Pe. Garraghty et N. Muja, NMDA RECEPTORS AND PLASTICITY IN ADULT PRIMATE SOMATOSENSORY CORTEX, Journal of comparative neurology, 367(2), 1996, pp. 319-326
Topographic maps in adult primate somatosensory cortex are capable of
dramatic reorganizations after peripheral nerve injuries. In the prese
nt experiments, we have deprived a circumscribed portion of the hand m
ap in somatosensory cortex of four adult squirrel monkeys by transecti
ng the median nerve to one hand, and evaluated the hypothesis that N-m
ethyl-d-aspartate (NMDA) glutamatergic receptors are necessary for the
reorganization that follows within four weeks. In one monkey, we conf
irm previous results demonstrating that the deprived cortex has regain
ed responsiveness in its expanse four weeks after median nerve transec
tion. However, in three monkeys in which NMDA receptors were concurren
tly blocked, most of the deprived cortex remained unresponsive. Thus,
much of the cortical ''recovery'' that typically follows peripheral ne
rve injury in adult monkeys is apparently dependent on NMDA receptors
and may well be due to Hebbian-like changes in synaptic strength. Perh
aps the elimination of the normally dominant inputs to ''median nerve
cortex'' permits the gradual strengthening of correlations between the
activity of the formally impotent presynaptic and deprived postsynapt
ic elements. These enhanced correlations may also have been made possi
ble by reductions in intracortical inhibition as a necessary but not s
ufficient condition. (C) 1996 Wiley-Liss, Inc.