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Dynamics of Perceptual BistabilityJohn RinzelCenter for Neural Science and Courant Institute of Mathematical Sciences, New York University Tuesday, March 29, 2011 15:00-16:00, When visualizing an ambiguous scene (such as the Necker cube or the vase-faces image) one may perceive ongoing temporal alternation between the possible interpretations. Various dynamical models lead to alternating mutual exclusivity with neuronal competition implemented as reciprocal inhibition between neuronal populations. Slow negative feedback, neuronal firing adaptation or synaptic depression, sets the basic time scale (seconds) for switching. We will describe two mechanistic frameworks for the switching behavior. If the negative feedback is strong enough it can overcome dominance, and alternations occur intrinsically and periodically; noise perturbs the regularity. In an alternative, attractor-based, framework negative feedback is relatively weaker and switches are induced by noise operating on a bistable system. Statistics of the observed alternations provide constraints that favor an operating range near the transition zone between the two mechanisms. We suggest that alternation evidences a perceptual exploratory strategy with maximal sampling rate when the stimulus is most uncertain. Speaker Bio: Prof Rinzel has degrees: BS in Engineering Science (Univ of Florida, 1967), MS and PhD in Applied Mathematics (Courant Institute of Mathematical Sciences, New York University, 1968 and 1973). For most of his research career, Rinzel was at the National Institutes of Health (NIH) as a research mathematician and Chief of the Mathematical Research Branch. In 1997, he joined the faculty at New York University, jointly appointed in the Center for Neural Science and in the Courant Institute. Rinzel has developed, analyzed, and applied biophysical/computational models to design and interpret experiments involving neuronal and secretory systems. His work ranges over biophysical mechanisms at the cellular level: action potential generation, neuronal oscillations and bursting, dendritic and axonal propagation; and at the circuit level: network rhythomgenesis and synchrony; and at the perceptual level: bistability from ambiguous scenes, interval timing. He is on the editorial boards of several journals, and on the faculties of several international specialized courses in computational neuroscience. He has held visiting/adjunct appointments at numerous universities. In 2007 he was awarded the Eisenstadt Chair at the Center for Mathematical Research at the University of Montreal.
Contact: B. W. Rust Note: Visitors from outside NIST must contact Robin Bickel; (301) 975-3668; at least 24 hours in advance. |