It was long thought that new neurons could not be generated in the brain. This was understood as a static and invariable entity that simply degenerated as we aged or due to brain damage.
However, from the experiments of the biologist of the University of Berkeley (USA) Marian Diamond, it was shown in 1964 that the adult brain was plastic and adaptive. This study was pioneering in identifying how environmental characteristics directly affected brain development and growth.
Elena Zhukova / University of California at Berkeley
The experiment involved a large and spacious cage with twelve rats growing in an enriched environment (items to play or run on the spinning wheel, company, various food), as well as 12 other rats that were in a small cage. , isolated, without social or play stimuli.
After eighty days, Diamond analyzed his brains and discovered that the cerebral cortex had changed in the enriched environment group. In these, the cerebral cortex was more extensive, due to the growth of the dendritic spines of the neurons, angiogenesis was observed – greater number of blood vessels -, the level of the neurotransmitter acetylcholine was increased, as well as that of the brain-derived neutrophic factor, known by its acronym in English BDNF, a protein that is especially expressed in the cerebral cortex and hippocampus, key areas for processes such as learning and memory.
These data have generated countless studies aimed at analyzing the role of each of the elements that made up this enriched environment.
Marian Diamond / University of California at Berkeley
Neurogenesis and physical exercise
Since the pioneering studies of neuroplasticity, there has been many scientific evidences that show how factors such as diet, diverse cognitive activity, social environment, novelty and exercise are elements that unquestionably favor this phenomenon.
Focus on exercise.
The multiple benefits of regular exercise have been widely demonstrated in human and animal models. We know that it can contribute to neurogenesis, as well as play an important role in reversing and repairing existing neural damage in both mammals and fish.
Understanding how this process occurs, and what factors trigger it, can solve the puzzle to improve age-related memory loss and perhaps prevent neurodegenerative diseases, including Alzheimer’s.
The average brain contains about 100 billion brain cells, most of which were formed before birth. In the early stages of childhood, new brain cells continue to be generated at an accelerated rate. Over the years, neurogenesis gradually decreases, but the process does not stop even during old age. Neurotrophic factors help stimulate and control this process, with BDNF being the most important.
This is especially true in the dentate gyrus of the hippocampus, although there are other brain regions that also produce new brain cells.
brainmaps.org, CC BY
Recently, a Harvard University research team, led by Rudolph Tanzi, found that the hippocampus can produce between 700 and 1,500 new neurons each day. This may not seem like much if we consider the vast galaxy of neurons we possess, but even this small number has value, as it keeps many existing neural connections active.
So while most brains can develop new cells, the goal of science now is to find the best ways to do so. The idea would be that if the number of neurons can be further increased through neurogenesis, the main function of the hippocampus could be intensified and the way in which people learn new information and access short-term memory could be improved. long term .
The results of this study support the link between exercise and neurogenesis.
It was found that aerobic exercise for eight weeks can double the ratio of generation of new neurons in the hippocampus, relative to those subjects who do not exercise.
In addition to producing BDNF, aerobic exercise could help increase liver production of an enzyme (Gpld1), which can also help with neurogenesis. We know that exercise manages to accelerate the maturation of stem cells into fully functional adult cells and promotes the main existing cellular mechanism for learning and memory, called long-term learning. All of these elements are key to fostering learning and memory.
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Although these findings come from animal studies, people could get the same brain benefits through aerobic exercise. At this time, there is no substitute for regular exercise to help with neurogenesis.
However, it is not clear what type of aerobic exercise works best, or how long and how much is enough. There are data that suggest between 120 and 150 recommended minutes of moderate-intensity exercise per week.
Studies point to swimming as one of the most complete sports. It promotes a clear cognitive benefit (improvements in attentional processes, cognitive flexibility, memory) in both young and old people. However, any physical exercise that increases your heart rate, such as using a treadmill, cycling or walking hard, are ideal. The moving brain learns faster.
Isabel María Martín Montsó, Professor at the University of Seville. Dra in Psychology. Neuroscientist. Area of specialization: Psychobiology. Neural basis of learning, memory and emotion, University of Seville
This article was originally published in The Conversation. Read the original.