Repetitive transcranial magnetic stimulation (rTMS) influences spatial cognition and modulates hippocampal structural synaptic plasticity in aging mice

Repetitive transcranial magnetic stimulation in Alzheimer's disease: effects on neural and synaptic rehabilitation

Alzheimer's disease is a neurodegenerative disease resulting from deficits in synaptic transmission and homeostasis. The Alzheimer's disease brain tends to be hyperexcitable and hypersynchronized, thereby causing neurodegeneration and ultimately disrupting the operational abilities in daily life, leaving patients incapacitated. Repetitive transcranial magnetic stimulation is a cost-effective, neuro-modulatory technique used for multiple neurological conditions. Over the past two decades, it has been widely used to predict cognitive decline; identify pathophysiological markers; promote neuroplasticity; and assess brain excitability, plasticity, and connectivity. It has also been applied to patients with dementia, because it can yield facilitatory effects on cognition and promote brain recovery after a neurological insult. However, its therapeutic effectiveness at the molecular and synaptic levels has not been elucidated because of a limited number of studies. This study aimed to characterize the neurobiological changes following repetitive transcranial magnetic stimulation treatment, evaluate its effects on synaptic plasticity, and identify the associated mechanisms. This review essentially focuses on changes in the pathology, amyloidogenesis, and clearance pathways, given that amyloid deposition is a major hypothesis in the pathogenesis of Alzheimer's disease. Apoptotic mechanisms associated with repetitive transcranial magnetic stimulation procedures and different pathways mediating gene transcription, which are closely related to the neural regeneration process, are also highlighted. Finally, we discuss the outcomes of animal studies in which neuroplasticity is modulated and assessed at the structural and functional levels by using repetitive transcranial magnetic stimulation, with the aim to highlight future directions for better clinical translations.

Microglia and Astrocytes Responses Contribute to Alleviating Inflammatory Damage by Repetitive Transcranial Magnetic Stimulation in Rats with Traumatic Brain Injury

Repetitive transcranial magnetic stimulation (rTMS) is a therapeutic strategy that shows promise in ameliorating the clinical sequelae following traumatic brain injury (TBI). These improvements are associated with neuroplastic changes in neurons and their synaptic connections. However, it has been hypothesized that rTMS may also modulate microglia and astrocytes, potentially potentiating their neuroprotective capabilities. This study aims to investigate the effects of high-frequency rTMS on microglia and astrocytes that may contribute to its neuroprotective effects. Feeney's weight-dropping method was used to establish rat models of moderate TBI. To evaluate the neuroprotective effect of high frequency rTMS on rats by observing the synaptic ultrastructure and the level of neuron apoptosis. The levels of several important inflammation-related proteins within microglia and astrocytes were assessed through immunofluorescence staining and western blot. Our findings demonstrate that injured neurons can be rescued through the modulation of microglia and astrocytes by rTMS. This modulation plays a key role in preserving the synaptic ultrastructure and inhibiting neuronal apoptosis. Among microglia, we observed that rTMS inhibited the levels of proinflammatory factors (CD16, IL-6 and TNF-α) and promoted the levels of anti-inflammatory factors (CD206, IL-10 and TNF-β). rTMS also reduced the levels of pyroptosis within microglia and pyroptosis-related proteins (NLRP3, Caspase-1, GSDMD, IL-1β and IL-18). Moreover, rTMS downregulated P75NTR expression and up-regulated IL33 expression in astrocytes. These findings suggest that regulation of microglia and astrocytes is the mechanism through which rTMS attenuates neuronal inflammatory damage after moderate TBI.

Recent Research Progress on the Use of Transcranial Magnetic Stimulation in the Treatment of Vascular Cognitive Impairment

Vascular Cognitive Impairment (VCI) is a condition where problems with brain blood vessels lead to a decline in cognitive abilities, commonly affecting the elderly and placing a significant burden on both patients and their families. Compared to medication and surgery, Transcranial Magnetic Stimulation (TMS) is a non-invasive treatment option with fewer risks and side effects, making it particularly suitable for elderly patients. TMS not only assesses the excitability and plasticity of the cerebral cortex, but its effectiveness in treating Vascular Cognitive Impairment (VCI) and its subtypes has also been validated in numerous clinical trials worldwide. However, there is still a lack of review on the physiological mechanisms of TMS treatment for VCI and its specific clinical application parameters. Therefore, this article initially provided a brief overview of the risk factors, pathological mechanisms, and classification of VCI. Next, the article explained the potential physiological mechanisms of TMS in treating VCI, particularly its role in promoting synaptic plasticity, regulating neurotransmitter balance, and improving the function of the default mode network. Additionally, The article also summarizes the application of rTMS in treating VCI and its subtypes, VCI-related sleep disorders, and the use of TMS in follow-up studies of VCI patients, providing empirical evidence for the clinical application of TMS and rTMS technologies.

Aberrant Hippocampal Development in Early-onset Mental Disorders and Promising Interventions: Evidence from a Translational Study

Early-onset mental disorders are associated with disrupted neurodevelopmental processes during adolescence. The methylazoxymethanol acetate (MAM) animal model, in which disruption in neurodevelopmental processes is induced, mimics the abnormal neurodevelopment associated with early-onset mental disorders from an etiological perspective. We conducted longitudinal structural magnetic resonance imaging (MRI) scans during childhood, adolescence, and adulthood in MAM rats to identify specific brain regions and critical windows for intervention. Then, the effect of repetitive transcranial magnetic stimulation (rTMS) intervention on the target brain region during the critical window was investigated. In addition, the efficacy of this intervention paradigm was tested in a group of adolescent patients with early-onset mental disorders (diagnosed with major depressive disorder or bipolar disorder) to evaluate its clinical translational potential. The results demonstrated that, compared to the control group, the MAM rats exhibited significantly lower striatal volume from childhood to adulthood (all P <0.001). In contrast, the volume of the hippocampus did not show significant differences during childhood (P >0.05) but was significantly lower than the control group from adolescence to adulthood (both P <0.001). Subsequently, rTMS was applied to the occipital cortex, which is anatomically connected to the hippocampus, in the MAM models during adolescence. The MAM-rTMS group showed a significant increase in hippocampal volume compared to the MAM-sham group (P <0.01), while the volume of the striatum remained unchanged (P >0.05). In the clinical trial, adolescents with early-onset mental disorders showed a significant increase in hippocampal volume after rTMS treatment compared to baseline (P <0.01), and these volumetric changes were associated with improvement in depressive symptoms (r = - 0.524, P = 0.018). These findings highlight the potential of targeting aberrant hippocampal development during adolescence as a viable intervention for early-onset mental disorders with neurodevelopmental etiology as well as the promise of rTMS as a therapeutic approach for mitigating aberrant neurodevelopmental processes and alleviating clinical symptoms.

Effects of repetitive transcranial magnetic stimulation in children and young people with psychiatric disorders: a systematic review

Repetitive transcranial magnetic stimulation (rTMS) has demonstrated benefits in adults with psychiatric disorders, but its clinical utility in children and young people (CYP) is unclear. This PRISMA systematic review used published and ongoing studies to examine the effects of rTMS on disorder-specific symptoms, mood and neurocognition in CYP with psychiatric disorders. We searched Medline via PubMed, Embase, PsychINFO via OVID, and Clinicaltrials.gov up to July 2023. Eligible studies involved multiple-session (i.e., treatment) rTMS in CYP (≤ 25 years-old) with psychiatric disorders. Two independent raters assessed the eligibility of studies and extracted data using a custom-built form. Out of 78 eligible studies (participant N = 1389), the majority (k = 54; 69%) reported an improvement in at least one outcome measure of disorder-specific core symptoms. Some studies (k = 21) examined rTMS effects on mood or neurocognition,: findings were largely positive. Overall, rTMS was well-tolerated with minimal side-effects. Of 17 ongoing or recently completed studies, many are sham-controlled RCTs with better blinding techniques and a larger estimated participant enrolment. Findings provide encouraging evidence for rTMS-related improvements in disorder-specific symptoms in CYP with different psychiatric disorders. However, in terms of both mood (for conditions other than depression) and neurocognitive outcomes, evidence is limited. Importantly, rTMS is well-tolerated and safe. Ongoing studies appear to be of improved methodological quality; however, future studies should broaden outcome measures to more comprehensively assess the effects of rTMS and develop guidance on dosage (i.e., treatment regimens).

Low-frequency rTMS modulated the excitability and high-frequency firing in hippocampal neurons of the Alzheimer's disease mouse model

Repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, holds potential for applications in the treatment of Alzheimer's disease (AD). This study aims to compare the therapeutic effects of rTMS at different frequencies on Alzheimer's disease and explore the alterations in neuronal electrophysiological properties throughout this process. APP/PS1 AD mice were subjected to two rTMS treatments at 0.5 Hz and 20 Hz, followed by assessments of therapeutic outcomes through the Novel Object Recognition (NOR) and Morris Water Maze (MWM) tests. Following this, whole-cell patch-clamp techniques were used to record action potential, voltage-gated sodium channel currents, and voltage-gated potassium channel currents in dentate gyrus granule neurons. The results show that AD mice exhibit significant cognitive decline compared to normal mice, along with a pronounced reduction in neuronal excitability and ion channel activity. Both frequencies of rTMS treatment partially reversed these changes, demonstrating similar therapeutic efficacy. Furthermore, the investigation indicates that low-frequency magnetic stimulation inhibited the concentrated firing of early action potentials in AD.

