The underlying neural bases of the reversal error while solving algebraic word problems.

Problem solving is a core element in mathematical learning. The reversal error in problem solving occurs when students are able to recognize the information in the statement of comparison word problems, but they reverse the relationship between two variables when building the equations. Functional magnetic resonance images were acquired to identify for the first time the neural bases associated with the reversal error. The neuronal bases linked to this error have been used as inputs in 13 classifiers to discriminate between reversal error and non-reversal error groups. We found brain activation in bilateral fronto-parietal areas in the participants who committed reversal errors, and only left fronto-parietal activation in those who did not, suggesting that the reversal error group needed a greater cognitive demand. Instead, the non-reversal error group seems to show that they have developed solid algebraic knowledge. Additionally, the results showed brain activation in the right middle temporal gyrus when comparing the reversal error vs non-reversal error groups. This activation would be associated with the semantic processing which is required to understand the statement and build the equation. Finally, the classifier results show that the brain areas activated could be considered good biomarkers to help us identify competent solvers.

A neuroimaging data set on problem solving in the case of the reversal error: Putamen data.

Structural Magnetic Resonance Images (sMRI) for a sample of university students were recorded. Out of magnetic resonance, students performed a test of algebra problem solving. As we are interested in reversal errors, the test was prepared to detect this kind of error. Depending on the number of mistakes made, students were divided into two groups: one group contains 15 students that responded erroneously to more than 60% of the 16 questions, and the other group contains 18 students that did not make any mistake. We are interested in the more relevant brain structures for this neuroeducation problem. The analysis of these data can be found in Ferrando et al. (2020) [1]. The results of the volumetric analysis showed differences between groups in the right and left putamen. Therefore, both putamens were pre-processed and segmented to use them in the shape analysis. The dataset contains the slices of the left and right putamen and the left putamen of each of 33 subjects, 20 females. It also contains a vector that indicates the group to each subject belongs to.

Brain networks involved in accented speech processing.

We investigated the neural correlates of accented speech processing (ASP) with an fMRI study that overcame prior limitations in this line of research: we preserved intelligibility by using two regional accents that differ in prosody but only mildly in phonetics (Latin American and Castilian Spanish), and we used independent component analysis to identify brain networks as opposed to isolated regions. ASP engaged a speech perception network composed primarily of structures related with the processing of prosody (cerebellum, putamen, and thalamus). This network also included anterior fronto-temporal areas associated with lexical-semantic processing and a portion of the inferior frontal gyrus linked to executive control. ASP also recruited domain-general executive control networks related with cognitive demands (dorsal attentional and default mode networks) and the processing of salient events (salience network). Finally, the reward network showed a preference for the native accent, presumably revealing people's sense of social belonging.

Long-term brain effects of N-back training: an fMRI study.

Neurobehavioral effects of cognitive training have become a popular research issue. Specifically, behavioral studies have demonstrated the long-term efficacy of cognitive training of working memory functions, but the neural basis for this training have been studied only at short-term. Using fMRI, we investigate the cerebral changes produced by brief single n-back training immediately and 5 weeks after finishing the training. We used the data from a sample of 52 participants who were assigned to either an experimental condition (training group) or a no-contact control condition. Both groups completed three fMRI sessions with the same n-back task. Behavioral and brain effects were studied, comparing the conditions and sessions in both groups. Our results showed that n-back training improved performance in terms of accuracy and response speed in the trained group compared to the control group. These behavioral changes in trained participants were associated with decreased activation in various brain areas related to working memory, specifically the frontal superior/middle cortex, inferior parietal cortex, anterior cingulate cortex, and middle temporal cortex. Five weeks after training, the behavioral and brain changes remained stable. We conclude that cognitive training was associated with an improvement in behavioral performance and decreased brain activation, suggesting better neural efficiency that persists over time.

The dynamic imprint of word learning on the dorsal language pathway.

According to Hickok and Poeppel (2007), the acquisition of new vocabulary rests on the dorsal language pathway connecting auditory and motor areas. The present study tested this hypothesis longitudinally by measuring BOLD signal changes during a verbal repetition task and modulation of resting state functional connectivity (rs-FC) in the dorsal stream. Thirty-five healthy participants, divided into trained and control groups, completed fMRI sessions on days 1, 10, and 24. Between days 1 and 10, the trained group learned 84 new pseudowords associated with 84 native words. Task-related fMRI results showed a reduced activity in the IFG and STG while processing the learned vocabulary after training, returning to initial values two weeks later. Moreover, rs-fMRI analysis showed stronger rs-FC between the IFG and STG in the trained group than in the control group after learning, especially on day 24. These neural changes were more evident in participants with a larger vocabulary. Discussion focuses on the prominent role of the dorsal stream in vocabulary acquisition. Even when their meaning was known, newly learned words were again processed through the dorsal stream two weeks after learning, with the increase in rs-FC between auditory and motor areas being a relevant long-term imprint of vocabulary learning.

