Correlation between LIFG and Autonomic Activation during Stressful Tasks:A Functional Near-infrared Spectroscopy (fNIRS) Study

It remains unclear whether language tasks in one＇s first （L1） or second （L2） language can cause stress responses and whether frontal, autonomic and behavioral responses to stressful tasks are correlated. In this study, we studied 22 Chinese subjects whose L2 was English and measured the cerebral blood oxygenation in their frontal lobe by using functional near-infrared spectroscopy （fNIRS） as par- ticipants engaged in a mental arithmetic task （MAT） and verbal fluency tasks （VFTs） in L1 （Chinese） and L2 （English）. To examine the activated cortical areas, we estimated the channel location based on Montreal Neurological Institute （MNI） standard brain space by using a-probabilistic estimation method. We evaluated heart rate （HR） changes to analyze autonomic nervous system （ANS） functioning. We found that the MAT and VFTs induced greater increases in HR than did the control （Ctrl） task. Further- more, subjects developed greater increases in HR in the MAT and VFTt~ than they did in the VFTL1. Compared with the Ctrl task, the MAT and both VFTLland VFTL2 produced robust and widespread bi- lateral activation of the frontal cortex. Interestingly, partial correlation analysis indicated that the activity in the left inferior frontal gyrus （LIFG） [Brodmarm＇s area （BA） 47] was consistently correlated with the increases in HR across the three tasks （MAT, VFTL2, and VFTL1）, after controlling for the performance data. The present results suggested that a VFT in L2 may be more stressful than in L1. The LIFG may affect the activation of the sympathetic system induced by stressful tasks, includin~ MATs and VFTs.

Observation on effect of meridian stimulation on blood oxygenation level of brain by applying Near Infra Red Spectrum(NIRS)

Objective To observe the effect of stimulating Yinttang （印堂 EX-HN 3） and Baihui（百会 GV 20） with electroacupuncture （EA） on blood oxygenation level of brain and explore the feasibility of measuring the therapeutic effect of acupuncture by applying near infra red spectrum （NIRS）. Methods Ten participants semi-randomly selected from 158 adults （random test sequence） were stimulated with EA at the acupoints of EX-HN 3 and GV 20. Verbal fluency task was conducted before and after acupuncture, and changes in blood oxygenation level of cerebral cortex were tested by applying NIRS. Quantitative data were processed with JMP 10.0.2 software, and changes in waveforms of blood oxygenation level of brain before and after treatment were compared by applying NIRS. Results ① The mean of reacting dose （integral value） of blood oxygenation level of cerebral cortex of the 158 adults in the verbal fluency task was 10.6 ± 1.1, and the mean of the whole reacting dose of blood oxygenation level of cerebral cortex at 1/2 period of time during the test （centroids value） was 46.8 ± 1.6. ② In the EA group, the mean of integral value and centroids value of 10 adults were 8.4 ± 5.1 and 54.7± 12.2 before EA while 9.8±3.5 and 41.2±6.7 after EA. The integral value and centroids value of the EA group were closer to the mean of all the subjects. Conclusion It was found by NIRS that the blood oxygenation level of cerebral cortex could be regulated in bi- directional way by stimulating EX-HN 3 and GV 20 with EA, and a further research on whether it directly related to EA is to be made.