Verbal Memory and Sentence Processing in the Inferior Frontal Lobe Private

Abstract:
Using blood flow change, we investigated the function of the left inferior frontal lobe in sentence processing. 12 subjects (10F; 2M; mean age 21.54) read sentences and responded when they recognized words from a memory set. The effects of lexical memory load (maintaining 1 vs 5 words) and of sentence complexity (reading 1 vs. 2 clause sentences) showed up as an anti-additive interaction in the left frontal operculum and underlying anterior insula. The interaction between these two factors suggests that a single neural network in the frontal operculum supports both lexical verbal memory and syntactic processing or working memory, since two separate but spatially contiguous networks should lead to additive effects. A main effect of memory load was found in the left cuneus, which may support a visually coded memory system. There was also a tendency toward an interaction between sentence complexity and memory load in the left parietal cortex; the form of the interaction was the inverse of the pattern seen in frontal cortex; this inversion may indicate a strategic re-allocation of working memory resources to the verbatim memory task depending on the availability of frontal working memory resources.