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A low number of individuals show an atypical brain control of language functions that differs from the typical lateralization in the left cerebral hemisphere. In these cases, the neural distribution of other cognitive functions is not fully understood. Although there is a bias towards a mirrored brain organization consistent with the Causal hypothesis, some individuals are found to be exceptions to this rule. However, no study has focused on what happens to the homologous language areas in the right frontal inferior cortex. Using an fMRI-adapted stop-signal task in a healthy non right-handed sample (50 typically lateralized and 36 atypically lateralized for language production), our results show that atypical lateralization is associated with a mirrored brain organization of the inhibitory control network in the left hemisphere: inferior frontal cortex, presupplementary motor area, and subthalamic nucleus. However, the individual analyses revealed a large number of cases with a noteworthy overlap in the inferior frontal gyrus, which shared both inhibitory and language functions. Further analyses showed that atypical lateralization was associated with stronger functional interhemispheric connectivity and larger corpus callosum. Importantly, we did not find task performance differences as a function of lateralization, but there was an association between atypical dominance in the inferior frontal cortex and higher scores on schizotypy and autistic spectrum traits, as well as worse performance on a reading accuracy test. Together, these results partially support the Causal hypothesis of hemispheric specialization and provide further evidence of the link between atypical hemispheric lateralization and increased interhemispheric transfer through the corpus callosum.

Background: Timely identification of the risk of having Major Depressive Disorder (MDD) using the advanced machine learning (ML) approach has been popularized to generate neural indicators of MDD. However, past ML studies have usually employed a comprehensive whole-brain approach, resulting in high computational cost that is hardly affordable in practical and clinical contexts. Methods: In this study, we took an alternative approach by first conducting a meta-analysis to identify brain regions of interest (ROIs) where structural and/or functional alterations had been consistently reported in MDD patients. We then utilized a nonlinear multilayer deep neural network method to evaluate the classification accuracies of MDD patients (N = 41, 29 females) and healthy individuals (N = 20, 12 females) based on the structural volume and resting-state functional connectivity (rsFC) of the ROIs. Results: We found that the ML model based on brain volumes, with the inferior frontal cortex (IFC), amygdala, and the pons receiving the highest weights, achieved higher classification accuracy and sensitivity relative to the model based on rsFC. Limitations: For ethical reasons, people with MDD remained taking antidepressants at the time of the study. Conclusions: Our findings highlight the critical role of the pons-cortico-limbic network in MDD, which is a significant insight for early identification and diagnosis of the illness for timely intervention.

Bilingualism and multilingualism are highly prevalent. Non-invasive brain imaging has been used to study the neural correlates of native and non-native speech and language production, mainly on the lexical and syntactic level. Here, we acquired continuous fast event-related FMRI during visually cued overt production of exclusively German and English vowels and syllables. We analyzed data from 13 university students, native speakers of German and sequential English bilinguals. The production of non-native English sounds was associated with increased activity of the left primary sensorimotor cortex, bilateral cerebellar hemispheres (lobule VI), left inferior frontal gyrus, and left anterior insula compared to native German sounds. The contrast German > English sounds was not statistically significant. Our results emphasize that the production of non-native speech requires additional neural resources already on a basic phonological level in sequential bilinguals. [ABSTRACT FROM AUTHOR]

Humans are capable of acquiring multiple types of information presented in the same information stream. It has been suggested that at least two parallel learning processes are important during learning of sequential patterns—statistical learning and rule‐based learning. Yet, the neurophysiological underpinnings of these parallel learning processes are not fully understood. To differentiate between the simultaneous mechanisms at the single trial level, we apply a temporal EEG signal decomposition approach together with sLORETA source localization method to delineate whether distinct statistical and rule‐based learning codes can be distinguished in EEG data and can be related to distinct functional neuroanatomical structures. We demonstrate that concomitant but distinct aspects of information coded in the N2 time window play a role in these mechanisms: mismatch detection and response control underlie statistical learning and rule‐based learning, respectively, albeit with different levels of time‐sensitivity. Moreover, the effects of the two learning mechanisms in the different temporally decomposed clusters of neural activity also differed from each other in neural sources. Importantly, the right inferior frontal cortex (BA44) was specifically implicated in visuomotor statistical learning, confirming its role in the acquisition of transitional probabilities. In contrast, visuomotor rule‐based learning was associated with the prefrontal gyrus (BA6). The results show how simultaneous learning mechanisms operate at the neurophysiological level and are orchestrated by distinct prefrontal cortical areas. The current findings deepen our understanding on the mechanisms of how humans are capable of learning multiple types of information from the same stimulus stream in a parallel fashion. [ABSTRACT FROM AUTHOR]

Inhibitory control relies on attention, inhibition, and other functions that are integrated across neural networks in an interactive manner. Functional MRI studies have provided excellent spatial mapping of the involved regions. However, finer temporal resolution is needed to capture the underlying neural dynamics and the pattern of their functional contributions. Here, we used anatomically-constrained magnetoencephalography (aMEG) which combines MEG with structural MRI to examine how the spatial (“where”) and temporal (“when”) processing stages and interregional co-oscillations unfold in real time to contribute to inhibitory control. Healthy participants completed a modified Go/NoGo paradigm in which a subset of stimuli was modified to be visually salient (SAL). Compared to the non-modified condition, the SAL manipulation facilitated response withholding on NoGo trials and hindered responding to Go stimuli, reflecting attentional capture effectuated by an orienting response to SAL stimuli. aMEG source estimates indicate SAL stimuli elicited the attentional “circuit breaker” effect through early activity within a right-lateralized network centered around the lateral temporal cortex with additional activity in the pre-supplementary motor area (preSMA) and anterior insula (aINS/FO). Activity of the bilateral inferior frontal cortex responded specifically to inhibitory demands and was generally unaffected by the attentional manipulation. In contrast, early aINS/FO activity was sensitive to stimulus salience while subsequent activity was specific to inhibitory control. Activity estimated to the medial prefrontal cortex including the dorsal anterior cingulate cortex and preSMA reflected an integrative role that was sensitive to both inhibitory and attentional stimulus properties. At the level of neurofunctional networks, neural synchrony in the theta band (4–7 Hz) revealed interactions between principal cortical regions subserving attentional and inhibitory processes. Together, these results underscore the dynamic, integrative processing stages underlying inhibitory control.

