Semantic Processing Of Chinese Two-character Words Under Visual And Auditory Pathway: A FMRI Study

Objectives:To explore and compare the brain activation of Chinese two-character words semantic processing under visual and auditory pathway with functional Magnetic Resonance Imaging(fMRI).Material and Methods:Subjects of this experiment are 12 healthy young volunteers,gender and age matched,right-handed,normal uncorrected or corrected visual acuity.Their all native language is Chinese.Experimental stimulus are graphic images of Chinese two-character words and simple figures(□ and ○),audio materials of same Chinese words and simple pure tone with equifrequent 1000Hz(sounds of dripping and tapping).60 Chinese words are selected from the frequency table of modern Chinese corpus.These two-character words are assigned into the same pair and different pair according to similar semantic or not,simple figures and pure tone are also divided into the same pair and different pair according to their actual content.All kinds above include 18 pairs each.During functional MRI scans,subjects are required to perform semantic judgment task of Chinese two-character words respectively under visual and auditory pathway.Subjects should also identify whether simple figures are same or not under visual pathway and identify simple pure tone under auditory pathway.The tasks are event-related designd.And in this experiment,the two factors mixed experimental design of 2 * 2.Collect the behavior experimental data and fMRI images of the semantic judgment under both visual and auditory pathway after scanning.SPSS was used to conduct statistical analysis of behavioral data,and Matlab based SPM8 software was used to analyze brain MRI images.The brain activation area of semantic judgment task are obtained and compared with each other under visual and auditory pathways,and the correlation between behavioral experiment and brain activation was analyzed.Results:According to the behavioral results of the subjects for Chinese two-character words semantic judgment under audio and visual pathways,the average response time and accuracy of the visual pathway group were 1568 ± 98 ms,96.0 ± 1.9% respectively,and 1342± 220 ms,95.1± 4.0% of auditory pathway group.The difference of response time of semantic judgment task between visual group and auditory was statistically significant(P < 0.05),while the average accuracy difference has no statistical significance(P > 0.05).Semantic processing related brain regions were activated when subjects make Chinese two-character words semantic judgment under both Visual and auditory pathways,visual pathway include: left middle temporal gyrus,inferior temporal gyrus(BA20/21),left occipital lobe(BA17/18);auditory pathway activated brain areas larger,mainly include: the right temporal and occipital lobe(BA37/19),left midle temporal gyrus,inferior temporal gyrus(BA20/21),bilateral occipital lobe and left parietal lobe(BA18).The left middle temporal gyrus and inferior temporal gyrus(BA20/21)were activated in both two groups of tasks.Conclusion:1.There is no significant difference in the semantic judgment accuracy of the two channels,which shows that the input path has no significant effect on the correctness of semantic processing.2.Some common areas of the brain were activated by both two pathways of visual and auditory,we suggest that the left middle and superior temporal gyrus(BA20/21)is a key brain area of semantic judgement.3.The results of this study demonstrate the existence of a semantic processing brain network,which includes the "core" brain regions that are coactivated,and the "peripheral" brain regions activated by different task requirements.