The present study was undertaken to verify further the participation of motor cortex(MCtx)in the somatosensory area Ⅱ(SII)emanating descending modulation of thalamic intralam-inar nuclei(ILN).Neuronal responses in ILN to noxious stimulation of the superficial peroneal nerve were ex-tracellularly recorded in 34 cats.The effects of electrical stimulating SII on nociceptive responsesof neurons in ILN before and after lesion of MCtx were observed and compared.It was shown that electrical stimulation of SII obviously inhibited the nociceptive responsesin the majority of neurons recorded(11/13)in ILN in the cats with MCtx intact(P<0.05).Afterlesion of MCtx the inhibitory effect still remained(n=10

P<0.05)

but weakened to a certainextent compared with that before lesion.In the animals with the lesion involving MCtx and theunderlying subcortical structures electrical stimulating SII facilitated the nociceptive responses ofILN neurons(n=7

P<0.05).The results further support the idea that SII emanating descending modulation on ILN is inpart fulfiled via MCtx.