IFG Activity Research Articles

Aesthetic evaluation of body movements shaped by embodied and arts experience: Insights from behaviour and fNIRS

Aesthetic appreciation of full-body movements is likely shaped by our cumulative bodily experiences, yet most of the extant literature in this domain has focused on expertise and familiarity. We ran two experiments exploring individual differences in embodied experience and experience with the arts: In Study 1, we explored how participants’ (n = 41) abilities to learn a choreography shaped their aesthetic perceptions while viewing learned vs. unknown movements, using functional near-infrared spectroscopy (fNIRS) to measure cortical activation over the Action Observation Network (i.e., inferior frontal gyrus [IFG], inferior parietal lobule, middle temporal gyrus [MTG]). Study 1 demonstrated that embodied experience enhanced ratings of enjoyment, familiarity, and reproducibility of movements, and that individual differences in participants’ performance of the learned choreography were not associated with aesthetic ratings, but rather cortical activation in IFG and right MTG while viewing learned choreography. In Study 2, we combined the behavioural data from Study 1 with data from additional participants (total n = 141) to examine the relationship between arts experience and aesthetic perceptions of movements robustly. Study 2 revealed that previous arts and sports experience correlated with aesthetic judgements of familiarity and reproducibility of movements. Our findings highlight the relevance of examining individual experiences to fill theoretical gaps in our understanding of action aesthetics.

Microstructural properties of attention-related white matter tracts are associated with the renewal effect of extinction

The tendency to show the renewal effect of extinction appears as an intra-individually stable, reproducible processing strategy associated with differential patterns of BOLD activation in hippocampus, iFG and vmPFC, as well as differential resting-state functional connectivity between prefrontal regions and the dorsal attention network. Also, pharmacological modulations of the noradrenergic system that influence attentional processing have partially different effects upon individuals with (REN) and without (NoREN) a propensity for renewal. However, it is as yet unknown whether REN and NoREN individuals differ regarding microstructural properties in attention-related white matter (WM) regions, and whether such differences are related to noradrenergic processing. In this diffusion tensor imaging (DTI) analysis we investigated the relation between microstructural properties of attention-related WM tracts and ABA renewal propensity, under conditions of noradrenergic stimulation by means of the noradrenergic reuptake inhibitor atomoxetine, compared to placebo.Fractional anisotropy (FA) was higher in participants with noradrenergic stimulation (ATO) compared to placebo (PLAC), the effect was predominantly left-lateralized and based on the comparison of ATO REN and PLAC REN participants. In REN participants of both treatment groups, FA in several WM tracts showed a positive correlation with the ABA renewal level, suggesting higher renewal levels were associated with higher microstructural integrity. These findings point towards a relation between microstructural properties of attention-related WM tracts and the propensity for renewal that is not specifically dependent on noradrenergic processing.

Sentence superiority in the reading brain

When a sequence of written words is briefly presented and participants are asked to identify just one word at a post-cued location, then word identification accuracy is higher when the word is presented in a grammatically correct sequence compared with an ungrammatical sequence. This sentence superiority effect has been reported in several behavioral studies and two EEG investigations. Taken together, the results of these studies support the hypothesis that the sentence superiority effect is primarily driven by rapid access to a sentence-level representation via partial word identification processes that operate in parallel over several words. Here we used MEG to examine the neural structures involved in this early stage of written sentence processing, and to further specify the timing of the different processes involved. Source activities over time showed grammatical vs. ungrammatical differences first in the left inferior frontal gyrus (IFG: 321–406 ms), then the left anterior temporal lobe (ATL: 466–531 ms), and finally in both left IFG (549–602 ms) and left posterior superior temporal gyrus (pSTG: 553–622 ms). We interpret the early IFG activity as reflecting the rapid bottom-up activation of sentence-level representations, including syntax, enabled by partly parallel word processing. Subsequent activity in ATL and pSTG is thought to reflect the constraints imposed by such sentence-level representations on on-going word-based semantic activation (ATL), and the subsequent development of a more detailed sentence-level representation (pSTG). These results provide further support for a cascaded interactive-activation account of sentence reading.

