Discovery of a thalamic integrator for action reinforcement

Abstract

The pursuit and acquisition of rewards is essential for survival. The input nucleus of the basal ganglia, the striatum, facilitates the selection, execution, and reinforcement of reward obtaining actions. The contributions of excitatory input from cortical regions and the influence of dopaminergic signaling on corticostriatal synapses to these vital functions has been studied extensively. A relative underappreciation for thalamic contributions to striatal signaling has consequently excluded this major excitatory input from basal ganglia models of action selection and reinforcement. I investigated the contributions of the rostral intralaminar thalamic nuclei to striatal-mediated action sequence performance using a combination of ex vivo physiological and in vivo behavioral assays. In the present dissertation, I characterize mechanisms by which this thalamic projection interacts with striatal neuronal populations and modulates dopaminergic signaling to sculpt output activity. I further identify that the rostral intralaminar nuclei causally contribute to action execution in the pursuit of rewards. This work serves to further understanding of how thalamic inputs participate in action selection and reinforcement.