Brain Response Determined More by Personality Type Than by Thought

February 05, 2001

New York (MedscapeWire) Feb 5 — How our brains respond to different environmental stimuli is in large measure a result of personality type, according to a new study that examines brain activity by magnetic resonance imaging (MRI). This study, published by the American Psychological Association in the February issue of Behavioral Neuroscience , suggests that depending on whether a person is extraverted or neurotic, his or her brain will amplify different experiences over others.

Turhan Canli, PhD, a psychologist from Stanford University, and colleagues used functional magnetic resonance imaging (fMRI) to measure the relation between brain responses to emotional stimuli — pictures. While in a fMRI scanner, 14 healthy 19- to 42-year-old women's brain reactions to pictures containing negative images (crying or angry people, spiders, guns, or a cemetery) or positive images (happy couple, puppies, foods like ice cream or brownies, or sunsets) that provoked strong emotional reactions were determined. A personality measure was also used to help the researchers determine the participants' level of extraversion — the tendency to be optimistic and sociable — and their level of neuroticism — the tendency to be anxious, worried, and socially insecure.

The fMRI results show that the women who scored high on extraversion also had greater brain reactivity to positive stimuli compared with negative stimuli than did those women who scored low on extraversion. The associations between extraversion and neural activity in response to positive images were observable in several areas of the brain that control emotion, including the frontal cortex, amygdala, and anterior cingulate.

For the women who scored low on extraversion, no brain reactivity to positive stimuli was found. But those who scored high on the neuroticism measures had more brain reactions to negative stimuli, but in fewer parts of the brain that control emotions.

"Depending on personality traits, people's brains seem to amplify some aspects of experience over others," said John D. E. Gabrieli, PhD, one of the study's coauthors. "All of the participants saw very positive and very negative scenes, but people's reactions were very different. One group saw the cup as being very full while the other group saw it as very empty."

These results show that individual differences in brain reactivity to emotional stimuli are associated with specific personality traits, which also supports earlier MRI studies of extraverted and depressed people, according to the authors. Extraverts were found to have elevated frontal blood flow even at rest compared with introverts, and depressed patients whose conditions have been linked to neuroticism were found to have reduced blood flow in that same region of the brain.

Previous examinations of emotion and brain activation have had inconsistent results, said Dr. Canli. Some studies have shown that the amygdala, a part of the brain responsible for emotional memory, plays a role in shaping emotional experience, face recognition, and processing visual and emotional stimuli. Other research contradicts those findings and maybe, Canli says, because the participants in the studies were more extraverted than those in other studies. "Those personality differences could lead to differing amygdala responses across studies."

In future studies, said Dr. Canli, we will assign participants more specific tasks to perform while viewing emotional stimuli, such as rating the emotional experience they are having, retrieving emotional memories, or encoding the pictures into memory. "By doing that, we begin to lay out a road map of how personality plays into our emotional processing in specific domains of functioning, such as attention, experience, memory and perception."

Behav Neurosci. 2001;115(1):000-000