DIFFERENTIAL-EFFECTS OF NEUROPEPTIDE-Y TYPE-2 RECEPTOR ACTIVATION ON RESPONSES OF RAT VENTRAL POSTEROMEDIAL THALAMUS NEURONS TO SURROUND VIBRISSAE AND TRIGEMINAL SUBNUCLEUS INTERPOLARIS STIMULATION

Single cell recording, receptive field analysis, and microejection tec hniques were used to evaluate the effects of neuropeptide Y (NPY) type 2 (Y-2) receptor activation on the responses of vibrissae-sensitive v entral posteromedial thalamic (VPM) neurons. Activation of this recept or with the C-terminal fragment, NPY[13-36] had no significant effect on responses evoked by deflection of principal or surround vibrissae o r electrical stimulation of the trigeminal principal sensory nucleus. However, it did significantly decrease (p < 0.01) responses evoked by electrical stimulation of subnucleus interpolaris (SpI) by a mean (+/- standard error) of -31.0 +/- 8.7%). The finding that responses to sur round vibrissa stimulation were not significantly decreased by a manip ulation that did significantly attenuate SpI- evoked responses suggest s that this nucleus is not the sole source of surround vibrissae input to VPM neurons.