Brain regions that show repetition suppression and enhancement: A meta‐analysis of 137 neuroimaging experiments

Repetition suppression and enhancement refer to the reduction and increase in the neural responses for repeated rather than novel stimuli, respectively. This study provides a meta‐analysis of the effects of repetition suppression and enhancement, restricting the data used to that involving fMRI/PET, visual stimulus presentation, and healthy participants. The major findings were as follows. First, the global topography of the repetition suppression effects was strikingly similar to that of the “subsequent memory” effects, indicating that the mechanism for repetition suppression is the reduced engagement of an encoding system. The lateral frontal cortex effects involved the frontoparietal control network regions anteriorly and the dorsal attention network regions posteriorly. The left fusiform cortex effects predominantly involved the dorsal attention network regions, whereas the right fusiform cortex effects mainly involved the visual network regions. Second, the category‐specific meta‐analyses and their comparisons indicated that most parts of the alleged category‐specific regions showed repetition suppression for more than one stimulus category. In this regard, these regions may not be “dedicated cortical modules,” but are more likely parts of multiple overlapping large‐scale maps of simple features. Finally, the global topography of the repetition enhancement effects was similar to that of the “retrieval success” effects, suggesting that the mechanism for repetition enhancement is voluntary or involuntary explicit retrieval during an implicit memory task. Taken together, these results clarify the network affiliations of the regions showing reliable repetition suppression and enhancement effects and contribute to the theoretical interpretations of the local and global topography of these two effects. Hum Brain Mapp 38:1894–1913, 2017. © 2017 Wiley Periodicals, Inc.     

Implicitly strengthened task‐irrelevant stimulus‐response associations modulate cognitive control: Evidence from an fMRI study

The dynamics of cognitive control have been investigated by the proportion congruency effect. However, the theory that this effect is due to attentional modulation has been challenged by contingency learning accounts. This raises the question of how the cognitive control system operates during and after increasing the strength of task‐irrelevant stimulus‐response (S‐R) associations. We employed a novel paradigm that elicits positive and reversed Simon effects via task rule manipulations, and combined it with a between subjects proportion congruency manipulation. The pattern of enhancement and reversal of the positive and reversed Simon effects across conditions suggested that participants used strengthened task‐irrelevant S‐R associations to predict responses. Functional neuroimaging identified proportion congruency effects that interacted with task S‐R associations, showing greater activity when strengthened task‐irrelevant S‐R associations conflicted with task‐defined S‐R associations in frontoparietal regions, including bilateral superior parietal lobule (SPL) and dorsal premotor cortex (dPMC), presupplementary motor area/anterior midcingulate cortex (Pre‐SMA/aMCC), and left dorsolateral prefrontal cortex (DLPFC). These results suggest that the aMCC and DLPFC shifted to responding mainly to the conflict induced by the strengthened irrelevant S‐R associations. The SPL and dPMC might represent the strengthened irrelevant S‐R associations. Hum Brain Mapp 37:756–772, 2016. © 2015 Wiley Periodicals, Inc.     

Toward systems neuroscience in mild cognitive impairment and Alzheimer's disease: A meta‐analysis of 75 fMRI studies

Most of the previous task functional magnetic resonance imaging (fMRI) studies found abnormalities in distributed brain regions in mild cognitive impairment (MCI) and Alzheimer's disease (AD), and few studies investigated the brain network dysfunction from the system level. In this meta‐analysis, we aimed to examine brain network dysfunction in MCI and AD. We systematically searched task‐based fMRI studies in MCI and AD published between January 1990 and January 2014. Activation likelihood estimation meta‐analyses were conducted to compare the significant group differences in brain activation, the significant voxels were overlaid onto seven referenced neuronal cortical networks derived from the resting‐state fMRI data of 1,000 healthy participants. Thirty‐nine task‐based fMRI studies (697 MCI patients and 628 healthy controls) were included in MCI‐related meta‐analysis while 36 task‐based fMRI studies (421 AD patients and 512 healthy controls) were included in AD‐related meta‐analysis. The meta‐analytic results revealed that MCI and AD showed abnormal regional brain activation as well as large‐scale brain networks. MCI patients showed hypoactivation in default, frontoparietal, and visual networks relative to healthy controls, whereas AD‐related hypoactivation mainly located in visual, default, and ventral attention networks relative to healthy controls. Both MCI‐related and AD‐related hyperactivation fell in frontoparietal, ventral attention, default, and somatomotor networks relative to healthy controls. MCI and AD presented different pathological while shared similar compensatory large‐scale networks in fulfilling the cognitive tasks. These system‐level findings are helpful to link the fundamental declines of cognitive tasks to brain networks in MCI and AD. Hum Brain Mapp 36:1217–1232, 2015. © 2014 Wiley Periodicals, Inc.     