The neurobiological map of theory of mind and pragmatic communication in autism

ABSTRACT Children with autism often have difficulty with Theory of Mind (ToM), the ability to infer mental states, and pragmatic skills, the contextual use of language. Neuroimaging research suggests ToM and pragmatic skills overlap, as the ability to understand another’s mental state is a prerequisite to interpersonal communication. To our knowledge, no study in the last decade has examined this overlap further. To assess the emerging consensus across neuroimaging studies of ToM and pragmatic skills in autism, we used coordinate-based activation likelihood estimation (ALE) analysis of 35 functional magnetic resonance imaging (MRI) studies (13 pragmatic skills, 22 ToM), resulting in a meta-analysis of 1,295 participants (647 autistic, 648 non-autistic) aged 7 to 49 years. Group difference analysis revealed decreased left inferior frontal gyrus (LIFG) activation in autistic participants during pragmatic skills tasks. For ToM tasks, we found reduced anterior cingulate cortex (ACC), medial prefrontal cortex (MPFC), and temporoparietal junction (TPJ) activation in autistic participants. Collectively, both ToM and pragmatic tasks showed activation in IFG and superior temporal gyrus (STG) and a reduction in left hemispheric activation in autistic participants. Overall, the findings underscore the cognitive and neural processing similarities between ToM and pragmatic skills, and their underlying neurobiological differences in autism.

The Neural Processes in Food Decision-making and their Effect on Daily Diet Management in Successful and Unsuccessful Restrained Eaters

This study aimed to explore the neural mechanisms underlying food decision making in unsuccessful restrained eaters (US-REs) and successful restrained eaters (S-REs). During a functional magnetic resonance imaging scan, participants were required to choose between pairs of high- and low-calorie foods under the following conditions: the congruent condition (choose between high- and low-calorie foods with the same level of tastiness) and incongruent condition (choose between high-calorie foods tastier than the corresponding low-calorie foods). Subsequently, the participants’ diets were monitored for one week. The behavioral results showed that US-REs (n = 28) chose more high-calorie foods than S-REs (n = 26); in contrast, S-REs spent more time in choosing for the incongruent than the congruent condition. The fMRI results found that US-REs exhibited more activity in reward regions (caudate and thalamus) than S-REs in the congruent condition. In the incongruent condition, S-REs showed stronger functional connectivity between the conflict-monitoring region (anterior cingulate cortex) and inhibitory-control regions (inferior frontal gyrus [IFG] and medial frontal gyrus) than US-REs. In both the conditions, increased activation of the insula, putamen, middle frontal gyrus, and IFG could predict increased food intake among US-REs in the following week. Furthermore, in both the conditions, increased IFG activation could predict decreased food cravings among S-REs during the following week. Our results suggest that US-REs have a strong reward response to food. Compared to US-REs, S-REs are more guided more by the goal of weight control, and exhibit strong functional connections between the conflict-monitoring and inhibitory-control regions. Therefore, eating enjoyment and weight-control goals influence restrained eating in daily life.

Air-conducted ultrasound below the hearing threshold elicits functional changes in the cognitive control network.

