Barrel cortex

The barrel cortex refers to the dark-staining regions of layer four of the somatosensory cortex where somatosensory inputs from the contralateral side of the body come in from the thalamus. Barrels are found in some species of rodents and species of at least two other orders. The rest of this article will focus on the 'whisker barrels' in the somatosensory cortex of rodents. Inputs from the thalamus carrying information from a given whisker terminate in discrete areas of layer IV forming anatomically distinguishable areas (barrels) which are separated from each other by areas called septa. These structures were first discovered by Woolsey and Van der Loos (1970). Recognizing that the array was similar to that of the vibrissae on the mystacial pad, they hypothesized that the barrels were the "cortical correlates of the mystacial vibrissae" and that "one barrel represents one vibrissa".