Throughout the day, the people retain a large amount of information. The brain creates or modifies the neural connections from that data, developing memories. But most of the information we receive is irrelevant and it makes no sense to keep. In such a case, the brain is burdening.
Until now there have been two hypotheses on how the sleeping brain alters the neural connections that are created throughout the day: while one argues that all of them are reinforced during sleep hours, the other holds that their number is reduced. To plumb what is the correct, a group of scientists from the laboratory of Ole Paulsen, University of Cambridge (Uk), has analyzed the mechanisms that underlie the maintenance of the memory during the phase of slow-wave sleep, in which there is a deep rest.
“Depending on the experiences of a person and in function of their relevance, the size of their corresponding neural connections changes. Are higher that are important information and the less that stored in the dispensable”, explains to Sinc Ana González Rueda, lead author of the study and researcher at the MRC Laboratory of Molecular Biology (LMB) in Cambridge. According to the expert, in the case that all these links are mutually equal during sleep, the brain is saturaría by an overdrive extreme of the nervous system.
In the study, published in the journal Neuron, the researchers stimulated the neuronal connections in mice subjected to a type of anesthesia that you get a brain state similar to the phase of slow-wave sleep in humans. In the words of González Wheel, the stimulation was performed “blind” because they do not know the information contained in each of the links. “We developed a system to track the evolution of a particular neuronal synapse and study what type of activity influences which these are kept, grow, or diminish”.
What depends on the maintenance of neuronal connections?
The results show that during slow-wave sleep, the connections larger are maintained while the children are lost. This brain mechanism improves the signal-to-noise –remains the important information and discarding the expendable– and it allows the storage of various types of information from one day to another without losing the previous data. That is to say, those who already have been considered relevant previously held in that state without having to re-reinforce them. “Although the brain has a storage capacity extraordinary, maintaining neuronal connections requires a lot of energy,” explains González Wheel.
According to González Wheel, the brain “place order” during the hours of sleep, discarding the connections more weak to ensure memories stronger and consolidated. “Although the brain has a storage capacity extraordinary, to maintain connections and neural activities require a lot of energy. It is much more efficient to keep only what is necessary,” says the expert. “Even without keeping all the information that we received, the brain spends 20% of the calories we consume.”
This research is a first indication of the electrophysiological mechanism of the dream and opens up new horizons thanks to the development of a new way of studying synaptic plasticity in vivo.
The next target of the experts is to investigate the consequences of this type of brain activity for the maintenance of a particular information and analyze new phases of sleep. “In addition to the analysis of the phase of slow waves, might be interesting to know what happens in the phase of REM, during the cause of dreams,” concludes González Wheel.