Perceived communicative intent in gesture and language modulates the superior temporal sulcus.

Behavioral evidence and theory suggest gesture and language processing may be part of a shared cognitive system for communication. While much research demonstrates both gesture and language recruit regions along perisylvian cortex, relatively less work has tested functional segregation within these regions on an individual level. Additionally, while most work has focused on a shared semantic network, less has examined shared regions for processing communicative intent. To address these questions, functional and structural MRI data were collected from 24 adult participants while viewing videos of an experimenter producing communicative, Participant-Directed Gestures (PDG) (e.g., "Hello, come here"), noncommunicative Self-adaptor Gestures (SG) (e.g., smoothing hair), and three written text conditions: (1) Participant-Directed Sentences (PDS), matched in content to PDG, (2) Third-person Sentences (3PS), describing a character's actions from a third-person perspective, and (3) meaningless sentences, Jabberwocky (JW). Surface-based conjunction and individual functional region of interest analyses identified shared neural activation between gesture (PDGvsSG) and language processing using two different language contrasts. Conjunction analyses of gesture (PDGvsSG) and Third-person Sentences versus Jabberwocky revealed overlap within left anterior and posterior superior temporal sulcus (STS). Conjunction analyses of gesture and Participant-Directed Sentences to Third-person Sentences revealed regions sensitive to communicative intent, including the left middle and posterior STS and left inferior frontal gyrus. Further, parametric modulation using participants' ratings of stimuli revealed sensitivity of left posterior STS to individual perceptions of communicative intent in gesture. These data highlight an important role of the STS in processing participant-directed communicative intent through gesture and language. Hum Brain Mapp 37:3444-3461, 2016.