OPTIC LOBE CIRCADIAN PACEMAKER SENDS ITS INFORMATION TO THE CONTRALATERAL OPTIC LOBE IN THE CRICKET GRYLLUS-BIMACULATUS

The bilaterally paired optic lobe pacemakers of the cricket Gryllus bi maculatus are mutually coupled. In the present study we recorded the n eural activity conveyed from the brain toward the optic lobe with a su ction electrode to examine the coupling signals. The results demonstra ted that the brain efferents to the optic lobe encode the circadian in formation: Both in constant light (LL) and constant darkness (DD), the neural activity of brain efferents showed a clear circadian rhythm wi th a nocturnal peak. Since the rhythm survived the severance of the co ntralateral optic nerve but disappeared when the contralateral optic l obe was removed, it is apparent that the rhythm originates from the co ntralateral optic lobe. The amplitude of the rhythm was greater in LL than in DD, suggesting that light affects the amplitude of the rhythm. This was confirmed by the fact that the light-induced response was un der circadian control, being greater during the subjective night. Thes e data suggest that the bilaterally paired optic lobe pacemakers excha nge circadian information as well as light information. The data are a lso consistent with the results of previous behavioral experiment.