**1. Introduction: indirect language and social inferential networks**

Language is uniquely human in that the communication via language is inherently social [1]. Unlike other cognitive systems such as visual perception which does not necessarily

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

involve the input from social interaction, the human acquisition of language-processing abilities heavily rely on the social input. One of the main functions of language is to establish, maintain, and modify social relations. The meanings that are conveyed by language are situated in social settings and are hence highly negotiable. Newly emergent research in cognitive neuroscience of language argues that the meaning at different linguistic levels depends on social interactions and ongoing representation of body actions [2]. This chapter therefore elucidates the neural representations underlying social language processing, summarizing the representative studies that showed the involvement of prefrontal regions during processing language that conveys social information or supported by social interaction. We highlight that multiple neurocognitive components underlying social functions in the prefrontal cortex have successfully guided humans to understand language in social contexts. We will extend our perspectives into (1) indirect language and social inferential networks, (2) recognizing speech/communicative acts and action-related networks, the relation between prefrontal deficits, pragmatic impairments, and the role of theory of mind (ToM) and executive functions; (3) neural correlates of reading emotion-laden literary; (4) transmission and learning of language in social contexts; and (5) cognitive empathy and pragmatic language processing.

what a speaker affirms and his private knowledge and requires the derivation of the shared knowledge between the speaker and the listener [10]. When the speaker produces the irony, they expect the listener to detect whereas the speaker does not expect the listener to recognize the deceit. One study explored the neural activations underlying the irony and deceitful statements [11]. Healthy individuals read statements used in sincere, deceitful, and ironic way (e.g., It's a beautiful day.). In both deceitful and ironic statements, the speaker implies the opposite of what he says [12, 13]. Compared with the since voice, both deceitful and ironic voices increased activations in the left fronto-temporal network, including the left IFG, dlPFC, and middle frontal gyrus (MFG). The IFG suggests that a demanded inferential process of the correct intended meaning from the (wrong) literal meaning of the utterance. The dlPFC suggests the involvement of executive functions to combine the inferences necessary to understand the speaker's intention to deceive with the comprehension that social norms are violated. The ironic statements uniquely activated the left MFG as compared with the deceitful statements. These findings highlight the role of prefrontal areas underlying both executive functions and social inference processes in the interpretation of pragmatic meanings from the statement.

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The ability to detect the literal meaning maybe disrupted in schizophrenia patients who showed difficulties in successfully decoding meaning of ironic conversational turns [14] and in perspective taking and second-order theory of mind processes that the irony comprehension heavily relies on [14, 15]. Lesion and functional magnetic resonance imaging (fMRI) evidence has found the involvement of medial prefrontal cortex in theory of mind processing [16], and the involvement of right lateral temporal lobe [17] or the left MTG/superior temporal gyrus (STG) or the left lateral prefrontal cortex (lPFC) [18] in detecting nonliteral meanings. One study demonstrated that, as compared with literal statements, reading ironic statements ending the text vignettes activated a bilateral network including the left medial prefrontal and left inferior parietal gyri [18]. The increased activation in the mPFC suggests the involvement of second-order "theory of mind" processing in the ironic and sarcastic stimuli. The increased activation in the bilateral middle temporal gyrus in reading ironic statements were negatively associated with the reader's schizophrenic trait score (measured by schizotypal personality questionnaire, SPQ), suggesting that the more activated the bilateral MTG, the lower SPQ score when the participant read the ironic statement. These findings suggest that individuals with schizotypical personality traits are associated with a dysfunctional lateral temporal language rather than a prefrontal theory of mind network; moreover, the processing of ironic language maybe interrupted by neural mechanisms underlying the functional impairment of schizotypical personality [19]. A positive correlation was found between the activation in the left IFG when participants read irony and the SPQ possibly suggesting an involvement of additional semantic integration processes when the nonliteral sentence was encountered. Indirect response is a "face-saving" strategy and serves as a tool for manipulating the addressee by a socially navigating individual. One study scanned the participants' brain when they listened to a reply from a job candidate that was either addressed to them (when they imagined themselves as the addressee) or to the interviewer in a job interview setting (when they overheard the conversations from the candidate and the interviewer [20]). They observed that the indirect reply, which functioned as a politeness strategy to mitigate the potential verbal threatening on the speaker's face (e.g., *I am planning to take a language course this summer*.

