Investigating the role of memory on pain perception using FMRI

Thesis

It is now widely accepted that the experience of pain is subject to cognitive influences that may determine the severity of subjectively perceived pain. Many of these top-down factors rely on memory-based processes, which in turn are related to prior experience, learned beliefs and behaviours about pain. As such, memory for pain heavily contributes to the physical pain experience. We posit that pain memory is bidirectional in that following each painful event a trace is stored and that these traces in turn may modify future pain perception prospectively. The following body of work explores aspects of what we have termed a memory template for pain. The results of these chapters taken together, examine these bidirectional aspects of short-term memory for pain employing a recall pain task. Specifically, we explore how, after an acute pain event, a short-term mental representation of the initial event persists. We show that during this time, sensory re-experiencing of the painful event is possible. Furthermore, we investigate aspects of recalled pain, namely intensity and vividness. Data suggests that the intensity and the vividness of this mental representation are determined by the intensity of the initial stimulus, as well as the time-to-test delay. We identify regions that characterise short-term memory for pain. Following on from studies in motor and visual imagery, we explore how pain imagery in the form of recall may affect subsequent pain perception. Our results demonstrate that the inclusion of pain-related imagery preceding physical pain events reduces affective qualities of pain. Testing healthy, naïve subjects, we replicate the effect observed in studies using attention management and imagery strategies, which normally require extensive training. Finally, in a cohort of neuropathic pain patients we show significant reductions in white matter connectivity between areas responsible for working and prospective memory. Collectively, these studies emphasise and elucidate the role of short-term memory of pain in physical pain perception. Acting both retrospectively and prospectively, cognitive reinforcement can increase or decrease the subjective feeling of pain, and therefore manipulating how pain is recalled may have therapeutic potential.

Authors: Fairhurst, K

• Publication date: 2011
• DOI: 10.5287/ora-gwy5gk7jm
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: pain; primary sensory cortex; FMRI; perception; imagined pain; short-term memory
• Subjects: Neuroscience; Cognitive therapy; Anaesthetics; Medical Sciences; Cognitive Neuroscience