Hippocampal long-term potentiation (LTP) induced by theta-burst pairing of Schaffer collateral inputs and postsynaptic firing is associated with localized increases in synaptic strength and dendritic ...excitability. Using the same protocol, we now demonstrate a decrease in cellular excitability that was blocked by the h-channel blocker ZD7288. This decrease was also induced by postsynaptic theta-burst firing alone, yet it was blocked by NMDA receptor antagonists, postsynaptic Ca2+ chelation, low concentrations of tetrodotoxin, omega-conotoxin MVIIC, calcium/calmodulin-dependent protein kinase II (CaMKII) inhibitors and a protein synthesis inhibitor. Increasing network activity with high extracellular K+ caused a similar reduction of cellular excitability and an increase in h-channel HCN1 protein. We propose that backpropagating action potentials open glutamate-bound NMDA receptors, resulting in an increase in I(h) and a decrease in overall excitability. The occurrence of such a reduction in cellular excitability in parallel with synaptic potentiation would be a negative feedback mechanism to normalize neuronal output firing and thus promote network stability.
In general, it is well recognized that both acute physical exercises and regular physical training influence brain plasticity and cognitive functions positively. However, growing evidence shows that ...the same physical exercises induce very heterogeneous outcomes across individuals. In an attempt to better understand this interindividual heterogeneity in response to acute and regular physical exercising, most research, so far, has focused on non-modifiable factors such as sex and different genotypes, while relatively little attention has been paid to exercise prescription as a modifiable factor. With an adapted exercise prescription, dosage can be made comparable across individuals, a procedure that is necessary to better understand the dose–response relationship in exercise–cognition research. This improved understanding of dose–response relationships could help to design more efficient physical training approaches against, for instance, cognitive decline.
All of us were born with a nervous system that isn’t just capable of change but was designed to change. Harnessing and directing the power of brain plasticity is the focus of most of modern stroke ...specific rehabilitation but the point is how do we make the most out of this kind of rehabilitation in individuals spheres of functioning and how does neuroplasticity it apply to stroke recovery? The current paper has two primary aims. First this study will investigate the effectiveness of some specific recovery options that promote neuroplasticity on the upper extremity sensorimotor recovery during the subacute phase after a stroke. The second aim of this paper is to explore the effectiveness of mixing and matching recovery options in post stroke rehabilitation training. Finding the appropriate evidence-based recovery options and the correct mix is part science, part intuition and part experience.
Amblyopia is a form of visual cortical impairment that arises from abnormal visual experience early in life. Most often, amblyopia is a unilateral visual impairment that can develop as a result of ...strabismus, anisometropia, or a combination of these conditions that result in discordant binocular experience. Characterized by reduced visual acuity and impaired binocular function, amblyopia places a substantial burden on the developing child. Although frontline treatment with glasses and patching can improve visual acuity, residual amblyopia remains for most children. Newer binocular-based therapies can elicit rapid recovery of visual acuity and may also improve stereoacuity in some children. Nevertheless, for both treatment modalities full recovery is elusive, recurrence of amblyopia is common, and improvements are negligible when treatment is administered at older ages. Insights derived from animal models about the factors that govern neural plasticity have been leveraged to develop innovative treatments for amblyopia. These novel therapies exhibit efficacy to promote recovery, and some are effective even at ages when conventional treatments fail to yield benefit. Approaches for enhancing visual system plasticity and promoting recovery from amblyopia include altering the balance between excitatory and inhibitory mechanisms, reversing the accumulation of proteins that inhibit plasticity, and harnessing the principles of metaplasticity. Although these therapies have exhibited promising results in animal models, their safety and ability to remediate amblyopia need to be evaluated in humans.
Presynaptic mitochondrial Ca.sup.2+ plays a critical role in the regulation of synaptic transmission and plasticity. The presynaptic bouton of the hippocampal mossy fiber (MF) is much larger in size ...than that of the Schaffer collateral (SC) synapse. Here we compare the structural and physiological characteristics of MF and SC presynaptic boutons to reveal functional and mechanistic differences between these two synapses. Our quantitative ultrastructural analysis using electron microscopy show many more mitochondria in MF presynaptic bouton cross-section profiles compared to SC boutons. Consistent with these results, post-tetanic potentiation (PTP), a form of presynaptic short-term plasticity dependent on mitochondrial Ca.sup.2+, is reduced by inhibition of mitochondrial Ca.sup.2+ release at MF synapses but not at SC synapses. However, blockade of mitochondrial Ca.sup.2+ release results in reduction of PTP at SC synapses by disynaptic MF stimulation. Furthermore, inhibition of mitochondrial Ca.sup.2+ release selectively decreases frequency facilitation evoked by short trains of presynaptic stimulation at MF synapses, while having no effect at SC synapses. Moreover, depletion of ER Ca.sup.2+ stores leads to reduction of PTP at MF synapses, but PTP is unaffected by ER Ca.sup.2+ depletion at SC synapses. These findings show that MF and SC synapses differ in presynaptic mitochondrial content as well as mitochondrial Ca.sup.2+ dependent synaptic plasticity, highlighting differential regulatory mechanisms of presynaptic plasticity at MF and SC synapses.