Unexpected and thus surprising events are omnipresent and oftentimes require adaptive behavior such as unexpected inhibition or unexpected action. The current theory of unexpected events suggests that such unexpected events just like global stopping recruit a fronto-basal-ganglia network. A global suppressive effect impacting ongoing motor responses and cognition is specifically attributed to the subthalamic nucleus (STN). Previous studies either used separate tasks or presented unexpected, task-unrelated stimuli during response inhibition tasks to relate the neural signature of unexpected events to that of stopping. Here, we aimed to test these predictions using a within task design with identical stimulus material for both unexpected action and unexpected inhibition using functional magnetic resonance imaging (fMRI) for the first time. To this end, 32 healthy human participants of both sexes performed a cue-informed go/nogo task comprising expected and unexpected action and inhibition trials during fMRI. Using conjunction, contrast, and Bayesian analyses, we demonstrate that unexpected action elicited by an unexpected go signal and unexpected inhibition elicited by an unexpected nogo signal recruited the same fronto-basal-ganglia network which is usually assigned to stopping. Furthermore, the stronger the unexpected action-related activity in the STN region was the more detrimental was the effect on response times. The present results thus complement earlier findings and provide direct evidence for the unified theory of unexpected events while ruling out alternative task and novelty effects. [ABSTRACT FROM AUTHOR]

Background: Pitch and duration mismatch negativity (pMMN/dMMN) are related to left Heschl's gyrus gray matter volumes in first-episode schizophrenia (FESz). Previous methods were unable to delineate functional subregions within and outside Heschl's gyrus. The Human Connectome Project multimodal parcellation (HCP-MMP) atlas overcomes this limitation by parcellating these functional subregions. Further, MMN has generators in inferior frontal cortex, and therefore, may be associated with inferior frontal cortex pathology. With the novel use of the HCP-MMP to precisely parcellate auditory and inferior frontal cortex, we investigated relationships between gray matter and pMMN and dMMN in FESz. Methods: pMMN and dMMN were measured at Fz from 27 FESz and 27 matched healthy controls. T1-weighted MRI scans were acquired. The HCP-MMP atlas was applied to individuals, and gray matter volumes were calculated for bilateral auditory and inferior frontal cortex parcels and correlated with MMN. FDR correction was used for multiple comparisons. Results: In FESz only, pMMN was negatively correlated with left medial belt in auditory cortex and area 47L in inferior frontal cortex. Duration MMN negatively correlated with the following auditory parcels: left medial belt, lateral belt, parabelt, TA2, and right A5. Further, dMMN was associated with left area 47L, right area 44, and right area 47L in inferior frontal cortex. Conclusions: The novel approach revealed overlapping and distinct gray matter associations for pMMN and dMMN in auditory and inferior frontal cortex in FESz. Thus, pMMN and dMMN may serve as biomarkers of underlying pathological deficits in both similar and slightly different cortical areas. [ABSTRACT FROM AUTHOR]

Deception scholars have argued that increasing the liar’s cognitive system artificially can produce deception cues. However, if too much load is imposed, the truth tellers’ performance can also be impaired. To address this issue, we designed a veracity task that incorporated a secondary task to increase cognitive load gradually. Also, because deception has been associated with activity in the inferior frontal cortex (IFC), we examined the influence of transcranial direct current stimulation (tDCS) of the IFC on performance. During stimulation, participants truthfully or deceptively indicated whether each of a number of statements shown on screen was true or not. Higher load decreased recall but not general compliance or response times (RTs). Truthful trials yielded higher compliance rates and faster RTs than deceptive trials except for the highest load level. Anodal right stimulation decreased compliance in truthful trials when participants were not overloaded. Truth telling was more vulnerable to cognitive load and tDCS than lying.

Deception scholars have argued that increasing the liar's cognitive system artificially can produce deception cues. However, if too much load is imposed, the truth tellers' performance can also be impaired. To address this issue, we designed a veracity task that incorporated a secondary task to increase cognitive load gradually. Also, because deception has been associated with activity in the inferior frontal cortex (IFC), we examined the influence of transcranial direct current stimulation (tDCS) of the IFC on performance. During stimulation, participants truthfully or deceptively indicated whether each of a number of statements shown on screen was true or not. Higher load decreased recall but not general compliance or response times (RTs). Truthful trials yielded higher compliance rates and faster RTs than deceptive trials except for the highest load level. Anodal right stimulation decreased compliance in truthful trials when participants were not overloaded. Truth telling was more vulnerable to cognitive load and tDCS than lying. [ABSTRACT FROM AUTHOR]

