years of research have yielded important information on their biological significance: for example, decreased Aβ42 nowadays tells to us that amyloid pathology is ongoing in the brain. Even in preclinical Alzheimer's disease (AD), Aβ42 levels change as early as 15–20 years before any clinical symptoms become apparent. Increased tTau has a stronger relation with disease progression, for example, predicts conversion to dementia in patients with mild cognitive impairment (MCI), the prodromal phase of AD  Alzheimer biomarkers [amyloid β or Aβet al, et al, et al, 42 but shows a clear correlation with cognitive impairment  is puzzling, since tTau is an aspecific marker of neuronal damage in neurological diseases  There is a large body of consistent results in the literature, showing elevated levels in many neurological diseases , a protein likely released from neurons during acute axonal damage. It is not et al in this issue of EMBO Molecular Medicine , first become amyloid positive, and hence, amyloid‐positive SCD patients are included as a distinct group in the study. During disease progression, amyloid‐positive patients develop MCI and ultimately clinical AD. MCI patients that are not amyloid positive are by definition not of the Alzheimer type and thus can be seen as a separate group. The authors studied the levels of tTau, neurogranin, and NfL in these distinct groups. The results showed that (i) optimal discrimination between AD and SCD is obtained when tTau is combined with NfL, while neurogranin does not offer added value here; (ii) the amyloid‐positive patients have higher tTau and neurogranin levels, a pattern that is consistent over disease development, while NfL levels did not depend on amyloid status, as schematically represented in Fig http://www.neurochem.info, see Box 1), clinical routine is well opened to include novel neurological markers. We expect that only a few years will therefore be needed to see this clinically important implementation.Because several biomarkers have proven useful, and with the emergence of important consortia such as the Society for Neurochemistry and Clinical CSF analysis  is a network of experts, founded in 2015, as a spin‐off of projects such as BIOMARKAPD, SOPHIA, and BioMS‐network, which were all aimed at standardizing and developing guidelines for clinical implementation of CSF biomarkers. This society is a typical body to consult for the development of clinical guidelines incorporating CSF biomarkers. The Society moreover organizes symposia and regional courses to introduce neurologists and neurochemists into CSF as a diagnostic tool, addressing questions such as how to interpret basic CSF analysis, how to perform a lumbar puncture, how to interpret abnormal cellular CSF findings, and the state of the art of CSF biomarker use for several neurological diseases.The Society for Neurochemistry and Clinical CSF analysis (


The contrast sensitivity function (CSF), delineating contrast sensitivity over a wide range of spatial frequencies, provides a comprehensive characterization of spatial vision and a sensitive test for many physiological and pathological processes. A precise CSF measurement tool for the aging population is of great theoretical and practical importance. In the current study, we tested whether the assumptions of the newly developed quick CSF method were valid and whether it can rapidly, reliably, and effectively evaluate CSFs in the aging population. The quick CSF method combines Bayesian adaptive inference with an information gain strategy to directly estimate four parameters that define the observer’s CSF. Eighteen young and twenty-five old observers participated in the evaluation of the quick CSF method. All observers were screened for ophthalmological and mental diseases. Our results showed that the CSFs derived from the quick CSF method well matched with those from the traditional Ψ method, with excellent test-retest reliability. More importantly, the quick CSF method can accurately detect the difference of CSFs between the young and old groups. Aging significantly degrades contrast sensitivity. The quick CSF method demonstrates great potentials for both laboratory research and clinical applications in the aging population. Age-related vision decline or impairment affects the quality of life14. It increases the probability of falls in locomotion16 and crash risk during driving17, and has been related to age-related declines in other cognitive and behavioral functions. For example, Lin and colleagues18 found that impairment of distant visual acuity was associated with cognitive retardation in a large sample of older women. Salthouse, Hancock, Meinz and Hambrick19 found that impairment of near visual acuity significantly affected working memory, associative learning and concept identification.Aging is an irreversible stage of human life. Aging, either normal or pathological, impairs a variety of visual functions, including visual acuity20. Delahunt, Hardy, and Werner21 found that the decline of contrast sensitivity in the elderly could account for increased orientation discrimination thresholds. Greene and Madden22 showed that only contrast sensitivity remained significantly different between old and young observers after taking into account the correlations among near acuity, distant acuity, stereopsis, and contrast sensitivity. In addition, many studies showed that even after visual acuity was compensated, contrast sensitivity was still impaired by aging5. These studies highlight the importance and necessity of evaluating contrast sensitivity in monitoring age-related vision decline.Among all the affected visual functions, contrast sensitivity, or sensitivity to luminance variations, is one of the most fundamental functions of the visual system23. Clinical CSF tests, e.g. the Pelli-Robson chart24, Vistech contrast sensitivity chart25 and its descendants, the Functional Acuity Contrast Test (FACT)26, the Contrast Sensitivity Tester 1800 , and CVS-1000 series chart  can be used to get a rough estimate of the CSF but are not very precise because of the coarse sampling of stimulus contrast and spatial frequency28; laboratory implementations of CSF measurements using more objective psychophysical methods are usually time-consuming  and impractical for clinical applications in special populations. Lesmes, Lu, Baek, and Albright29 developed the quick CSF method based on the Bayesian adaptive framework to measure CSF with as few as 50 trials by optimally sampling both stimulus contrast and spatial