Task-related Regions Research Articles

Joint Learning of Image Deblurring and Depth Estimation Through Adversarial Multi-Task Network

Self-supervised monocular depth estimation methods have achieved remarkable results on natural clear images. However, it is still a serious challenge to directly recover depth information from blurred images caused by long-time exposure while camera fast moving. To address this issue, we propose a unified framework for simultaneous deblurring and depth estimation (SDDE), which has higher coupling performance and flexibility compared with the simple concatenation strategy of deblurring model and depth estimation model. This framework mainly benefits from three features: (1) a novel Task-aware Fusion Module (TFM) to adaptively select the most relevant intermediate shared features for the dual decoder network by aggregating multi-scale features, (2) a unique Spatial Interaction Module (SIM) to learn higher-order representation in the encoder stage to better describe complex boundaries of different classes in high-dimensional space, and focuses on the task-related region by modeling the pairwise spatial correlation of the holistic tensor, (3) a Priors-Based Composite Regularization term to jointly optimize the shared encoder-dual decoder network. This work was evaluated on multiple datasets, including: Stereo blur [1], KITTI [2],NYUv2 [3], REDS [4] and our own large-scale stereo blur dataset, resulting in state-of-the-art results for depth estimation and image deblurring, respectively.

Variational relevance evaluation of individual fMRI data enables deconstruction of task-dependent neural dynamics

In neuroimaging research, univariate analysis has always been used to localize “representations” at the microscale, whereas network approaches have been applied to characterize transregional “operations”. How are representations and operations linked through dynamic interactions? We developed the variational relevance evaluation (VRE) method to analyze individual task fMRI data, which selects informative voxels during model training to localize the “representation”, and quantifies the dynamic contributions of single voxels across the whole-brain to different cognitive functions to characterize the “operation”. Using 15 individual fMRI data files for higher visual area localizers, we evaluated the characterization of selected voxel positions of VRE and revealed different object-selective regions functioning in similar dynamics. Using another 15 individual fMRI data files for memory retrieval after offline learning, we found similar task-related regions working in different neural dynamics for tasks with diverse familiarities. VRE demonstrates a promising horizon in individual fMRI research.

Structural correlates of language processing in primary progressive aphasia.

Understanding the relationships between brain structure and language behaviour in primary progressive aphasia provides crucial information about these diseases' pathomechanisms. However, previous investigations have been limited from providing a statistically reliable view of broad language abilities by sample size, variant focus and task focus. In this study, the authors aimed to determine the relationship between brain structure and language behaviour in primary progressive aphasia, to determine the degree to which task-associated regions were atrophied across disease variants and to determine the degree to which task-related atrophy overlaps across disease variants. Participants were 118 primary progressive aphasia patients and 61 healthy, age-matched controls tested from 2011 to 2018 in the German Consortium for Frontotemporal Lobar Degeneration cohort. Diagnosis of primary progressive aphasia required progressive deterioration of mainly speech and language for ≥ 2 years, and variant was diagnosed by the criteria of Gorno-Tempini et al. (Classification of primary progressive aphasia and its variants. Neurology. 2011;76(11):1006-1014). Twenty-one participants not fulfilling a specific subtype were classified as mixed-variant and excluded. Language tasks of interest included the Boston naming test, a German adaptation of the Repeat and Point task, phonemic and category fluency tasks and the reading/writing subtest of the Aachen Aphasia Test. Brain structure was measured by cortical thickness. We observed networks of language task-associated temporal, frontal and parietal cortex. Overlapping task-associated atrophy was observed in the left lateral, ventral and medial temporal lobes, middle and superior frontal gyri, supramarginal gyrus and insula. Some regions, primarily in the perisylvian region, were associated with language behaviour despite showing no significant atrophy. The results crucially extend less powerful studies associating brain and language measures in primary progressive aphasia. Cross-variant atrophy in task-associated regions suggests partially shared underlying deficits, whereas unique atrophy reinforces variant-specific deficits. Language task-related regions that are not obviously atrophied suggest regions of future network disruption and encourage understanding of task deficits beyond clearly atrophied cortex. These results may pave the way for new treatment approaches.

An altered reward system characterizes chronic migraine with medication overuse headache.

