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• Young adults are sensitive to the reducibility of uncertainty during belief updating. • Updating processes are quasi-optimal and valence-dependent. • Neural responses in frontoparietal regions show valence-dependent recruitments. • Valence asymmetry at behavioral and neural levels is correlated. Selective use of new information is crucial for adaptive decision-making. Combining a gamble bidding task with assessing cortical responses using functional near-infrared spectroscopy (fNIRS), we investigated potential effects of information valence on behavioral and neural processes of belief and value updating during uncertainty reduction in young adults. By modeling changes in the participants' expressed subjective values using a Bayesian model, we dissociated processes of (i) updating beliefs about statistical properties of the gamble, (ii) updating values of a gamble based on new information about its winning probabilities, as well as (iii) expectancy violation. The results showed that participants used new information to update their beliefs and values about the gambles in a quasi-optimal manner, as reflected in the selective updating only in situations with reducible uncertainty. Furthermore, their updating was valence-dependent: information indicating an increase in winning probability was underweighted, whereas information about a decrease in winning probability was updated in good agreement with predictions of the Bayesian decision theory. Results of model-based and moderation analyses showed that this valence-dependent asymmetry was associated with a distinct contribution of expectancy violation, besides belief updating, to value updating after experiencing new positive information regarding winning probabilities. In line with the behavioral results, we replicated previous findings showing involvements of frontoparietal brain regions in the different components of updating. Furthermore, this study provided novel results suggesting a valence-dependent recruitment of brain regions. Individuals with stronger oxyhemoglobin responses during value updating was more in line with predictions of the Bayesian model while integrating new information that indicates an increase in winning probability. Taken together, this study provides first results showing expectancy violation as a contributing factor to sub-optimal valence-dependent updating during uncertainty reduction and suggests limitations of normative Bayesian decision theory. [ABSTRACT FROM AUTHOR]

• Positive judgments of ambiguous faces had strong fMRI activation in the CO network. • Accompanied by a second, late peak following final decision on emotional valence. • Supports the initial negativity hypothesis, showing positivity is a controlled process. • CO network activation reflects reporting of valence decision late in the trial. Cortical task control networks, including the cingulo-opercular (CO) network play a key role in decision-making across a variety of functional domains. In particular, the CO network functions in a performance reporting capacity that supports successful task performance, especially in response to errors and ambiguity. In two studies testing the contribution of the CO network to ambiguity processing, we presented a valence bias task in which masked clearly and ambiguously valenced emotional expressions were slowly revealed over several seconds. This slow reveal task design provides a window into the decision-making mechanisms as they unfold over the course of a trial. In the main study, the slow reveal task was administered to 32 young adults in the fMRI environment and BOLD time courses were extracted from regions of interest in three control networks. In a follow-up study, the task was administered to a larger, online sample (n = 81) using a more extended slow reveal design with additional unmasking frames. Positive judgments of surprised faces were uniquely accompanied by slower response times and strong, late activation in the CO network. These results support the initial negativity hypothesis, which posits that the default response to ambiguity is negative and positive judgments are associated with a more effortful controlled process, and additionally suggest that this controlled process is mediated by the CO network. Moreover, ambiguous trials were characterized by a second CO response at the end of the trial, firmly placing CO function late in the decision-making process. [ABSTRACT FROM AUTHOR]

Abstract We are often presented with choices that differ in their more immediate versus future consequences. Interestingly, in everyday-life, ambiguity about the exact timing of such consequences frequently occurs, yet it remains unknown whether and how time-ambiguity influences decisions and their underlying neural correlates. We developed a novel intertemporal fMRI choice task in which participants make choices between sooner-smaller (SS) versus later-larger (LL) monetary rewards with systematically varying levels of time-ambiguity. Across trials, delay information of the SS, the LL, or both rewards was either exact (e.g., in 5 weeks), of low ambiguity (4 week range: e.g., in 3–7 weeks), or of high ambiguity (8 week range: e.g., in 1–9 weeks). Choice behavior showed that the majority of participants preferred options with exact delays over those with ambiguous delays, indicating time-ambiguity aversion. Consistent with these results, the ventromedial prefrontal cortex showed decreased activation during ambiguous versus exact trials. In contrast, intraparietal sulcus activation increased during ambiguous versus exact trials. Furthermore, exploratory analyses suggest that more time-ambiguity averse participants show more insula and dorsolateral prefrontal cortex activation during subjective value (SV)-coding of ambiguous versus exact trials. Lastly, the best-fitting computational choice models indicate that ambiguity impacts the SV of options via time perception or via an additive ambiguity-related penalty term. Together, these results provide the first behavioral and neural signatures of time-ambiguity, pointing towards a unique profile that is distinct from impatience. Since time-ambiguity is ubiquitous in real-life, it likely contributes to shortsighted decisions above and beyond delay-discounting. Highlights • We investigate time-ambiguity: uncertainty about when an outcome will occur. • Time-ambiguity is aversive, impacting choice behavior and reducing subjective value. • Time-ambiguity shows a neurobehavioral signature distinct from that of impatience. • Time-ambiguity is associated with increased IPS and decreased vmPFC activation. • Individual time-ambiguity preferences appear to modulate dlPFC and insula activity. [ABSTRACT FROM AUTHOR]

