Noninvasive human brain stimulation

Causal Contributions of the SMA to Alertness and Consciousness Interactions

Phasic alertness facilitates conscious perception through a fronto-striatal network, including the supplementary motor area (SMA). The functioning of the ventral attentional network has been related to the alerting system, overlapping with the ventral branch of the superior longitudinal fasciculus (SLF III). In this study, we use repetitive transcranial magnetic stimulation (rTMS) and a conscious detection task with near-threshold stimuli that could be preceded by an alerting tone to explore the causal implication of the SMA in the relationship between phasic alertness and conscious perception. Complementary to SMA stimulation, a sham and an active condition (left inferior parietal lobe; IPL) were included. Deterministic tractography was used to isolate the right and left SLF III. Behaviorally, the alerting tone enhanced conscious perception and confidence ratings. rTMS over the SMA reduced the alerting effect on the percentage of perceived stimuli while rTMS over the left IPL produced no modulations, demonstrating a region-specific effect. Additionally, a correlation between the rTMS effect and the integrity of the right SLF III was found. Our results highlight the causal implication of a frontal region, the SMA, in the relationship between phasic alertness and conscious perception, which is related to the white matter microstructure of the SLF III.

Transcranial Magnetic Stimulation-Induced Motor Evoked Potentials in Hirayama Disease: Systematic Review of the Literature

PURPOSE

Hirayama disease (HD) is a rare motor disorder mainly affecting young men, characterized by atrophy and unilateral weakness of forearm and hand muscles corresponding to a C7-T1 myotome distribution. The progression is self-limited. The etiology of HD is unclear. The usefulness of motor evoked potentials (MEPs) in pyramidal tracts damage evaluation still appears to be somehow equivocal.

METHODS

We searched PubMed for original articles, evaluating the use of transcranial magnetic stimulation elicited MEPs in HD using keywords "motor evoked potentials Hirayama" and "transcranial magnetic stimulation Hirayama."

RESULTS

We found seven articles using the above keywords that met inclusion criteria. The number of participants was small, and diagnostic procedures varied. There were also differences in methodology. Abnormal central motor conduction time was found in 17.1% of patients in one study, whereas it was normal in two other studies. Peripheral motor latency was evaluated in one study, which found abnormally increased peripheral motor latencies in at least one tested muscle in 16 of 41 HD patients (39.0%). Abnormal MEP parameters were found in three studies in 14.3% to 100% patients. In one study they were not evaluated, in three other studies they were normal, and in one they were normal also in standard and flexed neck position In one study, inconsistent results were found in MEP size after neck flexion in patients after treatment with neck collar.

CONCLUSIONS

Although MEP parameters may be abnormal in some HD patients, these have not been thoroughly assessed. Further studies are indispensable to evaluate their usefulness in assessing pyramidal tract damage in HD.

Memory and Cognition-Related Neuroplasticity Enhancement by Transcranial Direct Current Stimulation in Rodents: A Systematic Review

Brain stimulation techniques, including transcranial direct current stimulation (tDCS), were identified as promising therapeutic tools to modulate synaptic plasticity abnormalities and minimize memory and learning deficits in many neuropsychiatric diseases. Here, we revised the effect of tDCS on the modulation of neuroplasticity and cognition in several animal disease models of brain diseases affecting plasticity and cognition. Studies included in this review were searched following the terms (“transcranial direct current stimulation”) AND (mice OR mouse OR animal) and according to the PRISMA statement requirements. Overall, the studies collected suggest that tDCS was able to modulate brain plasticity due to synaptic modifications within the stimulated area. Changes in plasticity-related mechanisms were achieved through induction of long-term potentiation (LTP) and upregulation of neuroplasticity-related proteins, such as c-fos, brain-derived neurotrophic factor (BDNF), or N-methyl-D-aspartate receptors (NMDARs). Taken into account all revised studies, tDCS is a safe, easy, and noninvasive brain stimulation technique, therapeutically reliable, and with promising potential to promote cognitive enhancement and neuroplasticity. Since the use of tDCS has increased as a novel therapeutic approach in humans, animal studies are important to better understand its mechanisms as well as to help improve the stimulation protocols and their potential role in different neuropathologies.

Cathodal tDCS Guided by Thermography as Adjunctive Therapy in Chronic Migraine Patients: A Sham-Controlled Pilot Study

