Opposing Ventral Striatal Medium Spiny Neuron Activities Shaped by Striatal Parvalbumin-Expressing Interneurons during Goal-Directed Behaviors

Medium spiny neurons (MSNs) of mice show opposing activities upon the initiation of a food-seeking lever press task. Ventromedial striatal (VMS)-MSNs are inhibited but ventrolateral striatal (VLS)-MSNs are activated; these activities mediate action selection and action initiation, respectively. To understand what input shapes the opposing MSN activities, here, we monitor cortical input activities at the cell population level and artificially reverse them. We demonstrate that the ventral hippocampus (vHP) and the insular cortex (IC) are major inputs to the VMS and VLS, both projections show silencing at the trial start time, and the vHP-VMS and IC-VLS pathways form functionally coupled input-output units during the task. Of note, the upstream IC silencing is converted to the downstream VLS-MSN activation. We find biased localization of striatal parvalbumin-expressing interneurons (PV INs) and verify PV IN-dependent feedforward architecture in the VLS. Our results reveal a distinct mode of cortico-striatal signal conveyance via feedforward disinhibition in behaving animals. [Display omitted] •We identify the striatal feedforward disinhibition in behaving animals•Striatal PV-expressing interneurons mediate feedforward disinhibition•The ventromedial striatum merely possesses PV interneurons•Opposing striatal activities are generated by biased PV interneuron distribution Yoshida et al. find that the upstream insular cortical silencing is converted to the downstream ventrolateral striatal activation in behaving animals. Parvalbumin- expressing interneurons in the ventrolateral striatum mediate this conversion through feedforward disinhibition.