Repetitive transcranial magnetic stimulation ameliorates cognitive deficits in mice with radiation-induced brain injury by attenuating microglial pyroptosis and promoting neurogenesis via BDNF pathway

BACKGROUND

Radiation-induced brain injury (RIBI) is a common and severe complication during radiotherapy for head and neck tumor. Repetitive transcranial magnetic stimulation (rTMS) is a novel and non-invasive method of brain stimulation, which has been applied in various neurological diseases. rTMS has been proved to be effective for treatment of RIBI, while its mechanisms have not been well understood.

METHODS

RIBI mouse model was established by cranial irradiation, K252a was daily injected intraperitoneally to block BDNF pathway. Immunofluorescence staining, immunohistochemistry and western blotting were performed to examine the microglial pyroptosis and hippocampal neurogenesis. Behavioral tests were used to assess the cognitive function and emotionality of mice. Golgi staining was applied to observe the structure of dendritic spine in hippocampus.

RESULTS

rTMS significantly promoted hippocampal neurogenesis and mitigated neuroinflammation, with ameliorating pyroptosis in microglia, as well as downregulation of the protein expression level of NLRP3 inflammasome and key pyroptosis factor Gasdermin D (GSDMD). BDNF signaling pathway might be involved in it. After blocking BDNF pathway by K252a, a specific BDNF pathway inhibitor, the neuroprotective effect of rTMS was markedly reversed. Evaluated by behavioral tests, the cognitive dysfunction and anxiety-like behavior were found aggravated with the comparison of mice in rTMS intervention group. Moreover, the level of hippocampal neurogenesis was found to be attenuated, the pyroptosis of microglia as well as the levels of GSDMD, NLRP3 inflammasome and IL-1β were upregulated.

CONCLUSION

Our study indicated that rTMS notably ameliorated RIBI-induced cognitive disorders, by mitigating pyroptosis in microglia and promoting hippocampal neurogenesis via mediating BDNF pathway.

Chronic Pain-Related Cognitive Deficits: Preclinical Insights into Molecular, Cellular, and Circuit Mechanisms

Cognitive impairment is a common comorbidity of chronic pain, significantly disrupting patients' quality of life. Despite this comorbidity being clinically recognized, the underlying neuropathological mechanisms remain unclear. Recent preclinical studies have focused on the fundamental mechanisms underlying the coexistence of chronic pain and cognitive decline. Pain chronification is accompanied by structural and functional changes in the neural substrate of cognition. Based on the developments in electrophysiology and optogenetics/chemogenetics, we summarized the relevant neural circuits involved in pain-induced cognitive impairment, as well as changes in connectivity and function in brain regions. We then present the cellular and molecular alternations related to pain-induced cognitive impairment in preclinical studies, mainly including modifications in neuronal excitability and structure, synaptic plasticity, glial cells and cytokines, neurotransmitters and other neurochemicals, and the gut-brain axis. Finally, we also discussed the potential treatment strategies and future research directions.

Cognitive and Neuropathophysiological Outcomes of Gamma-tACS in Dementia: A Systematic Review

Despite the numerous pharmacological interventions targeting dementia, no disease-modifying therapy is available, and the prognosis remains unfavorable. A promising perspective involves tackling high-frequency gamma-band (> 30 Hz) oscillations involved in hippocampal-mediated memory processes, which are impaired from the early stages of typical Alzheimer's Disease (AD). Particularly, the positive effects of gamma-band entrainment on mouse models of AD have prompted researchers to translate such findings into humans using transcranial alternating current stimulation (tACS), a methodology that allows the entrainment of endogenous cortical oscillations in a frequency-specific manner. This systematic review examines the state-of-the-art on the use of gamma-tACS in Mild Cognitive Impairment (MCI) and dementia patients to shed light on its feasibility, therapeutic impact, and clinical effectiveness. A systematic search from two databases yielded 499 records resulting in 10 included studies and a total of 273 patients. The results were arranged in single-session and multi-session protocols. Most of the studies demonstrated cognitive improvement following gamma-tACS, and some studies showed promising effects of gamma-tACS on neuropathological markers, suggesting the feasibility of gamma-tACS in these patients anyhow far from the strong evidence available for mouse models. Nonetheless, the small number of studies and their wide variability in terms of aims, parameters, and measures, make it difficult to draw firm conclusions. We discuss results and methodological limitations of the studies, proposing possible solutions and future avenues to improve research on the effects of gamma-tACS on dementia.

Continuous high-frequency repetitive transcranial magnetic stimulation at extremely low intensity affects exploratory behavior and spatial cognition in mice

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has been shown to be effective for cognitive intervention. However, whether HF-rTMS with extremely low intensity could influence cognitive functions is still under investigation. The present study systematically investigated the effects of continuous 40 Hz and 10 Hz rTMS on cognition in young adult mice at extremely low intensity (10 mT and 1 mT) for 11 days (30 min/day). Cognitive functions were assessed using diverse behavioral tasks, including the open field, Y-maze, and Barnes maze paradigms. We found that 40 Hz rTMS significantly impaired exploratory behavior and spatial memory in both 10 mT and 1 mT conditions. In addition, 40 Hz rTMS induced remarkably different effects on exploratory behavior between 10 mT and 1mT, compared to 10 Hz stimulation. Our results indicate that extremely low intensity rTMS can significantly alter cognitive performance depending on intensity and frequency, shedding light on the understanding of the mechanism of rTMS effects.

The association of total pulses with the efficacy of repetitive transcranial magnetic stimulation for treatment-resistant major depression: A dose-response meta-analysis

AIM

This study aimed to examine dose-effects of total pulses on improvement of depressive symptoms in patients with treatment-resistant depression (TRD) receiving repetitive transcranial magnetic stimulation (rTMS) over the left dorsal lateral prefrontal cortex (DLPFC).

MATERIALS AND METHODS

The MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, PsycINFO, and ClinicalTrial.gov databases were systematically searched. We included randomized, double-blind, placebo-controlled trials (RCT) that used rTMS over left DLPFC in patients with TRD. Excluded studies were non-TRD, non-RCTs, or combined other brain stimulation interventions. The outcome of interest was the difference between rTMS arms and sham controls in improvement of depressive symptoms in a dose-response manner. A random-effects meta-analysis and dose-response meta-analysis(DRMA) was used to examine antidepressant efficacy of rTMS and association with total pulses.

RESULTS

We found that rTMS over left DLPFC is superior to sham controls (reported as standardized mean difference[SMD] with 95% confidence interval: 0.77; 0.56-0.98). The best-fitting model of DRMA was bell-shaped (estimated using restricted cubic spline model; R2 =0.42), indicating that higher doses (>26,660 total pulses) were not associated with increased improvement of depressive symptoms. Stimulation frequency(R2 =0.53) and age(R2 =0.51) were significant moderators for the dose-response curve. Furthermore, 15-20 Hz rTMS was superior to 10 Hz rTMS (0.61, 0.15-1.10) when combining all doses.

CONCLUSIONS

Our findings suggest higher doses(total pulses) of rTMS were not always associated with increased improvement of depressive symptoms in patients with TRD, and that the dose-response relationship was moderated by stimulation frequency and age. These associations emphasize the importance of determining dosing parameters to achieve maximum efficacy.

Magnetic Stimulation as a Therapeutic Approach for Brain Modulation and Repair: Underlying Molecular and Cellular Mechanisms

Neurological and psychiatric diseases generally have no cure, so innovative non-pharmacological treatments, including non-invasive brain stimulation, are interesting therapeutic tools as they aim to trigger intrinsic neural repair mechanisms. A common brain stimulation technique involves the application of pulsed magnetic fields to affected brain regions. However, investigations of magnetic brain stimulation are complicated by the use of many different stimulation parameters. Magnetic brain stimulation is usually divided into two poorly connected approaches: (1) clinically used high-intensity stimulation (0.5-2 Tesla, T) and (2) experimental or epidemiologically studied low-intensity stimulation (μT-mT). Human tests of both approaches are reported to have beneficial outcomes, but the underlying biology is unclear, and thus optimal stimulation parameters remain ill defined. Here, we aim to bring together what is known about the biology of magnetic brain stimulation from human, animal, and in vitro studies. We identify the common effects of different stimulation protocols; show how different types of pulsed magnetic fields interact with nervous tissue; and describe cellular mechanisms underlying their effects-from intracellular signalling cascades, through synaptic plasticity and the modulation of network activity, to long-term structural changes in neural circuits. Recent advances in magneto-biology show clear mechanisms that may explain low-intensity stimulation effects in the brain. With its large breadth of stimulation parameters, not available to high-intensity stimulation, low-intensity focal magnetic stimulation becomes a potentially powerful treatment tool for human application.

