The influence of context on hemispheric recruitment during metaphor processing

The Effects of Age and Reading Experience on the Lifespan Neurodevelopment for Reading Comprehension

Reading comprehension is a vital cognitive skill that individuals use throughout their lives. The neurodevelopment of reading comprehension across the lifespan, however, remains underresearched. Furthermore, factors such as maturation and experience significantly influence functional brain development. Given the complexity of reading comprehension, which incorporates lower-level word reading process and higher-level semantic integration process, our study aims to investigate how age and reading experience influence the neurobiology underpinning these two processes across the lifespan. fMRI data of 158 participants aged from 7 to 77 years were collected during a passive word viewing task and a sentence comprehension task to engage the lower- and higher-level processes, respectively. We found that the neurodevelopment of the lower-level process was primarily influenced by age, showing increased activation and connectivity with age in parieto-occipital and middle/inferior frontal lobes related to morphological-semantic mapping while decreased activation in the temporoparietal regions linked to phonological processing. However, the brain function of the higher-level process was primarily influenced by reading experience, exhibiting a greater reliance on the frontotemporal semantic network with enhanced sentence-level reading performance. Furthermore, reading experience did not significantly affect the brain function of children, but had a positive effect on young adults in the lower-level process and on middle-aged and older adults in the higher-level process. These findings indicate that the brain function for lower- and higher-level processes of reading comprehension is differently affected by maturation and reading experience, and the experience effect is contingent on age regarding the two processes.

Neural network of metaphor comprehension: an ALE meta-analysis and MACM analysis

The comprehension of metaphor, a vivid and figurative language, is a complex endeavor requiring cooperation among multiple cognitive systems. There are still many important questions regarding neural mechanisms implicated in specific types of metaphor. To address these questions, we conducted activation likelihood estimation meta-analyses on 30 studies (containing data of 480 participants) and meta-analytic connectivity modeling analyses. First, the results showed that metaphor comprehension engaged the inferior frontal gyrus, middle temporal gyrus, fusiform gyrus, lingual gyrus, and middle occipital gyrus-all in the left hemisphere. In addition to the commonly reported networks of language and attention, metaphor comprehension engaged networks of visual. Second, sub-analysis showed that the contextual complexity can modulate figurativeness, with the convergence on the left fusiform gyrus during metaphor comprehension at discourse-level. Especially, right hemisphere only showed convergence in studies of novel metaphors, suggesting that the right hemisphere is more associated with difficulty than metaphorical. The work here extends knowledge of the neural mechanisms underlying metaphor comprehension in individual brain regions and neural networks.

Neural underpinnings of processing combinatorial unstated meaning and the influence of individual cognitive style

We investigated the neurocognitive mechanisms underlying the processing of combinatorial unstated meaning. Sentences like "Charles jumped for 5 minutes." engender an iterative meaning that is not explicitly stated but enriched by comprehenders beyond simple composition. Comprehending unstated meaning involves meaning contextualization-integrative meaning search in sentential-discourse context. Meanwhile, people differ in how they process information with varying context sensitivity. We hypothesized that unstated meaning processing would vary with individual socio-cognitive propensity indexed by the Autism-Spectrum Quotient (AQ), accompanied by differential cortical engagements. Using functional magnetic resonance imaging, we examined the processing of sentences with unstated iterative meaning in typically-developed individuals and found an engagement of the fronto-parietal network, including the left pars triangularis (L.PT), right intraparietal (R.IPS), and parieto-occipital sulcus (R.POS). We suggest that the L.PT subserves a contextual meaning search, while the R.IPS/POS supports enriching unstated iteration in consideration of event durations and interval lengths. Moreover, the activation level of these regions negatively correlated with AQ. Higher AQ ties to lower L.PT activation, likely reflecting weaker context sensitivity, along with lower IPS activation, likely reflecting weaker computation of events' numerical-temporal specifications. These suggest that the L.PT and R.IPS/POS support the processing of combinatorial unstated meaning, with the activation level modulated by individual cognitive styles.

