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"ENTRY POINT LOCALIZED."


The patient did not move, made no sound. The brain could not feel pain; it lacked pain sensors. It was one of the freaks of evolution that the organ which sensed pain throughout the body could feel nothing itself.

Ross looked away from Ellis toward the X-ray screens.

There, in harsh black and white, she saw the crisply outlined white electrode array begin its slow, steady movement into the brain. She looked from the anterior view to the lateral, and then to the computer-generated images.

The computer was interpreting the X-ray images by drawing a simplified brain, with the temporal-lobe target area in red and a flickering blue track showing the line the electrode must traverse from entry point to the target area. So far, Ellis was following the track perfectly.

"Very pretty," Ross said.

The computer flashed up triple coordinates in rapid succession as the electrodes went deeper.

"Practice makes perfect," Ellis said sourly. He was now using the scale-down apparatus attached to the stereotactic hat. The scaler reduced his crude finger movements to very small changes in electrode movements. If he moved his finger half an inch, the scaler converted that to half a millimeter. Very slowly the electrodes penetrated deeper into the brain.

From the screens, Ross could lift her eyes and watch the closed-circuit TV monitor showing Ellis at work. It was easier to watch on TV than to turn around and see the real thing. But she turned around when she heard Benson say, very distinctly, "Uh."

Ellis stopped. "What was that?"

"Patient," the anaesthetist said, gesturing toward Benson.

Ellis paused, bent over, to look at Benson's face. "You all right, Mr. Benson?" He spoke loudly, distinctly.

"Yuh. Fine," Benson said. His voice was deeply drugged.

"Any pain?"

"No."

"Good. Just relax now." And he returned to his work.

Ross sighed in relief. Somehow, all that had made her tense, even though she knew there was no reason for alarm.

Benson could feel no pain, and she had known all along that his sedation was only that - a kind of deep, drugged semi-sleep, and not unconsciousness. There was no reason for him to be unconscious, no reason to risk general anaesthesia.

She turned back to the computer screen. The computer had now presented an inverted view of the brain, as seen from below, near the neck. The electrode track was visible end on, as a single blue point surrounded by concentric circles.

Ellis was supposed to keep within one millimeter, one twenty-fifth of an inch, of the assigned track. He deviated half a millimeter.

"50 TRACK ERROR," warned the computer. Ross said, "You're slipping off."

The electrode array stopped in its path. Ellis glanced up at the screens. "Too high on beta plane?"

"Wide on gamma."

"Okay."

After a moment, the electrodes continued along the path.

"40 TRACK ERROR," the computer flashed. It rotated its brain image slowly, bringing up an anterolateral view. "20 TRACK

ERROR," it said.

"You're correcting nicely," Ross said.

Ellis hummed along with the Bach and nodded.

"ZERO TRACK ERROR," the computer indicated, and swung the brain view around to a full lateral. The second screen showed a full frontal view. After a few moments, the screen blinked

"APPROACHING TARGET." Ross conveyed the message.

Seconds later, the flashing word "STRIKE."

"You're on," Ross said.

Ellis stepped back and folded his hands across his chest.

"Let's have a coordinate check," he said. The elapsed-time clock showed that twenty-seven minutes had passed in the operation.

The programmer flicked the console buttons rapidly. On the TV screens, the placement of the electrode was simulated by the computer. The simulation ended, like the actual placement, with the word "STRIKE."

"Now match it," Ellis said.

The computer held its simulation on one screen and matched it to the X-ray image of the patient. The overlap was perfect; the computer reported "MATCHED WITHIN ESTABLISHED LIMITS."

"That's it," Ellis said. He screwed on the little plastic button cap which held the electrodes tightly against the skull. Then he applied dental cement to fix it. He untangled the twenty fine wire leads that came off the electrode array and pushed them to one side.

"We can do the next one now," he said.

At the end of the second placement, a thin, arcing cut was made with a knife along the scalp. To avoid important superficial vessels and nerves, the cut ran from the electrode entry points down the side of the ear to the base of the neck. There it deviated to the right shoulder. Using blunt dissection, Ellis opened a small pocket beneath the skin of the right lateral chest, near the armpit.

"Have we got the charging unit?" he asked.

The charger was brought to him. It was smaller than a pack of cigarettes, and contained thirty-seven grams of the radioactive isotope plutonium-239 oxide. The radiation produced heat, which was converted directly by a thermionic unit to electric power. A Kenbeck solid-state DC/DC circuit transformed the output to the necessary voltage.

Ellis plugged the charger into the test pack and did a last-minute check of its power before implantation. As he held it in his hand, he said, "It's cold. I can't get used to that." Ross knew layers of vacuum-foil insulation kept the exterior cool and that inside the packet the radiation capsule was producing heat at 500 degrees Fahrenheit - hot enough to cook a roast.

He checked radiation to be sure there would be no leakage. The meters all read in the low-normal range. There was a certain amount of leakage, naturally, but it was no more than that produced by a commercial color television set.

Finally he called for the dog tag. Benson would have to wear this dog tag for as long as he had the atomic charging unit in his body. The tag warned that the person had an atomic pacemaker, and gave a telephone number. Ross knew that the number was a listing which played a recorded message twenty-four hours a day. The recording gave detailed technical information about the charging unit, and warned that bullet wounds, automobile accidents, fires, and other damage could release the plutonium, which was a powerful alpha-particle emitter. It gave special instructions to physicians, coroners, and morticians, and warned particularly against cremation of the body, unless the charger was first removed.

Ellis inserted the charging unit into the small subdermal pocket he had made in the chest wall. He sewed tissue layers around it to fix it in place. Then he turned his attention to the postage-stamp-sized electronic computer.

Ross looked up at the viewing gallery and saw the wizard twins, Gerhard and Richards, watching intently. Ellis checked the packet under the magnifying glass, then gave it to a scrubbed technician, who hooked the little computer into the main hospital computer.

To Ross, the computer was the most remarkable part of the entire system. Since she had joined the NPS three years before, she had seen the computer shrink from a prototype as large as a briefcase to the present tiny model, which looked small in the palm of a hand yet contained all the elements of the original bulky unit.

This tiny size made subdermal implantation possible. The patient was free to move about, take showers, do anything he wanted. Much better than the old units, where the charger was clipped to a patient's belt and wires dangled down all over.

She looked at the computer screens which flashed

"OPERATIVE MONITORS INTERRUPTED FOR ELECTRONICS CHECK." On one screen, a blown-up circuit diagram appeared. The computer checked each pathway and component independently. It took four-millionths of a second for each check; the entire process was completed in two seconds. The computer flashed

"ELECTRONIC CHECK NEGATIVE." A moment later, brain views reappeared. The computer had gone back to monitoring the operation.

"Well," Ellis said, "let's hook him up." He painstakingly attached the forty fine wire leads from the two electrode arrays to the plastic unit. Then he fitted the wires down along the neck, tucked the plastic under the skin, and called for sutures. The elapsed-time clock read one hour and twelve minutes.



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