Running induces widespread structural alterations in the hippocampus and entorhinal cortex

Tau, amyloid, iron, oligodendrocytes ferroptosis, and inflammaging in the hippocampal formation of aged rats submitted to an aerobic exercise program

Alzheimer's disease is a progressive neurodegenerative disease affecting memory, language, and thinking with no curative treatment. Symptoms appear gradually, and pathological brain changes may occur twenty years before the physical and psychological signs, pointing to the urgent development of preventive interventions. Physical activity has been investigated as a preventive tool to defeat the main biological features of AD: pathological amyloid protein plaques, tau tangles, myelin degeneration, and iron deposits in the brain. This work quantifies tau tangles, amyloid, iron, and ferroptosis in oligodendrocytes in the aged rat hippocampal formation and statistically correlates neuron-neuron, neuron-glia, and glia-glia crosstalk and the effect of physical exercise on it. Our results indicate that iron overload in the oligodendrocytes is an inducer of ferroptosis; physical exercise reduces inflammaging, and improves axon-myelin volume relations; tau, amyloid, iron, and hippocampal formation cells present statistical correlations. Our data suggest the beneficial effects of physical exercise in AD and a mathematical relationship between the hippocampal formation cells in sedentary and active individuals, which should be considered in human and animal studies as a guide to a better understanding of crosstalk physiology.

Effects of high-intensity interval training and moderate-intensity continuous training on neural dynamics and firing in the CA1-MEC region of mice

The aim of this study is to investigate the differential impacts of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on neural circuit dynamics and neuronal firing in the hippocampal CA1 subregion (CA1) region and medial entorhinal cortex (MEC) of mice. Forty-two male ICR mice were randomized into control, HIIT, and MICT groups. Electrophysiological recordings were performed pre- and postintervention to assess neural circuit dynamics and neuronal firing patterns in the CA1-MEC pathway. Both exercise protocols increased local field potential (LFP) coherence, with MICT showing a more pronounced effect on δ and γ coherences (P < 0.05). Both modalities reduced δ power spectral density (PSD) (HIIT, P < 0.05; MICT, P < 0.01) and elevated θ, β, and γ PSDs. Neuronal firing frequency improved in both CA1 and MEC following HIIT and MICT (P < 0.05). HIIT enhanced firing regularity in CA1 (P < 0.05), whereas MICT improved regularity in both regions (P < 0.05). Both protocols reduced firing latency (HIIT, P < 0.05; MICT, P < 0.01) and enhanced burst firing ratio, interburst interval (IBI), burst duration (BD), and LFP phase locking (P < 0.05 or P < 0.01). Notably, MICT significantly improved spatial working memory and novel recognition abilities, as evidenced by increased novel arm time, entries, and preference index (P < 0.01). This study reveals that both HIIT and MICT positively impact neural processing and information integration in the CA1-MEC network of mice. Notably, MICT exhibits a more pronounced impact on neural functional connectivity and cognitive function compared with HIIT. These findings, coupled with the similarities in hippocampal electrophysiological characteristics between rodents and humans, suggest potential exercise-mediated neural plasticity and cognitive benefits in humans.NEW & NOTEWORTHY This study is the first to investigate HIIT and MICT's effects on neural activity in the mouse CA1-MEC circuit, demonstrating that exercise modulates processing, enhances integration, and boosts cognitive performance. Due to similar hippocampal electrophysiology in rodents and humans during movement and navigation, our findings suggest implications for human brain neural changes, advancing the understanding of neurophysiological mechanisms underlying exercise-cognition interactions and informing exercise recommendations for cognitive health.

Addressing the Effect of Exercise on Glial Cells: Focus on Ependymal Cells

A growing body of research highlights the positive impact of regular physical activity on improving physical and mental health. On the other hand, physical inactivity is one of the leading risk factors for noncommunicable diseases and death worldwide. Exercise profoundly impacts various body districts, including the central nervous system. Here, overwhelming evidence exists that physical exercise affects neurons and glial cells, by promoting their interaction. Physical exercise directly acts on ependymal cells by promoting their proliferation and activation, maintaing brain homeostasis in healthy animals and promote locomotor recovery after spinal cord injury. This review aims to describe the main anatomical characteristics and functions of ependymal cells and provide an overview of the effects of different types of physical exercise on glial cells, focusing on the ependymal cells.

Hippocampal long-term potentiation is modulated by exercise-induced alterations in dopaminergic synaptic transmission in mice selectively bred for high voluntary wheel running

BackgroundHigh-Runner (HR) mice, selectively bred for increased voluntary wheel running behavior, exhibit heightened motivation to run. Exercise has been shown to influence hippocampal long-term potentiation (LTP) and memory, and is neuroprotective in several neurodegenerative diseases.ObjectiveThis study aimed to determine the impact of intense running in HR mice with wheel access on hippocampal LTP, compared to HR mice without wheels and non-selected control (C) mice with/without wheels. Additionally, we investigated the involvement of D1/D5 receptors and the dopamine transporter (DAT) in LTP modulation and examined levels of these proteins in HR and C mice.MethodsAdult female HR and C mice were individually housed with/without running wheels for at least two weeks. Hippocampal LTP of extracellular field excitatory postsynaptic potentials (fEPSPs) was measured in area CA1, and SKF-38393 (D1/D5 receptor agonist) and GBR 12909 (DAT inhibitor) were used to probe the role of D1/D5 receptors and DAT in LTP differences. Western blot analyses assessed D1/D5 receptor and DAT expression in the hippocampus, prefrontal cortex, and cerebellum.ResultsHR mice with wheel access showed significantly increased hippocampal LTP compared to those without wheels and to C mice with/without wheels. Treatment with SKF-38393 or GBR 12909 prevented the heightened LTP in HR mice with wheels, aligning it with levels in C mice. Hippocampal D1/D5 receptor levels were lower, and DAT levels were higher in HR mice compared to C mice. No significant changes were observed in other brain regions.ConclusionsThe increased hippocampal LTP seen in HR mice with wheel access may be related to alterations in dopaminergic synaptic transmission that underlie the neurophysiological basis of hyperactivity, motor disorders, and/or motivation.

Entorhinal cortex-hippocampal circuit connectivity in health and disease

The entorhinal cortex (EC) and hippocampal (HC) connectivity is the main source of episodic memory formation and consolidation. The entorhinal-hippocampal (EC-HC) connection is classified as canonically glutamatergic and, more recently, has been characterized as a non-canonical GABAergic connection. Recent evidence shows that both EC and HC receive inputs from dopaminergic, cholinergic, and noradrenergic projections that modulate the mnemonic processes linked to the encoding and consolidation of memories. In the present review, we address the latest findings on the EC-HC connectivity and the role of neuromodulations during the mnemonic mechanisms of encoding and consolidation of memories and highlight the value of the cross-species approach to unravel the underlying cellular mechanisms known. Furthermore, we discuss how EC-HC connectivity early neurodegeneration may contribute to the dysfunction of episodic memories observed in aging and Alzheimer's disease (AD). Finally, we described how exercise may be a fundamental tool to prevent or decrease neurodegeneration.

A 10-Year Review on Advancements in Identifying and Treating Intellectual Disability Caused by Genetic Variations

Intellectual disability (ID) is a prevalent neurodevelopmental disorder characterized by neurodevelopmental defects such as the congenital impairment of intellectual function and restricted adaptive behavior. However, genetic studies have been significantly hindered by the extreme clinical and genetic heterogeneity of the subjects under investigation. With the development of gene sequencing technologies, more genetic variations have been discovered, assisting efforts in ID identification and treatment. In this review, the physiological basis of gene variations in ID is systematically explained, the diagnosis and therapy of ID is comprehensively described, and the potential of genetic therapies and exercise therapy in the rehabilitation of individuals with intellectual disabilities are highlighted, offering new perspectives for treatment approaches.

