If we knew until now that certain areas of our brain remain active when we sleep, a team of neuroscience researchers recently discovered that the phenomenon also exists in reverse: certain areas of the brain fall asleep when we are awake.
When we are in a state of deep sleep, brain activity increases and declines in waves depending on the moment and the areas of the brain, an activity that is essential in particular for our memory. A team of six neuroscientists from the universities of Stanford, USA, and Newcastle, UK have discovered the existence of the same cycles when the brain is awake with small areas falling asleep and waking up independently.
In this study, the researchers show in particular that the neurons which are in a more active, more alert state are those which respond best to environmental stimuli and that these remain longer in this state of activity when we are focused on a particular task. Findings that suggest processes that regulate brain activity during sleep may also play a role in attention when the brain is awake.
These new discoveries on the activity cycles of the brain teach us a little more about the way in which it is organized. If previous studies had already shown the ability of neurons to switch from an active mode to a sleeping mode, it was always individually. Here, we observe for the first time such fluctuations on all the neurons of a given group which coordinate on small cycles.
These fluctuations and relays passed between groups of neurons play a role in saving energy for the human body. Indeed, it might seem logical that if these groups went into active mode at the same time, we would be more efficient, more alert and responsive to the environment. For Kwabena Boahen, in charge of the study, this is impossible for metabolic reasons. » If the neurons were in a constant state of discharge, it would be very costly in terms of energy. « . This fluctuating activity therefore makes it possible to save energy, but also to clean up the waste harmful to the cells generated during periods of activity.
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