The response of hippocampal functional connectivity to sustained pain in a pain-sensitive population

Abstract

Objective The purpose of this study was to explore the effects of pain on functions and the relationship between functional changes in the hippocampus and attention and anxiety in a pain-sensitive population. Methods Fifty-three healthy subjects with no chronic pain were recruited in this study and divided into a pain-sensitive group (PS, n = 26) and a pain-tolerant group (PT, n = 27) according to the cold pressor test (CPT). Functional magnetic resonance imaging (fMRI) with a cold bottle test (cold and control conditions) was performed. The static and dynamic functional connectivity (FC) of the hippocampus was analyzed in both groups for the two conditions. Results Compared with PT, there were fewer static functional connections between the right hippocampus and the bilateral dorsolateral superior frontal gyrus in the PS group. Moreover, reduced functional connections between the hippocampus and brain regions were related to anxiety in the PS group, including the inferior temporal gyrus and the middle temporal gyrus. Significance Our results found that pain disturbed the default mode network in the PS group, which may be related to self-awareness. This result may reflect that people who are sensitive to pain are more likely to feel anxious.Key Points The functional connectivity within the DMN in the pain-sensitive group was significantly reduced, indicating the relationship between self-awareness and pain. The functional connectivity in the pain-sensitive group was significantly reduced in the hippocampus and some brain regions associated with anxiety, possibly reflecting the effect of pain on anxiety.

Keywords

• pain
• functional connectivity
• hippocampus
• pain sensitive