Suckling and arousal in the rabbit: activity of neurones in the cerebral cortex

Behavioural and electrocorticographic studies during suckling in the rabbit are contradictory. As the patterned discharge of neurones in the cerebral cortex reflects an animal's level of arousal, a study was made of the activity of 47 neurones during suckling to resolve this dispute. No consistent relationship was established between mean frequency of discharge and suckling. In contrast, for 41/47 cells the modal interspike interval in the pre-suckling period, 49.9 (6-120) msec; mean (range), showed a significant (p less than 0.01; Student's t test) lengthening in suckling, 72.5 (14-240) msec. Six neurones stopped firing in suckling (less than 0.05 Hz) so a modal interval could not be calculated. In post-suckling both the modal interval and rate of discharge for all neurones were not significantly different from pre-suckling values. These findings confirm the view that reflex milk ejection is associated with arousal in rabbits.