This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
Does the brain influence behavior? This class is titled Neurobiology and Behavior. Another textbook for my Behavioral Neuroscience class was titled Physiology of Behavior and another book I have is titled Biological Psychology. One can observe that in both of these titles, the biology related term is first, followed by the word behavior. It is not surprising that many think that the first term always causes the other, and not the opposite. Being a psychology major, I tend to think that behavior comes first in a lot of examples. I would like to think that in many cases behavior causes biology. In class many examples describe how neurons interact with one another to produce behaviors. It is also important to observe how behaviors can change the biology of a person. This parallels the concepts learned in class that the input/output mechanism is bi-directional. Outputs (behaviors) can influence inputs (physiological mechanisms). Instead of observing behaviors like our leg muscles moving to cause changes in the firing of neurons, one example of an output influencing an input is the reaction to stress and how they affect our biological mechanisms.
Viewed from an evolutionary standpoint, in early times stress caused the stimulation of the sympathetic nervous system resulting in an outpouring of the hormones epinephrine, norepinephrine, and glucocorticoids that were essential to the life-preserving fight or flight reactions of primitive man (Anthony 1988). However, the nature of stress for the individual today is different. It is only occasionally and unexpectedly that one is confronted with overwhelming, life-threatening stresses. Present stresses arise from everyday stresses of work, finances and school. The problem is that the body still continues to respond in the same fashion as primitive times. This makes the large release of hormones very harmful. They can cause an increase in blood pressure, damage muscle tissue, lead to infertility, inhibit growth, damage the hippocampus and suppress the immune system (Carlson 1994). It is therefore, important that individuals learn to control the stresses in their lives. The more detrimental coping behaviors will cause a larger change in physiological effects. This shows that the behaviors chosen will affect our biological mechanisms. The harm from most forms of stress comes from our own response to it or experiences that shape the way we cope with it.
Individual differences in personality characteristics can alter the effects of stressful situations. The most important of these characteristics is the type of coping response that a person displays. There are two types of individuals that react to stress. Those who are stress-resistant and those who are stress-sensitive. When exposed to the same major threat, the stress-resistant responds to the challenge in a controlled way without being overwhelmed by it (Anthony 1988). These different types of strategies come under the spectrum of what is termed as emotional intelligence or EQ (Goleman 1995). There are those who are smart and learn to cope effectively and those who cant cope or who dont try at all.
What could cause people to have these personality types of stress sensitive and stress resistant? Many might say that this is where the biology comes in and that we are born with certain genes that tell us to cope in some way. Could this EQ be something that is biologically inherited. Biology does play some part, but experiences can also affect individuals nature of coping with stresses in a biological way. In a recent study, biologists have found that baby rats whose mothers lick them have physically different brain structures from those whose mothers dont (Begley 1998). The differences lie in the brain regions that respond to stress. Licked rats handle stress better then deprived rats do, suggesting that the experiences in life shapes the brain even with simple traits such as temperament. It is very important to understand that our brain has a plasticity that allows it to be shaped by our behaviors and experiences.
This short paper doesnt allow one to give an in-depth look into other studies of how behavior influences the brain. I hope that I have convinced others of the importance of behavioral mechanisms as opposed to considering just the brain mechanisms and the outputs they produce. It should be noted that we shouldnt ignore brain mechanisms, but we shouldnt place all the weight on them. When only brain mechanisms are used to explain the Unabombers obsessive-compulsive behavior, treating anorexics with prozac and explain schizophrenias cause due to genetics, it seems as if in the future there will be a biological basis for everything. Years ago, when the brain couldnt be observed in much detail, researchers thought that certain behaviors and experiences affected the individual in certain ways. It is important to understand that this decade of the brain allows us to see these actual changes that can occur to our brain structures and mechanisms due to certain behaviors and experiences. It is as if one were to scratch a record by mistake, listen to its output, realize something was wrong and then upon examining it find a visible scratch. Researchers now are looking for these scratches in the brain. But it is important to remember that we are responsible for what behaviors we do not just our brains. After all we did put the scratch on the record in the first place.
Anthony, E.James. "The Response to Overwhelming Stress in Children." In E. James Anthony and Colette Chiland, (Eds.), The Child In His Family, Vol 8. New York: John Wiley and Sons, 1988.
Begley, Sharon. "Is Everybody Crazy?" Newsweek. January 26, 1998, 50-56.
Carlson, Neil R. Physiology of Behavior. Boston: Allyn and Bacon, 1994.
Goleman, Daniel. Emotional Intelligence. New York: Bantam Books, 1995.
This student argued that behavior can shape brain biochemistry. This student's words were, "I would like to think that in many cases, behavior causes biology" (p.1). Since input/output is bi-directional, this must be true.
I, too, am interested in this question but from a religious perspective. Nevertheless, the "mechanics" of behavior producing biology would be the same. Do you know of any research in this "backward" approach to neurobiology? As far as you know, did this student pursue this idea any further? Any information will be appreciated.
By saying this, I don't mean at all to dismiss the sense of your question, but only to suggest that it needs some rephrasing. The issue, for me at least, isn't whether "behavior" affects "biology" but rather whether "biology" is a fixed thing which can't be affected by anything or a plastic thing which is constantly being reshaped both by what happens to it and by its own activity. And the answer in general is the latter. In the specific case at hand, the nervous system is clearly an entity which both causes "actions" and is altered by actions, both its own and those of others (cf http://serendip.brynmawr.edu/bb/brainpsychoanal.html).
What kinds of evidence say the nervous system is continually being altered rather than being fixed (ie "biology" is affected by "behavior")? Lots of different kinds, with more being described all the time. At a very simple level, a stressful event raises levels of circulating adrenalin which in turn changes the responsiveness of the nervous system to subsequent inputs. Prolonged stress, or particularly intense (traumatic) events produce observable long term changes in the nervous system (cf http://serendip.brynmawr.edu/bb/neuro/neuro02/web3/gimperato.html). Changes in the nervous system are also observable as consequences of various kinds of learning experiences (cf http://serendip.brynmawr.edu/sci_edu/education/brain.html). And as neurobiologists turn to the matter, it is becoming increasingly clear that changes in the nervous system result from social interactions as well (cf. http://serendip.brynmawr.edu/bb/neuro/neuro99/web1/Zaldivar.html).
Hope that gives you something to work with? And I'm curious about why this is a relevant issue "from a religious perspective"? We're in the process of developing a new Serendip section around issues of science and spirit, and your thoughts would be appreciated in this connection.
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