Although many neuroimaging studies have investigated adolescent risk taking, few studies have dissociated between decision-making under risk (known probabilities) and ambiguity (unknown probabilities). Furthermore, which brain regions are sensitive to individual differences in task-related and self-reported risk taking remains elusive. We presented 198 adolescents (11–24 years, an age-range in which individual differences in risk taking are prominent) with an fMRI paradigm that separated decision-making (choosing to gamble or not) and reward outcome processing (gains, no gains) under risky and ambiguous conditions, and related this to task-related and self-reported risk taking. We observed distinct neural mechanisms underlying risky and ambiguous gambling, with risk more prominently associated with activation in parietal cortex, and ambiguity more prominently with dorsolateral prefrontal cortex (PFC), as well as medial PFC during outcome processing. Individual differences in task-related risk taking were positively associated with ventral striatum activation in the decision phase, specifically for risk, and negatively associated with insula and dorsomedial PFC activation, specifically for ambiguity. Moreover, dorsolateral PFC activation in the outcome phase seemed a prominent marker for individual differences in task-related risk taking under ambiguity as well as self-reported daily-life risk taking, in which greater risk taking was associated with reduced activation in dorsolateral PFC. Together, this study demonstrates the importance of considering multiple risk-taking measures, and contextual moderators, in understanding the neural mechanisms underlying adolescent risk taking. [ABSTRACT FROM AUTHOR]

People often make decisions in the face of ambiguous information, but it remains unclear how ambiguity is represented in the brain. We used three types of ambiguous stimuli and combined EEG and fMRI to examine the neural representation of perceptual decisions under ambiguity. We identified a late positive potential, the LPP, which differentiated levels of ambiguity, and which was specifically associated with behavioral judgments about choices that were ambiguous, rather than passive perception of ambiguous stimuli. Mediation analyses together with two further control experiments confirmed that the LPP was generated only when decisions are made (not during mere perception of ambiguous stimuli), and only when those decisions involved choices on a dimension that is ambiguous. A further control experiment showed that a stronger LPP arose in the presence of ambiguous stimuli compared to when only unambiguous stimuli were present. Source modeling suggested that the LPP originated from multiple loci in cingulate cortex, a finding we further confirmed using fMRI and fMRI-guided ERP source prediction. Taken together, our findings argue for a role of an LPP originating from cingulate cortex in encoding decisions based on task-relevant perceptual ambiguity, a process that may in turn influence confidence judgment, response conflict, and error correction. [ABSTRACT FROM AUTHOR]

The brain is capable of producing coordinated fast changing neural dynamics across multiple brain regions in order to adapt to rapidly changing environments. However, it is non-trivial to identify multiregion dynamics at fast sub-second time-scales in electrophysiological data. We propose a method that, with no knowledge of any task timings, can simultaneously identify and describe fast transient multiregion dynamics in terms of their temporal, spectral and spatial properties. The approach models brain activity using a discrete set of sequential states, with each state distinguished by its own multiregion spectral properties. This can identify potentially very short-lived visits to a brain state, at the same time as inferring the state's properties, by pooling over many repeated visits to that state. We show how this can be used to compute state-specific measures such as power spectra and coherence. We demonstrate that this can be used to identify short-lived transient brain states with distinct power and functional connectivity (e.g., coherence) properties in an MEG data set collected during a volitional motor task. [ABSTRACT FROM AUTHOR]

