W. White et W. Timberlake, 2 MEALS IN THE ACTIVE PERIOD OF THE RAT BOTH ENTRAIN FOOD-ANTICIPATORY ACTIVITY, Physiology & behavior, 56(1), 1994, pp. 17-25
We examined the effect of presenting two meals at fixed times on the a
ctivity of six intact female rat. Rats maintained on a 12-12 h light-d
ark cycle were fed; ad lib, at tow randomly chosen times during the ac
tive period, and at 3 and 9 h, 1 and 7 h, and 5 and 11 h after light o
ffset. During ad lib and random feeding conditions, wheel turning prim
arily occurred during the first half of the active period. During fixe
d-time feeding conditions, wheel turning was concentrated around the t
imes of meal availability. To determine whether anticipatory wheel tur
ning during fixed-time feeding conditions was based on a circadian mec
hanism, each condition was followed by a test; light cues were omitted
and rats were deprived of food for 2 consecutive days. Wheel turning
patterns observed while a feeding condition was in effect persisted du
ring 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.