Our large sample size allowed us to identify 17 distinct cell types in the human caudate, including rare interneuron and non-neuronal populations not previously identified in single-cell studies such as a recent single-cell atlas of the brain57. These include a population of cholecystokinin/vasoactive intestinal polypeptide-expressing neurons detected in small numbers in animal models but previously not detected in the human striatum,33 a population of calretinin-expressing neurons, knowledge of which has been extremely limited,33 and a small cluster of vascular smooth muscle cells, a cell type which has recently been linked to neurovascular coupling;58 a recent study linked neurovascular coupling with chronic alcohol exposure in mice.59
