**3. Prefrontal deficit, impairment in pragmatic ability, theory of mind, and executive function**

Injuries in the prefrontal and other regions are shown to causally involve in the impaired communicative-pragmatic ability. Traumatic brain injuries are typically characterized by the damage to the frontal lobes, resulting in deficits in executive functions, and the ability to manage goal-directed behavior. ToM difficulties were able to predict poor performance in speech production task. Moreover, the impact of ToM on one's communicative performance was more pronounced when the task involved stronger inhibition, for example, when participants were asked to initially think about a specific event from their own perspective, inhibit that perspective and switch to someone else's perspective. Individuals with the traumatic brain injury (TBI) suffer from a general difficulty in managing social communication in everyday life, for example, they display poor ability to negotiate efficient request [31] or at giving right amount of information to the interlocutor [32], conversational problems including turn taking [33], and narrative disorders [34]. In a study on the communicative ability in TBI individuals [35], 30 patients with traumatic brain injury and 30 healthy individuals were tested on executive function, theory of mind, and communicative-pragmatic functions using the Assessment Battery of Communication (ABaCo). Among all TBI patients, 25 suffered from focal damage in the frontal regions (among whom 15 were lesioned in the right frontal, 6 in the left frontal, and 6 in bilateral frontal or frontal-diffuse areas). The TBP participants were poor in the comprehension and production tasks in the ABaCo, on both linguistic and extralinguistic measures, as well as in the EF (higher-level executive control tasks including the working memory, planning, and cognitive flexibility) and ToM tasks (including the first- and secondorder theory of mind, or mentalizing the other person's mind or the another's knowledge toward others), the latter of which predict individual's performance in the communicativepragmatic tasks.

reading of emotion-laden literature. Reading fictions involves language-related processes including constructive content imagination and simulation [46], perspective taking and relational inferences [47]. These processes were represented by the extended language network associated with discourse comprehension, the neural mechanisms underlying high-level/ multimodal semantic integration [44, 48], and theory of mind network, generally including vmPFC, dmPFC, IFG, aTL, TPJ, PCC, precuneus, and left amygdala. The effects of emotionality were demonstrated to predict the left amygdala, vmPFC, and the pons when listening to emotion-laden text passages [40]. Ref. [49] showed that the happy passage activated left precentral gyrus (the head/face area on the somatotopy) and bilateral amygdala when the literature was presented in reader's first language (L1 reading, German) only; while regardless of the language status, the emotion-laden literature activated emotion-related amygdala and lateral prefrontal, anterior temporal, and temporo-parietal regions associated with the discourse comprehension, high-level semantic integration, and ToM processing. Moreover, the multivariate pattern analysis approach revealed better accuracy of differential patterns of brain activity in predicting different emotional contents in L1 than second language (L2), with the sensitivity attenuated in the L2 relative to the L1. These patterns showed the neural activations that support provide stronger and more differentiated emotional experience in

Prefrontal Cortex: Role in Language Communication during Social Interaction

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reading our native than the second language texts.

**5. Transmitting and learning language in social contexts**

How are messages propagated? What are the underlying neural mechanisms? One key aspect regarding how our language is grounded into the social interaction is the synchronized linguistic behavior between communicative partners. The tendency to become more similar in the use of nonverbal cues (e.g., [50]), linguistic structures (e.g., [51]), and neural activity associated with producing and decoding narratives (e.g., [52, 53]). Are the mechanisms of verbal synchrony or linguistic style matching between communicators applied to the relationship between the use of social language by one communicator and that by the listener who subsequently retransmit the message? One fMRI study addressed the neural mechanisms underlying the processing and retransmission of social language in the context of word-ofmouth sharing [54]. The brain systems that are engaged in considering the mental states of others are particularly engaged by social features of language (e.g., words associated with social interaction, which referred to individuals who maybe participate in a social interaction, such as "friend", or those used to describe these interactive processes, such as "exchange"), and the activity within the brain's mentalizing system during exposure to ideas predicts the subsequent extent to which social language is employed in describing the ideas to others. In particular, the brain mentalizing system included the bilateral TPJ, dorsomedial prefrontal cortex (dmPFC) as well as the precuneus and PCC [55]. Previous literature has examined the mechanisms of successful communication in pairs [52, 53] and how simulation of other's mental states can facilitate effective idea retransmission [56, 57]. They showed that the use of more social words to introduce ideas was associated with increased neural activation in the dmPFC, bilateral TPJ, and temporal pole in the participants, the networks that were typically
