Papers of the Week

Human and animal imaging studies demonstrated that chronic pain profoundly alters the structure and the functionality of several brain regions and even causes mental dysfunctions such as depression and anxiety disorders. In this article, we conducted a multimodal study cross-sectionally and longitudinally, to evaluate how neuropathic pain affects the brain. Using the spared nerve injury (SNI) model which promotes long-lasting mechanical allodynia, results showed that neuropathic pain deeply modified the intrinsic organization of the brain functional network 2 weeks after injury. There are significant changes in the activity of the left Thalamus (Th_L) and left Olfactory Bulb (OB_L) brain regions after SNI, as evidenced by both the blood-oxygen-level-dependent (BOLD) signal and c-Fos expression. Importantly, these changes were closely related to mechanical pain behavior of rats. However, it is worth noting that after morphine administration for analgesia, only the increased activity in the TH region is reversed, while the decreased activity in the OB region becomes more prominent. Functional connectivity and c-Fos correlation analysis further showed these two regions of interest (ROI) exhibit different functional connectivity patterns with other brain regions. Our study comprehensively revealed the adaptive changes of brain neural networks induced by nerve injury in both cross-sectional and longitudinal dimensions and emphasized the abnormal activity and functional connectivity of Th_L and OB_L in the pathological condition. It provides reliable assistance in exploring the intricate mechanisms of diseases. Neuropathic pain is a debilitating condition caused by lesion or disease of the somatosensory nervous system. In the present study, we applied a non-invasive neuroimaging technique, functional magnetic resonance imaging (fMRI) to elucidate the underlying mechanisms. We showed the significant changes in brain activity and functional network connectivity in rats following nerve injury through the simultaneous implementation of both cross-sectional and longitudinal research. The thalamus and olfactory bulb were further identified as the key functional brain regions that might be involved in SNI-induced mechanical hypersensitivity, which provides reliable ideas and directions for further exploring the brain network and neural circuit mechanisms of neuropathic pain.