Air-conducted ultrasound (> 17.8 kHz; US) is produced by an increasing number of technical devices in our daily environment. While several studies indicate that exposure to US in public spaces can lead to subjective symptoms such as 'annoyance' or 'difficulties in concentration', the effects of US on brain activity are poorly understood. In the present study, individual hearing thresholds (HT) for sounds in the US frequency spectrum were assessed in 21 normal-hearing participants. The effects of US were then investigated by means of functional magnetic resonance imaging (fMRI). 15 of these participants underwent three resting-state acquisitions, two with a 21.5 kHz tone presented monaurally at 5 dB above (ATC) and 10 dB below (BTC) the HT and one without auditory stimulation (NTC), as well as three runs of an n-back working memory task involving similar stimulus conditions (n-ATC, n-BTC, n-NTC). Comparing data gathered during n-NTC vs. fixation, we found that task performance was associated with the recruitment of regions within the cognitive control network, including prefrontal and parietal areas as well as the cerebellum. Direct contrasts of the two stimulus conditions (n-ATC & n-BTC) vs. n-NTC showed no significant differences in brain activity, irrespective of whether a whole-brain or a region of interest approach with primary auditory cortex as the seed was used. Likewise, no differences were found when the resting-state runs were compared. However, contrast analysis (n-BTC vs. n-ATC) revealed a strong activation in bilateral inferior frontal gyrus (IFG, triangular part) only when US was presented below the HT (p < 0.001, cluster > 30). In addition, IFG activation was also associated with faster reaction times during n-BTC (p = 0.033) as well as with verbal reports obtained after resting-state, i.e., the more unpleasant sound was perceived during BTC vs. ATC, the higher activation in bilateral IFG was and vice versa (p = 0.003). While this study provides no evidence for activation of primary auditory cortex in response to audible US (even though participants heard the sounds), it indicates that US can lead to changes in the cognitive control network and affect cognitive performance only when presented below the HT. Activation of bilateral IFG could reflect an increase in cognitive demand when focusing on task performance in the presence of slightly unpleasant and/or distracting US that may not be fully controllable by attentional mechanisms.

A prospective investigation of youth alcohol experimentation and reward responsivity in the ABCD study.

RationaleGreater risk-taking behaviors, such as alcohol experimentation, are associated with different patterns of brain functioning in regions implicated in reward (nucleus accumbens, NA) and cognitive control (inferior frontal gyrus, IFG). These neural features have been observed in youth with greater risk-taking tendencies prior to substance use initiation, suggesting NA-IFG disruption may serve as an early marker for subsequent substance use disorders. Prospective studies are needed to determine if NA-IFG neural disruption predicts future substance use in school-age children, including those with minimal use of alcohol (e.g., sipping). The present large-sample prospective study sought to use machine learning to: (1) examine alcohol sipping at ages 9, 10 as a potential behavioral indicator of concurrent underlying altered neural responsivity to reward, and (2) determine if alcohol sipping and NA-IFG activation at ages 9, 10 can be used to predict which youth reported increased alcohol use at ages 11, 12. Additionally, low-level alcohol use and brain functioning at ages 9, 10 were examined as predictors of substance use and brain functioning at ages 11, 12.Design and methodsThis project used data from the baseline (Time 1) and two-year follow-up (Time 2) assessments of the Adolescent Brain Cognitive Development (ABCD) Study (Release 3.0). Support Vector Machine (SVM) learning determined if: (1) NA-IFG neural activity could correctly identify youth who reported alcohol sipping at Time 1 (n = 7409, mean age = 119.34 months, SD = 7.53; 50.27% female), and (2) NA-IFG and alcohol sipping frequency at Time 1 could correctly identify youth who reported drinking alcohol at Time 2 (n = 4000, mean age = 143.25 months, SD = 7.63; 47.53% female). Linear regression was also used to examine the relationship between alcohol sipping and NA-IFG activity at Time 1 and substance use and NA-IFG activity at Time 2. Data were also examined to characterize the environmental context in which youth first tried sips of alcohol (e.g., with or without parental permission, as part of a religious experience).ResultsApproximately 24% of the sample reported having tried sips of alcohol by ages 9, 10. On average, youth reported trying sips of alcohol 4.87 times (SD = 23.19) with age of first sip occurring at 7.36 years old (SD = 1.91). The first SVM model classified youth according to alcohol sipping status at Time 1 no better than chance with an accuracy of 0.35 (balanced accuracy = 0.52, sensitivity = 0.24, specificity = 0.80). The second SVM model classified youth according to alcohol drinking status at Time 2 with an accuracy of 0.76 (balanced accuracy = 0.56, sensitivity = 0.21, specificity = 0.91). Linear regression demonstrated that frequency of alcohol sipping at Time 1 predicted frequency of alcohol use at Time 2 (p < 0.001, adjusted R2 = 0.075). Alcohol sipping at Time 1 was not linearly associated with NA or IFG activity at Time 2 (all ps > 0.05), and NA activity at Time 1 and Time 2 were not related (all ps > 0.05). Activity in the three subsections of the IFG at Time 1 predicted activity in those same regions at Time 2 (all ps < 0.02).Conclusions and implicationsEarly sips of alcohol appear to predict alcohol use in early adolescence. Findings do not provide strong evidence for minimal early alcohol use (sipping) as a behavioral marker of underlying alterations in NA-IFG neural responsivity to reward. Improving our understanding of the neural and behavioral factors that indicate a greater propensity for future substance use is crucial for identifying at-risk youth and potential targets for preventative efforts.

