Gain Modulation by Corticostriatal and Thalamostriatal Input Signals during Reward-Conditioned Behavior

Abstract

Summary: The cortex and thalamus send excitatory projections to the striatum, but little is known about how these inputs, either individually or collectively, regulate striatal dynamics during behavior. The lateral striatum receives overlapping input from the secondary motor cortex (M2), an area involved in licking, and the parafascicular thalamic nucleus (PF). Using neural recordings, together with optogenetic terminal inhibition, we examine the contribution of M2 and PF projections on medium spiny projection neuron (MSN) activity as mice performed an anticipatory licking task. Each input has a similar contribution to striatal activity. By comparing how suppressing single or multiple projections altered striatal activity, we find that cortical and thalamic input signals modulate MSN gain and that this effect is more pronounced in a temporally specific period of the task following the cue presentation. These results demonstrate that cortical and thalamic inputs synergistically regulate striatal output during reward-conditioned behavior. : Lee et al. show that excitatory corticostriatal and thalamostriatal projections regulate striatal activity and gain in mice performing a Pavlovian reward conditioning task. They find that gain modulation by these projections is more evident in the period between cue and reward presentation. Keywords: Corticostriatal, thalamostriatal, secondary motor cortex, parafasicular thalamus, integration, multiplication, summation