Studies on decision-making under uncertainty have mainly focused on understanding preferences for either risk or ambiguity using standard lottery designs. However, people often face uncertainty that directly stems from interacting with other people, which may be processed differently from lottery-based uncertainty. Here, we substantially extend the investigation of uncertainty by examining a fourfold pattern of the sources and the types of uncertainty, assessing behavioral and neural responses to both risk and ambiguity across both social and non-social contexts. A key element in our research design was to control for participants' naturally occurring social beliefs, and taking these a priori beliefs into account allow us to elicit individual preferences in accordance with economic approaches that stress the dynamics of ambiguity preference as a function of underlying likelihoods. Using this design, we find a behavioral main effect of ambiguity aversion, with increasing ambiguity aversion as a function of higher beliefs regarding the likelihood of reciprocity, and related neural activity in the right IPS. This brain region was primarily involved when participants experienced lottery-based uncertainty as opposed to social uncertainty. However, we found that the right IFG was more involved when participants made decisions under social, as compared to non-social, uncertainty. Overall, therefore, the IPS may activate an analytic mindset, which might resonate more with a lottery than a social context, whereas the IFG is engaged when the context requires players to resolve uncertainty, such as unraveling the intentions behind the choice of another person. [ABSTRACT FROM AUTHOR]

The balance between automatic and controlled processing is essential to human flexible but optimal behavior. On the one hand, the automation of habitual behavior and processing is indispensable, and, on the other hand, strategic processing is needed in light of unexpected, conflicting, or new situations. Using ultra-high-field high-resolution functional magnetic resonance imaging (7T-fMRI), the present study examined the role of subcortical structures in mediating this balance. Participants were asked to judge the congruency of sentences containing a semantically ambiguous or unambiguous word. Ambiguous sentences had three possible resolutions: dominant meaning, subordinate meaning, and incongruent. The dominant interpretation represents the most habitual response, whereas both the subordinate and incongruent options clash with this automatic response, and, hence, require cognitive control. Moreover, the subordinate resolution entails a less expected but correct outcome, while the incongruent condition is simply wrong. The current results reveal the involvement of the anterior dorsomedial striatum in modulating and resolving conflict between actual and expected outcomes, and highlight the importance of cortical and subcortical cooperation in this process. [ABSTRACT FROM AUTHOR]

Abstract: We report experiments designed to learn whether different kinds of perceptually unstable visual images engage different neural mechanisms. 21 subjects viewed two types of bi-stable images while we scanned the activity in their brains with functional magnetic resonance imaging (fMRI); in one (intra-categorical type) the two percepts remained within the same category (e.g. face–face) while in the other (cross-categorical type) they crossed categorical boundaries (e.g. face–body). The results showed that cross- and intra-categorical reversals share a common reversal-related neural circuitry, which includes fronto-parietal cortex and primary visual cortex (area V1). Cross-categorical reversals alone engaged additional areas, notably anterior cingulate cortex and superior temporal gyrus, which have been posited to be involved in conflict resolution. [Copyright &y& Elsevier]

Abstract: The time-line of lexical ambiguity resolution in bilateral neuronal networks was investigated using magnetoencephalography (MEG) in a semantic decision task. Dominant and subordinate associations of ambiguous words are considered to be processed in the left and right hemispheres, respectively. In the experiment, ambiguous words were followed by dominant or subordinate associations (manipulated between blocks) or by unrelated target words, and participants (N=25) decided whether the words in each pair were related or not. Subordinate meaning blocks elicited greater changes in the magnetic fields relative to dominant ones over the right, but not the left hemisphere (LH) at 150–235ms from target onset, a time window corresponding to the M/N170 M/EEG component. Beamforming analysis localized the differential right hemisphere (RH) activity at the perisylvian area, including the homologue regions of Broca's and Wernicke's. At a later stage (235–390ms) there was no significant difference between the two meaning conditions. We suggest that the RH language regions assist the LH in integrating subordinate disambiguating clues to preceding context during the M170 time window. [Copyright &y& Elsevier]

