Study finds brain's learning processes linked with female reproductive cycle

New Delhi, Nov 12 (PTI) Brain processes involved in helping one learn may naturally fluctuate in line with the female reproductive cycle and be linked with molecule changes due to dopamine production, according to a new study in mice, findings from which could potentially explain how the neurochemical helps in learning in humans.

"There is a growing realisation in the medical community that changes in the oestrogen levels are related to cognitive function and, specifically, psychiatric disorders," said Christine Constantinople, a professor in New York University's center for neural science and senior author of the study published in the journal Nature Neuroscience.

"Despite the broad influence of hormones throughout the brain, little is known about how these hormones influence cognitive behaviours and related neurological activity," Constantinople said.

Researchers performed experiments with mice, which involved providing the animals with audio cues carrying information about water availability.

Learning abilities of the mice were seen to be enhanced when oestrogen levels were increased, which the authors said could be because the female sex hormone boosts dopamine activity in the brain's 'reward centre', making reward signals stronger.

However, when oestrogen activity was suppressed, the hormone was curbed in its ability to regulate dopamine and therefore, learning was seen to be diminished in the animals.

The result pointed to a potential link between hormone levels and symptoms of neuropsychiatric disorders, the researchers said.

"All neuropsychiatric disorders show fluctuations in symptom severity over hormonal states, suggesting that a better understanding of how hormones influence neural circuits might reveal what causes these diseases," Constantinople said.

The team added that cognitive activity was seen to be unaffected by oestrogen activity, and that effects were specific to learning abilities.

The authors wrote, "(Natural oestrogen production) predicts dopamine reuptake and RPE (reward prediction errors) signalling, and causally dictates the impact of previous rewards on behaviour." "Our results provide a potential biological explanation that bridges dopamine's function with learning in ways that better inform our understanding of both health and disease," lead author Carla Golden, a postdoctoral fellow at New York University said. PTI KRS KRS APL APL