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Chapter 15

"Hiya!" Mindy broke into Lovejoy's reverie.

"Hello."

"Were you meditating?"

"Sort of. This is a beautiful place."

"Especially on a day like today."

"So, you're going to tell me about human thinking today?"

"Well, I don't really think you can handle it on top of yesterday's lecture."

"Really! You didn't come all the way over here this morning to tell me that."

"I'm not a good liar. Do you remember where we left off?"

"Sure. Animals discover and understand the outside world through their interaction with it, the emphasis being on 'action'. The muscles used for action also give the necessary feedback to model the world. This modeling relies heavily on data from the muscle sensing system, what you're calling the Pro-system. Some evolutionary lines of animals emphasized this modeling ability to help them predict the results of their actions and thus survive. The great apes have made thinking their selective advantage and, not coincidentally, have developed the Pro-system disproportionately well."

"Very good. You've been mulling this overnight, I suspect. Eventually this 'thinking' process was carried out more and more completely by subsections of the motor system within the brain, not out in the body; for example, in the secondary motor areas and also the cerebellum, the 'little brain'."

"I thought that was used for coordination."

"It turns out that it's important in our cognitive functions and in attention disorders such as autism.[17] The cerebellum is highly ordered and is arranged more like a computer than other parts of our brain. It has too many fibers going to the cortex to be only used for coordination. My guess is that this is the muscular subsystem where the calculations for modeling are performed. But it's not crucial whether or not it's the cerebellum. During our thinking, the connections to the muscles are very active. So body language is obligatory, unless we specifically try to hide it. Conversely, we can influence our state of mind by shifting our body, its posture and the tension in our muscles."

"You know I did that today. I was sitting with Dr. Callahan, head honcho at the hospital where I was interviewing. He was grilling me not just on my training but also on a particular case he'd had that day and how I'd handle it. I think he needed help. Anyway I became anxious and really just wanted to leave. My left leg was crossed on my right knee like this, and I felt it tensing up. I realized that the muscle which was tensing more and more as I wanted to leave, was also the first muscle that I would use to uncross my legs in order to get up and leave."

"Right. The muscle was linked to your thought about leaving."

"As soon as I mentally took control of that muscle and relaxed it, the urgency to leave eased."

"You modified the unconscious neurological processing by modifying your muscles. The reverse of body language."

"Then I started paying attention to my breathing. I breathed deeply and naturally. After that I didn't care whether he approved of me or not. He became unimportant. In fact, when I was less defensive, I could appreciate aspects of him that I liked. He's friendly enough as long as he feels in control."

"It's funny you mentioned breathing because the muscles of the diaphragm are among the few in the body with connections to both the conscious muscular system and the autonomic nervous system. You can use this crossover to consciously calm down the fight or flight reaction system."

"You mentioned conscious. But where in your thinking model does human consciousness come in?"

"That's comes later."

"Does it take long?"

"I spent the last twelve years working out the neural pathways for this and you want it brief? OK, I'll do my best. We can fill in the gaps later if you ask the right questions."

"I promise to ask questions. Whether or not they're the right ones, I can't guarantee. In fact, before we get to humans I have a few questions about your theory."

"OK."

"I get that we model the world internally, on some part of the nervous system related to muscles. But who does the thinking? I mean if you have an internal model, do you also have an internal 'you' who decides when you've found the best action to take?"

"No! Specifically not. That would just transfer that problem of thinking to some other place. Probably the best way to conceptualize this is to think of a reflex arc. You touch something hot. The 'hot' signal goes to the central nervous system. If it's very hot, no real 'decision' has to be made. Evolution has engineered into our nervous system an immediate signal to the muscles to withdraw. This is so simple that it actually occurs outside the brain at the level of the spinal cord. Technically, this is still within the central nervous system."

"Right. This doesn't seem much different than an ameba retracting from some noxious stimulus. Something hot, sharp or poisonous; move away." Lovejoy contributed.

"Then there's the opposite. Higher concentrations of food, sugar or whatever is desirable; move toward. Basically, there are opportunities and there are dangers. There are two basic categories of action too. Move towards, and move away.

"Higher animals, us included, have certainly elaborated upon this theme. For example, on the sensory side, our ability to discern dangers and opportunities gets more complex, the more layers of the nervous system we add in. So a rabbit can recognize the shadow of a big bird as a danger. A zebra learns to recognize the outline of a big cat so it can run away. All land creatures can recognize the edge of a cliff as something they want to avoid lest they fall off."

"OK. But how do we recognize things like that? It's not as simple as very hot or very sharp."