frequency to maximize information gain over the CSF parameters in each trial. The quick CSF method has been successfully applied to measure CSF in both foveal31 and peripheral vision32 of normal observers, and in foveal vision of amblyopic observers33.The contrast sensitivity function (CSF), delineating contrast sensitivity over a wide range of spatial frequencies, provides a comprehensive characterization of spatial vision and a sensitive test for many physiological and pathological processes29. First it assumes that a CSF curve can be described by a four-parameter truncated log-parabola34. The second assumption is that the slope of the psychometric functions37 across all the spatial frequencies and observers is fixed. If they were invalid, these assumptions would adversely affect the performance of the method. Model mismatch between the assumed properties of the CSF in the quick CSF method and the actual properties of the observer can introduce systematic bias into the estimated CSFs.The quick CSF method has two important assumptions40. This could lead people to question the validity of the truncated log parabola model of the CSF in the aging population. Furthermore, Bennett, Sekuler, Ozin41 reported that the calculation efficiency was lower for old than for young observers. Pardhan42 recently found that, compared with young subjects, older subjects showed lower sampling efficiencies at low spatial frequencies and higher equivalent noise levels in high spatial frequencies, indicating that the neural and optical factors might affect contrast sensitivity loss with aging differently. These results suggest that we must carefully examine the fixed slope assumption of the quick CSF method. Taken together, a rigorous test and accompanying analysis have to be carried out before we can apply the quick CSF method in the aging population.It has been reported that the contrast sensitivity in aging exhibited more prominent loss in high spatial frequencies than in low spatial frequencies43, and evaluated the test-retest reliability of the quick CSF method through repeated measurements at both intermediate and far viewing distances. The results showed that the quick CSF method with 50~100 trials can effectively characterize the contrast sensitivity function in the aging population and discriminate the aged from the young control group at both distances. The underlying assumptions of the quick CSF method were valid in the aging population.In this study, we tested whether the quick CSF method can accurately and efficiently assess the CSF in the aging population by comparing CSFs obtained with the quick CSF method with those obtained with the traditional Ψ method45 on the validity of quick CSF methods. All experimental setups and subject inclusion criteria, unless otherwise noted, were the same in the two experiments.The study consisted of two experiments, one performed at a viewing distance of 1.86 meters  and the other at 4.29 meters , to evaluate the effects of presbyopic blurTen young observers  and seventeen old observers (68.4 ± 4.9 yrs) participated in Experiment 1. Eight young observers (24.0 ± 2.1 yrs) and eight old observers (65.5 ± 4.8 yrs) participated in Experiment 2  or 4.29 meters (Experiment 2). The viewing distance in Experiment 2 was comparable to the distance at which distant visual acuity was measured (5 meters).Experimental stimuli were generated using a computer running Matlab with PsychToolBox extensionsThe stimuli were oriented 3° × 3° sinewave gratings . To minimize edge effects, a half-Gaussian ramp (σ = 0.5°) was used to blend the gratings into the background.γmax; (2) the peak spatial frequency fmax; (3) the low-frequency truncation 𝛿; and (4) the bandwidth β–the function’s full-width at half maximum (in octaves). Different combinations of parameter values are assigned a prior as a four-dimensional probability density function (pdf). The pdf is updated using Bayes’ rule based on observer’s response in identifying the orientation of a grating of a certain contrast and spatial frequency level in each trial. The contrast and spatial frequency of the stimulus in the next trial is chosen such that the expected entropy of the pdf after the trial would be the lowest among all possible stimuli . In the current implementation, the contrast varied from 0.1% to 99% in steps of 1.5 dBs and spatial frequency was sampled from 0.5 to 16 c/d in steps of 3 dBs. For CSF parameters, the peak gain was sampled from 10 to 400 in steps of 0.1 dBs, the peak spatial frequency was sampled from 0.25 to 12 c/d in steps of 0.1 dBs, the low-frequency truncation was sampled from 0.2 to 2 in steps of 1.2 dBs and the bandwidth was sampled from 0.05 to 2 in steps of 1.2 dBs. The prior of the four parameters was generated using a 4-D Hyperbolic Secant distribution, with μ of log10(60), log10(2), log10(0.5), log10(0.5) and standard deviation of 2, 1, 1, 1 for the four parameters, respectively.The quick CSF method assumes that the CSF curve can be characterized with a truncated log parabola with four parameters: (1) the peak gain (contrast sensitivity) Pc is fraction correct, α is the lapse rate and set to be 0.02, μ is the guessing rate of 0.5, τ is the contrast threshold at 80.3% performance level, and η is the slope of the psychometric function and set to be 3.549. Our results in the “Evaluating the Constant Slope Assumption” Section showed that exact matching of the assumed slope and the observer’s real slope is not critical for threshold estimation, consistent with Hou et al.33.A log-Weibull psychometric function was adopted in threshold estimation:A grating orientation identification task was used. Each trial started with a 294-ms fixation cross in the center of the screen, with a brief tone signaling each trial’s onset. This was followed by a 153-ms blank screen, and a 141-ms grating stimulus that was tilted either 45° clockwise or 45° counter-clockwise from vertical with equal probability. Observers were asked to report the orientation of the grating by a key press. No feedback was provided. The next trial started after response and an inter-trial interval of 588 ms.Observers were prescribed with 100 practice trials to get familiarized with the experimental setting and procedure. Each session of the main experiment had 600 trials, with 300 quick CSF trials and 300 Ψ method trials. For the Ψ method, we measured contrast sensitivity at six spatial frequencies , with 50 trials in each frequency. All trials from the two methods were intermixed. All observers participated in two