A low number of individuals show an atypical brain control of language functions that differs from the typical lateralization in the left cerebral hemisphere. In these cases, the neural distribution of other cognitive functions is not fully understood. Although there is a bias towards a mirrored brain organization consistent with the Causal hypothesis, some individuals are found to be exceptions to this rule. However, no study has focused on what happens to the homologous language areas in the right frontal inferior cortex. Using an fMRI-adapted stop-signal task in a healthy non right-handed sample (50 typically lateralized and 36 atypically lateralized for language production), our results show that atypical lateralization is associated with a mirrored brain organization of the inhibitory control network in the left hemisphere: inferior frontal cortex, presupplementary motor area, and subthalamic nucleus. However, the individual analyses revealed a large number of cases with a noteworthy overlap in the inferior frontal gyrus, which shared both inhibitory and language functions. Further analyses showed that atypical lateralization was associated with stronger functional interhemispheric connectivity and larger corpus callosum. Importantly, we did not find task performance differences as a function of lateralization, but there was an association between atypical dominance in the inferior frontal cortex and higher scores on schizotypy and autistic spectrum traits, as well as worse performance on a reading accuracy test. Together, these results partially support the Causal hypothesis of hemispheric specialization and provide further evidence of the link between atypical hemispheric lateralization and increased interhemispheric transfer through the corpus callosum., Competing Interests: EV, CC, LM, MP, CA No competing interests declared, (© 2023, Villar-Rodríguez et al.)

Albeit cognitive flexibility is well known to decline in aging, it has not been considered that this ability often requires sequential task control. That is, one may re-use tasks that have previously been abandoned in favor of another task. It is unclear whether sequential cognitive flexibility is affected in aging and what neurophysiological mechanisms and functional neuroanatomical structures are associated with these effects. We examined this question in a system neurophysiological study using EEG and source localization in healthy and elderly adults. We show that elderly people reveal deficient sequential cognitive flexibility. Elderly people encounter increased costs to overcome the inhibition of the lately abandoned task set that becomes relevant again and needs to be re-used. The neurophysiological (EEG) data show that differences in sequential cognitive flexibility between young and elderly people emerge as a consequence of two independent, dysfunctional processes: (i) the ability to suppress task-irrelevant information and (ii) the ability to re-implement a previously abandoned task set during response selection. These independent processes were associated with activation differences in inferior frontal and inferior parietal regions. The study reveals a new facet of cognitive flexibility dysfunctions in healthy elderlies. [ABSTRACT FROM AUTHOR]

Abstract Attention Deficit Hyperactivity Disorder (ADHD) is associated with poor self-control, underpinned by inferior fronto-striatal deficits. We showed previously that 18 ADHD adolescents over 11 runs of 8.5 min of real-time functional magnetic resonance neurofeedback of the right inferior frontal cortex (rIFC) progressively increased activation in 2 regions of the rIFC which was associated with clinical symptom improvement. In this study, we used functional connectivity analyses to investigate whether fMRI-Neurofeedback of rIFC resulted in dynamic functional connectivity changes in underlying neural networks. Whole-brain seed-based functional connectivity analyses were conducted using the two clusters showing progressively increased activation in rIFC as seed regions to test for changes in functional connectivity before and after 11 fMRI-Neurofeedback runs. Furthermore, we tested whether the resulting functional connectivity changes were associated with clinical symptom improvements and whether they were specific to fMRI-Neurofeedback of rIFC when compared to a control group who had to self-regulate another region. rIFC showed increased positive functional connectivity after relative to before fMRI-Neurofeedback with dorsal caudate and anterior cingulate and increased negative functional connectivity with regions of the default mode network (DMN) such as posterior cingulate and precuneus. Furthermore, the functional connectivity changes were correlated with clinical improvements and the functional connectivity and correlation findings were specific to the rIFC-Neurofeedback group. The findings show for the first time that fMRI-Neurofeedback of a typically dysfunctional frontal region in ADHD adolescents leads to strengthening within fronto-cingulo-striatal networks and to weakening of functional connectivity with posterior DMN regions and that this may be underlying clinical improvement. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Reward plays a crucial role in enhancing response inhibition. While it is generally assumed that the process of response inhibition involves attentional capture and the stopping of action, it is unclear whether this reflects a direct impact of reward on response inhibition or rather an indirect mediation via attentional capture. Here, we employed a revised stop-signal task (SST) that separated these two cognitive elements, by including a continue signal that required the same motor response as in go trials, but also attention to a cue, as in stop trials. We first confirmed the engagement of the right inferior frontal gyrus (IFG) during stop and continue trials, both of which required the attentional capture of the task-relevant cue, but only one of which required motor inhibition. The pre-supplementary motor area (pre-SMA) was specifically activated by the contrast of the stop trials with the continue trials. The results indicated that the IFG played an important role in attentional capture by unexpected stimuli, while the pre-SMA was responsible for the direct control of motor inhibition. Behavioral performance of the SST was improved by reward, and moreover, reward induced an increase in IFG activity. In addition, this advantageous reward effect was associated with enhanced connectivity between the anterior cingulate cortex and the IFG. These results indicated that the reward facilitation effect on response inhibition was indirect, occurring via a change in attentional processing. The present data confirm the specific function of the IFG and pre-SMA in response inhibition and provide straightforward evidence that reward can increase attentional capture-related activation in the IFG, which in turn improves the performance of response inhibition. [ABSTRACT FROM AUTHOR]

