Self-discovery

In Lieu of an Epigraph

“The theme of today's lecture is: why does the student sweat at exams? Quiet, comrades! I suggest you take notes — the material is on the subject…. Thus, let us examine the physiological aspects of the situation that all of you present have had to experience. The oral exam is on. The student through various contractions of the lungs, thorax, and tongue is creating air vibrations — answering his question. His visual analyzers control the accuracy of his response by the notes in his hand and by the nods of the examiners. Let us sketch the reflex chain: the executive apparatus of the second signal system utters a phrase — the visual organs register a reinforcing stimulus, a nod — and the signal is passed to the brain and supports the stimulation of nerve cells in the proper part of the cortex. A new phrase… a nod… and so on. This is often accompanied by a secondary reflex reaction: the student gesticulates, which makes his answer all the more convincing.

Meanwhile the unconditioned reflex chains operate on their own, inexorably and unconstrainedly. The trapezoid bone and broad muscles of the back support the student's body in an upright sitting position — as natural for us as the position of walking was for our predecessors. The chest and intercostal muscles maintain rhythmic breathing. Other muscles are tensed just enough to counteract gravity. The heart beats evenly; the sympathetic nervous system has stopped the digestive process so as not to distract the student. and everything is in order.

But now the student registers a new aural stimulus through his eardrums and membranes of the ears: the examiner has asked him a question. I never tire of observing what follows — and I assure you, there is no sadism in this. It's simply pleasant to watch how quickly and clearly, taking the millions of years experience of our ancestors into account, our nervous system reacts to the slightest hint of danger! Look: new air vibrations first bring on the end of the previous activity of the unconditioned reflexes — the student stops talking, often in mid — word. Then the signals from the hearing cells reach the medulla, excite the nerve cells of the rear tubers of the lamina tecti which commands the unconditioned reflex of caution: the student turns his head in the direction of the examiner! Simultaneously the signals of the aural stimulus branch off into the diencephalon, and from there into the temporal lobes of the cortex, where a hurried meaning analysis is undertaken of the air vibrations.

I want to direct your attention to the high expediency level of the location of the analyzers of aural stimuli in the cortex — right next to theears. Evolution naturally took into account that a sound in the air moves very slowly: some 300 meters a second, almost the same as the speed of signals traveling along nerve fiber. Yet a sound could be the rustle of a lurking tiger, the hissing of a snake, or — in our times — the noise of a car careening around the corner. You can't lose even a fraction of a second to transmit the sound through the brain!

But in the present situation the student recognized not the rustle of a tiger but a question posed in a quiet, polite voice. Hah, I think some would prefer the tiger! I assume that I don't have to explain that a question asked during an oral exam is taken as a signal of danger. After all, broadly speaking, danger is an obstacle in the path toward a given goal. In ourwell — ordered times there are few dangers that threaten the basic goals of a living being which are protection of life and health, propagation of the species, and satisfaction of hunger and thirst. That's why secondary dangers — the protection of dignity, respect, scholarships, the opportunity to study and then have an interesting job and so on — take on primary prominence. Thus, the student's unconditioned reflex reaction to danger worked beautifully. Let's see how he reflects it.

In biochemistry lectures you have been familiarized with the properties of ribonucleic acid, which is found in all the brain cells. Under the action of electrical nervous signals RNA changes the continous distribution of its bases: thymine, uracil, cytosine, and guanine. These bases are the letters of our memory; we can write down any information in the cortex of the brain using combinations of them. And so, this is the picture: the question, understood in the temporal sites of the cortex leads to the excitation of nerve cells that take care of abstract knowledge in the student's brain. Weak response impulses arise in neighboring areas of the cortex: “Aha, I read something about that!” So the stimulation concentrates in the most hopeful of these areas, takes it over, and — oh horrors! — there with the help of thymine, uracil, cytosine, and guanine there is recorded God only knows what in long molecules of RNA, for instance: “Drop your studying, Alex! We need a fourth!” Quiet down, comrades, don't be distracted.

And then a quiet panic in the brain sets in — or, less colorfully speaking, a total irradiation of stimulation. The nerve impulses arouse the areas of logical analysis (maybe I'll figure something out!) and the cells of visual memory (maybe I've seen it?). Vision, hearing, and sense of smell sharpen. The student sees with amazing acuity the ink spot on the edge of the desk and a bunch of scribbles, hears the leaves rustling outside the window, someone's footsteps in the hall, and even the whisper: “Guys, Alex is in trouble!” But that's not it. And so stimulation passes to greater and newer parts of the brain — danger, danger — spilling over the motor centers in the frontal convolution, penetrating into the midbrain, the medulla, and finally, into the spinal cord. And here I want to move away from the dramatic situation to sing the praises of the soft grayish white growth about a half meter in length that penetrates our spine to the waist — the spinal cord.

