FIG. 4.

Experimental model of analgesia on hind limbs of rabbit. (A) Insertion of acupuncture needles by Niboyet and Terral in two acupoints. (B) Measurement of the withdrawal reactions (reflex forces) with strain-gauge transducers. (C) Record of forces after painful puncture of skin with a detector equipped with strain gauges (middle line): on the left, before, and on the right, after 20 minutes of electrical stimulation of the two acupoints of the right hind limb (there were no more withdrawal reactions). (D) Implantation of a microelectrode into the nucleus parafascicularis of the thalamus of a rabbit with its head in a stereotactic frame. Bottom left shows pain signal recorded by the thalamic electrode during painful stimulation, and bottom right shows inhibition of pain signal after acupuncture stimulation.