Abstract Much of human learning emerges as a result of interaction with others. Yet, this interpersonal process has been poorly characterized from a neurophysiological perspective. This study investigated (i) whether Interpersonal Brain Synchronization (IBS) can reliably mark social interactive learning, and specifically (ii) during what kind of interactive behavior. We recorded brain activity from learner-instructor dyads using functional Near-Infrared Spectroscopy (fNIRS) during the acquisition of a music song. We made four fundamental observations. First, during the interactive learning task, brain activity recorded from the bilateral Inferior Frontal Cortex (IFC) synchronized across the learner and the instructor. Second, such IBS was observed in particular when the learner was observing the instructor's vocal behavior and when the learning experience entailed a turn-taking and more active mode of interaction. Third, this specific enhancement of IBS predicted learner's behavioral performance. Fourth, Granger causality analyses further disclosed that the signal recorded from the instructor's brain better predicted that recorded from the learner's brain than vice versa. Together, these results indicate that social interactive learning can be neurophysiologically characterized in terms of IBS. Furthermore, they suggest that the learner's involvement in the learning experience, alongside the instructor's modeling, are key factors driving the alignment of neural processes across learner and instructor. Such alignment impacts upon the real-time acquisition of new information and eventually upon the learning (behavioral) performance. Hence, besides providing a biological characterization of social interactive learning, our results hold relevance for clinical and pedagogical practices. Highlights • fNIRS hyperscanning is performed during social interactive learning. • Interpersonal brain synchronization (IBS) of IFC increases during learning. • IBS is affected by the learners' involvement. • IBS correlates with learners' performance. • IBS may function as a neural alignment across learner and instructor. [ABSTRACT FROM AUTHOR]

Developmental dyslexia is a cognitive disorder characterized by difficulties in linguistic processing. Our purpose is to distinguish subtypes of developmental dyslexia by the level of speech–EEG frequency entrainment (δ: 1–4; β: 12.5–22.5; γ1: 25–35; and γ2: 35–80 Hz) in word/pseudoword auditory discrimination. Depending on the type of disabilities, dyslexics can divide into two subtypes—with less pronounced phonological deficits (NoPhoDys—visual dyslexia) and with more pronounced ones (PhoDys—phonological dyslexia). For correctly recognized stimuli, the δ-entrainment is significantly worse in dyslexic children compared to controls at a level of speech prosody and syllabic analysis. Controls and NoPhoDys show a stronger δ-entrainment in the left-hemispheric auditory cortex (AC), anterior temporal lobe (ATL), frontal, and motor cortices than PhoDys. Dyslexic subgroups concerning normolexics have a deficit of δ-entrainment in the left ATL, inferior frontal gyrus (IFG), and the right AC. PhoDys has higher δ-entrainment in the posterior part of adjacent STS regions than NoPhoDys. Insufficient low-frequency β changes over the IFG, the inferior parietal lobe of PhoDys compared to NoPhoDys correspond to their worse phonological short-term memory. Left-dominant 30 Hz-entrainment for normolexics to phonemic frequencies characterizes the right AC, adjacent regions to superior temporal sulcus of dyslexics. The pronounced 40 Hz-entrainment in PhoDys than the other groups suggest a hearing “reassembly” and a poor phonological working memory. Shifting up to higher-frequency γ-entrainment in the AC of NoPhoDys can lead to verbal memory deficits. Different patterns of cortical reorganization based on the left or right hemisphere lead to differential dyslexic profiles.

This pre-registered experiment sought to uncover the temporal relationship between the inferior frontal cortex (IFC) and the pre-supplementary motor area (pre-SMA) during stopping of an ongoing action. Both regions have previously been highlighted as being central to cognitive control of actions, particularly response inhibition. Here we tested which area is activated first during the stopping process using magnetoencephalography, before assessing the relative chronometry of each region using functionally localized transcranial magnetic stimulation. Both lines of evidence pointed towards simultaneous activity across both regions, suggesting that parallel, mutually interdependent processing may form the cortical basis of stopping. Additional exploratory analysis, however, provided weak evidence in support of previous suggestions that the pre-SMA may provide an ongoing drive of activity to the IFC.

fMRI studies using a region-of-interest approach have revealed that the ventral portion of the left occipito-temporal cortex, which is specialized for orthographic processing of visually presented words (and includes the so-called “visual word form area”, VWFA), is characterized by a posterior-to-anterior gradient of increasing selectivity for words in typically reading adults, adolescents, and children (e.g. Brem et al., 2006, 2009). Similarly, the left inferior frontal cortex (IFC) has been shown to exhibit a medial-to-lateral gradient of print selectivity in typically reading adults (Vinckier et al., 2007). Functional brain imaging studies of dyslexia have reported relative underactivity in left hemisphere occipito-temporal and inferior frontal regions using whole-brain analyses during word processing tasks. Hence, the question arises whether gradient sensitivities in these regions are altered in dyslexia. Indeed, a region-of-interest analysis revealed the gradient-specific functional specialization in the occipito-temporal cortex to be disrupted in dyslexic children (van der Mark et al., 2009). Building on these studies, we here (1) investigate if a word-selective gradient exists in the inferior frontal cortex in addition to the occipito-temporal cortex in normally reading children, (2) compare typically reading with dyslexic children, and (3) examine functional connections between these regions in both groups. We replicated the previously reported anterior-to-posterior gradient of increasing selectivity for words in the left occipito-temporal cortex in typically reading children, and its absence in the dyslexic children. Our novel finding is the detection of a pattern of increasing selectivity for words along the medial-to-lateral axis of the left inferior frontal cortex in typically reading children and evidence of functional connectivity between the most lateral aspect of this area and the anterior aspects of the occipito-temporal cortex. We report absence of an IFC gradient and connectivity between the lateral aspect of the IFC and the anterior occipito-temporal cortex in the dyslexic children. Together, our results provide insights into the source of the anomalies reported in previous studies of dyslexia and add to the growing evidence of an orthographic role of IFC in reading.

