The Mind and the Brain

• philosophers have long debated the question of the relationship between the "mind" and the brain.  Descarte in particular is associated with the idea that the mind is something quite distinct from the brain.  Not all peoples believed that the mind was in the brain;  I've heard that the ancient Egyptians did not bother to preserve the brain in mummies because they didn't see any use for it.
• in Descartes' view the rational soul was an entity distinct from the body which made contact with the body at the pineal gland.  The mind could influence the body, as well as the body influencing the mind.  He was interested in the brain and nervous system, as well as in the logic of thought, did a lot of research on reflexes and physiological psychology.
• today, complex systems theory gives us an understanding of how something as complex as the mind can emerge from the interaction of comparatively simple components.
• we will look first at some basic information about the brain and how it works, then at a model of how the mind works which is rooted in complexity theory.

• a basic issue here is "granularity" - do we look at the microscopic components - neurons and neurotransmitters - or do we look at the 100 or so major components or something in between.  The tendency has been to look at the macrosctructure or the microstructure but not so much in between
• basic cellular unit is the neuron, which is similar to nerve cells throughout the body
• connected through dendrites which are analogous to wires
• electrical signals cross a small gap between dendrites called a synapse when charge is high enough
• interaction of neurons in networks is probably more important than the nature of the individual neurons - this gets us to a higher level of granularity
• Hebb's theory:  groups of neurons called "cell assemblies" establish repeatable patterns which are the mind
• the brain is also organized into about a hundred larger units.  Over a long period of years, scientists have figured out what many of the components of the brain do. often by studying the effects of injuries to the brain or by measuring brain wave activity or by stimulating parts of the brain electrically.  Today we have the capability to scan the brain and determine what parts are most active during various activities.  It is not possible, however, to correlate the shape of the head or the size of the brain with behavioral characteristics, as phrenologists tried to do.
• we can also group these 100 major components into about 20 groups (the rows on the Whole Brain Atlas Table), or we can divide it into even larger groupings.  On the largest level of organization, we can observe that the brain is divided into two hemispheres.  Some people see this bicameral division as significant:  "left brain" (logical, analytic) vs. "right brain"  (spatial, synthetic)
• The brain can also be divided into the forebrain, the mid brain and the hind brain.  In this view of the parts of the brain:  the hind brain corresponds most closely to the brain of reptiles and is sometimes called the "reptilian brain".  It is responsible for autonomic functions, keeping the body functions going.  The mid brain is more mammalian and involved with emotion.  The forebrain is more cognitive, rational, intellectual.
• in mammals like us, the forebrain is subdivided into three parts: the hypothalamus, the thalamus and the cerebral cortex.  The cortex is divided into several parts, the largest of which are known as the cerebellum and the cerebrum, but there are also many obscurer regions like the cingulate gyri and so on.  The cortex is a gray surface layer 1 to 4 mm thick, which is divided into six layers (see diagram).  There are pyramidal neurons which link the layers, providing a form a hierarchical organization.
• the cerebellum  serves mainly to evaluate data regarding motor functions.  The cerebrum, on the other hand, is the seat of intelligence -- it's the integrative center in which complex thinking, perceiving and planning functions occur
• we are only beginning to learn about how the parts of the brain interact, although this may be the key to the mind.  Very recently published research suggests that the key to diseases such as the tremors of Parkinson's disease, severe depression, the hand wringing in obsessive compulsive disorders, and the ringing in the ears of tinnitus may be due to a decoupling of two parts of the brain that normally work in concert:  the cerebral cortex and the thalamus. 
• another surprising recent finding is that mammals are continually producing new neurons, although this was previously thought not to be the case.  This suggests there is hope for us older folks!  Newer neurons may be used for new learning.
• this research was done with macaque monkeys, who were injected with chemicals (bromodeoxyuridine) that, along with other techniques (immunohistochemistry), allowed scientists to distinguish newly created neurons.
• they then killed the monkeys (they don't mention this in their article, but how else could they get such nice slides of their brain tissue?), perfused their brains (passed solutions through slides of them, I think),  and traced the location of cells.  By observing different monkeys at different stages in the process, they could determine where the cells originated (in the syz) and where they went (to the neocortical regions).  If you log onto the Science Magazine site, you can download beautiful color graphics of their slides (click here for a sample) for $5, or read the abstract if you fill out a questionnaire.  It is one of few magazines that charges for its WEB site.
• the fact that new findings like this are released, contradicting the received wisdom in the field, highlights the fact that scientists still have a lot to learn about the brain

• this is a model of "Mind" in the abstract, not just of the human mind.  The fundamental assumption is that the mind is a set of attractors of a complex system - that it results from the interaction of a large number of autonomous parts over time
• these parts can be called "agents".  They have the capacity to transform, create & destroy other agents.  Mind

consists of structures that emerge from systems of intertransforming agents.
• many of these agents act by recognizing patterns in the world, or in other agents
• thoughts, feelings and other mental entities are self-reinforcing, self-producing systems of agents
• these self-producing mental subsystems build up into a complex network of attractors and meta-attractors
• this network of subsystems & associated attractors is a "dual network" in structure; it is structured according to at least  two principles: heterarchy (associations based on similarity) and hierarchy (relationships of control between categories).
• agents pass attention ("active force") to other agents to which they are related
• because of finite memory capacity, mind must contain agents able to deal with "ungrounded" patterns, i.e. agents which were formed from now forgotten agents, or which were learned from other minds rather than at first hand -- this is    called "reasoning"
• a mind possesses agents whose goal is to recognize the mind as a whole as a pattern -- these are "self"
• the structure of the mind - the way it would look if you could take a snapshot of it at one instant, is organized according to two interacting structural archetypes - hierarchy and heterarchy
• the dynamics of the mind - the way it would look if we could see it in action in a video - follows two interacting process archetypes - evolution and autopoiesis.
• this model is too complex to "prove" mathematically, and cannot be fully tested with data about the brain.  It is, however, currently being programmed on a computer, a story we will hear about next week.