The role of the cerebellum in schizophrenia

Abstract

For many years the cerebellum has been considered to serve as a coordinator of motor function. Likewise, for many years schizophrenia has been considered to be a disease that primarily affects the cerebrum. This review summarizes recent evidence that both these views must be revised in the light of emerging evidence about cerebellar function and the mechanisms of schizophrenia. Evidence indicating that the cerebellum plays a role in higher cortical functions is summarized. Evidence indicating that cerebellar abnormalities occur in schizophrenia is also reviewed. These suggest interesting directions for future research.

Figure 1

CCTCC

Figure 2

A composite representation of cerebellar regions active in various tasks in healthy subjects, based or PET studies conducted at our research center Surface was created from the MR image of a single subject, and is viewed from the posterior. The left side is cut away to show a coronal view of the folia and corpus medulare. Anatomical regions have been colored corresponding to group results for the functional tasks. For each task listed below the activity of a baseline task has been subtracted to isolate the task of interest. For instance, for the task activating long-term memory for a word list, the baseline task was reading words. The cutaway of the surface shows the MR image of the folia at that location and the activations below the surface. For some tasks more than one region is active. so there are multiple regions labeled for that task. In all these studies different and appropriate task-dependent cortical regions were activated in addition to the cerebellum, providing support for the importance of the CCTCC as a distributed brain circuit and Model 3 of cerebellar function described above. 1. Verbal recall of a well-learned story(2) 2. Long-term memory for a word list (3) 3. Creating an empathetic narrative - Theory of Mind task (5) 4. Verbal recall of a recently learned word list (3) 5. Recall of pictures of faces (7) 6. Externally paced finger tapping (unpublished data) 7. Acquisition of eyeblink conditioning (unpublished data)

Figure 3

A composite representation of cerebellar regions with lower activity in patients with schizophrenia than in controls. Results for 1 - 7 are from double subtraction studies (for each group the activity of a baseline task has been subtracted before the groups were compared) analyzed with a randomization analysis. Results for 8 were for fMRI analyzed where the group-by-condition contrasts compare each group’s activations with appropriate baseline conditions. 1. Verbal recall of a well-learned story (1) 2. Long-term memoryfor a word list (4) 3. Creating an empathetic narrative - Theory of Mind task 4. Verbal recall of a recently learned word list (4) 5. Recall of pictures of faces {unpublished data) 6. Externally paced finger tapping (unpublished data) 7. Acquisition of eyeblink conditioning (unpublished data) 8. Working memory for manipulated sets of letters (6), outlined in red.

Figure 4

Pontine cerebellar Circuits