Corticostriatal connectivity is central for many cognitive and motor processes, such as reinforcement or action initiation and invigoration. The cortical input to the striatum arises from two main cortical populations: intratelencephalic (IT) and pyramidal tract (PT) neurons. We uncovered a new feed-forward excitatory circuit, supported by a polysynaptic motif from PT neurons to cholinergic interneurons (ChIs) to excitatory inputs, which runs in parallel to the canonical monosynaptic corticostriatal connection. This new motif conveys a delayed second phase of excitation to striatal spiny projection neurons (SPNs), through an acetylcholine-dependent glutamate release mechanism, resulting in biphasic corticostriatal signals. These biphasic signals are a hallmark of PT, but not IT, corticostriatal inputs, due to a stronger relative input from PT neurons to ChIs. These results uncover a novel feed-forward circuit mechanism by which PT activity differentially gates excitatory inputs to the striatum, with potential implications for behavior, plasticity and learning.
bioRxiv Subject Collection: Neuroscience