Investigation of white matter functional networks underlying different behavioral profiles in attention-deficit/hyperactivity disorder

Background Cortical functional network alterations have been widely accepted as the neural basis of attention-deficit/hyperactivity disorder(ADHD).Recently,white matter has also been recognized as a novel neuroimaging marker of psychopathology and has been used as a complement to cortical functional networks to investigate brain–behavior relationships.However,disorder-specific features of white matter functional networks(WMFNs)are less well understood than those of gray matter functional networks.In the current study,we constructed WMFNs using a new strategy to characterize behavior-related network features in ADHD.Methods We recruited 46 drug-nale boys with ADHD and 46 typically developing(TD)boys,and used clustering analysis on restingstate functional magnetic resonance imaging data to generate WMFNs in each group.Intrinsic activity within each network was extracted,and the associations between network activity and behavior measures were assessed using correlation analysis.Results Nine WMFNs were identified for both ADHD and TD participants.However,boys with ADHD showed a splitting of the inferior corticospinal–cerebellar network and lacked a cognitive control network.In addition,boys with ADHD showed increased activity in the dorsal attention network and somatomotor network,which correlated positively with attention problems and hyperactivity symptom scores,respectively,while they presented decreased activity in the frontoparietal network and frontostriatal network in association with poorer performance in response inhibition,working memory,and verbal fluency.Conclusions We discovered a dual pattern of white matter network activity in drug-nale ADHD boys,with hyperactive symptom-related networks and hypoactive cognitive networks.These findings characterize two distinct types of WMFN in ADHD psychopathology.

Chemical composition and source apportionment of PM10 and PM2.5 in different functional areas of Lanzhou,China

To elucidate the air pollution characteristics of northern China, airborne PM_10（atmospheric dynamic equivalent diameter ≤ 10 μm） and PM_（2.5）（atmospheric dynamic equivalent diameter ≤ 2.5 μm） were sampled in three different functional areas（Yuzhong County,Xigu District and Chengguan District） of Lanzhou, and their chemical composition（elements, ions, carbonaceous species） was analyzed. The results demonstrated that the highest seasonal mean concentrations of PM_10（369.48 μg/m^3） and PM_（2.5）（295.42 μg/m^3） were detected in Xigu District in the winter, the lowest concentration of PM_（2.5）（53.15 μg/m^3） was observed in Yuzhong District in the fall and PM_10（89.60 μg/m^3） in Xigu District in the fall.The overall average OC/EC（organic carbon/elemental carbon） value was close to the representative OC/EC ratio for coal consumption, implying that the pollution of Lanzhou could be attributed to the burning of coal. The content of SNA（the sum of sulfate, nitrate,ammonium, SNA） in PM_（2.5）in Yuzhong County was generally lower than that at other sites in all seasons. The content of SNA in PM_（2.5）and PM_10 in Yuzhong County was generally lower than that at other sites in all seasons（0.24–0.38）, indicating that the conversion ratios from precursors to secondary aerosols in the low concentration area was slower than in the area with high and intense pollutants. Six primary particulate matter sources were chosen based on positive matrix factorization（PMF） analysis, and emissions from dust, secondary aerosols, and coal burning were identified to be the primary sources responsible for the particle pollution in Lanzhou.