Functional connectivity in resting state as a phonemic fluency ability measure.

There is some evidence that functional connectivity (FC) measures obtained at rest may reflect individual differences in cognitive capabilities. We tested this possibility by using the FAS test as a measure of phonemic fluency. Seed regions of the main brain areas involved in this task were extracted from meta-analysis results (Wagner et al., 2014) and used for pairwise resting-state FC analysis. Ninety-three undergraduates completed the FAS test outside the scanner. A correlation analysis was conducted between the F-A-S scores (behavioral testing) and the pairwise FC pattern of verbal fluency regions of interest. Results showed that the higher FC between the thalamus and the cerebellum, and the lower FCs between the left inferior frontal gyrus and the right insula and between the supplementary motor area and the right insula were associated with better performance on the FAS test. Regression analyses revealed that the first two FCs contributed independently to this better phonemic fluency, reflecting a more general attentional factor (FC between thalamus and cerebellum) and a more specific fluency factor (FC between the left inferior frontal gyrus and the right insula). The results support the Spontaneous Trait Reactivation hypothesis, which explains how resting-state derived measures may reflect individual differences in cognitive abilities.

Modulation of Functional Connectivity in Auditory-Motor Networks in Musicians Compared with Nonmusicians.

Correlation of spontaneous fluctuations at rest between anatomically distinct brain areas are proposed to reflect the profile of individual a priori cognitive biases, coded as synaptic efficacies in cortical networks. Here, we investigate functional connectivity at rest (rs-FC) in musicians and nonmusicians to test for differences in auditory, motor, and audiomotor connectivity. As expected, musicians had stronger rs-FC between the right auditory cortex (AC) and the right ventral premotor cortex than nonmusicians, and this stronger rs-FC was greater in musicians with more years of practice. We also found reduced rs-FC between the motor areas that control both hands in musicians compared with nonmusicians, which was more evident in the musicians whose instrument required bimanual coordination and as a function of hours of practice. Finally, we replicated previous morphometric data to show an increased volume in the right AC in musicians, which was greater in those with earlier musical training, and that this anatomic feature was in turn related to greater rs-FC between auditory and motor systems. These results show that functional coupling within the motor system and between motor and auditory areas is modulated as a function of musical training, suggesting a link between anatomic and functional brain features.

Reduced posterior parietal cortex activation after training on a visual search task.

Gaining experience on a cognitive task improves behavioral performance and is thought to enhance brain efficiency. Despite the body of literature already published on the effects of training on brain activation, less research has been carried out on visual search attention processes under well controlled conditions. Thirty-six healthy adults divided into trained and control groups completed a pre-post letter-based visual search task fMRI study in one day. Twelve letters were used as targets and ten as distractors. The trained group completed a training session (840 trials) with half the targets between scans. The effects of training were studied at the behavioral and brain levels by controlling for repetition effects using both between-subjects (trained vs. control groups) and within-subject (trained vs. untrained targets) controls. The trained participants reduced their response speed by 31% as a result of training, maintaining their accuracy scores, whereas the control group hardly changed. Neural results revealed that brain changes associated with visual search training were circumscribed to reduced activation in the posterior parietal cortex (PPC) when controlling for group, and they included inferior occipital areas when controlling for targets. The observed behavioral and brain changes are discussed in relation to automatic behavior development. The observed training-related decreases could be associated with increased neural efficiency in specific key regions for task performance.

State and Training Effects of Mindfulness Meditation on Brain Networks Reflect Neuronal Mechanisms of Its Antidepressant Effect.

The topic of investigating how mindfulness meditation training can have antidepressant effects via plastic changes in both resting state and meditation state brain activity is important in the rapidly emerging field of neuroplasticity. In the present study, we used a longitudinal design investigating resting state fMRI both before and after 40 days of meditation training in 13 novices. After training, we compared differences in network connectivity between rest and meditation using common resting state functional connectivity methods. Interregional methods were paired with local measures such as Regional Homogeneity. As expected, significant differences in functional connectivity both between states (rest versus meditation) and between time points (before versus after training) were observed. During meditation, the internal consistency in the precuneus and the temporoparietal junction increased, while the internal consistency of frontal brain regions decreased. A follow-up analysis of regional connectivity of the dorsal anterior cingulate cortex further revealed reduced connectivity with anterior insula during meditation. After meditation training, reduced resting state functional connectivity between the pregenual anterior cingulate and dorsal medical prefrontal cortex was observed. Most importantly, significantly reduced depression/anxiety scores were observed after training. Hence, these findings suggest that mindfulness meditation might be of therapeutic use by inducing plasticity related network changes altering the neuronal basis of affective disorders such as depression.

