Metronomous neurons: a new type of nerve cell?

New scientific research has discovered a type of neuron that acts like a kind of clock or metronome, keeping the brain in sync.

These brain cells, called metronomous neurons, Could play a key role in the coordination of neuronal activity.

    Gamma waves: the conductors?

    Our brain is like a large concert hall. In order to direct and manage many complex cognitive processes, it is necessary that different groups of neurons are activated and, like the different members of a musical orchestra, work in harmony to produce a symphony of processes that allow us to perceive and to interact. with our environment.

    But just like with orchestras, the brain may need a conductor to keep all of its parts active and in sync. In this regard, several neuroscientists claim that gamma rhythms, brain waves that fluctuate at a frequency of about 40 cycles per second, could perform this function.

    One thinks that these oscillations of gamma waves would act as a kind of clock or metronome which coordinates the transfer of information from one group of neurons to another, so there seems to be a lot of evidence to suggest that the role of gamma waves in cognitive processing is critical.

    Over decades of research in humans and other animals, patterns have been found in many areas of the brain that have been associated with a variety of cognitive processes, such as attention or working memory. Some studies have even linked alterations in these gamma oscillations to various neurological diseases, including Alzheimer’s disease and schizophrenia.

    However, there does not appear to be absolute consensus. Some neuroscientists believe that the role gamma waves play may not be so decisive and argue that these rhythms may be correlated with brain activity, but would not make a significant contribution to it.

    Metronomous neurons: studies in mice

    To determine if gamma waves really played an important role in the coordination of neuronal activity, Brown University neuroscientists Moore and Shin begin their study in mice, Discover that an unknown set of neurons would act like a metronome.

    These newly discovered cells fired rhythmically at gamma frequencies (30 to 55 cycles per second), regardless of what was happening in the external environment, and the likelihood of an animal detecting a sensory stimulus was associated with their ability of neurons to to manage time.

    Moore and Shin began their research as a general survey of brain activity related to the perception of touch. And to do this, they implanted electrodes in a specific area of ​​the somatosensory cortex of the mouse, responsible for processing the inputs of the senses. They then measured neural activity by observing the rodents’ ability to notice subtle tapping on their whiskers.

    The researchers focused on gamma oscillations and decide to analyze a specific group of brain cells, called rapidly accelerating interneurons, Because previous studies had suggested that they might be involved in the generation of these rapid rhythms. The analysis revealed that, as expected, the degree to which these cells fired at gamma frequencies predicted how well the mice would be able to detect contact with their whiskers.

    But when neuroscientists delved into the study, they found something strange. And they hoped that cells that would be activated in response to a sensory stimulus would show the strongest links to perceptual precision. However, upon examining the cells, this link had weakened. Then they realized that cells may not be sensory and act like timers, regardless of what is going on in the environment.

    By repeating the analysis only with cells that did not respond to a sensory stimulus, the link with perceptual accuracy became stronger. In addition to not being disturbed by the external environment, this specific subset of neurons tended to increase steadily at gamma intervals, like a metronome. Furthermore, the more rhythmic the cells, the better the quality of the animals when it comes to detecting whiskers. What seemed to be happening, according to the original concert hall metaphor, is that the better the conductor manages time, the better the orchestra will do.

      Brain clocks

      We have all heard of the internal clock or the biological clock. And this is it our brain responds to the passage of time through physiological systems that allow us to live in harmony with the rhythms of nature, such as the cycles of day and night, or that of the seasons.

      The human brain uses two “clocks”. The first, our internal clock, which allows us to detect the passage of time and which is essential for us to develop on a daily basis. With this clock, we can, for example, measure the time elapsed between two activities, find out how much time we have spent performing a task such as driving or studying, otherwise such tasks would be prolonged indefinitely without any notion of the time that elapses. has elapsed. .

      The second watch could not only run in parallel with the first, but also compete with it. This brain system would be housed inside the first clock, and would work in conjunction with the cerebral cortex to integrate temporal information. This mechanism would be performed, for example, at times when our body is paying attention to how time has passed.

      As necessary, the feeling of being aware of the time that has passed is to keep a memory of what we have done during the process. And this is where a brain structure such as the hippocampus comes in, responsible for processes such as inhibition, long-term memory or space, as well as playing a key role in the memory of the passage of time, according to the latest scientific advances. studies.

      In the future, it will be essential to continue to develop new treatments and to study the relationship of these brain structures and our internal clocks with neurodegenerative diseases such as Alzheimer’s disease and other types of dementia, as well. as mental disorders and brain diseases involving degenerative processes. concept of time and body space.

      Bibliographical references:

      • Brown University (2019). Neuroscientists are discovering a type of neuron that acts as a metronome for the brain. Science Daily. Available at: https://www.sciencedaily.com/releases/2019/07/190718112415.htm.

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