Auditory and visual connectivity gradients in frontoparietal cortex

A frontoparietal network of brain regions is often implicated in both auditory and visual information processing. Although it is possible that the same set of multimodal regions subserves both modalities, there is increasing evidence that there is a differentiation of sensory function within frontoparietal cortex. Magnetic resonance imaging (MRI) in humans was used to investigate whether different frontoparietal regions showed intrinsic biases in connectivity with visual or auditory modalities. Structural connectivity was assessed with diffusion tractography and functional connectivity was tested using functional MRI. A dorsal–ventral gradient of function was observed, where connectivity with visual cortex dominates dorsal frontal and parietal connections, while connectivity with auditory cortex dominates ventral frontal and parietal regions. A gradient was also observed along the posterior–anterior axis, although in opposite directions in prefrontal and parietal cortices. The results suggest that the location of neural activity within frontoparietal cortex may be influenced by these intrinsic biases toward visual and auditory processing. Thus, the location of activity in frontoparietal cortex may be influenced as much by stimulus modality as the cognitive demands of a task. It was concluded that stimulus modality was spatially encoded throughout frontal and parietal cortices, and was speculated that such an arrangement allows for top–down modulation of modality‐specific information to occur within higher‐order cortex. This could provide a potentially faster and more efficient pathway by which top–down selection between sensory modalities could occur, by constraining modulations to within frontal and parietal regions, rather than long‐range connections to sensory cortices. Hum Brain Mapp 38:255–270, 2017. © 2016 Wiley Periodicals, Inc.     

Intrinsic limbic and paralimbic networks are associated with criminal psychopathy

Background: Psychopathy is a personality disorder associated with impairments in decision‐making, empathy, and impulsivity. Recent brain imaging studies suggest that psychopathy is associated with abnormalities in limbic/paralimbic brain regions. To date, no studies have examined functional brain connectivity measures using independent component analyses (ICA) in adults with psychopathy. Here, we test hypotheses regarding paralimbic connectivity in adult incarcerated individuals stratified by psychopathy scores. Methods: One hundred and two prison inmates were rated using the Hare Psychopathy Checklist‐Revised (PCL‐R). FMRI data were collected while subjects performed an auditory target detection “oddball” task. FMRI data were analyzed using group ICA to identify functional networks responding to the oddball task correlating with psychopathy scores. Results: Components demonstrating significant correlations with psychopathy included a default mode network, a frontoparietal component, and a visual/posterior cingulate component. Modulation trends correlated strongly with factor 2 (impulsivity) and total PCL‐R scores in the frontoparietal and visual/posterior cingulate networks, and with factor 1 (affective) scores within the default mode network. The posterior cingulate region factored significantly in the modulation trends observed. Conclusion: Consistent with the hypothesis of limbic/paralimbic abnormalities associated with psychopathy, modulation trends correlated strongly with PCL‐R scores. There is strong evidence to implicate the posterior cingulate in aberrant functional connectivity associated with the manifestation of psychopathic symptoms. Future investigations comparing functional trends associated with the posterior cingulate in psychopathic subjects may provide further insight into the manifestation of this disorder. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals Inc.     

