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Thursday, September 23, 2010

9.8 Cerebral Cortex 4: The Pre-Frontal Cortex, Seat of Our Minds

Physician's Notebooks 9 -  See Homepage - http://physiciansnotebook.blogspot.com

8. Brain, Mind? - Update 14 April 2018. The following descending headings list is in order of appearance in the text. Use search & find or scroll down to find.


Cognitive Control
Attention
The Pre-Frontal cortex and Behavior
Mind - What is It?

Cognitive ControlHow do you think? How do you decide what to pay attention to?

Attention: This focusing of the sensory apparatus is an essential feature of all sensory processing, as the great leader in behavioral psychology, William James, first noted in his Principles of Psychology (1890): Everyone knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects of trains of thought. Focalization, concentration of consciousness, are of its essence. It implies withdrawal from some things in order to deal effectively with others.

How do you manage to pursue long-term goals in the face of distractions, obstructions and frustrations that can knock you off task? In brief, how does your brain manage to orchestrate its billions of neurons and its trillions of synapses and nerve fibers to produce behavior that is willful, coordinated and extends over a lifetime? It does it by cognitive control, the ability of your thoughts and actions to rise above mere reactions, the ability to anticipate possible futures and coordinate and direct your thought and put it into action.
   Neuroscience is just now producing data that at least partially is answering these questions and, more importantly, is producing practical applications of the new knowledge that you may use to better your life. And its most important focus has come to be on the forward part of the cerebral cortex in the frontal lobe known as the Prefrontal Cortex, or PFC.

The Prefrontal cortex and BehaviorBehavior may be automatic (like breathing in and out) or willful. If you are about to be hit by a car, you leap out of the way before you even form an intention in your mind to do so. Such responses seem to depend on genetic programs in the brain, developed over millions of years to promote survival in reaction to sudden fear. They are driven in a "bottom-up" fashion: the sensory stimulus at the bottom (the perception of the car bearing down to hit you) triggers an automatic motor response up in the central nervous system, not necessarily as high as the brain. 
   Opposite to this reflex action, the pre-frontal cerebral cortex neurons initiate "top-down" executive control. Your PFC is "wired" (by nerve fibers and connections) to every other part of the nervous system, including the brain's memory. It can access your past and to a very large extent, it is constantly computing your future. We know much now about the PFC from cases where it has been disconnected from the rest of the brain - the Prefrontal Lobotomy that was popular during the late 1930's and in the 1940's and also certain famous industrial accidents where the PFC has been damaged.
   Let us look at some cases that illustrate PFC damage. Typically, a patient who had PFC damage; when he prepared his cup of coffee, first stirred and then added cream and sugar. Also the PFC damage causes dis-inhibition with lack of behavioral control that leads to impulsive, often weird behavior. For example, while waiting in a doctor's inner office for the doctor, a PFC-damaged patient, noted the doctor's comb on the desk so he picked it up and combed his hair. Even worse, he saw a handheld urinal on a table and, needing to urinate, went ahead and was nonchalantly using it as the doctor returned. Another such patient, sitting in a dark movie theater noticed that the stranger sitting beside him was eating out of an open popcorn container. He liked popcorn too; so, without even asking, he reached in for some of the stranger's popcorn. You can imagine the trouble that followed. Typical of these patients, they are not embarrassed by their inappropriate behavior. It is as if they do not really care any more. Thus they have been described as almost inhuman in their loss of empathy for others.
   More recently it has come to be understood that this type of impulsive, seemingly thoughtless, bizarre behavior is basically the result of loss of much of the working memory which is located in the orbitofrontal and pre frontal cortex medial part. Recall that working memory is that initial short-term memory (Like RAM in a computer) that, unless paid attention to immediately, lasts only a few minutes. Just think! If your short-term working memory got lost or degraded because of a defective PFC, then the immediately previous experiences would become lost so you would seem to act on impulse because you have nothing to compare in the past to warn you of the inappropriateness of what you are about to do.
   The defects from PFC damage are remarkably like what family and friends describe in the social relations with schizophrenics and as parents describe with autistic and ADHD children.
   How to benefit from the knowledge? First, protect your PFC. This means protecting the head from lifelong frontal head bangs by being alert and by use of a long visor cap when walking. It means keeping the brain well nourished and oxygenated with low cholesterol and good respiratory function (no smoking). It means avoiding psychosurgery involving the PFC. Also make it a good habit to review your past life in a psychoanalysis as described in 9.33 Psychoanalysis - Secret of Do It Yourself.
Mind - What is It?  Finally we end with Mind, because the PFC is the executive center of the Mind.
A mind is awareness of self and others. As each reader who becomes a student of the nervous system should see, this starts with electrical and chemical connectivity between the neurons and our external environment. What makes the inner workings so hard to understand is the huge complexity of the connections, the signalings and the responses. As the data accumulate, it does seem like the saying: "We are like robots who react by getting our buttons pushed (bottom up) and by anticipating our environment (top-down) is, in a tremendously complex way, accurate. The human nervous system is vast arrays of neural nets interacting with environmental stimuli to accomplish what most prolongs the body's life and above all what best works to maintain and to pass-on its unique DNA to the future. And the mechanism works by an incredible number of reflexes, conditionings and anticipatory neural responses based on past life experiences. In the complexity, each of us becomes a free-will individual because the choices are, almost, infinite. But, before infinity starts, the individual consciousness becomes predictable; still, no one has such a computer to accomplish the prediction; so, in effect, we are free agents in a world we never made, and, especially nowadays, we must re-make it fast or we may too-soon end up becoming a dead-end part of its past.
END OF CHAPTER. To read next click 9.8a Neurology of Sensation and Perception


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