How rat pups learn to avoid potential danger

LONDON - Scientists from New York University have uncovered changes in the brains of helpless rat pups that make them learn about potential danger.

They say that if similar mechanisms operate in the brains of young monkeys and human infants, it may help explain why they remain strongly attached even to abusive mothers.

Lead researcher Regina Sullivan of New York University’s Langone Medical Centre exposed rat pups to certain odour paired with electric shocks.

The study showed that only when pups reach about 10 days old do they become capable of associating odours with negative stimuli.

Sullivan had previously found that odours associated with their mother suppress the release of stress hormone corticosterone in rat pups.

The new study showed that corticosterone suppression in turn reduces levels of the neurotransmitter dopamine in the brain’s “fear centre”.

The researchers found that in 8-day-old pups exposed to shock-paired odours, genes involved in the release of dopamine were relatively inactive, which inhibited them from avoiding shock-linked odours.

However, these genes were much more active in 12-day-old pups, which learned to avoid the shock-linked odours.

When the team injected 8-day-olds with corticosterone, the activity of the dopamine-associated genes rose, and the pups learned to avoid the shock-paired odours just like older rats.

These changes in brain physiology may be necessary in a species like rats, in which the young are born helpless.

“Dopamine was the only thing really correlated with what the pup was learning,” New Scientist quoted Sullivan as saying.

She said that initial attachment to the mother is vital for survival, but later, once the animals start to explore for themselves, it becomes important to replace blind attachment with the ability to learn about potential dangers.

The study appears in journal Nature Neuroscience. (ANI)