Mapping chemical changes in brain.

• Position: Stroke research

Scientists have developed a new technique that maps chemical changes occurring in the brain as a result of stroke or head injuries. Although current research is done using animal models, they hope that such maps, when extended to humans, will help screen for drugs that can block or reverse these chemical reactions, thereby saving lives and reducing possible future disabilities.

The technique, near-infrared (near-IR) spectrometry, exceeds the capabilities of two techniques currently in use-magnetic resonance imaging (MRI) and X-rays - according to Robert A. Lodder of the College of Pharmacy at the University of Kentucky Medical Center.

Among other medical applications, the technique would benefit research on aging, help predict short-term memory problems associated with strokes, and could monitor oxygenation of hemoglobin (a protein that transports oxygen from the lungs to body tissues) in patients having difficulty breathing.

A light source, a sample box, and a spectrophotometer are the key components of the technique. The light - its frequency chosen in the near-IR region of the light spectrum - is used to probe the brain of a sedated gerbil as it sits in a sample box and receives a scientist-delivered stroke. The light partially is absorbed by the. animal while the rest is scattered. The map of chemical changes is hidden in the scattered light and is deciphered...