Bartolo, A., Benuzzi, F., Nocetti, L., Baraldi, P., & Nichelli, P. (2006). Humor Comprehension and Appreciation: An fMRI Study. J. Cogn. Neurosci., 18(11), 1789-1798.

Humor is a unique ability in human beings. Suls proposed a two-stage model of humor: detection and resolution of incongruity. Incongruity is generated when a prediction is not confirmed in the final part of a story. To comprehend humor, it is necessary to revisit the story, transforming an incongruous situation into a funny, congruous one. Patient and neuroimaging studies carried out until now lead to different outcomes. In particular, patient studies found that right brain-lesion patients have difficulties in humor comprehension, whereas neuroimaging studies suggested a major involvement of the left hemisphere in both humor detection and comprehension. To prevent activation of the left hemisphere due to language processing, we devised a nonverbal task comprising cartoon pairs. Our findings demonstrate activation of both the left and the right hemispheres when comparing funny versus nonfunny cartoons. In particular, we found activation of the right inferior frontal gyrus (BA 47), the left superior temporal gyrus (BA 38), the left middle temporal gyrus (BA 21), and the left cerebellum. These areas were also activated in a nonverbal task exploring attribution of intention. We hypothesize that the resolution of incongruity might occur through a process of intention attribution. We also asked subjects to rate the funniness of each cartoon pair. A parametric analysis showed that the left amygdala was activated in relation to subjective amusement. We hypothesize that the amygdala plays a key role in giving humor an emotional dimension.

Goel, V., & Dolan, R. J. (2001). The functional anatomy of humor: segregating cognitive and affective components. Nature Neuroscience, 4(3), 237-238.

Humor, a unique human characteristic, is critical in thought, communication and social interaction. Successful jokes involve a cognitive juxtaposition of mental sets, followed by an affective feeling of amusement; we isolated these two components of humor by using event-related fMRI on subjects who listened to auditorily present-ed semantic and phonological jokes (puns) and indicated whether or not they found the items amusing. Our findings suggest that where-as there are modality-specific pathways for processing the juxtaposition of mental sets necessary for the appreciation of jokes, a common component of humor is expressed in activity in medial ventral prefrontal cortex, a region involved in reward processing.(Aka medial orbitofrontal cortex)
a related paper on a different author's web page

Azim, E., Mobbs, D., Jo, B., Menon, V., & Reiss, A. L. (2005). Sex differences in brain activation elicited by humor. PNAS, 102(45), 16496-16501.

With recent investigation beginning to reveal the cortical and subcortical neuroanatomical correlates of humor appreciation, the present event-related functional MRI (fMRI) study was designed to elucidate sex-specific recruitment of these humor related networks. Twenty healthy subjects (10 females) underwent fMRI scanning while subjectively rating 70 verbal and nonverbal achromatic cartoons as funny or unfunny. Data were analyzed by comparing blood oxygenation-level-dependent signal activation during funny and unfunny stimuli. Males and females share an extensive humor-response strategy as indicated by recruitment of similar brain regions: both activate the temporal-occipital junction and temporal pole, structures implicated in semantic knowledge and juxtaposition, and the inferior frontal gyrus, likely to be involved in language processing. Females, however, activate the left prefrontal cortex more than males, suggesting a greater degree of executive processing and language-based decoding. Females also exhibit greater activation of mesolimbic regions, including the nucleus accumbens, implying greater reward network response and possibly less reward expectation. These results indicate sex-specific differences in neural response to humor with implications for sex-based disparities in the integration of cognition and emotion.