Environmental enrichment reduces restricted repetitive behavior by altering gray matter microstructure

Restricted, repetitive behaviors are common symptoms in neurodevelopmental disorders including autism spectrum disorder. Despite being associated with poor developmental outcomes, repetitive behaviors remain poorly understood and have limited treatment options. Environmental enrichment attenuates the development of repetitive behaviors, but the exact mechanisms remain obscure. Using the C58 mouse model of repetitive behavior, we performed diffusion tensor imaging to examine microstructural alterations associated with the development of repetitive behavior and its attenuation by environmental enrichment. The C57BL/6 mouse strain, which displays little or no repetitive behavior, was used as a control group. We observed widespread differences in diffusion metrics between C58 mice and C57BL/6 mice. In juvenile C58 mice, repetitive motor behavior displayed strong negative correlations with fractional anisotropy in multiple gray matter regions, whereas in young adult C58 mice, high repetitive motor behavior was most strongly associated with lower fractional anisotropy and higher radial diffusivity in the striatum. Environmental enrichment increased fractional anisotropy and axial diffusivity throughout gray matter regions in the brains of juvenile C58 mice and overlapped predominantly with cerebellar and sensory regions associated with repetitive behavior. Our results suggest environmental enrichment reduces repetitive behavior development by altering gray matter microstructure in the cerebellum, medial entorhinal cortex, and sensory processing regions in juvenile C58 mice. Under standard laboratory conditions, early pathology in these regions appears to contribute to later striatal and white matter dysfunction in adult C58 mice. Future studies should examine the role these regions play in the development of repetitive behavior and the relationship between sensory processing and cerebellar deficits and repetitive behavior.

Exercise Improves Cerebral Blood Flow and Functional Outcomes in an Experimental Mouse Model of Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) are a growing threat to public health without any known treatment. The bilateral common carotid artery stenosis (BCAS) mouse model is valid for VCID. Previously, we have reported that remote ischemic postconditioning (RIPostC) during chronic cerebral hypoperfusion (CCH) induced by BCAS increases cerebral blood flow (CBF), improves cognitive function, and reduces white matter damage. We hypothesized that physical exercise (EXR) would augment CBF during CCH and prevent cognitive impairment in the BCAS model. BCAS was performed in C57/B6 mice of both sexes to establish CCH. One week after the BCAS surgery, mice were randomized to treadmill exercise once daily or no EXR for four weeks. CBF was monitored with an LSCI pre-, post, and 4 weeks post-BCAS. Cognitive testing was performed for post-BCAS after exercise training, and brain tissue was harvested for histopathology and biochemical test. BCAS led to chronic hypoperfusion resulting in impaired cognitive function and other functional outcomes. Histological examination revealed that BCAS caused changes in neuronal morphology and cell death in the cortex and hippocampus. Immunoblotting showed that BCAS was associated with a significant downregulate of AMPK and pAMPK and NOS3 and pNOS3. BCAS also decreased red blood cell (RBC) deformability. EXR therapy increased and sustained improved CBF and cognitive function, muscular strength, reduced cell death, and loss of white matter. EXR is effective in the BCAS model, improving CBF and cognitive function, reducing white matter damage, improving RBC deformability, and increasing RBC NOS3 and AMPK. The mechanisms by which EXR improves CBF and attenuates tissue damage need further investigation.

Stressful Life Events and Reward Processing in Adults: Moderation by Depression and Anhedonia

Background

Exposure to acute stress is associated with reduced reward processing in laboratory studies in animals and humans. However, less clear is the association between reward processing and exposure to naturalistic stressful life events. The goal of the current study was to provide a novel investigation of the relation between past 6-month stressful life events and reward processing, and the extent to which this relation was moderated by depression diagnostic status and state symptoms of anhedonia.

Methods

The current study included a secondary analysis of data from 107 adults (37 current-depressed, 25 past-depressed, 45 never-depressed; 75% women) drawn from two previous community studies. Past 6-month stressful life events were assessed with a rigorous contextual interview with independent ratings. Response to monetary reward was assessed with a probabilistic reward task.

Results

Among current-depressed participants, and among both current- and past-depressed participants with high levels of anhedonia, greater exposure to independent life events outside of individuals' control was significantly associated with poorer reward learning. In direct contrast, among those with low levels of anhedonia, greater exposure to independent life events was significantly associated with a greater overall bias toward the more frequently rewarded stimulus.

Conclusions

Results suggest that depression and anhedonia are uniquely associated with vulnerability to blunted reward learning in the face of uncontrollable stressors. In contrast, in the absence of anhedonia symptoms, heightened reward processing during or following independent stressful life event exposure may represent an adaptive response.

DISC1 and reelin interact to alter cognition, inhibition, and neurogenesis in a novel mouse model of schizophrenia

The etiology of schizophrenia (SCZ) is multifactorial, and depending on a host of genetic and environmental factors. Two putative SCZ susceptibility genes, Disrupted-in-Schizophrenia-1 (DISC1) and reelin (RELN), interact at a molecular level, suggesting that combined disruption of both may lead to an intensified SCZ phenotype. To examine this gene-gene interaction, we produced a double mutant mouse line. Mice with heterozygous RELN haploinsufficiency were crossed with mice expressing dominant-negative c-terminal truncated human DISC1 to produce offspring with both mutations (HRM/DISC1 mice). We used an array of behavioral tests to generate a behavioral phenotype for these mice, then examined the prefrontal cortex and hippocampus using western blotting and immunohistochemistry to probe for SCZ-relevant molecular and cellular alterations. Compared to wild-type controls, HRM/DISC1 mice demonstrated impaired pre-pulse inhibition, altered cognition, and decreased activity. Diazepam failed to rescue anxiety-like behaviors, paradoxically increasing activity in HRM/DISC1 mice. At a cellular level, we found increased α1-subunit containing GABA receptors in the prefrontal cortex, and a reduction in fast-spiking parvalbumin positive neurons. Maturation of adult-born neurons in the hippocampus was also altered in HRM/DISC1 mice. While there was no difference in the total number proliferating cells, more of these cells were in immature stages of development. Homozygous DISC1 mutation combined with RELN haploinsufficiency produces a complex phenotype with neuropsychiatric characteristics relevant to SCZ and related disorders, expanding our understanding of how multiple genetic susceptibility factors might interact to influence the variable presentation of these disorders.

Physical Exercise as an Intervention for Depression: Evidence for Efficacy and Mu-Opioid Receptors as a Mechanism of Action

Physical exercise is often cited as an important part of an intervention for depression, and there is empirical evidence to support this. However, the mechanism of action through which any potential antidepressant effects are produced is not widely understood. Recent evidence points toward the involvement of endogenous opioids, and especially the mu-opioid system, as a partial mediator of these effects. In this chapter, we discuss the current level of empirical support for physical exercise as either an adjunctive or standalone intervention for depression. We then review the extant evidence for involvement of endogenous opioids in the proposed antidepressant effects of exercise, with a focus specifically on evidence for mu-opioid system involvement.

Neuroinflammation, memory, and depression: new approaches to hippocampal neurogenesis

As one of most common and severe mental disorders, major depressive disorder (MDD) significantly increases the risks of premature death and other medical conditions for patients. Neuroinflammation is the abnormal immune response in the brain, and its correlation with MDD is receiving increasing attention. Neuroinflammation has been reported to be involved in MDD through distinct neurobiological mechanisms, among which the dysregulation of neurogenesis in the dentate gyrus (DG) of the hippocampus (HPC) is receiving increasing attention. The DG of the hippocampus is one of two niches for neurogenesis in the adult mammalian brain, and neurotrophic factors are fundamental regulators of this neurogenesis process. The reported cell types involved in mediating neuroinflammation include microglia, astrocytes, oligodendrocytes, meningeal leukocytes, and peripheral immune cells which selectively penetrate the blood-brain barrier and infiltrate into inflammatory regions. This review summarizes the functions of the hippocampus affected by neuroinflammation during MDD progression and the corresponding influences on the memory of MDD patients and model animals.