Inferior frontal cortex activity is modulated by reward sensitivity and performance variability.

High reward sensitivity has been linked with motivational and cognitive disorders related with prefrontal and striatal brain function during inhibitory control. However, few studies have analyzed the interaction among reward sensitivity, task performance and neural activity. Participants (N=57) underwent fMRI while performing a Go/No-go task with Frequent-go (77.5%), Infrequent-go (11.25%) and No-go (11.25%) stimuli. Task-associated activity was found in inhibition-related brain regions, with different activity patterns for right and left inferior frontal gyri (IFG): right IFG responded more strongly to No-go stimuli, while left IFG responded similarly to all infrequent stimuli. Reward sensitivity correlated with omission errors in Go trials and reaction time (RT) variability, and with increased activity in right and left IFG for No-go and Infrequent-go stimuli compared with Frequent-go. Bilateral IFG activity was associated with RT variability, with reward sensitivity mediating this association. These results suggest that reward sensitivity modulates behavior and brain function during executive control.

Characterizing individual differences in reward sensitivity from the brain networks involved in response inhibition.

A "disinhibited" cognitive profile has been proposed for individuals with high reward sensitivity, characterized by increased engagement in goal-directed responses and reduced processing of negative or unexpected cues, which impairs adequate behavioral regulation after feedback in these individuals. This pattern is manifested through deficits in inhibitory control and/or increases in RT variability. In the present work, we aimed to test whether this profile is associated with the activity of functional networks during a stop-signal task using independent component analysis (ICA). Sixty-one participants underwent fMRI while performing a stop-signal task, during which a manual response had to be inhibited. ICA was used to mainly replicate the functional networks involved in the task (Zhang and Li, 2012): two motor networks involved in the go response, the left and right fronto-parietal networks for stopping, a midline error-processing network, and the default-mode network (DMN), which was further subdivided into its anterior and posterior parts. Reward sensitivity was mainly associated with greater activity of motor networks, reduced activity in the midline network during correct stop trials and, behaviorally, increased RT variability. All these variables explained 36% of variance of the SR scores. This pattern of associations suggests that reward sensitivity involves greater motor engagement in the dominant response, more distractibility and reduced processing of salient or unexpected events, which may lead to disinhibited behavior.

Bilingualism at the core of the brain. Structural differences between bilinguals and monolinguals revealed by subcortical shape analysis.

Naturally acquiring a language shapes the human brain through a long-lasting learning and practice process. This is supported by previous studies showing that managing more than one language from early childhood has an impact on brain structure and function. However, to what extent bilingual individuals present neuroanatomical peculiarities at the subcortical level with respect to monolinguals is yet not well understood, despite the key role of subcortical gray matter for a number of language functions, including monitoring of speech production and language control - two processes especially solicited by bilinguals. Here we addressed this issue by performing a subcortical surface-based analysis in a sample of monolinguals and simultaneous bilinguals (N=88) that only differed in their language experience from birth. This analysis allowed us to study with great anatomical precision the potential differences in morphology of key subcortical structures, namely, the caudate, accumbens, putamen, globus pallidus and thalamus. Vertexwise analyses revealed significantly expanded subcortical structures for bilinguals compared to monolinguals, localized in bilateral putamen and thalamus, as well as in the left globus pallidus and right caudate nucleus. A topographical interpretation of our results suggests that a more complex phonological system in bilinguals may lead to a greater development of a subcortical brain network involved in monitoring articulatory processes.

Functional Connectivity Between Superior Parietal Lobule and Primary Visual Cortex "at Rest" Predicts Visual Search Efficiency.

Spatiotemporal activity that emerges spontaneously "at rest" has been proposed to reflect individual a priori biases in cognitive processing. This research focused on testing neurocognitive models of visual attention by studying the functional connectivity (FC) of the superior parietal lobule (SPL), given its central role in establishing priority maps during visual search tasks. Twenty-three human participants completed a functional magnetic resonance imaging session that featured a resting-state scan, followed by a visual search task based on the alphanumeric category effect. As expected, the behavioral results showed longer reaction times and more errors for the within-category (i.e., searching a target letter among letters) than the between-category search (i.e., searching a target letter among numbers). The within-category condition was related to greater activation of the superior and inferior parietal lobules, occipital cortex, inferior frontal cortex, dorsal anterior cingulate cortex, and the superior colliculus than the between-category search. The resting-state FC analysis of the SPL revealed a broad network that included connections with the inferotemporal cortex, dorsolateral prefrontal cortex, and dorsal frontal areas like the supplementary motor area and frontal eye field. Noteworthy, the regression analysis revealed that the more efficient participants in the visual search showed stronger FC between the SPL and areas of primary visual cortex (V1) related to the search task. We shed some light on how the SPL establishes a priority map of the environment during visual attention tasks and how FC is a valuable tool for assessing individual differences while performing cognitive tasks.

