Cosyne 2007 Workshops
February 26-27, 2007
The Canyons, Utah
Speaker Name
Harel Shouval, Department of Neurobiology and Anatomy the University of Texas Medical School in Houston, TX
Talk Title
Learning Reward Timing using Reinforced Expression of Synaptic Plasticity
Talk Abstract
The ability to represent time is an essential component of cognition but its neural basis remains unknown. It is commonly believed that the underlying cellular mechanisms reside in high order cortical regions but recent studies show sustained neural activity in primary sensory cortices that are reward dependent and can represent the learned time of expected reward. Although extensively studied in both behavioral and electrophysiological studies, a general theoretical framework capable of describing the elementary neural mechanisms used by the brain to adaptively learn temporal representations is lacking. Here we present two different models by which the brain can learn temporal representations through a simple theoretical framework predicated on reward dependent expression of synaptic plasticity. One model asserts that temporal representations are stored within the lateral connections between neurons, while the other model assumes that temporal representation is accomplished by single neuron conductances. We demonstrate that in both cases reward modulated plasticity is sufficient to learn these representations. We implement our models computationally to explain reward-time learning in the primary visual cortex (V1) and suggest experimentally verifiable predictions. We also show how a population of such neurons can estimate the reward time given the spiking activity of the network, and how the error of this estimate scales with the reward time.
