title: Effects of localized low-temperature pulses on the cockroach circadian pacemaker.
abstract: The hypothesis that the circadian pacemaker that controls the activity rhythm in the cockroach, Leucophaea maderae, is composed of mutually coupled optic lobe oscillators was investigated using localized low-temperature pulses. Following section of one optic tract cooling the intact optic lobe for 6 h (7.5 degrees C) beginning at activity onset consistently caused a phase delay of several hours. Cooling the neurally isolated lobe had little or no effect. The results suggested the low-temperature phase delays the rhythm via a phase shift in an oscillator in the optic lobe. To determine if optic lobe oscillators were coupled, low-temperature pulses were given to one optic lobe of intact animals. If the treated lobe was isolated by optic tract section 4 days after the pulse, the rhythm (driven by the untreated lobe) was delayed; but if the tract was cut 0.5 h after the pulse the phase shift was prevented. The interaction between the optic lobes in intact animals was also found to reduce the delay caused by a low-temperature pulse. These results suggest the cockroach circadian pacemaker is composed of two mutually coupled optic lobe oscillators.
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001921:Brain / Q000502:physiology; D002940:Circadian Rhythm; D003058:Cockroaches / Q000502:physiology*; D003080:Cold Temperature; D008297:Male; D009043:Motor Activity / Q000502:physiology*