Health & Fitness By HOLCOMB B. NOBLE

''On a scale from 1 to 10, how much pain are you in?'' a laboratory technician asks Bernard Kingsley.

Mr. Kingsley is lying, cramped, inside a huge magnet, in a space narrow and claustrophobic enough to panic even the brave. A padded cradle, an antenna wrapped around it, envelops his head.

''Six,'' he signals. Increase the pain , orders one of the doctors. Mr. Kingsley's legs, stretched out on a flat board, are raised a bit higher.

''How much now?'' the technician asks.

''Eight,'' indicates Mr. Kingsley.

The magnet emits rhythmical pings. Numbers flash by on computer screens, as activity in Mr. Kingsley's brain is translated into pictures at a rate of 40 images per minute. The doctors and technicians, standing inside a glass-enclosed control room, watch silently.

''How much now?'' the technician asks again.

''Nine.''

It may sound reminiscent of some sort of medieval torture session. But in fact, Mr. Kingsley, a 39-year-old former construction worker, is a volunteer, helping researchers try to understand how pain works and to find better treatments for patients like him.

He is one of the first participants in a groundbreaking new series of studies: lying inside the magnetic resonance imaging machine at the State University of New York's Health Science Center in Syracuse, he is having moving pictures made of the pain cells in his brain.

Until very recently, doctors trying to gauge the severity of a patient's pain have had to rely largely on what the patient communicated -- through anything from a wince to a blood-curdling scream.

But using highly refined diagnostic devices like PET -- or positron emission tomography -- scanning and functional magnetic resonance imaging, or f.M.R.I., scientists have been able for the first time to peer deep into the brain and watch pain at work, ''lighting up'' specific neurons.

In studies of 14 patients, Dr. A. Vania Apkarian and a team of neurologists, physicists and technicians at Syracuse have used f.M.R.I. to locate cell groups in the cerebral cortex that are activated in response to severe pain in the hand, in various back muscles and in spinal cord or nerve tissues.

Dr. Apkarian emphasized that it may be several years before the mountains of computerized data the team has collected can be analyzed and then used to improve or alter treatment.

But, he said, the early results seem highly promising, especially when combined with knowledge of brain chemistry gained during the 1980's and the availability of more effective painkillers.

Other research teams in this country and in Canada are conducting similar studies. Dr. Karen D. Davis of the University of Toronto and Toronto Western Hospital and her colleagues, for example, are using imaging to observe changes that occur in the brain cells of patients suffering chronic pain after a stroke or spinal cord injury. They are also investigating the ''phantom'' pain many patients experience after a limb is amputated.

Dr. Howard Field, a neurologist and pain expert at the University of California at San Francisco, called the work of Dr. Apkarian, Dr. Davis and others ''a major revolution in medicine.''

The research, he said, is helping dispel a number of false notions about pain. He said that some doctors, for example, have believed that it was somehow less worthwhile to devote time and energy toward lessening a patient's pain than it was to treat the underlying disease or injury. And as late as the late 80's, he said, ''the myth persisted that somehow what goes on in the mind, or the cells of the brain, is somehow less scientific or real than what goes on physically in the body.''

But the fact that pain, like blood pressure or body temperature, can now be measured, Dr. Field said, will help convince doctors that patients' pain is very real. And it may give reassurance to physicians who treat the most severe chronic pain , like that of cancer patients. In the past, these doctors have often refrained from giving enough pain medication to relieve suffering out of fear that their patients might become ''hooked'' on the painkillers.

Pain experts say that having better ways to measure pain also will help protect health insurance companies from fraudulent claims, and help policyholders prove that their claims are legitimate.

The first success in capturing a still image of pain in the brain was reported in 1991 by a team of researchers in Montreal. Dr. Jeanne D. Talbot of the University of Montreal and Dr. Catherine Bushnell of McGill University used PET scanning, which, like f.M.R.I., measures blood flow, to watch pain centers of the brain as they processed messages transmitted by nerve cells at the site of the injury.

When heat was applied at different intensities to the arms of eight right-handed male subjects, the researchers found, four different groups of pain cells ''lit up'' at different intensities.

In PET scanning, a radioactive tracer is injected into the subject before the scan is taken. When the tracer reaches the brain, detectors in the scanning machine are able to pick up positrons -- positive antiparticles of electrons -- emitted by the substance. The detectors determine where the positrons are located, and computers translate the data into three-dimensional pictures.

