the block diagram of the present invention is illustrated in fig1 . as shown therein , the subject is placed on a tilt table 1 . a number of devices could be modified to provide the required head up - tilt ( hut ) at 30 degrees or hdr at − 6 degrees . for example , a backswing exerciser ( backtrack div . pasadena calif .) could be modified as tilt table . the subject is interfaced with a stimulus apparatus 2 . two 2 mhz transcranial doppler probes of a transcranial doppler device , that could be obtained from a company called dwl , sipplingen , germany , by way of example , are fitted on a head gear placed on the temporal bones 3 , with ultrasound sample volumes focused in the main stem of major cerebral vessels , such as the rmca and lmca , respectively , by way of example . the real - time mfv measured by the tcd instrument and microcomputer 4 , could be stored on the same or a separate pc 5 for statistical analyses including fourier time series . fig2 shows a subject setup with the present invention . the subject 6 is placed on the tilt table 7 . the tcd probe on the left 8 and right ( not shown ) sides are placed on the temporal bones bilaterally , and connected to the tcd device by an electrical cord 9 . the tcd device 10 has a monitor display of the mfv trends recorded . the stimulus administration device 11 could be that for colors as described in an article by njemanze , p . c . in an article titled “ asymmetry of cerebral blood flow velocity response to color processing and hemodynamic changes during − 6 degrees 24 - hour head - down bed rest in men ”, published in journal of gravitational physiology 2005 ; 12 : 33 - 41 , by way of example . fig3 shows the functional flow chart of the present invention by way of example . the procedure begins 12 with the subject placed supine on a tilt table with 30 degrees hut . the angle for hut and hdr , could be varied according to the peculiar requirements of the experimental procedure , 30 degrees hut and − 6 degrees hdr were chosen here , by way of example . a duration of 24 hours of hdr ( 24h - hdr ) was also selected by way of example , shorter or longer duration of hdr could be necessary if required . two 2 mhz probes of an operational ftcd device are attached on both temples above the zygomatic arc 13 . the files are opened in the microcomputer of the ftcd and labeled baseline , for mfv in the rmca and lmca , respectively . all files and recordings of baseline mfv data are completed , if not 15 , further recordings are done . stimulus administration 16 , for example , color stimulation ( black , blue , white , yellow , and red ) could be carried out as described in an article by njemanze , p . c . in an article titled “ asymmetry of cerebral blood flow velocity response to color processing and hemodynamic changes during − 6 degrees 24 - hour head - down bed rest in men ”, published in journal of gravitational physiology 2005 ; 12 : 33 - 41 . simultaneously , real - time mfv in the rmca and lmca are recorded and labeled for each stimulus 17 , and labeled pre - hdr . all stimulations must be completed and recorded , if not , further stimulation and recording are done 18 . all files of mfv trends are saved and labeled for each stimulus 19 . the patient is tilted head - down to − 6 degrees 20 . the stimuli are administered at selected time intervals for a given duration 21 , for example 6h - hdr , and 24h - hdr for 60 seconds each . at each time , mfv is recorded during stimulation and marked for the particular time interval 22 . the subject is then tilted head up again to 30 degrees for post - hdr recording 23 . stimuli are administered at the selected time interval of hut 24 . duration of one hour after hdr was chosen for post - hdr recording , by way of example . all real - time mfv data are simultaneously recorded with stimulation for each selected time interval in post - hdr 25 . all files of mfv data are labeled and saved for each stimulus at each selected time interval 26 . the data could be processed on the same computer of the ftcd device , or transferred for statistical analysis including fourier time series analysis 27 and plotted for each stimulus 28 as described in an article by njemanze , p . c ., titled “ cerebral lateralization for facial processing : gender - related cognitive styles determined using fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries ”, published in laterality ; 2007 ; 12 : 31 - 49 . the same protocol could be repeated in test subjects after a drug or other interventions , to evaluate the drug - related effects . fig4 a shows the plot of spectral density estimates , overlaid for each color stimulus , for the pre - hdr rmca recording , with peaks designated as c - peaks 29 for cortical responses , and s - peaks 30 for subcortical processes , as described in detail in an article by njemanze , p . c ., titled “ cerebral lateralization for facial processing : gender - related cognitive styles determined using fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries ”, published in laterality ; 2007 ; 12 : 31 - 49 . fig4 b shows the f - peaks 31 , c - peaks 32 , and s - peaks in the rmca at 6h - hdr , for each stimulus , overlaid . the f - peaks 31 relates to reflections from the extremities and is irrelevant to the present analysis . after six hours of hdr , there is accentuation of c - peaks 32 , suggestive of cortical long - term potentiation ( cltp ). on the other hand , there is attenuation of s - peaks 33 at 6h - hdr , or subcortical long - term depression ( sltd ). fig4 c shows the f - peaks 34 , c - peaks 35 and s - peaks 36 in the rmca at 24h - hdr , for each stimulus , overlaid . the cltp and sltd evoked by the stimuli were maintained at levels similar to that at 6h - hdr . fig4 d shows the c - peaks 37 and s - peaks 38 in the rmca at post - hdr , for each stimulus , overlaid . the cltp and sltd evoked by the stimuli were maintained at levels similar to that at 6h - hdr . fig5 a shows the f - peaks 39 , c - peaks 40 , and s - peaks 41 in the lmca at pre - hdr , for each stimulus , overlaid . fig5 b shows the f - peaks 42 , c - peaks 43 , and s - peaks 44 in the lmca at 6h - hdr , for each stimulus , overlaid . in contrast , to the peaks at 6h - hdr in the rmca ( fig4 b ), there were no cltp and sltd . fig5 c shows the f - peaks 45 , c - peaks 46 , and s - peaks 47 in the lmca at 24h - hdr , for each stimulus , overlaid . compared to the peaks in the rmca ( fig4 c ), cltp and sltd were absent . fig5 d shows the f - peaks 48 , c - peaks 49 and s - peaks 50 in the lmca at post - hdr , for each stimulus , overlaid . compared to peaks in the rmca ( fig . d ), cltp and sltd were absent . a detailed description of an experiment to determine ipsilateral right hemisphere cltp and sltd , during color processing , by way of example , is set forth below . the study included 8 men of mean ± sd age of 24 . 8 ± 2 . 5 years , all were right handed as determined using a hand preference questionnaire , as described in an article by peters , m ., titled “ description and validation of a flexible and broadly usable hand preference questionnaire ” published in laterality 1998 ; 3 : 77 - 96 . visual acuity , color vision and color recognition were normal , as described in a book by frisén l ., titled “ clinical tests of vision ” published in new york : raven press , 1990 . all had normal findings for cardiovascular , neurologic and respiratory systems , and maintained the usual restrictions for cognitive studies , as described in an article by stroobant , n ., and vingerhoets g ., titled “ transcranial doppler ultrasonography monitoring of cerebral hemodynamics during performance of cognitive tasks . a review ” published in neuropsychological review 2000 ; 10 : 213 - 231 . all subjects signed written informed consent according to the declaration of helsinki , and the institutional review board approved the study protocol . the tcd scanning procedure was similar to that used in other cognitive studies , described elsewhere , in an article by njemanze , p . c ., titled “ cerebral lateralization for facial processing : gender - related cognitive styles determined using fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries ”, published in laterality ; 2007 ; 12 : 31 - 49 . briefly , tcd studies were performed using two 2 mhz probes of a bilateral simultaneous tcd instrument ( multi - dop t , dwl , singen , germany ), with sample volume placed in the rmca and lmca main stems , at a depth of 50 mm . pre - hdr recordings were made with the subject lying supine , with head and trunk elevated at 30 degrees . the subject was placed on a bed , positioned with head - down angle set