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

When a child tries to comprehend what he sees, he brain Activity appears to occur at a slower pace than in adults, which may help them continually learn new concepts.

Our brain processes sensory stimuli using networks of neurons. If a neuron receives a strong enough signal from another neuron, it transmits the signal to even more neurons, creating synchronized waves of electrical activity in which many neurons alternate between activated and silent states.

These brain waves occur at different frequencies. When a particular brain region displays a range of frequencies simultaneously, a large proportion of its neurons may synchronize with certain frequencies more than others. For example, previous research has shown that the adult visual cortex displays a wide range of frequencies when people see things, but proportionally more neurons seem to synchronize with 10 hertz wavesor cycles per second.

To see if the same applies to babies, Moritz Kester from the University of Regensburg in Germany and colleagues recruited 42 infants at 8 months of age through their parents. The team recorded the infants' brain activity using electrodes attached to their skulls while they watched dozens of friendly cartoon monsters flash on a screen for 2 seconds each for about 15 minutes.

The researchers took advantage of the fact that brain waves tend to pulse in time with rapidly flickering images to test how many neurons are synced to different frequencies in the visual parts of an infant's brain. Specifically, they turned each monster on and off at eight frequencies ranging from 2 to 30 hertz.

By analyzing brain recordings, the team found that the visual cortex generated waves of synchronized activity at the same time as the flickering cartoons. But brain waves were most excited at 4 hertz, suggesting that more neurons were synchronized to this flicker frequency than to others.

Moreover, this 4-hertz signal was present in the background even as the brain adjusted to vision at other frequencies, such as 15 hertz. “What's really interesting is that even if you stimulate at all the different frequencies, you always find a response at 4 Hz,” says Kester.

This rhythm falls in the frequency range known as theta. what was associated with the formation of new conceptstherefore, it may help infants learn from what they see. “This suggests that babies are in a constant learning mode,” says Kester.

In support of this idea, the researchers also found that 4-Hz brain waves (but not waves of other frequencies) in the visual cortex appeared to propagate to neural circuits in other brain regions involved in concept formation, suggesting that these waves convey visual information to knowledge construction.

By repeating the experiment on seven adults, the researchers confirmed previous findings that their visual brain circuits were most strongly activated by 10 Hz, and found that this frequency was present in the background regardless of the flicker speed of the cartoons.

Adults have already experienced a lot, so the visual part of their brain seems to be tuned to a higher frequency, which research shows can help them block unimportant information and focus on retrieving conceptual knowledge– says Kester.

Further research is needed to determine whether exposure to images flickering at a frequency of 4 hertz can improve infants' ability to learn new concepts, he says. Emily Jones at Birkbeck, University of London. The team hopes to learn more about this in a separate ongoing study, Koester said.