The brain tissue, flexible and complex, performs its functions through a symphony of brain waves. While diverse activities are performed simultaneously, the method by which the brain prevents interference between different wave frequencies has been a persistent mystery.
However, a team of scientists from the United States discovered that the trajectory of moving brain waves is synchronized with the nature of the task at hand: cognitive learning processes follow one direction, while memory and information retrieval mechanisms follow the opposite path.
“These findings… help us better understand how the brain supports a wide range of behaviors that involve precisely coordinated interactions between brain regions,” explains Uma Mohan, a neurologist at the US National Institutes of Health.
The research involved 93 individuals admitted to hospitals across the United States, who already had electrodes temporarily implanted in the cerebral cortex as part of treatment for refractory epilepsy. This procedure provided scientists with the unique opportunity to access areas usually inaccessible for study.
“It’s a rare opportunity to be able to see what’s happening directly in the brain while participants are engaging in different cognitive behaviors,” Mohan said .
The cortex, the most superficial layer of the brain, plays a crucial role in consciousness and cognitive behaviors such as attention and reasoning.
Mohan and his team monitored brain waves at theta (2-8 Hz) and alpha (8-13 Hz) frequencies, observing their flow across the cortical surface as participants engaged in different activities. Some of these activities involved memorizing sequences of words or characters; others, in turn, focused on retrieving this memorized information.
“We are looking at neural oscillations not as independent, stationary things, but as things that constantly and spontaneously move through the brain in a dynamic way,” notes Mohan.
It required considerable effort, combined with the use of advanced technologies, to decipher the complexity of brain signaling patterns between subjects and establish a discernible pattern. During the study, it was found that 67 of the participants exhibited brain waves of insufficient intensity for analysis during memorization activities.
The team suggests that the wide range of variations observed can be attributed to anatomical and physiological differences inherent to each individual, which possibly explains the lack of prior detection of these specific brain wave directions.
“We found that the waves tended to move from the back of the brain to the front while patients were committing something to memory,” explains Mohan.
The frontal lobe stands out as the brain region that is most activated during the process of constructing an internal context.
“When patients were later trying to remember the same information, these waves moved in the opposite direction, from the front to the back of the brain,” continues Mohan.
It remains a mystery whether neuronal signals are the conductors of brain activities or mere side effects thereof. However, there is a consensus that traveling brain waves play, at least, a fundamental role in coordinating the sequence and rhythm of functions in different areas of the brain.
Recent advances in research support this hypothesis.
The fluctuation of these waves reflects neuronal activity, providing insights into the flow of cellular communication through the brain in distinct pulses. Changes in the trajectory of brain waves can be crucial in reconfiguring this network of connections.
As knowledge deepens, innovative strategies will emerge to help individuals facing challenges such as memory loss.
“If a person’s waves are moving in the wrong direction when they are about to try to remember something, it can put them in a bad memory state,” Mohan said . “If you could apply the stimulation in the right way, perhaps you could make these waves move in a different direction, triggering a fundamentally different memory state.”
Although many of us use our brains without fully understanding how it works, there is a vast amount of knowledge to be gained for times when we face difficulties. The good news is that neuroscientists are getting closer to deciphering the complex ‘dance steps’ of our mind.
This research was published in Nature Human Behavior.
