How attention helps you remember

A new study from MIT neuroscientists sheds light on a neural circuit that makes us likelier to remember what we're seeing when our brains are in a more attentive state.

The team of neuroscientists found that this circuit depends on a type of brain cell long thought to play a supporting role, at most, in neural processing. When the brain is attentive, those cells, called astrocytes, relay messages alerting neurons of the visual cortex that they should respond strongly to whatever visual information they are receiving.

The findings, published this week in the online edition of the Proceedings of the National Academy of Sciences, are the latest in a growing body of evidence suggesting that astrocytes are critically important for processing sensory information, says Mriganka Sur, the Paul E and Lilah Newton Professor of Neuroscience at MIT and senior author of the paper.

Sur's lab has been studying astrocytes for about five years, as part of a longstanding interest in revealing the functions of different cell types in the cortex. The star-shaped cells were first discovered and named 150 years ago, but since then, ''it's been a mystery what they do,'' says Sur, who is a member of MIT's Picower Institute for Learning and Memory and director of the Simons Center for the Social Brain at MIT.

Lead authors of the paper are graduate student Naiyan Chen and research scientist Hiroki Sugihara. Other authors are research scientist Jitendra Sharma, postdocs Gertrudis Perea and Jeremy Petravicz, and technical assistant Chuong Le.

Attention strengthens response
In this study, the researchers focused on what astrocytes do when the brain is stimulated to pay attention to a specific visual stimulus. When someone is paying close attention to something, the nucleus basalis - a structure located deep within the brain, behind the eyes - floods the brain with a neurotransmitter called acetylcholine. Some of this acetylcholine targets astrocytes in the visual cortex.