Modulation of the lexical-semantic network by auditory semantic priming: an event-related functional MRI study

The current event-related fMRI study specifies the neuroanatomical correlates of semantic priming and differences in semantic relation types using an auditory primed lexical decision task (LDT). Word pairs consisted of different relation types, associations (key-chain), pure categorical relations (cow-dog), and unrelated words (table-window), as well as word-pseudoword (way-tinne) and pseudoword-pseudoword (ahurn-döva) pairs. The factor lexical status, i.e., the processing of words compared to pseudowords, was associated with activation in the middle temporal gyri and the left striatum. The factor relatedness, i.e., the contrast between unrelated and related target words, was associated with increased activation of the left inferior frontal gyrus, the deep frontal operculum bilaterally, and the middle frontal gyri. A direct contrast between the two semantic relation types indicated that the processing of purely categorical compared to associative information recruits the right precuneus, the isthmus gyrus cinguli, and the cuneus, suggesting more effortful processing of the former information type. The present data show that the factors lexical status, semantic relatedness, and type of semantic relation in a primed LDT modulate the hemodynamic response in cerebral areas that subserve auditory word recognition and subsequent lexical-semantic processing.