To detect that a conversational turn is intended to be ironic or sincere, the listener must go beyond the literal meaning. The medial prefrontal cortex (mPFC), together with the precuneus and bilateral temporal parietal junction (TPJ), forms the neuronal network for mentalizing that is correlated with the speaker meaning on the overhearers (e.g., [3–5]). These regions were more active when listeners heard the ironic utterances (*Tonight we gave a superb performance* said by an opera singer after a disastrous performance; [6]), and sentences with ambiguous references (*When Beyonce met Madonna she had just had a little accident at the hairdressers*) as compared with the literal or unambiguous control sentences. Some irony comprehension tasks also found the medial prefrontal cortex (mPFC) and middle temporal gyrus (MTG)/superior temporal sulcus (STS) [7]. The irony comprehension also involved areas related with the high executive demands and integrative processes, including the inferior frontal gyrus (IFG), MTG, and dorsolateral prefrontal cortex. Recognition of communication intention during language comprehension, in particular, the comprehension of a speech act, recruits extended neural networks. Uchiyama and colleagues found prominent activation in the IFG, MTG, and mPFC during recognizing ironic meaning [8]. The authors interpreted activation in the mPFC as being related with mentalizing activity, and activation in the IFG and MTG being related with activity in the semantic-executive system engaged in the semantic retrieval, selection, and evaluation during sentence comprehension. Harada et al. examined the neural correlates using the task where the participants judged whether the protagonist in a story uttered a speech act with the intention to deceive, or whether their behavior was morally acceptable [9]. The deceit recognition task activated the bilateral TPJ, inferior parietal lobule (IPL), the right MTG and dorsal lateral PFC (dlPFC), with the dlPFC activation related with the executive demands set by the task. Both tasks activated the IFG and the right mPFC, suggesting the mPFC may more universally function as a social inference region.

While the irony is used as a prosocial communicative tool that mitigates the face-threatening of the speaker, the deceit violates the social norm that requires the speaker to make a truthful statement. However, the understanding of both speech acts involves a contrast between what a speaker affirms and his private knowledge and requires the derivation of the shared knowledge between the speaker and the listener [10]. When the speaker produces the irony, they expect the listener to detect whereas the speaker does not expect the listener to recognize the deceit. One study explored the neural activations underlying the irony and deceitful statements [11]. Healthy individuals read statements used in sincere, deceitful, and ironic way (e.g., It's a beautiful day.). In both deceitful and ironic statements, the speaker implies the opposite of what he says [12, 13]. Compared with the since voice, both deceitful and ironic voices increased activations in the left fronto-temporal network, including the left IFG, dlPFC, and middle frontal gyrus (MFG). The IFG suggests that a demanded inferential process of the correct intended meaning from the (wrong) literal meaning of the utterance. The dlPFC suggests the involvement of executive functions to combine the inferences necessary to understand the speaker's intention to deceive with the comprehension that social norms are violated. The ironic statements uniquely activated the left MFG as compared with the deceitful statements. These findings highlight the role of prefrontal areas underlying both executive functions and social inference processes in the interpretation of pragmatic meanings from the statement.

involve the input from social interaction, the human acquisition of language-processing abilities heavily rely on the social input. One of the main functions of language is to establish, maintain, and modify social relations. The meanings that are conveyed by language are situated in social settings and are hence highly negotiable. Newly emergent research in cognitive neuroscience of language argues that the meaning at different linguistic levels depends on social interactions and ongoing representation of body actions [2]. This chapter therefore elucidates the neural representations underlying social language processing, summarizing the representative studies that showed the involvement of prefrontal regions during processing language that conveys social information or supported by social interaction. We highlight that multiple neurocognitive components underlying social functions in the prefrontal cortex have successfully guided humans to understand language in social contexts. We will extend our perspectives into (1) indirect language and social inferential networks, (2) recognizing speech/communicative acts and action-related networks, the relation between prefrontal deficits, pragmatic impairments, and the role of theory of mind (ToM) and executive functions; (3) neural correlates of reading emotion-laden literary; (4) transmission and learning of language

66 Prefrontal Cortex

in social contexts; and (5) cognitive empathy and pragmatic language processing.

mPFC may more universally function as a social inference region.

While the irony is used as a prosocial communicative tool that mitigates the face-threatening of the speaker, the deceit violates the social norm that requires the speaker to make a truthful statement. However, the understanding of both speech acts involves a contrast between

