Functional MRI Investigation of the Neural Basis of Human Pain Processing in the Brainstem and Spinal Cord; Descending Regulation and Chronic Pain

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Ioachim, Gabriela
fMRI , Neuroimaging , Human , Pain , Chronic , Brainstem , Spinal cord , Expectation , Fibromyalgia , Provoked vestibulodynia
Pain is a complex experience that includes sensory components, descending pain modulation, and cognitive and emotional effects. A combination of any or all of these effects may be altered in chronic pain conditions. The objective of this thesis was to investigate how network connectivity is altered during the expectation and experience of pain in previously established brainstem and spinal cord pain regulation and resting-state networks, and then compare this to data from groups with fibromyalgia (FM) and provoked vestibulodynia (PVD). FM and PVD are two chronic pain conditions disproportionately affecting women, the underlying mechanisms of which are still poorly understood. The thesis consisted of three main projects. The first study in healthy volunteers compared previously observed resting state fluctuations in the brainstem and spinal cord to connectivity changes observed during the expectation of a predictable noxious stimulus and showed that some of the observed variations seem to be specific to the expectation of pain. Building on this data, the next study then compared a group of women with fibromyalgia with a group of healthy individuals during the expectation and experience of a noxious stimulus in order to better understand the neural processes underlying heightened pain sensitivity in FM. These results showed that pain processing is altered in the brainstem/spinal cord in FM during the expectation and experience of pain in specific ways. The differences in pain processing in FM suggest that the altered pain processing in this condition may be linked to a combination of changes in pain modulation and autonomic regulation networks. The last study then compared a group of women with FM and a group of women with PVD with a group of healthy individuals in order to explore how pain processing is altered at the level of the brainstem/spinal cord in chronic pain as well as what elements of pain modulation during the expectation and experience of pain are unique to each chronic pain condition. These results revealed important differences between potential underlying mechanisms of FM and PVD and help to characterize how brainstem/spinal cord networks are altered in chronic pain.
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