Top-down attention regulates the neural expression of audiovisual integration.

The interplay between attention and multisensory integration has proven to be a difficult question to tackle. There are almost as many studies showing that multisensory integration occurs independently from the focus of attention as studies implying that attention has a profound effect on integration. Addressing the neural expression of multisensory integration for attended vs. unattended stimuli can help disentangle this apparent contradiction. In the present study, we examine if selective attention to sound pitch influences the expression of audiovisual integration in both behavior and neural activity. Participants were asked to attend to one of two auditory speech streams while watching a pair of talking lips that could be congruent or incongruent with the attended speech stream. We measured behavioral and neural responses (fMRI) to multisensory stimuli under attended and unattended conditions while physical stimulation was kept constant. Our results indicate that participants recognized words more accurately from an auditory stream that was both attended and audiovisually (AV) congruent, thus reflecting a benefit due to AV integration. On the other hand, no enhancement was found for AV congruency when it was unattended. Furthermore, the fMRI results indicated that activity in the superior temporal sulcus (an area known to be related to multisensory integration) was contingent on attention as well as on audiovisual congruency. This attentional modulation extended beyond heteromodal areas to affect processing in areas classically recognized as unisensory, such as the superior temporal gyrus or the extrastriate cortex, and to non-sensory areas such as the motor cortex. Interestingly, attention to audiovisual incongruence triggered responses in brain areas related to conflict processing (i.e., the anterior cingulate cortex and the anterior insula). Based on these results, we hypothesize that AV speech integration can take place automatically only when both modalities are sufficiently processed, and that if a mismatch is detected between the AV modalities, feedback from conflict areas minimizes the influence of this mismatch by reducing the processing of the least informative modality.

Reward sensitivity modulates brain activity in the prefrontal cortex, ACC and striatum during task switching.

Current perspectives on cognitive control acknowledge that individual differences in motivational dispositions may modulate cognitive processes in the absence of reward contingencies. This work aimed to study the relationship between individual differences in Behavioral Activation System (BAS) sensitivity and the neural underpinnings involved in processing a switching cue in a task-switching paradigm. BAS sensitivity was hypothesized to modulate brain activity in frontal regions, ACC and the striatum. Twenty-eight healthy participants underwent fMRI while performing a switching task, which elicited activity in fronto-striatal regions during the processing of the switch cue. BAS sensitivity was negatively associated with activity in the lateral prefrontal cortex, anterior cingulate cortex and the ventral striatum. Combined with previous results, our data indicate that BAS sensitivity modulates the neurocognitive processes involved in task switching in a complex manner depending on task demands. Therefore, individual differences in motivational dispositions may influence cognitive processing in the absence of reward contingencies.

Gray matter atrophy is associated with functional connectivity reorganization during the Paced Auditory Serial Addition Test (PASAT) execution in Multiple Sclerosis (MS).

BACKGROUND AND PURPOSE: We explored the relationship between gray matter atrophy and reorganization of functional connectivity in multiple sclerosis patients during execution of the Paced Auditory Serial Addition Test (PASAT). MATERIALS AND METHODS: Seventeen patients and 15 healthy controls were selected for the study. Atrophy was determined using voxel-based morphometry, and atrophy-related connectivity changes were assessed using psychophysiological interaction analysis. Group differences, and correlations with PASAT performance and radiological variables were also examined. RESULTS: Gray matter atrophy in MS patients was circumscribed to the bilateral posterior cingulate gyrus/precuneus. Compared with controls, patients showed stronger connectivity between the left posterior cingulate gyrus/precuneus, and the left middle temporal gyrus and left cerebellum. A regression analysis in controls showed a negative correlation between PASAT scores and functional connectivity between: (1) the left posterior cingulate gyrus/precuneus, and left pre/postcentral gyri and left occipital gyrus, and (2) the right posterior cingulate gyrus/precuneus, and bilateral cerebellum and left pre/postcentral gyri. Patients showed a negative correlation between brain parenchymal fraction and functional connectivity between the left posterior cingulate gyrus/precuneus and left cerebellum. CONCLUSION: Patients with early MS and little brain damage presented more connectivity during PASAT execution, which may be interpreted as compensatory processes that help preserve cognitive functions.

