Representing linguistic communicative functions in the premotor cortex

Abstract

Linguistic communication is often regarded as an action that serves a function to convey the speaker's goal to the addressee. Here, with an functional magnetic resonance imaging (fMRI) study and a lesion study, we demonstrated that communicative functions are represented in the human premotor cortex. Participants read scripts involving 2 interlocutors. Each script contained a critical sentence said by the speaker with a communicative function of either making a Promise, a Request, or a Reply to the addressee's query. With various preceding contexts, the critical sentences were supposed to induce neural activities associated with communicative functions rather than specific actions literally described by these sentences. The fMRI results showed that the premotor cortex contained more information, as revealed by multivariate analyses, on communicative functions and relevant interlocutors' attitudes than the perisylvian language regions. The lesion study results showed that, relative to healthy controls, the understanding of communicative functions was impaired in patients with lesions in the premotor cortex, whereas no reliable difference was observed between the healthy controls and patients with lesions in other brain regions. These findings convergently suggest the crucial role of the premotor cortex in representing the functions of linguistic communications, supporting that linguistic communication can be seen as an action.

Causal role of frontocentral beta oscillation in comprehending linguistic communicative functions

“…Specifically, in comprehending linguistic communications, the comprehender likely mentally simulates the interlocutors' interaction involving their attitudes toward the communicated content. This was evidenced by the enhanced beta tACS effect on the predictability of communicative functions based on the speaker's will rating, and by the effect of premotor lesion on the speaker's will and addressee's will ratings in our previous study (Chang et al, 2022). To interpret the attitudes, the comprehender can take the perspective of the speaker, the initiator of the communication, and engage in a simulated situation and mentally build a model of the interactive situation between the interlocutors.…”

“…The same sets of scripts from our previous lesion study (Chang et al, 2022) were used in Experiments 1A and 1B. These scripts described daily-life communicative scenarios.…”

“…As several theories consider linguistic communication as a kind of actions, neuroimaging studies indeed observed the involvement of the neural substrates for motor action not only in speech production/perception engaging motor programing (Wilson et al, 2004) but also in comprehending linguistic communicative functions conveyed by specific contents (Chang et al, 2022;Egorova et al, 2016;van Ackeren et al, 2012). For example, in our recent functional magnetic resonance imaging (fMRI) study (Chang et al, 2022), we found that the distinct communicative functions, such as promising, requesting, and replying, can be discriminated by the multivariate activity patterns in the premotor cortex. Moreover, these multivariate activities also contained the information about the interlocutors' attitudes.…”

“…Thus, the speaker's utterance conveying distinct communicative functions in different situations also conveys their distinct attitude towards the current situation or task (Chang et al, 2022;Pérez Hernández, 2001).…”

“…While both commissive and directive involve the interlocutors’ attitude toward the task, assertive (e.g., replying to a query) is an objective description of a situation that can be irrelevant to the interlocutors’ attitude. Thus, the speaker’s utterance conveying distinct communicative functions in different situations also conveys their distinct attitude towards the current situation or task (Pérez Hernández, 2001; Chang et al, 2022).…”