Brain Mechanism Of Language Cognitive Process-Based On TMS And FMRI Technology

Language is a special high-level function of human beings.Language research is one of the important ways to explore human nature.Therefore,the study of language cognitive mechanism has been one of the important issues in many fields.Language cognition includes many cognitive processes,such as language comprehension and language production.This study mainly focuses on the neural mechanisms of language cognitive processing.Using functional Magnetic Resonance Imaging(fMRI)and non-invasive Transcranial Magnetic Stimulation(TMS),a series of studies have been conducted on the characteristics of language cognitive processes,especially semantic cognitive processing and language production,and their neural information mechanisms.The main work is divided into the following four parts:1.Based on functional magnetic resonance(fmri)research on language comprehension tasks,exploring the brain network mechanism of semantic cognitive processing.The semantic processing network mainly involves left inferior frontal gyrus(such as Broca’s region),left middle temporal gyrus,bilateral parietal sulcus,occipital lobe,cerebellum and other important brain functional areas.At the same time,functional connection analysis showed that the left inferior frontal gyrus had significantly enhanced connection with the left middle temporal gyrus when the left inferior frontal gyrus was the seed point.Moreover,the connection strength of the left inferior frontal gyrus and middle temporal gyrus was negatively correlated with the behavior.That is,the stronger the connection between the left inferior frontal gyrus and the middle temporal gyrus,the better the behavior of the subjects.The results showed that the left inferior frontal gyrus and the left middle temporal gyrus played a synergistic role in semantic cognitive processing.In addition,this study did not find the right-brain laterality and chinese-specific regions of semantic processing.The neural basis of semantic cognitive processing in Chinese is very similar to that in English and other phonetic languages,that is,semantic processing is realized through the division of labor and cooperation among brain regions in the semantic network,which supports the hypothesis of linguistic commonality of semantic processing.2.Exploring from the spatial dimension which brain regions in semantic cognitive processing network are the key brain regions involved in semantic cognitive processing.The previous work found that the left inferior frontal gyrus(IFG)and the left middle temporal gyrus(MTG)were significantly activated in semantic processing,while the right intraparietal sulcus(IPS)was significantly activated in the numerical judgment task compared with the semantic judgment task.To this end,the study applied IFG-TMS,MTG-TMS and IPS-TMS to the subjects in the semantic and numerical processing stage in real time to carry out reversible virtual damage to these three brain regions.The results showed that compared with the vertex stimulation of the control site,TMS intervention on the left side of IFG significantly reduced the behavior performance of semantic task,while intervention on the left side of MTG did not reduce the behavior performance of semantic task.Our results have shown that the left inferior frontal gyrus not only participates in Chinese semantic cognitive processing,but also plays a key role in it.However,although the left temporal middle gyrus cooperates with the left inferior frontal gyrus in semantic cognitive processing,it does not play a key role.In addition,TMS intervention in the right parietal sulcus IPS significantly reduced the behavioral performance of numerical tasks,suggesting that the right parietal sulcus IPS is a key brain region for number processing.3.Based on the existing brain network foundation of semantic cognitive processing,exploring the reorganization and compensation of semantic cognitive processing network after virtual injury in the left inferior frontal gyrus.The previous work found that semantic cognitive processing network is mainly composed of left frontal lobe,left temporal lobe,parietal lobe,occipital lobe and cerebellum,among which the left inferior frontal gyrus plays a key role in semantic cognitive processing.However,studies on aphasia and stroke patients have shown that when the left frontal lobe is damaged,the functional network connections of various brain regions in semantic cognitive processing may be changed,which plays a functional compensation role to the lateral brain regions.To this end,this study took normal subjects and used offline TMS and fMRI technology to explore the changes in the activity of each brain region in the semantic cognitive processing network when the left inferior frontal gyrus was virtual impaired.The results showed that when the left inferior frontal gyrus was damaged,the activation degree of the left middle temporal gyrus decreased significantly.Meanwhile,cortical activity in the right insula was significantly increased.Moreover,functional connections between the right insula and the left inferior frontal gyrus were significantly correlated with behavioral performance after TMS stimulation.The results showed that when the left inferior frontal gyrus was damaged,the right brain region was involved in the reorganization and compensation of semantic cognitive processing.4.Exploring the role of the left inferior frontal gyrus in language production from the time dimension.Studies have shown that the left inferior frontal gyrus is not only a key brain region for semantic cognitive processing,but also involved in the process of language production.Therefore,this study focused on the neural mechanism of language generation,took ideographic Chinese as the research object,adopted the traditional picture naming paradigm,and stimulated the Broca area of the left inferior frontal gyrus with real and sham TMS at five different moments.The results showed that compared with the sham stimulus,the Broca area of TMS stimulation significantly reduced the behavior from 225 ms to 400 ms after the picture onset.The results confirmed that the Broca region of the left inferior frontal gyrus was involved in language production,especially in syllable coding.At the same time,the syllabification process in the production of Chinese speech is about 225 ms to 400 ms,a little earlier than the phonetic alphabet(about 300 ms).The reason for this difference may be that two different language systems have different syllabification mechanisms.To sum up,this paper reveals from the spatial dimension that semantic cognitive processing invokes a neural network with extensive distribution of frontal,temporal and parietal lobes.This network takes the left inferior frontal gyrus as the core region,and other brain regions cooperate with each other.When the core area is damaged,the network is reorganized and compensated through the right side of the brain.However,the research on the neural mechanism of language generation indicates that there are indeed linguistic differences at some linguistic levels.Therefore,the research on the cognitive mechanism of Chinese language not only reflects the universality of the cognitive neural mechanism of different orthographies but also reveals the differences of language.