Abstract Despite increasing interest in the development of audiovisual speech perception in infancy, the underlying mechanisms and neural processes are still only poorly understood. In addition to regions in temporal cortex associated with speech processing and multimodal integration, such as superior temporal sulcus, left inferior frontal cortex (IFC) has been suggested to be critically involved in mapping information from different modalities during speech perception. To further illuminate the role of IFC during infant language learning and speech perception, the current study examined the processing of auditory, visual and audiovisual speech in 6-month-old infants using functional near-infrared spectroscopy (fNIRS). Our results revealed that infants recruit speech-sensitive regions in frontal cortex including IFC regardless of whether they processed unimodal or multimodal speech. We argue that IFC may play an important role in associating multimodal speech information during the early steps of language learning. [ABSTRACT FROM AUTHOR]

Cortical oscillations phase‐align to the quasi‐rhythmic structure of the speech envelope. This speech–brain entrainment has been reported in two frequency bands, that is both in the theta band (4–8 Hz) and in the delta band (<4 Hz). However, it is not clear if these two phenomena reflect passive synchronization of the auditory cortex to the acoustics of the speech input, or if they reflect higher processes involved in actively parsing speech information. Here, we report two magnetoencephalography experiments in which we contrasted cortical entrainment to natural speech compared to qualitative different control conditions (Experiment 1: amplitude‐modulated white‐noise; Experiment 2: spectrally rotated speech). We computed the coherence between the oscillatory brain activity and the envelope of the auditory stimuli. At the sensor‐level, we observed increased coherence for the delta and the theta band for all conditions in bilateral brain regions. However, only in the delta band (but not theta), speech entrainment was stronger than either of the control auditory inputs. Source reconstruction in the delta band showed that speech, compared to the control conditions, elicited larger coherence in the right superior temporal and left inferior frontal regions. In the theta band, no differential effects were observed for the speech compared to the control conditions. These results suggest that whereas theta entrainment mainly reflects perceptual processing of the auditory signal, delta entrainment involves additional higher‐order computations in the service of language processing. Speech‐specific cortical entrainment was observed in the delta band (<2 Hz) in two separate experiments. No speech‐specific effect emerged in the theta band (4–8 Hz). The results show that delta‐band speech‐specific entrainment recruited right temporal and left inferior frontal regions. [ABSTRACT FROM AUTHOR]

This study investigated local and global changes in the motor network using longitudinal resting-state functional magnetic resonance imaging (rs-fMRI). Motor impairment was measured in 81 stroke patients using Fugl-Meyer assessment on the same day as rs-fMRI acquisition at both 2 weeks and 3 months post-stroke. The relationships between network measures and motor function scores were assessed. With regard to local connectivity, interhemispheric connectivity was noticeably altered at each time point. Interhemispheric connectivity was also related to residual motor function and improvement in motor function. The anterior intraparietal sulcus and other well-known primary and secondary motor-related regions played important roles in motor function. Changes in global connectivity according to stroke type and initial severity were investigated. In global connectivity, interhemispheric connectivity was disrupted at 2 weeks post-stroke regardless of stroke type and initial severity. During the recovery period, interhemispheric connectivity recovered well in patients with hemorrhagic stroke or low severity. In contrast, there were no significant between-group and within-group alterations in intrahemispheric connectivity. Intrahemispheric connectivity of the inferior frontal cortex (IFC) exhibited opposite alterations compared to other connections. There were no differences between groups in IFC connectivity alterations; however, decreasing ipsilesional IFC connectivity and contralesional IFC during recovery were noticeable in patients with mild to moderate impairments and patients with severe impairments, respectively. These results may be helpful in understanding the network changes that occur after stroke and could have important implications for treatment strategy development in future studies. [ABSTRACT FROM AUTHOR]

Risky decision-making under a changing risk level is a complex process involving contextual information. The neural mechanism underlying how sleep deprivation (SD) influences risky decision-making behaviors with a changing risk level has yet to be elucidated. In this study, we used the Balloon Analogue Risk Task (BART) during functional magnetic resonance imaging to investigate the neural correlates of SD-induced changes on decision-making behaviors at different risk levels. Thirty-seven healthy male adults were recruited in this within-subjects, repeat-measure, counterbalanced study. These individuals were examined during a state of rested wakefulness state and after nearly 36 h of total SD. The results showed that SD increased the activation of risk modulation in the left inferior frontal gyrus and were positively correlated with risk-taking propensity after SD. Activation in the ventral striatum and thalamus during cash out was increased, and activation in the middle temporal gyrus after explosion (loss of money) was decreased in sleep-deprived subjects, providing additional evidence for greater risk-taking propensity after SD. These results extend our understanding of the neural mechanism underlying alteration of the risk-taking propensity in sleep-deprived individuals. [ABSTRACT FROM AUTHOR]

