EEG Multiscale Complexity in Schizophrenia During Picture Naming

We aimed to investigate changes in non-linear brain dynamics of patients with schizophrenia during cognitive processing. As expected, controls had fewer naming errors than patients. Regarding EEG complexity, the interaction between Group, Task and ROI indicated that patients showed higher complexity values in right frontal regions only at rest, where no differences in complexity between patients and controls were found during the naming task. EEG complexity increased from rest to task in controls in left temporal-parietal regions, while no changes from rest to task were observed in patients. Finally, differences in complexity between patients and controls depended on the frequency bands: higher values of complexity in patients at rest were only observed in fast bands, indicating greater heterogeneity in patients in local dynamics of neuronal assemblies. Consistent with previous studies, schizophrenic patients showed higher complexity than controls in frontal regions at rest. Interestingly, we found different modulations of brain complexity during a simple cognitive task between patients and controls. These data can be interpreted as indicating schizophrenia-related failures to adapt brain functioning to the task, which is reflected in poorer behavioral performance.This research was supported by Junta de Andalucía (Biomedical and Health Science Research Project PI-0410-2014 to MS and PI-0386-2016 to S. Iglesias-Parro); and Ministerio de Economía, industria y competitividad (PSI2015-65502-C2-1-P to MB and PSI2015-65502-C2-2-P to CG-A)