Internal Noise and Visual Working Memory Deficits in Schizophrenia

Abstract

Individuals with schizophrenia exhibit core deficits in visuospatial working memory and basic visual processing. While much is known about these areas independent of each other, it remains unclear whether dysfunction in early visual processing contributes to downstream deficits in working memory. One putative mechanism by which visual inefficiencies may lead to working memory impairment is through heightened noise during visual perception, which would limit the precision and increase the variability with which working memory representations are encoded. The present series of behavioral studies utilize an established psychophysical model of visual perception to show that individuals with schizophrenia can be characterized by higher levels of internal noise relative to matched healthy controls. Furthermore, individual differences in internal noise were related to visual working memory variability in those with and without schizophrenia as well as traits associated with schizophrenia vulnerability in a non-clinical group of college students. A final study tests the potential utility of noninvasive electrical current stimulation for modulating internal noise in those with schizophrenia with the aim to improve visual working memory. Collective findings underscore the link between perception and working memory encoding and offer a novel computational strategy for identifying common pathophysiological mechanisms of the working memory dysfunction in schizophrenia.