A new study by scientists at the University of Iowa, the California Institute of Technology and their colleagues sheds more light on how the amygdala works. The study, published in the Jan. 6 issue of Nature, suggests that the mechanism by which the amygdala contributes to processing visual information about facial expressions is by actively directing a person's gaze to the eye region to seek out and fixate on the critical visual cues for fear.
"People often think of the brain as passively receiving information from the senses about the world. This study shows that there are mechanisms in the brain that allow us to actively seek out information in the environment in the first place," said Ralph Adolphs, Ph.D., UI adjunct professor of neurology and professor of psychology and neuroscience at the California Institute of Technology.
The study extends the group's decade-long investigation involving patients who are essentially unable to recognize fearful expressions because of a damaged amygdala. The current series of experiments showed that a particular patient fails to make use of information about the eyes in faces, and one reason for that is that she fails to look at the eyes in faces in the first place.
The researchers found that they could restore the patient's ability to distinguish fear in facial expressions to normal levels by specifically instructing her to look at the eye region. However, this instruction had to be given each time the patient viewed a face otherwise she resumed her abnormal gaze pattern, did not fixate on the eyes and was not able to discern fear.
The findings suggest that the amy
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Contact: Jennifer Brown
jennifer-l-brown@uiowa.edu
319-335-9917
University of Iowa
5-Jan-2005