Similarity And Association:Principles Of Distributed Semantic Processing In The Human Brain

Human's lexical semantic processing is a biophysical process that recruits neuronetworks and neural activation dynamics.It is possible to measure the neural activities via neuroimaging techniques.The semantic processing connects the various forms of linguistic expression such as speeches and texts to the cognition-internal concept comprehensions and meanings.Centering the lexical semantic processing in the human brain,this paper argues for a possible dissociation of two distinct sub-processes that contribute from two different semantic aspects: semantic similarity and association.The proposition of the two aspects are based on the theoretical linguistic structurelism of paradigmatic and syntagmatic axes in semantics,as well as on the pathological studies of linguistic impairements.We apply the theory of mental representation and neuroimaging techniques,combined with computational semantic representational embedding models to investigate the plausibility of a semantic hub-and-spoke model that implements the two sub-processes.This study proposes the construction of similarity and association semantic embeddings respectively by transforming Word Net-alike knowledge bases and subtracting paradigmatic information from a statistical word embedding.It evaluates the semantic embeddings by leveraging word-pair proximity ranking tasks.The neural structures responsible for similarity and association processing are revealed in an f MRI encoding experiment in auditory semantic processing tasks.We leverage the voxel-encoding models' performance contrasts,trained with the two types of semantic features,to reveal the brain's spatial pattern for semantic processing.Results indicate that in listening comprehension,similarity and association semantic operations both recruit inferior(ITG)and middle temporal gyri(MTG),angular gyrus,superior parietal lobule(SPL),inferior frontal gyrus.The ITG,middle occipital gyrus and the surrounding primary and associative visual areas are more engaged by association processing.The comparison of two semantic axes' brain map does not suggest a neuroanatomical segregation for similarity and association processing.The complex yet regular contrast pattern starting from temporal pole,along MTG to SPL necessitates further investigation.