Babies’ brains ‘tick’ more slowly than ours, which may help them learn

When a baby tries to understand what he has seen, his brain activity seems to check at a slower rate than in adults, which can help them learn new concepts continuously.

Our brain treats sensory stimuli using neural networks. If a neuron receives a sufficiently strong signal from another neuron, it still transmits the signal to more neurons, producing synchronized waves of electrical activity where many neurons alternate between activated and silent states.

These brain waves occur at different frequencies. When a given brain region simultaneously displays a range of frequencies, a higher proportion of its neurons can synchronize with certain frequencies more than others. For example, previous studies show that the adult visual cortex has a wide range of frequencies when people see things, but proportionally, no more neurons seem to synchronize with waves at 10 Hertz, or cycles per second.

To find out if the same applies to infants, Moritz Köster at the University of Regensburg in Germany and his colleagues recruited 42 8 months old babies, via their parents. The team recorded the brain activity of infants – using electrodes placed on their cellar – while they were looking at dozens of flash cartoon monsters on a screen for 2 seconds each, for about 15 minutes.

Researchers have used the fact that brain waves tend to spend in time with flashing images quickly, offering a way to test the number of neurons synchronizing with different frequencies in the visual parts of the infant’s brain. More specifically, they sparkle each monster in a way and extinguished at eight frequencies, ranging from 2 to 30 hertz.

By analyzing the brain recordings, the team found that the visual cortex produced waves of synchronized activity in time with flickering caricatures. But brain waves were the most drawn on 4 Hertz, which suggests that more neurons synchronized with this flickering frequency than with others.

In addition, this 4-hertz signal was present in the background even when the brain adapted to seeing it vacillating at other frequencies, such as 15 Hertz. “What is really interesting is that even if you stimulate in all the different frequencies, you always find the 4-hertz answer,” explains Köster.

This rhythm is in a frequency band known under the name of Thêta, which was linked to the formation of new concepts, so it can help infants learn from what they see. “This suggests that infants are in constant learning mode,” says Köster.

In support of this idea, researchers also found that brain waves at 4 Hertz, but not those in other frequencies, in the visual cortex seemed to spread to neural circuits in other brain regions involved in the formation of concepts, which suggests that these waves transmit visual information in fields of strengthening knowledge.

By repeating the experience of seven adults, the researchers have confirmed previous results that their visual brain circuits are most strongly activated by a frequency of 10 Hertz and discovered that this frequency was present in the context, regardless of the rate at which the caricatures were sparkled.

Adults have already experienced a lot, so that the visual part of their brain seems to be set to check at a higher frequency, which, according to studies, can help them block unimportant information and focus on recovery of conceptual knowledge, explains Köster.

Other studies are necessary to determine whether exposure to flickering images to 4 Hertz could improve the ability of infants to learn new concepts, explains Emily Jones in Birkbeck, University of London. The team hopes to know more about this in a separate study, explains Köster.