Neural Mechanisms of Personality and Decision Making
Psychologists are increasingly focused on identifying the biological substrates of personality traits. One promising method for identifying brain systems associated with personality traits is magnetic resonance imaging (MRI). Functional MRI is used to identify personality traits that are associated with brain processes during specific tasks. However, structural MRI can also be used and has the advantage that hypotheses about many personality traits can be examined simultaneously, because associations of traits with brain structure are not dependent on any specific task. In a previous test of the hypothesis that personality traits would be associated with the volume of specific brain structures, these researchers found support for a model specifying brain systems underlying each of the Big Five personality traits (Extraversion, Neuroticism, Agreeableness, Conscientiousness, and Openness/Intellect). However, this study did not differentiate between volume in gray matter versus white matter, an important anatomical distinction in the brain. Nor did it examine more specific personality traits based on subdivisions of the Big Five, which describe personality at a less general level of resolution and would allow testing of more specific biological hypotheses. The current project uses more finely differentiated measurements of personality traits in conjunction with a more sophisticated assessment of brain structure that parcellates gray and white matter and provides an index of gray matter thickness throughout the cortex. Cortical thickness has been shown to have important correlates, from learning of motor tasks to psychopathology. Assessing cortical thickness from MRI data is a computationally intensive process that can be accomplished using the MRI analysis program FreeSurfer. As this program typically takes up to 48 hours to process data for a single subject, and as this project examines associations of cortical thickness with personality in 300 subjects, the resources of MSI are invaluable. The researchers are also doing a more sophisticated DTI analysis for up to 200 individuals.
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