Hippocampus, striatum and beyond: interweaving motivation with action, memory and perception - Cyriel Pennartz

In this talk I will begin with addressing different kinds of motivation and its sources, from homeostatic drives to exploration of novel environments and the pursuit of cues and contexts that are predictive of beneficial outcome. The topic of cue- and context-based reward predictions will be deepened by looking at the systems neurophysiology of the hippocampus and ventral striatum, which have been implicated in episodic memory and learned motivated behavior, but which are nonetheless intimately connected. Next to the role of this system in place-reward associative learning we will consider new data on "remapping" phenomena in these two structures, suggesting a novel mechanism for incorporating motivational signalling in high-dimensional, model-based coding.
A further source of afferent input to the striatum stems from the prefrontal cortex, and we will especially scrutinize the orbitofrontal cortex, which has been linked to flexible representations of stimulus-outcome associations. In the course of associative learning, groups of neurons discriminate progressively better between stimuli that are coupled to either a positive (rewarding) outcome or a negative (punishing) outcome. Because the mechanism underlying this development of spike-pattern discriminability is unknown, we investigated the causal role of NMDA receptors in this form of plasticity, using tetrodes combined with local perfusion of an NMDA receptor blocker in rat orbitofrontal cortex. The results confirm that NMDA receptors are instrumental in this reward-dependent form of neural plasticity, and shed light on their role in neural synchronization.
A final topic will be to ask how pervasive the effects of motivation and reward-dependent learning are throughout the brain, taking primary visual cortex as a case study. We will discuss 2-photon imaging evidence showing that reward information not only impinges on primary sensory areas, but also has long-lasting effects on visual tuning curves of specific cell assemblies.

Prof. Dr. Cyriel M.A. Pennartz
Dept. of Cognitive and Systems Neuroscience
Center for Neuroscience
Research Priority Program Brain & Cognition
University of Amsterdam