Since the discoveries in Montreal, imaging technology has steadily improved. Using these new techniques, neurologists, physicists and physiologists have in effect been given a tour of pain, as it registers in 200 or more regions of the cerebral cortex.

One of the most immediate uses of the new technology may be helping identify patients who are are unwilling or afraid to ask for help.

In a report last month in the Journal of the American Medical Association, for example, Dr. Kathleen Foley, a pain -control specialist at the Sloan-Kettering Cancer Center in Manhattan, reported on the case of ''Mrs. L.,'' a 44-year-old cancer patient she had treated. Mrs. L., Dr. Foley wrote, understated the amount of pain she was in because she wanted to remain lucid.

''I haven't really opened my mouth to say I was in pain,'' Dr. Foley quoted the patient as saying, ''and the trade-off has been a total fiasco.''

Mrs L. added: ''In my stupidity of wanting to stay awake, I say that I'm not in pain, and I find out later that makes it so much more difficult. I want to be awake and know everything that's going on, for as long as humanly possible. But I do not want to die in pain . I do not want to be in pain.''

More common, pain experts say, are patients who could not hide their pain if they wanted to. Dr. Apkarian said the first patients he studied were suffering from severe hand pain , in each case caused by some kind of accident. In these patients, he said, pain recurred long after the wound had healed, and the patients' hands were often so red and swollen that the nails began to drop off.

There is certainly no doubt that Mr. Kingsley is in pain. Approaching the huge, doughnut-shaped M.R.I. machine during a recent examination at University Hospital, he moved very slowly, his suffering obvious.

Mr. Kingsley said he is in pain about 70 percent of the day, every day. When he was 19, one vertebra in the small of his back started to slip down on another. Doctors told him he had better stop lifting heavy things and consider changing jobs.

''But I didn't listen,'' he said. ''The lesson from me is that if somebody tells you not to lift things, don't lift things.''

Four years ago, when the pain became unbearable, Mr. Kingsley finally quit his job. Two operations to insert pins in his back, readjusting the position of the vertebrae, did not help. And heavy doses of painkillers brought little relief.

Mr. Kingsley's doctors said they are at a loss to know why he suffers so much. Many other people with the same or similar conditions do not approach his level of pain, they said. They suggested that he might want to join the first group of patients being studied at the Syracuse center.

Inside the laboratory, the M.R.I. machine is sending radio waves into Mr. Kingsley's brain, while he lies positioned within the machine's strong magnetic field. The waves interact with the nuclei of hydrogen atoms in the cerebral cortex, in places where the pain is registered. The nuclei, in turn, emit their own, smaller radio signals, detected by the antenna in Mr. Kingsley's headrest, and translated into images that change slightly as his pain worsens or lessens.

Sean Huckins, a doctoral student in brain mapping, instructs Mr. Kingsley to use a set of hand signals to indicate to the team, watching from the glassed-in control room, the level of pain he is feeling as the technician raises his legs. After each trial, he is allowed to rest for a few minutes.

When Mr. Kingsley signals 9 1/2 the trial is halted. It will take weeks to analyze the data from his trial, Dr. Apkarian said, but the patterns generated by his brain seem, in preliminary analysis, to resemble those of the five other back- pain patients he has examined. They differ markedly, though, from those of six patients with chronic hand pain and two patients with spinal disorders.

''We've never had brain pictures of chronic pain before,'' Dr. Apkarian said, ''and they show that pain from different types of causes involved very different areas of the brain. And this seems to mean they should be treated differently. Just how will have to be subjected to much more investigation.''

After the session, Mr. Kingsley, clearly exhausted, says, ''It hurt like hell. But I'm at the point where I'm willing to try anything.''

''I've run out of options,'' he continues. ''So why not?''

The doctors have told him that whatever they learn from the research for which he has volunteered is unlikely to be of help to him or to others at least for several years.

''But all the patients who are willing and able to undergo this very difficult ordeal say that if it makes it possible for other people not to have to go through what they have gone through, it is worth it,'' Dr. Apkarian said.

Mr. Kingsley falters only once, when he describes his past life, and how he finally had to quit construction work when he could no longer stand the pain. Tears come to his eyes. ''I can't even get off the couch now to play with my grandchild,'' he says.