Seeking the source of emotions.
In studying the roots of emotion, researchers typically focus on facial expressions for clues to the different emotions babies experience. These expressions apparently reflect a "central emotional system" in the brain that formulates positive and negative emotions during the first year of life, says psychologist Nathan A. Fox of the University of Maryland in College Park.
Fox, who spoke at the recent annual meeting of the American Psychological Association in New Orleans, contends the "primary" emotions--joy, interest, fear, disgust, anger and sadness--emerge under the direction of an inner-brain structure called the amygdala.
Recent animal studies conducted by psychologist Joseph E. LeDoux of Cornell University Medical College in New York City indicate the amygdala determines the emotional importance of stimuli. In human infants, Fox maintains, the amygdala may evaluate sensory information and handle the decision to approach or withdraw from an object, person or situation. Complex emotions are probably forged as the amygdala gradually develops neuronal connections to the brain's frontal lobes, he adds.
One signal of a baby's tendency to approach or withdraw from an emotional stimulus is the pattern of electrical activity across the surface of the brain, Fox asserts. Over the past seven years, he and his co-workers have found that electrical activity in an infant's left brain hemisphere surges during positive emotions, while electrical activity in the right hemisphere greatly increases during negative emotions. They obtain measurements via electrodes embedded in a metal cap placed over an infant's head.
Right hemisphere activation is most striking when a baby cries, Fox notes, whereas activity intensifies in the left hemisphere during a smile.
Much remains unknown about the roles of the right and left hemispheres in emotional development (SN: 3/11/89, p.149). Nevertheless, changes in the electrical charges produced by the hemispheres appear to mirror infants' emotional experiences in different situations, Fox says.
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|Date:||Sep 9, 1989|
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