Winston ChurchillThe only thing to fear is fear itself.
Each person that contributes to a field has his/her own perspective, based on vocation, educational discipline, and goal. My own multidisciplinary background comes from the field of systems physiology.
Systems physiologists are trained for and indeed thrive on investigating complex systems. Simple models help us understand the behavior of biological systems only to a point. The reality is that the simplest of living organisms are a challenge for the best of minds. As humans, we are only capable of pondering about 6 facts simultaneously, and yet living beings operate systems that have many more inputs and outputs. Higher order systems are even more complex.
Nowhere is this more apparent than in the last frontier of medical understanding - the human brain. On another thread, Jim quite aptly described that organ as an entity with layers and layers of evolutionary complexity. One would think that a wise creator putting something like this together may have done better doing so from scratch. What is apparent from looking at its structure is that one can view evolutionary progress from the core (the brain stem) to the periphery (the cerebrum). It almost reminds one of the backward compatibility problems that some chipmakers contend with when evolving from generation to generation. And yet with all its odd pasting of layer upon layer, the system works remarkably well.
Take fear. Most lay people considering the element of fear in life/death situations to be driven by the amygdala. But primates have at least three centers that manage fear and the physiologic response to it:
Prefrontal cortex - This region in the front of the brain participates in the interpretation of sensory stimuli and is likely an area where the potential for danger is assessed. Within that region is an area known as the orbitofrontal cortex. This region is much more prominent in primates than in rodents, and therefore has only recently been studied in detail. It is thought to maintain long-term, habitual behavioral responses, modulate emotional responses, and enable the prediction of the consequences of future behaviors.
Amygdala This is part of a very primitive area in the brain called the limbic system. Both have been implicated in generating fear.
Hypothalamus This region at the base of the brain is responsible for secreting corticotropin-releasing hormone. That hormone in turn elicits a cascade of effects on the pituitary and adrenal glands, which in turn negatively inhibit its action via the amount of the final product (cortisol) released.
Each of these centers are electrically connected to the next with a high degree of complexity. Moreover, they are also connected hormonally in that they each respond to various neurotransmitters in unique ways.
More later...
- Bill
