Functional neuroanatomy of lexical access in contextually and visually guided spoken word production

This collection is linked to Roos, Takashima, Piai. Functional neuroanatomy of lexical access in contextually and visually guided spoken word production. Cortex.
Abstract: Lexical access is commonly studied using bare picture naming, which is visually guided, but in real-life conversation, lexical access is more commonly contextually guided. In this study, we examined the underlying functional neuroanatomy of contextually and visually guided lexical access, and its consistency across sessions. We employed a context-driven picture naming task with fifteen healthy speakers reading sentences (word-by-word) and subsequently naming the picture depicting the final word. Sentences provided either a constrained or unconstrained lead-in setting for the picture to be named, thereby approximating lexical access in natural language use. The picture name could be planned either through sentence context (constrained) or picture appearance (unconstrained). This procedure was repeated in an equivalent second session two to four weeks later with the same sample to test for test-retest consistency. Picture naming times showed a strong context effect, confirming that constrained sentences speed up production of the final word. fMRI results showed that the areas common to contextually and visually guided lexical access were left fusiform, inferior frontal (both consistently active across-sessions), and middle temporal gyri. However, non-overlapping patterns were also found, notably in left temporal and parietal cortices, suggesting a different neural circuit for contextually versus visually guided lexical access.