ALE meta‐analysis reveals dissociable networks for affective and discriminative aspects of touch

Emotionally‐laden tactile stimulation—such as a caress on the skin or the feel of velvet—may represent a functionally distinct domain of touch, underpinned by specific cortical pathways. In order to determine whether, and to what extent, cortical functional neuroanatomy supports a distinction between affective and discriminative touch, an activation likelihood estimate (ALE) meta‐analysis was performed. This meta‐analysis statistically mapped reported functional magnetic resonance imaging (fMRI) activations from 17 published affective touch studies in which tactile stimulation was associated with positive subjective evaluation (n = 291, 34 experimental contrasts). A separate ALE meta‐analysis mapped regions most likely to be activated by tactile stimulation during detection and discrimination tasks (n = 1,075, 91 experimental contrasts). These meta‐analyses revealed dissociable regions for affective and discriminative touch, with posterior insula (PI) more likely to be activated for affective touch, and primary somatosensory cortices (SI) more likely to be activated for discriminative touch. Secondary somatosensory cortex had a high likelihood of engagement by both affective and discriminative touch. Further, meta‐analytic connectivity (MCAM) analyses investigated network‐level co‐activation likelihoods independent of task or stimulus, across a range of domains and paradigms. Affective‐related PI and discriminative‐related SI regions co‐activated with different networks, implicated in dissociable functions, but sharing somatosensory co‐activations. Taken together, these meta‐analytic findings suggest that affective and discriminative touch are dissociable both on the regional and network levels. However, their degree of shared activation likelihood in somatosensory cortices indicates that this dissociation reflects functional biases within tactile processing networks, rather than functionally and anatomically distinct pathways. Hum Brain Mapp 37:1308‐1320, 2016. © 2016 Wiley Periodicals, Inc.     

Spatially dynamic recurrent information flow across long‐range dorsal motor network encodes selective motor goals

Performing voluntary movements involves many regions of the brain, but it is unknown how they work together to plan and execute specific movements. We recorded high‐resolution ultra‐high‐field blood‐oxygen‐level‐dependent signal during a cued ankle‐dorsiflexion task. The spatiotemporal dynamics and the patterns of task‐relevant information flow across the dorsal motor network were investigated. We show that task‐relevant information appears and decays earlier in the higher order areas of the dorsal motor network then in the primary motor cortex. Furthermore, the results show that task‐relevant information is encoded in general initially, and then selective goals are subsequently encoded in specifics subregions across the network. Importantly, the patterns of recurrent information flow across the network vary across different subregions depending on the goal. Recurrent information flow was observed across all higher order areas of the dorsal motor network in the subregions encoding for the current goal. In contrast, only the top–down information flow from the supplementary motor cortex to the frontoparietal regions, with weakened recurrent information flow between the frontoparietal regions and bottom–up information flow from the frontoparietal regions to the supplementary cortex were observed in the subregions encoding for the opposing goal. We conclude that selective motor goal encoding and execution rely on goal‐dependent differences in subregional recurrent information flow patterns across the long‐range dorsal motor network areas that exhibit graded functional specialization.     

The effects of methylphenidate on whole brain intrinsic functional connectivity

Methylphenidate (MPH) is an indirect dopaminergic and noradrenergic agonist that is used to treat attention deficit hyperactivity disorder and that has shown therapeutic potential in neuropsychiatric diseases such as depression, dementia, and Parkinson's disease. While effects of MPH on task‐induced brain activation have been investigated, little is known about how MPH influences the resting brain. To investigate the effects of 40 mg of oral MPH on intrinsic functional connectivity, we used resting state fMRI in 54 healthy male subjects in a double‐blind, randomized, placebo‐controlled study. Functional connectivity analysis employing ICA revealed seven resting state networks (RSN) of interest. Connectivity strength between the dorsal attention network and the thalamus was increased after MPH intake. Other RSN located in association cortex areas, such as the left and right frontoparietal networks and the executive control network, showed MPH‐induced connectivity increase to sensory‐motor and visual cortex regions and connectivity decrease to cortical and subcortical components of cortico‐striato‐thalamo‐cortical circuits (CST). RSN located in sensory‐motor cortex areas showed the opposite pattern with MPH‐induced connectivity increase to CST components and connectivity decrease to sensory‐motor and visual cortex regions. Our results provide evidence that MPH does not only alter intrinsic connectivity between brain areas involved in sustained attention, but that it also induces significant changes in the cortico‐cortical and cortico‐subcortical connectivity of many other cognitive and sensory‐motor RSN. Hum Brain Mapp 35:5379–5388, 2014. © 2014 Wiley Periodicals, Inc.     

