Fantastic Voyage II: Destination Brain fv-2

by Isaac Asimov

  Then, even as he watched, it seemed to him that the receptors were moving toward him. He could see them now in greater numbers and could also see that those numbers were still increasing. The receptors and the protein molecules to which they were attached seemed to be swimming through the phospholipid molecules (with a film of cholesterol molecules underneath, Morrison knew), which opened before and closed behind.

  "Something's happening," said Morrison as he felt the ship's own motion through the tiny drag of inertia that remained to them at their thoroughly negligible mass.

  59.

  Kone said, "The surface is gathering us in."

  Dezhnev nodded. "It looks like its doing this." He held up his thick and callused hand, cupping it.

  "Exactly," said Konev. "It will invaginate, make a deeper and deeper cup, narrowing the neck and finally closing it, and we will be inside the cell." He seemed quite calm about it.

  So was Morrison. They wanted to be inside the cell and this was the way it was done.

  The receptors continued coming together, alongside each one of them some molecule - some real molecule - and in among them the feigning molecule of the ship. The cell's surface, like Dezhnev's cupped hand, closed upon them entirely and drew them in.

  "Now what?" said Dezhnev.

  "We're in a vesicle inside the cell," said Kaliinin. "It will grow more acid and the receptor will then detach itself from us. It and all the receptors will then return to the cell membrane."

  "And we?" persisted Dezhnev.

  "Since we are recognized by our electric field as a glucose molecule," said Kaliinin, "the cell will try to metabolize us - break us up into smaller fragments and extract energy from us."

  Even as she spoke, the peptide receptor fell away, uncoiling.

  "Is that a good idea, having it metabolize us?" asked Dezhnev.

  "It won't," said Morrison. "We'll be attached to an appropriate enzyme molecule which will find that we don't react as expected. We won't take on a phosphate group, so it will be helpless and will probably release us. We're not really a glucose molecule."

  "But if the enzyme molecule releases us, won't another enzyme molecule of the same type attach itself to us and try again - and so on indefinitely."

  "Now that you mention it," said Morrison, rubbing his chin and absently noticing the bristles grown since his morning shave, "it may be that the first molecules won't let us go, I suppose, if we won't do the expected."

  "A fine situation," said Dezhnev indignantly, slipping into his local dialect of Russian, as he always seemed to do when excited, and which Morrison always had a bit of difficulty in following. "The best we can expect is that an enzyme molecule either holds us forever all by himself or holds us forever in a relay race as we pass from one enzyme to another indefinitely. - My father used to say: 'To be saved from the jaws of a wolf by a hungry bear is no great cause for gratitude.'"

  "Please notice," said Kaliinin, "that no enzyme molecule has attached itself to us."

  "Why is that?" asked Morrison, who had, indeed, noticed that.

  "Because of a slight change in electric charge pattern. We had to mimic a glucose molecule to get into the cell, but once in, we don't have to be one anymore. In fact, we must mimic something else."

  Boranova leaned forward. "Won't any molecule we mimic be liable to metabolic change, Sophia?"

  "Actually, no, Natalya," said Kaliinin. "Glucose - or any other simple sugar in the body - belongs to a certain molecular configuration, so that we call it D-glucose. I've simply altered the pattern to its mirror image. We have become L-glucose and there isn't an enzyme that will touch us now, any more than any of us are likely to put a right shoe on a left foot. - Now we can move about freely."

  The vesicle which had formed on their introduction to the cellular interior had broken up and Morrison gave up as hopeless any attempt to follow what was going on. Fragments around him were enveloped by much larger enzyme molecules that seemed to embrace them and then relax. Presumably, an altered victim of the enzymatic squeeze was set free to be embraced again by another enzyme.

  It was all happening at once and, Morrison knew, this was only the anaerobic portion of the process (in which no molecular oxygen was used.) It would end by breaking up the glucose molecule, with its six carbon atoms, into two three-carbon fragments.