Non-literal language processing is jointly supported by the language and theory of mind networks: Evidence from a novel meta-analytic fMRI approach

Going beyond the literal meaning of language is key to communicative success. However, the mechanisms that support non-literal inferences remain debated. Using a novel meta-analytic approach, we evaluate the contribution of linguistic, social-cognitive, and executive mechanisms to non-literal interpretation. We identified 74 fMRI experiments (n = 1,430 participants) from 2001 to 2021 that contrasted non-literal language comprehension with a literal control condition, spanning ten phenomena (e.g., metaphor, irony, indirect speech). Applying the activation likelihood estimation approach to the 825 activation peaks yielded six left-lateralized clusters. We then evaluated the locations of both the individual-study peaks and the clusters against probabilistic functional atlases (cf. anatomical locations, as is typically done) for three candidate brain networks-the language-selective network (Fedorenko, Behr, & Kanwisher, 2011), which supports language processing, the Theory of Mind (ToM) network (Saxe & Kanwisher, 2003), which supports social inferences, and the domain-general Multiple-Demand (MD) network (Duncan, 2010), which supports executive control. These atlases were created by overlaying individual activation maps of participants who performed robust and extensively validated 'localizer' tasks that selectively target each network in question (n = 806 for language; n = 198 for ToM; n = 691 for MD). We found that both the individual-study peaks and the ALE clusters fell primarily within the language network and the ToM network. These results suggest that non-literal processing is supported by both i) mechanisms that process literal linguistic meaning, and ii) mechanisms that support general social inference. They thus undermine a strong divide between literal and non-literal aspects of language and challenge the claim that non-literal processing requires additional executive resources.

The Elephant in the Room: A Systematic Review of Stimulus Control in Neuro-Measurement Studies on Figurative Language Processing

The processing of metaphors and idioms has been the subject of neuroscientific research for several decades. However, results are often contradictory, which can be traced back to inconsistent terminology and stimulus control. In this systematic review of research methods, we analyse linguistic aspects of 116 research papers which used EEG, fMRI, PET, MEG, or NIRS to investigate the neural processing of the two figurative subtypes metaphor and idiom. We critically examine the theoretical foundations as well as stimulus control by performing a systematic literature synthesis according to the PRISMA guidelines. We explicitly do not analyse the findings of the studies but instead focus on four primary aspects: definitions of figurative language and its subtypes, linguistic theory behind the studies, control for factors influencing figurative language processing, and the relationship between theoretical and operational definitions. We found both a lack and a broad variety in existing definitions and operationalisation, especially in regard to familiarity and conventionality. We identify severe obstacles in the comparability and validation potential of the results of the papers in our review corpus. We propose the development of a consensus in fundamental terminology and more transparency in the reporting of stimulus design in the research on figurative language processing.

Enhanced insightfulness and neural activation induced by metaphorical solutions to appropriate mental distress problems

Although the neural correlates of novelty and appropriateness of creative insight during cognitive tasks have been investigated in several studies, they have not been examined during mental distress in a psychotherapeutic setting. This study aimed to reveal the promoting effects of novelty and appropriateness processing on therapeutic insight in a micro-psychotherapeutic setting. We examined the effects of appropriateness (between-subject factor: appropriateness group, 20 participants; inappropriateness group, 21 participants) by manipulating the preceding negative scenarios that either fit or did not fit the subsequent solutions, and those of novelty (within-subject factor) by varying the linguistic expressions for describing solutions (metaphorical, literal, or problem-restatement). Event-related functional magnetic resonance images were collected. We found the following effects: an interactive effect of the two factors on insightfulness and activation in the bilateral hippocampus and amygdala, right superior frontal gyrus, and left superior/middle temporal gyrus; a simple effect of novelty on activation in the bilateral inferior frontal gyrus, fusiform gyrus, and inferior/middle occipital gyrus; and a simple effect of appropriateness on activation in the left inferior parietal lobule. Our findings indicate that solutions with high novelty and appropriateness generate the highest levels of therapeutic insightfulness as well as the strongest activation in the hippocampus and amygdala, which may be involved in episodic memory encoding.

