Inhibition of nociceptive withdrawal flexion reflexes through a dorsal column-brainstem-spinal loop

In decerebrate-decerebellate cats, dorsal column stimulation (DCst) rostral to dorsal funicular cuts, to prevent antidromic activation of afferent dorsal column fibers, inhibited spinal flexion reflexes evoked by nociceptive stimuli. The effects of DCst above the cuts were compared to those below the cuts. Our findings indicate that the analgesic effects of DCst can be attributed to activation of a DC-brainstem-spinal loop in addition to antidromic activation of spinal 'gating' mechanisms.