A recent study finds that noninvasive brain stimulation, activated while asleep, improves memory performance the next day. Could we be close to enhancing cognition while we catch some shut-eye?
Deep brain stimulation has been a hot topic among neuroscientists over recent years.
However, deep brain stimulation involves inserting electrodes deep into the brain, and of course, this is not something that is taken lightly — by neither patient nor doctor.
But noninvasive brain stimulation, as its name suggests, does not require direct access to the brain.
Recently, researchers have begun asking whether this more subtle procedure could improve aspects of cognition. In particular, scientists have wondered whether it might enhance human memory.
Sleep and memory
Sleep is now known to be vital for memory consolidation. Memories are thought to move from the hippocampus, a brain area responsible for laying down memories, to the neocortex, where they are stored as long-term memories.
Recently, scientists from the University of New Mexico in Albuquerque set out to investigate whether they could enhance this natural memory consolidation process. They tried to do this by stimulating the brain during sleep using a relatively new technique called closed-loop transcranial alternating current stimulation.
Firstly, the researchers trained participants on a realistic visual discrimination task. In this task, they were required to avoid explosive devices, snipers, and other dangerous objects and people. To do this, they had to look out for subtle cues in a complex environment.
Overnight, the participants slept in the laboratory and were subjected to noninvasive stimulation. The stimulation was programmed to match the phase and frequency of slow-wave oscillations occurring in the sleeping brain.
Scientists believe that these oscillations are an important part of memory consolidation; the team effectively bolstered the oscillations with artificial current.
Their findings were published earlier this week in The Journal of Neuroscience.
The next day, the participants were tested on a similar but novel visual task. After nocturnal stimulation, they performed better at detecting targets than after nights where no stimulation occurred. The researchers believe that the noninvasive stimulation helped the participants turn recent experiences into more robust memories.
Why is this important?
Studies such as this mark the first forays into a new area of science. For now, the research raises more questions than it answers, but it also provides new techniques to build upon and extend.
Of course, being able to improve one's memory without making any effort is a worthy goal, but there are deeper and more pressing potential uses. Deficits in memory and thinking are, of course, part of many conditions. This includes neurodegenerative diseases, which are steadily growing in prevalence yet widely untreatable.
Research such as this could pave the way to machines that help minimize cognitive shortfalls while a patient slumbers. We are a long way from that goal, but this is a step in the right direction.