  A little energy would be produced in this fashion and the fragments would be shunted to the mitochondria for the completion of the process with the use of oxygen; a process in which the universal energy-transfer molecule, adenosine triphosphate (or ATP, for short) would be invested in order to get things started and, in the end, be produced once more in quantities substantially greater than the investment.

  Morrison felt the urge to drop everything and to find a way into a mitochondrion, the small energy factory of the cell. After all, the fine details of mitochondrial processes had still not been worked out - but then he pulled away almost angrily at the thought. The skeptic waves came first. He shouted that to himself, as though trying to force a realization of priorities onto an overly curious brain that was threatening to diffuse its interests.

  Apparently, the same thought occurred to Konev, for he said, "We're finally inside the neuron, Albert. Let's not be tourists. What do you find in the way of skeptic waves now?"

  Chapter 14. Axon

  Those who say "A penny for your thoughts" are usually being overgenerous.

  — Dezhnev Senior

  60.

  Morrison bristled at Konev's order. (It had definitely been that.)

  He indicated his resentment by refusing to respond at all for a while. He continued to stare out into the interior of the neuron and could distinguish nothing he recognized. He could see fibers, convoluted plates, hulks of uncertain size and of no clear shape. What's more, he had a strong feeling that there was a skeletal presence in the cell that held the larger objects - the organelles - in place, but that the ship was slipping past it all too quickly, as though it were in a river racing downstream. The feeling of motion was far stronger here than in the bloodstream, for though there were small objects (debris?) that moved along with them, there were larger objects that apparently remained in place and that they passed rapidly.

  Finally Morrison said, "Look, Yuri, we're moving so quickly that the motion is likely to distort the skeptic waves badly."

  Konev snarled, "Are you mad? We're not moving quickly at all. We're just drifting with the intracellular stream that serves to make certain that the small molecules are all made available to the organelle structure of the cell. The movement is very slow on the normal scale; it seems fast only on our miniaturized scale. Do I have to teach you cellular physiology?"

  Morrison bit his lips. Of course. He had again forgotten how miniaturization distorted his perception. And again Konev was completely right.

  "It might be better, though," said Morrison, fighting for self-respect, "if we changed back to D-glucose and allowed an enzyme to snatch us up. The combined size would slow us down and make it easier to pick up the waves."

  "We don't have to slow down. The nerve impulse travels at a minimum of two meters per second in real velocity and in apparent velocity at our size that's about seventy times the real speed of light. As compared with that, our speed, however great it seems, is trivial. Even if we are moving at the apparent speed of a rocket ship, to the nerve impulse we seem virtually motionless."

  Morrison lifted his arm in surrender and felt furious with Konev. There was such a thing as being too right. He cast a quick sidewise glance at Kaliinin, with the uncomfortable feeling that she would be showing her contempt. She met his glance soberly and with no trace of a sneer. In fact, her shoulders lifted slightly as though to say (Morrison imagined), "What do you expect of a savage?"

  Boranova (Morrison glanced over his left shoulder) seemed oblivious to the exchange. She was busy with her instrument and Morrison wondered what she could be so intent on, considering that the ship's engines were off and they were merely drif
ting with the current.

  As for Dezhnev - with the engines off - he was the one crew member who, in truth, had nothing to do at the moment (except to keep half an eye at the material up ahead in case of an unexpected emergency).

  He said, "Come, Albert, study the skeptic waves and give us some answers. Then we can leave this place. It's extremely exciting being inside a cell for those who like it, but already I am quite certain I have seen enough. My father used to say: 'The most exciting part of any trip is reaching home again.'"

  Boranova said, "Arkady -"

  "Yes, Natasha."

  "Save a few words for tomorrow." Morrison noticed the trace of a smile on her lips.

  "Certainly, Natasha. I suspect an attempt at sarcasm, but I shall do as you say." And though he snapped his mouth shut with an exaggerated click of his teeth, he began to hum very quietly to himself, a tune in the minor mode.

