Near infrared spectroscopy(NIRS)is generally accepted as a functional brain imaging technology for brain activation study.With multichannel highly sensitive NIRS instruments,it has become possible to assess functional...Near infrared spectroscopy(NIRS)is generally accepted as a functional brain imaging technology for brain activation study.With multichannel highly sensitive NIRS instruments,it has become possible to assess functional connectivity of different brain negions by NIRS.However,the feasibility needs to be validated in complex cognitive activities.In this study,we recorded the hemodynamic activity of the bilateral prefrontal cortex(PFC)during a color-word matching Stroop task.Wavelet transform coberence(WTC)analysis was applied to ascss the functional conectivity of all homologous channel pairs within the left/right PFC.Both the behavioral and brain activ ation results showed signifcant Stroop effects.The results of WTC analysis revealed that,bilateral functional connectivity was significantly stronger during both the incongruent stimuli and neutral stimuli compared to that of the rest period.It also showed significant Stroop effect.Our findings demonstrate that,NIRS bcomes a valuable tool to elucidate the functional conectivity of brain cortex in complex cognitive activities.展开更多
The recent hiatus in global warming has attracted significant attention,yet whether it is a widespread global and/or regional phenomenon remains controversial.Here,we investigate the response of extreme temperature ch...The recent hiatus in global warming has attracted significant attention,yet whether it is a widespread global and/or regional phenomenon remains controversial.Here,we investigate the response of extreme temperature changes since 1961 across China's cold regions(CCR):Tibetan determine the spatiotemporal characteristics of extreme temperature changes across these cold regions using Mann-Kendall and wavelet transform coherence(WTC)analyses of data from 196 meteorological stations from 1961 to 2018.We further investigate the teleconnection between extreme temperatures and large-scale ocean-atmosphere circulation to determine the potential synoptic scale causes of the observed changes.The results revealed a significant warming slowdown in all extreme tempera-ture indices across CCR from 1998 to 2018.In addition,extreme temperature indices in northwest cold region(NWC)and north cold region(NC)reveal a clear winter warming slowdown and even a significant cooling trend,yet only the cold index in Tibetan Platean cold region(TPC)shows a warming hiatus.We conclude that the warming hiatus observed across these regions is primarily driven by extreme temperature index changes in winter.We also find that phase variations in the Atlantic Multi-decadal Oscillation(AMO)and Arctic Oscillation(AO)critically impact on the observed warming hiatus,but the specific atmospheric mechanisms are elusive and warrant further analysis and investigation.展开更多
基金supported by the Science Fund for Creative Research Group of China(Grant No.61121004)National Natural Science Foundation of China(Grant No.61078072)863 Program(Grant No.2012AA02A602).
文摘Near infrared spectroscopy(NIRS)is generally accepted as a functional brain imaging technology for brain activation study.With multichannel highly sensitive NIRS instruments,it has become possible to assess functional connectivity of different brain negions by NIRS.However,the feasibility needs to be validated in complex cognitive activities.In this study,we recorded the hemodynamic activity of the bilateral prefrontal cortex(PFC)during a color-word matching Stroop task.Wavelet transform coberence(WTC)analysis was applied to ascss the functional conectivity of all homologous channel pairs within the left/right PFC.Both the behavioral and brain activ ation results showed signifcant Stroop effects.The results of WTC analysis revealed that,bilateral functional connectivity was significantly stronger during both the incongruent stimuli and neutral stimuli compared to that of the rest period.It also showed significant Stroop effect.Our findings demonstrate that,NIRS bcomes a valuable tool to elucidate the functional conectivity of brain cortex in complex cognitive activities.
文摘The recent hiatus in global warming has attracted significant attention,yet whether it is a widespread global and/or regional phenomenon remains controversial.Here,we investigate the response of extreme temperature changes since 1961 across China's cold regions(CCR):Tibetan determine the spatiotemporal characteristics of extreme temperature changes across these cold regions using Mann-Kendall and wavelet transform coherence(WTC)analyses of data from 196 meteorological stations from 1961 to 2018.We further investigate the teleconnection between extreme temperatures and large-scale ocean-atmosphere circulation to determine the potential synoptic scale causes of the observed changes.The results revealed a significant warming slowdown in all extreme tempera-ture indices across CCR from 1998 to 2018.In addition,extreme temperature indices in northwest cold region(NWC)and north cold region(NC)reveal a clear winter warming slowdown and even a significant cooling trend,yet only the cold index in Tibetan Platean cold region(TPC)shows a warming hiatus.We conclude that the warming hiatus observed across these regions is primarily driven by extreme temperature index changes in winter.We also find that phase variations in the Atlantic Multi-decadal Oscillation(AMO)and Arctic Oscillation(AO)critically impact on the observed warming hiatus,but the specific atmospheric mechanisms are elusive and warrant further analysis and investigation.