Abstract: Understanding the relevant meaning of a word with different meanings (homonym) in a given context requires activation of the neural representations of the relevant meaning and inhibition of the irrelevant meaning. The cognitive demand of such disambiguation is highest when the dominant, yet contextually irrelevant meaning of a polar homonym must be suppressed. This central process (semantic inhibition) for lexico-semantic ambiguity resolution was monitored with fMRI during semantic context verifications. Twenty-two healthy volunteers decided whether congruent or incongruent target words fitted into the contexts established by preceding sentences. Half of the sentences ended with a homonym, thereby allowing to cross the factors ambiguity and semantic congruency. BOLD increases related to the inhibitory attentional control over non-selected meanings during ambiguity processing occurred in a brain network including left dorsolateral prefrontal cortex (DLPFC), bilateral angular gyrus (AG), bilateral anterior superior temporal gyrus (aSTG) as well as right ventromedial temporal lobe. In left DLPFC (BA 46/9) and left AG (BA 39) BOLD activity to target words of the incongruent-ambiguous condition correlated with the individual amount of semantic interference experienced by the subjects. BOLD increases of incongruent versus congruent semantic verifications occurred in bilateral inferior frontal gyrus. The results of the present study suggest a specific role of left DLPFC and AG in the resolution of semantic interference from contextually inappropriate homonym meanings. These fronto-parietal areas might exert inhibitory control over temporal regions in service of attentional selection between relevant and irrelevant homonym meanings, by creating a sufficient activation difference between their respective representations. [Copyright &y& Elsevier]

Risk and ambiguity are inherent in virtually all human decision-making. Risk refers to a situation in which we know the precise probability of potential outcomes of each option, whereas ambiguity refers to a situation in which outcome probabilities are not known. A large body of research has shown that individuals prefer known risks to ambiguity, a phenomenon known as ambiguity aversion. One heated debate concerns whether risky and ambiguous decisions rely on the same or distinct neural circuits. In the current meta-analyses, we integrated the results of neuroimaging research on decision-making under risk (n = 69) and ambiguity (n = 31). Our results showed that both processing of risk and ambiguity showed convergence in anterior insula, indicating a key role of anterior insula in encoding uncertainty. Risk additionally engaged dorsomedial prefrontal cortex (dmPFC) and ventral striatum, whereas ambiguity specifically recruited the dorsolateral prefrontal cortex (dlPFC), inferior parietal lobe (IPL) and right anterior insula. Our findings demonstrate overlapping and distinct neural substrates underlying different types of uncertainty, guiding future neuroimaging research on risk-taking and ambiguity aversion. [ABSTRACT FROM AUTHOR]

Abstract: To clarify the neural mechanisms of lexical access and selection of contextually appropriate meanings for ambiguous words, we investigated the spatio-temporal characteristics of neural activities during silent reading and semantic judgment of lexically ambiguous or unambiguous target words that were preceded by semantically related or unrelated words by using magnetoencephalography. The left posterior superior temporal/inferior parietal area and the left anterior middle/inferior temporal area consistently showed a clear context effect, regardless of the ambiguity: the activities for related words were weaker than those for unrelated words. The activities in the left inferior frontal cortex, in contrast, were influenced by ambiguities. From ∼200 to 300 ms, the activities in the left anterior inferior frontal cortex (aIFC) were stronger for ambiguous words than for unambiguous words, regardless of context. The stronger activities in the left aIFC, reflecting an increase in controlled semantic retrieval, indicate that multiple meanings for lexically ambiguous words are accessed irrespective of context. At ∼400 ms, the left posterior inferior frontal cortex (pIFC) showed a clear context effect for unambiguous words but not for ambiguous ones. In addition, the activation in the left pIFC was stronger for related ambiguous words than for related unambiguous ones. These results suggest that in ambiguous words, not only contextually appropriate meanings but also two or more inappropriate meanings would be semantically integrated with a context. We conclude that the left IFC plays an important role in selecting an appropriate meaning from multiple alternatives after the integration of contextual information. [Copyright &y& Elsevier]

Abstract: In an event-related fMRI study, we examined the cortical networks involved in establishing reference during language comprehension. We compared BOLD responses to sentences containing referentially ambiguous pronouns (e.g., “Ronald told Frank that he…”), referentially failing pronouns (e.g., “Rose told Emily that he…”) or coherent pronouns. Referential ambiguity selectively recruited medial prefrontal regions, suggesting that readers engaged in problem-solving to select a unique referent from the discourse model. Referential failure elicited activation increases in brain regions associated with morpho-syntactic processing, and, for those readers who took failing pronouns to refer to unmentioned entities, additional regions associated with elaborative inferencing were observed. The networks activated by these two referential problems did not overlap with the network activated by a standard semantic anomaly. Instead, we observed a double dissociation, in that the systems activated by semantic anomaly are deactivated by referential ambiguity, and vice versa. This inverse coupling may reflect the dynamic recruitment of semantic and episodic processing to resolve semantically or referentially problematic situations. More generally, our findings suggest that neurocognitive accounts of language comprehension need to address not just how we parse a sentence and combine individual word meanings, but also how we determine who''s who and what''s what during language comprehension. [Copyright &y& Elsevier]