Response inhibition mechanisms are mediated via cortical and subcortical networks. At the cortical level, the superior frontal gyrus, including the supplementary motor area (SMA) and inferior frontal areas, is important. There is an ongoing debate about the functional roles of these structures during response inhibition as it is unclear whether these structures process different codes or contents of information during response inhibition. In the current study, we examined this question with a focus on theta frequency oscillations during response inhibition processes. We used a standard Go/Nogo task in a sample of human participants and combined different EEG signal decomposition methods with EEG beamforming approaches. The results suggest that stimulus coding during inhibitory control is attained by oscillations in the upper theta frequency band (∼7 Hz). In contrast, response selection codes during inhibitory control appear to be attained by the lower theta frequency band (∼4 Hz). Importantly, these different codes seem to be processed in distinct functional neuroanatomical structures. Although the SMA may process stimulus codes and response selection codes, the inferior frontal cortex may selectively process response selection codes during inhibitory control. Taken together, the results suggest that different entities within the functional neuroanatomical network associated with response inhibition mechanisms process different kinds of codes during inhibitory control. These codes seem to be reflected by different oscillations within the theta frequency band. Hum Brain Mapp 38:5681-5690, 2017. © 2017 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

In this article, we explore the neural correlates of the general and specific factors assessed by the Life Orientation Test-Revised. These factors have been shown to assess general optimism (GO) and a form of self-enhancement akin to unrealistic optimism (SP). Toward our aim, we used a standardized low-resolution brain electromagnetic tomography (sLORETA), which provides electroencephalographic (EEG) localization measures that are independent of recording reference. Resting-EEG and self-report measures of GO and SP were collected from 51 female undergraduates. EEGs were recorded across 29 scalp sites. Anterior and posterior source alpha asymmetries of cortical activation were obtained by using the sLORETA method. On the basis of previous research findings, ten frontal and six parietal regions of interest (ROIs) were derived. Alpha asymmetry in the posterior cingulate (i.e., BA31) was uniquely associated with GO. In contrast, SP was associated with areas of the inferior frontal gyrus (BA44, BA45) and with the left subcentralis area (BA43). Theoretical and practical implications of the findings are provided and discussed. [ABSTRACT FROM AUTHOR]

Beliefs provide a fundamental cognitive basis for human behavior. But how the brain believes remains a mystery. We investigated the neural underpinnings of believing by scanning healthy adults using functional magnetic resonance imaging when they made yes/no responses to the questions whether they believe or think that a trait adjective describes themselves or a celebrity. We found that, relative to thinking, believing was characterized with better memory of self-related adjectives. Moreover, believing (vs. thinking) was associated with stronger activations in the left anterior insula/inferior frontal cortex, stronger functional connectivity between the medial prefrontal cortex and left occipital cortex during judgments of one's own personality traits, and stronger intrinsic connectivity between the left occipital cortex and the left anterior insula/inferior frontal cortex. Our findings shed new light on the neurocognitive processes that characterize believing as a mental process in healthy adults. [ABSTRACT FROM AUTHOR]

Extensive behavioural evidence has shown that older people have declined ability in facial emotion perception. Recent work has begun to examine the neural mechanism that contribute to this, and potential tools to support emotion perception during aging. The aim of this study was to investigate whether high frequency tRNS applied to the inferior frontal cortex would enhance facial expression perception in older adults. Healthy aged adults (60+ years) were randomly assigned to receive active high-frequency or sham tRNS targeted at bilateral inferior frontal cortices. Each group completed tests of facial identity perception, facial happiness perception and facial anger perception. These tasks were completed before and after stimulation. The results showed that, compared to the sham group, the active tRNS group showed greater gains in performance after stimulation in anger perception (relative to performance before stimulation). The same tRNS stimulation did not significantly change performance on the two other face perception tasks assessing facial identity and facial happiness perception. Examination of how inter-individual variability related to changes in anger perception following tRNS indicated that the degree of performance change in anger perception following active tRNS to inferior frontal cortex was predicted by baseline ability and gender of older adult participants. The findings suggest that high frequency tRNS may be a potential tool to aid anger perception in typical aging, but flag that performance variability and gender may interact with stimulation leading to different outcomes. [ABSTRACT FROM AUTHOR]

Anxious individuals tend to show a negative affective bias in attention that likely reflects reduced executive control, a cognitive function associated with the inferior frontal cortex (IFC), particularly its posterior segment, pars opercularis. Here, we investigated the relations among gray matter volume in the pars opercularis of IFC, trait anxiety, and negative biases in attention, in healthy participants. Sixty-two adults underwent structural magnetic resonance imaging scanning, completed a trait anxiety measure, and performed an Affective Go/No-Go (AGN) task. IFC volumes were extracted using Freesurfer, and negative bias scores were calculated from AGN performance. Trait anxiety correlated negatively with left IFC volume, and positively with the negative bias in reaction time. Furthermore, trait anxiety mediated the negative relation between the IFC volume and the negative bias measure. Overall, the present findings extend previous understanding of the IFC involvement in anxiety at the structural level, and may inform the development of intervention programs targeting anxiety. [ABSTRACT FROM AUTHOR]

This study investigated changes in brain function that occurred over a 7-day behavioral intervention for adults who stutter (AWS). Thirteen AWS received the intervention (AWS+), and 13 AWS did not receive the intervention (AWS-). There were 13 fluent controls (FC-). All participants were scanned before and after the intervention. Whole-brain analysis pre-intervention showed significant differences in task-related brain activation between AWS and FC- in the right inferior frontal cortex (IFC) and left middle temporal cortex, but there were no differences between the two AWS groups. Across the 7-day period of the intervention, AWS+ alone showed a significant increase of brain activation in the left ventral IFC/insula. There were no changes in brain function for the other two groups. Further analysis revealed that the change did not correlate with resting-state functional connectivity (RSFC) that AWS showed in the cerebellum (Lu et al., 2012). However, both changes in task-related brain function and RSFC correlated with changes in speech fluency level. Together, these findings suggest that functional reorganization in a brain region close to the left IFC that shows anomalous function in AWS, occurs after a short-term behavioral intervention for stuttering. [ABSTRACT FROM AUTHOR]

