Interactions between perinatal and neonatal associative learning defined by contiguous olfactory and tactile stimulation

Tactile stimulation of the neonate, as performed by the mother during and a fter delivery, has been described as an effective unconditioned stimulus du ring early ontogeny (Leon, 1987; Ronca & Alberts, 1994). The present experi ments examined the interaction between perinatal and neonatal learning dete rmined by the explicit association between alcohol odor and vigorous body s timulation of the perinatal organism. In Experiment 1, rat fetuses were exp osed to either alcohol or saline 10 min prior to cesarean delivery. The alc ohol administration procedure here employed was sufficient to provide senso ry contamination of the amniotic fluid but avoid fetal alcohol intoxication . Pups in the two prenatal treatments later experienced the smell of alcoho l, tactile stimulation, or both stimuli explicitly paired or unpaired. Othe r postnatal groups were composed of pups that had no explicit experience wi th either experimental stimulus. Pups subjected to alcohol odor in utero di splayed more overall motor activity in response to that odor than saline co ntrols. The increased motor responses were further potentiated in pups that experienced additional postnatal alcohol odor paired with tactile stimulat ion. In Experiment 2, pups were exposed to alcohol in the amniotic fluid 10 or 30 min prior to birth. As previously demonstrated the memory acquired i n utero appears highly dependent upon contingency between exposure to this particular scent and delivery procedures. Pups in bath prenatal treatment g roups were then exposed to alcohol odor paired or unpaired with tactile sti mulation. Some control animals received no further experience with either s timuli. Those pups exposed to alcohol odor paired with tactile stimulation both pre- and postnatally later showed maximum motor activity elicited by t he odor of alcohol. The results support the notion of fetal associative lea rning comprising alcohol's chemosensory cues and behaviorally activating st imuli. Furthermore, the conditioned response under analysis is potentiated whenever neonates are reexposed to contingent presentations of the elements that defined the original associative memory. (C) 1999 Academic Press.