Mindfulness training cultivates momentary awareness, a form of attention directed to non-evaluative, immediate sensation. This form of attention stands in contrast to a more temporally extended awareness, which allows for the evaluative organization of experience into a personal narrative. The neural mechanisms underlying such awareness, and their role in regulating emotions, are poorly understood. Thus, in three functional magnetic resonance imaging (fMRI) experiments, I explored the thesis that momentary and extended awareness represent dissociable modes of self-reference, with momentary self-reference reducing ruminative elaboration of events by biasing attention towards interoceptive signals from the body. I compared individuals who were randomly-assigned to either an 8-week Mindfulness-Based Stress Reduction (MBSR) training course against a waitlisted group (Controls). Three distinct studies examined the impact of Mindfulness on: 1) the contrast between explicitly directed momentary and extended self referential processing; 2) reactions to an induced sadness challenge; and 3) the contrast between interoceptive (breath-monitoring) and exteroceptive (visual) attention. In all three studies MBSR led to a shift in neural activity away from cortical midline structures, such as the medial prefrontal and posterior cingulate cortices, to predominantly right-lateralized viscerosomatic structures, and specifically the insular cortex. Cortical midline activity is thought to support habitual patterns of evaluation, and stands as the neural correlate of a narrated, extended self, while right-lateralized insula activity is thought to represent the recurrent integration of present moment context, the neural correlate of the momentary self. These data revealed that MBSR may enhance the distinction between momentary and extended self-reference, reducing cortical midline responses and recruiting a novel, right-lateralized viscerosomatic network. Additionally, MBSR graduates demonstrated reduced emotional reactivity to a film-based sadness mood induction, reducing cortical midline activity and inhibition of the right insula. Moreover, the MBSR group demonstrated enhanced right middle insula recruitment during the monitoring of sensory experience associated with breath monitoring, a core mindfulness practice. The data from this final study also suggest that MBSR promoted an integration of posterior insular sensory representations with anterior insular subjective representations of present moment status. Preserved viscerosomatic activity in the face of emotional challenge may be a predictor of enhanced well-being following mindfulness training.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/35754 |
| Date | 26 July 2013 |
| Creators | Farb, Norman A. S. |
| Contributors | Anderson, Adam K. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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