Voluntary Running Improves Behavioral and Structural Abnormalities in a Mouse Model of CDKL5 Deficiency Disorder

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a rare neurodevelopmental disease caused by mutations in the X-linked CDKL5 gene. CDD is characterized by a broad spectrum of clinical manifestations, including early-onset refractory epileptic seizures, intellectual disability, hypotonia, visual disturbances, and autism-like features. The Cdkl5 knockout (KO) mouse recapitulates several features of CDD, including autistic-like behavior, impaired learning and memory, and motor stereotypies. These behavioral alterations are accompanied by diminished neuronal maturation and survival, reduced dendritic branching and spine maturation, and marked microglia activation. There is currently no cure or effective treatment to ameliorate the symptoms of the disease. Aerobic exercise is known to exert multiple beneficial effects in the brain, not only by increasing neurogenesis, but also by improving motor and cognitive tasks. To date, no studies have analyzed the effect of physical exercise on the phenotype of a CDD mouse model. In view of the positive effects of voluntary running on the brain of mouse models of various human neurodevelopmental disorders, we sought to determine whether voluntary daily running, sustained over a month, could improve brain development and behavioral defects in Cdkl5 KO mice. Our study showed that long-term voluntary running improved the hyperlocomotion and impulsivity behaviors and memory performance of Cdkl5 KO mice. This is correlated with increased hippocampal neurogenesis, neuronal survival, spine maturation, and inhibition of microglia activation. These behavioral and structural improvements were associated with increased BDNF levels. Given the positive effects of BDNF on brain development and function, the present findings support the positive benefits of exercise as an adjuvant therapy for CDD.

Protective effects of sleep duration and physical activity on cognitive performance are influenced by β-amyloid and brain volume but not tau burden among cognitively unimpaired older adults

BACKGROUND AND OBJECTIVES

Sleep and physical activity have gained traction as modifiable risk factors for Alzheimer's disease. Sleep duration is linked to amyloid-β clearance while physical activity is associated with brain volume maintenance. We investigate how sleep duration and physical activity are associated with cognition by testing if the associations between sleep duration or physical activity to cognition are explained by amyloid-β burden and brain volume, respectively. Additionally, we explore the mediating role of tau deposition in sleep duration-cognition and physical activity-cognition relationships.

METHODS

This cross-sectional study obtained data from participants in the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) study, a randomized clinical trial. In trial screening, cognitively unimpaired participants (age 65-85 years) underwent amyloid PET and brain MRI; APOE genotype and lifestyle questionnaire data were obtained. Cognitive performance was assessed using the Preclinical Alzheimer Cognitive Composite (PACC). Self-reported nightly sleep duration and weekly physical activity were the primary predictors. Regional Aβ and tau pathologies and volumes were the proposed variables influencing relationships between sleep duration or physical activity and cognition.

RESULTS

Aβ data were obtained from 4322 participants (1208 with MRI, 59% female, 29% amyloid positive). Sleep duration was associated with a Aβ composite score (β = -0.005, CI: (-0.01, -0.001)) and Aβ burden in the anterior cingulate (ACC) (β = -0.012, CI: (-0.017, -0.006)) and medial orbitofrontal cortices (MOC) (β = -0.009, CI: (-0.014, -0.005)). Composite (β = -1.54, 95% CI:(-1.93, -1.15)), ACC (β = -1.22, CI:(-1.54, -0.90)) and MOC (β = -1.44, CI:(-1.86, -1.02)) Aβ deposition was associated with PACC. Sleep duration-PACC association was explained by Aβ burden in path analyses. Physical activity was associated with hippocampal (β = 10.57, CI: (1.06, 20.08)), parahippocampal (β = 9.3, CI: (1.69, 16.91)), entorhinal (β = 14.68, CI: (1.75, 27.61), and fusiform gyral (β = 38.38, CI: (5.57, 71.18)) volumes, which were positively associated with PACC (p < 0.02 for hippocampus, entorhinal cortex and fusiform gyrus). Physical activity-cognition relationship was explained by regional volumes. PET tau imaging was available for 443 participants. No direct sleep duration-tau burden, physical activity by tau burden, or mediation by regional tau was observed in sleep duration-cognition or physical activity-cognition relationships.

DISCUSSION

Sleep duration and physical activity are associated with cognition through independent paths of brain Aβ and brain volume, respectively. These findings implicate neural and pathological mechanisms for the relationships between sleep duration and physical activity on cognition. Dementia risk reduction approaches that emphasize the adequate sleep duration and a physically active lifestyle may benefit those with risk for Alzheimer's disease.

MYELIN, AGING, AND PHYSICAL EXERCISE

Myelin sheath is a structure in neurons fabricated by oligodendrocytes and Schwann cells responsible for increasing the efficiency of neural synapsis, impulse transmission, and providing metabolic support to the axon. They present morpho-functional changes during health aging as deformities of the sheath and its fragmentation, causing an increased load on microglial phagocytosis, with Alzheimer's disease aggravating. Physical exercise has been studied as a possible protective agent for the nervous system, offering benefits to neuroplasticity. In this regard, studies in animal models for Alzheimer's and depression reported the efficiency of physical exercise in protecting against myelin degeneration. A reduction of myelin damage during aging has also been observed in healthy humans. Physical activity promotes oligodendrocyte proliferation and myelin preservation during old age, although some controversies remain. In this review, we will address how effective physical exercise can be as a protective agent of the myelin sheath against the effects of aging in physiological and pathological conditions.

Exercise increases information content and affects long-term stability of hippocampal place codes

Physical exercise is known to augment brain functioning, improving memory and cognition. However, while some of the physiological effects of physical activity on the brain are known, little is known about its effects on the neural code. Using calcium imaging in freely behaving mice, we study how voluntary exercise affects the quality and long-term stability of hippocampal place codes. We find that running accelerates the emergence of a more informative spatial code in novel environments and increases code stability over days and weeks. Paradoxically, although runners demonstrated an overall more stable place code than their sedentary peers, their place code changed faster when controlling for code quality level. A model-based simulation shows that the combination of improved code quality and faster representational drift in runners, but neither of these effects alone, could account for our results. Thus, exercise may enhance hippocampal function via a more informative and dynamic place code.

Running from Stress: Neurobiological Mechanisms of Exercise-Induced Stress Resilience

Chronic stress, even stress of a moderate intensity related to daily life, is widely acknowledged to be a predisposing or precipitating factor in neuropsychiatric diseases. There is a clear relationship between disturbances induced by stressful stimuli, especially long-lasting stimuli, and cognitive deficits in rodent models of affective disorders. Regular physical activity has a positive effect on the central nervous system (CNS) functions, contributes to an improvement in mood and of cognitive abilities (including memory and learning), and is correlated with an increase in the expression of the neurotrophic factors and markers of synaptic plasticity as well as a reduction in the inflammatory factors. Studies published so far show that the energy challenge caused by physical exercise can affect the CNS by improving cellular bioenergetics, stimulating the processes responsible for the removal of damaged organelles and molecules, and attenuating inflammation processes. Regular physical activity brings another important benefit: increased stress robustness. The evidence from animal studies is that a sedentary lifestyle is associated with stress vulnerability, whereas a physically active lifestyle is associated with stress resilience. Here, we have performed a comprehensive PubMed Search Strategy for accomplishing an exhaustive literature review. In this review, we discuss the findings from experimental studies on the molecular and neurobiological mechanisms underlying the impact of exercise on brain resilience. A thorough understanding of the mechanisms underlying the neuroprotective potential of preconditioning exercise and of the role of exercise in stress resilience, among other things, may open further options for prevention and therapy in the treatment of CNS diseases.

Relations between physical activity and hippocampal functional connectivity: Modulating role of mind wandering

Physical activity is critical for maintaining cognitive and brain health. Previous studies have indicated that the effect of physical activity on cognitive and brain function varies between individuals. The present study aimed to examine whether mind wandering modulated the relations between physical activity and resting-state hippocampal functional connectivity. A total of 99 healthy adults participated in neuroimaging data collection as well as reported their physical activity in the past week and their propensity to mind wandering during typical activities. The results indicated that mind wandering was negatively related to the resting-state functional connectivity between hippocampus and right inferior occipital gyrus. Additionally, for participants with higher level of mind wandering, physical activity was negatively related to hippocampal connectivity at left precuneus and right precentral gyrus. In contrast, such relations were positive at right medial frontal gyrus and bilateral precentral gyrus for participants with lower level of mind wandering. Altogether, these findings indicated that the relations between physical activity and hippocampal functional connectivity vary as a function of mind wandering level, suggesting that individual differences are important to consider when we aim to maintain or improve cognitive and brain health through increasing physical activity.

