Sleep Helps The Brain Process Emotions, And a New Study in Mice Reveals How

A new study has shown that sleep helps the brain process emotions for the next day, and it could help us understand some of the mysteries of human sleep.

There is overwhelming evidence that REM sleep helps humans consolidate their emotional memories, but the role of sleep in brain function is still a mystery.

Scientists are still trying to figure out how that plays out in the brain.

The prefrontal cortex is a part of the brain that is heavily involved in emotional processing, and yet during REM sleep some of its neurons, known as pyramidal neurons, are strangely quiet.

At first, that might sound odd. How is this part of the brain helping us control our emotions during sleep if it is not being active?

Silence is a powerful tool. The quieting of the prefrontal cortex during REM sleep helps the whole system reset according to research.

The findings are consistent with other recent studies that suggest sleep keeps activity under control.

Without proper REM sleep, networks in the brain can become overwhelmed with emotional messages, making it harder to determine important signals from background noise. This can cause a mouse to act fearfully when awake.

The dendrites in the brain send messages when they are active and awake. The body of the soma is where the messages are sent.

The dendrites show increased activity, but the soma shows decreased activity during REM sleep.

"This means a separation of the two cellular compartments, in other words soma wide asleep and dendrites wide awake", explains neurologist Antoine Adamantidis from the University of Bern in Switzerland.

In simple terms, this means that the neurons are not sending messages.

With the body of the neuron no longer sending off as many messages, the arms of the neuron have time to consolidate the information they have already received, which incoming messages should be sent off and which should not.

Animals can discriminate between danger and safety with greater effect if the brain is able to respond to environmental changes the next day.

The mice in the study lost their ability to discriminate between danger and safety when the activity of dendrites was reduced.

When the soma was not silenced during REM sleep, mice became more aware of danger signals.

The authors suggest that this may result in overconsolidation of emotional memories observed in post-traumatic stress disorders.

The mechanism has not yet been observed in humans, but it could help scientists understand why conditions like post traumatic stress disorder and sleep disorders are so closely linked.

Science published the study.