Haluk Ogmen
Department of Electrical & Computer Engineering
Center for Neuro-Engineering and Cognitive Science
University of Houston
Houston, TX 77204-4005

Abstract
The primate visual system contains extensive anatomical feedback, including significant excitatory connections. Furthermore, information processing at different neural loci is highly nonlinear and exhibits a broad range of latencies. A fundamental question is to understand how the visual system maintains its real-time stability in the presence of nonlinear positive feedback and delays. We will address this problem from the perspective of a REtino-COrtical Dynamics (RECOD) theory according to which the real-time dynamics of visual processes unfolds in three phases: (i) a “feed-forward dominant” phase where strong afferent signals travel to higher cortical areas allowing the read-out of the input and energizing the feedback loops; (ii) a “feedback dominant” phase during which the afferent signal decays to a lower plateau value and the feedback, or re-entrant, signals establish perceptual synthesis, and (iii) a “reset phase” that is initiated when inputs change; during the reset phase the feedback signals receive a fast and transient inhibition so as to allow the dominance of the afferent signals (feed-forward dominant mode) which deliver the new input. We will map this theory to the architecture of the visual system (parvo- and magnocellular afferent pathways and dorsal and ventral cortical pathways) and compare its predictions to double dissociation phenomena in visual masking.

Supported by grants R01-MH49892 from NIH and BCS-0114533 from NSF.

Speaker
Haluk Ogmen received B.Sc.A. and Ph.D. degrees in electrical engineering from Université Laval, Québec, Canada in 1983 and 1988, respectively. He joined the University of Houston in 1988 as an assistant professor. He spent the 1995-1996 academic year at the Smith-Kettlewell Eye Research Institute in San Francisco, CA as a visiting scientist. Presently he is Professor and Chair of the Department of Electrical and Computer Engineering and the Director of the Center for Neuro-Engineering and Cognitive Science at the University of Houston. He received several teaching awards including the College of Engineering W.T. Kittenger Outstanding Teacher award in 1998. He received the junior and senior faculty research awards from the College in 1994 and 2003, respectively. He was recently selected as a fellow of the Hanse-Wissenschaftskolleg (Hanse Institute for Advanced Study) in Germany. His research interests are in the areas of vision, visual psychophysics, neuro-engineering, and computational neuroscience. His research has been supported by grants from the National Institutes of Health (NIH), National Science Foundation (NSF), Texas Advanced Research and Technology Programs, and NASA-JSC. He published in a broad range of journals --including Consciousness and Cognition, Nature, Neural Computation, Neural Networks, Psychological Review, Vision Research-- that reflect the inter-disciplinary nature of his research. He is co-author of two forthcoming books on visual perception to be published by MIT Press and Oxford University Press.