When infants attempt to comprehend their surroundings, their brain activity reveals slower rhythms compared to adults, aiding them in grasping new concepts.

Our brains utilize a network of neurons to interpret sensory input. When a neuron receives a sufficiently strong signal from its neighbor, it transmits that signal to other neurons, generating synchronized waves of electrical activity that alternate between activated and silent states.

These brain waves manifest at various frequencies. A specific brain area may show a greater proportion of neurons synchronized to one frequency over others if it exhibits a range of frequencies simultaneously. For instance, prior research indicates that the adult visual cortex displays a diverse range of frequencies when individuals are observing stimuli, but in higher proportions, more neurons synchronize with the waves at a frequency of 10 hertz.

To determine if the same holds true for infants, Moritz Kester from the University of Regensburg in Germany along with his colleagues enlisted 42 eight-month-olds via their parents. The researchers recorded the infants’ brain activity with electrodes affixed to the scalp, exposing them to dozens of friendly cartoon monsters for about 15 minutes, each monster flashing for two seconds.

The team relied on the fact that brain waves tend to oscillate in sync with rapidly flickering images, enabling them to assess the number of neurons synchronized to various frequencies within the infants’ visual cortex. Each monster was toggled on and off at eight different frequencies ranging from 2 to 30 hertz.

Analysis of the brain activity data revealed that the visual cortex produces waves of synchronized activity in response to the flickering cartoons. However, the most prominent signals emerged at four hertz, indicating greater synchronization with this flicker frequency than with others.

Moreover, this 4-hertz signal was consistently present even when the brain was exposed to flickering at higher frequencies, such as 15 hertz. “What’s particularly intriguing is that regardless of the different frequencies presented, a response at 4 hertz was always observed,” comments Kester.

This rhythm falls within a frequency band known as theta, which is associated with the formation of new concepts, potentially facilitating learning for young children as they observe their environment. “It suggests that infants are in a specific learning mode,” Kester explains.

Researchers supporting this theory further discovered that there were no 4-hertz EEG signals in the visual cortex, nor EEG signals at other frequencies, suggesting a broader neural circuit involvement in other brain areas related to concept formation.

Repeating the experiment with seven adults confirmed prior findings that visual brain circuits are predominantly activated by the 10 hertz frequency, which was also found to persist in the background despite varying speeds of the cartoon flickering.

Given adults’ extensive experiences, it appears that the visual sections of their brains are fine-tuned to respond to more frequent stimuli. They block irrelevant information and concentrate on acquiring conceptual knowledge, states Kester.

Further research is necessary to establish whether exposure to 4 hertz flickering images can enhance infants’ capacity to learn new concepts, according to Emily Jones at Birkbeck, University of London. The team is hopeful to gain further insights in an ongoing study, Kester added.