State Dependent Modulation of Perception Based on a Computational Model of Conditioning
Seminar | July 18 | 12:30-2 p.m. | 560 Evans Hall
Jordi Puigbò, Universitat Pompeu Fabra (Barcelona - Spain)
The embodied mammalian brain evolved to adapt to an only partially known and knowable world. The adaptive labeling of the world is critically dependent on the neocortex which in turn is modulated by a range of subcortical systems such as the thalamus, ventral striatum, and the amygdala. A particular case in point is the learning paradigm of classical conditioning, where acquired representations of states of the world such as sounds and visual features are associated with predefined discrete behavioral responses such as eye blinks and freezing. Learning progresses in a very specific order, where the animal first identifies the features of the task that are predictive of a motivational state and then forms the association of the current sensory state with a particular action and shapes this action to the specific contingency. This adaptive feature selection has both attentional and memory components, i.e. a behaviorally relevant state must be detected while its representation must be stabilized to allow its interfacing to output systems. Here we present a computational model of the neocortical systems that underlie this feature detection process and its state-dependent modulation mediated by the amygdala and its downstream target, the nucleus basalis of Meynert. Specifically, we analyze how amygdala-driven cholinergic modulation switches between two perceptual modes, one for exploitation of learned representations and prototypes and another one for the exploration of new representations that provoked these change in the motivational state, presenting a framework for rapid learning of behaviorally relevant perceptual representations. Beyond reward-driven learning that is mostly based on exploitation, this paper presents a complementary mechanism for quick exploratory perception and learning grounded in the understanding of fear and surprise.