In a study of healthy volunteers, National Institutes of Health researchers have mapped out the brain activity that flows when we learn a new skill, such as playing a new song on the piano, and discovered why taking short breaks from practice is a key to learning. The researchers found that during rest the volunteers’ brains rapidly and repeatedly replayed faster versions of the activity seen while they practiced typing a code. The more a volunteer replayed the activity the better they performed during subsequent practice sessions, suggesting rest strengthened memories.
“Our results support the idea that wakeful rest plays just as important a role as practice in learning a new skill. It appears to be the period when our brains compress and consolidate memories of what we just practiced,” said Leonardo G. Cohen, M.D., senior investigator at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and the senior author of the study published in Cell Reports. “Understanding this role of neural replay may not only help shape how we learn new skills but also how we help patients recover skills lost after neurological injury like stroke.”
The study was conducted at the NIH Clinical Center. Dr. Cohen’s team used a highly sensitive scanning technique, called magnetoencephalography, to record the brain waves of 33 healthy, right-handed volunteers as they learned to type a five-digit test code with their left hands. The subjects sat in a chair and under the scanner’s long, cone-shaped cap. An experiment began when a subject was shown the code “41234” on a screen and asked to type it out as many times as possible for 10 seconds and then take a 10 second break. Subjects were asked to repeat this cycle of alternating practice and rest sessions a total of 35 times.
“Surprisingly we found that the satellite galaxies formed more or fewer stars depending on their orientation with respect to the central galaxy”, explains Annalisa Pillepich, researcher at the Max Planck Institute for Astronomy (MPIA, Germany) and co-author of the article. To try to explain this geometrical effect on the properties of the satellite galaxies the researchers used a cosmological simulation of the Universe called Illustris-TNG whose code contains a specific way of handling the interaction between central black holes and their host galaxies. “Just as with the observations, the Illustris-TNG simulation shows a clear modulation of the star formation rate in satellite galaxies depending on their position with respect to the central galaxy”, she adds.
This result is doubly important because it gives observational support for the idea that central black holes play an important role in regulating the evolution of galaxies, which is a basic feature of our current understanding of the Universe. Nevertheless, this hypothesis is continually questioned, given the difficulty of measuring the possible effect of the black holes in real galaxies, rather than considering only theoretical implications.
These results suggest, then, that there is a particular coupling between the black holes and their galaxies, by which they can expel matter to great distances from the galactic centres, and can even affect the evolution of other nearby galaxies. “So not only can we observe the effects of central black holes on the evolution of galaxies, but our analysis opens the way to understand the details of the interaction”, explains Ignacio Martín Navarro, who is the first author of the article.
“This work has been possible due to collaboration between two communities: the observers and the theorists which, in the field of extragalactic Astrophysics, are finding that cosmological simulations are a useful tool to understand how the Universe behaves”, he concludes.