experimental sessions, separated by 0.5 to 8 days. The results of the measurements were quantified in terms of the area under log contrast sensitivity function (AULCSF) and contrast sensitivities at the six spatial frequencies tested in the Ψ method. The results from the Ψ method were treated as the “truth” and used to evaluate the accuracy of the quick CSF method.50.To obtain CSF estimates from each run of the quick CSF method, we sampled 1,000 sets of CSF parameters from the posterior distribution of CSF parameters, constructed 1,000 corresponding CSF curves, and obtained the empirical distribution of the CSF. This re-sampling procedure automatically takes into account the covariance structure in the posterior distribution of the CSF parameters, and allows us to assess the precision of the estimated CSF curveFigure cs is the standard deviation of the distribution of resampled contrast sensitivity at each spatial frequency, N is the number of resampled spatial frequencies (N = 12), i indexes spatial frequency, and j indexes repetition. The precision index was calculated trial-by-trial and hence we will have 300 precision estimations for the quick CSF and the Ψ methods, respectively.The precision of CSF estimates obtained with the quick CSF and Ψ methods was quantified by the average standard deviation of the distribution of resampled sensitivity estimates across all spatial frequencies for each observer:10 units after 50, 100, 300 trials, respectively; for the old group, the precision was 0.168 ± 0.044, 0.085 ± 0.023, and 0.034 ± 0.017 log10 units after 50, 100, 300 trials. The precision of the Ψ method was 0.057 ± 0.011 log10 units for the young group and 0.066 ± 0.027 log10 units for the old group after 300 trials.For the quick CSF method, the precision was comparable in 93.7% and 100% of the 300 trials  in the young and old group, respectively. Precision in the two groups didn’t differ significantly across most of the trials . Figure r2 = 0.949) and 0.939  for the young and old observers, respectively.We used Pearson correlation and linear regression analysis to evaluate the test-retest reliability of the Ψ method and the quick CSF method for the young and old observers. In Fig. r2 = 0.744), 0.953 , and 0.941  after 50, 100, and 300 quick CSF trials, respectively. For old observers, the test-retest correlations were 0.911, 0.966 and 0.974  after 50, 100, and 300 trials, respectively. The slopes of linear regression were 0.868 , 0.917 , and 0.973  after 50, 100 and 300 trials.Contrast thresholds at six spatial frequencies after 50, 100, and 300 quick CSF trials for the young and old observers in the first experimental session are plotted against those in the second session in Fig. 51. Figure We also compared the test-retest reliability of the contrast sensitivity functions obtained with the quick CSF method using Bland-Altman plotsTo evaluate the consistency between estimated CSFs from the quick CSF and Ψ methods, we conducted Pearson correlation and linear regression analysis on the contrast threshold for the young and old observers at six spatial frequencies in the first and second sessions see Fig. . The absM is the number of observers and N is the number of spatial frequencies.The mean absolute difference over spatial frequencies and observers in each group was computed asr2 = 0.804), 0.964 , and 1.026  in the first session and 0.803 , 0.940 , and 0.954  in the second session, respectively. The mean absolute difference of contrast sensitivity between the quick CSF and Ψ methods after 50, 100, and 300 trials were 3.336 ± 0.353 (mean ± se), 2.815 ± 0.340, and 2.408 ± 0.261 dB in the first session and 2.449 ± 0.333, 1.919 ± 0.217 and 1.528 ± 0.144 dB in the second session.For young observers, the correlation coefficients of CSFs obtained from the quick CSF and Ψ methods were 0.897, 0.959 and 0.983  after 50, 100, and 300 quick CSF trials in the first session and 0.916, 0.964 and 0.976  in the second session. The results of linear regression showed that the slopes after 50, 100, and 300 quick CSF trials were 0.903  and 0.909 , 0.983  and 0.963 , and 0.939  and 0.966  after 50, 100, and 300 quick CSF trials. The mean absolute difference of contrast sensitivity obtained from the two methods in the first and second sessions were 2.472 ± 0.218 and 2.768 ± 0.235, 1.791 ± 0.165 and 2.226 ± 0.199 dB, and 1.440 ± 0.142 and 1.332 ± 0.128 dB after 50, 100, and 300 quick CSF trials, respectively.The correlation coefficients of the CSFs obtained from the two methods for the old observers in the first and second sessions were 0.955 and 0.940, 0.972 and 0.973, and 0.981 and 0.978  after 50, 100, and 300 quick CSF trials, respectively. The results of linear regression in the first and second sessions showed that the slopes were 0.940  showed that there were highly significant differences in contrast sensitivity between the young and old observers after 50, 100, and 300 quick CSF trials  = 26.794, 26.230, 29.716; all p < 0.001). A Post-hoc between-group t-test revealed that contrast sensitivity in the young group was significantly greater than that in the aged group for all tested frequencies  = 1,858~5.426, 2.482~5.729, and 4.063~4.750 for 50, 100, and 300 trials, respectively; all p < 0.05). Furthermore, the interaction of spatial frequency and age was significant  = 6.346, 4.902, and 2.863; all P < 0.05), indicating that the difference in contrast sensitivity varied with spatial frequency. Averaged over subjects, the difference in contrast sensitivity between the aged and young groups increased from 0.13 ± 0.02 for 50 trials, 0.13 ± 0.01 for 100 trials, 0.21 ± 0.01 for 300 trials at 0.5 c/d to 0.43 ± 0.02, 0.41 ± 0.02, and 0.37 ± 0.02 at 16 c/d, indicating greater degradation at higher frequencies. Figure 54, and cutoff spatial frequency (cutSF) that characterizes the high spatial frequency limit of spatial vision as predictors. The AULCSF was calculated as the integration of the area under the log CSF curve and above 0 from 0.5 to 16 c/d. The cutSF was defined as the spatial frequency at which contrast sensitivity is 1.0 (threshold = 1.0). We used a logistic regression analysis to predict membership in the two groups:P(old) is the probability of being an old observer, and β0, β1, β2 are the coefficients.The significant difference in CSF between the old and young groups prompted us to evaluate whether CSF is a good indicator of aging. We selected the Area Under the Log CSF (AULCSF), a summary metric of the CSF functionβ0 and β1  had significant impact on the