NMDA receptor-mediated processing in inferior frontal gyrus facilitates acquisition and extinction learning and strengthens renewal

While the renewal effect of extinction is considered to be invoked by attention to context during the extinction phase, there is also evidence that processing during initial learning (acquisition) may be important for later renewal. A noradrenergic agonist and a dopaminergic antagonist, administered before acquisition, did not affect renewal, however, the effects of NMDAergic neurotransmission in this regard are as yet unknown.In a previous study, administration of a single dose of the NMDA agonist d-cycloserine (DCS) before extinction learning facilitated extinction in the context of acquisition (AAA), but had no effect upon renewal. In the present fMRI study, DCS was administered prior to the initial acquisition of a predictive learning task, in order to investigate whether NMDA receptor (NMDAR) stimulation at this timepoint will modulate overall learning as well as the level of renewal, while increasing activation in the extinction- and renewal-relevant brain regions of inferior frontal gyrus (iFG) and hippocampus (HC).DCS facilitated acquisition, as well as extinction learning in the context of acquisition (AAA), and raised the level of ABA renewal. While BOLD activation during acquisition did not differ between treatment groups, activation in bilateral iFG showed a double dissociation during processing of AAA extinction trials, with DCS-mediated higher activation in right iFG and deactivation in left iFG. In contrast, placebo showed higher activation in left iFG and deactivation in right iFG. During the test (recall) phase, left iFG and right anterior hippocampus activation was increased in DCS participants who showed renewal, with activation in this region correlating with the ABA renewal level.The results demonstrate that NMDA receptor stimulation can facilitate both initial learning and extinction of associations, and in this way has an impact upon the resultant level of renewal. In particular NMDAergic processing in iFG appears relevant for the facilitation of AAA extinction and ABA recall in the test phase.

Automatic and effortful control of interference in working memory can be distinguished by unique behavioral and functional brain representations

Goal-irrelevant information in working memory (WM) may enter the focus of attention (FOA) during a task and cause proactive interference (PI). In the current study we used fMRI to test several hypotheses concerning the boundary conditions of PI in WM using a modified verbal 2-back task. Temporal distance between item and lure presentation was manipulated to evaluate potential differences among hypothesized states of FOA, short-term memory and long-term memory. PI was present for the most proximal 3-back lures but dissipated with lure distance along with increased activation in brain regions critical for memory recollection, such as right prefrontal cortex, parietal cortex, and hippocampus. Reduced PI and less IFG activation were also observed after repeated item presentation, supporting the notion that a rehearsed encoding of item-context information reduces the need for interference control. Moreover, a trial-by-trial approach revealed activity in ACC, insula, IFG, and parietal cortex with increasing lure trial interference regardless of distance. The current results are first evidence for an observable transition of cognitive control, to include MTL regions involved in recalling task-relevant information from outside the FOA when resolving PI in WM.