Repetitive transcranial magnetic stimulation (rTMS) triggers dose-dependent homeostatic rewiring in recurrent neuronal networks

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used to induce neuronal plasticity in healthy individuals and patients. Designing effective and reproducible rTMS protocols poses a major challenge in the field as the underlying biomechanisms of long-term effects remain elusive. Current clinical protocol designs are often based on studies reporting rTMS-induced long-term potentiation or depression of synaptic transmission. Herein, we employed computational modeling to explore the effects of rTMS on long-term structural plasticity and changes in network connectivity. We simulated a recurrent neuronal network with homeostatic structural plasticity among excitatory neurons, and demonstrated that this mechanism was sensitive to specific parameters of the stimulation protocol (i.e., frequency, intensity, and duration of stimulation). Particularly, the feedback-inhibition initiated by network stimulation influenced the net stimulation outcome and hindered the rTMS-induced structural reorganization, highlighting the role of inhibitory networks. These findings suggest a novel mechanism for the lasting effects of rTMS, i.e., rTMS-induced homeostatic structural plasticity, and highlight the importance of network inhibition in careful protocol design, standardization, and optimization of stimulation.

Association between genetic polymorphisms of synaptophysin (SYP) gene and attention deficit hyperactivity disorder in Korean subjects

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a common childhood neurodevelopmental disorder, and the prevalence of ADHD among Korean children has attained about 8.5%. Various genetic factors can contribute to the etiology of the disease. Synaptophysin (SYP) regulates neurotransmitter release and synaptic plasticity. According to previous studies, several genetic polymorphisms on SYP were risk factors for ADHD.

OBJECTIVE

We investigated the effect of the SYP gene polymorphisms (rs2293945 and rs3817678) on ADHD in Korean children.

METHODS

In this study, we examined the case-control study in 150 ADHD cases and 322 controls. The genotyping of SYP gene polymorphisms was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

Significant associations in the genotype and genetic models of SYP rs2293945 polymorphism between girls with ADHD and control girls were found. The girls with ADHD having the C/T genotype were significantly associated with ADHD. In the dominant model of rs3817678, C/T + T/T genotypes were significantly associated with ADHD. The haplotype analyses showed significant associations from haplotypes of rs2293945 T-rs3817678 G and rs2293945 C-rs3817678 A.

CONCLUSION

Our results imply that the SYP rs2293945 C/T polymorphism in female participants may provide a possible effect on the genetic etiology of ADHD.

Repetitive Transcranial Magnetic Stimulation Reduces Depressive-like Behaviors, Modifies Dendritic Plasticity, and Generates Global Epigenetic Changes in the Frontal Cortex and Hippocampus in a Rodent Model of Chronic Stress

Depression is the most common affective disorder worldwide, accounting for 4.4% of the global population, a figure that could increase in the coming decades. In depression, there exists a reduction in the availability of dendritic spines in the frontal cortex (FC) and hippocampus (Hp). In addition, histone modification and DNA methylation are also dysregulated epigenetic mechanisms in depression. Repetitive transcranial magnetic stimulation (rTMS) is a technique that is used to treat depression. However, the epigenetic mechanisms of its therapeutic effect are still not known. Therefore, in this study, we evaluated the antidepressant effect of 5 Hz rTMS and examined its effect on dendritic remodeling, immunoreactivity of synapse proteins, histone modification, and DNA methylation in the FC and Hp in a model of chronic mild stress. Our data indicated that stress generated depressive-like behaviors and that rTMS reverses this effect, romotes the formation of dendritic spines, and favors the presynaptic connection in the FC and DG (dentate gyrus), in addition to increasing histone H3 trimethylation and DNA methylation. These results suggest that the antidepressant effect of rTMS is associated with dendritic remodeling, which is probably regulated by epigenetic mechanisms. These data are a first approximation of the impact of rTMS at the epigenetic level in the context of depression. Therefore, it is necessary to analyze in future studies as to which genes are regulated by these mechanisms, and how they are associated with the neuroplastic modifications promoted by rTMS.

Current evidence, clinical applications, and future directions of transcranial magnetic stimulation as a treatment for ischemic stroke

Transcranial magnetic stimulation (TMS) is a non-invasive brain neurostimulation technique that can be used as one of the adjunctive treatment techniques for neurological recovery after stroke. Animal studies have shown that TMS treatment of rats with middle cerebral artery occlusion (MCAO) model reduced cerebral infarct volume and improved neurological dysfunction in model rats. In addition, clinical case reports have also shown that TMS treatment has positive neuroprotective effects in stroke patients, improving a variety of post-stroke neurological deficits such as motor function, swallowing, cognitive function, speech function, central post-stroke pain, spasticity, and other post-stroke sequelae. However, even though numerous studies have shown a neuroprotective effect of TMS in stroke patients, its possible neuroprotective mechanism is not clear. Therefore, in this review, we describe the potential mechanisms of TMS to improve neurological function in terms of neurogenesis, angiogenesis, anti-inflammation, antioxidant, and anti-apoptosis, and provide insight into the current clinical application of TMS in multiple neurological dysfunctions in stroke. Finally, some of the current challenges faced by TMS are summarized and some suggestions for its future research directions are made.

Transcranial Electromagnetic Wave Treatment: A Fountain of Healthy Longevity?

Most diseases of older age have as their common denominator a dysfunctional immune system, wherein a low, chronic level of inflammation is present due to an imbalance of pro-inflammatory cytokines over anti-inflammatory cytokines that develops during aging ("inflamm-aging"). A gerotherapeutic that can restore the immune balance to that shared by young/middle-aged adults and many centenarians could reduce the risk of those age-related diseases and increase healthy longevity. In this perspectives paper, we discuss potential longevity interventions that are being evaluated and compare them to a novel gerotherapeutic currently being evaluated in humans-Transcranial Electromagnetic Wave Treatment (TEMT). TEMT is provided non-invasively and safety through a novel bioengineered medical device-the MemorEM-that allows for near complete mobility during in-home treatments. Daily TEMT to mild/moderate Alzheimer's Disease (AD) patients over a 2-month period rebalanced 11 of 12 cytokines in blood back to that of normal aged adults. A very similar TEMT-induced rebalancing of cytokines occurred in the CSF/brain for essentially all seven measurable cytokines. Overall inflammation in both blood and brain was dramatically reduced by TEMT over a 14-27 month period, as measured by C-Reactive Protein. In these same AD patients, a reversal of cognitive impairment was observed at 2 months into treatment, while cognitive decline was stopped over a 2½ year period of TEMT. Since most age-related diseases have the commonality of immune imbalance, it is reasonable to postulate that TEMT could rebalance the immune system in many age-related diseases as it appears to do in AD. We propose that TEMT has the potential to reduce the risk/severity of age-related diseases by rejuvenating the immune system to a younger age, resulting in reduced brain/body inflammation and a substantial increase in healthy longevity.

Intermittent Theta Burst Stimulation Improves Motor and Behavioral Dysfunction through Modulation of NMDA Receptor Subunit Composition in Experimental Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder characterized by the progressive degeneration of the dopaminergic system, leading to a variety of motor and nonmotor symptoms. The currently available symptomatic therapy loses efficacy over time, indicating the need for new therapeutic approaches. Repetitive transcranial magnetic stimulation (rTMS) has emerged as one of the potential candidates for PD therapy. Intermittent theta burst stimulation (iTBS), an excitatory protocol of rTMS, has been shown to be beneficial in several animal models of neurodegeneration, including PD. The aim of this study was to investigate the effects of prolonged iTBS on motor performance and behavior and the possible association with changes in the NMDAR subunit composition in the 6-hydroxydopamine (6-OHDA)-induced experimental model of PD. Two-month-old male Wistar rats were divided into four groups: controls, 6-OHDA rats, 6-OHDA + iTBS protocol (two times/day/three weeks) and the sham group. The therapeutic effect of iTBS was evaluated by examining motor coordination, balance, spontaneous forelimb use, exploratory behavior, anxiety-like, depressive/anhedonic-like behavior and short-term memory, histopathological changes and changes at the molecular level. We demonstrated the positive effects of iTBS at both motor and behavioral levels. In addition, the beneficial effects were reflected in reduced degeneration of dopaminergic neurons and a subsequent increase in the level of DA in the caudoputamen. Finally, iTBS altered protein expression and NMDAR subunit composition, suggesting a sustained effect. Applied early in the disease course, the iTBS protocol may be a promising candidate for early-stage PD therapy, affecting motor and nonmotor deficits.

rTMS treatment for abrogating intracerebral hemorrhage-induced brain parenchymal metabolite clearance dysfunction in male mice by regulating intracranial lymphatic drainage

BACKGROUND

The discovery of the glymphatic system and meningeal lymphatic vessels challenged the traditional view regarding the lack of a lymphatic system in the central nervous system. It is now known that the intracranial lymphatic system plays an important role in fluid transport, macromolecule uptake, and immune cell trafficking. Studies have also shown that the function of the intracranial lymphatic system is significantly associated with neurological diseases; for example, an impaired intracranial lymphatic system can lead to Tau deposition and an increased lymphocyte count in the brain tissue of mice with subarachnoid hemorrhage.

METHODS

In this study, we assessed the changes in the intracranial lymphatic system after intracerebral hemorrhage and the regulatory effects of repeated transcranial magnetic stimulation on the glymphatic system and meningeal lymphatic vessels in an intracerebral hemorrhage (ICH) model of male mice. Experimental mice were divided into three groups: Sham, ICH, and ICH + repeated transcranial magnetic stimulation (rTMS). Three days after ICH, mice in the ICH+rTMS group were subjected to rTMS daily for 7 days. Thereafter, the function of the intracranial lymphatic system, clearance of RITC-dextran and FITC-dextran, and neurological functions were evaluated.

