Farran Briggs, Ph.D.

Critical to our comprehension of the brain is an understanding of how neuronal circuits, or the connections between neurons in the brain, underlie perception and behavior. The goals of the laboratory are to understand how neuronal circuits in the early visual system encode and process visual information and how spatial attention modulates these activities. There are four main projects that are currently underway in the laboratory. The first aims at understanding the mechanism by which visual attention modulates the activity of neurons and circuits in the early visual pathways. We have demonstrated that attentional modulation of neurons in the primary visual cortex depends critically on the match between the feature selectivity of individual neurons and the features required for successful task completion. We continue to explore the mechanisms of attention at the granular and circuit level in order to develop a more comprehensive understanding of visual attention. The second project in the lab is designed to elucidate the functional role of the corticogeniculate feedback circuit in visual perception. We have shown that corticogeniculate neurons connecting the visual cortex with the visual thalamus in the feedback direction are morphologically and physiologically diverse. We have utilized an innovative combination of virus-mediated gene delivery and optogenetic techniques to show that corticogeniculate feedback controls the timing, precision, and variability of thalamic responses to incoming visual information. Ongoing experiments will further define how corticogeniculate feedback regulates the flow of information about distinct visual features in the environment. The third project explores physiological changes that occur in the visual thalamus following removal of retinal input, as can occur in many diseases of the eye. Related work will also explore the role of the visual thalamus and extrastriate visual cortex in visual perception following damage to primary visual cortex that occurs during stroke. Finally, a fourth project in the lab aims to decode visual responses under more natural conditions in freely moving subjects. Together, these projects utilize combinations of innovative methods to better understand the neuronal basis for visual perception in both health and disease.