Introduction: Mentally Guided Imagery (MGI) has successfully been applied in sports for skill acquisition and performance enhancement. Despite the fact that athletes often use mental imagery as a ...part of their preparation, it has not been extensively explored as a learning technique in medical education. Few studies had highlighted mental imagery as a way to review and practice surgical skills efficiently. The present study aimed to assess the efficiency of intubation skills acquired through mental imagery in medical interns. Aim: To assess and compare the effect of Guided mental imagery and physical practice using mannequins on intubation technique among 40 medical Interns after seven days of training. Materials and Methods: The study was conducted in the Department of Emergency Medicine, Velammal Medical College and Hospital, Madurai over a period of seven days. Forty house surgeons were randomly divided into two groups. Group A (n=20) practiced MGI on intubation technique and Group B (n=20) practiced on mannequins one hour everyday for seven days. The performance of the students was assessed using a graded Objective Structured Clinical Examination (OSCE). Results: Results of Group A and Group B were analysed and compared statistically using paired and unpaired t-test. Though there was significant difference between the pre and post values in the MGI group (p<0.001), there was no statistically significant difference (p=0.216) in the post-intervention scores between the Mentally Guided Imagery (MGI) and physical practice group. Conclusion: Guided mental imagery was as effective as additional physical practice for medical students learning to perform intubation.
Depression represents a global mental health concern, and disproportionally affects women as they are twice more likely to be diagnosed than men. In this review, we provide a summary of evidence to ...support the notion that differences in depression between men and women span multiple facets of the disease, including epidemiology, symptomology, treatment, and pathophysiology. Through a lens of biological sex, we overview depression-related transcriptional patterns, changes in neuroanatomy and neuroplasticity, and immune signatures. We acknowledge the unique physiological and behavioral demands of pregnancy and motherhood by devoting special attention to depression occurring in the peripartum period. Specifically, we discuss issues surrounding the presentation, time course, treatment, and neurobiology of peripartum depression. We write this review with the intention of highlighting the encouraging advancements in our understanding of sex differences in depression, while underscoring the gaps that remain. A more systematic consideration of biological sex as a variable in depression research will be critical in the discovery and development of pharmacotherapies that are efficacious for both men and women.
•Physical activity is identified as a promising therapeutic method for depression•Explore what kind of exercise is more suitable for elderly patients with depression•Focus on the dose-response ...relationship between physical activity and depression•Physical activity compared with antidepressant medication•Potential mechanisms linking physical activity with depression
This study provides a comprehensive and updated review of the literature with respect to the relationship between physical activity and depression in older adults. The evidence from both observational studies and experimental studies are collected to present a discussion on the type and dose of physical activity, as well as the underlying mechanisms of physical activity and depression in older adults. Overall, the results from previous studies support a solid inverse relationship between physical activity and depression in older adults, while the dose-effect relationship between them, as well as different effects among different types of physical activities, remains largely unexplored. Depression in older adults is related to an array of negative health outcomes and is more chronic compared to that in younger adults. Physical activity has been regarded as a promising non-pharmaceutical method in treating and preventing depression in older adults. Further experimental work and research need to be done to develop theoretically grounded and evidence-based interventions to better advance our knowledge of this topic and effectively promote physical activity in older adults.
•Engaging in physical activity can reduce depressive symptoms.•Exercise stimulates several neuroplastic processes implicated in depression.•It also reduces inflammation and increases resilience to ...oxidative and physiological stress.•Exercise promotes self-esteem, social support and self-efficacy.•Understanding these mechanisms can improve the design of exercise interventions and maximise treatment response.
Physical activity can treat and prevent depressive symptoms, but its antidepressant mechanisms are yet to be established. In this review, we comprehensively assess key biological and psychosocial mechanisms through which physical activity exerts antidepressant effects, with a particular focus on exercise.
Exercise, a subset of physical activity, influences a range of biological and psychosocial processes also implicated in the pathophysiology of depression. We focus on the capacity for exercise to elicit changes in neuroplasticity, inflammation, oxidative stress, the endocrine system, self-esteem, social support and self-efficacy. We also discuss how a better understanding of these mechanisms can inform the way we design and implement exercise-based interventions to maximise their antidepressant effects on an individual basis. We conclude by presenting a conceptual framework of the key biological and psychosocial mechanisms underlying the relationship between physical activity and depressive symptoms, and the moderators and confounders that may influence it.
The synapse is the focus of experimental research and theory on the cellular mechanisms of nervous system plasticity and learning, but recent research is expanding the consideration of plasticity ...into new mechanisms beyond the synapse, notably including the possibility that conduction velocity could be modifiable through changes in myelin to optimize the timing of information transmission through neural circuits. This concept emerges from a confluence of brain imaging that reveals changes in white matter in the human brain during learning, together with cellular studies showing that the process of myelination can be influenced by action potential firing in axons. This Opinion article summarizes the new research on activity-dependent myelination, explores the possible implications of these studies and outlines the potential for new research.
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