Erika G. Gisel

Nocturnal feeding behavior in the neonatal rat.

Abstract The possibility that neonatal rats (5 days old) exhibit independent feeding rhythms has been examined by studying nipple attachment latencies on anesthetized dams during the day and during the night. Latencies were found to be significantly shorter at night. The results were not affected by the lighting cycle of the dam used for latency testing, nor by the degree of fullness of her mammary glands. We conclude that 5 day-old rats are capable of independent rhythmic behavior and that their feeding preference is intrinsically nocturnal. A corrolary of these findings is that the usual pattern of suckling during the day must be imposed on the pups by the mother.

Swimming as a method for assessing motor cortex integrity in the rat

Rats were tested on 6 measures of swimming behavior 1, 2 and 4 weeks after sham operations or bilateral motor cortex lesions that damaged the forelimb areas and axons controlling the axial musculature. Rats with lesions performed more forelimb kicks and showed larger body angles than control animals. Number of hindlimb kicks and speed were within normal limits. Thus, some measures of swimming can be affected by small motor cortex lesions that spare the hindlimb projections.