Dysfunction of transcallosally mediated motor inhibition and callosal morphology in patients with schizophrenia

Objective: In order to assess the functional integrity of motor pathways th rough the corpus callosum (CC) in patients with schizophrenia transcallosal ly mediated inhibition (TI) of voluntary tonic EMG activity, of first dorsa l interosseus muscle following ipsilateral focal transcranial magnetic stim ulation (fTMS) was investigated. In addition thickness and length of CC wer e calculated. Method: Twelve patients suffering from schizophrenia and 12 healthy control s were investigated. CC morphology was measured in midsagittal MRI-slices. Latency and duration of TI were calculated. Results: In schizophrenics the duration of TI was significantly prolonged, whereas latencies were not. In addition, a lack of TI was found unilaterall y in three patients. Measurements of CC revealed a significantly reduction of the length and thickness in the anterior part of CC in patients. Conclusion: These findings indicate that measurement of TI could be used to detect clinical silent affection of transcallosal motor pathways in schizo phrenics. The effect of neuroleptic drugs has to be explored.