Institution: University of Nevada Reno
Talk Title: Anomalous visual cortical excitability in Schizotypy
Abstract: One of the most robust biomarkers in psychiatry is the sensory hypo-excitability seen in individuals with schizophrenia, especially to auditory stimuli, suggesting that they are less sensitive to incoming sensory information than non-clinical individuals. However, subclinical individuals exhibiting schizophrenia-like traits (schizotypy) report more illusions in the Pattern Glare Test (PGT), consistent with behavioral hyperexcitability and being more sensitive to sensory (visual) input. This throws into question the use of sensory biomarkers to assess symptom load subclinically. We examined cortical visual excitability in schizotypy to assess its use as a biomarker of symptom load. Participants completed the Schizotypal Personality Questionnaire Brief Revised (SPQ-BR) and were categorized into high schizotypy (SPQ > 87) and a control group (SPQ-BR = 50-70). Participants completed the PGT, and electroencephalography (EEG) was recorded while they viewed grating patterns that reversed contrast at 6Hz. As expected, individuals with high schizotypy reported more illusions from the PGT than controls (Cohens d = 1.01). They also produced larger visual steady-state responses compared to controls (Cohens d = 0.3). High schizotypy exhibited visual cortical hyperexcitability, consistent with the higher number of illusions seen in the PGT, but inconsistent with what we see in diagnosed schizophrenia. This divergent multisensory profile in schizotypy may be crucial in helping us understand how the underlying pathology changes with symptom progression.