Role of Photoreceptors in the Synchronization of the Circadian Locomotor-Activity Rhythms with the Ld Cycle in Cockroaches (periplaneta-Americana)

WOS:A1983QG64000002International audienceThe possible role of different kind of photoreceptors in synchronization of circadian locomotor activity in cockroaches is presently still contradictory. We try to clarify the part played by the compound eyes and the ocelli with lesion and black‐varnishing experiments. The locomotor activity of isolated animals is automatically recorded in ring‐shaped cages equiped with infra‐red beams. Circadian rhythms are detected by using the Whittaker and Robinson periodogram.We obtained the following results:- Animals submitted to a shifting of their LD cycle keep the ability to synchronize with the new photocycle when their ocelli are destroyed or black‐varnished. When the eyes are destroyed or varnished, animals start free‐running or become arrhythmic.- Animals kept in IX from the eggs and submitted to a photocycle after the operation become rhythmic with ocelli destroyed or black‐varnished. With destroyed eyes, they stay arrhythmic. Only a few become rhythmic with black‐varnished eyes.- These results support Roberts, Nishiitsutsuji‐Uwo and Pittendrigh, Sokolove and Page results. The two kinds of photoreceptors are not equally powerful in synchronizing the locomotor activity rhythm with the external LD cycle. The compound eyes lead the information to the optic lobes which are considered to be circadian pacemakers. We still need to ask if they are the only circadian pacemakers in the insect brain