RESULTS

Compared with the Sham group, the ICH group had an impaired glymphatic system. Importantly, rTMS treatment could improve intracranial lymphatic system function as well as behavioral functions and enhance the clearance of parenchymal RITC-dextran and FITC-dextran after ICH.

CONCLUSION

Our results indicate that rTMS can abrogate ICH-induced brain parenchymal metabolite clearance dysfunction by regulating intracranial lymphatic drainage.

Repetitive transcranial magnetic stimulation (rTMS) triggers dose-dependent homeostatic rewiring in recurrent neuronal networks

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used to induce neuronal plasticity in healthy individuals and patients. Designing effective and reproducible rTMS protocols poses a major challenge in the field as the underlying biomechanisms remain elusive. Current clinical protocol designs are often based on studies reporting rTMS-induced long-term potentiation or depression of synaptic transmission. Herein, we employed computational modeling to explore the effects of rTMS on long-term structural plasticity and changes in network connectivity. We simulated a recurrent neuronal network with homeostatic structural plasticity between excitatory neurons, and demonstrated that this mechanism was sensitive to specific parameters of the stimulation protocol (i.e., frequency, intensity, and duration of stimulation). The feedback-inhibition initiated by network stimulation influenced the net stimulation outcome and hindered the rTMS-induced homeostatic structural plasticity, highlighting the role of inhibitory networks. These findings suggest a novel mechanism for the lasting effects of rTMS, i.e., rTMS-induced homeostatic structural plasticity, and highlight the importance of network inhibition in careful protocol design, standardization, and optimization of stimulation.

Low frequency repetitive transcranial magnetic stimulation promotes plasticity of the visual cortex in adult amblyopic rats

The decline of visual plasticity restricts the recovery of visual functions in adult amblyopia. Repetitive transcranial magnetic stimulation (rTMS) has been shown to be effective in treating adult amblyopia. However, the underlying mechanisms of rTMS on visual cortex plasticity remain unclear. In this study, we found that low-frequency rTMS reinstated the amplitude of visual evoked potentials, but did not influence the impaired depth perception of amblyopic rats. Furthermore, the expression of synaptic plasticity genes and the number of dendritic spines were significantly higher in amblyopic rats which received rTMS when compared with amblyopic rats which received sham stimulation, with reduced level of inhibition and perineuronal nets in visual cortex, as observed via molecular and histological investigations. The results provide further evidence that rTMS enhances functional recovery and visual plasticity in an adult amblyopic animal model.

Transcranial Magnetic Stimulation in Disorders of Consciousness: An Update and Perspectives

Disorders of consciousness (DOC) is a state in which consciousness is affected by brain injuries, leading to dysfunction in vigilance, awareness, and behavior. DOC encompasses coma, vegetative state, and minimally conscious state based on neurobehavioral function. Currently, DOC is one of the most common neurological disorders with a rapidly increasing incidence worldwide. Therefore, DOC not only impacts the lives of individuals and their families but is also becoming a serious public health threat. Repetitive transcranial magnetic stimulation (rTMS) can stimulate electrical activity using a pulsed magnetic field in the brain, with great value in the treatment of chronic pain, neurological diseases, and mental illnesses. However, the clinical application of rTMS in patients with DOC is debatable. Herein, we report the recent main findings of the clinical therapeutics of rTMS for DOC, including its efficacy and possible mechanisms. In addition, we discuss the potential key parameters (timing, location, frequency, strength, and secession of rTMS applications) that affect the therapeutic efficiency of rTMS in patients with DOC. This review may help develop clinical guidelines for the therapeutic application of rTMS in DOC.

Therapeutic non-invasive brain treatments in Alzheimer's disease: recent advances and challenges

Alzheimer's disease (AD) is one of the major neurodegenerative diseases and the most common form of dementia. Characterized by the loss of learning, memory, problem-solving, language, and other thinking abilities, AD exerts a detrimental effect on both patients' and families' quality of life. Although there have been significant advances in understanding the mechanism underlying the pathogenesis and progression of AD, there is no cure for AD. The failure of numerous molecular targeted pharmacologic clinical trials leads to an emerging research shift toward non-invasive therapies, especially multiple targeted non-invasive treatments. In this paper, we reviewed the advances of the most widely studied non-invasive therapies, including photobiomodulation (PBM), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and exercise therapy. Firstly, we reviewed the pathological changes of AD and the challenges for AD studies. We then introduced these non-invasive therapies and discussed the factors that may affect the effects of these therapies. Additionally, we review the effects of these therapies and the possible mechanisms underlying these effects. Finally, we summarized the challenges of the non-invasive treatments in future AD studies and clinical applications. We concluded that it would be critical to understand the exact underlying mechanisms and find the optimal treatment parameters to improve the translational value of these non-invasive therapies. Moreover, the combined use of non-invasive treatments is also a promising research direction for future studies and sheds light on the future treatment or prevention of AD.

Exposure to static magnetic field facilitates selective attention and neuroplasticity in rats

Static magnetic fields (SMF) have neuroprotective and behavioral effects in rats, however, little is known about the effects of SMF on cognition, motor function and the underlying neurochemical mechanisms. In this study, we focused on the effects of short-term (5~10d) and long-term (13~38d) SMF exposure on selective attention and motor coordination of rats, as well as associated alterations in expression level of neuroplasticity-related structural proteins and cryptochrome (CRY1) protein in the cortex, striatum and ventral midbrain. The results showed that 6 d SMF exposure significantly enhanced selective attention without affecting locomotor activity in open field. All SMF exposures non-significantly enhanced motor coordination (Rotarod test). Neurochemical analysis demonstrated that 5d SMF exposure increased the expression of cortical and striatal CRY1 and synapsin-1 (SYN1), striatal total synapsins (SYN), and synaptophysin (SYP), growth associated protein-43 (GAP43) and post-synaptic density protein-95 (PSD95) in the ventral midbrain. Exposure to SMF for 14d increased PSD95 level in the ventral midbrain while longer SMF exposure elevated the levels of PSD95 in the cortex, SYN and SYN1 in all the examined brain areas. The increased expression of cortical and striatal CRY1and SYN1 correlated with the short-lasting effect of SMF on improving selective attention. Collectively, SMF's effect on selective attention attenuated following longer exposure to SMF whereas its effects on neuroplasticity-related structural biomarkers were time- and brain area-dependent, with some protein levels increasing with longer time exposure. These findings suggest a potential use of SMF for treatment of neurological diseases in which selective attention or neuroplasticity is impaired.

High-frequency repetitive transcranial magnetic stimulation improves spatial episodic learning and memory performance by regulating brain plasticity in healthy rats

Background

Repetitive transcranial magnetic stimulation (rTMS) is an effective way to stimulate changes in structural and functional plasticity, which is a part of learning and memory. However, to our knowledge, rTMS-induced specific activity and neural plasticity in different brain regions that affect cognition are not fully understood; nor are its mechanisms. Therefore, we aimed to investigate rTMS-induced cognition-related neural plasticity changes and their mechanisms in different brain regions.

Methods

A total of 30 healthy adult rats were randomly divided into the control group and the rTMS group (n = 15 rats per group). The rats in the control and the rTMS group received either 4 weeks of sham or high-frequency rTMS (HF-rTMS) over the prefrontal cortex (PFC). Cognitive function was detected by Morris water maze. Functional imaging was acquired by resting-state functional magnetic resonance imaging (rs-fMRI) before and after rTMS. The protein expressions of BDNF, TrkB, p-Akt, Akt, NR1, NR2A, and NR2B in the PFC, hippocampus, and primary motor cortex (M1) were detected by Western blot following rTMS.

Results

After 4 weeks of rTMS, the cognitive ability of healthy rats who underwent rTMS showed a small but significant behavioral improvement in spatial episodic learning and memory performance. Compared with the pre-rTMS or the control group, rats in the rTMS group showed increased regional homogeneity (ReHo) in multiple brain regions in the interoceptive/default mode network (DMN) and cortico-striatal-thalamic network, specifically the bilateral PFC, bilateral hippocampus, and the left M1. Western blot analyses showed that rTMS led to a significant increase in the expressions of N-methyl-D-aspartic acid (NMDA) receptors, including NR1, NR2A, and NR2B in the PFC, hippocampus, and M1, as well as an upregulation of BDNF, TrkB, and p-Akt in these three brain regions. In addition, the expression of NR1 in these three brain regions correlated with rTMS-induced cognitive improvement.

Conclusion

Overall, these data suggested that HF-rTMS can enhance cognitive performance through modulation of NMDA receptor-dependent brain plasticity.