Exercise more efficiently regulates the maturation of newborn neurons and synaptic plasticity than fluoxetine in a CUS-induced depression mouse model

Depression, a common and important cause of morbidity and mortality worldwide, is commonly treated with antidepressants, electric shock and psychotherapy. Recently, increasing evidence has shown that exercise can effectively alleviate depression. To determine the difference in efficacy between exercise and the classic antidepressant fluoxetine in treating depression, we established four groups: the Control, chronic unpredictable stress (CUS/STD), running (CUS/RUN) and fluoxetine (CUS/FLX) groups. The sucrose preference test (SPT), the forced swimming test (FST), the tail suspension test (TST), immunohistochemistry, immunofluorescence and stereological analyses were used to clarify the difference in therapeutic efficacy and mechanism between exercise and fluoxetine in the treatment of depression. In the seventh week, the sucrose preference of the CUS/RUN group was significantly higher than that of the CUS/STD group, while the sucrose preference of the CUS/FLX group did not differ from that of the CUS/STD group until the eighth week. Exercise reduced the immobility time in the FST and TST, while fluoxetine only reduced immobility time in the TST. Hippocampal structure analysis showed that the CUS/STD group exhibited an increase in immature neurons and a decrease in mature neurons. Exercise reduced the number of immature neurons and increased the number of mature neurons, but no increase in the number of mature neurons was observed after fluoxetine treatment. In addition, both running and fluoxetine reversed the decrease in the number of MAP2+ dendrites in depressed mice. Exercise increased the number of spinophilin-positive (Sp+) dendritic spines in the hippocampal CA1, CA3, and dentate gyrus (DG) regions, whereas fluoxetine only increased the number of SP+ spines in the DG. In summary, exercise promoted newborn neuron maturation in the DG and regulated neuronal plasticity in three hippocampal subregions, which might explain why running exerts earlier and more comprehensive antidepressant effects than fluoxetine.

Exploring Daily Salivary Cortisol Patterns as Biomarkers of Chronic Chemotherapy-Induced Peripheral Neuropathy Pain

OBJECTIVES

Little is known about the biologic mechanisms of chronic chemotherapy-induced peripheral neuropathy (CIPN) pain. The purpose of this secondary analysis was to explore salivary cortisol patterns among cancer survivors with chronic CIPN pain to provide preliminary data regarding the role of hypothalamic-pituitary-adrenal axis dysregulation in the pathophysiology of this condition.

SAMPLE & SETTING

13 cancer survivors with chronic CIPN pain recruited from the breast, gastrointestinal, and gynecologic cancer centers at Dana-Farber Cancer Institute in Boston, Massachusetts.

METHODS & VARIABLES

Salivary cortisol was collected on awakening, 30 minutes after awakening, and before going to bed on two consecutive days. Cortisol awakening response and diurnal cortisol slope were calculated by averaging results across two days.

RESULTS

Cortisol was available from 13 participants. The median cortisol awakening response was -0.03 mcg/dl, and the average diurnal cortisol slope was -0.24 mcg/dl.

IMPLICATIONS FOR NURSING

Mechanism-based treatments are needed for cancer survivors with chronic CIPN pain. Nurse scientists may use study results to explore stress-related mechanisms of chronic CIPN pain.

Can exercise training teach us how to treat Alzheimer's disease?

Alzheimer's disease (AD) is the most common cause of dementia and there is currently no cure. Novel approaches to treat AD and curb the rapidly increasing worldwide prevalence and costs of dementia are needed. Physical inactivity is a significant modifiable risk factor for AD, estimated to contribute to 12.7% of AD cases worldwide. Exercise interventions in humans and animals have shown beneficial effects of exercise on brain plasticity and cognitive functions. In animal studies, exercise also improved AD pathology. The mechanisms underlying these effects of exercise seem to be associated mainly with exercise performance or cardiorespiratory fitness. In addition, exercise-induced molecules of peripheral origin seem to play an important role. Since exercise affects the whole body, there likely is no single therapeutic target that could mimic all the benefits of exercise. However, systemic strategies may be a viable means to convey broad therapeutic effects in AD patients. Here, we review the potential of physical activity and exercise training in AD prevention and treatment, shining light on recently discovered underlying mechanisms and concluding with a view on future development of exercise-free treatment strategies for AD.

Complicated Role of Exercise in Modulating Memory: A Discussion of the Mechanisms Involved

Evidence has shown the beneficial effects of exercise on learning and memory. However, many studies have reported controversial results, indicating that exercise can impair learning and memory. In this article, we aimed to review basic studies reporting inconsistent complicated effects of exercise on memory in rodents. Also, we discussed the mechanisms involved in the effects of exercise on memory processes. In addition, we tried to find scientific answers to justify the inconsistent results. In this article, the role of brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (involved in synaptic plasticity and neurogenesis), and vascular endothelial growth factor, nerve growth factor, insulin-like growth factor 1, inflammatory markers, apoptotic factors, and antioxidant system was discussed in the modulation of exercise effects on memory. The role of intensity and duration of exercise, and type of memory task was also investigated. We also mentioned to the interaction of exercise with the function of neurotransmitter systems, which complicates the prediction of exercise effect via altering the level of BDNF. Eventually, we suggested that changes in the function of neurotransmitter systems following different types of exercise (depending on exercise intensity or age of onset) should be investigated in further studies. It seems that exercise-induced changes in the function of neurotransmitter systems may have a stronger role than age, type of memory task, or exercise intensity in modulating memory. Importantly, high levels of interactions between neurotransmitter systems and BDNF play a critical role in the modulation of exercise effects on memory performance.

Interrelationships between exercise, functional connectivity, and cognition among healthy adults: A systematic review

The main purpose of this systematic review was to examine past literature focusing on the potential relationship between exercise (or physical activity or cardiorespiratory fitness [CRF]) and functional brain connectivity in healthy adults. Among the studies meeting this purpose, we also evaluated studies investigating whether, and how, functional connectivity may influence the exercise-cognition relationship. A systematic review was employed through several electronic databases (PsychInfo, PubMed, and Google Scholar) in accordance with PRISMA guidelines. The literature search identified 656 records, and a total of 12 studies met the inclusion criteria. Among these 12 studies, there were 4, 7, and 1 study, respectively, examining the relationship between exercise and frontal lobe connectivity, temporal lobe connectivity, and whole-brain connectivity. Also, 7 studies examined the relationship between functional connectivity and cognitive performance across multiple brain regions as a function of exercise. Existing literature suggests that CRF, habitual physical activity, and varying intensities of acute exercise can strengthen functional connections among a wide variety of regions and subcortical structures of the human brain. These exercise-induced functional connectivity changes within and between specific brain structures/networks supporting cognitive processing may improve various domains of cognitive function. Given these complex associations, a thorough understanding of how functional connectivity plays a mediating role in the exercise-cognition interaction is needed in future studies.

Therapeutic Benefits of Short-Arm Human Centrifugation in Multiple Sclerosis-A New Approach

Short-arm human centrifugation (SAHC) is proposed as a robust countermeasure to treat deconditioning and prevent progressive disability in a case of secondary progressive multiple sclerosis. Based on long-term physiological knowledge derived from space medicine and missions, artificial gravity training seems to be a promising physical rehabilitation approach toward the prevention of musculoskeletal decrement due to confinement and inactivity. So, the present study proposes a novel infrastructure based on SAHC to investigate the hypothesis that artificial gravity ameliorates the degree of disability. The patient was submitted to a 4-week training programme including three weekly sessions of 30 min of intermittent centrifugation at 1.5–2 g. During sessions, cardiovascular, muscle oxygen saturation (SmO₂) and electroencephalographic (EEG) responses were monitored, whereas neurological and physical performance tests were carried out before and after the intervention. Cardiovascular parameters improved in a way reminiscent of adaptations to aerobic exercise. SmO₂ decreased during sessions concomitant with increased g load, and, as training progressed, SmO₂ of the suffering limb dropped, both effects suggesting increased oxygen use, similar to that seen during hard exercise. EEG showed increased slow and decreased fast brain waves, with brain reorganization/plasticity evidenced through functional connectivity alterations. Multiple-sclerosis-related disability and balance capacity also improved. Overall, this study provides novel evidence supporting SAHC as a promising therapeutic strategy in multiple sclerosis, based on mechanical loading, thereby setting the basis for future randomized controlled trials.

