Not all areas of the brain are asleep or awake at the same time, according to new research in mice.
- By examining the brain activity of mice, researchers were able to study more precisely the distinctions in the brain between sleep and wakefulness – in other words, the processes that govern consciousness.
- They have discovered, for the first time, that small regions of the brain can remain momentarily awake while the rest of the organ remains asleep – and vice versa.
- These “flickers” are particularly surprising, according to the scientists, because “they do not follow the rules dictating the brain’s strict cycle from waking to slow-wave sleep to REM sleep.”
“Sleep and wakefulness are completely separate states that define the boundaries of our daily lives. For years, scientists have measured the difference between these instinctive neurological processes by observing brain waves, with sleep being characterized by slow, long waves measured in tenths of a second that travel throughout the brain.”
Using a new method to study the brain waves that govern consciousness, a team of researchers has discovered for the first time that small regions of the brain can momentarily remain awake while the rest of the organ remains asleep – and vice versa.
Neural activity patterns to predict whether the brain is asleep or awake
As part of their work, published in the journal Nature Neurosciencescientists from several American universities studied the brains of mice for four years using a headset that recorded the electrical signals of their brain activity in ten specific regions. Using these massive amounts of brainwave data, they were able to artificially create new patterns of neural activity that were only a few milliseconds long. This allowed them to study more precisely the distinctions in the brain between sleep and wakefulness, in other words the processes that govern consciousness.
Knowing that sleep is traditionally defined by slow waves, the researchers asked the neural network to predict whether the brain was asleep or awake. The model was able to tell the difference between the two states of consciousness from just a few milliseconds of isolated brain activity data. “We observed the information with a level of detail never before seen, researchers congratulate themselves in a press release. It’s like being able to guess the rhythm of a song after hearing it for just a thousandth of a second.”
Some small regions of the brain sleep while the rest is awake
By studying these sleep/wake prediction models, scientists were also “surprised” to note that not all areas of the brain are asleep or awake at the same time. “For a fraction of a second, the model detected wakefulness in one brain region while the rest of the brain remained asleep. Or conversely, one region was asleep while others remained awake.”they explain. But what is the role of these “glitters”, these “flashes” on the functions of sleep and wakefulness?
By observing the behavior of the mice, they found that “When one region of the brain blinked to sleep while the rest of the brain was awake, the rodent would pause for a second, almost as if it were ‘switching off.'” Likewise, “the flashing of a region during sleep (i.e. its awakening) could be detected by the tremors of the animal during its sleep”These flickers are particularly astonishing, according to the authors, because “they don’t follow the rules that dictate the brain’s strict cycle from waking to slow-wave sleep to REM sleep.”
Understanding more about the high-frequency neural patterns and flickers between wakefulness and sleep could help researchers better understand neurodegenerative and psychiatric diseases, both of which are associated with sleep disturbances.
