"How does the meat of the brain give rise to the spirit of the mind?"
Dr. Rodolfo Llinas^*

The brain is a proactive system allowing us to learn from the past, assess the present and predict future time and space. The inherent abstract capabilities of the brain enable us to be more adaptive in our world.

The brain has evolved with an improved adaptive capacity. In this process, newer structures have evolved upon older, lower functions. The final result is a hierarchy of more complex, adaptive systems existing over a lower, more primitive system. The lowest, most basic function is the Brain Stem and Hypothalamus that modulates vegetative functioning. The next level is the Limbic System, which modulates emotional functioning. The Para Limbic areas facilitate emotional association functioning. The Cerebral Cortex controls processing or association. Three basic functions are Perceptual (afferent) Processing, Motor (efferent) Processing and Complex Processing (executive functioning).

Humans possess unique, creative adaptive capabilities. The most advanced, most complex-associative, most creative, most adaptable to novel situations and the most uniquely human part of our nervous system is in the tip and most forward portion of the brain-the tip of the pre-frontal cortex.

A part of the basic wiring of the brain is a stimulus-response model. The stimulus from the internal and/or external environment elicits a response toward the internal and/or external environment. The more advanced portions of the brain allow for more complex adaptations. All of the different adaptive systems act together with a hierarchy of simultaneous inputs leading to a hierarchy of simultaneous responses.

The brain and nervous system, as Plato describes in his metaphor, operate on a push-pull basis. There is a simultaneous stimulation of opposing circuits. Different functions are stimulated and inhibited at the same time. The degree of balance between two or more opposing pathways determines the final outcome.

Modulation coordinates multiple stimulatory, inhibitory functions, thereby, facilitating complex adaptation. It alters the state an organism is in just as the control knobs of a TV set alter brightness, contrast, volume, etc. Biological modulations can be very complex. To modulate the body, besides the peripheral nervous system, the autonomic and endocrine systems are also involved. For example, when a threat is perceived, there is a modulation to perceive relevant cues to prepare for a fright, flight or fight response. Different parts of the brain, the autonomic and endocrine systems all modulate in synchrony to help adapt to this current environmental condition. Resources are allocated from one group of functions and shifted towards other functions as when systems functioning during periods of quiescence are reduced and stress system functioning is increased. Modulation, therefore, can be reduced to a complex form of stimulation and inhibition.

There are many different types of modulation, most of which are poorly understood. All of us possess a different modulation capability; some of us allocate more energy to introspection vs. vigilant scanning, for example. The more complex the modulation, the greater the capacity to adapt to unique situations.

Besides hierarchy, stimulus-response, simultaneous stimulation-inhibition and modulation, another concept is memory. Memory is a significant function in both the nervous system and the immune system. In the nervous system, memory creates a long-term potential similar to ruts in the road. The more strongly an associative network is stimulated, the stronger the long-term potential, or memory.

Memory is the result of a sequence of positive and negative feedback events. Emotional memory is a particularly strong function. The current effect of prior emotional learning often is stronger than our cognitive learning or our capacity for current cognitive or emotional processing. Since memory constantly changes, the brain is in a constant state of change or it is considered to be plastic.

As we place these concepts into a psychodynamic model, we see five basic components to the nervous system:

• 
  
• Afferent or sensory systems
  
• Modulation systems:
  

  -The greater limbic system
  -The lower level centers modulating basic vegetative functioning

• Processing centers
  
• Efferent or output systems

There is a hierarchy of systems within each one of these five components. At the top is the conscious, creative process which considers and balances emotional, cognitive, internal perceptions (enteroreceptive), external perceptions (enteroreceptive), instinctual and memory inputs and outputs.

We can compare the brain to a symphony orchestra. Many components are acting in synchrony to hopefully achieve a harmonious end result. We would like to see ourselves as having total conscious control over our behavior. However, our responses are strongly influenced by instinct, memory, environmental influence and various pathological states.

Which is more powerful in influencing our behavior, higher powers or lower powers? Is there a top-down hierarchy or a bottom-up hierarchy? Is the pre-frontal cortex more powerful than the hypothalamus and limbic system or is the opposite true? Pathways from the cortex to the amygdala are less well developed than pathways from the amygdala to the cortex. The lower powers have been present in evolution for a much longer period of time, leading us to believe they are much more powerful thus causing more of a bottom-up hierarchy (i.e.: emotions drive thoughts more so than thoughts drive emotions). Lower life forms can function with emotional reactivity, without logic or language. Emotional reactivity is a much more basic, vital function than is the higher power of logic and language.

This view may, however, conflict with the manner in which we would like to view ourselves. Once we use this framework, we can better understand that altered emotional states often drive the thought content in that direction. For example, a spontaneous panic attack creates an emotional state that then causes higher powers to entertain thoughts of imminent harm. With a failure of counter-regulatory systems, these thoughts then intensify the emotional and physical state, causing a vicious cycle that results in a full-blown panic attack. In this instance, there is a bottom-up hierarchy with lower powers being more powerful.

True, higher powers impact and sometimes direct lower powers as described in Plato's model of the charioteer, but are the lower powers more powerful? This is, of course, a question for endless debate.