Learning, Neurogenesis and Effects of Flavonoids on Learning

Learning and memory are two of our mind's most magical abilities. Different brain regions have roles to process and store different types of memories. The hippocampus is the part of the brain responsible for receiving information and storing it in the neocortex. One of the most impressive characteristics of the hippocampus is its capacity for neurogenesis which is a process, new neurons are produced and then transformed into mature neurons and integrated into neural circuits. The neurogenesis process in the hippocampus, an example of neuroplasticity in the adult brain, is believed to aid hippocampal-dependent learning and memory. New neurons are constantly produced in the hippocampus and integrated into the pre-existing neuronal network, this allows old memories already stored in the neocortex to be removed from the hippocampus and replaced with new ones. Factors affecting neurogenesis in the hippocampus may also affect hippocampal-dependent learning and memory. The flavonoids can exert particularly powerful actions in mammalian cognition and improve hippocampaldependent learning and memory by positively affecting hippocampal neurogenesis.

Effects of Rhythmic Interventions on Cognitive Abilities in Parkinson's Disease

OBJECTIVE

The objective of this study is to compare 2 different rhythmic, high-intensive interventions, that is, rhythmic speech-language therapy (rSLT) versus rhythmic balance-mobility training (rBMT), against a no-therapy (NT) condition in patients with Parkinson's disease and against healthy controls (HCs) with regard to the change in or enhancement of cognitive abilities.

METHODS

The 4 groups (rSLT: N = 16; rBMT: N = 10; NT: N = 18; and HC: N = 17) were matched for age, sex, and educational level and were tested in 6 cognitive domains: working memory, executive function, visuo-construction, episodic memory, attention, and word retrieval. Assessments took place at baseline, at 4 weeks (T1), and at 6 months (T2). Rhythmic interventions were provided 3 times per week for 4 weeks in total. To analyze true intervention effects between groups and across time, statistical analyses included reliable change index. Intergroup differences were assessed with multivariate assessment of variance, while differences within groups were assessed with 95% confidence intervals of mean difference.

RESULTS

The rSLT improved working memory and word retrieval (p < 0.05), possibly a beneficial transfer effect of the training method per se. In contrast, the NT group worsened in phonemic and semantic shifting (p < 0.01). Observed improvements in flexibility and in episodic memory in the HC may be linked to training effects of retesting.

CONCLUSIONS

Rhythmic cues are resistant to neurodegeneration and have a strong motivating factor. As thus, these may facilitate high-intensive and demanding training. Although both trainings were superior to NT, the improvement of cognitive abilities depends on the specific training method. Further, therapy may be more effective when delivered by a therapist rather than by an impersonal computer program.

Chemotherapy-Induced Cognitive Impairment and Hippocampal Neurogenesis: A Review of Physiological Mechanisms and Interventions

A wide range of cognitive deficits, including memory loss associated with hippocampal dysfunction, have been widely reported in cancer survivors who received chemotherapy. Changes in both white matter and gray matter volume have been observed following chemotherapy treatment, with reduced volume in the medial temporal lobe thought to be due in part to reductions in hippocampal neurogenesis. Pre-clinical rodent models confirm that common chemotherapeutic agents used to treat various forms of non-CNS cancers reduce rates of hippocampal neurogenesis and impair performance on hippocampally-mediated learning and memory tasks. We review the pre-clinical rodent literature to identify how various chemotherapeutic drugs affect hippocampal neurogenesis and induce cognitive impairment. We also review factors such as physical exercise and environmental stimulation that may protect against chemotherapy-induced neurogenic suppression and hippocampal neurotoxicity. Finally, we review pharmacological interventions that target the hippocampus and are designed to prevent or reduce the cognitive and neurotoxic side effects of chemotherapy.

Activity-based anorexia animal model: a review of the main neurobiological findings

BACKGROUND

The genesis of anorexia nervosa (AN), a severe eating disorder with a pervasive effect on many brain functions such as attention, emotions, reward processing, cognition and motor control, has not yet been understood. Since our current knowledge of the genetic aspects of AN is limited, we are left with a large and diversified number of biological, psychological and environmental risk factors, called into question as potential triggers of this chronic condition with a high relapse rate. One of the most valid and used animal models for AN is the activity-based anorexia (ABA), which recapitulates important features of the human condition. This model is generated from naïve rodents by a self-motivated caloric restriction, where a fixed schedule food delivery induces spontaneous increased physical activity.

AIM

In this review, we sought to provide a summary of the experimental research conducted using the ABA model in the pursuit of potential neurobiological mechanism(s) underlying AN.

METHOD

The experimental work presented here includes evidence for neuroanatomical and neurophysiological changes in several brain regions as well as for the dysregulation of specific neurochemical synaptic and neurohormonal pathways.

RESULTS

The most likely hypothesis for the mechanism behind the development of the ABA phenotype relates to an imbalance of the neural circuitry that mediates reward processing. Evidence collected here suggests that ABA animals show a large set of alterations, involving regions whose functions extend way beyond the control of reward mechanisms and eating habits. Hence, we cannot exclude a primary role of these alterations from a mechanistic theory of ABA induction.

CONCLUSIONS

These findings are not sufficient to solve such a major enigma in neuroscience, still they could be used to design ad hoc further experimental investigation. The prospect is that, since treatment of AN is still challenging, the ABA model could be more effectively used to shed light on the complex AN neurobiological framework, thus supporting the future development of therapeutic strategies but also the identification of biomarkers and diagnostic tools. Anorexia Nervosa (AN) is a severe eating disorder with a dramatic effect on many functions of our brain, such as attention, emotions, cognition and motion control. Since our current knowledge of the genetic aspects behind the development of AN is still limited, many biological, psychological and environmental factors must be taken into account as potential triggers of this condition. One of the most valid animal models for studying AN is the activity-based anorexia (ABA). In this model, rodents spontaneously limit food intake and start performing increased physical activity on a running wheel, a result of the imposition of a fixed time schedule for food delivery. In this review, we provide a detailed summary of the experimental research conducted using the ABA model, which includes extended evidence for changes in the anatomy and function of the brain of ABA rodents. The hope is that such integrated view will support the design of future experiments that will shed light on the complex brain mechanisms behind AN. Such advanced knowledge is crucial to find new, effective strategies for both the early diagnosis of AN and for its treatment.

Transcriptome Analysis in a Mouse Model of Premature Aging of Dentate Gyrus: Rescue of Alpha-Synuclein Deficit by Virus-Driven Expression or by Running Restores the Defective Neurogenesis

The dentate gyrus of the hippocampus and the subventricular zone are neurogenic niches where neural stem and progenitor cells replicate throughout life to generate new neurons. The Btg1 gene maintains the stem cells of the neurogenic niches in quiescence. The deletion of Btg1 leads to an early transient increase of stem/progenitor cells division, followed, however, by a decrease during adulthood of their proliferative capability, accompanied by apoptosis. Since a physiological decrease of neurogenesis occurs during aging, the Btg1 knockout mouse may represent a model of neural aging. We have previously observed that the defective neurogenesis of the Btg1 knockout model is rescued by the powerful neurogenic stimulus of physical exercise (running). To identify genes responsible for stem and progenitor cells maintenance, we sought here to find genes underlying this premature neural aging, and whose deregulated expression could be rescued by running. Through RNA sequencing we analyzed the transcriptomic profiles of the dentate gyrus isolated from Btg1 wild-type or Btg1 knockout adult (2-month-old) mice submitted to physical exercise or sedentary. In Btg1 knockout mice, 545 genes were deregulated, relative to wild-type, while 2081 genes were deregulated by running. We identified 42 genes whose expression was not only down-regulated in the dentate gyrus of Btg1 knockout, but was also counter-regulated to control levels by running in Btg1 knockout mice, vs. sedentary. Among these 42 counter-regulated genes, alpha-synuclein (Snca), Fos, Arc and Npas4 showed significantly greater differential regulation. These genes control neural proliferation, apoptosis, plasticity and memory and are involved in aging. In particular, Snca expression decreases during aging. We tested, therefore, whether an Snca-expressing lentivirus, by rescuing the defective Snca levels in the dentate gyrus of Btg1 knockout mice, could also reverse the aging phenotype, in particular the defective neurogenesis. We found that the exogenous expression of Snca reversed the Btg1 knockout-dependent decrease of stem cell proliferation as well as the increase of progenitor cell apoptosis. This indicates that Snca has a functional role in the process of neural aging observed in this model, and also suggests that Snca acts as a positive regulator of stem cell maintenance.

