Studies on functional and structural changes in the primary somatosensory cortex (S1) have provided important insights into neural mechanisms underlying several chronic pain conditions. However, the role of S1 plasticity in postherpetic neuralgia (PHN) remains elusive. Combining psychophysics and magnetic resonance imaging (MRI), we investigated whether pain in PHN patients is linked to S1 reorganization as compared with healthy controls. Results from voxel-based morphometry showed no structural differences between groups. To characterize functional plasticity, we compared S1 responses to noxious laser stimuli of a fixed intensity between both groups and assessed the relationship between S1 activation and spontaneous pain in PHN patients. Although the intensity of evoked pain was comparable in both groups, PHN patients exhibited greater activation in S1 ipsilateral to the stimulated hand. Painrelated activity was identified in contralateral superior S1 (SS1) in controls as expected, but in bilateral inferior S1 (IS1) in PHN patients with no overlap between SS1 and IS1. Contralateral SS1 engaged during evoked pain in controls encoded spontaneous pain in patients, suggesting functional S1 reorganization in PHN.Resting-state fMRI data showed decreased functional connectivity between left and right SS1 in PHN patients, which scaled with the intensity of spontaneous pain.Finally, multivariate pattern analyses (MVPA) demonstrated that BOLD activity and resting-state functional connectivity of S1 predicted within-subject variations of evoked and spontaneous pain intensities across groups. In summary, functional reorganization in S1 might play a key role in chronic pain related to PHN and could be a potential treatment target in this patient group.
Numerous neuroimaging studies have demonstrated that the brain plasticity is associated with chronic low back pain (cLBP). However, there is a lack of knowledge regarding the underlying mechanisms of thalamic pathways for chronic pain and psychological effects in cLBP caused by lumbar disc herniation (LDH). Combining psychophysics and magnetic resonance imaging (MRI), we investigated the structural and functional brain plasticity in 36 patients with LDH compared with 38 age- and gender-matched healthy controls. We found that (1) LDH patients had increased psychophysical disturbs (i.e., depression and anxiety), and depression (Beck-Depression Inventory, BDI) was found to be an outstanding significant factor to predict chronic pain (short form of the McGill Pain Questionnaire, SF-MPQ); (2) the LDH group showed significantly smaller fractional anisotropy values in the region of posterior corona radiate while gray matter volumes were comparable in both groups; (3) resting state functional connectivity analysis revealed that LDH patients exhibited increased temporal coupling between the thalamus and dorsolateral prefrontal cortex (DLPFC), which further mediate the relationship from chronic pain to depression. Our results emphasized that thalamic pathways underlying prefrontal cortex might play a key role in regulating chronic pain and depression of the pathophysiology of LDH.
In recent years, functional magnetic resonance imaging (fMRI) has been widely used in studies that explored the personality-brain association. Researches on personality neuroscience have the potential to provide personality psychology with explanatory models—that is, why people differ from each other rather than how they differ from each other (DeYoung and Gray, 2009). As one of the most important dimensions of personality traits, extraversion is the most stable core and a universal component in personality theory. The aim of the present study was to employ a fully data-driven approach to study the brain mechanism of extraversion in a sample of 111 healthy adults. The Eysenck Personality Questionnaire (EPQ) was used to measure the personality characteristics of all the subjects. We investigated whether the subjects can be grouped into highly homogeneous communities according to the characteristics of their intrinsic connectivity networks (ICNs). The resultant subjects communities and the representative characteristics of ICNs were then associated to personality concepts. Finally, we found one ICN (salience network) whose subject community profiles exhibited significant associations with Extraversion trait.
Music shows tremendous promise in pain relief, especially when considering its nonpharmacological nature. However, our understanding of the precise mechanisms behind music-induced analgesia (MIA) remains poor. The positive emotional state induced by music is one of the key components explaining MIA. To test this possibility and reveal its neural correlates, the present study applied nociceptive laser stimuli to 28 healthy participants when their liked or disliked songs were played as background music, or when they were resting in silence. Differences among conditions were quantified by self-reports of pain intensity and unpleasantness, as well as brain activations in response to acute laser stimuli. As expected, liked music significantly lowered pain ratings to acute painful stimuli compared to disliked music and no music. Consistent with this observation, brain activations in response to acute painful stimuli were deceased within brain areas encoding sensory components of pain, such as the right precentral and postcentral gyri (PreCG/PoCG), brain areas related to affective components of pain, such as the anterior cingulate cortex and bilateral putamen, and brain areas associated with motor control and avoidance reactions to pain, such as the left cerebellum, when liked music was played in the background in comparison to disliked music. Importantly, the relationship between music listening and differences in pain ratings of two music conditions was mediated by the magnitude of right PreCG/PoCG and left cerebellum activations. These findings deepened our understanding of the analgesic benefits of background liked music, a property relevant to clinical applications.
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