Transdiagnostic alterations in neural emotion regulation circuits \u2013 neural substrates of cognitive reappraisal in patients with depression and post-traumatic stress disorder

BackgroundImpaired cognitive reappraisal, associated with the social functioning and well-being of patients affected by mood or anxiety disorders, is characterized by distinct neural activation patterns across clinical populations. To date, studies dedicated to identifying common and distinct neural activation profiles need to be clarified. The aim of the present study was to investigate transdiagnostic differences and commonalities in brain activation patterns during reappraisal-mediated downregulation of emotions.MethodsCognitive reappraisal of negative images was contrasted with maintaining emotions during a control viewing condition. Brain activation in 35 patients with major depressive disorder (MDD), 20 patients with post-traumatic stress disorder (PTSD), and 34 healthy controls (HC) during cognitive reappraisal was compared. Moreover, the neural circuitry of emotion regulation in these clinical populations was examined using seed-to-voxel and voxel-to-voxel functional connectivity analyses.ResultsWhole-brain fMRI analyses showed less right-lateralized activation of the inferior, middle, and superior frontal gyrus during cognitive reappraisal compared to viewing of negative images in MDD and PTSD patients compared to HCs. Right IFG activation was negatively correlated with the severity of anxiety and depressive symptomatology. In addition, increased seed-to-voxel connectivity of the right IFG as well as increased voxel-to-voxel connectivity was observed in PTSD patients compared to HCs and MDD patients.ConclusionsFMRI results therefore suggested a common deficit of depression and anxiety symptomatology reflected by reduced activation in right IFG during cognitive reappraisal as well as diagnosis specific effects in patients with PTSD based on seed-to-voxel and voxel-to-voxel connectivity showing an overactive and hyperconnected salience network. Findings highlight the role of transdiagnostic research to identify disorder specific brain patterns as well as patterns common across disorders.

Effect of Exoskeleton-Assisted Rehabilitation Over Prefrontal Cortex in Multiple Sclerosis Patients: A Neuroimaging Pilot Study

Application of a passive and fully articulated exoskeleton, called Human Body Posturizer (HBP), has been demonstrated to improve mobility, response accuracy and ambulation in multiple sclerosis (MS) patients. By using functional magnetic imaging (fMRI) during a visuomotor discrimination task, we performed a pilot study to evaluate the effect of HBP over the neural correlates of motor and cognitive functions which are typically impaired in MS patients. Specifically, we tested the effect of a 6-week multidisciplinary rehabilitation intervention on two groups of MS patients: a control group who followed a standard physiotherapeutic rehabilitation protocol, and an experimental group who used the HBP during physical exercises in addition to the standard protocol. We found that, after treatment, the experimental group exhibited a significant lower activity (as compared to the control group) in the inferior frontal gyrus. This post-treatment activity reduction can be explained as a retour to a normal range, being the amount of iFg activity observed in the experimental patients very similar to that observed in healthy subjects. These findings indicate that the use of HBP during rehabilitation intervention normalizes the prefrontal activity, mitigating the cortical hyperactivity associated to MS.

The DA-antagonist Tiapride affects context-related extinction learning in a predictive learning task, but not initial forming of associations, or renewal

Renewal describes the recovery of an extinguished response if the contexts of extinction and recall differ, highlighting the context dependency of extinction. Studies demonstrated dopaminergic (DA) signalling to be important for context-related extinction learning with and without a fear component. In a previous study in humans, administration of the dopamine D2/D3 antagonist tiapride prior to extinction impaired extinction learning in a novel, but not a familiar context, without affecting renewal. In a further study, context processing during initial acquisition of associations was shown to be related to renewal. In this human fMRI study we investigated the potential role of DA signalling during this initial conditioning for the learning process and for renewal. While tiapride, administered prior to the start of learning, did not affect initial acquisition and renewal, extinction learning in a novel context was impaired, associated with reduced BOLD activation in vmPFC, left iFG and ACC – regions mediating response inhibition and selection from competing options using contextual information. Thus, different timepoints of administration of tiapride (before initial conditioning or extinction) had largely similar effects upon extinction and renewal. In addition, retrieval of previously acquired associations was impaired, pointing towards weaker association forming during acquisition.Conceivably, effects of the DA blockade are associated with the challenge present in the respective task rather than the administration timepoint: the cognitive flexibility required for forming a new inhibitory association that includes a novel element clearly requires DA processing, while initial forming of associations, or of inhibitory associations without a new element, apparently rely less on the proper function of the DA system.

