Untitled Document

The Unified Theory of the Nervous System
and Behavior

Cognitive Philosophy /Brain Theory by Steven Michael Harris

A change in perception that explains the problem with a common kind of assumption

In September or October I attended a lecture at MIT by a Harvard professor (John Assad) where he presented his findings concerning studies of monkeys that were taught to move a cursor from one point to another while the eye was fixated on another target point on a computer screen. The researchers discovered that some cells in a particular region of the brain would fire in a particular way only when the cursor was being moved through the field of view. Various controls were used along with prior knowledge of the fact that that region of the brain is identified as a visual processing center to show that the cells were responding to the perception of movement (rather than reflecting the motor control needed to move the cursor).

In other related experiments the brain cells were monitored while the monkey moved the cursor from point A to B in which the cursor would disappear while it was still being moved to the goal. (The cursor would reappear when it got very close to the target.) Some of the cells that were being monitored in this experiment would fire in a particular characteristic way while the cursor was moving on the screen and then these cells would lose that particular pattern of firing during the period of time when the cursor disappeared from the screen. Some cells were identified in this same visual processing region that would fire in a characteristic way when the cursor started moving from point to point and would continue firing in this way even when the cursor disappeared on the screen.

These were wonderful experiments that provide a lot of information about the workings of the brain. All of the observations (that I just summarized in a simplistic way) were fact.

But a major mistake was made when the evaluation of these observations was presented:

The conclusion was made that the cells that changed the pattern of firing during the movement of the cursor through the visual field were cells that registered (or calculated, or perceived) visual movement of this type. It was taken for granted with these observations that these particular (and relatively few) cells were doing the job of registering visual movement.

A similar conclusion was made about the cells that continued firing when the cursor disappeared that these cells were probably calculating the imagined visualization of movement of the cursor when the monkey struggled to get the cursor to its target (and then get the reward of some fruit juice). This was considered interesting evidence of cells that had the job of dealing with mental visualization of movement (when the actual movement through the visual field was removed).

These conclusions involve ways of speaking about the cells that go from the facts of the experiment to theories about the nature of cells and the way they work. The language used in these theories is wrong and this language interferes with really understanding how the brain works.

Something as complex as the calculation of movement through the visual field or the mental visualization of such movement can not be performed by such a small number of cells. What the cells are doing is just firing on and off (in a characteristic way related to such experiments, granted) and such firings are the same as the firings of just about any cells in the brain, even if the characteristics of such firings can be observed to be related in time to particular events.

Millions of cells starting with the cells connected to the cones in the eye are also involved with such calculations of movement in the visual field, even if they don't ever fire in frequencies that correspond in time to the existence of movement in the visual field. Cells that stop firing in response to visual movement are also a part of such nerve cell decisions that have an effect on the calculating of movement in the visual field (or visualization of same). If millions of cells have a part in such information (and they also have a small part in many other functions of "higher" processing), they have relatively equal portions of such mental processing.

Just because these cells identified in the experiment are the only cells observed in the brain to respond in time and in the character of their firings to the existence of visual movement does not mean these are the only cells involved in the processing of visual movement. Even if an experiment that kills these particular cells results in a disability to register visual movement (along with the inability to find other brain cells that, when damaged, interfere with the same ability); it does not mean that these cells alone are responsible for the perception of visual movement.

It could mean that such information and perception is intersecting in such a small number of cells rather than that such processing is the job and accomplishment of that small number of cells.

Let me explain:

Once again I'd like to use the example of a town phone network.

Consider the entire phone network as one function - the function of town phone service. Every phone call, every phone conversation between all of the people using the phone in that town have a portion of involvement in that function of the existence of phone service and activity in that town. There are operators and technicians and a wide variety of equipment that also share a portion of the existence of phone service in that town. Imagine also that there is duplication of a variety of switching equipment and of lines that carry the phone signals around town.

In this phone system there is a particular small stretch of fiber-optic cable that carries all of the phone signals in the town. At any time that there is phone activity in the town - one phone call late at night or a million calls simultaneously - there are signals being sent through this particular cable. Because of the duplication of land lines and switching equipment and the people involved, there is no other point in the town's phone system where the presence of phone activity somewhere in town is always involving that aspect of the system.

Each of the pieces of equipment involved, and the people involved when phone service exists, have a portion of involvement in making phone service exist.

Observation of no phone in town or piece of switching equipment or particular land line could be used to let you know if phone service exists in that town. A line might be dead but phone service is still getting through. A phone might not be in use but others in town are... etc.

The only point in the system where the existence of phone activity can always be registered is in that fiber-optic cable. That cable is the only part of the system that would totally disrupt service if it was broken. Does that mean that the cable is the place where phone service is processed or registered or calculated? No. That cable has an equal part of the puzzle with every other part of the phone system, but that cable is where everything intersects.

Each cell in the brain has a very, very small part of the processing of any task. Cells that don't fire in a particular instant might be contributing part of the processing too, by the fact of eliminating a line of reasoning - an important decision. (The cell that is not firing is not participating in the qualia, the perception, the consciousness, though.)

To visualize how this system works is very difficult. The first task is to explain which ways of looking at it all are wrong.

To think of an individual cell or group of cells as having the ability to perform some complicated function is to think of the cells as doing some kind of unexplainable magic. This language also leads one to think of the brain as a inflexible hardware that was created through extremely complicated genetics organization. Actually all the cells do the same thing and use the same language to make the system work. The way they communicate creates the brain that evolves in an adult. The logic of the cells grows the brain into that particular form and logic and geography because it is the natural way the communication of the cells will create that form absent of any traumas or factors that would corrupt this self-organization.

This problem with the concept of thinking that cells are accomplishing some complicated task alone as a group in a particular region is another of those fatal flaws of medical biological reasoning. Cells can participate as a small part of many tasks and very great numbers of cells are required for most higher functioning. Regions of the brain that have been identified as the location of this function or that function are just the places where those various functions are intersecting.

This concept gets in the way of many understandings. For instance: regions of the brain have been wrongly recognized as the places where memories are stored or organized but memory is something that occurs in almost every cell and synapse of the brain. The reason this mistake has been made is because there are some regions of the brain with many connections to the rest of the brain that are the location of many higher order "intersections" of processing. The memories are everywhere (in very small pieces of processing) but the most important and obvious intersections of cognition are not everywhere. (And, then again, every cell is an intersection of some piece of cognition in another sense.)

This is very difficult to conceptualize and I will continue to write essays that chip away at making sense of this to others.

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