Effects of olanzapine on cerebellar functional connectivity in schizophrenia measured by fMRI during a simple motor task.
BACKGROUND
According to current theories, schizophrenia results from altered connectivity in brain circuits for fundamental cognitive operations. Consequently, the poorly understood mechanisms of neuroleptic treatment may be explainable by altered functional interactions within such networks. The 'cognitive dysmetria' model hypothesizes that one key structure in these circuits is the cerebellum. To investigate the effects of olanzapine on cerebellar functional connectivity (CFC), a seed-voxel correlation analysis (SVCA) was used in a functional magnetic resonance imaging (fMRI) study of a simple finger-tapping task.


METHODS
fMRI scans were obtained from six schizophrenic patients under both drug-free and olanzapine-treated conditions and from a matched control group of six healthy subjects at corresponding time points. SVCAs were performed for anatomically and functionally standardized seed voxels in the anterior cerebellum. SVCA results were then processed by three different randomization analyses.


RESULTS
The analyses revealed that olanzapine caused widespread changes of CFC, including prominent changes in prefrontal cortex and mediodorsal thalamus. Significant changes in motor structures were found after subtractions within both groups and may thus indicate repetition effects rather than drug effects. Olanzapine 'normalized' the patients' CFC patterns for the right, but not for the left cerebellum.


CONCLUSIONS
Even for a simple motor task, olanzapine affects functional interactions between the cerebellum and many non-motor brain regions, including elements of the 'cognitive dysmetria' circuit. Altogether, our findings suggest that olanzapine has a stronger differential effect on neural activity in prefrontal cortex and thalamus than in motor structures.
Stephan
K E
KE
Computational Systems Neuroscience Group, C. & O. Vogt Brain Research Institute, Heinrich-Heine-University, Düsseldorf, Germany.
Magnotta
V A
VA
White
T
T
Arndt
S
S
Flaum
M
M
O'Leary
D S
DS
Andreasen
N C
NC
D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D001569:Benzodiazepines; D002531:Cerebellum / Q000002:abnormalities / Q000187:drug effects* / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000187:drug effects*; D009483:Neuropsychological Tests; D000077152:Olanzapine; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use*; D017397:Prefrontal Cortex / Q000002:abnormalities / Q000503:physiopathology; D012559:Schizophrenia / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology*; D012720:Severity of Illness Index
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D010890:Pirenzepine; D000077152:Olanzapine