Mutual entrainment of bilaterally distributed circadian pacemaker.

Abstract

The interactions between the bilaterally distributed components of the circadian system that controls the locomotor activity rhythm of the cockroach Leucophaea maderae were investigated in a series of surgical lesion experiments. Complete excision of 1 optic lobe (either right or left) or its surgical isolation from the CNS had no effect on the animal''s ability to free-run in constant darkness nor was there any indication, as judged by postoperative .tau. [time] values, of any difference between left and right lobe pacemakers. These surgical procedures consistently resulted in a significant increase in .tau. over preoperative values while optic nerve section had no effect on .tau.. Probably, the left and right pacemakers in the 2 optic lobes are mutually coupled and the compound pacemaker''s period is shorter than either of its constituent pacemakers. The integrity of either compound eye is sufficient to assure entrainment of both left and right pacemakers.