Reciprocal relations between reading skill and the neural basis of phonological awareness in 7- to 9-year-old children

By using a longitudinal design and functional magnetic resonance imaging (fMRI), our previous study (Wang et al., 2020) found a scaffolding effect of early phonological processing in the superior temporal gyrus (STG) in 6-year-old children on later behavioral reading skill in 7.5-year-old children. Other than this previous study, nothing is known about longitudinal change in the bidirectional relation between reading skill and phonological processing in the brain. To fill this gap, in the current study, we used the same experimental paradigm as in Wang et al. (2020) to measure children's reading skill and brain activity during an auditory phonological awareness task, but with children who were 7.5 years old at Time 1 (T1) and about 1.5 years later when they were 9 years old at Time 2 (T2). The phonological awareness task included both small grain (i.e., onset) and large grain (i.e., rhyme) conditions. In a univariate analysis, we found that better reading skill at T1 predicted lower brain activation in IFG at T2 for onset processing after controlling for brain activation and non-verbal IQ at T1. This suggests that early reading ability reduces the effort of phonemic access, thus supporting the refinement hypothesis. When using general psychophysiological interaction (gPPI), we found that higher functional connectivity from IFG to STG for rhyme processing at T1 predicted better reading skill at T2 after controlling for reading skill and non-verbal IQ at T1. This suggests that the early effectiveness of accessing rhyme representations scaffolds reading acquisition. As both results did not survive multiple comparison corrections, replication of these findings is needed. However, both findings are consistent with prior studies demonstrating that phonological access in the frontal lobe becomes important in older elementary school readers. Moreover, the refinement effect for onsets is consistent with the hypothesis that learning to read allows for better access of small grain phonology, and the scaffolding effect for rhymes supports the idea that reading progresses to larger grain orthography-to-phonology mapping in older skilled readers. The current study, along with our previous study on younger children, indicates that the development of reading skill is associated with (1) the early importance of the quality of the phonological representations to later access of these representations, and (2) early importance of small grain sizes to later development of large grain ones.

Functional connectivity in the developing language network in 4-year-old children predicts future reading ability.

Understanding how pre-literate children's language abilities and neural function relate to future reading ability is important for identifying children who may be at-risk for reading problems. Pre-literate children are already proficient users of spoken language and their developing brain networks for language become highly overlapping with brain networks that emerge during literacy acquisition. In the present longitudinal study, we examined language abilities, and neural activation and connectivity within the language network in pre-literate children (mean age=4.2years). We tested how language abilities, brain activation, and connectivity predict children's reading abilities 1year later (mean age=5.2years). At Time 1, children (n=37) participated in a functional near infrared spectroscopy (fNIRS) experiment of speech processing (listening to words and pseudowords) and completed a standardized battery of language and cognitive assessments. At Time 2, children (n=28) completed standardized reading assessments. Using psychophysiological interaction (PPI) analyses, we observed significant connectivity between the left IFG and right STG in pre-literate children, which was modulated by task (i.e., listening to words). Neural activation in left IFG and STG and increased task-modulated connectivity between the left IFG and right STG was predictive of multiple reading outcomes. Increased connectivity was associated later with increased reading ability.

Audio-visual combination of syllables involves time-sensitive dynamics following from fusion failure

In face-to-face communication, audio-visual (AV) stimuli can be fused, combined or perceived as mismatching. While the left superior temporal sulcus (STS) is presumably the locus of AV integration, the process leading to combination is unknown. Based on previous modelling work, we hypothesize that combination results from a complex dynamic originating in a failure to integrate AV inputs, followed by a reconstruction of the most plausible AV sequence. In two different behavioural tasks and one MEG experiment, we observed that combination is more time demanding than fusion. Using time-/source-resolved human MEG analyses with linear and dynamic causal models, we show that both fusion and combination involve early detection of AV incongruence in the STS, whereas combination is further associated with enhanced activity of AV asynchrony-sensitive regions (auditory and inferior frontal cortices). Based on neural signal decoding, we finally show that only combination can be decoded from the IFG activity and that combination is decoded later than fusion in the STS. These results indicate that the AV speech integration outcome primarily depends on whether the STS converges or not onto an existing multimodal syllable representation, and that combination results from subsequent temporal processing, presumably the off-line re-ordering of incongruent AV stimuli.

