Carly J. Leonard, Ph.D. - US grants

Project Summary Diagnosis and treatment of mental health disorders frequently lack precision, with the occurrence of multiple diagnoses within an individual and high variability in treatment effectiveness across individuals. Such difficulties speak to the need for better understanding of individual differences, which is the central goal of the Research Domain Criteria (RDoC) approach. A primary objective of this project is to use inspiration from the PI?s previous schizophrenia research to investigate clinically-relevant dimensions of individual variation in information acquisition during active vision. Understanding individual differences during active vision is important because the processing more closely mirrors everyday life, in which the world is not briefly presented and eye movements are not constrained. Moreover, this research moves beyond the classic top-down/bottom-up dichotomy of visual attention, which is blurred when considering bottom-up visual input is ?controlled? by decisions about where and when to saccade next. The proposed experiments specifically consider the tradeoff involved in saccade initiation at any given point in time. On one hand, a saccade disrupts any perceptually-coherent representations of a visual scene that have built up in retinotopically-organized visual cortex. On the other hand, a saccade provides the benefits of foveal vision and cortical magnification to information from a new location in the visual field. This coordination of perceptual organization and saccadic decision is examined using search for a closed contour in a field of Gabors, a task at which people with schizophrenia are impaired. Recent research has also suggested that people with schizophrenia may hyperfocus on a narrow range of space, a tendency which may occur in other clinical conditions such as autism as well. The current project aims to better understand this variation in the typical population, specifically its effects on peripheral processing and saccadic decisions in a contour integration task. The role that eye movements play in this type of perceptual organization has not been previously examined. Pilot data from the typical population shows widespread individual differences in saccadic behavior during this contour integration task. Individuals who let information accumulate longer by delaying a saccade perform the task with less eye movements overall. In this project these individual differences will be examined in relation to other clinically-relevant measures, including working memory and personality measures. The stability of these measures within individuals will be examined across contexts that change the optimality of extended information accumulation from peripheral vision. EEG/ERP methods will measure neural signals of early visual processing preceding eye movement initiation to identify differential activity that predicts saccadic time and destination, both across individuals and across trials within individuals. In line with the RDoC initiative goals, this research will help understand dimensions of individual variability that are relevant to everyday functioning and mental health disorders. The long-term goal of this work is to improve knowledge about the etiology of mental illnesses by characterizing dimensions of individual variability within the typical population.