As part of my job reporting on neuroscience, I found myself in an unusual situation 10 years ago. During an interview, I offhandedly told a researcher to contact me if he ever needed a volunteer for a study. Months later the neurologist actually called, and I enrolled in a project on Parkinson's disease.

I was soon lying in a positron-emission tomography machine. Scientists injected a radioactive dye into my left arm, which felt warm and tingly as it coursed toward my brain. It settled in the regions that produce dopamine, a chemical that becomes depleted in Parkinson's. The researchers hoped that brain scans of middle-aged people could reveal the earliest signs of dopamine loss.

My dopamine levels turned out to be very high, "the highest we've seen in a normal volunteer," the neurologist told me. But he and his colleagues had also found something unsuspected. They wanted me to undergo magnetic resonance imaging (MRI) to highlight one particular area. Alarmed, I agreed, and a few days later they took the MRI scan. There, in a dark corner of my cerebellum, was a large ghostly-white mass. It wasn't pretty. The researcher, who was not a physician, shrugged uncomfortably. The radiologist said nothing. Many hours later the neurologist called and told me the shadow indicated a cyst and not to worry. I had probably had it since I was born.

What "IF" Scenarios
No one volunteers for a study expecting that something sinister may appear. But now, after more than a decade of brain-imaging research, scientists have run across the likes of me often, and they have finally pulled together to discuss the issue of such "incidental findings"--IF, for short. The findings range from tumors and blood clots to cysts and other structural abnormalities. Investigators simply don't know what to do when they happen on these anomalies in what are supposed to be "normal" test subjects.

This past January dozens of scientists, lawyers, ethicists and policymakers convened at the National Institutes of Health to debate the issue. It seems that incidental findings show up in 20 percent of subjects in research studies--a huge number--and there are still no official procedures for handling such discoveries. Judy Illes, a senior research scholar at the Stanford Center for Biomedical Ethics who organized the meeting, notes that researchers typically are not medical doctors and shouldn't be put in the position of practicing medicine. Yet they become good at sizing up scans. What should they do when they spot something? When should they scan and tell?

The answer is not easy, Illes and other experts note. Scans are like Rorschach tests: in the best hands, scans can still be interpreted differently. No one even agrees what a normal brain should look like.

"It's a judgment call," says David Eidelberg, director of neuroscience at the North Shore Long Island Jewish Health System in Manhasset, N.Y. "There are lots of variants of normal. Do you tell a person that they have a cyst in their brain that will never alter the course of their life? I'm not sure."

This position, in essence, is that there is no reason to alarm a test subject unnecessarily. But others say volunteers should be told about any kind of unusual indications, whether it might worry them or not. It's their brain, and they should be informed about it. The sticking point is that scientists have no uniform way of handling incidental findings. Illes and her colleagues want to adopt a basic framework to follow. "The idea is to come up with solutions to protect our research volunteers, our patients and our institutions," Illes says.

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