prediction, but β2  didn’t in almost all the conditions . That is, AULCSF was the key factor for discriminating CSFs from the two groups. The results of Hosmer and Lemeshow goodness-of-fit (H&L GOF) test showed that there were no significant difference between the predicted and the observed values .The accuracy of the prediction was 74.1%, 85.2% and 92.6% after 50, 100, and 300 quick CSF trials in the first session and 88.9%, 85.2%, and 85.2% in the second session. One assumption of the quick CSF method is that the CSF can be characterized by a truncated log-parabolic function. If the shape of the CSF in the aging population were not well described by the truncated log-parabolic function, the quick CSF method would not provide an accurate measure of the CSF in the aging population. To validate the assumption, we fit the contrast sensitivities at six spatial frequencies (obtained with theΨmethod) with the truncated log-parabolic function:r2 in the young group was 0.95 ± 0.01 and 0.94 ± 0.01 after 300 trials in the two test sessions, respectively. Consistent with previous research34, the truncated log-parabolic function provided an excellent description of the CSFs of the young population. For the old group, the mean r2 was 0.96 ± 0.01 and 0.94 ± 0.01 after 300 trials in the two test sessions, respectively. The truncated log-parabolic model provided an excellent description of the CSFs of the old population.The mean In our implementation of the quick CSF method, there was one important assumption, that is, the slope of the psychometric function is invariant across spatial frequencies. A violation of this assumption might lead to evident bias and inaccuracy of evaluation. Validating the assumption is necessary for applications of the quick CSF method in the old population.i denotes a contrast condition, Ni and Ki are the number of total and correct trials, and Pi is the fraction correct predicted by the log-Weibull function. The goodness-of-fit was then evaluated by r2:where Ypredicted is the model-predicted psychometric function, and Ymeasured is the measured psychometric function.We binned the 100 Ψ trials for each spatial frequency from the two sessions into five equal contrast ranges (in log unit), calculated the fraction correct response corresponding to the mean of that range, and fitted a log-Weibull psychometric function , 0.972 (p < 0.001) and 0.975 (p < 0.001) after 50, 100, and 300 quick CSF trials, respectively. The slopes of linear regression were 0.942 , 0.974, and 0.941  after 50, 100, and 300 quick CSF trials, respectively. For the old group, the precision was 0.160 ± 0.035, 0.094 ± 0.029, and 0.038 ± 0.014 log10 units after 50, 100, 300 trials; the test-retest correlations were 0.949, 0.978 and 0.986  after 50, 100, and 300 trials, respectively; the slopes of linear regression were 1.014 , 1.037 , and 1.022  after 50, 100 and 300 trials. The correlation coefficients of CSFs obtained from the quick CSF and Ψ methods were 0.956, 0.977 and 0.983  after 50, 100, and 300 quick CSF trials in the first session and 0.953, 0.965 and 0.971  in the second session for the young observer. The correlation coefficients of the CSFs obtained from the two methods for the old observers in the first and second sessions were 0.921 and 0.917, 0.957 and 0.937, and 0.942 and 0.970  after 50, 100, and 300 quick CSF trials, respectively.For the young group, the precision was 0.158 ± 0.022 (mean ± sd.), 0.083 ± 0.014, and 0.026 ± 0.013 logModel comparison revealed that the slope invariance assumption could not be rejected . Averaged over observers, the best-fitting slope of the reduced model is 1.81 ± 0.52 in the young group and 1.73 ± 0.37 in the old group, with no significant difference (t (14) = 0.327, p > 0.10). The average slope over the two groups is 1.77 ± 0.44.The Bland-Altman analysis showed that only 4.86% and 5.56% of the scores were out of the 95% consistency boundaries in the young and old groups, respectively.ps > 0.10) and marginal difference in the young group  = 3.434 (p = 0.082), 2.628 (p > 0.10), and 3.261(p = 0.090), respectively).A between-observer analysis of variance (ANOVA) showed that there were highly significant differences in contrast sensitivity between the young and old observers after 50, 100, and 300 quick CSF trials  = 4.554, 8.005, and 5.798; all P < 0.05). Figure 29 in the aging population. Our results showed that the quick CSF method can be used to derive a reasonable CSF estimate with as few as 50 trials in about 3 to 5 minutes. The CSFs obtained from the quick CSF method well matched those from the traditional Ψ method43, with exceptionally good test-retest reliability. Furthermore, the quick CSF method can reliably detect the CSF difference between the young and old groups.In this study, we evaluated the reliability, accuracy, and efficacy of the quick CSF method33: (1) CSF can be described by a truncated log parabola function with four parameters, peak gain, peak spatial frequency, bandwidth, and truncation; and (2) the slope of the contrast psychometric function is invariant across spatial frequencies. Our results suggest that the CSF derived from the traditional Ψ methods can be well described by the truncated log parabola function. Also, we confirmed through model comparison that the slope invariance assumption was valid for almost all observers. Averaged over observers, the slope of contrast psychometric function was 1.94 ± 0.38 in the young group and 1.74 ± 0.41 in the old group at the intermediate viewing distance and 1.81 ± 0.52 in the young and 1.73 ± 0.37 in the old group at the far viewing distance, with no significant difference, consistent with findings in other studies55. Taken together, these results paved the way for using the quick CSF procedure in the aging population.There are two major assumptions in the implementation of the quick CSF procedure57.Test-retest correlations appeared to be higher in the older group, that is 0.911 vs 0.863 after 50 trials, 0.966 vs 0.954 after 100 trials, and 0.974 vs 0.975 after 300 trials at the intermediate viewing distance and 0.949 vs 0.936, 0.978 vs 0.972 and 0.986 vs 0.975 at the far viewing distance, particularly with reduced numbers of trials (i.e. 0.911 vs 0.863). We didn’t exactly know the reason. Our observation was that the old observers were more serious participants and were generally more alert during the experiment, consistent with the personality studies that showed that older adults are generally more conscientious than their younger counterparts45 in Experiment 1. To