Semantic and syntactic information processing during auditory language comprehension: A spectral stereo-EEG approach

There is no consensus regarding clear-cut brain functional dissociations of semantic and syntactic information processing networks. Recent studies proposed a functional dissociation at the spectral level in which semantic and syntactic processes were associated with neural network activity at different frequency intervals. This study aimed at investigating this functional dissociation for semantic and syntactic information during auditory language comprehension. For this purpose, we collaborated with 11 drug-resistant epilepsy patients undergoing deep electrode implantation brain recordings. Patients were instructed to listen to four different types of auditory stimuli (in which semantic and syntactic information were manipulated): sentences, jabberwockys, word lists, and pseudoword lists. Results showed no clear dissociation between semantic and syntactic processing in the left language canonical network. In the temporo-parietal regions two distinct subnetworks, each with its own spectral signature, were observed. Semantic information processing appeared to elicit stronger high frequency activity in the temporal pole, while syntactic information processing elicited low frequency activity increases in the middle temporal as well as the supramarginal gyri. Interestingly, a specific spectral functional dissociation in the pars triangularis was observed suggesting that a single region could support both functional processes within distinct neural frequency intervals.