Investigating the Effect of Arousal on Visual Processing

PROJECT SUMMARY/ABSTRACT How do states of arousal affect how we process visual information? Whether driven by a momentary startle response or by lower-frequency fluctuations in mood or energization, arousal states play a key regulatory role in our daily lives and exert widespread modulatory effects on neural information processing. Despite the ubiquitous role that arousal levels likely play in modulating cognition, the precise mechanisms by which arousal state alters neural representations remain unclear. One of the prevailing theories for arousal posits that the locus-coeruleus norepinephrine system alters representations by modulating the input-output gain of neural systems. The visual system serves as an ideal test bed for testing this theory, as decades of vision science has provided a deep understanding of the mechanisms that locally regulate the gain of response in early visual cortex. Furthermore, well-validated measurement methods are available for quantifying response properties of vision-related neural systems noninvasively in humans. In the proposed project, we leverage our knowledge of the neural computations within the visual system to directly test the hypothesis that emotional arousal alters representations via changes in the gain of representation. To do so, the proposed project will use a combination of state-of-the- art functional neuroimaging methods paired with psychophysics to examine the influence of arousal on fundamental properties of the human visual system: orientation, spatial frequency and contrast processing. Taken together, these visual features play a substantial role in determining our ability to visually represent and interact with the environment; any changes in these responses with arousal would have potentially substantial impact on what we can and cannot see at any given moment. By revealing the manner in which visual representations vary with arousal levels, our results will not only provide constraints for computational models of vision and arousal, but also have the potential to establish a theoretical and empirical framework for testing models of arousal that could eventually generalize to other systems.