To detect that a conversational turn is intended to be ironic or sincere, the listener must go beyond the literal meaning. The medial prefrontal cortex (mPFC), together with the precuneus and bilateral temporal parietal junction (TPJ), forms the neuronal network for mentalizing that is correlated with the speaker meaning on the overhearers (e.g., [3–5]). These regions were more active when listeners heard the ironic utterances (*Tonight we gave a superb performance* said by an opera singer after a disastrous performance; [6]), and sentences with ambiguous references (*When Beyonce met Madonna she had just had a little accident at the hairdressers*) as compared with the literal or unambiguous control sentences. Some irony comprehension tasks also found the medial prefrontal cortex (mPFC) and middle temporal gyrus (MTG)/superior temporal sulcus (STS) [7]. The irony comprehension also involved areas related with the high executive demands and integrative processes, including the inferior frontal gyrus (IFG), MTG, and dorsolateral prefrontal cortex. Recognition of communication intention during language comprehension, in particular, the comprehension of a speech act, recruits extended neural networks. Uchiyama and colleagues found prominent activation in the IFG, MTG, and mPFC during recognizing ironic meaning [8]. The authors interpreted activation in the mPFC as being related with mentalizing activity, and activation in the IFG and MTG being related with activity in the semantic-executive system engaged in the semantic retrieval, selection, and evaluation during sentence comprehension. Harada et al. examined the neural correlates using the task where the participants judged whether the protagonist in a story uttered a speech act with the intention to deceive, or whether their behavior was morally acceptable [9]. The deceit recognition task activated the bilateral TPJ, inferior parietal lobule (IPL), the right MTG and dorsal lateral PFC (dlPFC), with the dlPFC activation related with the executive demands set by the task. Both tasks activated the IFG and the right mPFC, suggesting the The ability to detect the literal meaning maybe disrupted in schizophrenia patients who showed difficulties in successfully decoding meaning of ironic conversational turns [14] and in perspective taking and second-order theory of mind processes that the irony comprehension heavily relies on [14, 15]. Lesion and functional magnetic resonance imaging (fMRI) evidence has found the involvement of medial prefrontal cortex in theory of mind processing [16], and the involvement of right lateral temporal lobe [17] or the left MTG/superior temporal gyrus (STG) or the left lateral prefrontal cortex (lPFC) [18] in detecting nonliteral meanings. One study demonstrated that, as compared with literal statements, reading ironic statements ending the text vignettes activated a bilateral network including the left medial prefrontal and left inferior parietal gyri [18]. The increased activation in the mPFC suggests the involvement of second-order "theory of mind" processing in the ironic and sarcastic stimuli. The increased activation in the bilateral middle temporal gyrus in reading ironic statements were negatively associated with the reader's schizophrenic trait score (measured by schizotypal personality questionnaire, SPQ), suggesting that the more activated the bilateral MTG, the lower SPQ score when the participant read the ironic statement. These findings suggest that individuals with schizotypical personality traits are associated with a dysfunctional lateral temporal language rather than a prefrontal theory of mind network; moreover, the processing of ironic language maybe interrupted by neural mechanisms underlying the functional impairment of schizotypical personality [19]. A positive correlation was found between the activation in the left IFG when participants read irony and the SPQ possibly suggesting an involvement of additional semantic integration processes when the nonliteral sentence was encountered.

Indirect response is a "face-saving" strategy and serves as a tool for manipulating the addressee by a socially navigating individual. One study scanned the participants' brain when they listened to a reply from a job candidate that was either addressed to them (when they imagined themselves as the addressee) or to the interviewer in a job interview setting (when they overheard the conversations from the candidate and the interviewer [20]). They observed that the indirect reply, which functioned as a politeness strategy to mitigate the potential verbal threatening on the speaker's face (e.g., *I am planning to take a language course this summer*. as indirect response to: *Are you fluent in any foreign languages*? vs. direct response to *What are your plans after graduation*?), activated mPFC, bilateral IFG, bilateral TPJ, and bilateral MTG in both conversation settings. The ventral salience network (dorsal portion of insula and anterior cingulate cortex (ACC)) was additionally involved in certain social scenarios when the participant was addressed directly. These findings suggest that the face-saving indirect languages engage perspective-taking and discourse mechanisms associated with the increased inferential complexity which may be irrelevant to whether the speaker was the first person or third person involved in the comprehension. Moreover, affective processing mechanism which determines whether the participant is the direct recipient of the address, with the regions encoding emotional salience involved when the listener's evaluative process is stronger as the direct addressee toward the indirect reply. These findings suggest that the social inference and selection of the appropriate meaning may serve as crucial mechanisms that draw upon medial prefrontal cortex to resolve any types of unspecified or implicit meanings which are contextualized, including the derivation of the pragmatic implicatures in nonliteral statements.

Another fMRI study focused on the role of modality-preferential sensorimotor areas in processing meaning of abstract emotion words, such as "love," and mental words, such as "thought" [25]. While the prefrontal cortex (e.g., the dorsal lateral and prefrontal areas) served to activate the multimodal meanings regardless of word types, the sensorimotor regions (e.g., premotor areas, [26]; left posterior IFG and MFG, [27]; rostral part of ACC, [28]) were selectively engaged more in the abstract words. Participants read silently abstract emotional and mental nouns along with concrete action-related words. The regional-of-interest analysis showed that the face motor areas in the left precentral somatotopy was involved when the mental nouns and the face-related action words were encountered, while both the precentral hand and face motor areas were recruited when participants read abstract emotion words [29]. The sensorimotor systems in semantic processing are not restricted to the concrete action words but should be extended to some mental concepts. The causal role of prefrontal regions in the abstract emotion and interpersonal mental words were also demonstrated. For example, patients with a focal lesion of the left supplementary motor area (SMA) showed selective deficit in processing abstract emotional nouns. The interpersonal words (such as "convince," [30]) were found to activate the medial prefrontal, post-cingulate cortex (PCC), and orbitofrontal cortex, areas identified to be involved in mentalizing and social cognition processes. The prefrontal region, especially those which are necessary for integration of social knowledge and

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one's action, participated in the understanding of communicative (speech) acts.

**3. Prefrontal deficit, impairment in pragmatic ability, theory of** 

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

**mind, and executive function**
