What is "striosome"

The striosomes (also referred to as the striatal patches) are one of two complementary chemical compartments within the striatum (the other compartment is known as the matrix) that can be visualized by staining for immunocytochemical markers such as acetylcholinesterase, enkephalin, substance P, limbic system-associated membrane protein (LAMP), AMPA receptor subunit 1 (GluR1), dopamine receptor subunits, and calcium binding proteins. Striosomal abnormalities have been associated with neurological disorders, such as mood dysfunction in Huntington's disease, though their precise function remains unknown. Striosomes were discovered by Ann Graybiel in 1978 using acetylcholinesterase histochemistry.