Syntactic competence relies on a left-lateralized network converging on hubs in inferior-frontal and posterior-temporal cortices. We address the question whether anodal transcranial direct current stimulation (a-tDCS) over these hubs can modulate comprehension of sentences, whose syntactic complexity systematically varied along the factors embedding depths and canonicity. Semantic content and length of the sentences were kept identical and forced choice picture matching was required after the full sentence had been presented. We used a single-blind, within-subject, sham-controlled design, applying a-tDCS targeting left posterior tempo-parietal (TP) and left inferior frontal cortex (FC). Stimulation sites were determined by individual neuro-navigation. 20 participants were included of whom 19 entered the analysis. Results were analysed using (generalized) mixed models. In a pilot-experiment in another group of 20 participants we validated the manipulation of syntactic complexity by the two factors embedding depth and argument-order. Reaction times increased and accuracy decreased with higher embedding depth and non-canonical argument order in both experiments. Notably a-tDCS over TP enhanced sentence-to-picture matching, while FC-stimulation showed no consistent effect. Moreover, the analysis disclosed a session effect, indicating improvements of task performance especially regarding speed. We conclude that the posterior 'hub' of the neuronal network affording syntactic analysis represents a 'bottleneck', likely due to working-memory capacity and the challenges of mapping semantic to syntactic information allowing for role assignment. While this does not challenge the role of left inferior-frontal cortex for syntax processing and novel-grammar learning, the application of highly established syntactic rules during sentence comprehension may be considered optimized, thus not augmentable by a-tDCS in the uncompromised network. Anodal transcranial direct current stimulation (a-tDCS) over left temporo-parietal cortex enhances comprehension of complex sentences in uncompromised young speakers. Since a-tDCS over left frontal cortex did not elicit any change, the 'bottleneck' for the understanding of complex sentences seems to be the posterior, temporo-parietal rather than the anterior inferior-frontal 'hub' of language processing. Regarding the attested role of inferior-frontal cortex in syntax processing, we suggest that its function is optimized in competent young speakers, preventing further enhancement by (facilitatory) tDCS. Results shed light on the functional anatomy of syntax processing during sentence comprehension; moreover, they open perspectives for research in the lesioned language network of people with syntactic deficits due to aphasia. [ABSTRACT FROM AUTHOR]

One form of communication that is common in all cultures is people singing together. Singing together reflects an index of cognitive synchronization and cooperation of human brains. Little is known about the neural synchronization mechanism, however. Here, we examined how two brains make one synchronized behavior using cooperated singing/humming between two people and hyperscanning, a new brain scanning technique. Hyperscanning allowed us to observe dynamic cooperation between interacting participants. We used functional near-infrared spectroscopy (fNIRS) to simultaneously record the brain activity of two people while they cooperatively sang or hummed a song in face-to-face (FtF) or face-to-wall (FtW) conditions. By calculating the inter-brain wavelet transform coherence between two interacting brains, we found a significant increase in the neural synchronization of the left inferior frontal cortex (IFC) for cooperative singing or humming regardless of FtF or FtW compared with singing or humming alone. On the other hand, the right IFC showed an increase in neural synchronization for humming only, possibly due to more dependence on musical processing.

Background Response inhibition is a critical executive function, enabling the adaptive control of behavior in a changing environment. The inferior frontal cortex (IFC) is considered to be critical for response inhibition, leading researchers to develop transcranial direct current stimulation (tDCS) montages attempting to target the IFC and improve inhibitory performance. However, conventional tDCS montages produce diffuse current through the brain, making it difficult to establish causality between stimulation of any one given brain region and resulting behavioral changes. Recently, high-definition tDCS (HD-tDCS) methods have been developed to target brain regions with increased focality relative to conventional tDCS. Objective Remarkably few studies have utilized HD-tDCS to improve cognitive task performance, however, and no study has directly compared the behavioral effects of HD-tDCS to conventional tDCS. Methods In the present study, participants received either HD-tDCS or conventional tDCS to the IFC during performance of a response inhibition task (stop-signal task, SST) or a control task (choice reaction time task, CRT). A third group of participants completed the same behavioral protocols, but received tDCS to a control site (mid-occipital cortex). Post-stimulation improvement in SST performance was analyzed as a function of tDCS group and the task performed during stimulation using both conventional and Bayesian parameter estimation analyses. Results Bayesian estimation of the effects of HD- and conventional tDCS to IFC relative to control site stimulation demonstrated enhanced response inhibition for both conditions. No improvements were found after control task (CRT) training in any tDCS condition. Conclusion Results support the use of both HD- and conventional tDCS to the IFC for improving response inhibition, providing empirical evidence that HD-tDCS can be used to facilitate performance on an executive function task. [ABSTRACT FROM AUTHOR]

Pathological narcissism is often characterized by arrogant behavior, a lack of empathy, and willingness to exploit other individuals. Generally, individuals with high levels of narcissism are more likely to suffer mental disorders. However, the brain structural basis of individual pathological narcissism trait among healthy people has not yet been investigated with surface-based morphometry. Thus, in this study, we investigated the relationship between cortical thickness (CT), cortical volume (CV), and individual pathological narcissism in a large healthy sample of 176 college students. Multiple regression was used to analyze the correlation between regional CT, CV, and the total Pathological Narcissism Inventory (PNI) score, adjusting for age, sex, and total intracranial volume. The results showed that the PNI score was significantly negatively associated with CT and CV in the right dorsolateral prefrontal cortex (DLPFC, key region of the central executive network, CEN), which might be associated with impaired emotion regulation processes. Furthermore, the PNI score showed significant negative associations with CV in the right postcentral gyrus, left medial prefrontal cortex (MPFC), and the CT in the right inferior frontal cortex (IFG, overlap with social brain network), which may be related to impairments in social cognition. Together, these findings suggest a unique structural basis for individual differences in pathological narcissism, distributed across different gray matter regions of the social brain network and CEN. [ABSTRACT FROM AUTHOR]