at − 6 degrees . subjects consumed regular light meals , as prescribed by a dietician , and a bedpan was used for toileting . after duration of 24 hours of bed rest , subjects were returned to conditions similar to pre - hdr , with head and trunk elevated at 30 degrees , and post - hdr recording began after 60 minutes of rest . the tasks were designed by the inventor , and have demonstrated consistency and reliability with tcd ultrasonography in studies in our laboratory . the detailed design and rationale have been described elsewhere , in an article by njemanze , p . c . titled “ asymmetry of cerebral blood flow velocity response to color processing and hemodynamic changes during − 6 degrees 24 - hour head - down bed rest in men ”, published in journal of gravitational physiology 2005 ; 12 : 33 - 41 . briefly , specially adapted 3d - viewing device ( viewmaster , portland , oreg .) was painted inside with black paint , and the aperture closed to light for black and opened to direct view of light source for white . the right aperture of the device was covered , but the left aperture was open , to be backlit from reflection , from a remotely placed light source . the light source was a tungsten coil filament , of a general service lamp ran at a constant 24v and 200 w , with a color temperature of about 2980 k and approximately 20 lumens / watt . the light was projected onto a white flat screen , placed 125 cm from the lamp . the screen was placed 80 cm from the nose ridge of the subject . optical homogenous filters were placed on the reel of the viewmaster , in the light path for color stimulation . kodak wratten filters : deep blue ( no . 47b ) with short dominant wavelength ( λ ) of s λ = 452 . 7 nm ; deep yellow ( no . 12 ) with medium dominant wavelength ( λ ) of m λ = 510 . 7 nm , and red tricolor ( no . 25 ) with long dominant wavelength ( λ ) of l λ = 617 . 2 nm , were used . the excitation purity and luminous transmittance are provided in the manufacturer &# 39 ; s manual — kodak photographic filters handbook . rochester , new york : eastman kodak company , publication no . b - 3 , 1990 . for each stimulus condition , a continuous train of velocity waveform envelopes , was recorded for 60 - s simultaneously , for the rmca and lmca , respectively . the pre - hdr baseline condition was dark resting state , with the subject mute , still , and attention focused within the black visual field , with no mental or manual tasks to perform . the same condition was maintained at onset of each data acquisition , in hdr and post - hdr . the condition for data acquisition , during visual stimuli presentation , was identical to that of baseline , except for the color slides and white light . artifacts of recordings were marked and removed . velocity waveform envelopes for the relevant 60 - s intervals were first averaged in 10 - s segments , to produce six values for dark condition and each color condition , respectively . the mfv values were used for fourier analysis . ftcds is based on fourier transform algorithm . single series fourier analysis ( time series and forecasting module , statistica for macintosh , statsoft , okla . ), was applied to a dataset of 48 data points of mfv , recorded for 60 - s of stimulus duration , in eight men . the application of fourier analysis to mfv data , to determine cognitive responses , has been described in detail elsewhere , in an article by njemanze , p . c ., titled “ cerebral lateralization for facial processing : gender - related cognitive styles determined using fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries ”, published in laterality ; 2007 ; 12 : 31 - 49 . the frequencies with the greatest spectral densities ; that is , the frequency regions , consisting of many adjacent frequencies , that contribute most to the overall periodic behavior of the series for each vessel ( rmca and lmca , respectively ), were identified as fundamental ( f - peak ), cortical ( c - peak ) and subcortical ( s - peak ), peaks and were plotted as described in detail elsewhere , in an article by njemanze , p . c ., titled “ cerebral lateralization for facial processing : gender - related cognitive styles determined using fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries ”, published in laterality ; 2007 ; 12 : 31 - 49 . the latter peaks ( c - peak and s - peak ), were relevant for assessment of cortical and subcortical responses . other statistics . all analyses were performed using the software package ( statistica , statsoft , okla ., usa ). results were given as mean ± sd . analyses of variance ( anova ) was applied to spectral density estimates between two minima including the peak ( as maxima ), to examine the effects of stimulation on cortical and subcortical responses . comparison of mfv data , under different stimulation conditions was performed using anova with repeated measures , and when applicable , it was followed by a planned schaeffé contrast . the latter examined luminance effect by comparison of black versus white . a specific luminance effect , rather than non - specific light effect , would be expected to occur along an achromatic axis that runs in an opposite direction to chromatic axis , from dark baseline . a wavelength - encoding effect was considered present , when longer wavelength color ( yellow ) elicited higher spectral density estimates than shorter wavelength color ( blue ), at cortical or subcortical peaks . an energy - encoding effect was considered present , when high frequency color ( blue ), elicited higher spectral density estimates than low frequency color ( yellow ), at cortical or subcortical peaks . a wavelength - differencing effect was considered present , when wavelength - encoding effect was present in the subcortical region , and energy - encoding in the cortical region , for blue / yellow pair of colors . a reverse wavelength - differencing was considered present , when wavelength - encoding effect was present in the cortical region , and energy - encoding in the subcortical region , for blue / yellow pair of colors . a luminance sensory conflict was regarded as present , when luminance effect responsiveness occurred in two separate brain regions , simultaneously . a color sensory conflict was regarded as present , when wavelength - differencing occurred in two separate brain regions , simultaneously . cortical long - term potentiation ( cltp ) was considered present , when spectral density peaks ( c - peaks ) were significantly accentuated over pre - hdr amplitudes , and was higher than subcortical peaks ( s - peaks ). on the other hand , subcortical long - term depression ( sltd ) was considered to be present , when spectral density peaks ( s - peaks ) were significantly attenuated under pre - hdr amplitudes , and was lower than cortical peaks . to examine the effect of hdr on rmca mfv , an anova with repeated measures was performed , with the design structure of 4 × 5 : four levels of data collection times ( pre - hdr , 6h - hdr , 24h - hdr and post - hdr ), and five levels of stimulations ( black , blue , white , yellow and red ). there was a main effect of data collection times , f ( 3 , 141 ) 44 . 6 , p & lt ; 0 . 0001 . there was a main effect of stimulations , f ( 4 , 188 ) 5 . 96 , p & lt ; 0 . 001 . there was no times × stimulations interaction , ( p = ns ). planned schaeffé contrast revealed that , rmca mfv at pre - hdr ( 65 . 6 cm / s ) was significantly higher than at 24h - hdr ( 59 . 4 cm / s ; p & lt ; 0 . 0001 ) and post - hdr ( 59 . 7 cm / s ; p & lt ; 0 . 0001 ), but not at 6h - hdr ( 67 . 5 cm / s ; p = ns ). rmca mfv for the two ‘ opponent colors ’— blue ( 63 . 7 cm / s ; p & lt ; 0 . 001 ) and yellow ( 63 . 4 cm / s ; p & lt ; 0 . 05 ) were higher than black baseline ( 62 . 3 cm / s ). however , rmca mfv for white ( 62 . 8 cm / s ; p = ns ) and red ( 63 cm / s ; p = ns ) was same as baseline . similarly , anova analysis for the lmca showed that , there was a main effect of data collection times , f ( 3 , 141 )= 22 . 8 , p & lt ; 0 . 0001 . there was a main effect of stimulations , f ( 4 , 188 )= 7 . 7 , p & lt ; 0 . 0001 . there was no times × stimulations interaction ( p = ns ). planned schaeffé contrast revealed that lmca mfv at pre - hdr ( 64 . 5 cm / s ) was significantly higher than at 24h - hdr ( 59 . 4 cm / s ; p & lt ; 0 . 0001 ) and post - hdr ( 60 . 2 cm / s ; p & lt ; 0 . 0001 ), but not at 6h - hdr ( 65 . 4 cm / s ; p = ns ) lmca mfv for the colors blue ( 63 . 7 cm / s ; p & lt ; 0 . 0001 ), yellow ( 62 . 7 cm / s ; p & lt ; 0 . 05 ) and red ( 62 . 5 cm / s ; p & lt ; 0 . 05 ) was higher than for black baseline ( 62 . 