Electrical activity in the brain
For years, researchers have registered electrical activity in the brain; activity that fluctuates or alternates during sleep. It can be measured on an ‘EEG’, where it shows as waves. These waves are referred to as ‘sleep spindles’, and researchers have suspected this brain activity to be involved in the recording and storage of memories, while we sleep.
The researchers were unaware of how this brain activity functioned during sleep – maybe it enabled or even caused the storage and consolidation of memories to happen. According to one of the researchers from the study, the activity might have been a byproduct of other brain processes involved with storage of the memory. However, the study showed that the activity is central to the process of creating memories, which is necessary in our everyday lives. Further, the results showed that it is possible to target these spindles to improve the ability to memorize.
This is a new standpoint for science, as it marks the first time that a group of researchers have been able to target the brain activity at these sleep spindles, without also increasing other natural electric brain spindles during sleep. This has never been achieved with ‘Transcranial direct-current stimulation’ (TDC), which is a constant stream of weak electric current applied to the scalp.
In this new study, 16 research participants had to sleep simultaneously with having their electric brain activity measured during the study. This was done using electric electrodes that were glued to their scalp. Before they were asked to go to sleep, the participants had to conduct two common exercises for the memory, which involved a word parring test and movement strokes. During one of the two nights, the participants were given Transcranial alternating-current, which was synchronised with the brain's natural sleep spindles. The second night, they received a false stimulation as a placebo, while they were sleeping.
Every morning, the participants had to do the same memory exercises. Researchers did not observe any improvement in the word parring test after either of the two nights, but the participants improved their skills in the movement strokes after the night with Transcranial alternating-current.
Based on these results, the researcher behind the study believes that there is a direct link between electric activity and motoric memory. This discovery is very interesting to researchers as they already know that sleep spindles, as well as the formation of memories, are disrupted in patients suffering from various diseases, herein Schizophrenia and Alzheimer’s.
Hope for new treatment in the future
Therefore, the researchers hope that this experience can help them target the treatment for these sleep spindles to improve the formation of memory and the cognitive skills in patients suffering from a long list of diseases, where these abilities are disrupted.
Next step for the researchers will be to try to provide this non-invasive stimulation to people with a disease that is known to lack this sleep activity. It is anticipated that this will improve their memory - as was shown with the healthy participants. Maybe one day, it will be possible to use tiny electrodes before going to sleep, and then wake up the morning after with improved memory, without having felt a thing during the night.