An Electrophysiological Abstractness Effect for Metaphorical Meaning Making

Neuroimaging studies show that metaphors activate sensorimotor areas. These findings were interpreted as metaphors contributing to conceptual thought by mapping concrete, somatosensory information onto abstract ideas. But is sensorimotor information a necessary constituent of figurative meaning? The present study employed event-related potentials (ERPs) in a divided visual field paradigm with healthy adults to explore the role of sensorimotor feature processing in the comprehension of novel metaphors via the electrophysiological concreteness effect. Participants read French, novel adjective-noun expressions that were either metaphorical (“fat sentence”) or literal (“fat hip”). While literal expressions evoked a typical concreteness effect, an enhanced frontal negativity during right hemisphere (RH) as opposed to left hemisphere (LH) presentation, metaphors showed no such sign of sensorimotor feature processing. Relative to literals, they evoked a sustained frontal negativity during LH presentation and similar amplitudes during RH presentation, but both of these effects were the greater the more abstract the metaphors were. It is the first time such an electrophysiological abstractness effect is reported, just the opposite of a concreteness effect. It is particularly noteworthy that ERPs evoked by metaphors were not contingent on figurativeness, novelty, meaningfulness, imageability, emotional valence, or arousal, only on abstractness. When compared with similarly novel literal expressions, metaphors did not evoke a typical N400 and did not activate the RH either. The findings shed new light on the neurocognitive machinery of figurative meaning construction, pervasive in everyday communication. Contrary to embodied cognition, the conceptual system might be organized around abstract representations and not sensorimotor information, even for lush, metaphorical language.

Context matters: Novel metaphors in supportive and non-supportive contexts

Creative language is defined as linguistic output that is both novel and appropriate. Metaphors are one such example of creative language in which one concept is used to express another by highlighting relevant semantic features. While novelty is an inherent property of unfamiliar metaphors, appropriateness depends on the context. The current study tests the hypothesis that the context in which metaphors are encountered affects their processing. We examined the neural effects of comprehending metaphors in context by comparing neural activations in response to novel metaphors and literal sentences that were either embedded in a meaningful narrative or in matched jabberwocky contexts. We found that the neural correlates of processing metaphoric sentences and their literal counterparts are indistinguishable when embedded in a narrative: both conditions activate bilateral areas along the anterior temporal poles, middle temporal gyri, superior temporal sulci, and the angular gyri. Metaphors embedded in a narrative as compared to their identical counterparts embedded in jabberwocky show increased responses in sensorimotor areas that correspond to the modality of the literal meaning of the target word, perhaps reflecting deeper semantic processing. Our results confirm that context affects neural mechanisms for understanding creative ideas.

Uncovering cortical activations of discourse comprehension and their overlaps with common large-scale neural networks

We conducted a meta-analysis of 78 task-based functional magnetic resonance imaging (fMRI) studies (1976 total participants) to reveal underlying brain activations and their overlap with large-scale neural networks in the brain during general discourse comprehension and its sub-processes. We found that discourse comprehension involved a neural system consisting of widely distributed brain regions that comprised not only the bilateral perisylvian language zones, but also regions in the superior and medial frontal cortex and the medial temporal lobe. Moreover, this neural system can be categorized into several sub-systems representing various sub-processes of discourse comprehension, with the left inferior frontal gyrus and middle temporal gyrus serving as core regions across all sub-processes. At a large-scale network level, we found that discourse comprehension relied most heavily on the default network, particularly on its dorsal medial subsystem. The pattern associated with large-scale network cooperation varied according to the respective sub-processes required. Our results reveal the functional dissociation within the discourse comprehension neural system and highlight the flexible involvements of large-scale networks.

Is there a prediction network? Meta-analytic evidence for a cortical-subcortical network likely subserving prediction

Predictive coding is an increasingly influential and ambitious concept in neuroscience viewing the brain as a 'hypothesis testing machine' that constantly strives to minimize prediction error, the gap between its predictions and the actual sensory input. Despite the invaluable contribution of this framework to the formulation of brain function, its neuroanatomical foundations have not been fully defined. To address this gap, we conducted activation likelihood estimation (ALE) meta-analysis of 39 neuroimaging studies of three functional domains (action perception, language and music) inherently involving prediction. The ALE analysis revealed a widely distributed brain network encompassing regions within the inferior and middle frontal gyri, anterior insula, premotor cortex, pre-supplementary motor area, temporoparietal junction, striatum, thalamus/subthalamus and the cerebellum. This network is proposed to subserve domain-general prediction and its relevance to motor control, attention, implicit learning and social cognition is discussed in light of the predictive coding scheme. Better understanding of the presented network may help advance treatments of neuropsychiatric conditions related to aberrant prediction processing and promote cognitive enhancement in healthy individuals.

