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182 result(s) for "prefrontal cortex (PFC)"
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Altered neural connectivity in excitatory and inhibitory cortical circuits in autism
Converging evidence from diverse studies suggests that atypical brain connectivity in autism affects in distinct ways short- and long-range cortical pathways, disrupting neural communication and the balance of excitation and inhibition. This hypothesis is based mostly on functional non-invasive studies that show atypical synchronization and connectivity patterns between cortical areas in children and adults with autism. Indirect methods to study the course and integrity of major brain pathways at low resolution show changes in fractional anisotropy (FA) or diffusivity of the white matter in autism. Findings in post-mortem brains of adults with autism provide evidence of changes in the fine structure of axons below prefrontal cortices, which communicate over short- or long-range pathways with other cortices and subcortical structures. Here we focus on evidence of cellular and axon features that likely underlie the changes in short- and long-range communication in autism. We review recent findings of changes in the shape, thickness, and volume of brain areas, cytoarchitecture, neuronal morphology, cellular elements, and structural and neurochemical features of individual axons in the white matter, where pathology is evident even in gross images. We relate cellular and molecular features to imaging and genetic studies that highlight a variety of polymorphisms and epigenetic factors that primarily affect neurite growth and synapse formation and function in autism. We report preliminary findings of changes in autism in the ratio of distinct types of inhibitory neurons in prefrontal cortex, known to shape network dynamics and the balance of excitation and inhibition. Finally we present a model that synthesizes diverse findings by relating them to developmental events, with a goal to identify common processes that perturb development in autism and affect neural communication, reflected in altered patterns of attention, social interactions, and language.
Getting in synch: Unpacking the role of parent–child synchrony in the development of internalizing and externalizing behaviors
While substantial research supports the role of parent–child interactions on the emergence of psychiatric symptoms, few studies have explored biological mechanisms for this association. The current study explored behavioral and neural parent–child synchronization during frustration and play as predictors of internalizing and externalizing behaviors across a span of 1.5 years. Parent–child dyads first came to the laboratory when the child was 4–5 years old and completed the Disruptive Behavior Diagnostic Observation Schedule: Biological Synchrony (DB-DOS: BioSync) task while functional near-infrared spectroscopy (fNIRS) data were recorded. Parents reported on their child's internalizing and externalizing behaviors using the Child Behavior Checklist (CBCL) four times over 1.5 years. Latent growth curve (LGC) modeling was conducted to assess neural and behavioral synchrony as predictors of internalizing and externalizing trajectories. Consistent with previous investigations in this age range, on average, internalizing and externalizing behaviors decreased over the four time points. Parent–child neural synchrony during a period of play predicted rate of change in internalizing but not externalizing behaviors such that higher parent–child neural synchrony was associated with a more rapid decrease in internalizing behaviors. Our results suggest that a parent–child dyad's ability to coordinate neural activation during positive interactions might serve as a protective mechanism in the context of internalizing behaviors.
Does tDCS Enhance Complex Motor Skill Acquisition? Evidence from a Golf-Putting Task
Transcranial direct current stimulation (tDCS) modulates cortical excitability, thus inducing improvements in motor learning of simple tasks. In this study, we aimed to evaluate the effect of different tDCS conditions—anodal stimulation over the motor cortex (M1), anodal and cathodal stimulation over the prefrontal cortex (PFC), and sham—on the online and offline learning of a complex accuracy task (golf-putting) in novice golfers. Methods: A total of 40 young, healthy subjects (24 men, 16 women) without previous golf experience were randomly distributed in four groups receiving sham, anodal M1, anodal PFC or cathodal PFC tDCS. All subjects participated in two consecutive sessions. In the first session, they performed 15 blocks of 10 golf-putting along with tDCS stimulation. After 24 h, they performed the same task without tDCS. Results: Repeated measures ANOVA revealed a significant improvement in performance during the two consecutive golf-putting sessions regardless of the site and the stimulation conditions. Conclusion: Our findings suggest that tDCS over M1 or PFC does not confer additional benefits in the acquisition of complex, full-body motor skills such as golf-putting.