5 Hz of repetitive transcranial magnetic stimulation improves cognition and induces modifications in hippocampal neurogenesis in adult female Swiss Webster mice

Adult hippocampal neurogenesis is regulated by several stimuli to promote the creation of a reserve that may facilitate coping with environmental challenges. In this regard, repetitive transcranial magnetic stimulation (rTMS), a neuromodulation therapy, came to our attention because in clinical studies it reverts behavioral and cognitive alterations related to changes in brain plasticity. Some preclinical studies emphasize the need to understand the underlying mechanism of rTMS to induce behavioral modifications. In this study, we investigated the effects of rTMS on cognition, neurogenic-associated modifications, and neuronal activation in the hippocampus of female Swiss Webster mice. We applied 5 Hz of rTMS twice a day for 14 days. Three days later, mice were exposed to the behavioral battery. Then, brains were collected and immunostained for Ki67-positive cells, doublecortin-positive (DCX+)-cells, calbindin, c-Fos and FosB/Delta-FosB in the dentate gyrus. Also, we analyzed mossy fibers and CA3 with calbindin immunostaining. Mice exposed to rTMS exhibited cognitive improvement, an increased number of proliferative cells, DCX cells, DCX cells with complex dendrite morphology, c-Fos and immunoreactivity of FosB/Delta-FosB in the granular cell layer. The volume of the granular cell layer, mossy fibers and CA3 in rTMS mice also increased. Interestingly, cognitive improvement correlated with DCX cells with complex dendrite morphology. Also, those DCX cells and calbindin immunoreactivity correlated with c-Fos in the granular cell layer. Our results suggest that 5 Hz of rTMS applied twice a day modify cell proliferation, doublecortin cells, mossy fibers and enhance cognitive behavior in healthy female Swiss Webster mice.

Smart Device-Driven Corticolimbic Plasticity in Cognitive–Emotional Restructuring of Space-Related Neuropsychiatric Disease and Injury

Escalating government and commercial efforts to plan and deploy viable manned near-to-deep solar system exploration and habitation over the coming decades now drives next-generation space medicine innovations. The application of cutting-edge precision medicine, such as brain stimulation techniques, provides powerful clinical and field/flight situation methods to selectively control vagal tone and neuroendocrine-modulated corticolimbic plasticity, which is affected by prolonged cosmic radiation exposure, social isolation or crowding, and weightlessness in constricted operational non-terran locales. Earth-based clinical research demonstrates that brain stimulation approaches may be combined with novel psychotherapeutic integrated memory structure rationales for the corrective reconsolidation of arousing or emotional experiences, autobiographical memories, semantic schema, and other cognitive structures to enhance neuropsychiatric patient outcomes. Such smart cotherapies or countermeasures, which exploit natural, pharmaceutical, and minimally invasive neuroprosthesis-driven nervous system activity, may optimize the cognitive-emotional restructuring of astronauts suffering from space-related neuropsychiatric disease and injury, including mood, affect, and anxiety symptoms of any potential severity and pathophysiology. An appreciation of improved neuropsychiatric healthcare through the merging of new or rediscovered smart theragnostic medical technologies, capable of rendering personalized neuroplasticity training and managed psychotherapeutic treatment protocols, will reveal deeper insights into the illness states experienced by astronauts. Future work in this area should emphasize the ethical role of telemedicine and/or digital clinicians to advance the (semi)autonomous, technology-assisted medical prophylaxis, diagnosis, treatment, monitoring, and compliance of astronauts for elevated health, safety, and performance in remote extreme space and extraterrestrial environments.

Repetitive Transcranial Magnetic Stimulation Improves Brain-Derived Neurotrophic Factor and Cholinergic Signaling in the 3xTgAD Mouse Model of Alzheimer’s Disease

Background:

Alzheimer’s disease (AD) is a debilitating disorder involving the loss of plasticity and cholinergic neurons in the cortex. Pharmaceutical treatments are limited in their efficacy, but brain stimulation is emerging as a treatment for diseases of cognition. More research is needed to determine the biochemical mechanisms and treatment efficacy of this technique.

Objective:

We aimed to determine if forebrain repetitive transcranial magnetic stimulation can improve cortical BDNF gene expression and cholinergic signaling in the 3xTgAD mouse model of AD.

Methods:

Both B6 wild type mice and 3xTgAD mice aged 12 months were given daily treatment sessions for 14 days or twice weekly for 6 weeks. Following treatment, brain tissue was extracted for immunological stains for plaque load, as well as biochemical analysis for BDNF gene expression and cholinergic signaling via acetylcholinesterase and choline acetyltransferase ELISA assays.

Results:

For the 3xTgAD mice, both 14 days and 6 weeks treatment regimens resulted in an increase in BDNF gene expression relative to sham treatment, with a larger increase in the 6-week group. Acetylcholinesterase activity also increased for both treatments in 3xTgAD mice. The B6 mice only had an increase in BDNF gene expression for the 6-week group.

Conclusion:

Brain stimulation is a possible non-invasive and nonpharmaceutical treatment option for AD as it improves both plasticity markers and cholinergic signaling in an AD mouse model.

Optimal parameter determination of repetitive transcranial magnetic stimulation for treating treatment-resistant depression: A network meta-analysis of randomized controlled trials

BACKGROUND

Many studies have shown the efficacy of repetitive transcranial magnetic stimulation (rTMS) in treatment-resistant depression (TRD). However, the choice of different parameters has been a challenging issue.

METHODS

PubMed, Cochrane, and Embase databases were searched for relevant studies until June 20, 2022. The treatment efficacy was evaluated by the relative risk (RR) using the pairwise test for response and remission rates. Subgroup and sensitivity analyses were conducted to explore the primary outcome differences and to assess the reliability of the results.

RESULTS

Thirty-seven trials comprising 2120 participants with TRD were included. The more efficacious interventions compared to sham controls included high-frequency left followed by low-frequency right sup-threshold (HFL-LFR-sup-rTMS, RR = 5.29, 95% CI: 1.24-22.50), high-frequency left sup-threshold (HFL-sup-rTMS, RR = 2.97, 95% CI: 1.74-5.05), low-frequency right sup-threshold (LFR-sup-rTMS, RR = 2.72, 95% CI: 1.50-4.90), low-frequency right followed by high-frequency left sup-threshold (LFR-HFL-sup-rTMS, RR = 2.71, 95% CI: 1.62-4.53), and high-frequency left sub-threshold (HFL-sub-rTMS, RR = 1.91, 95% CI: 1.18-3.10) rTMS. The estimated relative ranking of treatments suggested that HFL-LFR-sup-rTMS (84.4%) might be the most efficacious among all rTMS strategies. No treatments showed a lower acceptability than the sham control.

LIMITATIONS

Subgroup analysis was not conducted to compare the efficacy of rTMS treatment between bipolar and unipolar depression, and small-study effects possibly introduced bias.

CONCLUSION

Treatment with HFL-LFR-sup-rTMS, HFL-sup-rTMS, LFR-sup-rTMS, LFR-HFL-sup-rTMS, or HFL-sub-rTMS is more efficacious than the sham control. HFL-LFR-sup-rTMS and HFL-sup-rTMS may be the two best among the most efficacious rTMS treatments.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/PROSPERO], identifier [CRD42022334481].

Improved object recognition memory using post-encoding repetitive transcranial magnetic stimulation

BACKGROUND

Brain stimulation is known to affect canonical pathways and proteins involved in memory. However, there are conflicting results on the ability of brain stimulation to improve to memory, which may be due to variations in timing of stimulation.

HYPOTHESIS

We hypothesized that repetitive transcranial magnetic stimulation (rTMS) given following a learning task and within the time period before retrieval could help improve memory.

METHODS

We implanted male B6129SF2/J mice (n = 32) with a cranial attachment to secure the rTMS coil so that the mice could be given consistent stimulation to the frontal area whilst freely moving. Mice then underwent the object recognition test sampling phase and given treatment +3, +24, +48 h following the test. Treatment consisted of 10 min 10 Hz rTMS stimulation (TMS, n = 10), sham treatment (SHAM, n = 11) or a control group which did not do the behavior test or receive rTMS (CONTROL n = 11). At +72 h mice were tested for their exploration of the novel vs familiar object.

RESULTS

At 72-h's, only the mice which received rTMS had greater exploration of the novel object than the familiar object. We further show that promoting synaptic GluR2 and maintaining synaptic connections in the perirhinal cortex and hippocampal CA1 are important for this effect. In addition, we found evidence that these changes were linked to CAMKII and CREB pathways in hippocampal neurons.

CONCLUSION

By linking the known biological effects of rTMS to memory pathways we provide evidence that rTMS is effective in improving memory when given during the consolidation and maintenance phases.

Repetitive Transcranial Magnetic Stimulation (rTMS) Modulates Thyroid Hormones Level and Cognition in the Recovery Stage of Stroke Patients with Cognitive Dysfunction

Background

This single-center study aimed to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on modulation of thyroid hormone levels and cognition in the recovery stage of patients with cognitive dysfunction following stroke.

Material/Methods

Seventy post-stroke patients who had cognitive impairment were randomly assigned to either the rTMS group or the control (sham) group. Both groups were administered basic treatment, with the rTMS group receiving rTMS (1 Hz, 90% MT, 1000 pulse/20 min, once a day for 5 days, for a total of 20 times), the stimulation site was the contralateral dorsolateral prefrontal cortex (DLPFC), and the sham group receiving sham stimulation which had the same stimulation parameters and site, except that the coil plane was placed perpendicular to the surface of the scalp. Cognitive function assessment and thyroid function tests were performed before and after 4 weeks of treatment.

