Barrel Cortex - The Posteromedial Barrel Subfield

The Posteromedial Barrel Subfield

The posteromedial barrel subfield (PMBSF) is a highly consistent region of the barrel field (Woolsey, 1978). Barrels of the PMBSF are the largest and most elliptical in shape and have a striking topographical organization that is identical to that of the major facial whiskers (also called myastacial vibrissae); these whiskers are organized into 5 rows of 4-7 large whiskers that run close to parallel with the bridge of the nose. (Woolsey and Van der Loos, 1970). A consideration of this morphology led Woolsey and Van der Loos to propose that the barrels of the PMBSF were the cortical correlates of the myastacial vibrissae; this is sometimes called the one-barrel-one-vibrissa hypothesis (Woolsey and Van der Loos, 1970). Thus each barrel in the PMBSF is thought to correspond with a single myastacial vibrissa on the contralateral side of the animal. In 1973 Woolsey and Van der Loos provided strong evidence for this hypothesis by selectively damaging individual whiskers in rodents at birth and noticing that when the brains of these animals were analyzed the corresponding barrel was not present.