3 cm / s ). however , lmca mfv for white ( 62 . 2 cm / s ; p = ns ) was same as baseline . in comparison to pre - hdr , at 6h - hdr , mfv showed a tendency to increase , but decreased at 24h - hdr and post - hdr . the tendency toward hypoperfusion at 24h - hdr and post - hdr , was more in the rmca than lmca . the latter creates a relative side - to - side difference from baseline that , may suggest a left lateralization . fig4 ( a - d ) shows the overlaid spectral density estimates , for black and colors ( blue , white , yellow and red ), at pre - hdr ( fig4 a ), 6h - hdr ( fig4 b ), 24h - hdr ( fig4 c ), and post - hdr ( fig4 d ) in the rmca . fig5 ( a - d ) shows the overlaid spectral density estimates , for black and colors ( blue , white , yellow and red ), at pre - hdr ( fig5 a ), 6h - hdr ( fig5 b ), 24h - hdr ( fig5 c ), and post - hdr ( fig5 d ) in the lmca . the f peaks were absent or significantly attenuated , due to posture in total flexion of the right elbow , which blocked blood flow wave reflections from the finger tips , as subject held the viewing device , during all study conditions , as described in an article by njemanze , p . c ., titled “ cerebral lateralization for facial processing : gender - related cognitive styles determined using fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries ”, published in laterality ; 2007 ; 12 : 31 - 49 . color responses were accentuated at subcortical ( s - peak ) and cortical ( c - peak ) peaks . a single - factor anova analysis with repeated measures was used , to determine wavelength - encoding , energy - encoding and luminance effects for the c - peaks and s - peaks , respectively . at pre - hdr , for c - peaks in the rmca ( fig4 a ), there was a main effect of energy - encoding , f ( 1 , 6 )= 5 . 7 , p = 0 . 05 . there was no main effect of luminance , ( p = ns ). at s - peaks , there was only a tendency for wavelength - encoding , f ( 1 , 6 )= 4 . 6 , p = 0 . 07 , but no luminance effect , ( p = ns ). there was wavelength - differencing in the right hemisphere . on the other hand , in the lmca ( fig5 a ), for the c - peaks , there was no main effect of wavelength - encoding , energy - encoding or luminance , ( p = ns ). at s peaks , there was a main effect of energy - encoding , f ( 1 , 6 )= 5 . 7 , p = 0 . 05 . there was a main effect of luminance , f ( 1 , 6 )= 6 . 3 , p & lt ; 0 . 05 . in both right ( fig4 a ) and left hemispheres ( fig5 a ), the c - peaks were lower than s - peaks . there was no luminance or sensory conflicts . there was no wavelength - differencing in the left hemisphere . at 6h - hdr , for c - peaks in the rmca ( fig4 b ), there was only a tendency for a main effect of wavelength - encoding , f ( 1 , 6 )= 4 . 8 , p = 0 . 07 . there was a main effect of luminance , f ( 1 , 6 )= 8 . 2 , p & lt ; 0 . 05 . at s - peaks , there was no wavelength - encoding and luminance main effects , ( p = ns ). there was no wavelength - differencing in the right hemisphere . on the other hand , in the lmca ( fig5 b ), for the c - peaks , there was no main effect of wavelength - encoding and energy - encoding . however , there was a main effect of luminance , f ( 1 , 6 )= 19 . 9 , p & lt ; 0 . 05 . at s peaks , there was no main effect of wavelength - encoding and luminance , ( p = ns ). there was a luminance sensory conflict . there was no wavelength - differencing in the left hemisphere . in the rmca , there was cltp ( p & lt ; 0 . 05 ) and sltd ( p & lt ; 0 . 05 ). on the other hand , in the lmca , cltp and sltd were absent . at 24h - hdr , for c - peaks in the rmca ( fig4 c ), there was no main effect of wavelength - encoding , ( p = ns ). there was a main effect of luminance , f ( 1 , 6 )= 9 . 7 , p & lt ; 0 . 05 . at s - peaks , there were no main effects of wavelength - encoding and luminance , ( p = ns ). there was no wavelength - differencing in the right hemisphere . on the other hand , in the lmca ( fig5 c ), for the c - peaks , there was a main effect of wavelength - encoding , f ( 1 , 6 )= 6 . 2 , p & lt ; 0 . 05 . there was a main effect of luminance , f ( 1 , 6 )= 6 . 9 , p & lt ; 0 . 05 . at s peaks , there was no main effect of wavelength - encoding and luminance , ( p = ns ). there was a luminance sensory conflict . there was no wavelength - differencing in the left hemisphere . in the rmca , there was cltp ( p & lt ; 0 . 