Background: Levodopa-induced dyskinesias are associated with thalamo-cortical disinhibition and frontal area overactivation. Neuroimaging and transcranial magnetic stimulation studies have highlighted the involvement of the right inferior frontal cortex in levodopa-induced dyskinesias.Methods: Using transcranial magnetic stimulation, we tested connectivity between the inferior frontal and contralateral motor cortex in Parkinson's disease patients with and without levodopa-induced dyskinesias compared with age-matched controls. Furthermore, in dyskinetic patients, connectivity between the inferior frontal and contralateral motor cortex was assessed before and after a single session of continuous theta-burst stimulation applied over the inferior frontal cortex.Results: Dyskinetic patients showed abnormal facilitatory connectivity between the inferior frontal and motor cortex when compared with the nondyskinetic group. Continuous theta-burst stimulation over the inferior frontal cortex eliminated such facilitatory connectivity and decreased the levodopa-induced dyskinesias that was induced by a supramaximal dose of levodopa.Conclusion: In dyskinetic patients, a weaker inhibitory cortico-cortical interaction between the inferior frontal and contralateral motor cortex could be involved in levodopa-induced dyskinesias and restored by continuous theta-burst stimulation over the inferior frontal cortex. © 2016 Movement Disorder Society. [ABSTRACT FROM AUTHOR]

People can communicate by using hand actions, e.g., signs. Understanding communicative actions requires that the observer knows that the actor has an intention to communicate and the meanings of the actions. Here, we investigated how this prior knowledge affects processing of observed actions. We used functional MRI to determine changes in action processing when non-signers were told that the observed actions are communicative (i.e., signs) and learned the meanings of half of the actions. Processing of hand actions activated the left and right inferior frontal gyrus (IFG, BA 44 and 45) when the communicative intention of the actor was known, even when the meanings of the actions remained unknown. These regions were not active when the observers did not know about the communicative nature of the hand actions. These findings suggest that the left and right IFG play a role in understanding the intention of the actor, but do not process visuospatial features of the communicative actions. Knowing the meanings of the hand actions further enhanced activity in the anterior part of the IFG (BA 45), the inferior parietal lobule and posterior inferior and middle temporal gyri in the left hemisphere. These left-hemisphere language regions could provide a link between meanings and observed actions. In sum, the findings provide evidence for the segregation of the networks involved in the neural processing of visuospatial features of communicative hand actions and those involved in understanding the actor’s intention and the meanings of the actions. [ABSTRACT FROM AUTHOR]

Background: Parkinson's disease is primarily a disorder of response initiation characterized by an excessive motor inhibition, whereas levodopa-induced dyskinesias are clearly a clinical expression of disinhibition of movements.Objective: That levodopa-induced dyskinesias are linked to dysfunctions of inhibitory brain network has recently been proposed, but no investigation of behavioral performance during action inhibition task in these patients has been published.Methods: Twenty-four Parkinson's disease patients with or without levodopa-induced dyskinesias tested on or off their medications underwent functional magnetic resonance imaging investigation during the execution of a stop-signal inhibition task. In particular, we were interested in evaluating the neural correlates of stop-related conditions: StopInhibit task (in which patients had to successfully inhibit their responses) and StopRespond task (Stop trials with erroneous button press). Both tasks were compared against Go trials.Results: Levodopa intake in dyskinetic patients tended to worsen inhibitory control during the StopInhibit task, while significantly affecting the ability to monitor motor responses when patients failed to stop (StopRespond task). Functional analysis showed that, during the StopInhibit task, dyskinetic patients were characterized by decreased activity of the right inferior frontal cortex after levodopa intake, whereas patients without dyskinesias showed a reverse effect. A similar group × levodopa interaction effect was detected in the medial frontal cortex during the execution of the StopRespond task, in which dyskinetic patients showed increased activity after dopaminergic therapyConclusions: Our study demonstrated that levodopa intake in dyskinetic patients tends to alter the functioning of some parts of the neural network involved in motor inhibition. [ABSTRACT FROM AUTHOR]

Maladaptive plasticity can be defined as behavioral loss or even development of disease symptoms resulting from aberrant plasticity changes in the human brain. Hyperkinetic movement disorders, either in the neurological or psychiatric realms, have been associated with maladaptive neural plasticity that can be expressed by functional changes such as an increase in transmitter release, receptor regulation and synaptic plasticity or anatomical modifications such as axonal regeneration, sprouting, synaptogenesis and neurogenesis. Recent evidence from human and animal models provided support to the hypothesis that these phenomena likely depend upon altered dopamine turnover induced by long-term drug treatment. However, it is still unclear how and where these altered mechanisms of cortical plasticity may be localized. The current article will provide an up-to-date overview of these issues together with some reflections on future studies in the field, particularly focusing on two specific disorders (levodopa-induced dyskinesias in Parkinson’s disease patients and tardive dyskinesias in schizophrenic patients) where the modern neuroimaging approaches have recently provided new fundamental insights.

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. [ABSTRACT FROM AUTHOR]