Emotion, Personality, and the Frontal Lobe

Abstract

(from the chapter) Previous neuropsychological and functional neuroimaging studies on human emotion and personality have revealed the involvement of the frontal lobe. This chapter presents two original studies, a neuroimaging and a neuropsychological study, focusing on the neural mechanisms for emotional processing and personality. The first study concentrates on the neural substrates of advanced emotion. Over the past decade, many studies have primarily focused on basic emotions. In social situations, however, understanding more advanced complex emotions is also important for maintaining successful communications with others. To date, most of the neuroimaging studies on advanced emotions have focused on the neural substrates of recognizing those emotions, such as "theory-of-mind" reasoning. To determine the neural and cognitive mechanisms of advanced emotions, it is essential to focus on the neural substrates of advanced emotion learning, which remain poorly understood. The goal of the first study was to address this question using functional magnetic resonance imaging. The following important findings were obtained in the time-course data of activated brain areas: (I) the medial prefrontal (BA8) and the anterior cingulate cortex (BA32) were strongly activated in negative-based emotion learning, and (2) the right dorsolateral prefrontal cortex (BA9/46) was strongly activated in positive- and negative-based emotion learning. These results suggest that the prefrontal area is important for acquiring the relationship between social situations and complex facial expressions, and that these areas make independent contributions to learning specific emotions. The second study focuses on the function of the medial prefrontal cortex. Previous functional neuroimaging studies on "theory of mind" have demonstrated that the medial prefrontal cortex is involved when subjects are engaged in various kinds of mentalizing tasks. Although a large number of neuroimaging studies have been published, a somewhat small amount of neuropsychological evidence supports involvement of the medial prefrontal cortex in theory-of-mind reasoning. Findings are presented from a neuropsychological study for two neurological patients with damage to the medial prefrontal cortex. The results indicated that neither patient showed impairment on standard theory-of-mind tests and only mild impairments were seen on advanced theory-of-mind tests. The most striking finding was that both patients showed personality changes after surgical operations, leading to characteristics of autism and showing a lack of social interaction in everyday life. Finally, the possible roles of the medial prefrontal cortex are discussed, with emphasis on the importance of using multiple approaches to understand the mechanisms of theory of mind and medial prefrontal functions. (PsycINFO Database Record (c) 2014 APA, all rights reserved)