You may be asleep, but there's a place in the side of your brain that stays awake. It's listening for a baby's cry, a rattle in the lock or some other sign of trouble.
Research by a Johns Hopkins University undergraduate suggests that there is a spot in the front of the brain that also stays up, perhaps deciding which noises are serious enough to demand that you be awakened.
Hopkins junior Serena J. Gondek, 21, presented the findings yesterday in Minneapolis in a rare undergraduate talk before neurologists and neuroscience professionals at the annual meeting of the American Academy of Neurology.
"The reason we think it is also taking place in the frontal area is that that has been found to be the area where the executive and attention functions are found that perform motor planning, attention and possibly even arousal [from sleep]," Gondek said.
It's an area that likely would be involved if the brain were differentiating between a baby's cry, which would require arousal, and a dripping sink, which you could safely sleep through.
The next goals for her research, she said, may include tests with a variety of environmental sounds, to see whether the frontal area really is discriminating among the noises and deciding how to respond.
Without that kind of sound- and thought-processing while asleep, early man "would have been eaten," said Dr. Gregory L. Krauss, an assistant professor of neurology at Hopkins who directed Gondek's work. But surprisingly little is known about where in the brain it takes place, and how it actually works.
Scientists had assumed that the listening and filtering was done in the brain's primary auditory complex, in the side of the brain above the ear.
"To see a very large area of the frontal lobe very active when we present sounds in sleep was a surprise," Krauss said. "We actually do quite a lot of processing while we're asleep, monitoring our environment."
Gondek admitted that her 15-minute presentation yesterday had her a little nervous. But she has had some practice.
She recently gave the talk as a participant in Hopkins' Biomedical Engineering Undergraduate Research Awards program, which she won. And she gave it as a poster session presentation for the Neuroscience Honor Society, which she also won.
Krauss said an undergraduate talk before the neurology meeting is rare.
"I've seen residents who are beyond their medical school years do it, and I've seen senior medical school students do it. But I've never seen an undergraduate do it. It's probably notable," he said.
Gondek, a resident of Oakbrook, Ill., is considering a career in medicine or biomedical engineering. She chose to attend Hopkins in part because it provides opportunities for undergrads to do research with faculty members.
She began working with Krauss during her freshman year, helping with a study that revealed inaccuracies and misconceptions in news media articles about epilepsy.
The sleep study was suggested to her by Krauss, and supported by a General Electric Foundation Undergraduate Engineering Research Stipend. Gondek worked on the study full time last summer and for about 10 hours a week during the regular school year.
The experiments required the cooperation of five patients who were preparing to undergo brain surgery to curtail epileptic seizures. Electrodes implanted in their brains to measure and map seizure activity were also used to record responses to noises.
The patients wore soft earphones that blocked out room sounds but allowed them to hear two pure tones. Gondek played the tones while the patients were awake, during light sleep and during deep sleep.
"It was usually 2 or 3 in the morning before I went to bed," she said. The electrodes pinpointed the parts of the patients' brains that responded to the tones. Gondek superimposed the results on MRI and CT scans made of the patients' brains and analyzed the results.
Gondek said prior studies had involved electrodes glued to the scalp. "It revealed something was going on. But it could not be localized. Being directly over the cortex, we can say it was happening over the primary auditory cortex and the lateral frontal cortex."
After a summer working at a neurology center in Slovenia, Gondek will return to her sleep study next fall.
Pub Date: 4/29/98