The experiment was carried out on rats. Unit d1scharges of NRM were recorded extracellularly with glass microelectrode.Before the lesion of the head of N.Caudatus

15 NRM neurons were recorded.The stimulation of the hindlimb areas of SM could obviously activate NRM neurons

the spontaneous discharges were increased to 59.06±25. 35 % (P<0.05) and the nociceptive responses were obviously inhibited to-46. 61±14.78 (P<0.01) at 0minute after stopping stimulation

Both effects lasted for 15 minutes

and then gradually returned to original level.After the lesion of the head of N. Caudatus

the effects of the stimulation of the hindlimb areas of SM on 19 NRM neurons were clearly decreased.The spontaneous discharges were increased to only 6. 9±21. 46 % and thenociceptive responses were inhlbited only - 4. 57±11.08 % at 0 minute after stopping stimulation

even the nociceptive responses were slightly increased in 5 - 30 minutes

The difference between the two groups was statistical significance

The value of the difference was about 42 % (P<0.05 ) at 0 minute and lasted 30 minutes.It suggests that the effects of stimulating SM on NRM may be transmitted by the head of N. Caudatus in the extrapyramidal system