In this series of articles, we look at the effects of exercise on the brain, including how exercise helps you learn. In the previous post on this subject, we saw how moderate-intensity physical activity enhances thinking ability by temporarily increasing brain blood flow. This effect works in the short term, as long as we continue to maintain the right exercise-intensity level: Not intense enough and we don’t augment blood flow to the brain; too intense and blood flow returns to baseline flow levels all while the demands of exercise require us to increasingly focus on the exercise itself (not the problem you’re trying to solve in your head).
So, an interesting question to ask is this: can exercise induce lasting improvements in cognitive ability? Current research suggests that the answer to this question is yes. It promotes an increase in the levels of certain substances that enhance the brain’s capacity to acquire and retain new information.
For most of the twentieth century, scientists believed that we stopped producing new neurons soon after birth. Studies beginning in the 1980s, however, revealed that brain structure remains dynamic throughout life. One area of our central nervous system that has a remarkable capacity for new growth and reorganization of neuron connections is the hippocampus. This seahorse-shaped brain area plays a central role in learning and memory, among other functions, and it is now clear that parts of it continue to develop even in adulthood.
How Does the Brain Form Memories?
To acquire new knowledge, neurons must form new connections – known as synapses. Our memories, if you can believe it, are stored across these synapses. Allow me to explain further.
When you learn something, a pattern of neuron firing takes place that represents the new concept. When that particular brain activity pattern is fired with enough intensity and with adequate regularity, a memory is formed because the physical structure of the connections are changed. A stored memory means we can reproduce the information in our heads either as a thought or even a subconscious skill or reaction. To retain what’s been learned, these connections must be maintained, which usually only happens with repeated use. This is why it’s really hard to remember the name of the person who you knew perfectly well in high school but haven’t seen in 20 years. Use it or lose it. So, learning requires that the actual structure of neurons physically change and in order to do this, the right chemicals are needed. Thus, acquiring and maintaining memories demands the right supply of chemicals and stimulation.
How Exercise Helps You Learn: Novel Stimulation
This ability to change neuron connections is favored when we are placed in an environment with lots of stimulation, and one that is supportive of the act of learning itself. Animals living in environments that offer opportunities for a variety of stimulation – social, cognitive, sensory, and motor – show enhanced formation of new neurons compared to animals living in standard laboratory cages. In particular, exercise stands out as a powerful stimulus to enhance learning largely because it triggers the production of substances that stimulate neuron interconnectivity. How does this happen?
How Exercise Helps You Learn: BDNF
When we exercise, we activate forebrain neurons that use the neurotransmitters acetylcholine and gamma-aminobutyric acid (GABA). These signals tell the memory-forming hippocampus to produce a protein called brain-derived neurotrophic factor (BDNF), which then helps neurons grow and connect.
In response to exercise, an increase in BDNF is seen within days and results in a multi-fold surge in the production and survival of new neurons. The increase peaks after just 3 days of running and remains elevated for weeks when regular physical activity is sustained. So what happens if you use drugs that prevent BDNF from binding to its receptors? You prevent the beneficial effects of exercise on learning, which points towards the importance of this growth factor as a key mediator of the effect.
This is likely one of the reasons your cognition will benefit more with regular physical activity mixed into your weekly pattern of living versus an alternative of making only large, occasional efforts (e.g., several hour bike rides a few times a month). Yes, keep those weekly Exercise Scores in the exercise tracker above 100%!
How Exercise Helps You Learn: Effects on Neurotransmitter Systems
As mentioned above, physical activity stimulates the release of certain neurotransmitters, which then stimulate the production of BDNF. But this increase in neurotransmitter pools, itself, can directly enhance learning, memory, and thinking ability. For example, exercise at >80% maximal heart rate increases the synthesis of glutamate and GABA in the anterior cingulate cortex. Let me tell you why you want this. Strong activity in this brain region helps you starting working on a project by selecting specific tasks in favor of other things on your plate (choice selection), helps you maintain focused on a project (distraction filtering), helps you regulate emotions while you work, and helps you hold pieces of information in your mind as you try to solve problems (i.e., all processes of executive functioning and working memory).
Essentially, by increasing the pools of these neurotransmitters, regular exercise makes it easier for neurons to function optimally. Indeed, in response to regular exercise, neurons in the prefrontal cortex are not only more apt to interconnect, are stronger and more amenable to growth, but they are also more resistant to damage, particularly in older adults.
How Exercise Helps You Learn: Effects on Stress Resistance
Exercise may also aid memory indirectly by reducing chronic stress and increasing stress resistance. Prolonged exposure to heightened stress elevates glucocorticoid hormones. Elevated levels of stress hormones interfere with the ability to write new memories. Because exercise is a stress-relieving activity (as long as we don’t overdo it), glucocorticoid production is reduced. This helps us deal with stressful conditions better, limiting its physiological consequences, and preventing stressful situations from interfering with our ability to learn well and think clearly. Exercise doesn’t just make our muscles stronger, it makes our brain stronger too, and helps us maintain good mental performance in the face of real life.
It has been established that exercise has numerous unique physiological effects that are likely to make the brain more adept at restructuring itself to learn and retain new information. I find this idea particularly appealing – it’s like upgrading your brain to make the process of learning faster, easier, and more durable.
In the last article I wrote on physical activity and cognition, I discussed how exercise at an intensity of 60% max effort helps us think well now. Here, I discuss how higher intensity exercise promotes an environment that keeps neurons connecting and augments neurotransmitter systems that help us stay sharp. This is just one more reason we promote a mixed intensity (ie., low to high-intensity physical efforts) movement practice as a part of our Enduring Mover concept upon which much of our guidance and even our tracking tools are based.
In subsequent articles, we will be looking at other ways that exercise can help achieve this goal. And later, we will look at the practical evidence for its effects in human cognition.