The role of dopamine and endocannabinoid systems in prefrontal cortex development: Adolescence as a critical period
The prefrontal cortex plays a central role in the control of complex cognitive processes including action control and decision making. It also shows a specific pattern of delayed maturation related to unique behavioral changes during adolescence and allows the development of adult cognitive processes. The adolescent brain is extremely plastic and critically vulnerable to external insults. Related to this vulnerability, adolescence is also associated with the emergence of numerous neuropsychiatric disorders involving alterations of prefrontal functions. Within prefrontal microcircuits, the dopamine and the endocannabinoid systems have widespread effects on adolescent-specific ontogenetic processes. In this review, we highlight recent advances in our understanding of the maturation of the dopamine system and the endocannabinoid system in the prefrontal cortex during adolescence. We discuss how they interact with GABA and glutamate neurons to modulate prefrontal circuits and how they can be altered by different environmental events leading to long-term neurobiological and behavioral changes at adulthood. Finally, we aim to identify several future research directions to help highlight gaps in our current knowledge on the maturation of these microcircuits.
Cortical Engagement Metrics During Reactive Balance Are Associated With Distinct Aspects of Balance Behavior in Older Adults
Heightened reliance on the cerebral cortex for postural stability with aging is well-known, yet the cortical mechanisms for balance control, particularly in relation to balance function, remain unclear. Here we aimed to investigate motor cortical activity in relation to the level of balance challenge presented during reactive balance recovery and identify circuit-specific interactions between motor cortex and prefrontal or somatosensory regions in relation to metrics of balance function that predict fall risk. Using electroencephalography, we assessed motor cortical beta power, and beta coherence during balance reactions to perturbations in older adults. We found that individuals with greater motor cortical beta power evoked following standing balance perturbations demonstrated lower general clinical balance function. Individual older adults demonstrated a wide range of cortical responses during balance reactions at the same perturbation magnitude, showing no group-level change in prefrontal- or somatosensory-motor coherence in response to perturbations. However, older adults with the highest prefrontal-motor coherence during the post-perturbation, but not pre-perturbation, period showed greater cognitive dual-task interference (DTI) and elicited stepping reactions at lower perturbation magnitudes. Our results support motor cortical beta activity as a potential biomarker for individual level of balance challenge and implicate prefrontal-motor cortical networks in distinct aspects of balance control involving response inhibition of reactive stepping in older adults. Cortical network activity during balance may provide a neural target for precision-medicine efforts aimed at fall prevention with aging.
Application of edaravone-loaded nanogel in alleviating behavioral deficits and oxidative stress in schizophrenia rat model
Schizophrenia is considered as a main one of the public health issues, and imposes numerous burdens on patients and society. We previously reported, the pathophysiology of schizophrenia is influenced by inflammation and mitochondrial dysfunction. Edaravone (EDV) as a potent antioxidant with neuroprotective traits, has been approved for the treatment of amyotrophic lateral sclerosis (ALS), effecting through neutralizing soluble/insoluble peroxyl radicals. However, the main disadvantages of EDV are its low stability in aqueous media, poor water solubility, and un-optimized bioavailability. To effectively address these obstacles, nanogel was utilized as the drug vehicle. The decoration of nanogel surface with glutathione (GSH) was carried out to elevate edaravone’s brain delivery. The probable improvement in drug delivery of edaravone loaded GSH-nanogel is the main hypothesis of this study. In order to mimic schizophrenia-like behaviors, we applied two month of post-weaning social isolation stress (PWSI) to rodent model. The choice of PWSI model was made due to the maturation and development of prefrontal cortex and hippocampus during adolescence. In addition to causing oxidative stress and upregulating genes linked to innate immunity in the prefrontal cortex (PFC), the data showed that PWSI triggered schizophrenia-like behaviors in rats. This study demonstrated that treatment with edaravone loaded GSH-nanogel decreased the impact of PWSI on behavioral dysfunctions and oxidative stress in the PFC of rats. Edaravone loaded GSH-nanogel (GSH-PMAA-EDV) down-regulated Toll-like receptor 4 ( Tlr-4 ) and AMP-activated protein kinase ( Ampk ) gene expression which are involved in inflammation and cellular energy homeostasis, respectively. Increase immunoreactivity feedback and Brain-derived neurotrophic factor ( Bdnf ) as direct impact in neurogenesis and neural cell plasticity was observed in EDV loaded GSH-nanogel treated groups. edaravone loaded GSH-nanogel (100 µg/kg) in comparison to free form of edaravone (5 mg/kg) revealed more beneficial effects, which might be useful for future clinical use especially for the treatment of schizophrenia.