05 ) and sltd ( p & lt ; 0 . 05 ). on the other hand , in the lmca , cltp and sltd were absent . at post - hdr , for c - peaks in the rmca ( fig4 d ), there was a tendency for a main effect of wavelength - encoding , f ( 1 , 6 )= 5 . 4 , p = 0 . 059 . there was a main effect of luminance , f ( 1 , 6 )= 6 . 9 , p & lt ; 0 . 05 . at s - peaks , there was a main effect of energy - encoding , f ( 1 , 6 )= 20 . 3 , p & lt ; 0 . 01 , but there was no luminance main effect , ( p = ns ). there was a reversed wavelength - differencing in the right hemisphere . on the other hand , in the lmca ( fig5 d ), for the c - peaks , there was a main effect of wavelength - encoding , f ( 1 , 6 )= 8 . 1 , p & lt ; 0 . 05 . there was a main effect of luminance , f ( 1 , 6 )= 8 . 9 , p & lt ; 0 . 05 . at s peaks , there was tendency for energy - encoding f ( 1 , 6 )= 4 . 8 , p = 0 . 07 . there was no luminance effect , ( p = ns ). there was a reversed wavelength - differencing in the left hemisphere . there were luminance and color sensory conflicts . in the rmca , there were cltp ( p & lt ; 0 . 05 ) and sltd ( p & lt ; 0 . 05 ). on the other hand , in the lmca , cltp and sltd were absent . this is the first published invention that provides a method for recording ltp and ltd during hdr using ftcds . the findings could be summarized for each data collection time as follows : 1 ) at pre - hdr , the cortical activity was lower than subcortical activity , there was no sensory conflict , rather there was functional specialization , with the right hemisphere involved in wavelength - differencing , and the left hemisphere in energy - encoding and luminance effect responsiveness ; 2 ) at 6h - hdr , in the right hemisphere but not left , there was cltp and sltd , there was luminance sensory conflict , and a tendency for wavelength - encoding activity in the right cortical region ; 3 ) at 24h - hdr , in the right hemisphere but not left , there were cltp and sltd , there was luminance sensory conflict , and wavelength - encoding activity in the left cortical region ; 4 ) at post - hdr , in the right hemisphere but not left , there were cltp and sltd , there was functional duplication , with a reversed wavelength - differencing and luminance effect responsiveness in both right and left hemispheres , giving rise to sensory conflict for both chromatic and achromatic detectors . the most intriguing findings of the present study are the presence of cltp and sltd , during hdr and post - hdr in the right hemisphere , which lasted for 25 hours or more , if recording was continued . this is the first noninvasive ultrasound recording of long - lasting cortical potentiation and subcortical depression in the intact human brain , reported in literature . the mechanisms underlying potentiation and depression could be deduced from what is known . it is known that for ltp and ltd to occur , there must be glutamate release as described in a book by thompson , r . f . titled “ brain : a neuroscience primer ”, 3rd edition , published in new york : worth publishers , 2000 , p . 102 - 117 . while a preferred embodiment of the present invention is described above , it is contemplated that numerous modifications may be made thereto for particular applications without departing from the spirit and scope of the present invention . accordingly , it is intended that the embodiment described be considered only as illustrative of the present invention and that the scope thereof should not be limited thereto but be determined by reference to the claims hereinafter provided .
the present invention provides a method for monitoring long - term potentiation and long - term depression , comprising placing a subject in head down rest position and monitoring in real - time cerebral mean blood flow velocity using a transcranial doppler device during psychophysiologic tasks . the method involves using fourier analysis of mean blood flow velocity data to derive spectral density peaks of cortical and subcortical processes . the effect of head - down rest at different time intervals is seen as accentuation of the cortical peaks in long - term potentiation and attenuation of subcortical peaks in long - term depression . the effect of different interventions could be evaluated for research , diagnosis , rehabilitation and therapeutic use .