Lower perturbational complexity index after transcranial magnetic stimulation in schizophrenia patients

Abstract

© 2025 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Background: 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. Methods: 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). Results: 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. Conclusions: 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.

This work was supported by the following grants: ‘Instituto de Salud Carlos III’ (PI-22/00465), and Gerencia Regional de Salud de Castilla y León (GRS-2685/A1/2023) and partially supported by the “Ministerio de Ciencia e Innovación (MICINN)” (grant ID PID2020-117751RB-I00), and “Fundació La Marató de TV3” (grant ID 202219-30-31), “MICIU/AEI/10.13039/501100011033” and by “ERDF A way of making Europe” through the project PID2022-138286NB-I00, and by “CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN)” through “Instituto de Salud Carlos III“ co-funded with ERDF funds and by the ERA-Net FLAG-ERA JTC2021 project ModelDXConsciousness (Human Brain Project Partnering Project). Two research training grants by the ‘Consejería de Educacion ´ – Junta de Castilla y Leon´ ’ and the ‘European Social Fund’ (VA-223-19 and VA-183-18) were respectively awarded to PhD candidates RBRS and IFL. GMM is in receipt of a FI-2022 grant from “Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR)”. These funding sources had no other role than that of providers of financial support.

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