  Morrison felt a little astonished. They had been in the ship now for a little less than five hours - but it felt the equivalent number of days, perhaps years. Yet, unlike Arkady and despite his earlier feelings of terror, he was not ready to leave Shapirov's body. He felt a strong urge to explore the cell and his thoughts rested on the possibility.

  Kaliinin must have been thinking along similar lines, for she said in a soft, introspective tone, "What a shame to be the first people inside the most complex of all living cells and to do nothing at all about investigating it properly."

  "That is exactly -" began Morrison, then thought better of it and let the words dangle.

  Konev swung his arm as though he were driving off hordes of insects. "I can't understand this. We are in the cell and we came here for a specific purpose. Albert, focus on the skeptic waves."

  "I am doing so," said Morrison sharply. "In fact, I have done so. - Look!"

  Konev twisted his head, then unclasped himself, so that he could turn around and peer over the back of his seat. He stared at Morrison's small screen and said, "The waves seem sharper."

  "They are sharper. They're more intense and they show finer oscillations than I've ever seen. Come to think of it, I wonder how fine they can get. Sooner or later, an oscillation, if fine enough, will represent the wobbling of a single electron - and then we have to take into account the uncertainty principle."

  "You forget. We're miniaturized and Planck's constant is nine orders of magnitude smaller for us than it is under standard conditions."

  "You forget," protested Morrison, eager to catch the other in a misstep this time, "that the waves are reduced by that much before they reach us. Those waves are exactly where they should be relative to the uncertainty principle, therefore."

  Konev hesitated a bare moment. "It doesn't matter. We're looking at something now and there's no perceptible uncertainty blurring. What does it mean?"

  "It supports my theory," said Morrison. "This is exactly what I ought to see inside a cell if my interpretation of skeptic wave activity is correct -"

  "That's not what I mean. We began with the assumption that your theory was correct. Now it's no longer an assumption, it's a demonstrated fact, and I congratulate you. But what does it mean? What do those skeptic waves show Shapirov to be thinking?"

  Morrison shook his head. "I have no data - zero data - on the correlation of such waves and specific thoughts. It would take years to gather such a correlation, if it could be done at all."

  "But perhaps the skeptic waves, when this clear and intense, produce an inductive effect on your brain. Are you getting any of your famous images?"

  Morrison thought for a moment, then shook his head, "None!"

  From behind him came a quiet voice, "I'm getting something, Albert."

  Morrison turned. "You, Natalya?"

  "Yes, it's odd - but I am."

  Konev demanded, "What are you getting, Natalya?"

  Boranova hesitated, concentrating. "Curiosity. Well, it's not exactly an image of anything. Just an impression. I feel curiosity."

  "And so you might," said Morrison. "It needs no impression from outside to produce such a feeling under these circumstances."

  "No no. I know what my own thoughts and impressions are like. This is imposed from outside."

  Morrison said, "Do you feel it right now?"

  "Yes. It comes and goes a little, but I feel it right now."

  "All right. What about now?"

  Boranova looked surprised. "It stopped suddenly. - Did you turn off your machine?"

  "I turned it down. Now, you tell me when you feel the sensation and when you don't." He turned to look at Kaliinin, intending to tell her to say or do nothing that would indicate when he turned the machine down or up, but she was staring out at the cell, obviously lost in the marvel of watching the interior of a neuron. He wondered if, at the moment, she heard - or cared - what was going on.

  He turned away and said, "Natalya, close your eyes and concentrate. Just say 'on' when you get the sensation and 'off` when you don't."

  For several minutes, she complied with his suggestion.

  Morrison said to Konev, "Does the machine make a noise when it is turned down or up? Is there anything you can hear or sense?"

  Konev shook his head. "I'm not aware of anything."

  "Then there's no mistake. She's getting the sensation only when the machine is on."

  Dezhnev, who, unlike Kaliinin, had followed everything, said. "But why?" His eyes narrowed. "The brain waves are there whether your machine detects them or not. She should get the feeling of curiosity all the time."