Medication overuse headache shares several characteristics with substance use disorders. However, key features of substance use disorders such as increased impulsivity and alterations in reward processing remain little explored in medication overuse headache. Temporal discounting and impulsive decision making behavior and the associated brain mechanisms were assessed in 26 chronic migraine patients with medication overuse headache and in 28 healthy controls. Regions-of-interest analyses were first performed for task-related regions, namely the ventral striatum and the ventromedial and dorsomedial prefrontal cortices. Resting-state functional connectivity between these regions were then explored. An additional 27 chronic migraine patients without medication overuse headache were included for comparison in the latter analysis. Patients with medication overuse headache showed steeper temporal discounting behavior than healthy controls. They also showed weaker subjective value representations in the dorsomedial prefrontal cortex, when accepting larger delayed rewards, and in ventral striatum and ventromedial prefrontal cortex, when accepting the smaller immediate reward. Resting-state functional connectivity was reduced among the valuation regions when comparing patients with medication overuse headache to the other two control groups. Patients with medication overuse headache were characterized by altered processing and dysconnectivity in the reward system during intertemporal choices and in the resting-state.

Quantitative description of the relationship between the enhancement of distraction-suppression and brain local state alteration after transcranial direct current stimulation.

Anodal transcranial direct current stimulation (tDCS) over the left dorsal lateral prefrontal cortex (lDLPFC) can improve distraction suppression ability, possibly by distantly regulating the connection properties of several large-scale brain networks and local brain state changes. However, little is known about the local state alteration that tDCS can induce in distant but task-related regions and the relationship between performance enhancement and local state alteration in potentially related regions, resulting in inefficient and uncertain tDCS regulation. We aimed to examine the alteration of brain local state before and after tDCS and its relationship with performance enhancement. With the within-subject design, the participants received anodal (1.5 mA) and sham tDCS at F3 (lDLPFC) for 20 min. The visual search task and resting-state functional magnetic resonance imaging (rsfMRI) were performed before and after stimulation. Anodal tDCS significantly enhanced distraction suppression. The amplitude of low-frequency fluctuation (ALFF) in the left parietal region significantly decreased, the decrement significantly positively correlated with performance enhancement after anodal tDCS. As well, the regional homogeneity (ReHo) in the left precuneus significantly increased, and the increasement significantly positively correlated with performance enhancement. Anodal tDCS over the lDLPFC can distantly modulate the local state of the brain and improve the distraction suppression ability. These two aspects are closely related and provide a direct and efficient approach to enhancing performance.

A causal role of anterior prefrontal-putamen circuit for response inhibition revealed by transcranial ultrasound stimulation in humans.

Stopping an inappropriate response requires the involvement of the prefrontal-subthalamic hyperdirect pathway. However, how the prefrontal-striatal indirect pathway contributes to stopping is poorly understood. In this study, transcranial ultrasound stimulation is used to perform interventions in a task-related region in the striatum. Functional magnetic resonance imaging (MRI) reveals activation in the right anterior part of the putamen during response inhibition, and ultrasound stimulation to the anterior putamen, as well as the subthalamic nucleus, results in significant impairments in stopping performance. Diffusion imaging further reveals prominent structural connections between the anterior putamen and the right anterior part of the inferior frontal cortex (IFC), and ultrasound stimulation to the anterior IFC also shows significant impaired stopping performance. These results demonstrate that the right anterior putamen and right anterior IFC causally contribute to stopping and suggest that the anterior IFC-anterior putamen circuit in the indirect pathway serves as an essential route for stopping.

Functional activation features of memory in successful agers across the adult lifespan