Left Inferior Frontal Gyrus Participates in Mediating the Renewal Effect Irrespective of Context Salience.

The renewal effect of extinction demonstrates the context-dependency of extinction learning. It is defined as the recovery of an extinguished response occurring when the contexts of extinction and recall differ. Behavioral studies showed that modulating context relevance can strengthen context-specific responses. In our fMRI study, we investigated to what extent a modulation of context salience can alter renewal levels and provide additional information about the neural basis for renewal. In a within-subjects design, participants completed two sessions of an associative learning task in randomized order. In the salient condition (SAL), a context was presented alone at the start of each trial, before being presented together with the stimulus. The regular condition (REG) contained no context-alone phase. In about one-third of participants (SWITCH), the context salience modulation significantly increased renewal rates in the SAL compared to the REG condition. The other participants showed either renewal (REN) or no renewal (NoREN) in both conditions. The modulation did not significantly affect learning performance during the initial forming of associations or extinction learning. In the SWITCH group, activation in left opercular inferior frontal gyrus (iFG) during the recall phase was associated with a renewal effect, together with activity in the bilateral posterior hippocampus and ventromedial prefrontal cortex (vmPFC). Also during the extinction phase, left opercular iFG activation was higher in groups exhibiting renewal in recall, irrespective of the context salience modulation. Besides confirming the participation of vmPFC in extinction recall, our findings provide novel insights regarding an as yet undetected, potentially important role for renewal-supporting processes in left iFG during extinction learning and recall, which are presumably based on the region’s proposed function of evaluating competing response options under conditions of ambiguity.

The impact of stimulus modality on the processing of conflicting sensory information during response inhibition

Response inhibition is a central aspect of cognitive control. Usually, response inhibition is examined using information from a single sensory modality. Yet, evidence suggests that conflicts between information from different modalities affect response inhibition. It is, however, crucial to consider that there are modality differences in the efficiency to trigger response inhibition that may also modulate the impact of conflicts between different sensory modalities. In the current study, we compared an auditory–tactile to an auditory–visual Go/NO-GO task. We recorded EEG data and performed signal decomposition and source localization. On the behavioral level, we show stronger interference effects in the visual than the tactile modality. Despite sensory processes were experimentally varied, temporally decomposed EEG data show that response selection mechanisms are associated with these effects and not the sensory processing stage. These modulations of response selection processes occur in the temporo-parietal junction (TPJ, BA40) and inferior frontal structures (IFG, BA47). The smaller activity in the TPJ during auditory–tactile, compared to auditory–visual conflicts suggests that task representations are less affected by interfering auditory information when the tactile modality informs response inhibition processes. This also explains why less intense braking processes (reflected by IFG activity) are still able to maintain a reasonable response inhibition performance level. It can be concluded that the tactile and visual domains do not only differ in regard to their efficiency to trigger response inhibition processes but also in their susceptibility to interference while informing inhibitory control. Clinical implications are discussed.

Effects of Noradrenergic Stimulation Upon Context-Related Extinction Learning Performance and BOLD Activation in Hippocampus and Prefrontal Cortex Differ Between Participants Showing and Not Showing Renewal.