Functionally distinct language and Theory of Mind networks are synchronized at rest and during language comprehension

Communication requires the abilities to generate and interpret utterances and to infer the beliefs, desires, and goals of others ("Theory of Mind"; ToM). These two abilities have been shown to dissociate: individuals with aphasia retain the ability to think about others' mental states; and individuals with autism are impaired in social reasoning, but their basic language processing is often intact. In line with this evidence from brain disorders, functional MRI (fMRI) studies have shown that linguistic and ToM abilities recruit distinct sets of brain regions. And yet, language is a social tool that allows us to share thoughts with one another. Thus, the language and ToM brain networks must share information despite being implemented in distinct neural circuits. Here, we investigated potential interactions between these networks during naturalistic cognition using functional correlations in fMRI. The networks were functionally defined in individual participants, in terms of preference for sentences over nonwords for language, and for belief inference over physical-event processing for ToM, with both a verbal and a nonverbal paradigm. Although, across experiments, interregion correlations within each network were higher than between-network correlations, we also observed above-baseline synchronization of blood oxygenation level-dependent signal fluctuations between the two networks during rest and story comprehension. This synchronization was functionally specific: neither network was synchronized with the executive control network (functionally defined in terms of preference for a harder over easier version of an executive task). Thus, coordination between the language and ToM networks appears to be an inherent and specific characteristic of their functional architecture. NEW & NOTEWORTHY Humans differ from nonhuman primates in their abilities to communicate linguistically and to infer others' mental states. Although linguistic and social abilities appear to be interlinked onto- and phylogenetically, they are dissociated in the adult human brain. Yet successful communication requires language and social reasoning to work in concert. Using functional MRI, we show that language regions are synchronized with social regions during rest and language comprehension, pointing to a possible mechanism for internetwork interaction.

The Artery of Aphasia, A Uniquely Sensitive Posterior Temporal Middle Cerebral Artery Branch that Supplies Language Areas in the Brain: Anatomy and Report of Four Cases

BACKGROUND

Arterial disruption during brain surgery can cause devastating injuries to wide expanses of white and gray matter beyond the tumor resection cavity. Such damage may occur as a result of disrupting blood flow through en passage arteries. Identification of these arteries is critical to prevent unforeseen neurologic sequelae during brain tumor resection. In this study, we discuss one such artery, termed the artery of aphasia (AoA), which when disrupted can lead to receptive and expressive language deficits.

METHODS

We performed a retrospective review of all patients undergoing an awake craniotomy for resection of a glioma by the senior author from 2012 to 2018. Patients were included if they experienced language deficits secondary to postoperative infarction in the left posterior temporal lobe in the distribution of the AoA. The gross anatomy of the AoA was then compared with activation likelihood estimations of the auditory and semantic language networks using coordinate-based meta-analytic techniques.

RESULTS

We identified 4 patients with left-sided posterior temporal artery infarctions in the distribution of the AoA on diffusion-weighted magnetic resonance imaging. All 4 patients developed substantial expressive and receptive language deficits after surgery. Functional language improvement occurred in only 2/4 patients. Activation likelihood estimations localized parts of the auditory and semantic language networks in the distribution of the AoA.

CONCLUSIONS

The AoA is prone to blood flow disruption despite benign manipulation. Patients seem to have limited capacity for speech recovery after intraoperative ischemia in the distribution of this artery, which supplies parts of the auditory and semantic language networks.

Shared genetic aetiology between cognitive performance and brain activations in language and math tasks

Cognitive performance is highly heritable. However, little is known about common genetic influences on cognitive ability and brain activation when engaged in a cognitive task. The Human Connectome Project (HCP) offers a unique opportunity to study this shared genetic etiology with an extended pedigree of 785 individuals. To investigate this common genetic origin, we took advantage of the HCP dataset, which includes both language and mathematics activation tasks. Using the HCP multimodal parcellation, we identified areals in which inter-individual functional MRI (fMRI) activation variance was significantly explained by genetics. Then, we performed bivariate genetic analyses between the neural activations and behavioral scores, corresponding to the fMRI task accuracies, fluid intelligence, working memory and language performance. We observed that several parts of the language network along the superior temporal sulcus, as well as the angular gyrus belonging to the math processing network, are significantly genetically correlated with these indicators of cognitive performance. This shared genetic etiology provides insights into the brain areas where the human-specific genetic repertoire is expressed. Studying the association of polygenic risk scores, using variants associated with human cognitive ability and brain activation, would provide an opportunity to better understand where these variants are influential.