Differential brain mechanisms for processing distracting information in task‐relevant and ‐irrelevant dimensions in visual search

A crucial function of our goal‐directed behavior is to select task‐relevant targets among distractor stimuli, some of which may share properties with the target and thus compete for attentional selection. Here, by applying functional magnetic resonance imaging (fMRI) to a visual search task in which a target was embedded in an array of distractors that were homogeneous or heterogeneous along the task‐relevant (orientation or form) and/or task‐irrelevant (color) dimensions, we demonstrate that for both (orientation) feature search and (form) conjunction search, the fusiform gyrus is involved in processing the task‐irrelevant color information, while the bilateral frontal eye fields (FEF), the cortex along the left intraparietal sulcus (IPS), and the left junction of intraparietal and transverse occipital sulci (IPTO) are involved in processing task‐relevant distracting information, especially for target‐absent trials. Moreover, in conjunction (but not in feature) search, activity in these frontoparietal regions is affected by stimulus heterogeneity along the task‐irrelevant dimension: heterogeneity of the task‐irrelevant information increases the activity in these regions only when the task‐relevant information is homogeneous, not when it is heterogeneous. These findings suggest that differential neural mechanisms are involved in processing task‐relevant and task‐irrelevant dimensions of the searched‐for objects. In addition, they show that the top‐down task set plays a dominant role in determining whether or not task‐irrelevant information can affect the processing of the task‐relevant dimension in the frontoparietal regions.     

Differences in theta coherence between spatial and nonspatial attention using intracranial electroencephalographic signals in humans

A number of previous studies revealed the importance of the frontoparietal network for attention and preparatory top‐down control. Here, we investigated the theta (7–9 Hz) coherence of the right frontoparietal networks to explore the differences in connectivity changes for the right frontoparietal regions during spatial attention (i.e., attention to a specific location rather than a specific feature) and nonspatial attention (i.e., attention to a specific feature rather than a specific location) tasks. The theta coherence in both tasks was primarily maintained at a preparatory state, decreases after stimulus onset, and recovers to the level of the preparatory state after the response time. However, the theta coherence of the frontoparietal network during spatial attention was immediately maintained after cue‐onset, whereas for the case of nonspatial attention, it was immediately decreased after cue‐onset. In addition, the connectivity of the right frontoparietal network, including the middle frontal gyrus and superior parietal lobe, were significantly higher for spatial attention rather than for nonspatial attention, suggesting that the dorsal parts of right frontoparietal network are more engaged in spatial‐specific attention from the preparatory state. These findings also suggest that these two attention systems involve the use of different regional connectivity patterns, not only in the cognitive state, but in the preparatory state as well.     

Mapping the spatiotemporal dynamics of processing task‐relevant and task‐irrelevant sound feature changes using concurrent EEG‐fMRI

The cortical processing of changes in auditory input involves auditory sensory regions as well as different frontoparietal brain networks. The spatiotemporal dynamics of the activation spread across these networks has, however, not been investigated in detail so far. We here approached this issue using concurrent functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), providing us with simultaneous information on both the spatial and temporal patterns of change‐related activity. We applied an auditory stimulus categorization task with switching categorization rules, allowing to analyze change‐related responses as a function of the changing sound feature (pitch or duration) and the task relevance of the change. Our data show the successive progression of change‐related activity from regions involved in early change detection to the ventral and dorsal attention networks, and finally the central executive network. While early change detection was found to recruit feature‐specific networks involving auditory sensory but also frontal and parietal brain regions, the later spread of activity across the frontoparietal attention and executive networks was largely independent of the changing sound feature, suggesting the existence of a general feature‐independent processing pathway of change‐related information. Task relevance did not modulate early auditory sensory processing, but was mainly found to affect processing in frontal brain regions. Hum Brain Mapp 37:3400–3416, 2016. © 2016 Wiley Periodicals, Inc.     