Results

Serum levels of triiodothyronine (T3), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) showed a positive correlation with Montreal Cognitive Assessment (MoCA) scale score of stroke patients in the recovery phase. The post-treatment change in the scores of MoCA and Modified Barthel Index (MBI) and scores of 3 cognitive domains (visuospatial function, memory, and attention), as well as serum T3, FT3, and TSH levels, were improved more significantly in the rTMS group, and T3 and FT3 levels significantly affected the MoCA scores within the reference range.

Conclusions

Serum T3, FT3, and TSH levels of stroke patients in the recovery phase were positively correlated with MoCA score. rTMS increased T3, FT3, and TSH levels and also improved MoCA and MBI of patients in the recovery phase of stroke.

Effects of Noninvasive Brain Stimulation (NIBS) on Cognitive Impairment in Mild Cognitive Impairment and Alzheimer Disease: A Meta-analysis

OBJECTIVE

The purpose of this meta-analysis was to evaluate the beneficial effects and optimal stimulation protocol of noninvasive brain stimulation (NIBS) including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) on patients with mild cognitive impairment and Alzheimer disease.

MATERIALS AND METHODS

PubMed, Web of Science, Embase, and the Cochrane Library were searched until March 2020. The cognitive outcomes were extracted and the standardized mean difference with 95% confidence interval was calculated.

RESULTS

Twenty-eight studies were included. The result of NIBS showed significant effect on global cognition (P<0.05). Low-frequency rTMS over right dorsolateral prefrontal cortex (DLPFC), high-frequency rTMS (HF-rTMS) over left DLPFC, and the tDCS over left DLPFC and temporal lobe can significantly improve the memory function (P<0.05). HF-rTMS over left, right, or bilateral DLPFC can significantly improve the language function (P<0.05). Both HF-rTMS and tDCS over left DLPFC can obviously improve the executive function (P<0.05). Multiple sessions of rTMS with 80% to 100% intensity and anode tDCS with 2 mA current density are more suitable for all these functions.

CONCLUSIONS

NIBS has a beneficial effect on cognitive performance in both mild cognitive impairment and Alzheimer disease patients. Distinct optimal stimulation parameters were observed for different cognitive functions.

Transcranial Magnetic Stimulation as a Diagnostic and Therapeutic Tool in Various Types of Dementia

Dementia is recognized as a healthcare and social burden and remains challenging in terms of proper diagnosis and treatment. Transcranial magnetic stimulation (TMS) is a diagnostic and therapeutic tool in various neurological diseases that noninvasively investigates cortical excitability and connectivity and can induce brain plasticity. This article reviews findings on TMS in common dementia types as well as therapeutic results. Alzheimer’s disease (AD) is characterized by increased cortical excitability and reduced cortical inhibition, especially as mediated by cholinergic neurons and as documented by impairment of short latency inhibition (SAI). In vascular dementia, excitability is also increased. SAI may have various outcomes, which probably reflects its frequent overlap with AD. Dementia with Lewy bodies (DLB) is associated with SAI decrease. Motor cortical excitability is usually normal, reflecting the lack of corticospinal tract involvement. DLB and other dementia types are also characterized by impairment of short interval intracortical inhibition. In frontotemporal dementia, cortical excitability is increased, but SAI is normal. Repetitive transcranial magnetic stimulation has the potential to improve cognitive function. It has been extensively studied in AD, showing promising results after multisite stimulation. TMS with electroencephalography recording opens new possibilities for improving diagnostic accuracy; however, more studies are needed to support the existing data.

Repetitive transcranial magnetic stimulation increases the brain's drainage efficiency in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with high prevalence rate among the elderly population. A large number of clinical studies have suggested repetitive transcranial magnetic stimulation (rTMS) as a promising non-invasive treatment for patients with mild to moderate AD. However, the underlying cellular and molecular mechanisms remain largely uninvestigated. In the current study, we examined the effect of high frequency rTMS treatment on the cognitive functions and pathological changes in the brains of 4- to 5-month old 5xFAD mice, an early pathological stage with pronounced amyloidopathy and cognitive deficit. Our results showed that rTMS treatment effectively prevented the decline of long-term memories of the 5xFAD mice for novel objects and locations. Importantly, rTMS treatment significantly increased the drainage efficiency of brain clearance pathways, including the glymphatic system in brain parenchyma and the meningeal lymphatics, in the 5xFAD mouse model. Significant reduction of Aβ deposits, suppression of microglia and astrocyte activation, and prevention of decline of neuronal activity as indicated by the elevated c-FOS expression, were observed in the prefrontal cortex and hippocampus of the rTMS-treated 5xFAD mice. Collectively, these findings provide a novel mechanistic insight of rTMS in regulating brain drainage system and β-amyloid clearance in the 5xFAD mouse model, and suggest the potential use of the clearance rate of contrast tracer in cerebrospinal fluid as a prognostic biomarker for the effectiveness of rTMS treatment in AD patients.

Role of PKA/CREB/BDNF signaling in PM2.5-induced neurodevelopmental damage to the hippocampal neurons of rats

Exposure to fine particulate matter (PM2.5) is implicated in neurodevelopmental disorders including cognitive decline, attention-deficit/hyperactivity disorder, and autism spectrum disorder. However, the specific molecular mechanisms by which PM2.5 impacts neurodevelopment are poorly understood. Accordingly, in the present study, the role of protein kinase A (PKA)/cAMP response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling in PM2.5-induced neurodevelopmental damage was investigated using primary cultured hippocampal neurons. When hippocampal neurons cultured for 3 days in vitro (DIV3) were exposed to PM2.5 for 24 h and 96 h, neuronal viability decreased by 18.8% and 32.7% respectively, percentage of TUNEL-positive neurons increased by 78.5% and 64.0% separately, caspase-9 expression increased, lower postsynaptic density and shorter active zones were observed by transmission electron microscopy, expression of synapse-related proteins including postsynaptic density-95 (PSD95), growth associated protein-43 (GAP43), and synaptophysin (SYP) were decreased, and the phosphorylation levels of PKA, CREB, and BDNF expression also decreased. However, the PM2.5-induced neuronal damage could be ameliorated or aggravated to varying degrees by up- or down-regulation of the PKA/CREB/BDNF signaling pathway, respectively. Our results indicate that PM2.5 exposure exerts neurodevelopmental toxicity as indicated by lower viability, apoptosis, and synaptic damage in primary cultured hippocampal neurons, and that the PKA/CREB/BDNF pathways could play a vital role in PM2.5-mediated neurodevelopmental toxicity.

Effects of non-invasive brain stimulation in children and young people with psychiatric disorders: a protocol for a systematic review

BACKGROUND

Most psychiatric disorders have their onset in childhood or adolescence, and if not fully treated have the potential for causing life-long psycho-social and physical sequelae. Effective psychotherapeutic and medication treatments exist, but a significant proportion of children and young people do not make a full recovery. Thus, novel, safe, brain-based alternatives or adjuncts to conventional treatments are needed. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are non-invasive brain stimulation (NIBS) techniques which have shown clinical benefits in adult psychiatric conditions. However, in children and young people their efficacy is not well established. The objective of this study will be to systematically evaluate the evidence on clinical effects of NIBS in children and young people with psychiatric disorders, assessing disorder-specific symptoms, mood and neurocognitive functions.

METHODS

We designed and registered a study protocol for a systematic review. We will include randomised and non-randomised controlled trials and observational studies (e.g. cohort, case-control, case series) assessing the effects of NIBS in children and young people (aged ≤ 24 years old) for psychiatric disorders. The primary outcome will be reduction of disorder-specific symptoms. Secondary outcomes will include effects on mood and cognition. A comprehensive search from database inception onwards will be conducted in MEDLINE, EMBASE and PsycINFO. Grey literature will be identified through searching multiple clinical trial registries. Two reviewers will independently screen all citations, full-text articles and abstract data. The methodological quality of the studies will be appraised using appropriate tools. We will provide a narrative synthesis of the evidence and according to heterogeneity will conduct an appropriate meta-analysis. Additional analyses will be conducted to explore the potential sources of heterogeneity.

DISCUSSION

This systematic review will provide a broad and comprehensive evaluation of the evidence on clinical effects of NIBS in children and young people with psychiatric disorders. Our findings will be reported according to the PRISMA guidelines and will be of interest to multiple audiences (including patients, researchers, healthcare professionals and policy-makers). Results will be published in a peer-reviewed journal.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019158957.

Left lateral parietal rTMS improves cognition and modulates resting brain connectivity in patients with Alzheimer's disease: Possible role of BDNF and oxidative stress

Repetitive Transcranial Magnetic Stimulation (rTMS) is a non-invasive neuromodulation technique which is increasingly used for cognitive impairment in Alzheimer's Disease (AD). Although rTMS has been shown to modify Brain-Derived Neurotrophic Factor (BDNF) and oxidative stress levels in many neurological and psychiatric diseases, there is still no study evaluating the relationship between memory performance, BDNF, oxidative stress, and resting brain connectivity following rTMS in Alzheimer's patients. Furthermore, there are increasing clinical data showing that the stimulation of strategic brain regions may lead to more robust improvements in memory functions compared to conventional rTMS. In this study, we aimed to evaluate the possible disease-modifying effects of rTMS on the lateral parietal cortex in AD patients who have the highest connectivity with the hippocampus. To fill the mentioned research gaps, we have evaluated the relationships between resting-state Functional Magnetic Resonance Imaging (fMRI), cognitive scores, blood BDNF levels, and total oxidative/antioxidant status to explain the therapeutic and potential disease-modifying effects of rTMS which has been applied at 20 Hz frequencies for two weeks. Our results showed significantly increased visual recognition memory functions and clock drawing test scores which were associated with elevated peripheral BDNF levels, and decreased oxidant status after two weeks of left lateral parietal TMS stimulation. Clinically our findings suggest that the left parietal region targeted rTMS application leads to significant improvement in familiarity-based cognition associated with the network connections between the left parietal region and the hippocampus.

