When the brain goes quiet: cortical silence inhibition in schizophrenia

The use of non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS), has demonstrated that patients with schizophrenia are deficient in cortical inhibition. These deficits can be due to impaired gamma-aminobutyric acid B (GABAB) activity, which may be involved in the underlying pathophysiology. Previous studies demonstrate altered cortical inhibition in relation to various GABA properties; however, the level of impairment involving GABAB receptors in patients with schizophrenia remains unclear. The purpose of this study was to examine the cortical silent period (CSP) by TMS measures in patients with schizophrenia and healthy controls. CSP duration was measured by electromyography (EMG) analysis and was the main TMS paradigm studied in 10 patients with schizophrenia and 10 healthy controls. There was no statistical significance between increased CSP duration in patients with schizophrenia and healthy controls; additionally, there were no significant findings when observing CSP duration and positive and negative symptom scale (PANSS) in patients with schizophrenia. However, the increased duration of disease was positively correlated to CSP duration in patients with schizophrenia compared to healthy controls. Our findings suggest that impaired cortical inhibition is seen as disease duration is lengthened.