rule out this possibility, we conducted Experiment 2 at a far viewing distance, keeping all other experimental setups identical to those of Experiment 1. In general, all major conclusions remained the same when applying the quick CSF procedure at the far distance. Meanwhile, there was no significant difference in contrast sensitivity obtained at the intermediate and far viewing distances after 50, 100, and 300 quick CSF trials in both the young and old groups.It’s important to note that the old observers might potentially experience presbyopic blur due to less vergence/accommodation ability at the intermediate viewing distance52 found that contrast sensitivity decreased at all frequencies for 50–60 year old observers, but it only decreased at high spatial frequencies for 40 year old observers. Owsley, Sekuler, and Siemsen39 showed that contrast sensitivity decreased only in high spatial frequencies (>2 c/d) for 40–50 year old observers. In a later study, Sloane, Owsley, and Alvarez38 reported that contrast sensitivity decreased at all spatial frequencies and the decline was particularly marked in high spatial frequencies. They attributed the different results to different stimuli (stationary vs flicker grating) or stimuli sizes (4° vs 6°) used in the studies. In addition, Crassini, Brown and Bowman3 claimed that young observers only had better contrast sensitivities in relatively high spatial frequencies (e.g. 2.0 and 5.0 c/d) but not in low frequencies (e.g. 0.2 and 0.8 c/d). It’s important to note that stimulus characteristics , stimulus delivery method , age variability (40~80 years), and screening criteria  are different among the different studies in the literature, which may have contributed to the apparent discrepancies in the observed contrast sensitivity deficits in old observers.Although it’s commonly accepted that aging degrades contrast sensitivity, the spatial frequency selectivity of the degradation is still controversial. In the current study, we found that contrast sensitivity declined across all spatial frequencies in the aging population and the impact was more profound at high spatial frequencies. By producing interference fringe patterns directly on observers’ retinas, Nameda, Kawara, and Ohzup < 0.001). However, although there was significant correlation between AULCSF and visual acuity in the young group , AULCSF didn’t correlate with visual acuity in the old group , indicating that the degradation in contrast sensitivity in the old group cannot be solely accounted for by the decline in visual acuity. In Experiment 2, we found similar results . These results, taken together with previous reports59, indicate that the contrast sensitivity function provides additional information to that provided by visual acuity in the healthy aging population. Note that we set a logMAR normal or corrected visual acuity of better than 0.10 as one of the inclusion criteria , which is more strict than that used in other study60.What caused the decline of contrast sensitivity in aging? There are three possible explanations. First, the degradation of contrast sensitivity may simply reflect decreased visual acuity. In Experiment 1 of the current study, we did find that logMAR acuity differed between the aged and young groups (t(25) = −5.550, 61, e.g., reduction of retinal illumination due to smaller pupil size62, lower optical density of the ocular media63, and lens absorption64 in the aging population. The nature and extent of optical degradation on contrast sensitivity are still under debate. Generating interference fringe patterns using laser interferometry directly on the retina, Burton, Owsley, and Sloane5 found that the contrast sensitivity difference between the young and old adults shrunk greatly, implying that optical defects may be a major contributor to old observers’ sensitivity loss at photopic levels. With a similar method of stimulus presentation but a smaller visual field to bypass pupil size limitations and optical defects, Nameda, Kawara, and Ohzu52 got an opposite result that suggested there was no significant contribution of lens coloring on age-related decline of contrast sensitivity. Furthermore, the influence of senile miosis on the CSF of the elderly has been excluded by Sloane, Owsley, and Alvarez38. Bennett, Sekuler, and Ozin41 concluded that the decline of contrast sensitivity was not from reduced retinal illumination in aging.Second, decline of contrast sensitivity may come from optics-related degradation4. Using the linear amplification model (LAM), Pardhan, Gilchrist, Elliott, and Beh65 found that the decline of contrast sensitivity at a single spatial frequency of 6 c/d in old observers resulted from lowered neural calculation efficiency without any significant increase of internal additive noise. The result was supported by Bennett, Sekuler, and Ozin41 who conducted the test at 1, 3, and 9 c/d. They postulated that higher multiplicative noise and a mismatch between the spatiotemporal characteristics of the stimulus and the neural filter used to detect it might lead to lowered calculation efficiency. Pardhan42 further demonstrated that the decrease of visual function in old observers depended on the spatial frequency tested, with significantly lower calculation efficiencies at 1 and 4 c/d, and higher equivalent noise at 10 c/d. However, Allard, Renaud, Molinatti & Faubert66 found that healthy aging didn’t affect calculation efficiency in low spatial frequencies. They attributed the difference between the studies to the different spatial-temporal properties of the external noise patterns used in them. Electrophysiological studies from animals have attributed age-related losses in visual sensitivity to the decline of GABAergic inhibition in the aged visual cortex68, which may lead to a non-specific increase of neuron firing rate and therefore a decrease in signal-to-noise ratio. In addition, the direct morphological evidence from Hua and his colleages68 showed that the density of GABA-immunorective neurons in the striate visual cortex of old cats is significantly lower than that of young adult cats, supporting the GABA hypothesis.Finally, aging may impact neural processing of contrast signalsTo conclude, we show the quick CSF method, which adopts a Bayesian information-gain strategy to greatly reduce CSF testing time , can provide an effective and reliable estimate of contrast sensitivity in the elderly. The method has demonstrated great potentials for both laboratory research and clinical evaluation in the aging population.