Short-term running exercise alters DNA methylation patterns in neuronal nitric oxide synthase and brain-derived neurotrophic factor genes in the mouse hippocampus and reduces anxiety-like behaviors

Running exercise has beneficial effects on brain health. However, the effects of relatively short-term running exercise (STEx) on behavior, and its underlying signaling pathways, are poorly understood. In this study, we evaluated the possibility that the regulation by STEx of brain-derived neurotrophic factor (BDNF) and neuronal nitric oxide synthase (nNOS, encoded by NOS1), which are important molecules for anxiety regulation, might involve mechanisms of epigenetic modification, such as DNA methylation. C57BL/6J male mice were divided into sedentary (SED, n = 12) and STEx (EX, n = 15) groups; STEx was conducted with the mice for a duration of 11 days. STEx reduced anxiety-like behaviors, and STEx reduced Nos1α and increased Bdnf exon I and IV mRNA levels in the hippocampus. Interestingly, behavioral parameters were associated with Bdnf exon I and IV and Nos1α mRNA levels in the ventral, but not dorsal, hippocampal region. However, STEx had no effect on peroxisome proliferator-activated receptor-γ coactivator 1α (Pgc-1α) or fibronectin type III domain-containing 5 (Fndc5) mRNA levels, which are relatively long-term exercise-induced upstream regulators of BDNF. In parallel with gene expression changes, we found, for the first time, that STEx downregulated Bdnf promoter IV and upregulated Nos1 DNA methylation levels in the hippocampus, and these patterns were partially different between the dorsal and ventral regions. These findings suggest that the beneficial effects of running exercise on mood regulation may be controlled by alterations in epigenetic mechanisms, especially in the ventral hippocampus. These effects occur even after a relatively short-term period of exercise.

Lifestyle-dependent microglial plasticity: training the brain guardians

Lifestyle is one of the most powerful instruments shaping mankind; the lifestyle includes many aspects of interactions with the environment, from nourishment and education to physical activity and quality of sleep. All these factors taken in complex affect neuroplasticity and define brain performance and cognitive longevity. In particular, physical exercise, exposure to enriched environment and dieting act through complex modifications of microglial cells, which change their phenotype and modulate their functional activity thus translating lifestyle events into remodelling of brain homoeostasis and reshaping neural networks ultimately enhancing neuroprotection and cognitive longevity.

Chronic AdipoRon Treatment Mimics the Effects of Physical Exercise on Restoring Hippocampal Neuroplasticity in Diabetic Mice

Administration of exercise mimetic drugs could be a novel therapeutic approach to combat comorbid neurodegeneration and metabolic syndromes. Adiponectin is an adipocyte-secreted hormone. In addition to its antidiabetic effect, adiponectin mediates the antidepressant effect of physical exercise associated with adult hippocampal neurogenesis. The antidiabetic effect of the adiponectin receptor agonist AdipoRon has been demonstrated, but its potential pro-cognitive and neurotrophic effects in the hippocampus under diabetic condition are still unclear. This study reported that chronic AdipoRon treatment for 2 weeks improved hippocampal-dependent spatial recognition memory in streptozotocin-induced diabetic mice. Besides, AdipoRon treatment increased progenitor cell proliferation and neuronal differentiation in the hippocampal dentate gyrus (DG) of diabetic mice. Furthermore, AdipoRon treatment significantly increased dendritic complexity, spine density, and N-methyl-D-aspartate receptor-dependent long-term potentiation (LTP) in the dentate region, and increased BDNF levels in the DG of diabetic mice. AdipoRon treatment activated AMPK/PGC-1α signalling in the DG, whereas increases in cell proliferation and LTP were not observed when PGC-1α signalling was pharmacologically inhibited. In sum, chronic AdipoRon treatment partially mimics the benefits of physical exercise for learning and memory and hippocampal neuroplasticity in the diabetic brain. The results suggested that AdipoRon could be a potential physical exercise mimetic to improve hippocampal plasticity and hence rescue learning and memory impairment typically associated with diabetes.

Neuroprotective Effects of Physical Activity via the Adaptation of Astrocytes

The multifold benefits of regular physical exercise have been largely demonstrated in human and animal models. Several studies have reported the beneficial effects of physical activity, both in peripheral tissues and in the central nervous system (CNS). Regular exercise improves cognition, brain plasticity, neurogenesis and reduces the symptoms of neurodegenerative diseases, making timeless the principle of “mens sana in corpore sano” (i.e., a healthy mind in a healthy body). Physical exercise promotes morphological and functional changes in the brain, acting not only in neurons but also in astrocytes, which represent the most numerous glial cells in the brain. The multiple effects of exercise on astrocytes comprise the increased number of new astrocytes, the maintenance of basal levels of catecholamine, the increase in glutamate uptake, the major release of trophic factors and better astrocytic coverage of cerebral blood vessels. The purpose of this review is to highlight the effects of exercise on brain function, emphasize the role of astrocytes in the healthy CNS, and provide an update for a better understanding of the effects of physical exercise in the modulation of astrocyte function.

Understanding the role of aerobic fitness, spatial learning, and hippocampal subfields in adolescent males

Physical exercise during adolescence, a critical developmental window, can facilitate neurogenesis in the dentate gyrus and astrogliogenesis in Cornu Ammonis (CA) hippocampal subfields of rats, and which have been associated with improved hippocampal dependent memory performance. Recent translational studies in humans also suggest that aerobic fitness is associated with hippocampal volume and better spatial memory during adolescence. However, associations between fitness, hippocampal subfield morphology, and learning capabilities in human adolescents remain largely unknown. Employing a translational study design in 34 adolescent males, we explored the relationship between aerobic fitness, hippocampal subfield volumes, and both spatial and verbal memory. Aerobic fitness, assessed by peak oxygen utilization on a high-intensity exercise test (VO2 peak), was positively associated with the volumetric enlargement of the hippocampal head, and the CA1 head region specifically. Larger CA1 volumes were also associated with spatial learning on a Virtual Morris Water Maze task and verbal learning on the Rey Auditory Verbal Learning Test, but not recall memory. In line with previous animal work, the current findings lend support for the long-axis specialization of the hippocampus in the areas of exercise and learning during adolescence.

Neurochemical and Cognitive Beneficial Effects of Moderate Physical Activity and Catechin in Aged Rats

A healthy aging process is a requirement for good life quality. A relationship between physical activity, the consumption of antioxidants and brain health has been stablished via the activation of pathways that reduce the harmful effects of oxidative stress, by inducing enzymes such as SIRT1, which is a protector of brain function. We analyzed the cognitive and neurochemical effects of applying physical exercise in elderly rats, alone or in combination with the antioxidant catechin. Several tests of spatial and episodic memory and motor coordination were evaluated. In addition, brain monoaminergic neurotransmitters and SIRT1 protein levels were assessed in the brains of the same rats. The results show that physical activity by itself improved age-related memory and learning deficits, correlating with the restoration of brain monoaminergic neurotransmitters and SIRT1 protein levels in the hippocampus. The administration of the antioxidant catechin along with the exercise program enhanced further the monoaminergic pathways, but not the other parameters studied. These results agree with previous reports revealing a neuroprotective effect of physical activity, probably based on its ability to improve the redox status of the brain, demonstrating that exercise at an advanced age, combined with the consumption of antioxidants, could produce favorable effects in terms of brain health.

Sensorimotor and Activity Psychosis-Risk (SMAP-R) Scale: An Exploration of Scale Structure With Replication and Validation

BACKGROUND

Sensorimotor abnormalities precede and predict the onset of psychosis. Despite the practical utility of sensorimotor abnormalities for early identification, prediction, and individualized medicine applications, there is currently no dedicated self-report instrument designed to capture these important behaviors. The current study assessed and validated a questionnaire designed for use in individuals at clinical high-risk for psychosis (CHR).

METHODS

The current study included both exploratory (n = 3009) and validation (n = 439) analytic datasets-that included individuals identified as meeting criteria for a CHR syndrome (n = 84)-who completed the novel Sensorimotor Abnormalities and Psychosis-Risk (SMAP-R) Scale, clinical interviews and a finger-tapping task. The structure of the scale and reliability of items were consistent across 2 analytic datasets. The resulting scales were assessed for discriminant validity across CHR, community sample non-psychiatric volunteer, and clinical groups.