Distinct phasic and sustained brain responses and connectivity of amygdala and bed nucleus of the stria terminalis during threat anticipation in panic disorder
Panic disorder (PD) patients are constantly concerned about future panic attacks and exhibit general hypersensitivity to unpredictable threat. We aimed to reveal phasic and sustained brain responses and functional connectivity of the amygdala and the bed nucleus of the stria terminalis (BNST) during threat anticipation in PD. Using functional magnetic resonance imaging (fMRI), we investigated 17 PD patients and 19 healthy controls (HC) during anticipation of temporally unpredictable aversive and neutral sounds. We used a phasic and sustained analysis model to disentangle temporally dissociable brain activations. PD patients compared with HC showed phasic amygdala and sustained BNST responses during anticipation of aversive v. neutral stimuli. Furthermore, increased phasic activation was observed in anterior cingulate cortex (ACC), insula and prefrontal cortex (PFC). Insula and PFC also showed sustained activation. Functional connectivity analyses revealed partly distinct phasic and sustained networks. We demonstrate a role for the BNST during unpredictable threat anticipation in PD and provide first evidence for dissociation between phasic amygdala and sustained BNST activation and their functional connectivity. In line with a hypersensitivity to uncertainty in PD, our results suggest time-dependent involvement of brain regions related to fear and anxiety.
Dopamine modulation of learning and memory in the prefrontal cortex: insights from studies in primates, rodents, and birds
In this review, we provide a brief overview over the current knowledge about the role of dopamine transmission in the prefrontal cortex during learning and memory. We discuss work in humans, monkeys, rats, and birds in order to provide a basis for comparison across species that might help identify crucial features and constraints of the dopaminergic system in executive function. Computational models of dopamine function are introduced to provide a framework for such a comparison. We also provide a brief evolutionary perspective showing that the dopaminergic system is highly preserved across mammals. Even birds, following a largely independent evolution of higher cognitive abilities, have evolved a comparable dopaminergic system. Finally, we discuss the unique advantages and challenges of using different animal models for advancing our understanding of dopamine function in the healthy and diseased brain.
Frontal Dysfunctions of Impulse Control – A Systematic Review in Borderline Personality Disorder and Attention-Deficit/Hyperactivity Disorder
Disorders such as borderline personality disorder (BPD) or attention-deficit/hyperactivity disorder (ADHD) are characterized by impulsive behaviors. Impulsivity as used in clinical terms is very broadly defined and entails different categories including personality traits as well as different cognitive functions such as emotion regulation or interference resolution and impulse control. Impulse control as an executive function, however, is neither cognitively nor neurobehaviorally a unitary function. Recent findings from behavioral and cognitive neuroscience studies suggest related but dissociable components of impulse control along functional domains like selective attention, response selection, motivational control, and behavioral inhibition. In addition, behavioral and neural dissociations are seen for proactive vs. reactive inhibitory motor control. The prefrontal cortex with its sub-regions is the central structure in executing these impulse control functions. Based on these concepts of impulse control, neurobehavioral findings of studies in BPD and ADHD were reviewed and systematically compared. Overall, patients with BPD exhibited prefrontal dysfunctions across impulse control components rather in orbitofrontal, dorsomedial, and dorsolateral prefrontal regions, whereas patients with ADHD displayed disturbed activity mainly in ventrolateral and medial prefrontal regions. Prefrontal dysfunctions, however, varied depending on the impulse control component and from disorder to disorder. This suggests a dissociation of impulse control related frontal dysfunctions in BPD and ADHD, although only few studies are hitherto available to assess frontal dysfunctions along different impulse control components in direct comparison of these disorders. Yet, these findings might serve as a hypothesis for the future systematic assessment of impulse control components to understand differences and commonalities of prefrontal cortex dysfunction in impulsive disorders.