The proportion of females enrolling into medical schools has been growing steadily. However, the representation of female residents among individual specialties has shown considerable variation. The purpose of this study was to compare the trends of gender representation in Otolaryngology – Head and Neck Surgery (OTL-HNS) residency programs with other specialty training programs in Canada. In order to contextualize these findings, a second phase of analysis examined the success rate of applicants of different genders to OTL-HNS residency programs.Anonymized data were obtained from the Canadian Residency Matching Service (CaRMS) and from the Canadian Post-M.D. Education Registry (CAPER) from 1988 to 2014. The differences in gender growth rates were compared to other subspecialty programs of varying size. Descriptive analysis was used to examine gender representation among OTL-HNS residents across years, and to compare these trends with other specialties. Bayesian hierarchical models were fit to analyze the growth in program rates in OTL-HNS based on gender.CaRMS and CAPER data over a 27 year period demonstrated that OTL-HNS has doubled its female representation from 20% to 40% between 1990 and 1994 and 2010-2014. The difference in annual growth rate of female representation versus male representation in OTL-HNS over this time period was 2.7%, which was similar to other large specialty programs and surgical subspecialties. There was parity in success rates of female and male candidates ranking OTL-HNS as their first choice specialty for most years.Female representation in Canadian OTL-HNS residency programs is steadily increasing over the last 27 years. Large variation in female applicant acceptance rates was observed across Canadian universities, possibly attributable to differences in student body or applicant demographics. Factors influencing female medical student career selection to OTL-HNS require further study to mitigate disparities in gender representation and identify barriers to prospective female OTL-HNS applicants. The proportion of female students pursuing postgraduate medical education has grown steadily . ConversThere are several advantages of gender equity among the physician workforce, including benefits to patient care. Specifically, a diverse workforce includes a broader range of physicians which increases the likelihood of addressing health inequalities and providing care to underserved populations . AlthougGender equity appears to be of considerable benefit beyond obvious moral and ethical interests. Gender misrepresentation may place limitations on the quality of selected resident trainees by inherently limiting the application process to a segregated pool of applicants . A speciWhen specifically considering Otolaryngology - Head and Neck Surgery (OTL-HNS), women were underrepresented compared to larger programs despite increasing female representation in OTL-HNS within American residency training programs , 17. InvTo our knowledge, there has been no published study on the nature or evolution of gender representation among Canadian Otolaryngology-Head and Neck Surgery (OTL-HNS) residents. The overarching goal of this study was to provide a descriptive analysis of the recent history of gender representation in residency training in Canada compared to OTL-HNS. We chose to compare Canadian OTL-HNS residency training programs to programs of similar and larger number of registered residents with a focus on growth rates of female trainees compared to male trainees. A secondary aim involved a comparison of acceptance rates to OTL-HNS residency training programs between male and female applicants across all Canadian institutions.n = 13) was assigned a randomly generated number between one and 13 in order to anonymize institutions for the purposes of analysis.Ethics approval was not required since this study was a post-hoc analysis of publically available data. Each postgraduate Canadian OTL-HNS residency program (We conducted a retrospective review of two databases: the Canadian Residency Matching Service (CaRMS) and the Canadian Post-M.D. Education Registry (CAPER). The Canadian Residency Matching Service (CaRMS) provided the following data from 2006 to 2014: gender representation of Canadian residency training programs, demographics of all Canadian OTL-HNS residency training programs, and demographics of medical students applying to Canadian OTL-HNS residency training programs. The CaRMS database captures all applicants participating in the annual CaRMS residency matching process. A matched candidate refers to a candidate who is accepted into a residency program to which they applied.CaRMS data prior to 2006 was deemed unreliable due to an incomplete data set. Therefore, the Canadian Post-M.D. Education Registry (CAPER) provided Canadian resident demographics including gender representation from 1988 to 2005. This data stems from a self-reported census completed by all resident trainees and submitted by the postgraduate medical education offices of each Canadian medical school to CAPER for archiving.We measured female representation by analyzing self-reported gender for CAPER data and using the statistics provided by CaRMS. Trends in female representation among Canadian OTL-HNS residency programs were compared to other similarly-sized surgical subspecialties, such as cardiac surgery, neurosurgery, ophthalmology, orthopedic surgery, plastic surgery and urology. Comparisons were also made to larger training programs such as family medicine, internal medicine, general surgery, anaesthesiology, pediatrics and psychiatry. Difference in growth rates between genders in OTL-HNS programs was calculated and compared to both similarly-sized surgical subspecialties as well as larger-sized residency programs. Finally, we compared success rates of female and male applicants and analyzed differences across institutions.Descriptive statistics and graphical trends over time were compiled for each residency training program across all years. Bayesian hierarchical Poisson regression models were fit in order to analyze trends over time and compare these trends between males and females across different residency training programs. At the first level of our hierarchical model, the count for each program within each year and for each gender were assumed to follow a Poisson distribution with a rate lambda, assumed different for each data point. Poisson rates were therefore permitted to vary for each year, program and gender. At the second level of our hierarchical model the natural logarithm of these rates followed a linear regression model, with each rate lambda regressed based on program, year, and gender. In order to account for different baseline levels within each program, different intercepts were used in the linear regression model for each program. Similarly, to account for different trends over time within each specialty, each were also given their own slope. At the third level of the hierarchical model non-informative prior densities were used for all parameters, so that the data drive the final inferences. To interpret the estimated regression coefficients on the count scale rather than on the logarithms of these counts, the exponential of the estimated coefficients were calculated. All parameters were estimated using the posterior median with 95% credible intervals. Credible intervals are the Bayeisan analogue to frequentist confidence intervals, but have the more natural interpretation that the probability of the estimated parameter is within the given interval is 95%. All analyses were carried out using WinBUGS .The proportion of females registered in a residency training program in Canada has increased within all programs included in our analysis, with female representation in OTL-HNS effectively doubling from 20%  to 40%  between 1990 and 1994 and 2010-2014  for our analysis with CAPER being a self-reported census represents an additional limitation of this study.Future work may include investigating the influence of medical curriculum and role model exposure on trainees’ selection of career paths during pre-clinical years. The investigations of other contributory factors such as gender role models, applicant perception of the given specialty, perception of lifestyle within the given specialty and the recruitment techniques employed by residency programs also represent interesting avenues of future study, and could provide explanations for the findings described here.Female representation in OTL-HNS continues to improve with a large variability in the success rate of female applicants across Canadian institutions. Despite progress towards gender parity in OTL-HNS residency programs in Canada, certain institutions continue to report underrepresentation of female residents, possibly due to certain characteristics unique to those residency programs. A better understanding of these trends may allow us to identify supports and barriers of gender parity in surgical training programs and ultimately suggest appropriate recommendations. This will lead to the most qualified trainees being selected, gender parity within the OTL-HNS workforce, and ultimately improved patient outcomes. Ensuring the presence of gender congruent role models and addressing the negative perception of work-life balance within subspecialty surgery could reduce barriers to female medical student trainees applying to OTL-HNS residency training programs, and careful monitoring or admissions practices may facilitate the matching of the most appropriate candidates, regardless of gender.


