The Left Striato-pallidal Hyperactivity Model of Schizophrenia

Positron emission tomography (PET) was used to demonstrate an abnormally high ratio of region-to-whole brain blood flow (CBF) in the left globus pallidus of neuroleptic-naive patients. This finding has been replicated in PET image averaging studies and in a separate cohort of schizophrenic patients and controls. Schizophrenic patients also demonstrate abnormal orienting to right visual hemispace, consistent with an abnormality of the left hemisphere. Both of these findings could be due to reduced dopaminergic modulation of the left ventral striatum, resulting in striato-pallidal hyperactivity and hemineglect. Schizophrenic patients are thought to be similar to patients with hemiparkinsonism involving the left striatum, with the difference that only non-motor parts of the striatum are involved. Neuroleptic medications may work by restoring symmetry to striatal function.