Abstract: The meaning of a word usually depends on the context in which it occurs. This study investigated the neural mechanisms involved in computing word meanings that change as a function of syntactic context. Current semantic processing theories suggest that word meanings are retrieved from diverse cortical regions storing sensory–motor and other types of semantic information and are further integrated with context in left inferior frontal gyrus (LIFG). Our fMRI data indicate that brain activity in an area sensitive to motion and action semantics – the posterior middle temporal gyrus (PMTG) – is modulated by a word’s syntactic context. Ambiguous words such as bowl were presented in minimal disambiguating contexts indicating object (the bowl) or action (to bowl) meanings and were compared to low-ambiguity controls. Ambiguous words elicited more activity than low-ambiguity controls in LIFG and various meaning-related areas such as PMTG. Critically, ambiguous words also elicited more activity in to-contexts than the-contexts in PMTG and LIFG, suggesting that contextual integration strengthened the action meaning in both areas. The pattern of results suggests that the activation of lexical information in PMTG was sensitive to contextual disambiguating information and that processing context-dependent meanings may involve interactions between frontal and posterior areas. [Copyright &y& Elsevier]

Abstract: Lexical semantic ambiguity is the phenomenon when a word has multiple meanings (e.g. ‘bank’). The aim of this event-related functional MRI study was to identify those brain areas, which are involved in contextually driven ambiguity resolution. Ambiguous words were selected which have a most frequent, dominant, and less frequent, subordinate meaning. These words were presented in two types of sentences: (1) a sentence congruent with the dominant interpretation and (2) a sentence congruent with the subordinate interpretation. Sentences without ambiguous words served as a control condition. The ambiguous words always occurred early in the sentences and were biased towards one particular meaning by the final word(s) of the sentence; the event at the end of the sentences was modeled. The results indicate that a bilaterally distributed network supports semantic ambiguity comprehension: left (BA 45/44) and right (BA 47) inferior frontal gyri and left (BA 20/37) and right inferior/middle temporal gyri (BA 20). The pattern of activation is most consistent with a scenario in which initially a frequency-based probabilistic choice is made between the alternative meanings, and the meaning is updated when this interpretation does not fit into the final disambiguating context. The neural pattern is consistent with the results of other neuroimaging experiments which manipulated various aspects of integrative and context processing task demands. The presence of a bilateral network is also in line with the lesion and divided visual field literature, but contrary to earlier claims, the two hemispheres appear to play similar roles during semantic ambiguity resolution. [Copyright &y& Elsevier]

Abstract: Affective appraisal often involves processing complex and ambiguous stimuli, such as the mood of a group people. However, affective neuroimaging research often uses individual faces as stimuli when exploring the neural circuitry involved in social appraisal. Results from studies using single face paradigms may not generalize to settings where multiple faces are simultaneously processed. The goal of the current study was to use a novel task that presents groups of affective faces to probe the medial prefrontal cortex (PFC), a region that is critically involved in appraisal of ambiguous affective stimuli, in healthy volunteers. In the current study, 27 subjects performed the Wall of Faces (WOF) task in which multiple matrices of faces were briefly presented during functional MRI. Subjects were asked to decide whether there were more angry or happy faces (emotional decision) or whether there were more male or female faces (gender decision). In each condition, the array contained either an equal (ambiguous trials) or an unequal (unambiguous trials) distribution of one affect or gender. Ambiguous trials relative to unambiguous trials activated regions implicated in conflict monitoring and cognitive control, including the dorsal anterior cingulate cortex (ACC), dorsolateral PFC, and posterior parietal cortex. When comparing ambiguous affective decisions with ambiguous gender decisions, the ventromedial PFC (including the ventral ACC) was significantly more active. This supports the dissociation of the ACC into dorsal cognitive and ventral affective divisions, and suggests that the ventromedial PFC may play a critical role in appraising affective tone in a complex display of multiple human faces. [Copyright &y& Elsevier]

