Papers of the Week

Recent neuroimaging studies implicate the medial temporal lobe (MTL) in nociception and pain modulation. Here, we aim to identify which subregions of the MTL are involved in human pain and to test its connectivity in a cohort of chronic low back pain patients (CBP). We conducted two coordinate-based meta-analyses to determine which regions within the MTL showed consistent spatial patterns of functional activation (1) in response to experimental pain in healthy participants, and (2) in chronic pain compared to healthy participants. We followed PRISMA guidelines and performed activation likelihood estimate (ALE) meta-analyses. The first meta-analysis revealed consistent activation in the right anterior hippocampus (right antHC), parahippocampal gyrus and amygdala. The second meta-analysis revealed consistently less activation in patients' right antHC, compared to healthy participants. We then conducted a seed-to-voxel resting state functional connectivity of the right antHC seed with the rest of the brain in 77 CBP and 79 age-matched healthy participants. We found that CBP had significantly weaker antHC functional connectivity to the medial prefrontal cortex (mPFC) compared to healthy participants. Taken together, these data indicate that the antHC has abnormally lower activity in chronic pain, and reduced connectivity to the mPFC in CBP. Future studies should investigate the specific role of the antHC in the development and management of chronic pain.