RESULTS

The scale showed a consistent structure across 2 analytic datasets subscale structure. The resultant subscale structure was consistent with conceptual models of sensorimotor pathology in psychosis (coordination and dyskinesia) in both the exploratory and the validation analytic dataset. Further, these subscales showed discriminant, predictive, and convergent validity. The sensorimotor abnormality scales discriminated CHR from community sample non-psychiatric controls and clinical samples. Finally, these subscales predicted to risk calculator scores and showed convergent validity with sensorimotor performance on a finger-tapping task.

CONCLUSION

The SMAP-R scale demonstrated good internal, discriminant, predictive, and convergent validity, and subscales mapped on to conceptually relevant sensorimotor circuits. Features of the scale may facilitate widespread incorporation of sensorimotor screening into psychosis-risk research and practice.

The environmental enrichment model revisited: A translatable paradigm to study the stress of our modern lifestyle

Mounting evidence shows that physical activity, social interaction and sensorimotor stimulation provided by environmental enrichment (EE) exert several neurobehavioural effects traditionally interpreted as enhancements relative to standard housing (SH) conditions. However, this evidence rather indicates that SH induces many deficits, which could be ameliorated by exposing animals to an environment vaguely mimicking some features of their wild habitat. Rearing rodents in social isolation (SI) can aggravate such deficits, which can be restored by SH or EE. It is not surprising, therefore, that most preclinical stress models have included severe and unnatural stressors to produce a stress response prominent enough to be distinguishable from SH or SI-frequently used as control groups. Although current stress models induce a stress-related phenotype, they may fail to represent the stress of our urban lifestyle characterized by SI, poor housing and working environments, sedentarism, obesity and limited access to recreational activities and exercise. In the following review, we discuss the stress of living in urban areas and how exposures to and performing activities in green environments are stress relievers. Based on the commonalities between human and animal EE, we discuss how models of housing conditions (e.g., SI-SH-EE) could be adapted to study the stress of our modern lifestyle. The housing conditions model might be easy to implement and replicate leading to more translational results. It may also contribute to accomplishing some ethical commitments by promoting the refinement of procedures to model stress, diminishing animal suffering, enhancing animal welfare and eventually reducing the number of experimental animals needed.

Physical activity and aerobic fitness show different associations with brain processes underlying anticipatory selective visuospatial attention in adolescents

Current knowledge about the underlying brain processes of exercise-related benefits on executive functions and the specific contributions of physical activity and aerobic fitness during adolescence is inconclusive. We explored whether and how physical activity and aerobic fitness are associated with the oscillatory dynamics underlying anticipatory spatial attention. We studied whether the link between physical exercise level and cognitive control in adolescents is mediated by task-related oscillatory activity. Magnetoencephalographic alpha oscillations during a modified Posner's cueing paradigm were measured in 59 adolescents (37 females and 22 males, 12-17 years). Accelerometer-measured physical activity and aerobic fitness (20-m shuttle run test) were used to divide the sample into higher- and lower-performing groups. The interhemispheric alpha asymmetry during selective attention was larger in the high than in the low physical activity group, but there was no difference between the high and low aerobic fitness groups. Exploratory mediation analysis suggested that anticipatory interhemispheric asymmetry mediates the association between physical activity status and drift rate in the selective attention task. Higher physical activity was related to increased cue-induced asymmetry, which in turn was associated with less efficient processing of information. Behaviorally, more physically active males showed stronger dependence on the cue, while more fit females showed more efficient processing of information. Our findings suggest that physical activity may be associated with a neural marker of anticipatory attention in adolescents. These findings might help to explain the varying results regarding the association of physical activity and aerobic fitness with attention and inhibition in adolescents.

Working memory and hippocampal expression of BDNF, ARC, and P-STAT3 in rats: effects of diet and exercise

OBJECTIVES

Mounting evidence suggests diet and exercise influence learning and memory (LM). We compared a high-fat, high-sucrose Western diet (WD) to a plant-based, amylose/amylopectin blend, lower-fat diet known as the Daniel Fast (DF) in rats with and without regular aerobic exercise on a task of spatial working memory (WM).

METHODS

Rats were randomly assigned to the WD or DF at 6 weeks of age. Exercised rats (WD-E, DF-E) ran on a treadmill 3 times/week for 30 min while the sedentary rats did not (WD-S, DF-S). Rats adhered to these assignments for 12 weeks, inclusive of ab libitum food intake, after which mild food restriction was implemented to encourage responding during WM testing. For nine months, WM performance was assessed once daily, six days per week, after which hippocampal sections were collected for subsequent analysis of brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeletal protein (ARC), and signal transducer and activator of transcription 3 (P-STAT3, Tyr705).

RESULTS

DF-E rats exhibited the best DSA performance. Surprisingly, the WD-S group outperformed the WD-E group, but had significantly lower BDNF and ARC relative to the DF-S group, with a similar trend from the WD-E group. P-STAT3 expression was also significantly elevated in the WD-S group compared to both the DF-S and WD-E groups.

DISCUSSION

These results support previous research demonstrating negative effects of the WD on spatial LM, demonstrate the plant-based DF regimen combined with chronic aerobic exercise produces measurable WM and neuroprotective benefits, and suggest the need to carefully design exercise prescriptions to avoid over-stressing individuals making concurrent dietary changes.

Physical exercise promotes brain remodeling by regulating epigenetics, neuroplasticity and neurotrophins

Exercise has been shown to have beneficial effects on brain functions in humans and animals. Exercise can improve memory and learning in age-related neurodegenerative diseases. In animal models, physical exercise regulates epigenetics, promotes synaptic plasticity and hippocampal neurogenesis, regulates the expression levels of neurotrophic factors, and improves cognitive function. Therefore, exercise is very important for brain rehabilitation and remodeling. The purpose of this review is to explore the mechanisms by which exercise exerts positive effects on brain function. This knowledge implies that physical exercise can be used as a non-drug therapy for neurological diseases.

The Mechanism of Physical Activity-induced Amelioration of Parkinson's Disease: A Narrative Review

Physical activity, together with its ameliorative effects on Parkinson's disease (PD) symptoms, remains a relatively unappreciated factor which may be beneficial for the treatment outcome. Contemporary evidence supports the positive effects of non-pharmacological approaches to PD symptom management, in particular the effects of the exercise on both, motor and non-motor symptoms. The aim of the study was to review the mechanisms of exercise-induced amelioration of PD symptoms. Methods: Electronic databases (PubMed, Web of Science and Google Scholar) were searched using the following key words: "Parkinson and physical activity" OR "Parkinson disease and exercise" OR "Parkinson disease and lifestyle factors" OR "Parkinson disease and longevity". A total of 97 studies which investigated PD genetics and various forms of exercise and their etiologic impact on PD were reviewed. The studies were subdivided into four topic groups: 1) genetics of PD, 2) exercise and the brain, 3) physical activity and PD, 4) mind-body interventions, and discussed accordingly. Adequate levels of physical activity are associated with higher quality of life in PD patients. Physical activity may have protective and stimulatory effects for better functional efficiency in higher-level cognitive networks. It can also improve balance and motor functions by improving muscle strength. Given the etiologic evidence of the beneficial effects of physical activity on PD, albeit tentative, a concerted effort to elucidate the processes and outcomes of physical activity on ameliorating symptoms of PD must be undertaken.

The Contribution of Physical Exercise to Brain Resilience

Increasing attention has been given to understanding resilience to brain diseases, often described as brain or cognitive reserve. Among the protective factors for the development of resilience, physical activity/exercise has been considered to play an important role. Exercise is known to induce many positive effects on the brain. As such, exercise represents an important tool to influence neurodevelopment and shape the adult brain to react to life's challenges. Among many beneficial effects, exercise intervention has been associated with cognitive improvement and stress resilience in humans and animal models. Thus, a growing number of studies have demonstrated that exercise not only recovers or minimizes cognitive deficits by inducing better neuroplasticity and cognitive reserve but also counteracts brain pathology. This is evidenced before disease onset or after it has been established. In this review, we aimed to present encouraging data from current clinical and pre-clinical neuroscience research and discuss the possible biological mechanisms underlying the beneficial effects of physical exercise on resilience. We consider the implication of physical exercise for resilience from brain development to aging and for some neurological diseases. Overall, the literature indicates that brain/cognitive reserve built up by regular exercise in several stages of life, prepares the brain to be more resilient to cognitive impairment and consequently to brain pathology.

