The Effects of Exercise on the Brain
September 24, 2014
It is relatively well known that exercise is good for the heart. It is also well accepted that exercise can reduce the incidence of diseases associated with obesity such as adult onset diabetes. But did you know exercise is linked to better cognitive function?
The brain operates through the transmission of information from one portion to another. It is a complex web: some areas communicating with many others at times, and a few areas at other times. There are major pathways that are used frequently, and others that are used infrequently. There are competing signals, some coaxing a message forward (facilitory) and others reducing the potential for the message to move forward (inhibitory). Eighty percent of this competition happens between two major neurotransmitters, glutamate, which facilitates a transmission, and GABA (gamma-aminobutyric acid), which inhibits a transmission.
This video illustrates the concept pretty well:
You also have your regulators that mostly over-ride or adjust the flow of information, but are also capable of delivering a signal directly. These include serotonin (polices brain activity such as mood, impulsivity and aggression), norepinephrine (enhances transmissions for attention, arousal, and perception), and dopamine (which enhances transmissions for learning, attention and movement). Exercise balances these neurotransmitters.
Here’s the physiology of learning: there is an initial stimulant to learn. Glutamate crosses the nerve synapse. This signals the nearby receptor. The receptor nerve produces regulators which enhances the firing which occurs across the synapse. This makes the transmission occur more easily, with less stimuli. Genes in the nucleus of the nerve turn on. You now have a new memory.
In exercised mice, the more they ran, the higher the level of BDNF. This largely occurred in the hippocampus. Researchers in Germany found that people who exercised prior to learning vocabulary words did so 20% faster than those trying to learn them before exercise. At Naperville Central High School in IL, PE teachers developed a program called “zero hour.” The students exercised at 80-90% of their aerobic capacity for 1 hour before class. They found a 17% improvement in literacy scores vs. only 10.7% improvement among students who only did regular PE. The student population scored 1st in science and 6th in math (in the world!). The CA Department of Education found that fit students scored higher academically than unfit students (twice as well!). EEG tests indicate more neural connections and activity during a task in those that are fit than those who are not. Exercise is linked to higher BDNF levels.
Specific proteins are also needed to optimize learning a new task or idea. BDNF (brain derived neurotropic factor), a protein stored in the hippocampus, is like Miracle Grow for your brain. It is present in higher levels in those who exercise. BDNF binds to receptors at the synapse to increase/enhance ionic flow to increase signal strength at the synapse. It stays near the synapse once the blood starts pumping with exercise. Hormones (IGF-1, VEGF, FGF-2) pass through the blood brain barrier during exercise to help enhance BDNF function, sort of like “oiling the wheel of learning.” The hormones activate genes that produce more BDNF, serotonin, and other proteins needed for synapse building. Besides enhancing neuron function, BDNF helps with neuronal growth. BDNF also has a role in protecting neurons from cell death. This allows more information to be received, associated, remembered, and put into context.
Complex exercise occurs through interconnections between the cerebellum and prefrontal cortex, which is directly involved in learning a new task. The prefrontal cortex organizes physical and mental activity. It gathers information and compares it to existing memory. It then delegates learned tasks to the cerebellum, basal ganglia and brain stem. This frees it from previously learned tasks, so it is available to learn new ones. The brain pathways and transmitters used in academic endeavors are optimized in the presence of regular exercise.
Complicated enough? Let’s make it simple. The sea squirt enters the world with a simple spinal cord, and a 300-neuron brain. It has 12 hours to anchor itself to a landing site, or it dies. Once it finds a good place to perch, it doesn’t need its nervous system to move, so it EATS ITS OWN BRAIN. Avoid the fate of the sea squirt. Get off the couch and MOVE!
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