Strong rightward lateralization of the dorsal attentional network in left‐handers with right sighting‐eye: An evolutionary advantage

Hemispheric lateralization for spatial attention and its relationships with manual preference strength and eye preference were studied in a sample of 293 healthy individuals balanced for manual preference. Functional magnetic resonance imaging was used to map this large sample while performing visually guided saccadic eye movements. This activated a bilateral distributed cortico‐subcortical network in which dorsal and ventral attentional/saccadic pathways elicited rightward asymmetrical activation depending on manual preference strength and sighting eye. While the ventral pathway showed a strong rightward asymmetry irrespective of both manual preference strength and eye preference, the dorsal frontoparietal network showed a robust rightward asymmetry in strongly left‐handers, even more pronounced in left‐handed subjects with a right sighting‐eye. Our findings brings support to the hypothesis that the origin of the rightward hemispheric dominance for spatial attention may have a manipulo‐spatial origin neither perceptual nor motor per se but rather reflecting a mechanism by which a spatial context is mapped onto the perceptual and motor activities, including the exploration of the spatial environment with eyes and hands. Within this context, strongly left‐handers with a right sighting‐eye may benefit from the advantage of having the same right hemispheric control of their dominant hand and visuospatial attention processing. We suggest that this phenomenon explains why left‐handed right sighting‐eye athletes can outperform their competitors in sporting duels and that the prehistoric and historical constancy of the left‐handers ratio over the general population may relate in part on the hemispheric specialization of spatial attention. Hum Brain Mapp 36:1151–1164, 2015. © 2014 Wiley Periodicals, Inc.     

Neural correlates underlying the attentional spotlight in human parietal cortex independent of task difficulty

Changes in the size of the attentional focus and task difficulty often co‐vary. Nevertheless, the neural processes underlying the attentional spotlight process and task difficulty are likely to differ from each other. To differentiate between the two, we parametrically varied the size of the attentional focus in a novel behavioral paradigm while keeping visual processing difficulty either constant or not. A behavioral control experiment proved that the present behavioral paradigm could indeed effectively manipulate the size of the attentional focus per se, rather than affecting purely perceptual processes or surface processing. Imaging results showed that neural activity in a dorsal frontoparietal network, including right superior parietal cortex (SPL), was positively correlated with the size of the attentional spotlight, irrespective of whether task difficulty was constant or varied across different sizes of attentional focus. In contrast, neural activity in the ventral frontoparietal network, including the right inferior parietal cortex (IPL), was positively correlated with increasing task difficulty. Data suggest that sub‐regions in parietal cortex are differentially involved in the attentional spotlight process and task difficulty: while SPL was involved in the attentional spotlight process independent of task difficulty, IPL was involved in the effect of task difficulty independent of the attentional spotlight process. Hum Brain Mapp 38:4996–5018, 2017. © 2017 Wiley Periodicals, Inc.     

Automatic detection of violations of statistical regularities in the periphery is affected by the focus of spatial attention: A visual mismatch negativity study

We investigated the effect of spatial attention on an event‐related potential signature of automatic detection of violations of statistical regularities, namely, the visual mismatch negativity (vMMN). To vary the task‐field and the location of vMMN‐related stimulation, in the attentional field the stimuli of a tracking task with a steady and a moving (target) bar were presented. The target stimuli of the task appeared either relatively close or far from a passive (task‐irrelevant) oddball or equiprobable sequence at the lower part of the screen. Stimuli of the oddball sequence were shapes tilted either 45° (standard, p = 0.8) or 135° (deviant, p = 0.2), while the equiprobable sequence consisted of additional three shapes with identical number of lines to the oddball stimuli. Deviant stimuli in close proximity to a continuously attended field elicited larger vMMN than similar stimuli farther away from the stimulus field. In the condition with a smaller distance between the field of the tracking task and the vMMN‐related field, the deviant stimuli and the vMMN was followed by a posterior positivity. According to these results, spatial attention modulates vMMN and is capable of initiating further processing of the deviant stimuli.     

