Resting-state connectivity in the default mode network and insula during experimental low back pain

Functional magnetic resonance imaging studies have shown that the insular cortex has a signif- icant role in pain identification and information integration, while the default mode network is associated with cognitive and memory-related aspects of pain perception. However, changes in the functional connectivity between the defauk mode network and insula during pain remain unclear. This study used 3.0 T functional magnetic resonance imaging scans in 12 healthy sub- jects aged 24.8 ± 3.3 years to compare the differences in the functional activity and connectivity of the insula and default mode network between the baseline and pain condition induced by intramuscular injection of hypertonic saline. Compared with the baseline, the insula was more functionally connected with the medial prefrontal and lateral temporal cortices, whereas there was lower connectivity with the posterior cingulate cortex, precuneus and inferior parietal lobule in the pain condition. In addition, compared with baseline, the anterior cingulate cortex exhibited greater connectivity with the posterior insula, but lower connectivity with the anterior insula, during the pain condition. These data indicate that experimental low back pain led to dysfunction in the connectivity between the insula and default mode network resulting from an impairment of the regions of the brain related to cognition and emotion, suggesting the impor- tance of the interaction between these regions in pain processing.

Effect of dexamethasone on intelligence and hearing in preterm infants: a meta-analysis

OBJECTIVE： A meta-analysis of published randomized controlled trials investigating the long- term effect of dexamethasone on the nervous system of preterm infants. DATA SOURCES： Online literature retrieval was conducted using The Cochrane Library （from January 1993 to June 2013）, EMBASE （from January 1980 to June 2013）, MEDLINE （from Janu- ary 1963 to June 2013）, OVID （from January 1993 to June 2013）, Springer （from January 1994 to June 2013） and Chinese Academic Journal Full-text Database （from January 1994 to June 2013）. Key words were preterm infants and dexamethasone in English and Chinese. STUDY SELECTION： Selected studies were randomized controlled trials assessing the effect of intravenous dexamethasone in preterm infants. The quality of the included papers was evaluated and those without the development of the nervous system and animal experiments were exclud- ed. Quality assessment was performed through bias risk evaluation in accordance with Cochrane Handbook 5.1.0 software in the Cochrane Collaboration. The homogeneous studies were analyzed and compared using Revman 5.2.6 software, and then effect model was selected and analyzed. Those papers failed to be included in the meta-analysis were subjected to descriptive analysis. MAIN OUTCOME MEASURES： Nervous system injury in preterm infants. RESULTS： Ten randomized controlled trials were screened, involving 1,038 subjects. Among them 512 cases received dexamethasone treatment while 526 cases served as placebo control group and blank control group. Meta-analysis results showed that the incidence of cerebral palsy, visual im- pairment and hearing loss in preterm infants after dexamethasone treatment within 7 days after birth was similar to that in the control group （RR = 1.47, 95%CI： 0.97-2.21; RR = 1.46, 95%CI： 0.97-2.20; RR = 0.80, 95%CI： 0.54-1.18; P 〉 0.05）, but intelligence quotient was significantly de- creased compared with the control group （MD = -3.55, 95%CI： -6.59 to -0.51; P = 0.02）. Prete rm infants treated with dexamethasone 7 days after birth demonstrated an incidence of cerebral palsy and visual impairment, and changes in intelligence quotient similar to those in the control group （RR = 1.26, 95%CI： 0.89-1.79; RR = 1.37, 95%CI： 0.73-2.59; RR = 0.53, 95%CI： 0.32-0.89; RR = 1.66, 95%CI： -4.7 to 8.01; P 〉 0.05）. However, the incidence of hearing loss was significantly increased compared with that in the control group （RR = 0.53, 95%CI： 0.32-0.89; P = 0.02）. CONCLUSION： Dexamethasone may affect the intelligence of preterm infants in the early stages after birth, but may lead to hearing impairment at later stages after birth. More reliable conclusions should be made through large-size, multi-center, well-designed randomized controlled trials.