One important issue in neuroimaging research on language is how the brain processes and represents lexical semantics. Past studies with various paradigms reveal that the left inferior prefrontal and mid-superior temporal regions play a crucial role in semantic processing. Those studies, however, typically utilize words having a precise and dominant meaning as stimuli and have not manipulated lexico-semantic ambiguity, a key feature of human language, as an experimental variable. Here, we used a word generation paradigm to examine whether neuroanatomical networks for meaning are modulated by lexical ambiguity. We found that, compared with semantically precise words, semantically ambiguous words were mediated by strong brain activations in the left dorsal–lateral frontal areas, the anterior cingulate, and the right inferior parietal lobe. Semantically precise words, instead, were associated with the left inferior prefrontal and mid-superior temporal sites. These findings indicate that semantic analysis of written words is a dynamic process involving coordination of widely distributed neural subsystems, which are weighted by semantic ambiguity. [Copyright &y& Elsevier]

Relating the meaning of a word to the context in which it is encountered is central to comprehension. We investigated the neural basis of this process. Subjects made decisions based on a semantic property of single nouns. The lack of sentence context created ambiguity, as nouns may have several, unrelated semantic identities. Contrasted with unambiguous decisions about each noun’s sound structure, the semantic task resulted in activity in the left superior frontal gyrus (SFG), activity that was dependent on choice reaction time. This identified the left SFG as an executive component of a distributed cognitive system that relates a word’s meaning to its semantic context to facilitate comprehension. [Copyright &y& Elsevier]

Both self-motion and objects moving in our visual field generate visual motion by displacing images on the retina. Resolving this ambiguity may seem effortless but large-field visual-motion stimuli can yield perceptual rivalry between the real percept of object-motion and the illusory percept of self-motion (vection). We used functional magnetic resonance imaging to record brain activity in human observers exposed to constant-velocity roll-motion. This stimulus induced responses in areas reaching from calcarine to parieto-occipital and to ventral and lateral temporo-occipital cortex and the anterior insula. During vection, early motion-sensitive visual areas and vestibular parieto-insular cortex deactivated, whereas higher-order parieto- and temporo-occipital areas known to respond to optical flow retained identical activity levels. Within this sustained response, these latter areas displayed transient activations in response to each perceptual switch as identified in event-related analyses. Our results thus show that these areas are responsive to the type of visual motion stimulus and highly sensitive to its perceptual bistability. The only region to be more active during perceived self-motion was in, or close to, the cerebellar nodulus. This activation may correspond to the gain increase of torsional optokinetic nystagmus during vection and/or to changes in sensory processing related to the rotational percept. In conclusion, we identified neural correlates of perceiving self-motion from vision alone, i.e., in the absence of confirmatory vestibular or proprioceptive input. These functional properties preserve the organism''s ability to move accurately in its environment by relying on visual cues under conditions when the other spatial senses fail to provide such information. [Copyright &y& Elsevier]

The brain is organized into distinct, flexible networks. Within these networks, cognitive variables such as attention can modulate sensory representations in accordance with moment-to-moment behavioral requirements. These modulations can be studied by varying task demands; however, the tasks employed are often incongruent with the postulated functions of a sensory system, limiting the characterization of the system in relation to natural behaviors. Here we combine domain-specific task manipulations and ultra-high field fMRI to study the nature of top-down modulations. We exploited faces, a visual category underpinned by a complex cortical network, and instructed participants to perform either a stimulus-relevant/domain-specific or a stimulus-irrelevant task in the scanner. We found that 1. perceptual ambiguity (i.e. difficulty of achieving a stable percept) is encoded in top-down modulations from higher-level cortices; 2. the right inferior-temporal lobe is active under challenging conditions and uniquely encodes trial-by-trial variability in face perception. [ABSTRACT FROM AUTHOR]