A Quantitative Meta-analysis of Neuroimaging Studies of Pragmatic Language Comprehension: In Search of a Universal Neural Substrate

Pragmatics may be defined as the ability to communicate by expressing and recognizing intentions. The objective of this meta-analysis was to identify neural substrates for comprehension of pragmatic content in general, as well as the differences between pragmatic forms, and to describe if there is differential recruitment of brain areas according to natural language. This meta-analysis included 48 functional magnetic resonance imaging studies that reported pragmatic versus literal language contrasts. The pragmatic forms were speech acts, metaphors, idioms, and irony. Effect Size-Signed Differential Mapping software was used to calculate the mean for all contrasts as well as for each pragmatic form, and make comparisons among all forms. Due to variations in pragmatic content configuration such as natural language, stimulus modality, and writing systems, these variations were also analyzed with subgroups' analyses. The analyses found a highly reproducible bilateral fronto-temporal and medial prefrontal cortex network for pragmatic comprehension. Each pragmatic form showed a specific convergence pattern within this bilateral network. Natural language analyses showed that fronto-temporal regions were recruited by Germanic languages, while only left frontal areas were recruited by Romance languages, and right medial prefrontal cortex by Japanese. In conclusion, pragmatic language comprehension involves classical language areas in bilateral perisylvian regions, along with the medial prefrontal cortex, an area involved in social cognition. Together, these areas could represent the "pragmatic language network". Nonetheless, when proposing a universal neural substrate for all forms of pragmatic language, the diversity among studies in terms of pragmatic form, and configuration, must be taken into consideration.

Executive Functions Brain System: An Activation Likelihood Estimation Meta-analytic Study

Background and objective

To characterize commonalities and differences between two executive functions: reasoning and inhibitory control.

Methods

A total of 5,974 participants in 346 fMRI experiments of inhibition or reasoning were selected. First level analysis consisted of Analysis of Likelihood Estimation (ALE) studies performed in two pooled data groups: (a) brain areas involved in reasoning and (b) brain areas involved in inhibition. Second level analysis consisted of two contrasts: (i) brain areas involved in reasoning but not in inhibition and (ii) brain areas involved in inhibition but not in reasoning. Lateralization Indexes were calculated.

Results

Four brain areas appear as the most critical: the dorsolateral aspect of the frontal lobes, the superior parietal lobules, the mesial aspect of the premotor area (supplementary motor area), and some subcortical areas, particularly the putamen and the thalamus. ALE contrasts showed significant differentiation of the networks, with the reasoning > inhibition-contrast showing a predominantly leftward participation, and the inhibition > reasoning-contrast, a clear right advantage.

Conclusion

Executive functions are mediated by sizable brain areas including not only cortical, but also involving subcortical areas in both hemispheres. The strength of activation shows dissociation between the hemispheres for inhibition (rightward) and reasoning (leftward) functions.

Factors Influencing Right Hemisphere Engagement During Metaphor Comprehension

Although the left hemisphere is critical for language, clinical, behavioral, and neuroimaging research suggest that the right hemisphere also contributes to language comprehension. In particular, research has suggested that figurative language may be one type of language that preferentially engages right hemisphere regions. However, there is disagreement about whether these regions within the right hemisphere are sensitive to figurative language per se or to other factors that co-vary with figurativeness. In this article, we will review the neuroimaging literature on figurative language processing, focusing on metaphors, within the context of several theoretical perspectives that have been proposed about hemispheric function in language. Then we will examine three factors that may influence right hemisphere engagement: novelty, task difficulty, and context. We propose that factors that increase integration demands drive right hemisphere involvement in language processing, and that such recruitment is not limited to figurative language.

Haemodynamic and electrophysiological markers of pragmatic language comprehension in schizophrenia

OBJECTIVES

The present study aimed at investigating neurophysiological markers of language perception in schizophrenia using simultaneous near-infrared spectroscopy (NIRS) and event-related potentials (ERPs), which have been proven to be useful for studying language processing abilities in psychiatric patients. The study shall help to integrate previous findings from ERP and fMRI studies on figurative language comprehension in schizophrenia and elucidate how electrophysiological and haemodynamic markers of language processing are related.

METHODS

Twenty-two healthy subjects and 22 schizophrenia patients judged 120 sentences regarding their meaningfulness. Phrases were literal, metaphoric, or meaningless. EEG-fNIRS signals were recorded throughout the entire experiment.

