Incidental learning is impaired during early‐life undernutrition

Abstract

Rats were either well-nourished (control) or undernourished (PU) during the suckling and early post-weaning periods (birth to 45 days), after which all animals were fed ad libitum. From 25 to 45 days half of the rats in each group were exposed continuously in their home cases to shape stimuli (triangles and circles). Half of each of these 4 groups were given "reminders" of the stimuli through exposure for 2 h every 10-12 days from 55 to 131 days. Beginning on day 132, ability to discriminate these same visual stimuli was tested using a nonappetitively motivated version of the Lashley jumping stand technique. Discrimination learning per se was unimpaired by previous undernutrition (control and PU rats not viewing the stimuli prior to training performed equally well). However, early-life exposure led to improved learning performance only in control rats; it had no effect on the performance of PU rats (significant exposure X nutrition interaction). These findings indicate that undernutrition interfered with early "incidental learning", that is, learning about features of the environment which are not, at the time, biologically relevant. Finally, retention of the discrimination was assessed 9 weeks after the rats had attained criterion performance. There were no effects of nutrition or prior exposure on long-term memory.

In vivo effect of brain-derived neurotrophic factor on the survival of developing dorsal root ganglion cells.

“…The results presented in this study show that not only targetderived neurotrophic factors are important for the survival of early neural crest-cell derivatives, but also laminin, found in vivo around the neural tube and the developing DRG (Rogers et al, 1986). This is in full agreement with previous in vitro studies (Lindsay et al, 1985) and suggests that the presence of laminin represents a permissive condition for the survival action of BDNF.…”

Food choice and intake: towards a unifying framework of learning and feeding motivation

“…For example, in one study rats were undernourished during their suckling and early post-weaning periods and were at the same time exposed to stimuli (triangles and circles) later used in a discrimination learning task. Although they were well nourished during discrimination learning, they failed to show any benefit from the prior exposure to the stimuli, unlike control animals (well nourished throughout life) which learned the discrimination significantly faster if they had been exposed to the stimuli during their early life (Rogers et al 1986). Taken together, these findings indicate that extrinsic exploration is indeed reduced with increasing levels of feeding motivation.…”

Postnatal Growth and Mental Development: Evidence for a “Sensitive Period”

“…There are many potentially confounding variables which could account for the undoubted behavioural differences observed in formerly malnourished animals (e.g. Katz, 1982;Rogers, Tonkiss & Smart, 1985;Smart, 1987).…”