Reduced cerebellar inhibition in schizophrenia: a preliminary study.
OBJECTIVE
Postmortem and structural imaging studies suggest that patients with schizophrenia have disrupted cerebellar activity. It has been speculated that these abnormalities mediate disorganized thought processes and psychosis. The authors' goal was to use transcranial magnetic stimulation to measure cerebellar inhibition, a proxy of cerebellar activity, as the principal output of the cerebellum is inhibitory.


METHODS
Cerebellar inhibition was accomplished by delivering a magnetic cerebellar conditioning stimulus 5-15 msec before a magnetic test stimulus to the motor cortex. The cerebellar conditioning stimulus inhibits the size of the motor evoked potential produced by the test stimulus by approximately 50%. Ten patients with schizophrenia and 10 healthy comparison subjects completed the cerebellar inhibition protocol.


RESULTS
Patients with schizophrenia demonstrated significant deficits in cerebellar inhibition compared with healthy subjects.


CONCLUSIONS
The authors conclude that deficits in cerebellar inhibitory activity in schizophrenia may be the result of an abnormality in the cerebellum or disrupted cerebellar-thalamic-cortical connectivity.
Daskalakis
Zafiris J
ZJ
Schizophrenia Program, Centre for Addiction and Mental Health, University of Toronto, Ont. M5T 1R8, Canada. Jeff_Daskalakis@camh.net
Christensen
Bruce K
BK
Fitzgerald
Paul B
PB
Fountain
Sarah I
SI
Chen
Robert
R
D000328:Adult; D002531:Cerebellum / Q000503:physiopathology*; D003213:Conditioning, Psychological / Q000502:physiology; D004576:Electromyography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008280:Magnetics; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000503:physiopathology; D011689:Purkinje Cells / Q000502:physiology; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D013788:Thalamus / Q000503:physiopathology