Maintenance of discrete somatosensory maps in subcortical relay nuclei is dependent on an intact sensory cortex.

Lesions of the rat barrelfield cortex drastically alter the discrete representations of the somatosensory periphery in the central nervous system. We have found that lesions placed in the parietal cortex, after the formation of barrels (postnatal day 5), can irreversibly abolish vibrissae- and extremity-related patterns of cytochrome oxidase activity in the principal sensory nucleus of the trigeminal nerve and in the dorsal column nuclei. Furthermore, abnormal patterns of enzymatic activity occur in the remaining primary somatosensory cortex and the ventrobasal nucleus of the thalamus. We conclude that cortical barrels are essential in maintenance of periphery-related discrete morphological organization in the rodent somatosensory system.