Bodian Seminar: POSTPONED
Alessandra Angelucci, MD, Ph.D.
Ophthalmology & Visual Sciences
University of Utah
“Organization and function of feedback connections in early visual processing”
In the primate visual cortex, information travels along feedforward connections through a hierarchy of areas. Neuronal receptive fields in higher areas become tuned to increasingly complex stimulus features, via convergent feedforward inputs from lower areas.
In turn, anatomically prominent feedback connections send information from higher to lower areas. Feedback connections have been implicated in many important functions for vision, including attention, expectation, and visual context, yet their anatomy and function have remained unknown. This is partly due technical difficulties of selectively labeling and manipulating the activity of feedback neurons. To overcome these technical limitations, we have used novel viral labeling and optogenetic approaches to investigate the anatomy and function of feedback connections between the secondary (V2) and the primary (V1) visual areas of primates. We find evidence for the existence of multiple anatomically and functionally distinct feedback channels.
Moreover, our results point to a fundamental role of feedback in early visual processing, controlling the spatial resolution of visual signals, by modulating receptive field size, the perceptual sensitivity to image features, by modulating response gain, and contributing to contextual modulation in V1.