Nerve injury-induced depletion of tachykinin immunoreactivity in the somatosensory cortex of adult squirrel monkeys

Cortical immunoreactivity for tachykinin neuromodulators was evaluated 5-21 days after median and ulnar nerve transections in adult squirrel monkeys. Contralateral to the deafferentations, immunoreactive cells were reduced by about 20-40% in layer IV of the hand representation compared to the face region in area 3b. Similar deafferentations have been shown to alter the pattern of neuronal activity in the somatosensory cortex. Unresponsive regions are produced that with time become reactivated by receptive fields served by intact nerves. The immunocytochemical results reported here suggest that the presence or pattern of somatosensory input regulates content of tachykinin neuropeptides in intrinsic cortical neurons.