Previous research and theory suggest that two stable personality dimensions, extroversion and neuroticism, differentially influence emotional reactivity to a variety of pleasurable phenomena. Here, we use event-related functional MRI to address the putative neural and behavioral associations between humor appreciation and the personality dimensions of introversion-extroversion and emotional stability-neuroticism. Our analysis showed extroversion to positively correlate with humor-driven blood oxygenation leveldependent signal in discrete regions of the right orbital frontal cortex, ventrolateral prefrontal cortex, and bilateral temporal cortices. Introversion correlated with increased activation in several regions, most prominently the bilateral amygdala. Although neuroticism did not positively correlate with any whole-brain activation, emotional stability (i.e., the inverse of neuroticism) correlated with increased activation in the mesocortical-mesolimbic reward circuitry encompassing the right orbital frontal cortex, caudate, and nucleus accumbens. Our findings tie together existing neurobiological studies of humor appreciation and are compatible with the notion that personality style plays a fundamental role in the neurobiological systems subserving humor appreciation.S ince Eysenck and Jung (1-3) described their pioneering and highly influential views of personality, it has been widely acknowledged that laughter and merriment are common characteristics of the extroverted individual. Both empirical and anecdotal observations point to extroverts as having a higher frequency of laughter, smiling, feelings of subjective well-being, and an increased propensity to tell jokes (4, 5). The opposite is thought to be true of neurotics, who are epitomized by decreased feelings of subjective well-being, expressive laughter, smiling, and increased negative emotionality (4,(6)(7)(8). Although these stable individual differences in personality are posited to be deeply rooted in the brain's functional (9-11) and structural architecture (12), little is known of how they are associated with the underlying neurobiological systems responsible for the emotive and hedonic regulation associated with humor appreciation.Historically, a considerable body of clinicopathological literature, most famously Harlow's (13-16) lucid depiction of Phineas Gage, point to the prefrontal cortex (PFC) as a pivotal player in the maintenance of personality. With the recent emergence of functional MRI (fMRI), coupled with well validated measures of personality (17), the neuroscience community has witnessed a rekindled interest in the neural systems mediated by personality (11). For example, two recent fMRI studies by Canli and colleagues (9, 10) showed that extroversion positively correlates with phasic blood oxygenation level-dependent (BOLD) activity in the PFC and amygdala during the presentation of positively valanced faces, whereas neuroticism increases in association with middle temporal and frontal cortical activation during the presentation o...