Recognition memory in 3- to 4-day-old human neonates.

It has been recently established in both adult monkeys and humans that visual recognition memory, as assessed with a preferential visual fixation technique, depends on the integrity of the neural structures situated in the medial part of the temporal lobe. This kind of memory has been observed in infant monkeys not earlier than day 15. Using a familiarization technique we established that this recognition memory is present in human infants as early as postnatal day 3 when a 2-min retention interval is used. This visual recognition memory might be controlled by subcortical structures. The possibility that the medial temporal structure involved in adult visual memory is operating at birth cannot, however, be ruled out.