Inner drumbeats

Our brain is never truly at rest — even in moments of relaxation, billions of neurons remain active, generating complex rhythmic patterns known as brain waves. These rhythms vary in frequency and are traditionally labeled with Greek letters: delta, theta, alpha, beta, and gamma. Each type is thought to be associated with different mental states and brain functions, from deep sleep to active thinking and creativity. For instance, the slowest delta waves oscillate between approximately 0.5 and 4 hertz and dominate during deep sleep, while on the other end of the spectrum, high-frequency gamma waves — ranging from 30 to 100 hertz and beyond — are linked to intense mental activity, attention, and consciousness. These mysterious electromagnetic oscillations were first recorded in the early 20th century by German psychiatrist Hans Berger, who discovered the alpha rhythm, thus laying the foundation for the entire field of neurophysiology. Today, research into brain rhythms underpins a wide array of cutting-edge technologies — from diagnosing epilepsy and sleep disorders to developing neural interfaces that let us control devices with nothing but our thoughts. Yet many fundamental questions remain unanswered. Why do certain rhythms dominate during rest, while others emerge under cognitive strain? Can we consciously influence these rhythms to boost memory, attention, or creative thinking? Scientists believe that uncovering the secrets of these brain waves may be the key to unlocking the full potential of the human mind.

When two brains synchronize: scientific evidence of interbrain coupling during communication

When talking with another person, we rarely consider the complex processes occurring in our brains. However, recent scientific research confirms that during a conversation, individuals’ neural rhythms can become synchronized — a phenomenon known as “brain-to-brain entrainment.”

A recent study published in Scientific Reports demonstrated how brain activity between speakers and listeners aligns during communication. Researchers used electroencephalography (EEG) to record the electrical activity of two participants engaged in a dialogue without visual contact. Taking turns telling stories, the participants exhibited significant synchronization in their brainwave rhythms.

The results revealed synchronization across various frequency ranges — from slower (delta and theta) to faster rhythms (alpha and beta). A primary factor in this synchronization is the speech signal itself, as the brain automatically adjusts to the acoustic characteristics of speech. Interestingly, however, part of this interbrain synchronization occurred independently of auditory perception, highlighting the role of social interaction itself.

These findings support the hypothesis that communication is not merely an exchange of auditory signals but a complex process of mutual neural tuning, where two separate brains begin functioning as a single cognitive system.

Researchers from the University of Helsinki conducted an experiment to determine whether people’s brains can synchronize even when interacting solely through a computer screen, without physical presence. Pairs of friends or partners played a collaborative racing game: one controlled the car’s speed, the other its direction. Participants were in separate rooms and could only communicate through in-game actions. Their brain activity was recorded using EEG.

In my opinion, this is less strange than synchronization during conversation, because there is clearly a connection between perceived visual and auditory patterns and the synchrony in the activation of visual attention and the motor cortex, which very likely correlates with brain rhythms.

Such studies underpin a new field in neuroscience known as “two-person neuroscience.” Researchers emphasize that to fully understand the mechanisms of speech communication and social interactions, it is insufficient to study brain activity in isolation from interpersonal contexts.

Thus, seemingly ordinary conversations reveal a remarkable new dimension — as unique manifestations of synchronized neural activity between individuals.

The future of this research offers broad possibilities, not only for neuroscience but also for applied fields such as communication psychology, education, and rehabilitation. A deeper understanding of interbrain synchronization mechanisms could help improve social interactions, optimize learning processes, and even develop novel therapeutic methods for communication and social behavior disorders.

Is it possible to control attention using neurofeedback and alpha brain rhythms?

Imagine you could shift your attention from the left side of space to the right, and vice versa, using only your thoughts — without even moving your eyes. It might sound like science fiction, but recent research demonstrates that this is entirely feasible through neurofeedback based on alpha brain rhythms. Interestingly, electromagnetic stimulation of neuronal ensembles here was controlled with a fixed gaze, whereas classical stimulation occurs when gaze shifts toward the left or right visual hemifield.

