direct projections to other basal forebrain structures, including notably the cholinergic substantia inomiata.39,48,49 Thus, this TAC3 MSN archetype could represent the genesis of an additional pathway, along with the direct and indirect pathways, for cortico-striatal signals to reach the cortex. As with the DS cell types, the regulatory code controlling these cell-type-specific VS gene expression patterns will likely hold the keys to molecular access points.