  "No no," said Morrison. "My device filters out all the components but the actual skeptic waves. Without the machine, she just gets a confused mass of sensations, responses, correlations, and miscellany of all kinds. With the machine, she gets only the skeptic waves, which further demonstrates the usefulness of my theory."

  "I don't get anything at all," said Dezhnev, frowning. "Doesn't that destroy your theory?"

  Morrison shrugged. "Brains are complicated mechanisms. Natalya gets it. You don't. For that matter, neither do I. Maybe this particular skeptic wave component fits something in Natalya's brain, not in ours. I'm not going to be able to explain everything at once. - Do you get anything, Konev?~

  "No," he answered, as discontented as Dezhnev had been. "Yet I obtained impressions when we were outside the neuron."

  Morrison shook his head and said nothing.

  Konev burst out, "Can't you get anything but just a vague feeling of curiosity, Natalya?"

  Boranova, "No, Yuri, I can't. Not at this moment. But you remember Pyotr Shapirov. He was curious about everything."

  "I remember, but that doesn't help. Albert, in what direction are we moving?"

  Albert said, "Downstream. It's the only direction in which we can move."

  "No no." Then, in sudden anger, "Is that a joke? Are you trying to be funny?"

  Morrison said, "Not at all. You asked in what direction we were going. What other answer could I have given you? Surely the compass directions have no meaning here."

  Konev said, "All right. Sorry. The stream goes this way here. On the other side of the cell, it goes the other way. It's a circulation. But the nerve impulse goes one way only, from the dendrites to the axon. Are we on the side of the cell that's taking us in the same direction as the nerve impulse or in the other direction?"

  "Does it matter?" said Morrison.

  "I think it does. Can your device tell you in which direction the impulse is traveling?"

  "Yes, certainly. There should be a slight shift in the shape of the waves, depending on whether they are meeting the device head-on or from the rear."

  "And?"

  "And we're moving in the direction of the impulse."

  "Good! A stroke of luck. We're heading for the axon, then."

  "So it would seem."

  Boranova said, "And if we are heading for the axon?"

  Konev said, "Natalya, think! The skeptic waves travel along the surface of the cell. The cell here is wide and relatively large. Th
e skeptic waves spread out over a large surface and are weakened in intensity. As the cell approaches the axon, it narrows. The axon itself is long, a very long tube compared to the cell - and very narrow. The waves must concentrate enormously as they race along that tube and they must grow more intense. What's more, the axon is insulated by a thick myelin sheath, so that the wave energy will not be lost to the outside, but will be kept tightly within the axon."

  Boranova said, "You think, then, that we can receive more effectively in the axon?"

  "Much more effectively. If you can detect curiosity now, it should be overwhelming in the axon. And you might be able to detect what Shapirov is curious about."

  "It may turn out to be totally unimportant," said Morrison thoughtfully. "What if he's curious about why he should be lying there and not moving?"

  "No," said Konev sharply, "that would not interest him. I knew Shapirov well. You didn't."

  Morrison nodded. "That's true enough."

  "All his waking time was consumed with the miniaturization process," said Konev. "All his dreams, too, I suspect. And toward the end, in the last few weeks before the - the accident took place, he was working, thinking, dreaming of the connection between quantum and relativity, thinking of how to make miniaturization and deminiaturization energy-free and stable."

  "Surely," said Morrison, "if that were the case, he must have given some hints as to some of the details of his thinking."

  "No, he was a child in some ways. We knew what he was thinking of, but not whether he was making progress or in what direction. What he loved to do was to present it to us whole, complete. - Remember, Natalya, how he loved to do that? He did that with miniaturization itself. When he finally wrote his paper - it was a young book -"

  Morrison said casually, "Where was it published?"

  Konev sneered. "You know it wasn't published. It had a limited circulation to those who had to know. It's nowhere where you're likely ever to see it."