Reflex oral activity in decerebrate rats of different age

Rats decerebrated at different ages (4 days to greater than 100 days) were tested for a rhythmic reflex 'suckling' response and for a simple digastric reflex. The ease with which the 'suckling' response could be elicited decreased with increasing age; the time course of this change approximated to that of changing characteristics of the digastric reflex. The mean latency of the simple reflex response decreased non-linearly from 70 msec in the 4 day postpartum animal to 5 msec in the adult animal; the duration of the response also decreased from 25 msec to 10 msec but this change took place mainly between 8 and 15 days postpartum. The latency of the digastric response also shortened in animals decerebrated on day 4 and kept for 2 days. It was concluded that the observed changes in the digastric reflex occurred independently of encephalic structures.