Much neuroimaging research has explored the neural mechanisms underlying successful cognitive aging. Two different patterns of functional activation, maintenance of youth-like activity and compensatory novel recruitment, have been proposed to represent different brain functional features underlying individual differences in cognitive aging. In this study, we investigated the functional features in individuals across the adult lifespan who appeared to resist age-related cognitive decline, in comparison to those with typical age-related declines, over the course of four years. We first implemented latent mixture modeling, a data-driven approach, to classify participants as successful and average agers in middle-aged, young-old, and very old groups, based on their baseline and longitudinal cognitive performance. Then, using fMRI with a subsequent memory paradigm at the follow-up visit, brain activation specifically related to successful encoding (i.e., subsequent memory effect: subsequently remembered with high confidence > subsequently forgotten) was compared between people who established successful cognitive aging versus average aging in the three age groups. Several differences in the subsequent memory effect were revealed. First, across core task-related regions commonly used during successful encoding, successful agers exhibited high subsequent memory effect, at a level comparable to the young control group, until very old age; in contrast, average agers showed reduced subsequent memory effect, compared to successful agers, beginning in young-old age when memory performance also reduced in average agers, compared to successful agers. Second, additional recruitment in prefrontal clusters, distant from the core task-related regions, were identified in the left superior frontal and right orbitofrontal cortices in successful agers of young-old age, possibly reflecting functional compensation in successful aging. In summary, successful agers demonstrate a pattern of youth-like activation spanning from middle age to young-old age, as well as novel frontal recruitment in young-old age. Overall, our study demonstrated evidence of two neural patterns related to successful cognitive aging, offering an integrated view of functional features underlying successful aging, and suggests the importance of studying individuals across the lifespan to understand brain changes occurring in mid and early-late life.

Reconfigured metabolism brain network in asymptomatic microtubule-associated protein tau mutation carriers: a graph theoretical analysis

BackgroundStudies exploring topological properties of the metabolic network during the presymptomatic stage of genetic frontotemporal dementia (FTD) are scarce. However, such knowledge is important for understanding brain function and disease pathogenesis. Therefore, we aimed to explore FTD-specific patterns of metabolism topology reconfiguration in microtubule-associated protein tau (MAPT) mutation carriers before the onset of symptoms.MethodsSix asymptomatic carriers of the MAPT P301L mutation were compared with 12 non-carriers who all belonged to the same family of FTD. For comparison, we included 32 behavioral variant FTD (bvFTD) patients and 33 unrelated healthy controls. Each participant underwent neuropsychological assessments, genetic testing, and a hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) scan. Voxel-wise gray matter volumes and standardized uptake value ratios were calculated and compared for structural MRI and fluorodeoxyglucose (FDG)-PET, separately. The sparse inverse covariance estimation method (SICE) was applied to topological properties and metabolic connectomes of brain functional networks derived from 18F-FDG PET/MRI data. Independent component analysis was used to explore the metabolic connectivity of the salience (SN) and default mode networks (DMN).ResultsThe asymptomatic MAPT carriers performed normal global parameters of the metabolism network, whereas bvFTD patients did not. However, we revealed lost hubs in the ventromedial prefrontal, orbitofrontal, and anterior cingulate cortices and reconfigured hubs in the anterior insula, precuneus, and posterior cingulate cortex in asymptomatic carriers compared with non-carriers, which overlapped with the comparisons between bvFTD patients and controls. Similarly, significant differences in local parameters of these nodes were present between asymptomatic carriers and non-carriers. The reduction in the connectivity of lost hub regions and the enhancement of connectivity between reconfigured hubs and components of the frontal cortex were marked during the asymptomatic stage. Metabolic connectivity within the SN and DMN was enhanced in asymptomatic carriers compared with non-mutation carriers but reduced in bvFTD patients relative to controls.ConclusionsOur findings showed that metabolism topology reconfiguration, characterized by the earliest involvement of medial prefrontal areas and active compensation in task-related regions, was present in the presymptomatic phase of genetic FTD with MAPT mutation, which may be used as an imaging biomarker of increased risk of FTD.

Towards More Efficient Security Inspection via Deep Learning: A Task-Driven X-ray Image Cropping Scheme.

