Two meals in the active period of the rat both entrain food-anticipatory activity.
We examined the effect of presenting two meals at fixed times on the activity of six intact female rats. Rats maintained on a 12-12 h light-dark cycle were fed: ad lib, at two randomly chosen times during the active period, and at 3 and 9 h, 1 and 7 h, and 5 and 11 h after light offset. During ad lib and random feeding conditions, wheel turning primarily occurred during the first half of the active period. During fixed-time feeding conditions, wheel turning was concentrated around the times of meal availability. To determine whether anticipatory wheel turning during fixed-time feeding conditions was based on a circadian mechanism, each condition was followed by a test: light cues omitted and rats were deprived of food for 2 consecutive days. Wheel turning patterns observed while a feeding condition was in effect persisted during meal omission. Nest and food/water compartment visits were not as sensitive to feeding times. Meals may have modified bouts of activity that are also synchronized by light-dark cycles.
White
W
W
Department of Psychology, Indiana University, Bloomington 47405.
Timberlake
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W
D000818:Animals; D001143:Arousal / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D009042:Motivation; D009043:Motor Activity / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D013493:Suprachiasmatic Nucleus / Q000502:physiology