How babies stay alert, even with immature brains

Anyone who has watched a baby’s eyes follow a dancing trinket in front of them knows that babies are able to pay attention with laser focus.

But with large areas of their young brains still underdeveloped, how do they get there?

Using a pioneering approach at Yale that uses fMRI (or functional magnetic resonance imaging) to scan the brains of awake babies, a team of college psychologists shows that when they focus their attention, infants under one year of age recruit areas of their frontal cortex, a section of the brain involved in more advanced functions that were previously thought to be immature in babies. The results were published March 16 in Proceedings of the National Academy of Sciences.

“Attention is the gateway to what infants perceive and learn,” said Nick Turk-Browne, professor of psychology at Yale and lead author of the article. “Attention is the bouncer at the door, determining what information enters the brain, which ends up creating memories, language and thoughts.”

Much of the previous research related to attention in babies relied on tracking their gaze as they were presented with visual stimuli, a process that theoretically offers information about what is going on in their mind. Questions remain unanswered about which sections of the brain are involved in these responses, and how and why they get attention in this way.

Babies’ attention may depend on the sensory areas of the brain, which process stimuli such as tactile and visual stimuli and help them respond to the outside world. These regions of the brain develop earlier in infancy than regions of the frontal cortex, which are typically associated with internal functions such as control, planning, and reasoning.

The ability to use brain imaging with infants allowed us to “look behind the mirror,” for the neural origins of attention, Turk-Browne said.

For the study, they used new fMRI technology to track the neural activity of 20 babies aged 3 to 12 months, tracking which regions of their brains were activated as they focused their attention in response to a series of ‘images.

In a series of tests, babies saw a screen on which a target would appear on the left or right side. In each case, these appearances were preceded by one of three visual clues indicating where the target would appear: on the same side as the target would appear, on both sides of the screen (therefore not informative), or on the opposite side. The researchers monitored the babies’ eye movements as they performed these tasks.

As expected, the babies were much faster to move their eyes towards the target when they first presented the correct signal, confirming that the signals had focused their attention. At the same time, the researchers used brain imaging technology to see which areas of the brain were recruited during these tasks. In addition to the sensory areas of the brain, they found that activity also increased in two areas of the frontal cortex, the anterior cingulate cortex and the middle frontal gyrus, areas of the brain which, when fully developed, are involved in the control of adult attention.

“This doesn’t mean that these regions play the same role in babies as they do in adults, but it does show that infants use them to explore their visual world,” said Cameron Ellis, PhD. candidate in psychology at Yale and first author of the article.

Studying how the brain is enlisted during development “will help researchers uncover the foundations of human learning, which could one day help improve early childhood education and reveal the roots of neurodevelopmental disorders “said Ellis.

Reference: Ellis CT, Skalaban LJ, Yates TS, Turk-Browne NB. Attention recruits the frontal cortex in human infants. PNAS. 2021; 118 (12). doi: 10.1073 / pnas.2021474118

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