X-ray imaging machines are widely used in border control checkpoints or public transportation, for luggage scanning and inspection. Recent advances in deep learning enabled automatic object detection of X-ray imaging results to largely reduce labor costs. Compared to tasks on natural images, object detection for X-ray inspection are typically more challenging, due to the varied sizes and aspect ratios of X-ray images, random locations of the small target objects within the redundant background region, etc. In practice, we show that directly applying off-the-shelf deep learning-based detection algorithms for X-ray imagery can be highly time-consuming and ineffective. To this end, we propose a Task-Driven Cropping scheme, dubbed TDC, for improving the deep image detection algorithms towards efficient and effective luggage inspection via X-ray images. Instead of processing the whole X-ray images for object detection, we propose a two-stage strategy, which first adaptively crops X-ray images and only preserves the task-related regions, i.e., the luggage regions for security inspection. A task-specific deep feature extractor is used to rapidly identify the importance of each X-ray image pixel. Only the regions that are useful and related to the detection tasks are kept and passed to the follow-up deep detector. The varied-scale X-ray images are thus reduced to the same size and aspect ratio, which enables a more efficient deep detection pipeline. Besides, to benchmark the effectiveness of X-ray image detection algorithms, we propose a novel dataset for X-ray image detection, dubbed SIXray-D, based on the popular SIXray dataset. In SIXray-D, we provide the complete and more accurate annotations of both object classes and bounding boxes, which enables model training for supervised X-ray detection methods. Our results show that our proposed TDC algorithm can effectively boost popular detection algorithms, by achieving better detection mAPs or reducing the run time.

Brain Structural-Functional Connectivity Relationship Underlying the Information Processing Speed.

Human cognition and behavior emerge from neuronal interactions on a brain structural architecture. The convergence (or divergence) between functional dynamics and structural connectivity (SC) and their relationship with cognition are still a pivotal question about the brain. We focused on the information processing speed (IPS), assessed by the Symbol Digit Modalities Test (SDMT), once delayed IPS underlies attention deficits in various clinical conditions. We hypothesize that the SC constrains but does not determine functional connectivity, and such a relationship is related to the cognitive performance. Blood oxygenation level-dependent and diffusion tensor images of healthy young volunteers were acquired in a 3T magnetic resonance imaging machine. Activation maps included the left and right middle frontal gyri, left superior parietal lobule, left precuneus, left inferior frontal gyrus (IFG), right cuneus, left lingual gyrus, and left declive. A network involving such regions and signal propagation from visual, through cognitive, up to motor regions was proposed. Random effects Bayesian model selection showed that the top-down connections have the highest expected and exceedance probabilities. Moreover, all pairs of task-related regions were connected by at least one tract, except for the left declive with the left IFG. The interactions between the right cuneus with left declive were related to the interindividual variability in SDMT performance. Altogether, our findings suggest that the IPS functional network is related to the highest SDMT scores when its effective endogenous connections are suppressed to the detriment of modulation caused by the experimental conditions, with the underlying structure providing low diffusion environments.

Local Use-Dependent Sleep in Wakefulness Links Performance Errors to Learning.

Sleep and wakefulness are no longer to be considered as discrete states. During wakefulness brain regions can enter a sleep-like state (off-periods) in response to a prolonged period of activity (local use-dependent sleep). Similarly, during nonREM sleep the slow-wave activity, the hallmark of sleep plasticity, increases locally in brain regions previously involved in a learning task. Recent studies have demonstrated that behavioral performance may be impaired by off-periods in wake in task-related regions. However, the relation between off-periods in wake, related performance errors and learning is still untested in humans. Here, by employing high density electroencephalographic (hd-EEG) recordings, we investigated local use-dependent sleep in wake, asking participants to repeat continuously two intensive spatial navigation tasks. Critically, one task relied on previous map learning (Wayfinding) while the other did not (Control). Behaviorally awake participants, who were not sleep deprived, showed progressive increments of delta activity only during the learning-based spatial navigation task. As shown by source localization, delta activity was mainly localized in the left parietal and bilateral frontal cortices, all regions known to be engaged in spatial navigation tasks. Moreover, during the Wayfinding task, these increments of delta power were specifically associated with errors, whose probability of occurrence was significantly higher compared to the Control task. Unlike the Wayfinding task, during the Control task neither delta activity nor the number of errors increased progressively. Furthermore, during the Wayfinding task, both the number and the amplitude of individual delta waves, as indexes of neuronal silence in wake (off-periods), were significantly higher during errors than hits. Finally, a path analysis linked the use of the spatial navigation circuits undergone to learning plasticity to off periods in wake. In conclusion, local sleep regulation in wakefulness, associated with performance failures, could be functionally linked to learning-related cortical plasticity.