Safety and recommendations for TMS use in healthy subjects and patient populations, with updates on training, ethical and regulatory issues: Expert Guidelines

This article is based on a consensus conference, promoted and supported by the International Federation of Clinical Neurophysiology (IFCN), which took place in Siena (Italy) in October 2018. The meeting intended to update the ten-year-old safety guidelines for the application of transcranial magnetic stimulation (TMS) in research and clinical settings (Rossi et al., 2009). Therefore, only emerging and new issues are covered in detail, leaving still valid the 2009 recommendations regarding the description of conventional or patterned TMS protocols, the screening of subjects/patients, the need of neurophysiological monitoring for new protocols, the utilization of reference thresholds of stimulation, the managing of seizures and the list of minor side effects. New issues discussed in detail from the meeting up to April 2020 are safety issues of recently developed stimulation devices and pulse configurations; duties and responsibility of device makers; novel scenarios of TMS applications such as in the neuroimaging context or imaging-guided and robot-guided TMS; TMS interleaved with transcranial electrical stimulation; safety during paired associative stimulation interventions; and risks of using TMS to induce therapeutic seizures (magnetic seizure therapy). An update on the possible induction of seizures, theoretically the most serious risk of TMS, is provided. It has become apparent that such a risk is low, even in patients taking drugs acting on the central nervous system, at least with the use of traditional stimulation parameters and focal coils for which large data sets are available. Finally, new operational guidelines are provided for safety in planning future trials based on traditional and patterned TMS protocols, as well as a summary of the minimal training requirements for operators, and a note on ethics of neuroenhancement.

Individualized Responses to Ipsilesional High-Frequency and Contralesional Low-Frequency rTMS in Chronic Stroke: A Pilot Study to Support the Individualization of Neuromodulation for Rehabilitation

Background: In this pilot study, we examined the effects of ipsilesional high-frequency rTMS (iHF-rTMS) and contralesional low-frequency rTMS (cLF-rTMS) applied via a double-cone coil on neurophysiological and gait variables in patients with chronic stroke.

Objective/Hypothesis: To determine the group and individual level effects of two types of stimulation to better individualize neuromodulation for rehabilitation.

Methods: Using a randomized, within-subject, double-blind, sham-controlled trial with 14 chronic stroke participants iHF-rTMS and cLF-rTMS were applied via a double-cone coil to the tibialis anterior cortical representation. Neurophysiological and gait variables were compared pre-post rTMS.

Results: A small effect of cLF-rTMS indicated increased MEP amplitudes (Cohen’s D; cLF-rTMS, d = −0.30). Group-level analysis via RMANOVA showed no significant group effects of stimulation (P > 0.099). However, secondary analyses of individual data showed a high degree of response variability to rTMS. Individual percent changes in resting motor threshold and normalized MEP latency correlated with changes in gait propulsive forces and walking speed (iHF-rTMS, nLAT:Pp, R = 0.632 P = 0.015; cLF-rTMS, rMT:SSWS, R = −0.557, P = 0.039; rMT:Pp, R = 0.718, P = 0.004).

Conclusions: Changes in propulsive forces and walking speed were seen in some individuals that showed neurophysiological changes in response to rTMS. The neurological consequences of stroke are heterogeneous making a “one type fits all” approach to neuromodulation for rehabilitation unlikely. This pilot study suggests that an individual’s unique response to rTMS should be considered before the application/selection of neuromodulatory therapies. Before neuromodulatory therapies can be incorporated into standard clinical practice, additional work is needed to identify biomarkers of response and how best to prescribe neuromodulation for rehabilitation for post-stroke gait.

Effects of repetitive transcranial magnetic stimulation on depression symptoms and cognitive function in treating patients with postpartum depression: A systematic review and meta-analysis of randomized controlled trials

Repetitive transcranial magnetic stimulation (rTMS) has been used to treat postpartum depression (PPD), but its effectiveness is still uncertain. To evaluate the effect of rTMS on depression symptoms and recognition function in patients with PPD, we systematically searched CNKI, WanFang, VIP, EMbase, PubMed, CENTRAL, Web of Science, Physiotherapy Evidence Database from inception to June 2019 for randomized controlled trials (RCT) in English or Chinese concerning PPD in women treated with rTMS. Reference lists were also searched. RCT were included if they compared rTMS with no intervention or sham in patients with PPD. Related data was extracted and risk of bias was assessed by two investigators independently. Of 81 identified studies, 14 met our inclusion criteria (n=884 participants). Compared with control group, rTMS treatment yielded a reduction in Hamilton Depression Rating Scale score and Edinburgh Postnatal Depression Scale score, and improved the cognitive function of patients with PPD. Current evidence of RCT showed that rTMS could improve depression symptoms and cognitive function in patients with PPD.

Spinosin protects N2a cells from H2 O2 -induced neurotoxicity through inactivation of p38MAPK

OBJECTIVES

Previous studies have suggested that spinosin (SPI) exerted neuroprotective effects through inhibition of oxidative damage, but the underlying mechanisms are still unclear. Herein, the mechanisms underlying the protective effects of SPI against oxidative stress induced by hydrogen peroxide (H₂ O₂ ) were examined in neuro-2a (N2a) mouse neuroblastoma cells.

METHODS

N2a cells were pretreated with H₂ O₂ for 2 h, followed by a 24-h incubation with SPI. Intracellular reactive oxygen species (ROS) production was analysed by flow cytometry. Levels of Aβ_1-42 production were determined by ELISA assay. Levels of expression of c-Jun N-terminal kinase (JNK), p-JNK, extracellular signal-regulated kinase (ERK), p-ERK, p38 mitogen-activated protein kinase (p38MAPK), p-p38MAPK, p-Tau (Ser199), p-Tau (Ser202), p-Tau (Ser396), synaptophysin (SYP) and postsynaptic scaffold postsynaptic density-95 (PSD-95) were detected by Western blot analysis.

KEY FINDINGS

Our results showed that H₂ O₂ treatment enhanced intracellular ROS production in N2a cells. SPI prevented H₂ O₂ -induced oxidative damage via inhibiting Aβ_1-42 production, decreasing Tau phosphorylation and improving synaptic structural plasticity. Notably, H₂ O₂ -increased p38MAPK activation was attenuated by SPI administration, and p38MAPK inhibitor BIRB796 markedly reduced H₂ O₂ -induced oxidative damage in N2a cells.

CONCLUSIONS

Our findings suggest that SPI protects N2a cells from H₂ O₂ -induced oxidative damage through inactivation of p38MAPK.

A synergistic effect between family intervention and rTMS improves cognitive and negative symptoms in schizophrenia: A randomized controlled trial

OBJECTIVE

The present study explored an efficient new therapy that combined repetitive transcranial magnetic stimulation (rTMS) and family intervention in addition to risperidone to improve schizophrenia.

METHODS

A randomized controlled trial (January 2016-September 2017) involving 200 patients, of which 188 patients completed the 12-week study, and 50 controls were conducted in the research. The patients were randomly assigned to 12 weeks of treatment with risperidone alone (risperidone group), rTMS and risperidone (rTMS group), family intervention and risperidone (family intervention group), rTMS and risperidone plus family intervention (combined group). MATRICS Consensus Cognitive Battery (MCCB) and the Positive and Negative Symptoms Scale (PANSS) were used to evaluate treatment efficacy. Repeated measures analysis of variance (RMANOVA) were performed to evaluate different treatment efficacy between four groups after 12 weeks of treatment.

RESULTS

(1) There were no significant differences in sex, age, education, cognitive function, or PANSS scores between the four groups at baseline (p's > 0.05). (2) There was a significant decrease in the PANSS scores and an increase in the MCCB scores after 12 weeks of treatment in all groups (time effect p's < 0.001). (3) The improvements in positive symptoms and negative symptoms were more obvious in the combined group than in other groups (p's < 0.05). (4) The combined group showed the superior effect in cognition function after 12 weeks. (5) And, interestingly, a remarkable synergistic effect between rTMS and family intervention therapy was observed.

CONCLUSION

There was a synergistic effect between rTMS and the family intervention as an effective combined therapy in improving schizophrenia. This study is registered with Chictr.org, number ChiCTR1900024422 (http://www.chictr.org.cn/edit.aspx?pid=34285&htm=4).

