CRCNS:US-lsrael Research Proposal: To Elucidate Fundamental Mechanisms of Transformed Saliency Map to

The neural bases of sensory stimulus selection, an essential function for attentional and adaptive behavior, will be investigated by this collaborative project in barn owls, a specialized stimulus localizer species. While a topographic representation of relative stimulus strength and behavioral relevance across visual and auditory space has been demonstrated in the barn owl's optic tectum (OT), how the information is conveyed to downstream decision-making centers for proper control of stimulus driven behaviors is unknown in barn owls, as well as in other species. The main goal of the proposed research is to understand the read-out mechanisms of the midbrain map in the ascending midbrain-to-forebrain pathway, along which a transformation involving abolishment of a topographic representation of spatial location is observed. Barn owls offer a strong advantage for investigating these questions, because of their robust and well-studied visual and auditory representations across brain regions and because a robust auditory saliency map has been shown in the barn owl. This study aims at answering the question of how behaviorally relevant sensory signals are selected and encoded to induce stimulus location driven perceptual and behavioral responses while others are ignored. Through simultaneous recordings of midbrain, thalamic and forebrain regions, the hypothesis that topographic representation of salient stimuli is translated into a non-topographic representation of salient stimuli for both visual (Aim 1) and auditory (Aim 2) salient stimuli will be tested in both anesthetized and behaving animals. Computational modeling describing network processing and coding will be used for further testing hypothesis and detailed description of network and coding mechanisms underlying transformational coding of stimulus selection (Aim 3). Preliminary results support feasibility of proposed approaches. This collaborative computational project will contribute intellectual merits and broader impact of widening view and understanding of neural coding and network mechanisms underlying stimulus selection by a transformational coding scheme from midbrain to forebrain, fundamental for selective attention and perception of salient stimuli across species. Innovative simultaneous recordings of midbrain and forebrain regions of anesthetized and awake animals, and interdisciplinary physiological, behavioral and computational approaches will be implemented. In addition, training opportunities and publication goals for undergraduate, graduate and postdoctoral fellows will enhance their visibility and career plans.