Causal contributions to sensory-based decision-making by cell-type specific circuits in the tail striatum
The striatum comprises distinct types of neurons giving rise to the direct and indirect basal ganglia pathways and local circuits. A large amount of work has been focusing on cell-type specific striatal circuits in the context of movement control, proposing several models on their functional roles. But it remains to be elucidated how the cell-type specific striatal circuits contribute to decision-making behavior and whether the existing models apply. Here, we investigate the causal roles of the cell-type specific circuits in the posterior tail of the dorsal striatum (TS) of mice in an auditory-guided decision-making behavior. Transient unilateral activation of the direct- or indirect-pathway striatal spiny projection neurons (dSPNs or iSPNs) both biased decisions in opposite directions. These effects, however, were not due to a direct influence on movement, but was specific to the decision period preceding action execution. Optogenetic inactivation of dSPNs and iSPNs revealed their opposing causal contributions to decisions. At the local circuit level, simutaneous optical recording and manipulation of dSPNs and iSPNs revealed their antagnizing interactions. Inactivation of PV interneurons, a common inhibitory input to both dSPNs and iSPNs, facilitated contraversive choices, supporting a causal contribution of coordinated striatal circuits. Using a neural circuit model, we further demonstrated the computational implemenation of the causal circuit mechanism. Our results indicate that while the causal roles of the cell-type specific striatal circuits in decision-making largely agree with classic models in movement control, they show decision task-related specificity involving local circuit coordination.