Cerebellar pathways There are pathways that have been proposed to explain the non-motor dysfunctions seen in<unk> . A leading view of<unk>  is the dysmetria of thought hypothesis, which proposes that the non-motor deficits in<unk>  are caused by dysfunction in the cerebrocerebellar system linking the cerebral cortex with the cerebellum. The normal cerebellum is now thought to be responsible for regulating motor,<unk>  and emotional behaviors. When there is some type of damage to the cerebellum, this regulation is affected, leading to deregulation of emotional behaviors. This effect has been compared to dysmetria of movement, which describes the motor dysfunctions seen after cerebellar lesions. These ideas build upon earlier theories and results of investigations indicating that the cerebellum is linked with the frontal orbital cortex, limbic system, and reticular structures. It was proposed that these circuits are involved with emotional regulation, such that damage to this circuit would result in behavioral dysfunctions such as hyperactivity, apathy, and stimulus-seeking behaviors. Connections lead from the cerebral cortex (including sensorimotor regions as well as<unk> ly relevant association areas and emotion-related limbic areas) to the cerebellum by a two-stage feedfoward system. The pathway starts in the layer V neurons of the cerebral cortex that project via the cerebral peduncle to the neurons of the anterior portion of the pons (the basis pontis). The pontine axons projects via the contralateral middle cerebellar peduncle, terminating in the cerebellar cortex as mossy fibers. The feedback circuit from the cerebellum to the cerebral cortex is also a two-stage system. The cerebellar cortex projects to the deep cerebellar nuclei (the corticonuclear microcomplex). The deep nuclei then project to the thalamus, which in turn projects back to the cerebral cortex. This cerebrocerebellar circuit is key to understanding the motor as well as the non-motor roles of the cerebellum. The relevant<unk>  areas of the cerebral cortex that project to the cerebellum include the posterior parietal cortex (spatial awareness), the supramodal areas of the superior temporal gyrus (language), the posterior parahippocampal areas (spatial memory), the visual association areas in the parastriate cortices (higher-order visual processing), and the prefrontal cortex (complex reasoning, judgment attention, and working memory). There are also projections from the cingulate gyrus to the pons. The organization of these anatomical pathways helps clarify the role the cerebellum plays in motor as well as non-motor functions. The cerebellum has also been shown to connect brainstem nuclei to the limbic system with implications for the function of the neurotransmitters serotonin, norepinephrine, and dopamine and the limbic system. The connection with the limbic system presumably underlies the<unk>  symptoms of<unk> . Cerebellar anatomy It has been suggested that specific parts of the cerebellum are responsible for different functions. Mapping of the cerebellum has shown that sensorimotor, motor, and somatosensory information is processed in the anterior lobe, specifically in lobules V, VI, VIII A/B. The posterior lobe (notably cerebellar lobules VI and VII) is responsible for<unk>  and emotional functions. Lobule VII includes the vermis in the midline, and the hemispheric parts of lobule VIIA (Crus I and Crus II), and lobule VIIB). This explains why<unk>  occurs with damage to the posterior lobe. In the study of Levisohn et al. children with<unk>  showed a positive correlation between damage to the midline vermis and impairments in affect. The authors hypothesized that deficits in affect are linked to damage of the vermis and fastigial nuclei, whereas deficits in cognition are linked to damage of the vermis and cerebellar hemispheres. These notions were consistent with the earlier suggestion (by psychiatrist Robert G. Heath), that the vermis of the cerebellum is responsible for emotional regulation. The deep nuclei of the cerebellum also have specific functions. The interpositus nucleus is involved with motor function, the dentate nucleus with<unk>  functions, and the fastigial nucleus with limbic functions. It has been shown that phylogenetically the dentate nuclei developed with the association areas of the frontal cortex, supporting the view that the dentate nucleus is responsible for<unk>  functions. Lateralization There have been studies that show laterality effects of cerebellar damage with relation to<unk> . Language in the cerebellum seems to be contralateral to the dominant language hemisphere in the frontal lobes, meaning if the language is dominant in the left hemisphere of the frontal lobes, the right side of the cerebellum will be responsible for language (see Tedesco et al. for a discussion of lack of lateralization). Lateralization is also observed with visuospatial functions. One study found that patients with left cerebellar lesions performed more poorly on a visuospatial task than did patients with right cerebellar lesions and healthy control adults. It has also been shown that lesions of the right cerebellum result in greater<unk>  deficits than lesions of the left hemisphere.
Cerebellar cognitive affective syndrome
Post-encephalitic parkinsonism
Dejerine–Roussy syndrome
Dopamine-responsive dystonia
Bickerstaff brainstem encephalitis
Wernicke–Korsakoff syndrome
Paraneoplastic cerebellar degeneration
Parkinson-plus syndrome