"Of course not. The first breakthrough on understanding pattern recognition came from the work on the retina by doctors Hubel and Weisel.[18] They showed how the first layer of nerve cells going from the retina simply turned on or off depending upon whether or not light was hitting the cell or not. But the next layer of nerve cells received connections from the first layer. The cells at this layer would be turned on if, for example, one cell in the preceding layer was active, or turned on, and the cell next to it was off. So the second layer of cells only registered an interface, an edge between light and dark. Then the third layer of cells would register if there was a whole line of edge cells turned on. You could say that this layer distilled information to develop the concept of a line. Except nobody's thinking or calling it a line yet. The cells are just arranged in such a manner that they turn on if there's a line of light/dark shining on the retina. Evolution has lead to the development of creatures that can distinguish such things as lines. This extraction capability becomes more complex and leads to the ability to recognize a wide variety of things 'out there' in the world; which enhanced survival value."

"Actually I've heard of this work. I believe they won the Nobel prize for it. Weren't there cells that only turned on if there was a vertical line, and others for horizontal lines, and others for different angles in between."

"Exactly. Each layer of neurons distills the sensory information progressively. The way the neurons are connected determines what type of information will be distilled out of the raw data. And these became the rudimentary forms of 'concepts'."

"I've never thought of them as concepts before." Lovejoy said.

"So take that layering process with thousands and millions of layers. Our brain can select out very specific combinations of sensory input to get the idea of an animal big enough to attack, or the edge of a cliff, or whatever."

"But there's a big difference between distilling out a line at 45 degrees to the horizon and a very flexible concept of a jaguar."

"Absolutely. And there's certainly much research to be done. But some of it's already been done. For example there's a neurological structure called a 'cortical column'. It's sort of a dome of nerve cells in the outer layer of the cortex, the most advanced part of the brain. It seems as if these columns represent a distinct location for the distillation of concepts. The nerves in one column, or a specific network of columns, becomes active when all the criteria necessary for a jaguar, or a cliff edge are met."

"That would imply that the concepts that we use to think about the world are already determined before we are born." Lovejoy thought out loud.

"Not necessarily. It's how the connections of nerves lead into a column that determines when it will light up. And these connections can change over time with learning. There may be concepts that evolution has found always to be useful which could be genetically determined. In fact, there's evidence that babies are born expecting to find a face with eyes, nose and mouth that they can study, learn the details of, and call it 'mother'. There is also evidence that language has certain basic structures which are determined genetically." Mindy continued. "On the other hand, whose to say whether or not some of these cortical columns are kept available to be programmed at a later time, like the first several years of our lives. We know that babies make more brain cells at least for two years."

"Or maybe some combination of the two. Nature may have the basic neural structure describing our family, but we fill in the details as we grow up." Lovejoy contributed.

"Fine. But I don't want to get into another discussion. The point is that we distill our sensory input into various concepts. And those concepts don't always have to be things. They maybe more abstract such as a source of food, source of water, attacking predator, stationary danger.

"The concepts can be combined in a variety of ways to give what I call 'situations'. By situation, I mean a snapshot of everything important around us, and what each thing is doing. This leads to nerve stimulation of all those things which are associated with the particular elements of the situation, such as other people, various opportunities, and more abstract concepts and emotions. Also sometimes our associations are triggered only when we have a particular combination of things. The full assessment of a situation is completely in the associative connections.

"Once the situation is assessed," Mindy continued, "the muscular reaction to that situation begins. The very basic categories are derived from our primitive ancestors, like you suggested before. Danger - move away; opportunity - move toward. But these plans of action have progressively more complexity and specificity as we evolve. The muscular system does what the sensory system does, only in reverse. It starts with a general response, and has to work out an acceptable, detailed plan of action.

"But how does it do this? Induction is not the same as deduction." Lovejoy pointed out.

"Well it's simple really. Nature devised a technique of testing its proposed actions. Basically, the motor cortex sends out initial signals for a set of actions to respond to the situation. The first trial set of actions chosen are probably basic; and determined partly by heredity, such as withdrawal reflexes in a baby. But these are quickly superseded by previously successful responses, learned essentially through trial and error and later taught by adults to children.

"So, we make a plan of action. The nerve signals go out to the entire muscular system, but at a low level. Not quite enough to stimulate the muscles into a full series of orchestrated actions. But enough to cause certain muscles to tense up a little.

"The Pro-system senses the new tension in specific muscles. This new sensory data is fed back into the model. The model, based upon experience, computes how the current situation would change if those specific movements were carried out. It can do this because the world model was built from its muscular movements within the real world.

