Dynamics of a sensory network of ON and OFF cells with global delayed feedback

Title: Dynamics of a sensory network of ON and OFF cells with global delayed feedback
Authors: Lefebvre, Jeremie
Date: 2010
Abstract: We study the sensory processing features of a network built of ON and OFF cells with global delayed feedback. We investigate the response of neural populations to spatio-temporal forcing, mimicking that found in most sensory systems. The network architecture is inspired from the physiology of the electrosensory lateral-line lobe (ELL) of the weakly electric fish, where we describe the collective behavior of populations in the pyramidal cell layer. ON pyramidal cells receive sensory inputs directly, while OFF cells receive a mirror image of the stimuli via an interneuron, inverting their response. The two opposed responses propagate upstream where they recruit the inhibitory feedback pathways. To enhance the distinction between the sub-populations, different baseline firing rates are implemented (to which we refer as asymmetry). As a novel approach to this problem, we model the neural circuit using a system of neural field equations, where the connectivity is determined solely by all-to-all and non-topographic inhibitory recurrent connections. Motivated by numerical and experimental results on the electrosensory system, we determine the conditions for which global rhythmic activity states appear in response to spatially organized stimuli. Novel responses to localized pulses are shown in the steady state regime, where the feedback connections interfere with local ON and OFF activities. These effects are systematically compared to the dynamics of a noisy Integrate-And-Fire network sharing the same architecture and parameters with the neural field formulation. Lastly, we investigate the impact of intrinsic cellular adaptation on oscillatory dynamics. Together these results establish the theoretical basis for input driven transitions to rhythmic states in delayed feedback networks with realistic neural populations.
URL: http://hdl.handle.net/10393/30128
CollectionTh├Ęses, 1910 - 2010 // Theses, 1910 - 2010
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