The spinal cord…oh, we are greatly mistaken if we think that it is nothing more than an intermediary between the brain and the body's nerves, that it is subjugated to the brain and can only control a few simple reflexes of natural functions! It's still a moot point as to which is subordinate to which! The spinal cord is an older and more venerable process than the brain. It saved man in those days when his brain wasn't developed enough, when in fact he wasn't yet man. Our spinal cord guards memories of the Paleozoic, when our distant ancestors, the lizards, wandered, crawled, and flew among giant ferns; of the Cenozoic, the period when the first apes appeared. It has sorted and stored synapses and reflexes proven over millions of years to be effective in the struggle for survival. The spinal cord, if you will, is our inner seat of rational conservatism.

Of course nowadays, that old cord of man, which can react to the complex stimulation of contemporary reality in only two positions — saving life and propagating the species — can't help us out all the time, as it did in the Mesozoic Era. But it still has influence on many things! For example, I would posit that it is the spinal cord that often determines our literary and cinematic tastes. What? No, the spinal cord is not literate and does not contain any special reflexes for viewing film. But, tell me, why do we soften prefer detective movies and novels, no matter how poorly they are made or written? Why do so many of us like love stories — everything from jokes and gossip to the Decameron? Because it's interesting? Interesting? Why is it interesting? Because the firmly engrained instincts for survival and propagation encoded in our spinal cords force us to gather information — what can you die of? — so that we can save ourselves in that situation. How and why does happy and true love come about, the kind that results in offspring? What destroys it? — so that you don't blow it yourself. And it doesn't matter that such a dangerous situation may never come up in your safe, comfortable lives. And it doesn't matter that there is love and more descendants than you know what to do with — the spinal cord tows its line. I'm not going to call these desires in the viewer and reader base, as so many critics do. Why? These are healthy, natural desires, admirable desires. If cows in their evolution ever learn to read, then they'll also begin with mysteries and romances.

But let us return to the student whose brain failed him in responding to the examiner's question. “Ah, you greenhorn,” the spinal cord seems to say to its colleague as it receives the panic signals and goes into action. First, it sends signals to the motor nerves of the entire body; the muscles tense into a position of readiness. The primary sources of muscular energy — adenosine triphosphate and phosphocreatine — break down in tissue into adenosine diphosphate and creatine, releasing phosphoric acid and the first amounts of heat and energy. And I want to direct your attention once more to the biological expediency of raising muscle tone. After all, danger in the old days required quick energetic movement, to leap away, strike, bend, climb a tree. And since it is not yet clear which way you will have to jump or strike, all the muscles are brought into readiness.

Simultaneously, the sympathetic nervous system is also stimulated and begins to command the whole kitchen array of metabolism in the organism. Its signals reach the adrenal gland, which throws adrenaline into the blood, stimulating everything. The liver and spleen, like sponges, squeeze out several liters of extra blood into the circulatory system. Blood vessels expand in the muscles, lungs, and brain. The heart beats faster, pumping blood into all the organs, and with it, oxygen and glucose. The spinal cord and the autonomous nervous system prepare thestudent's bodyforheavy, fierce, and long fighting for life or death!

But the examiner cannot be stunned with a cudgel or even with a marble inkwell. And you can't run away from him either. The examiner won't be satisfied even if the student, overflowing with muscular energy, performs a handstand on the desk instead of answering the question. That's why the secret, stormy activity of the student's organism ends in a useless burning up of glucose in the muscles and heat generation. The thermoreceptors in different parts of the body send hysterical signals of overheating to the brain and spinal cord. And the brain responds in the only way it knows — by expanding the vessels of the skin. Blood rushes to the skin (incidentally, also causing the student to blush) and heats up the air between the body and the clothes. The sweat glands open up to help the student with evaporation of moisture. The reflex chain, stimulated by the question, is finally over.

I'm sure you will make your own conclusions about the role of knowledge in the correct regulation of the human organism in our complex environment, and about its role in the regulation of the student organism at our next session…”

From a lecture by Professor V. A. Androsiashvili in his course, Human Physiology.