RESULTS

Schizophrenia patients showed deficient and delayed sentence comprehension. Both the early N400 and left-hemispheric activation during language comprehension were altered in patients. Correlation analyses showed that metaphor-related ERPs were strongly linked to haemodynamic cortical activity in healthy subjects, but not in patients.

CONCLUSIONS

Our results indicate group differences in cortical electrophysiological and haemodynamic activation that represent rather general impairments in the processing of complex language. Simultaneous EEG/NIRS applications are useful to depict these neural markers and to investigate their relationship. Future studies are needed to clarify the nature of respective anomalies and their potential as putative neural markers in schizophrenia research.

Flying under the radar: figurative language impairments in focal lesion patients

Despite the prevalent and natural use of metaphor in everyday language, the neural basis of this powerful communication device remains poorly understood. Early studies of brain-injured patients suggested the right hemisphere plays a critical role in metaphor comprehension, but more recent patient and neuroimaging studies do not consistently support this hypothesis. One explanation for this discrepancy is the challenge in designing optimal tasks for brain-injured populations. As traditional aphasia assessments do not assess figurative language comprehension, we designed a new metaphor comprehension task to consider whether impaired metaphor processing is missed by standard clinical assessments. Stimuli consisted of 60 pairs of moderately familiar metaphors and closely matched literal sentences. Sentences were presented visually in a randomized order, followed by four adjective-noun answer choices (target + three foil types). Participants were instructed to select the phrase that best matched the meaning of the sentence. We report the performance of three focal lesion patients and a group of 12 healthy, older controls. Controls performed near ceiling in both conditions, with slightly more accurate performance on literal than metaphoric sentences. While the Western Aphasia Battery (Kertesz, 1982) and the objects and actions naming battery (Druks and Masterson, 2000) indicated minimal to no language difficulty, our metaphor comprehension task indicated three different profiles of metaphor comprehension impairment in the patients’ performance. Single case statistics revealed comparable impairment on metaphoric and literal sentences, disproportionately greater impairment on metaphors than literal sentences, and selective impairment on metaphors. We conclude our task reveals that patients can have selective metaphor comprehension deficits. These deficits are not captured by traditional neuropsychological language assessments, suggesting overlooked communication difficulties.

Differential bilateral involvement of the parietal gyrus during predicative metaphor processing: an auditory fMRI study

Despite the growing literature on figurative language processing, there is still debate as to which cognitive processes and neural bases are involved. Furthermore, most studies have focused on nominal metaphor processing without any context, and very few have used auditory presentation. We therefore investigated the neural bases of the comprehension of predicative metaphors presented in a brief context, in an auditory, ecological way. The comprehension of their literal counterparts served as a control condition. We also investigated the link between working memory and verbal skills and regional activation. Comparisons of metaphorical and literal conditions revealed bilateral activation of parietal areas including the left angular (lAG) and right inferior parietal gyri (rIPG) and right precuneus. Only verbal skills were associated with lAG (but not rIPG) activation. These results indicated that predicative metaphor comprehension share common activations with other metaphors. Furthermore, individual verbal skills could have an impact on figurative language processing.

Why people drink shampoo? Food Imitating Products are fooling brains and endangering consumers for marketing purposes

A Food Imitating Product (FIP) is a household cleaner or a personal care product that exhibits food attributes in order to enrich consumption experience. As revealed by many cases worldwide, such a marketing strategy led to unintentional self-poisonings and deaths. FIPs therefore constitute a very serious health and public policy issue. To understand why FIPs are a threat, we first conducted a qualitative analysis on real-life cases of household cleaners and personal care products-related phone calls at a poison control center followed by a behavioral experiment. Unintentional self-poisoning in the home following the accidental ingestion of a hygiene product by a healthy adult is very likely to result from these products being packaged like foodstuffs. Our hypothesis is that FIPs are non-verbal food metaphors that could fool the brain of consumers. We therefore conducted a subsequent functional neuroimaging (fMRI) experiment that revealed how visual processing of FIPs leads to cortical taste inferences. Considered in the grounded cognition perspective, the results of our studies reveal that healthy adults can unintentionally categorize a personal care product as something edible when a food-like package is employed to market nonedible and/or dangerous products. Our methodology combining field (qualitative) and laboratory (behavioral and functional neuroimaging) findings could be of particular relevance for policy makers, as it can help screening products prior to their market release – e.g. the way they are packaged and how they can potentially confuse the mind of consumers – and therefore save lives.

