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PHYSICS AND ASTRONOMY Science at the Edge Friday, April 23, 2010 11:30a 1400 Biomedical & Physical Sciences Bldg Refreshments at 11:15a in 1400 BPS Bldg Tatyana Sharpee Salk Institute for Biological Studies "Maximally informative input/output functions in biological networks" Many organisms rely on complex biological networks both within and between cells to process information about their environments. As such, performance of these networks can be quantified using the tools of information theory. In this talk I will describe an approach for finding input/output functions for notes in the network that would allow the network to convey the maximal amount of information about inputs drawn a given probability distribution. In particular, optimal solutions will be compared for Gaussian and more naturalistic, non-Gaussian distributions that take into account large deviations common in the natural environment. This comparison reveals the expected differences in the correlation strength between nodes as well as in the sensitivity to multiple input dimensions for individual nodes. Generally, the strength of interaction between any two nodes turns out to be related to the presence of cusps in the input/output functions, with zero interactions corresponding to the absence of cusps. This last property allows one to compute the strength of interaction between the observed and unobserved notes in the situation where the output of only some notes in a network can be monitored. I will conclude with applications of these results to retinal circuits and describe new algorithms that could improve the resolutions of retinal implants. ***To make an appointment to meet with the speaker, contact Prof. Lisa Lapidus ([log in to unmask])*** Kim Crosslan Undergraduate Secretary Dept. Physics & Astronomy Michigan State University 1312 Biomedical & Physical Sciences East Lansing, MI 48824 517-884-5531 <mailto:[log in to unmask]> [log in to unmask]