Abdisamed Abdullahi

Perceptual processing depends on a balance between excitation and inhibition (E:I), which can be studied in humans using electroencephalography (EEG). Schizophrenia is a brain disorder that is associated with altered perception and E:I balance, however it is still unclear how these impairments relate to one another. In this study, we examined the aperiodic slope of the EEG power spectrum, a metric for E:I balance in people with schizophrenia and healthy controls, across three different conditions: rest, binocular rivalry (where perception alternates spontaneously between different images presented to each eye), and a control task with the same images presented to both eyes. A steeper aperiodic slope represents relatively higher inhibition, with shallower slopes indicate relatively more excitation. We found that at rest, individuals with schizophrenia showed steeper slopes than controls, suggesting relatively higher baseline inhibition. The healthy controls showed task based modulation, with increased slope during rivalry versus rest, showing flexible E:I adjustment. On the other hand, individuals with schizophrenia demonstrated the opposite pattern, with slopes decreasing during rivalry, representing lower E:I flexibility. Both groups showed steeper slopes during the control task versus rivalry, reflecting relatively stronger inhibition. Our findings suggest that schizophrenia is indeed characterized by altered E:I balance and disrupted dynamic modulation during visual competition. Understanding these differences can provide insight into the neural mechanisms behind the altered perception in schizophrenia, and suggest aperiodic slope may be a potential biomarker for schizophrenia.