Rigidity, chaos and integration: hemispheric interaction and individual differences in metaphor comprehension

Neurotypical individuals cope flexibly with the full range of semantic relations expressed in human language, including metaphoric relations. This impressive semantic ability may be associated with distinct and flexible patterns of hemispheric interaction, including higher right hemisphere (RH) involvement for processing novel metaphors. However, this ability may be impaired in specific clinical conditions, such as Asperger syndrome (AS) and schizophrenia. The impaired semantic processing is accompanied by different patterns of hemispheric interaction during semantic processing, showing either reduced (in Asperger syndrome) or excessive (in schizophrenia) RH involvement. This paper interprets these individual differences using the terms Rigidity, Chaos and Integration, which describe patterns of semantic memory network states that either lead to semantic well-being or are disruptive of it. We argue that these semantic network states lie on a rigidity-chaos semantic continuum. We define these terms via network science terminology and provide network, cognitive and neural evidence to support our claim. This continuum includes left hemisphere (LH) hyper-rigid semantic memory state on one end (e.g., in persons with AS), and RH chaotic and over-flexible semantic memory state on the other end (e.g., in persons with schizophrenia). In between these two extremes lie different states of semantic memory structure which are related to individual differences in semantic creativity. We suggest that efficient semantic processing is achieved by semantic integration, a balance between semantic rigidity and semantic chaos. Such integration is achieved via intra-hemispheric communication. However, impairments to this well-balanced and integrated pattern of hemispheric interaction, e.g., when one hemisphere dominates the other, may lead to either semantic rigidity or semantic chaos, moving away from semantic integration and thus impairing the processing of metaphoric language.

The neurobiology of language beyond single words

A hallmark of human language is that we combine lexical building blocks retrieved from memory in endless new ways. This combinatorial aspect of language is referred to as unification. Here we focus on the neurobiological infrastructure for syntactic and semantic unification. Unification is characterized by a high-speed temporal profile including both prediction and integration of retrieved lexical elements. A meta-analysis of numerous neuroimaging studies reveals a clear dorsal/ventral gradient in both left inferior frontal cortex and left posterior temporal cortex, with dorsal foci for syntactic processing and ventral foci for semantic processing. In addition to core areas for unification, further networks need to be recruited to realize language-driven communication to its full extent. One example is the theory of mind network, which allows listeners and readers to infer the intended message (speaker meaning) from the coded meaning of the linguistic utterance. This indicates that sensorimotor simulation cannot handle all of language processing.

Written distractor words influence brain activity during overt picture naming

Language production requires multiple stages of processing (e.g., semantic retrieval, lexical selection), each of which may involve distinct brain regions. Distractor words can be combined with picture naming to examine factors that influence language production. Phonologically-related distractors have been found to speed picture naming (facilitation), while slower response times and decreased accuracy (interference) generally occur when a distractor is categorically related to the target image. However, other types of semantically-related distractors have been reported to produce a facilitative effect (e.g., associative, part-whole). The different pattern of results for different types of semantically-related distractors raises the question about how the nature of the semantic relation influences the effect of the distractor. To explore the nature of these semantic effects further, we used functional MRI to examine the influence of four types of written distractors on brain activation during overt picture naming. Distractors began with the same sound, were categorically-related, part of the object to be named, or were unrelated to the picture. Phonologically-related trials elicited greater activation than both semantic conditions (categorically-related and part-whole) in left insula and bilateral parietal cortex, regions that have been attributed to phonological aspects of production and encoding, respectively. Semantic conditions elicited greater activation than phonological trials in left posterior MTG, a region that has been linked to concept retrieval and semantic integration. Overall, the two semantic conditions did not differ substantially in their functional activation which suggests a similarity in the semantic demands and lexical competition across these two conditions.

Very early processing of emotional words revealed in temporoparietal junctions of both hemispheres by EEG and TMS

We investigate the contribution of both hemispheres in a lateralised lexical decision paradigm with emotional and neutral words in healthy volunteers. In a first experiment, high-density EEG analysis using source imaging methods revealed early specific participation of the temporoparietal junctions (TPJ) in both hemispheres for the detection of words. Then, in an event-related transcranial magnetic stimulation experiment with the same task, the disruption of left or right TPJ compared with a control stimulation over the vertex showed a slowing that is more pronounced when words are emotional and presented in the left visual field (LVF). This indicates that interference with both left and right TPJ results in impaired processing of words that were presented to the LVF. In addition, these results point to a specific cooperative contribution of the right hemisphere in the processing of words with emotional content compared with neutral words at very early stages. Results from the two experiments can be integrated in a brain-based spatiotemporal model of the early detection of written words.

