Lower perturbational complexity index after transcranial magnetic stimulation in schizophrenia patients

Informational integration and differentiation of the cortex can be tested by methods such as the perturbational complexity index (PCI) combined with TMS-induced activity perturbation. The PCI is obtained by stimulating the cortex with TMS and measuring the resulting spatiotemporal cortical responses with high-density EEG. We have compared PCI between 26 patients with schizophrenia (15 males), 15 of them First Episode (FE) (7 males), and 22 healthy controls (12 males). Values of PCI were significantly lower in patients with schizophrenia, as well as in FE considered alone. There was no significant relation between anomalous self-experiences or symptoms and PCI values in the patients: PCI values were unrelated to treatment doses or illness duration. Our data suggest that spatiotemporal cortical responses to TMS pulses are reduced in patients regarding variability or spatial extension, which could imply a lower capacity for sustaining informational complexity. [Display omitted] •Informational processing of the cortex tested by Perturbational Complexity Index.•Perturbational complexity index combined with TMS-induced activity perturbation.•Values of PCI were significantly lower in patients with schizophrenia.•No significant relation between anomalous self-experiences or symptoms and PCI.•Spatiotemporal cortical responses to TMS pulses are reduced in schizophrenia patients.