Calretinin‐expressing (CR+) interneurons are the most common type of striatal interneuron in primates. However, because CR+ interneurons are relatively scarce in rodent striatum, little is known about their molecular and other properties, and they are typically excluded from models of striatal circuitry. Moreover, CR+ interneurons are often treated in models as a single homogenous population, despite previous descriptions of their heterogeneous structures and spatial distributions in rodents and primates. Here, we demonstrate that, in rodents, the combinatorial expression of secretagogin (Scgn), specificity protein 8 (SP8) and/or LIM homeobox protein 7 (Lhx7) separates striatal CR+ interneurons into three structurally and topographically distinct cell populations. The CR+/Scgn+/SP8+/Lhx7− interneurons are small‐sized , possess tortuous, partially spiny dendrites, and are rostrally biased in their positioning within striatum. The CR+/Scgn−/SP8−/Lhx7− interneurons are medium‐sized , have bipolar dendrites, and are homogenously distributed throughout striatum. The CR+/Scgn−/SP8−/Lhx7+ interneurons are relatively large‐sized , and have thick, infrequently branching dendrites. Furthermore, we provide the first in vivo electrophysiological recordings of identified CR+ interneurons, all of which were the CR+/Scgn−/SP8−/Lhx7− cell type. In the primate striatum, Scgn co‐expression also identified a topographically distinct CR+ interneuron population with a rostral bias similar to that seen in both rats and mice. Taken together, these results suggest that striatal CR+ interneurons comprise at least three molecularly, structurally, and topographically distinct cell populations in rodents. These properties are partially conserved in primates, in which the relative abundance of CR+ interneurons suggests that they play a critical role in striatal microcircuits. The output of SPNs is thought to be sculpted by an array of different types of striatal interneurons. GABAergic interneurons expressing the calcium‐binding protein (CBP) calretinin (CR) are the most abundant class of interneuron in the primate striatum  male Sprague Dawley rats (Charles River) and 6 adult, 3‐month‐old C57Bl/6J male mice (Charles River) in accordance with the Animals (Scientific Procedures) Act, 1986 (UK). After being deeply anaesthetized using isoflurane (4% v/v in oxygen), each rat was given a lethal dose of pentobarbitone  followed by transcardial perfusion with approximately 50 mL of 0.05 M phosphate‐buffered saline, pH 7.4 (PBS), followed by 300 mL of fixative ). This was followed by a third perfusion of approximately 200 mL of fixative . Mice were deeply anesthetized with pentobarbitone and perfused transcardially using 20 mL of PBS, followed by 20 mL of fixative . For both species, once the brain was removed, the tissue was post‐fixed in this solution for 24 hr at 4°C. Using a vibrating microtome (Leica VT1000S), 50‐µm‐thick coronal sections containing the striatum were cut and collected for immunofluorescence processing. For some images, 50‐µm‐thick parasagittal sections were used to visualize the medial striatum.2.2Sections were washed with PBS and pre‐incubated for 2 hr in a solution consisting of 10% v/v NDS  and 0.3% v/v Triton X‐100 in PBS. After further washing using PBS, sections were incubated overnight at room temperature in a solution of 0.3% v/v Triton X‐100 in PBS containing primary antibodies . For analyses of mouse dorsal striatum, 9 coronal planes were used . Sections from different animals of the same species were matched to similar stereotaxic planes along the rostral‐caudal axis (±50 µm) using the appropriate atlas  running Axiovision software (Carl Zeiss) and equipped with a 20X  objective and StereoInvestigator 9.0 software (MBF Biosciences) was used to delineate the dorsal striatum. In order to image each fluorescence channel, the following sets of filter cubes were used: AMCA ; AlexaFluor‐488 ; Cy3 ; and DyLight 649 . The borders of the dorsal and ventral striatum were determined using the boundaries defined in standard stereotaxic atlases for rat  at depths 2–12 μm from the upper surface of each section at the level of the striatum. This was done using the 20× 1.8 NA objective lens of an epifluorescence microscope (as above). The thickness of the section was measured at each counting site and then averaged to obtain a correction factor for tissue shrinkage. The average section thickness was found to be 47.8 ± 0.73 µm in rats meaning that the calculated shrinkage factor was ∼4.4%. In mice, the average section thickness was found to be 46.5 ± 0.66 µm, resulting in a calculated shrinkage factor of ∼7.0%. To minimize confounds arising from surface irregularities, neuropil within a 2 μm “guard zone” at the upper surface was not imaged. By sampling sections in this manner, a 10 µm‐thick “optical disector” was generated which had abutting, unbiased 2D counting frames (320 × 420 µm) consisting of two perpendicular exclusion lines and two inclusion lines. This was used to generate all stereological cell counts and molecular expression profiles presented in this study . A labeled neuron was counted if the top of its nucleus came into focus within the optical disector. If the nucleus was already in focus at the top of the optical disector, the neuron was excluded West, . As stro2.4Once the number of neurons expressing a marker or markers had been counted and recorded for a given coronal plane, the volume of the striatum in which these neurons had been counted was calculated using StereoInvestigator 9.0 software (MBF Biosciences). The software uses a method that is derivative of the point counting method  is the volume of that structure.In order to calculate an estimate for the total number of a given type of neuron in the striatum, the following equation , was calculated according to the following  is the area represented by each point, and t is the fixed distance between each section. When calculated in this manner across the striatum of six rats, the mean volume of the dorsal striatum was determined to be 24.2 ± 2.1 mm3, a value that resembles previous estimates  was determined to be 9.4 ± 0.5 mm3. Once the value of V(ref) is determined, multiplying that volume by the mean neuronal density yields an estimate for the total number of neurons for that animal. Because most neuronal counts were performed across three animals , in depth statistics were deemed inappropriate, and so the value calculated from each animal is plotted along with the mean.Once complete, the volume of the structure, m = 1) less than 0.1 is the agreed upon value which indicates that the level of variation in striatal volume calculation between different animals is a product of