"If the resultant calculated situation represents less danger or more opportunities than the previous situation, the nerves leading to this action receive more stimulation. Conversely, if the new situation has more danger or less opportunity, the stimulus for that plan of action becomes less intense, or perhaps even inhibited and the system drops back to the initial situation.

"I call this the 'thought-muscle loop'. This loop uses the Pro-system, the internal model and the entire muscle system. It continues to cycle until the current plan of action, through repetitive positive feedback from a combination of greater opportunities and lessened dangers, is stimulated enough to trigger full action."

"This is brilliant!" Lovejoy exclaimed. "You've devised a servo-system which automatically develops a plan of action, evaluates it by modeling how the world will change as a result of the proposed action, and raises the level of nerve activity sufficient to bring about the complete series of muscular actions if the plan continues to look good, or suppress it if it doesn't."

"I didn't devise it. Nature did."

"But what about memory... And emotion? What about free will?

"Hold on! The system of explanation I've been working on is powerful. But it's not everything." Mindy clarified for him. "I've been describing what we call cognition; thinking. Memory includes the process of strengthening connections between neurons. So connected events in the real world are represented by stronger and stronger nerve bridges in the brain. The system that replays events over and over in our brain, so that the nerve connections become stronger and stronger, is the memory system; the hippocampus and amygdala and related structures. This strengthens important associations in our brain. But thinking is how we use those associations to mold useful plans of action."

"And emotion?"

"You know we humans make distinctions between these systems of the brain, but nature grows things organically, progressively. So in a sense our distinctions are artificial. Historically we have tended to separate our studies of thinking and emotion, but emotion is crucial for the cognitive function. Without emotion we might accurately assess a situation but we would not respond to it appropriately. Research on individuals with certain brain injuries in areas related to emotion show that.[19] With unlimited symbolizing capability, we can make any thought link to any other thought. But it's our emotion, in the grander definition, which places values on things and helps us use logic in a meaningful way."

"Emotion can also overwhelm common sense, it seems to me." Lovejoy challenged.

"Yes. It works both ways. A proper balance seems to be necessary for what we consider normal functioning."

"Why does emotion last so much longer that thought? I can get involved in an argument, be very angry, and then resolve the issues intellectually. But after that I'm still shaking and ready for a fight." Lovejoy asked.

"The emotional centers trigger a whole host of reactions; some to nerves that later play into our intellectual analysis, and some to cells that secrete hormones. These hormones go into the blood stream and activate other parts of the brain or even entire organ systems. This has a momentum of its own and takes awhile to calm down after the last hormone is secreted."

"Aren't changes in the organ systems sensed by the body's interoceptive system?"

"Yes."

"Well, the interoceptive system is kind of like the Pro-system; only instead of the muscles, it tells the brain what state the body's organs are in. Do you see any role for interoception, or maybe we should call it the 'Int-system', in your thinking loops?" Lovejoy wondered.

"Not really. The feedback is too slow. The feedback via the pro-system is all through nerves. The computation of thinking and planning needs feedback at the speed of electricity. The 'Int-system' as you call it, would be too reliant upon hormones traveling through the bloodstream to be involved in the computation of modeling our universe. Though I do believe it's involved in maintaining a general tone for how we evaluate a situation.

"When we talk about emotion, isn't there a difference between the subjective experience of feeling and the objective description of how that experience is produced?"

"Sure. But that's true whenever one talks about thinking." Mindy agreed. "It's easy to accidentally flip back and forth between these two ways of talking about it. Understanding subjective and objective is crucial to understanding consciousness, or as I prefer to call it, self-consciousness."

"So are we talking about human thinking yet?

"Soon. If we get to the distinction of subjective and objective, that would bring us into human thinking."

"Can we take a break?" Lovejoy breathed. "I want to think about what you've said. It's beautiful, it really is. But I need to absorb it before we go on. Anyway aren't we going to meet with the E-group this evening."

"At six. We're meeting at Howard's house. Do you want directions? Or, I can take you."

"What time is it?"

"Quarter 'til five.

"Actually I'd love to go with you. I'm just wondering, is there a chapel nearby; or synagogue or some sort of quiet place I can go to for a while?"

"I thought you were burned out on that religious stuff."

"I am a little jaded with the organizations, but I still find it useful to meditate, pray or make some sort of connection."

"To what?

"Look, if you like, feel free to come along."

Soltrey@humanmind.net is copyrighted July 2000.  All rights reserved B.T. Brian Brown.