Inhibition of nociceptive responses of wide-dynamic-range neurons by peripheral nerve stimulation

Of 107 neurons from the sacral and coccygeal levels of the spinal cord in anesthetized intact rats examined, 62 wide-dynamic-range (WDR) neurons that responded to noxious heating of the tail were recorded. On the basis of their inhibitory responses through A-beta or A-delta afferent fibers to noxious stimulation, these neurons were classified into one of the following three types: Type I--neurons inhibited only by A-beta afferent nerve impulses; Type II--neurons inhibited only by A-delta afferent nerve impulses; Type III--neurons inhibited by both. The present results are compared with previously reported behavioral results.