Answers to brain function

• Stuttering, which affects 1 million Americans, may be treated medically someday because its cause is being isolated. People stutter because of an abnormality in the speech motor circuits of the cerebrum and cerebellum. This discovery by Dr. Fox and co- investigators Roger J. Ingham, PhD, and Janis Costello Ingham, PhD, of the University of California at Santa Barbara, helps explain why stutterers speak smoothly when they read in unison with another person.

• The biological origin of depression, which affects an additional 15 million Americans, is being pinpointed in experiments by Helen S. Mayberg, MD, an associate professor of neurology and psychiatry. She also has begun unique research to unlock the mystery of human mood changes. Depression, Dr. Mayberg has found, is characterized by abnormal brain blood flow in the paralimbic frontal lobe. Her "mood challenge" experiments, which provoke emotional states in test subjects, show a relationship between clinical depression and the emotion of sadness. Dr. Mayberg's work gives one of the first profiles of how people process their emotions. Her findings also suggest new strategies for treating depressed patients.

• Brain surgery's risks may be reduced because of a test for patients that Dr. Fox helped develop and improve. Using high-tech imaging, physicians can more sharply define language centers of a patient's brain before surgery by giving what is called a "generate verbs" test. The patient responds to a noun such as "hammer" by saying an appropriate verb such as "pound." Clinical trials of the test are being conducted by researchers from Yale, Harvard and other universities. For both patient and neurosurgeon, the test offers a major advantage: It reduces the risk of accidentally harming parts of the brain that process speech.