The neural basis of joy and sadness: A functional magnetic resonance imaging study of the neuro-affective effects of music, laughter and crying

Compared to the number of studies investigating emotional processing of various external stimuli, there is a dearth of fMRI studies investigating internally generated emotions. The aim of this project was to develop a new objective way to generate emotional/affective processes in the brain that could be used in brain imaging studies. The selected methodology, whereby the internal mental imagery of laughter and crying (to evoke joy and sadness), along with the affectively neutral task of imaging walking allowed evocation of affective states without the confounding effects of motor artifacts. This approach was used to help resolve where certain internal, subjectively experienced states are elaborated within the brain. As a contrast, emotions were also induced externally using personally meaningful musical selections.; Subjects' brains were imaged (using the fMRI BOLD procedure) during alternating 30-second blocks of rest and motor imagery for 4-minute sessions. Affective response scores (9-point Likert scale) indicated that internal laughter significantly increased happiness and decreased sadness. Conversely, crying imagery significantly increased sadness and decreased happiness. The brain areas exhibiting BOLD signal changes during these tasks are consistent with regions involved in affect generation and motor imagery. For example, crying and laughing imagery induced reciprocal changes in the right insula and inferior frontal gyrus, which are commonly aroused in emotion studies. Walk imagery, however, elicited changes in the right middle and superior frontal gyri, areas previously demonstrated to simply play a role in motor imagery. Alternating blocks of silence and happy or sad music were used as a robust external affect-inducer. Only happy music showed changes across-subjects in brain activity compared to silence. These changes occurred in music and emotional processing areas such as right superior temporal and left middle temporal gyri. These data suggest that emotional-motor imagery can induce significant changes in emotional state and brain activity in an fMRI study, and that internally and externally generated emotions have different patterns of activation. This work is discussed in the contest of modern emotion theory.