Program#/Poster#: 758.17/AA16 Title: Competitive selection of salient stimuli in the owl optic tectum Location: South Hall A Presentation Time: Wednesday, Oct 21, 2009, 8:00 AM - 9:00 AM Authors: *S. P. MYSORE, A. ASADOLLAHI, E. I. KNUDSEN; Neurobio., Stanford Univ., Stanford, CA Abstract: We are typically faced with a complex sensory environment containing numerous stimuli. At each instant, however, only a small subset of this information is selected for attention. When not biased by top-down mechanisms, this competitive selection of stimuli for attention is driven by the relative salience of stimuli in the world. In models of attention, the selection of the most salient stimulus is accomplished by invoking a winner-take-all computation across a map of relative salience. We show that neurons in the intermediate-deep layers of the barn owl optic tectum (OTi-d, homologous to the superior colliculus in mammals) exhibit signatures of such salience-based competitive selection. When a visual stimulus (“target”) is centered in the receptive field (RF) and a second competing stimulus (“competitor”) is located far outside the RF, a majority of OTi-d neurons exhibit switch-like behavior when the strength of the competitor is systematically varied: they respond at a high level when the target is stronger than the competitor, and at a low level when the target is weaker. Across the population, the competitor strength at which this switch occurs is close to the strength of the target. Moreover, changing the strength of the target shifts the switch-point in the corresponding direction, and by the appropriate amount. Competitive selection of the more salient stimulus is also independent of stimulus feature and sensory modality, and occurs across all of space. The results demonstrate that neurons in the OTi-d select the most salient among competing stimuli, a process that is essential to attention. Disclosures: S.P. Mysore, None; A. Asadollahi, None; E.I. Knudsen, None. Keyword(s): Stimulus Selection Competitive selection Colliculus Support: SPM: Stanford University Dean\'s Postdoctoral Fellowship EIK: NIH 9 RO1 EY019179-29 [Authors]. [Abstract Title]. Program No. XXX.XX. 2009 Neuroscience Meeting Planner. Chicago, IL: Society for Neuroscience, 2009. Online. 2009 Copyright by the Society for Neuroscience all rights reserved. Permission to republish any abstract or part of any abstract in any form must be obtained in writing by SfN office prior to publication.

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