Homonyms are a critical test case for investigating how the brain resolves ambiguity in language and, more generally, how context influences semantic processing. Previous neuroimaging studies have associated processing of homonyms with greater engagement of regions involved in executive control of semantic processing. However, the precise role of these areas and the involvement of semantic representational regions in homonym comprehension remain elusive. We addressed this by combining univariate and multivariate fMRI analyses of homonym processing. We tested whether multi-voxel activation patterns could discriminate between presentations of the same homonym in different contexts (e.g., bark following tree vs. bark following dog). The ventral anterior temporal lobe, implicated in semantic representation but not previously in homonym comprehension, showed this meaning-specific coding, despite not showing increased mean activation for homonyms. Within inferior frontal gyrus (IFG), a key site for semantic control, there was a dissociation between pars orbitalis, which also showed meaning-specific coding, and pars triangularis, which discriminated more generally between semantically related and unrelated word pairs. IFG effects were goal-dependent, only occurring when the task required semantic decisions, in line with a top-down control function. Finally, posterior middle temporal cortex showed a hybrid pattern of responses, supporting the idea that it acts as an interface between semantic representations and the control system. The study provides new evidence for context-dependent coding in the semantic system and clarifies the role of control regions in processing ambiguity. It also highlights the importance of combining univariate and multivariate neuroimaging data to fully elucidate the role of a brain region in semantic cognition. [ABSTRACT FROM AUTHOR]

Recent accounts of large-scale cortical organisation suggest that the default mode network (DMN) is positioned at the top of a principal gradient, reflecting the separation between heteromodal and unimodal sensory-motor regions in patterns of connectivity and in geodesic distance along the cortical surface (Margulies et al., 2016). This isolation of DMN from external inputs might allow the integration of disparate sources of information that can constrain subsequent cognition. We tested this hypothesis by manipulating the degree to which semantic decisions for ambiguous words (e.g. jam) were constrained by preceding visual cues depicting relevant spatial contexts (e.g. supermarket or road) and/or facial emotions (e.g. happy vs. frustrated). We contrasted (i) the effects of a single preceding cue with a no-cue condition employing scrambled images, and (ii) convergent spatial and emotion cues with single cues. Single cues elicited stronger activation in the multiple demand network relative to no cues, consistent with the requirement to maintain information in working memory. The availability of two convergent cues elicited stronger activation within DMN regions (bilateral angular gyrus, middle temporal gyrus, medial prefrontal cortex, and posterior cingulate), even though behavioural performance was unchanged by cueing – consequently task difficulty is unlikely to account for the observed differences in brain activation. A regions-of-interest analysis along the unimodal-to-heteromodal principal gradient revealed maximal activation for the convergent cue condition at the heteromodal end, corresponding to the DMN. Our findings are consistent with the view that regions of DMN support states of information integration that constrain ongoing cognition and provide a framework for understanding the location of these effects at the heteromodal end of the principal gradient. [ABSTRACT FROM AUTHOR]

Gratitude arises when one is the target of an altruistic decision, particularly when this decision incurs cost to the agent. Here we examined how individuals evaluate others' altruistic decisions under risky (uncertainty with known probabilities) and ambiguous (uncertainty with unknown probabilities) costs and respond with gratitude and reciprocity. Participants played an interactive game in an fMRI scanner in which they would receive painful electric shocks. An anonymous co-player either intentionally (Human conditions) or unintentionally (Computer conditions) decided whether to help the participant reduce half of the pain by undertaking an amount of pain (i.e., cost) with varying level of uncertainty (Certain vs. Risky vs. Ambiguous). Participants could then transfer monetary points to the co-player knowing that the co-player was unaware of this transfer. Behaviorally, monetary allocation and gratitude rating increased as the uncertainty level of cost increased in Human conditions; these effects were reduced in Computer conditions. The effect of cost uncertainty on gratitude was mediated by the perceived kind intention behind the help. FMRI revealed both shared and differential neurocognitive substrates for evaluating the benefactor's altruistic decisions under risk and ambiguity: both were associated with fear- and anxiety-related processes, involving right lateral orbitofrontal cortex and anterior insula; ambiguity additionally recruited mentalizing- and conflict monitoring-related processes, involving dorsal medial prefrontal cortex and dorsal anterior cingulate cortex. These findings underscore the crucial role of social uncertainty perception in the generation of gratitude. • An interactive paradigm is used to elicit gratitude under risky or ambiguous cost. • Perceived kind intention mediates beneficiary's generation of gratitude. • Fear- and anxiety-related processes are implicated in both types of uncertainty. • Mentalizing and conflict monitoring processes are linked with ambiguity processing. [ABSTRACT FROM AUTHOR]