The probes in Dave Kewley's hands were damaged --easy to do with such delicate instruments -- thus Kewley has no qualms holding them. Operational probes, however, are so sensitive that during the manufacturing process they can only be handled with tweezers by gloved researchers in sterile "clean" rooms. "Even a fleck of dust will occlude some chemical reactions," says Kewley, a lanky, graduate student with a thick mop of blond hair and blue eyes that really twinkle.
Kewley's tiny monitoring devices, science's newest data collection tools, are part of an technical armamentarium neuroscientists have been creating for years. PET scans, which measure glucose metabolis, can take snapshots of the brain in action. Magnetic Resonance Imaging (MRI) photographs the structure of the brain. The newest technique, functional magnetic resonance imaging (fMRI) can make "movies" of the brain as it "thinks," remembers and even dreams. Even updated versions of the "old" EEG are still used. These techniques are not invasive and take pictures of large areas of the brain. But the subjects studied must remain stationary, and groups of cells are invisible in the blur of large-scale activity.
Neuroscientists have also developed painstakingly delicate techniques for measuring electrical activity of individual cells or even single channels within a cell by means of tiny "patch clamps" that monitor the flow of ions in and out of cell bodies. Using electrodes, they have learned to listen to one neuron at a time.
"But up until now, there have been no conventional techniques for studying more than just a few neurons in the living brain," explains Kewley, "no sensor that you can leave outside in the brain and watch in real time what lots of individual neurons are doing two millimeters down. With these sensors we might be able to record from hundreds or thousands of single cells at the same time." Moreover, unlike conventional electrodes, the new technology enables the researchers to determine the precise position of the probes in relation to each other as the measurements proceed.
-- Linda Marsa