Abstract WP151: Targeted Engagement of the Premotor Component of the Motor Network After Stroke

Introduction: Dorsal premotor cortex (PMd) is an important neural correlate of motor recovery after stroke. A protocol that targets engagement of this component of the motor network through changes in task demands may be a useful rehabilitation tool. Therefore, the purpose of this study was to determine the response to a period of practice targeted at PMd using a well-defined behavioral condition (action selection). Methods: Twelve individuals post-stroke (age: 56.9±7.7 years; months post-stroke: 46.5±46.7; UE FM motor score: 41.8±14.9) completed a task that required right or left movement of a joystick with the weaker hand under two conditions. In the Select Condition, the individual moved right or left based on an abstract, visual rule; this condition has been shown to activate PMd. In the Execute Condition, the individual moved the same direction on every trial. The task was practiced for four consecutive days and completed during functional MRI on Days 1 and 4. Results: Accuracy improved and reaction time (RT) cost (Select RT-Execute RT; represents the relative increase in planning time for the Select condition) decreased over practice ( p =0.005). On Day 1, Select Condition performance led to increased activation compared to Execute performance in bilateral PMd, bilateral parietal, and contralesional prefrontal cortices as expected. On Day 4, the increase in activation during the Select condition was overall less with a significant interaction in three contralesional brain regions: PMd, dorsolateral prefrontal, and anterior cingulate. Individuals with greater activation in the task relevant network (ipsilesional PMd and cingulate cortices, bilateral parietal cortices) on Day 1 had better performance (lower RT cost) on Day 4. Behavioral performance on Day 1 did not predict performance on Day 4 ( p =0.941). Conclusions: Behavioral practice targeted at the premotor component of the motor network can change the activation pattern in task-related regions. Additionally, the degree to which the task-related network is recruited initially may predict who responds best to behavioral practice targeted at that network. These finding may have implications for the structure of motor practice during rehabilitation after stroke.

Preliminary evidence of functional compensation in premanifest Huntington’s disease using a novel visuospatial working memory task

Evidence suggests that presymptomatic-HD individuals are able to recruit additional brain regions in non- task related regions and/or increase cortical activity in task-specific networks during task performance. This has been attributed to an early compensatory response. Despite the evidence, no study to date has explicitly characterised compensation in HD. In this study, we used a quantitative model of compensation, known as the CRUNCH (Compensation-Related Utilization of Neural Circuits Hypothesis), to characterise compensation in HD using functional magnetic resonance imaging (fMRI). The CRUNCH model postulates that cortical activity increases as task difficulty increases, to compensate for task difficulty. However, when individuals reach their maximum load capacity (usually at higher levels of difficulty), they exhibit less corti- cal activity and typically performance declines.

Structural Integrity in the Genu of Corpus Callosum Predicts Conflict-induced Functional Connectivity Between Medial Frontal Cortex and Right Posterior Parietal Cortex

Studies using the flanker task have reported that response conflict is detected by the medial frontal cortex (MFC). As a conflict alert system, the MFC shows enhanced functional communication with task-related regions. Previous studies have revealed individual differences in functional connectivity during cognitive task performance. However, the mechanisms underlying these individual differences remain unclear. In the current study, electroencephalography (EEG) was recorded while 30 subjects performed a flanker task that was modified to exclude feature integration and contingency learning. The diffusion tensor imaging (DTI) data were collected the day before the EEG session. FCz-P3/4 theta phase synchronization was used to measure functional connectivity between the MFC and posterior parietal cortex (PPC). Hierarchical regression analyses were used to assess the relationship between MFC-PPC conflict-induced theta phase synchronization and white matter integrity in significant regions derived from tract-based spatial statistics (TBSS) analysis. As expected, MFC-PPC theta phase synchronization was significantly enhanced during conflict, suggesting a conflict-induced functional connectivity. However, these findings were only found in the right hemisphere, which may be related to the asymmetrical role of the bilateral PPC in response conflict processing. Furthermore, hierarchical regression analyses revealed that 44% of individual variability in FCz-P4 conflict-induced theta phase synchronization could be explained by variations in axial diffusivity (AD) in the genu of the corpus callosum (gCC). These results demonstrated that structural integrity in the gCC predicts conflict-induced functional connectivity between the MFC and right PPC.

Stimulating thought: a functional MRI study of transcranial direct current stimulation in schizophrenia.

