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172. Intra-individual variability in the retinal response in schizophrenia
Increased intra-individual variability (IIV) in response to stimuli may reflect processing deficits in schizophrenia that are concealed in typical between-group analyses of mean responses. Previous studies have demonstrated increased variability in behavioral (Rentrop et al., 2010) and magnetoencephalographic (Shin et al., 2015) responses within the disorder. Although abnormal retinal cell functioning in schizophrenia has been previously demonstrated, the trial-to-trial variability within retinal functioning remains unclear. In the current study, we investigated IIV of the retinal response to light stimuli in people with schizophrenia (n=25) and in healthy control subjects (n=24) using flash electroretinography (fERG). Between-group differences were observed under conditions of greater light intensity. We are generating intraclass correlation coefficients (ICC) for each subject, reflecting variability across 30 trials in the 100 milliseconds following light flashes. These analyses are conducted separately for a condition in which a between-group difference emerged, as well as for a condition of weak light intensity where between-group differences were not observed but where the strength of the response in patients was related to negative symptoms. We will report on between-group comparisons of ICCs, in addition to relationships between ICC values and symptom clusters in the schizophrenia group.