Disrupted functional connectivity of cerebellar default network areas in attention‐deficit/hyperactivity disorder

Attention‐deficit/hyperactivity disorder (ADHD) is increasingly understood as a disorder of spontaneous brain‐network interactions. The default mode network (DMN), implicated in ADHD‐linked behaviors including mind‐wandering and attentional fluctuations, has been shown to exhibit abnormal spontaneous functional connectivity (FC) within‐network and with other networks (salience, dorsal attention and frontoparietal) in ADHD. Although the cerebellum has been implicated in the pathophysiology of ADHD, it remains unknown whether cerebellar areas of the DMN (CerDMN) exhibit altered FC with cortical networks in ADHD. Here, 23 adults with ADHD and 23 age‐, IQ‐, and sex‐matched controls underwent resting state fMRI. The mean time series of CerDMN areas was extracted, and FC with the whole brain was calculated. Whole‐brain between‐group differences in FC were assessed. Additionally, relationships between inattention and individual differences in FC were assessed for between‐group interactions. In ADHD, CerDMN areas showed positive FC (in contrast to average FC in the negative direction in controls) with widespread regions of salience, dorsal attention and sensorimotor networks. ADHD individuals also exhibited higher FC (more positive correlation) of CerDMN areas with frontoparietal and visual network regions. Within the control group, but not in ADHD, participants with higher inattention had higher FC between CerDMN and regions in the visual and dorsal attention networks. This work provides novel evidence of impaired CerDMN coupling with cortical networks in ADHD and highlights a role of cerebro‐cerebellar interactions in cognitive function. These data provide support for the potential targeting of CerDMN areas for therapeutic interventions in ADHD. Hum Brain Mapp 36:3373–3386, 2015. © 2015 Wiley Periodicals, Inc.     

Where is the “where” in the brain? A meta‐analysis of neuroimaging studies on spatial cognition

Spatial representations are processed in the service of several different cognitive functions. The present study capitalizes on the Activation Likelihood Estimation (ALE) method of meta‐analysis to identify: (a) the shared neural activations among spatial functions to reveal the “core” network of spatial processing; (b) the specific neural activations associated with each of these functions. Following PRISMA guidelines, a total of 133 fMRI and PET studies were included in the meta‐analysis. The overall analysis showed that the core network of spatial processing comprises regions that are symmetrically distributed on both hemispheres and that include dorsal frontoparietal regions, presupplementary motor area, anterior insula, and frontal operculum. The specific analyses revealed the brain regions that are selectively recruited for each spatial function, such as the right temporoparietal junction for shift of spatial attention, the right parahippocampal gyrus, and the retrosplenial cortex for navigation and spatial long‐term memory. The findings are integrated within a systematic review of the neuroimaging literature and a new neurocognitive model of spatial cognition is proposed.     

Functional connectivity at rest is sensitive to individual differences in executive function: A network analysis

Graph theory provides a means to understand the nature of network characteristics and connectivity between specific brain regions. Here it was used to investigate whether the network characteristics of the brain at rest are associated with three dimensions thought to underlie individual differences in executive function (EF)—common EF, shifting‐specific EF, and updating‐specific EF (Miyake and Friedman [2012]). To do so, both an a priori analysis focused mainly on select frontoparietal regions previously linked to individual differences in EF as well as a whole‐brain analysis were performed. The findings indicated that individual differences in each of the three dimensions of EF were associated with specific patterns of resting‐state connectivity both in a priori and other brain regions. More specifically, higher common EF was associated with greater integrative (i.e., more hublike) connectivity of cuneus and supplementary motor area but less integrative function of lateral frontal nodes and left temporal lobe nodes. Higher shifting‐specific EF was associated with more hublike motor‐related nodes and cingulo‐opercular nodes. Higher updating‐specific EF was associated with less hublike lateral and medial frontoparietal nodes. In general, these results suggested that higher ability in each of these three dimensions of EF was not solely characterized by the connectivity characteristics of frontoparietal regions. The pattern was complicated in that higher EF was associated with the connectivity profile of nodes outside of the traditional frontoparietal network, as well as with less hublike or centrality characteristics of some nodes within the frontoparietal network. Hum Brain Mapp 37:2959–2975, 2016. © 2016 Wiley Periodicals, Inc.     