biological, rather than methodological variation  was calculated using the Stereo investigator software. In all such studies, a CE . Using previously described analyses . Mann‐Whitney U tests where used to compare the mean positional values of two different interneuron populations along the medio‐lateral or dorso‐ventral axis within a given coronal plane. The minimum significance level for these statistical tests was taken to be p ≤ .05, and is denoted by the presence of a box (□). Multiple comparisons across sections were corrected using the false discovery rate (FDR) method  somatodendritic features of some CR+ neurons can be visualized simply using immunohistochemistry  followed by supplemental doses of ketamine  and xylazine . Local anesthetic was used to infiltrate the wound margins . A stereotaxic frame (Kopf) was used to fix the animal in place, and a homeothermic heating device (Harvard Apparatus) was used to maintain the animal's core body temperature at 37 ± 0.5°C. Recording of the electrocorticogram (ECoG) was performed directly above the frontal (somatic sensory‐motor) cortex   in accordance with the Animals (Scientific Procedures) Act 1986 (UK). As described previously , 50‐μm‐thick coronal sections were serially collected and subsequently washed in PBS for 10 min. Sections were then incubated for a minimum of 4 hr in a solution of Triton PBS and Cy3‐conjugated streptavidin . Sections were analyzed for Cy3 signal, and those containing neurobiotin‐labeled cells were isolated for further molecular characterization by indirect immunofluorescence  from the Yerkes National Primate Research Center colony. All procedures performed were in accordance with guidelines from the National Institute of Health and were approved by Emory's Animal Care and Use Committee. The highly experienced Yerkes veterinary staff took care of the animals. The Yerkes National Primate Research Center is an NIH‐funded institution that is fully accredited by AAALAC, and regularly inspected by USDA. All activities at the Center are in compliance with federal guidelines. All experimental protocols concerning primates are performed in strict accordance with the NIH Guide for the Care and Use of Laboratory Animals and the PHS Policy on the Humane Care and Use of Laboratory Animals, and are reviewed and approved by the Emory IACUC before the proposed studies begin. Both monkeys were anesthetized using an intravenous injection of pentobarbital (100 mg/kg). This was followed by a transcardial perfusion with cold oxygenated Ringer's solution, and 2 L of a fixative solution containing 4% paraformaldehyde and 0.1% glutaraldehyde in PB . Each brain was then cut into 10‐mm‐thick blocks in the coronal plane, which were subsequently cut into 50‐µm‐thick sections using a vibrating‐blade microtome. Sections containing the caudate/putamen were collected for use in immunofluorescence and cell counting procedures.Monkey tissue used for stereological cell counting was obtained from two female adult rhesus monkeys . The sections from each monkey were matched such that the overall position of each section relative to Bregma   could not be accurately performed due to the lack of rhesus tissue containing the tail of the caudate nucleus (approximately 10 mm of caudate was not acquired). As a result, this study could not accurately report estimates for the total numbers of neurons in the entirety of the caudate nucleus or the putamen. As such, the absolute density for each counted neuron is presented rather than the total number, and was calculated by averaging the density of counted neurons within each coronal plane (as in the rat and mouse). This was done so that the results obtained from counts of different neuronal populations in different species performed in this study could be compared with one another.For each combination of immunofluorescence markers studied, the number of labeled neurons was counted in the caudate or the putamen (treated as separate structures) and recorded for a given coronal plane using the same principles described for the rodent. The calculation of The distribution of all counted neurons in the caudate nucleus and the putamen was analyzed and presented along the rostro‐caudal, dorso‐ventral, and medio‐lateral planes in the same manner as for the dorsal striatum of rodents. Statistical analysis regarding the distributional bias of counted neurons was also performed similarly to what was done for the results obtained in rodent dorsal striatum.33.1In the adult rat, the CBP secretagogin (Scgn) is expressed in a proportion of striatal interneurons  than that of CR+/Scgn− interneurons . The somatic diameter of CR+/Scgn−/Lhx7+ interneurons  represent nearly 40% and CR+/Scgn−/Lhx7− interneurons  represent 20% of the total density of the CR+ interneuron population in the rat dorsal striatum Figure , the totWe hypothesized that these groupings of CR+ interneurons on the basis of their molecular identity and somatic size would correspond to previous qualitative observations of heterogeneity in somatodendritic structure in the CR+ interneuron population . On average, the somata of CR+/Scgn+/Lhx7− interneurons  were significantly smaller than those of CR+/Scgn−/Lhx7− interneurons  and CR+/Scgn−/Lhx7+ interneurons  . These CR+ interneurons have been described previously (Petryszyn et al., The biased rostromedial distribution of these CR+/Scgn+ interneurons in rodent striatum is particularly striking. The broad function of neurons in the striatum generally corresponds to the type of cortical input to a given territory (Hintiryan et al., 4.2Early qualitative descriptions of CR+ interneurons in the rodent dorsal striatum suggested they were “medium‐sized” (Bennett & Bolam, 4.3The functional roles performed by GABAergic CR+ interneurons within the striatal microcircuit are unclear, which is partly due to the lack of data regarding their local synaptic connectivity and electrophysiological properties (Tepper et al., 4.4In the striatum of squirrel monkeys (Parent et al., The present study provides a novel correlative approach to identify different populations of morphologically, topographically, and molecularly distinct CR+ interneurons in the striatum of both mice and rats. One of these populations, namely rostrally biased CR+/Scgn+ interneurons, was partially conserved between the rodent and primate. Our molecular characterization of striatal CR+ interneurons using Scgn and Lhx7 may also provide a useful starting point for the design of cell‐type‐selective manipulations that can be used to disentangle the specialized contributions of different populations of CR+ interneurons to activity dynamics within the striatal microcircuit.The authors declare no competing financial interests.