Emotional States in Brain Injury
by Robert P. Lehr Jr., Ph.D.
People who suffer brain injuries frequently behave in ways that are quite different from what we might expect. They often say and do things that are not typical of the way they acted prior to the injury. In particular they may act in aggressive ways and say and do things that seem extreme. Many patients experience emotional outbursts, expressing thoughts that are less than acceptable in the social environment surrounding them. Why do they do this and where are the structures in the brain that might be responsible for these actions?
Hypothalamus
Scientists are gaining new insight into the structures deep within the brain that are the foundations of our emotions. We recognize emotional states in ourselves and others by their outward appearances. When people are angry we feel or see a flushed face, clenched fist, and perhaps an angry cry. These responses come from deep within our brains from a structure called the hypothalamus. It is an old structure that is the seat of our emotions and the highest center of integration for our autonomic nervous system, the system that controls our heart rate, breathing, and other automatic responses.
Amygdala
Another structure that has been identified as being involved in emotions is the amygdala (a Greek word meaning almond, which refers to its basic shape). This small collection of neurons is found in the anterior portion of the temporal lobe, just ahead of the hippocampus, a structure of importance in memory and learning. Recent research has shown that part of the amygdala is responsible for our ability to learn what is fearful to us. That these structures are deep within the brain indicates that they are very old and have served throughout evolution to protect the creature from its predators. The amygdala is closely connected to another structure deep within our brain, the thalamus. The thalamus is a central clearing house for all the incoming stimuli we receive from the environment. There are neuronal pathways that interconnect the amygdala and the thalamus. We thus have a neural mechanism that links incoming senses and our knowledge about them at a very primitive level. This is a level of which we are not consciously aware. We become angry very quickly and then later become aware of why we are so angry.
Frontal Lobes
Lastly, there are the frontal lobes of the brain, which help us control our emotions and conform to our social surroundings. The frontal lobes are responsible for planning our responses to situations, initiating actions, and setting the standards for our social interactions. We now believe that this control is obtained by the inhibiting structures deep within the brain. This inhibition controls the outward expression of our emotions. If injuries are sustained to the frontal lobes of the brain, then we have, in effect, removed the inhibition and free expression of emotions is more likely. It should be pointed out that this outward expression is not always desirable, and that the individual who exhibits this behavior may not be aware of its inappropriateness.
Our awareness of the neural structures for emotion, and an understanding of how those structures bring about emotional response, allows us to better understand someone who has been brain injured. The fact that emotions are very old responses and are learned forms of behavior helps us to provide better forms of therapy for the individual. Regaining control over emotional expression is a matter of relearning the inhibition of these deep structures through the association of the thalamic and amygdaloid interconnections. For example, remaining calm while the individual is acting out provides modeling of emotional control and decreases the chance of inadvertently reinforcing lack of inhibition. Remember that rehabilitation is repetition, repetition, repetition, until the new behavior is learned. Then the behavior is reinforced to establish a new relationship with the environment. In this case, it is the expression of emotion that is rehabilitated.
The author, Robert P. Lehr Jr., Ph. D. is Professor Emeritus of the Southern Illinois University School of Medicine in Carbondale, Illinois. He now operates Lehr Information Services (508-896-4076) on Cape Cod, Massachussetts, which offers services in technical writing, editing and research.
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