Do bilinguals show neural differences with monolinguals when processing their native language?

The present research used fMRI to measure brain activity in passive listening and picture-naming tasks with a group of early high proficient Spanish-Catalan bilinguals, in which Spanish was dominant, and a group of Spanish monolinguals. Both tasks were conducted in Spanish and the effect of cognateness was studied. The behavioural results showed slow naming responses in bilinguals. The fMRI results revealed that bilinguals and monolinguals differed only during the picture naming task. Unlike previous results, obtained mainly with L2, monolinguals displayed more activity in receptive language areas and less activity in the posterior cingulate cortex and right STG in the picture-naming task than bilinguals. As far as we know, this is the first study to investigate the neural basis of L1 processing in bilinguals and monolinguals by performing the task in the same language and in a monolingual context. The results indicate more efficient use of language networks in monolinguals because bilinguals utilised a more distributed network, which may imply subtle processing disadvantages.

Involvement of the human midbrain and thalamus in auditory deviance detection.

Prompt detection of unexpected changes in the sensory environment is critical for survival. In the auditory domain, the occurrence of a rare stimulus triggers a cascade of neurophysiological events spanning over multiple time-scales. Besides the role of the mismatch negativity (MMN), whose cortical generators are located in supratemporal areas, cumulative evidence suggests that violations of auditory regularities can be detected earlier and lower in the auditory hierarchy. Recent human scalp recordings have shown signatures of auditory mismatch responses at shorter latencies than those of the MMN. Moreover, animal single-unit recordings have demonstrated that rare stimulus changes cause a release from stimulus-specific adaptation in neurons of the primary auditory cortex, the medial geniculate body (MGB), and the inferior colliculus (IC). Although these data suggest that change detection is a pervasive property of the auditory system which may reside upstream cortical sites, direct evidence for the involvement of subcortical stages in the human auditory novelty system is lacking. Using event-related functional magnetic resonance imaging during a frequency oddball paradigm, we here report that auditory deviance detection occurs in the MGB and the IC of healthy human participants. By implementing a random condition controlling for neural refractoriness effects, we show that auditory change detection in these subcortical stations involves the encoding of statistical regularities from the acoustic input. These results provide the first direct evidence of the existence of multiple mismatch detectors nested at different levels along the human ascending auditory pathway.

Differential neural control in early bilinguals and monolinguals during response inhibition.

We tested the hypothesis that early bilinguals and monolinguals use different brain areas when performing nonlinguistic executive control tasks. For this, we explored brain activity of early bilinguals and monolinguals during a manual stop-signal paradigm. Behaviorally, bilinguals and monolinguals did not show significant differences in the task, which led us to compare brain activation that cannot be attributed to differences in performance. Analyses demonstrated that monolinguals activated the anterior cingulate cortex more than bilinguals when performing the stop-signal task. These results offer direct support for the notion that early bilingualism exerts an effect on neural circuitry responsible for executive control. Consistent with recent reports, we found that bilinguals used the anterior cingulate more efficiently than monolinguals to monitor nonlinguistic cognitive conflicts.

Abstinence duration modulates striatal functioning during monetary reward processing in cocaine patients.

Pre-clinical and clinical studies in cocaine addiction highlight alterations in the striatal dopaminergic reward system that subserve maintenance of cocaine use. Using an instrumental conditioning paradigm with monetary reinforcement, we studied striatal functional alterations in long-term abstinent cocaine-dependent patients and striatal functioning as a function of abstinence and treatment duration. Eighteen patients and 20 controls underwent functional magnetic resonance imaging during a Monetary Incentive Delay task. Region of interest analyses based on masks of the dorsal and ventral striatum were conducted to test between-group differences and the functional effects in the cocaine group of time (in months) with no more than two lapses from the first time patients visited the clinical service to seek treatment at the scanning time (duration of treatment), and the functional effects of the number of months with no lapses or relapses at the scanning session time (length of abstinence). We applied a voxel-wise and a cluster-wise FWE-corrected level (pFWE) at a threshold of P < 0.05. The patient group showed lower activation in the right caudate during reward anticipation than the control group. The regression analyses in the patients group revealed a positive correlation between duration of treatment and brain activity in the left caudate during reward anticipation. Likewise, length of abstinence negatively correlated with brain activity in the bilateral nucleus accumbens during monetary outcome processing. In conclusion, caudate and nucleus accumbens show a different brain response pattern to non-drug rewards during cocaine addiction, which can be modulated by treatment success.