(Dear reader: This is the first of a series on the neuroscience of these topics and their relevance to the practice of medicine and medical education. The references will be given at the end of the series. In addition, if you are near New York City, hope you can visit the special exhibit on the Brain at the Museum of Natural History. It runs through July of 2011. Thanks)
Consciousness, empathy and wisdom were in the domain of philosophers and religious scholars. Not any more. Neuroscience has started studying these functions of the human brain. The results of investigations by the neuroscientists are exciting and will have practical applications in understanding normal and abnormal mental functions. It will have an impact on the way we care for patients, particularly those of mental illness and Alzheimer. An understanding of empathy and wisdom may help us physicians in our own development and in medical education too.
Observations of patients undergoing brain surgery and patients with head injury and tumors had helped localization of functions to specific areas of the brain, even before the availability of recent research techniques. (Please read articles by Broca and Penfield and books by Oliver Sacks for details). Ancient Egyptian documents (Edwin Smith Papyrus) describe paralysis of the right half of the body in a person who fell off a chariot and had injury to the left side of the head. More recently the famous Mr.Phineas Gage had a remarkable recovery from a missile injury to the frontal cortex of the brain and lived to show changes in his personality and behavior suggesting that this area of the brain is necessary for our “executive functions”.
Now there are powerful tools such as fMRI and SPECT which can study the brain of normal persons in action when experiencing specific emotions and during specific mental activities. An even more powerful tool called optogenetics may open up study of the brain at a cellular level.
Observations of patients with specific mental deficits and functional imaging studies have shown that memory functions of the brain are mediated by several areas of the brain, each one specific for particular aspect of memory. Episodic memory (eg: remembering what you ate for lunch or dinner yesterday) depends on the medial temporal and prefrontal cortex. Semantic memory (word and speech based) depends on the integrity of the inferolaterl temporal lobe. Procedural memory (eg: driving) are mediated through cerebellum and motor cortex. Working memory for spatial details is carried out by prefrontal cortex and visual-association areas.
More recently, studies using functional imaging show that coordinated activity in specific areas of the brain (neural circuitry) determine specific mental functions, mood and behavior. For example, coordinated processing of information between amygdala, hypothalamus and hippocampus is involved in determining our moods. Fear circuitry involves amygdala and ventromedial prefrontal cortex and dopaminergic circuitry is involved in reward and expectation of reward functions. Abnormalities in the functioning of these circuits have been implicated in depression, Post Traumatic Stress Disorder and impulsivity.
Several years back, the so-called “mirror neurons” were described in the ventral premotor cortex of the brain. These neurons get activated when a subject is involved in a specific motor activity such as grasping an object. What is interesting is that this area will get activated in an observer also. Since then we know that this mirror activity is not confined to observing someone in activity. It is applicable to seeing someone else in pain. Activation of specific areas of the brain occurs both in someone who is experiencing physical pain and someone dear to the subject who is observing this experience.
It appears the that “the ability to project ourselves imaginatively into another person’s perspective by simulating their mental activity by using our own mental apparatus “ is involved in our ability to read each other’s mind. “To understand what another person is doing, we simulate his movements using our own motor programs; to understand what another person is feeling, we simulate his feelings using our own affective programs”.
For example when one experiences pain, several areas of the brain show increased activity. They include periaqueductal grey, thalamus, insula, anterior cingulate (areas 24, 25, 32 and 249,329) and prefrontal cortex (areas 9, 10, 44). When someone dear to you is getting stuck with a needle for a medical procedure and you are watching it, the same areas of the brain that light up in the other person will light up (become active) in you also. In other words, this is the neural correlate of empathy.
We can see how “mirroring” of neural representation is important in human relationships and in the survival of early societies. This is the neuro-biological basis of empathy, compassion, helpfulness and altruism. This leads me to a discussion of empathy in medicine.
0 comments:
Post a Comment