Lateralized processing of novel metaphors: disentangling figurativeness and novelty

One of the intriguing and sometimes controversial findings in figurative language research is a right-hemisphere processing advantage for novel metaphors. The current divided visual field study introduced novel literal expressions as a control condition to assess processing novelty independent of figurativeness. Participants evaluated word pairs belonging to one of the five categories: (1) conventional metaphorical, (2) conventional literal, (3) novel metaphorical, (4) novel literal, and (5) unrelated expressions in a semantic decision task. We presented expressions without sentence context and controlled for additional factors including emotional valence, arousal, and imageability that could potentially influence hemispheric processing. We also utilized an eye-tracker to ensure lateralized presentation. We did not find the previously reported right-hemispherical processing advantage for novel metaphors. Processing was faster in the left hemisphere for all types of word pairs, and accuracy was also higher in the right visual field - left hemisphere. Novel metaphors were processed just as fast as novel literal expressions, suggesting that the primary challenge during the comprehension of novel expressions is not a serial processing of salience, but perhaps a more left hemisphere weighted semantic integration. Our results cast doubt on the right-hemisphere theory of metaphors, and raise the possibility that other uncontrolled variables were responsible for previous results. The lateralization of processing of two word expressions seems to be more contingent on the specific task at hand than their figurativeness or saliency.

Impairments in proverb interpretation following focal frontal lobe lesions

The proverb interpretation task (PIT) is often used in clinical settings to evaluate frontal "executive" dysfunction. However, only a relatively small number of studies have investigated the relationship between frontal lobe lesions and performance on the PIT. We compared 52 patients with unselected focal frontal lobe lesions with 52 closely matched healthy controls on a proverb interpretation task. Participants also completed a battery of neuropsychological tests, including a fluid intelligence task (Raven's Advanced Progressive Matrices). Lesions were firstly analysed according to a standard left/right sub-division. Secondly, a finer-grained analysis compared the performance of patients with medial, left lateral and right lateral lesions with healthy controls. Thirdly, a contrast of specific frontal subgroups compared the performance of patients with medial lesions with patients with lateral frontal lesions. The results showed that patients with left frontal lesions were significantly impaired on the PIT, while in patients with right frontal lesions the impairments approached significance. Medial frontal patients were the only frontal subgroup impaired on the PIT, relative to healthy controls and lateral frontal patients. Interestingly, an error analysis indicated that a significantly higher number of concrete responses were found in the left lateral subgroup compared to healthy controls. We found no correlation between scores on the PIT and on the fluid intelligence task. Overall our results suggest that specific regions of the frontal lobes contribute to the performance on the PIT.

The role of the right hemisphere in metaphor comprehension: a meta-analysis of functional magnetic resonance imaging studies

The role of the right hemisphere (RH) in metaphor comprehension is still controversial. Numerous neuroimaging studies have found that conventionality, sentential context, and task demand can influence the involvement of the RH in metaphor processing. The current meta-analysis used foci from 17 original functional magnetic resonance imaging studies to identify what factors modulate the involvement of the RH in metaphor processing. Activation likelihood estimation was used for quantification. We focused on the contrast of metaphorical meaning processing versus literal meaning processing and calculated the meta-analysis effects when (1) metaphorical meaning is conventional, (2) metaphorical meaning is novel, (3) metaphorical and literal meaning are presented in words, (4) metaphorical and literal meaning are presented in sentential context, (5) task is valence judgment, and (6) task is semantic relatedness judgment. The results indicated that the RH only showed significant effects in metaphor processing when the metaphorical meaning is novel, when metaphorical meaning is presented in sentential context, and when the task is semantic relatedness judgment. The effects were located in right fronto-temporal regions, including inferior frontal gyrus, middle frontal gyrus, insula, superior temporal gyrus, and middle temporal gyrus. These results suggest that conventionality, contextual complexity, and task demand can modulate the effect of figurativeness and influence the involvement of RH in metaphor comprehension. The main role of the RH in metaphor processing is related with activating broad semantic fields and integrating concepts that may have distant semantic relations, and hence provide support for the view that the RH is responsible for processing coarse semantic information in language comprehension.