Explorations of the function of the central visual pathway with visual and electrical stimulation

Understanding the relationship between neural activity and perception has long been one of the primary goals of systems neuroscience. Historically, this topic has been pursued by correlating the responses of single neurons with the presentation of sensory stimuli. Although this approach has yielded numerous insights into the organizational and functional properties of brain areas, it has yet to provide a comprehensive account of sensory processing. This is in large part due to the nature of single cell recordings. The responses of individual cells cannot reveal the complex interactions between neurons within a local population or between remote populations in different brain areas. Furthermore, correlation-based studies are typically unable to demonstrate a causal relationship between neural activity and sensory phenomena.;In light of these limitations, we have conducted a series of neurophysiological investigations of visual processing using several complementary approaches. In combination with extracellular recordings, we employ a computational model of the visual system which incorporates trends in population activity and interactions between visual areas. Our studies provide novel findings regarding the spatial processing of visual stimuli and elucidate the mechanisms underlying the evolution of spatial selectivity over time.;We additionally explore visual processing through the application of electrical brain stimulation. Electrical stimulation has long been used to manipulate the activity of distinct neural populations and can demonstrate a direct relationship between neural signals and perception or behavior. We examine the effects of transcranial magnetic stimulation (TMS), a noninvasive stimulation technique, on the function of the visual cortex. Our results demonstrate the critical role of temporal precision in sensory-evoked neural signals and lay a foundation for the optimization of TMS stimulation protocols in human research.