The brain functions associated with learning occur when neurons communicate with each other by the release and uptake of neurotransmitters. Many chemicals are known to function as neurotransmitters, and also many chemicals are known to influence the functioning of neurotransmitters. Further, cognitive scientists have identified several environmental factors that are associated with the production and function of neurotransmitters and the growth of neurons or the tissue needed to support neurons. All of these factors influence how the brain perceives the world, cognates, and responds to the world; so they affect how humans interact socially and thus learn.
Several examples of neurotransmitters illustrate the effects that these chemicals can have on brain function. Glutamate is a neurotransmitter that crosses the synapses when two neurons first communicate, so it is present when a pathway is first wired. Serotonin is associated with moods and emotions; abnormal levels of this neurotransmitter are associated with depression, anxiety, and similar conditions that can be debilitating. Drugs to control the level of serotonin have reduced the symptoms of these conditions in many individuals. Norepinephrine is associated with levels of attention and motivation; too much or too little of this neurotransmitter can interfere with one’s ability to pay attention to important parts of the environment. Dopamine is a neurotransmitter associated with one’s perception of reward and with learning. Many addictions can be explained by the release of dopamine when the addict engages in the addictive behavior.
In addition to the role of many neurotransmitters that influence brain function, cognitive scientists have elucidated the role of structures in the brain that function in the control of humans’ social interactions. The amgydala is associated with emotional responses to situations. Emotional responses can be either negative (for example when many of us are frightened by a snake) or positive (the emotional attachment that we feel when seeing family members). The hippocampus is associated with sorting and storing information, so it must function normally for cognition and memory to occur.
It is becoming a well-established observation that information enters the brain and the amygdala “decides” if that information is important. Meaningful information is passed it along to the hippocampus which “decides” how to sort and store the information. In reality, all of the processes are far more complex, but even when oversimplified, educators have a more accurate and sophisticated understanding of human learning if they perceive that emotion and the environment affects brains. Several discoveries about the environment and brain function have particular relevance to educators designing exemplary practices for 21st century curriculum and instruction.
First, moderate levels of exercise are good for brain function. Moderate is a difficult quantity to define, and the data are not yet conclusive, but it appears that the physician who recommends aerobic exercise that raises your heart rate to 80% of maximum for 20 minutes three times per week is recommending too little exercise. Fit bodies deliver food, water, and oxygen to brain cells and those are all necessary for proper function. In experiments, humans who exercise at moderate levels had higher levels of brain-derived neurotrophic factor (BDNF) than those who did not exercise. BDNF is a protein that is used to build neurons and the other tissues in the brain, as well as to maintain healthy function in synapses. Further, exercise is associated with the production of chemicals that are associated with neurotransmitter uptake as well as the factors associated with the building and repair of capillaries (the tiny blood vessels that carry blood to cells including neurons). From this we can conclude that educational structures and organizations restricting students’ opportunities to move around can interfere with healthy brain function. These findings support the inclusion of fitness-based physical education programs in the curriculum and these findings refute policies restricting participation in extracurricular athletics for academic reasons. Further, these findings suggest that decisions to reduce physical education classes to allow for enhanced academic instruction as a strategy for improving test performance is likely to result in the opposite effect.
Second, enriched environments are good for brains. This conclusion comes from research in which rodents were kept in two different environments; those kept alone and in cages without structures on which to climb or other toys had brains with fewer connections than were found in the brains of the mice kept together with other rodents in cages that contained complex toys and structures. This research has been criticized as it was not clear the changes in the brains were the result of brains atrophying in stark conditions, brains in stark conditions failing to develop properly, or brains growing abnormally complex in the enriched environments. The implications for educators are identical regardless of the causes of the changes: enriched environments are associated with richer connections in brains.
Third, stress can be either good for brains or bad for brains, depending on the level of stress that is experienced. What is true for physical stress (exercise) is true of psychological stress: none is bad, some is good, but too much is bad. Stress results in the release of a chemical called cortisol into the blood. Although not a neurotransmitter itself, cortisol does influence the release of the neurotransmitter norephnepherine which affects both the brain and other organs. The fight-or-flight response with its characteristic increase heart rate and more focused attention is an example of the effects of norephnepherine. In moderate levels, cortisol is associated with normal and healthy building of new connections between neurons and the brain functions necessary for social interaction. Too much cortisol can interfere with the normal building of connections and brain function. Exposure to excessive levels of cortisol for an extended time (for example when individuals experience chronic stress) is associated with degraded brain function.
We can conclude that modern cognitive science is creating a model of the human brain that is more accurate and more detailed than ever available to educators. This situation is not unlike the changes in medicine that followed the discovery and elucidation of germ theory. Once scientists discovered germs and their role in disease, doctors began to take steps to minimize the spread of germs; for example, they started washing their hands frequently. It is anticipated that educators who ignore the effects of their classrooms on brains will be viewed with as much suspicion as doctors who ignore the advice to wash regularly