Emotion perception and executive control interact in the salience network during emotionally charged working memory processing

Processing of emotional stimuli can either hinder or facilitate ongoing working memory (WM); however, the neural basis of these effects remains largely unknown. Here we examined the neural mechanisms of these paradoxical effects by implementing a novel emotional WM task in an fMRI study. Twenty‐five young healthy participants performed an N‐back task with fearful and neutral faces as stimuli. Participants made more errors when performing 0‐back task with fearful versus neutral faces, whereas they made fewer errors when performing 2‐back task with fearful versus neutral faces. These emotional impairment and enhancement on behavioral performance paralleled significant interactions in distributed regions in the salience network including anterior insula (AI) and dorsal cingulate cortex (dACC), as well as in emotion perception network including amygdala and temporal‐occipital association cortex (TOC). The dorsal AI (dAI) and dACC were more activated when comparing fearful with neutral faces in 0‐back task. Contrarily, dAI showed reduced activation, while TOC and amygdala showed stronger responses to fearful as compared to neutral faces in the 2‐back task. These findings provide direct neural evidence to the emerging dual competition model suggesting that the salience network plays a critical role in mediating interaction between emotion perception and executive control when facing ever‐changing behavioral demands. Hum Brain Mapp 35:5606–5616, 2014. © 2014 Wiley Periodicals, Inc.     

Somatosensory working memory performance in humans depends on both engagement and disengagement of regions in a distributed network

Successful working memory (WM) requires the engagement of relevant brain areas but possibly also the disengagement of irrelevant areas. We used magnetoencephalography (MEG) to elucidate the temporal dynamics of areas involved in a somatosensory WM task. We found an increase in gamma band activity in the primary and secondary somatosensory areas during encoding and retention, respectively. This was accompanied by an increase of alpha band activity over task‐irrelevant regions including posterior and ipsilateral somatosensory cortex. Importantly, the alpha band increase was strongest during successful WM performance. Furthermore, we found frontal gamma band activity that correlated both with behavioral performance and the alpha band increase. We suggest that somatosensory gamma band activity reflects maintenance and attention‐related components of WM operations, whereas alpha band activity reflects frontally controlled disengagement of task‐irrelevant regions. Our results demonstrate that resource allocation involving the engagement of task‐relevant and disengagement of task‐irrelevant regions is needed for optimal task execution. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.     

Contextual factors multiplex to control multisensory processes

This study analyzed high‐density event‐related potentials (ERPs) within an electrical neuroimaging framework to provide insights regarding the interaction between multisensory processes and stimulus probabilities. Specifically, we identified the spatiotemporal brain mechanisms by which the proportion of temporally congruent and task‐irrelevant auditory information influences stimulus processing during a visual duration discrimination task. The spatial position (top/bottom) of the visual stimulus was indicative of how frequently the visual and auditory stimuli would be congruent in their duration (i.e., context of congruence). Stronger influences of irrelevant sound were observed when contexts associated with a high proportion of auditory‐visual congruence repeated and also when contexts associated with a low proportion of congruence switched. Context of congruence and context transition resulted in weaker brain responses at 228 to 257 ms poststimulus to conditions giving rise to larger behavioral cross‐modal interactions. Importantly, a control oddball task revealed that both congruent and incongruent audiovisual stimuli triggered equivalent non‐linear multisensory interactions when congruence was not a relevant dimension. Collectively, these results are well explained by statistical learning, which links a particular context (here: a spatial location) with a certain level of top‐down attentional control that further modulates cross‐modal interactions based on whether a particular context repeated or changed. The current findings shed new light on the importance of context‐based control over multisensory processing, whose influences multiplex across finer and broader time scales. Hum Brain Mapp 37:273–288, 2016. © 2015 Wiley Periodicals, Inc.