Individuals with schizophrenia typically suffer a range of cognitive deficits, including prominent deficits in working memory and executive function. These difficulties are strongly predictive of functional outcomes, but there is a paucity of effective therapeutic interventions targeting these deficits. Transcranial direct current stimulation is a novel neuromodulatory technique with emerging evidence of potential pro-cognitive effects; however, there is limited understanding of its mechanism. This was a double-blind randomized sham controlled pilot study of transcranial direct current stimulation on a working memory (n-back) and executive function (Stroop) task in 28 individuals with schizophrenia using functional magnetic resonance imaging. Study participants received 30 min of real or sham transcranial direct current stimulation applied to the left frontal cortex. The 'real' and 'sham' groups did not differ in online working memory task performance, but the transcranial direct current stimulation group demonstrated significant improvement in performance at 24 h post-transcranial direct current stimulation. Transcranial direct current stimulation was associated with increased activation in the medial frontal cortex beneath the anode; showing a positive correlation with consolidated working memory performance 24 h post-stimulation. There was reduced activation in the left cerebellum in the transcranial direct current stimulation group, with no change in the middle frontal gyrus or parietal cortices. Improved performance on the executive function task was associated with reduced activity in the anterior cingulate cortex. Transcranial direct current stimulation modulated functional activation in local task-related regions, and in more distal nodes in the network. Transcranial direct current stimulation offers a potential novel approach to altering frontal cortical activity and exerting pro-cognitive effects in schizophrenia.

P131 Phase-dependent modulations of brain activity and connectivity are dependent on cognitive state

Question Oscillations in the theta range (4–8 Hz) are a good candidate to coordinate neuronal ensembles during cognitive control. TACS has been shown to modulate cognitive function in a phase dependent manner. In this study we tested the effect of tACS in two paradigms with different levels of cognitive demand: a low-cognitive demand choice-reaction task (CRT); and a high-cognitive demand 2-back task. Simultaneous tACS/fMRI was used to test the hypothesis that the effects of tACS on brain activity and connectivity depend on cognitive state as well as the phase of stimulation. Methods TACS was delivered over F4 and P4 (with a common return in T8), at 6 Hz, 1 mA (Fig. 1 Download : Download high-res image (363KB) Download : Download full-size image ). Experiment 1: 10 subjects performed 3 sessions of each tACS condition “Synchronized” (0°), “Desynchronized” (180°), and sham stimulation. Experiment 2: 24 subjects had concurrent tACS and fMRI (3T, Siemens). Results Experiment 1: TACS delivered in the “synchronized” condition significantly improved reaction times in the high-cognitive demanding task as compared to the sham and “desynchronized” conditions. There was no effect of tACS in the tasks with low-cognitive demands. Experiment 2: 1. Distinct effects of tACS were seen for tasks with different levels of cognitive demand and the effect of tACS on brain activation is phase-dependent (Fig. 2 Download : Download high-res image (507KB) Download : Download full-size image ). In the 2-back task, tACS delivered in the “synchronized” condition elicited an increase in activity in task-related regions. In contrast, the “desynchronized” condition resulted in increased deactivation of the default-mode network. 2. tACS modulates brain connectivity in a task- and phase-dependent manner. PPI analysis showed that 0° stimulation modulated functional connectivity between the stimulated frontoparietal regions and regions involved in cognitive control. 3. Participants that had increased brain activity during the “synchronized” condition showed faster reaction times in the 2-back task (r = −0.4917, p = 0.02). Conclusions We demonstrate that tACS modulates brain activity and functional connectivity in a phase-dependent manner, which is dependent on cognitive task performance. TACS increases task-relevant functional connectivity within regions involved in cognitive control, providing a mechanistic insight how the technique enhances cognitive function.

Neural patterns underlying the effect of negative distractors on working memory in older adults

Working memory (WM) declines with age. Older adults, however, perform similar to younger adults in WM tasks with negative distractors at low WM load. To clarify the neural basis of this phenomenon, older (n = 28) and younger (n = 24) adults performed an emotional n-back task during an fMRI scan, and activity in task-related regions was examined. Comparing negative with neutral distraction at low WM load, older adults demonstrated shorter reaction times (RT) and reduced activation in frontoparietal regions: bilateral middle frontal gyrus (MFG) and left parietal cortex. They also had greater coherence within the frontoparietal network, as well as greater deactivation of the ventromedial prefrontal cortex and the amygdala. These patterns probably contributed to the older adults' diminished distractibility by negative task-irrelevant stimuli. Since recruitment of control mechanisms was less required, the frontoparietal network was less activated and performance was improved. Faster RT during the negative condition was related to lesser activation of the MFG in both age groups, corroborating the functional significance of this region to WM across the lifespan.