While the neural structures mediating context-related renewal of extinction are well established, the neurotransmitter systems processing renewal remain elusive. Noradrenergic stimulation before extinction improved learning, but did not alter renewal. Since context processing already during initial conditioning can influence renewal, in this fMRI study we investigated how noradrenergic stimulation by a single dose of atomoxetine (ATO) before initial acquisition of a context-related predictive-learning task affects subsequent learning and renewal in humans. ATO participants showing contextual renewal (REN) exhibited a selective extinction learning deficit compared to placebo (PLAC) and ATO participants lacking renewal (ATO NoREN), probably owing to formation of more stable associations during acquisition. New learning and retrieval during the extinction phase as well as initial acquisition were unimpaired. In ATO REN, higher activation in right inferior frontal gyrus (iFG) during acquisition may have supported the formation of more stable associations, while reduced activation in hippocampus and left iFG during extinction was associated with impaired context encoding and response inhibition. During recall, ATO REN showed reduced overall context-dependent renewal associated with higher activation in medial PFC and right hippocampus. The results demonstrate the importance of noradrenergic processing in inferior frontal cortex and hippocampus for human extinction learning, but not necessarily initial conditioning. Since an identical atomoxetine treatment evoked diverging blood-oxygen level dependent (BOLD) activation patterns in REN and NoREN participants, the effect is presumably related to the participants’ preferred processing strategies that may have recruited differentially interconnected networks in which noradrenergic stimulation produced diverging consequences. In the ATO REN group, probably an additive effect of their preferred processing strategy, which pre-activated the noradrenergic system, and the experimental treatment caused a shift beyond the optimal working range of the noradrenergic system, thus modulating BOLD activation in a way that impaired extinction learning and recall.

Decreased cortical and subcortical response to inhibition control after sleep deprivation.

The effects of sleep deprivation (SD) on the neural substrates of inhibition control are poorly understood. Here we used functional magnetic resonance imaging to examine the effects of 24h of SD on cerebral activation during a stop-signal task in 20 normal young subjects. Behaviorally, subjects showed significantly delayed stop-signal reaction time (SSRT) following SD. In addition, reduced cerebral activation was found in the "stopping network" (including the inferior frontal gyrus [IFG], supplementary motor area, subthalamic nucleus [STN] and insula) and vision-related regions (occipital cortex, lingual gyrus and fusiform gyrus) after SD. These findings support the hypothesis that task-related activation in prefrontal cortex is particularly vulnerable to SD. After rested wakefulness (RW), significant negative correlations were found between SSRT and cerebral activation in left IFG, right hippocampus, right lingual gyrus, left STN and bilateral fusiform gyrus, with activation in left IFG making the most contribution. After SD, significant negative correlations were found between SSRT and activation in right middle frontal cortex, right IFG and left lingual gyrus, with the activation in right IFG making the most contribution. Furthermore, we observed significant interaction effects of state (SD or RW) with activation in bilateral IFG, left STN and left lingual gyrus on SSRT. In conclusion, sleep deprivation is associated with the deficits in inhibition-related neural activation and the altered correlation between SSRT and cerebral activation, especially in the bilateral IFG, left STN and left lingual gyrus.

Transcranial direct current stimulation (tDCS) targeting the left inferior frontal gyrus: Effects on creativity across cultures

ABSTRACTAlthough evidence points to the existence of cultural differences in creativity, the mechanisms that underlie these differences are largely unknown. The twofold model of creativity posits two recursive stages: a generation phase and an evaluation phase. Considering that recent studies suggest that the left inferior frontal gyrus) L-IFG(may inhibit creativity during the evaluation phase, we hypothesized that manipulating IFG activity would affect participants’ level of creativity. We further predicted that the IFG may be “hyperactive” in a culture that typically discourages uniqueness (e.g., Japan) as compared to a Western culture (e.g., Israel); therefore the effect of inhibiting the L-IFG was expected to be higher in Japanese.To support this hypothesis we altered L-IFG activation using tDCS (transcranial direct current stimulation) in 30 Japanese and 30 Israeli participants and examined the effect of anodal and cathodal stimulation on divergent thinking (DT). Regardless of culture, cathodal stimulation increased creativity compared to sham, while anodal stimulation diminished creativity. Although cultural differences were found in DT scores, stimulation had no differential effect between the cultures. Taken together, the results confirm that the L-IFG plays a key role in creativity across cultures. The null findings regarding the expected interaction between stimulation and culture are discussed.