Brain waves in the alpha range (8–12 Hz) are typically observed when a person is at rest with their eyes closed. Scientists have long noted that variations in alpha wave intensity across different brain areas correlate with where a person is focusing their attention. For instance, when attention is directed to the left visual field, alpha activity in the right hemisphere decreases, and vice versa. However, until recently, it wasn’t clear whether alphа changes cause attentional shifts or is merely a byproduct. In this case, the focus is on controlling and modifying the amplitude of the rhythm, rather than adjusting its phase.

In a study published in the journal Neuron in 2020, researchers from MIT — Yasaman Bagherzadeh and her colleagues — used magnetoencephalography (MEG)-based neurofeedback to test whether directly manipulating alpha rhythms could control attention.

Participants were tasked with mentally modifying alpha wave activity in either the left or right parietal cortex while looking at the center of a screen, thereby altering the contrast and clarity of the image presented. Crucially, subjects were not provided any explicit instructions regarding spatial attention. All they knew was that the clarity of the image depended on their brain’s activity. Here, we can observe a parallel with the training of neural networks, which also lack a semantic understanding of the underlying relationships between variables, yet are still able to learn effectively.

Most participants successfully learned to control the asymmetry of their alpha rhythms. Moreover, these brain changes caused measurable shifts in spatial attention. For example, when participants increased alpha rhythms in the left hemisphere, visual activity in the right visual field decreased, and vice versa. This bias in attention persisted even after training was completed.

Additional tests using the classic neurological attention tests confirmed that neurofeedback led to sustained shifts in attentional distribution, even long after the experiment had ended.

Will It work in practice?

Importantly, scientists observed no eye movements indicating that participants were trying to control their alpha rhythms visually. Their gaze remained fixed at the screen’s center, suggesting that they learned to mentally control attention without physically shifting their eyes.

These results open the door to further research and potential applications of alpha-based neurofeedback for treating attention disorders, such as attention deficit hyperactivity disorder (ADHD), or assisting recovery following strokes that impair spatial attention. In summary, alpha rhythm-based neurofeedback is a promising method allowing people to consciously and voluntarily regulate their attention, potentially improving quality of life and cognitive function.

A moment of reflection.

Naturally, such research raises more questions than it answers for a thinking person. How exactly does synchronization occur? Is it a symmetrical process, or does one interlocutor take the lead? Is it dangerous to synchronize with someone unknown? It appears that even without knowing what’s going on in the other person’s mind, we come under their influence to some extent. Could it be beneficial to synchronize with intelligent and morally sound individuals? (Here, I think I know the answer.) What determines the success of synchronization — does it happen faster with familiar people? Do such processes influence our choice of friends and partners? (More on this topic in the next spring column.)

And — though I can hardly believe I’m writing this — could this be a mechanism of psychic vampirism?

I hope that, over time, we will come to understand all this. In the meantime, peace to all, and may your synchronizations be only constructive.

References:

[1] Pérez, A., Carreiras, M. & Duñabeitia, J.A. Brain-to-brain entrainment: EEG interbrain synchronization while speaking and listening. Sci Rep 7, 4190 (2017). https://doi.org/10.1038/s41598-017-04464-4Yasaman Bagherzadeh, Daniel Baldauf, Dimitrios Pantazis, Robert Desimone. Alpha Synchrony and the Neurofeedback Control of Spatial Attention. Neuron, Volume 105, Issue 3, February 5, 2020. DOI: 10.1016/j.neuron.2019.11.001.

[2] Wikström, V., Saarikivi, K., Falcon, M., Makkonen, T., Martikainen, S., Putkinen, V., Cowley, B. U., & Tervaniemi, M. (2022). Inter-brain synchronization occurs without physical co-presence during cooperative online gaming. Neuropsychologia, 174, 108316. https://doi.org/10.1016/j.neuropsychologia.2022.108316

[3] Yasaman Bagherzadeh, Daniel Baldauf, Dimitrios Pantazis, Robert Desimone. Alpha Synchrony and the Neurofeedback Control of Spatial Attention.Neuron, Volume 105, Issue 3, February 5, 2020. DOI:10.1016/j.neuron.2019.11.001.