Acquisition and retention of classical conditioning in the newborn rat.

The development of memory of a conditioned response was examined in London black rats between 0 and 4 days of age. For the conditioning, a vibrotactile stimulus paired with an electric shock was presented to the animal 80 times with an interval of 2000 msec between stimuli. The animals were retested at retention intervals of 3 min or 24 hr. The results showed that 0-, 2-, 3-, and 4-day-old rats possess a retention capacity of at least 24 hr and suggest that the emergence of memory may be task-specific.