Training Working Memory in Childhood Enhances Coupling between Frontoparietal Control Network and Task-Related Regions.

Working memory is a capacity upon which many everyday tasks depend and which constrains a child's educational progress. We show that a child's working memory can be significantly enhanced by intensive computer-based training, relative to a placebo control intervention, in terms of both standardized assessments of working memory and performance on a working memory task performed in a magnetoencephalography scanner. Neurophysiologically, we identified significantly increased cross-frequency phase amplitude coupling in children who completed training. Following training, the coupling between the upper alpha rhythm (at 16 Hz), recorded in superior frontal and parietal cortex, became significantly coupled with high gamma activity (at ∼90 Hz) in inferior temporal cortex. This altered neural network activity associated with cognitive skill enhancement is consistent with a framework in which slower cortical rhythms enable the dynamic regulation of higher-frequency oscillatory activity related to task-related cognitive processes. Whether we can enhance cognitive abilities through intensive training is one of the most controversial topics of cognitive psychology in recent years. This is particularly controversial in childhood, where aspects of cognition, such as working memory, are closely related to school success and are implicated in numerous developmental disorders. We provide the first neurophysiological account of how working memory training may enhance ability in childhood, using a brain recording technique called magnetoencephalography. We borrowed an analysis approach previously used with intracranial recordings in adults, or more typically in other animal models, called "phase amplitude coupling."

Neural effects of methylphenidate and nicotine during smooth pursuit eye movements

IntroductionNicotine and methylphenidate are putative cognitive enhancers in healthy and patient populations. Although they stimulate different neurotransmitter systems, they have been shown to enhance performance on overlapping measures of attention. So far, there has been no direct comparison of the effects of these two stimulants on behavioural performance or brain function in healthy humans. Here, we directly compare the two compounds using a well-established oculomotor biomarker in order to explore common and distinct behavioural and neural effects. MethodsEighty-two healthy male non-smokers performed a smooth pursuit eye movement task while lying in an fMRI scanner. In a between-subjects, double-blind design, subjects either received placebo (placebo patch and capsule), nicotine (7mg nicotine patch and placebo capsule), or methylphenidate (placebo patch and 40mg methylphenidate capsule). ResultsThere were no significant drug effects on behavioural measures. At the neural level, methylphenidate elicited higher activation in left frontal eye field compared to nicotine, with an intermediate response under placebo. DiscussionThe reduced activation of task-related regions under nicotine could be associated with more efficient neural processing, while increased hemodynamic response under methylphenidate is interpretable as enhanced processing of task-relevant networks. Together, these findings suggest dissociable neural effects of these putative cognitive enhancers.

Neural activity during self-referential working memory and the underlying role of the amygdala in social anxiety disorder

Self-referential processing, theory of mind, and working memory are distorted in social anxiety disorder (SAD). This study aimed to investigate characteristics of altered self-referential working memory processing and resting-state functional connectivity in patients with SAD. Twenty patients and 20 healthy controls underwent functional magnetic resonance imaging at resting-state and while performing a working memory task containing faces with self-referential positive or negative comments and three memory phases (encoding, maintenance, and retrieval). Task-related results were compared between groups and tested for correlations. Resting-state connectivity between amygdala subregions and regions showing a task-related difference was also compared between groups. Patients compared to controls showed augmented memory for the negative comments, hyperactivation of the dorsomedial prefrontal cortex and temporo-parietal junction during encoding, and hypoactivation of the dorsolateral prefrontal cortex and insula during retrieval. At resting-state, increased connectivity of amygdala subregions with multiple task-related regions was found in patients. These findings suggest that the encoding process in SAD is accompanied by altered involvement of self-referential processing and theory of mind, whereas the retrieval process reflects impaired cognitive control. These memory-related processing may be affected by predisposing resting-state hyperconnectivity with the amygdala, and may underlie a hypersensitivity to negative comments and post-event reflection in SAD.