The role of the cingulum bundle in self-mutilation following peripheral neurectomy in the rat

Peripheral neurectomy in rats is followed by self-mutilation of the denervated zone (autotomy), which is assumed to represent an index of pain or dysesthesia associated with deafferentation. This study examines the role of the cingulum bundle in mediating autotomy behavior. Rats were given bilateral injections of 1 microliter of 0.5% bupivicaine (a local anesthetic) or saline into the cingulum bundle immediately prior to, and on Days 1, 7, 14, and 21 after, sectioning the sciatic and saphenous nerves. Bupivicaine injections into the cingulum produced a significant delay in the onset of self-mutilation and reduced the overall degree of autotomy. Furthermore, the delayed onset of autotomy exceeded the duration of the anesthetic block produced by bupivicaine.