Circadian food-anticipatory activity: formal models and physiological mechanisms.
Rats and other species exhibit food-anticipatory activity (FAA) to daily mealtime under circadian (24 h) food access schedules. A critical review of several explanatory models indicates that hourglass clocks and associative learning processes are inadequate to explain many properties of FAA in intact and suprachiasmatic nuclei ablated rodents. A computational learning model, involving circadian clock consultation and phase memory, accounts for some but not all of these properties. An entrainment model, invoking separate, compound food- and light-entrainable oscillators, provides a more complete account of FAA. However, FAA may be simulated best by a model that combines oscillator entrainment with clock consultation and memory for circadian phase. Species as diverse as bees, birds, and mammals appear to share many features of FAA in common; differences may be explained in terms of oscillator organization and the ability to represent multiple circadian phases memorially. Physiological mechanisms of FAA are largely unknown; strategies for localization of entrainment pathways and oscillators, and a modest data base, are reviewed.
Mistlberger
R E
RE
Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada.
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D008960:Models, Psychological; D051381:Rats