Intermittent Theta Burst Stimulation Improves the Spatial Cognitive Function of Rats with Chronic Hypertension-induced Cerebral Small Vessel Disease

We investigated whether intermittent theta burst stimulation (iTBS) can improve the spatial cognitive function of rats with hypertension-induced cerebral small vessel disease. To prove our hypothesis, stroke-prone renovascular hypertensive rats (RHRSPs) were treated with iTBS beginning at postoperative week 22. The Morris water maze was performed to assess spatial cognitive function. The expression of the N-methyl-d-aspartate receptor (NMDAR) subunits NR1, NR2A and NR2B, calcium/calmodulin-dependent protein kinase IIα (CaMKIIα), p-CaMKIIα and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit 1 (GluR1) in the hippocampus were evaluated by western blot analysis. The distribution of GluR1, glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule-1 (IBa-1) in the CA1 and CA3 regions and dentate gyrus (DG) of the hippocampus were evaluated by immunofluorescence analysis. Treatment with iTBS significantly improved the spatial cognitive function of RHRSPs, increased the expression of NR2B, p-CaMKIIα and GluR1 in the hippocampus, and decreased the proliferation of astrocytes and microglia. Our results showed that iTBS treatment had a beneficial effect on the cognitive impairments induced by cerebral small vessel disease, potentially through the activation of the NR2B-CaMKII pathway, an increase in GluR1 expression and the suppression of astrocyte and microglial activation.

Preventive Electroacupuncture Ameliorates D-Galactose-Induced Alzheimer's Disease-Like Pathology and Memory Deficits Probably via Inhibition of GSK3β/mTOR Signaling Pathway

Acupuncture has been practiced to treat neuropsychiatric disorders for a thousand years in China. Prevention of disease by acupuncture and moxibustion treatment, guided by the theory of Chinese acupuncture, gradually draws growing attention nowadays and has been investigated in the role of the prevention and treatment of mental disorders such as AD. Despite its well-documented efficacy, its biological action remains greatly invalidated. Here, we sought to observe whether preventive electroacupuncture during the aging process could alleviate learning and memory deficits in D-galactose-induced aged rats. We found that preventive electroacupuncture at GV20-BL23 acupoints during aging attenuated the hippocampal loss of dendritic spines, ameliorated neuronal microtubule injuries, and increased the expressions of postsynaptic PSD95 and presynaptic SYN, two important synapse-associated proteins involved in synaptic plasticity. Furthermore, we observed an inhibition of GSK3β/mTOR pathway activity accompanied by a decrease in tau phosphorylation level and prompted autophagy activity induced by preventive electroacupuncture. Our results suggested that preventive electroacupuncture can prevent and alleviate memory deficits and ameliorate synapse and neuronal microtubule damage in aging rats, which was probably via the inhibition of GSK3β/mTOR signaling pathway. It may provide new insights for the identification of prevention strategies of AD.

The experimental research on neuroplasticity in rats' hippocampus subjected to chronic cerebral hypoperfusion and interfered by Modified Dioscorea Pills

Background

Chronic Cerebral Hypoperfusion (CCH) is a common, crucial and tough problem for old people. It easily leads to Lacunar Infarction and even Vascular Dementia (VD). Western medicine has the advantage to relieve some VD symptoms but fails to cure it. Some classic Chinese medicines have good efficacies to treat and delay the cerebral functional decline resulted from CCH. Among them Modified Dioscorea Pills (MDP) has been proven to have a convincing effect in curing VD. So far the knowledge about neuroplasticity in CCH is little known and the underlying interfered mechanism by MDP on neuroplasticity has not yet been explored. This study explores the changes of neuroplasticity involving neurogenesis, angiogenesis and synaptogenesis in CCH and interfered by MDP.

Methods

40 male SD rats were divided into the Sham operated Group, the Model Group and the MDP Group according to a Random Number Table. Bilateral Common Carotid Arteries Occlusion (BCCAO) was adopted to prepare CCH models. MDP condense decoction had been administered by gavage to rats in the MDP Group (10g·Kg-1·d-1) for 45 days; Rats in the other two groups were accepted normal salts as substitution with same dosage and course. Through Morris Water Maze (MWM) test, pathological observation of hippocampus, ultrastructural study on synapse, Real Time Polymerase Chain Reaction (RT-PCR) and immunohistochemistry detection, the capacities of intelligence of rats, the morphological character of hippocampus CA1 zone and the synapse associated protein and gene such as Growth Associated Protein (GAP-43) mRNA, Vascular Endothelial Growth Factor (VEGF) mRNA, Microtubule-associated Protein (MAP)-2, Synaptophysin (SYP), Postsynaptic Density protein (PSD)-95 and Micro Vessel Density (MVD) were determined. Through one-way ANOVA the data was analyzed and when P＜0.05 the result was considered significant.

Results

Compared to the Model Group, rats in the MDP Group achieved much better behavioral performance (P＜0.05); more neurons and more synapses regenerated; the expression of SYP, PSD-95and MAP-2 up-regulated (P＜0.05); The expressions of GAP-43 mRNA and VEGF mRNA in the Model Group were higher than those in the Sham operated Group (P＜0.05), but they reached the highest in the MDP Group (P＜0.05); The count of MVD in the Sham operated Group is the lowest, it is higher in the MDP Group and it reaches highest in the Model Group (P＜0.05).

Conclusions

Some key genes promoting neuroplasticity such as GAP-43 mRNA and VEGF mRNA remarkably up-regulated in CCH, they only boost angiogenesis but fail to facilitate neurogenesis and synaptogenesis in CCH. However, accompanied by furtherly up-regulation of these two key genes, MDP obviously improves neurogenesis, synaptogenesis and temperate angiogenesis in CCH which may be underlying its good efficacy.

Effects of early postnatal exposure to fine particulate matter on emotional and cognitive development and structural synaptic plasticity in immature and mature rats

INTRODUCTION

Fine particulate matter (PM2.5) is closely associated with many neurological disorders including neurodegenerative disease, stroke, and brain tumors. However, the toxic effects of PM2.5 on neurodevelopment remain unclear. In this study, we aimed to determine the neurotoxic effects of early postnatal exposure to PM2.5 in immature and mature rats.

METHODS

We exposed neonatal rats to PM2.5 (2 or 10 mg/kg body weight) through intranasal instillation from postnatal day (PND) 3-15, once a day. Emotional and cognitive development were evaluated using the elevated plus maze, forced swimming, and Morris water maze tests. Hippocampal tissue was collected and subjected to transmission electron microscopy observation and western blot analysis.

RESULTS

Rats had lower body weight after exposure to high dose of PM2.5. The behavioral test results indicated that high-dose PM2.5 exposure led to increased anxiety-like symptoms in immature and mature rats, apparent depressive-like behaviors in mature rats, and impaired spatial learning and memory abilities in immature rats, and low-dose PM2.5 exposure increased anxiety-like behaviors in immature rats. Further, high-dose PM2.5 exposure contributed to fewer synapses, thinner postsynaptic density, and shorter active zone in immature and mature rats, and also decreased expressions of synaptophysin (SYP), growth associated protein-43 (GAP43), and postsynaptic density-95 (PSD95) in immature rats, SYP and PSD95 in mature rats. Moreover, low-dose PM2.5 exposure diminished the expression of PSD95 in immature rats. In addition, high-dose PM2.5 exposure reduced brain-derived neurotrophic factor (BDNF) expression and cAMP response element binding protein (CREB) phosphorylation in both immature and mature rats, and low-dose PM2.5 exposure lessened BDNF expression and CREB phosphorylation in immature rats.

CONCLUSIONS

Our findings indicate that PM2.5 impairs emotional and cognitive development by disrupting structural synaptic plasticity, possibly via the CREB/BDNF signaling pathway.

High Frequency Repetitive Transcranial Magnetic Stimulation Alleviates Cognitive Impairment and Modulates Hippocampal Synaptic Structural Plasticity in Aged Mice

Normal aging is accompanied by hippocampus-dependent cognitive impairment, which is a risk factor of Alzheimer’s disease. This study aims to investigate the effect of high frequency-repetitive transcranial magnetic stimulation (HF-rTMS) on hippocampus-dependent learning and memory in aged mice and explore its underlying mechanisms. Forty-five male Kunming mice (15 months old) were randomly divided into three groups: aged sham, 5 Hz rTMS, and 25 Hz rTMS. Two sessions of 5 Hz or 25 Hz rTMS comprising 1,000 pulses in 10 trains were delivered once a day for 14 consecutive days. The aged sham group was treated by the reverse side of the coil. In the adult sham group, 15 male Kunming mice (3 months old) were treated the same way as the aged sham group. A Morris water maze (MWM) was conducted following the stimulation, and synaptic ultrastructure was observed through a transmission electron microscope. HF-rTMS improved spatial learning and memory impairment in the aged mice, and 5 Hz was more significant than 25 Hz. Synaptic plasticity-associated gene profiles were modified by HF-rTMS, especially neurotrophin signaling pathways and cyclic adenosine monophosphate response element binding protein (CREB) cofactors. Compared to the aged sham group, synaptic plasticity-associated proteins, i.e., synaptophysin (SYN) and postsynaptic density (PSD)-95 were increased; brain-derived neurotrophic factor (BDNF) and phosphorylated CREB (pCREB) significantly increased after the 5 Hz HF-rTMS treatment. Collectively, our results suggest that HF-rTMS ameliorated cognitive deficits in naturally aged mice. The 5 Hz rTMS treatment significantly enhanced synaptic structural plasticity and activated the BDNF/CREB pathway in the hippocampus.