Influence of Cardiorespiratory Fitness on Risk of Dementia and Dementia Mortality: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

The purpose of this meta-analysis was to investigate the influence of cardiorespiratory fitness (CF) levels on dementia risk and dementia mortality. MEDLINE and EMBASE databases were used to search for eligible studies from January 1990 to September 2019. To be included, the study was required to be a prospective cohort study that provided CF measurements and indicated relative risk and confidence intervals for the associations between CF and dementia risk and mortality. A total of six studies were selected for this meta-analysis. Low-level CF was associated with nearly three times greater risk of dementia (2.93, 95% confidence interval [1.31, 6.57]; p < .05) compared with a high-level CF. Enhanced CF levels decreased the risk of dementia, and an increase of one metabolic equivalent of task in the CF level reduced the risk of dementia and dementia mortality. Maintaining more than 12 metabolic equivalents of task of CF level was required to substantially decrease dementia risk and dementia mortality.

Effects of whole-body vibration on motor function in patients with Parkinson’s disease: a systematic review and meta-analysis

Objective:

To review the effects of whole body vibration for patients with Parkinson’s disease.

Design:

Randomized clinical trials comparing whole body vibration with no vibration or conventional physical therapy for patients with Parkinson’s disease were searched up to July 31, 2019.

Results:

Seven studies with 196 patients were included for quantitative analysis. No significant difference was found between groups in motor score of unified Parkinson’s disease rating scale (UPDRS-III) (WMD [weighted mean difference] = −1.75, 95% CI, −5.40 to 1.90, I2 = 45.8%), functional reach test (SMD [standardized mean difference] = 0.21, 95% CI, −0.29 to 0.71; I2 = 0%), and other balance tests (including Berg balance test and Tinetti score) (SMD = 0.39, 95% CI, −0.01 to 0.80; I2 = 0%). No statistical difference was detected in walking velocity as well (WMD = −0.05, 95% CI, −0.17 to 0.06; I2 = 0%). In contrast, the pooled analysis from four studies on the Time Up and Go test showed favorable results for whole body vibration (WMD = −1.59, 95% CI, −2.90 to −0.28, I2 = 0%).

Conclusion:

Whole body vibration may not be beneficial over placebo or conventional physical therapy in overall motor function, balance, and walking velocity in patients with Parkinson’s disease. However, it might have positive effects on sit to stand transitions or turning.

Aerobic Fitness Unrelated to Acquisition of Spatial Relational Memory in College-Aged Adults

While compelling evidence indicates that poorer aerobic fitness relates to impairments in retrieving information from hippocampal-dependent memory, there is a paucity of research on how aerobic fitness relates to the acquisition of such relational information. Accordingly, the present investigation examined the association between aerobic fitness and the rate of encoding spatial relational memory-assessed using a maximal oxygen consumption test and a spatial configuration task-in a sample of 152 college-aged adults. The findings from this investigation revealed no association between aerobic fitness and the acquisition of spatial relational memory. These findings have implications for how aerobic fitness is characterized with regard to memory, such that aerobic fitness does not appear to relate to the rate of learning spatial-relational information; however, given previously reported evidence, aerobic fitness may be associated with a greater ability to recall relational information from memory.

Exercise reverses learning deficits induced by hippocampal injury by promoting neurogenesis

Hippocampal atrophy and cognitive decline are common sequelae of many neurodegenerative disorders, including stroke. To determine whether cognitive decline can be ameliorated by exercise-induced neurogenesis, C57BL/6 mice in which a unilateral hippocampal injury had been induced by injecting the vasoconstrictor endothelin-1 into their right hippocampus, were run voluntarily for 21 days on a running-wheel. We found the severe deficits in spatial learning, as detected by active place-avoidance task, following injury were almost completely restored in animals that ran whereas those that did not run showed no improvement. We show the increase in neurogenesis found in both the injured and contralateral hippocampi following running was responsible for the restoration of learning since bilateral ablation of newborn doublecortin (DCX)-positive neurons abrogated the cognitive improvement, whereas unilateral ablations of DCX-positive neurons did not prevent recovery, demonstrating that elevated neurogenesis in either the damaged or intact hippocampus is sufficient to reverse hippocampal injury-induced deficits.

Long-Term Running Exercise Delays Age-Related Changes in White Matter in Rats

Running exercise, one of the strategies to protect brain function, has positive effects on neurons and synapses in the cortex and hippocampus. However, white matter, as an important structure of the brain, is often overlooked, and the effects of long-term running exercise on white matter are unknown. Here, 14-month-old male Sprague–Dawley (SD) rats were divided into a middle-aged control group (18-month-old control group), an old control group (28-month-old control group), and a long-term runner group (28-month-old runner group). The rats in the runner group underwent a 14-month running exercise regime. Spatial learning ability was tested using the Morris water maze, and white matter volume, myelinated fiber parameters, total mature oligodendrocyte number, and white matter capillary parameters were investigated using stereological methods. The levels of growth factors related to nerve growth and vascular growth in peripheral blood and the level of neurite outgrowth inhibitor-A (Nogo-A) in white matter were measured using an enzyme-linked immunosorbent assay (ELISA). The present results indicated that long-term running exercise effectively delayed the age-related decline in spatial learning ability and the atrophy of white matter by protecting against age-related changes in myelinated fibers and oligodendrocytes in the white matter. Moreover, long-term running exercise prevented age-related changes in capillaries within white matter, which might be related to the protective effects of long-term exercise on aged white matter.

Diffusion tensor-MRI detects exercise-induced neuroplasticity in the hippocampal microstructure in mice

Background:

Despite considerable research on exercise-induced neuroplasticity in the brain, a major ongoing challenge in translating findings from animal studies to humans is that clinical and preclinical settings employ very different techniques.

Objective:

Here we aim to bridge this divide by using diffusion tensor imaging MRI (DTI), an advanced imaging technique commonly applied in human studies, in a longitudinal exercise study with mice.

Methods:

Wild-type mice were exercised using voluntary free-wheel running, and MRI scans were at baseline and after four weeks and nine weeks of running.

Results:

Both hippocampal volume and fractional anisotropy, a surrogate for microstructural directionality, significantly increased with exercise. In addition, exercise levels correlated with effect size. Histological analysis showed more PDGFRα+ oligodendrocyte precursor cells in the corpus callosum of running mice.

Conclusions:

These results provide compelling in vivo support for the concept that similar adaptive changes occur in the brains of mice and humans in response to exercise.

The Effect of Aerobic Exercise on Physical and Cognitive Outcomes in a Small Cohort of Outpatients with Schizophrenia

Background:

Schizophrenia (SCZ) is a severe, chronic illness characterized by psychotic symptoms and impairments in many cognitive domains. Dysregulation of brain derived neurotrophic factor (BDNF) is associated with the cognitive impairments seen in patients with SCZ. Given the growing literature supporting a positive effect of aerobic exercise on cognition in other populations, we hypothesized that a structured aerobic exercise program would improve cognitive and functional outcomes in subjects with SCZ, potentially mediated by increases in BDNF.

Methods:

The study was a small randomized parallel group clinical trial of subjects with SCZ comparing 12 weeks of aerobic exercise (AE) against control (CON) stretching and balance training. At Baseline, Week 12, and Week 20 we collected serum samples for analysis of brain derived neurotrophic factor (BDNF), and assessed functional, physical, and cognitive outcomes. Linear regression models were used to compare change scores between timepoints.

Results:

We randomized 21 subjects to AE and 17 to CON; however, only 9 AE and 6 CON completed their programs. Subjects in both groups were slower at the 400 m walk in Week 12 compared to Baseline, but the AE group had significantly less slowing than the CON group (B = –28.32, p = 0.011). Between Week 12 and Week 20, the AE group had a significantly greater change score on the Composite and Visual Learning Domain of the MATRICS Consensus Cognitive Battery (B = 5.11, p = 0.03; B = 13.96, p = 0.006).

Conclusion:

These results indicate that participation in a structured aerobic exercise paradigm may modestly blunt physical function decline and enhance cognitive function in individuals with SCZ.