Objective: To explore the efficacy of cathodal tDCS applied ipsilateral to the cold patch, as determined by thermographic evaluation, in the treatment of chronic migraine. Background: Transcranial direct current stimulation (tDCS) is a non-invasive and safe technique that modulates the activity of the underlying cerebral cortex. tDCS has been extensively tested as a possible treatment for chronic pain and migraine with controversial results mainly due to the different setting procedure and location of electrodes. Since the presence of a hypothermic patch region detected through thermography has been suggested as a possible support for headache diagnosis, this "cold patch" could considered as possible effective location for tDCS application. Methods: Forty-five patients with chronic migraine were randomized to receive either cathodal (25 patients) or sham tDCS, for 5 consecutive daily sessions plus a recall session after 1 month. Cathodal tDCS was delivered at 1.5 mA for 15 min in each session. Subjects were evaluated before treatment (baseline, T0), and after 10 (T10), 60 (T60), and 120 (T120) days after treatment. The number of attacks, duration of attacks, pain intensity, number of days with headache, and number of analgesics were collected at each time evaluation. Results: Patients in the tDCS group showed a significant improvement compared to the sham group, during the whole study period in the frequency of migraine attacks (tDCS vs. sham: -47.8 ± 50.1% vs. -14.2 ± 16.5%, p = 0.004), number of days with headache (tDCS vs. sham: -42.7 ± 65.4% vs. -11.3 ± 18.0%, p = 0.015), duration of attacks (tDCS vs. sham: -29.1 ± 43.4% vs. -7.5 ± 17.6%, p = 0.016), intensity of the pain during an attack (tDCS vs. sham -31.1 ± 36.9% vs. 8.3 ± 13.5%, p = 0.004), and number of analgesics (tDCS vs. sham -54.3 ± 37.4% vs. -16.0 ± 19.6%, p < 0.0001). Conclusion: Our results suggest that cathodal tDCS is an effective adjuvant technique in migraine provided that an individual correct montage of the electrodes is applied, according to thermographic investigation.

Augmenting the unified protocol for transdiagnostic treatment of emotional disorders with transcranial direct current stimulation in individuals with generalized anxiety disorder and comorbid depression: A randomized controlled trial

BACKGROUND

The aim of the current study was to compare the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP) with and without transcranial direct current stimulation (tDCS) in individuals suffering from generalized anxiety disorder (GAD) and comorbid depression.

METHODS

A total of 43 individuals diagnosed with GAD and comorbid depression enrolled in a randomized controlled trial (IRCT20140929019334N1). Participants were randomly assigned to three groups including UP with tDCS (UP+tDCS; n = 15), UP alone (UP; n = 13) or wait-list control (n = 15). GAD and depression symptoms, worry severity, anxiety sensitivity, and intolerance of uncertainty were assessed at baseline, post-treatment and 3-month follow-up.

RESULTS

Treatment with both UP+tDCS and UP alone resulted in significant lower ratings across all measures relative to wait-list controls at post-treatment and 3-month follow-up (all p-values <0.001). UP+tDCS showed significantly greater reductions in anxiety (p = 0.001 post-treatment; p = 0.003 follow-up), worry (p = 0.001 post-treatment; p = 0.002 follow-up), and anxiety sensitivity (p = 0.003 post-treatment; p = 0.002 follow-up) relative to UP alone.

LIMITATIONS

The present study had some limitations. First, the sample size was low. Another limitation was the use of a short-term follow-up.

CONCLUSIONS

These results suggest augmenting UP treatment with tDCS may be an efficacious strategy to improve treatment outcomes in GAD with comorbid depression. Trial registration reference is IRCT20140929019334N1 (see https://irct.ir/trial/27988).

Neural and Psychological Predictors of Cognitive Enhancement and Impairment from Neurostimulation

Modulating the temporoparietal junction (TPJ), especially the right counterpart, shows promises in enhancing social cognitive ability. However, it is ambiguous whether the functional lateralization of TPJ determines people's responsiveness to brain stimulation. Here, this issue is investigated with an individual difference approach. Forty-five participants attended three sessions of transcranial direct current stimulation (tDCS) experiments and one neuroimaging session. The results support the symmetric mechanism of left and right TPJ stimulation. First, the left and right TPJ stimulation effect are comparable in the group-level analysis. Second, the individual-level analysis reveals that a less right-lateralized TPJ is associated with a higher level of responsiveness. Participants could be classified into positive responders showing cognitive enhancement and negative responders showing cognitive impairment due to stimulation. The positive responders show weaker connectivity between bilateral TPJ and the medial prefrontal cortex, which mediates the prediction of offline responsiveness by the lateralization and the social-related trait. These findings call for a better characterization and predictive models for whom tDCS should be used for, and highlight the necessity and feasibility of prestimulation screening.

Ultra-focal Magnetic Stimulation Using a µTMS coil: a Computational Study

A new miniaturized figure-of-eight coil (μCoil) for TMS applications has been developed taking advantage of the Flex circuit technology. First experiments on volunteers demonstrated the ability of the μCoil to elicit sensorial action potentials of the peripheral nervous system. The necessity of reducing the size of standard TMS stimulator arises from the poor spatial resolution of the latter. This study aims to model the μCoil and study the electromagnetic fields induced inside the arm during peripheral nerve stimulation. Results confirmed that the μCoil is capable of inducing a focalized electric field inside the tissues with amplitudes up to 70V/m consistent with the observed peripheral nerve stimulation in healthy volunteers.

Skull Impact on the Ultrasound Beam Profile of Transcranial Focused Ultrasound Stimulation

Transcranial focused ultrasound stimulation (tFUS) is a promising noninvasive neuromodulation tool for targeting brain regions with millimeter-scale spatial resolutions. In conventional tFUS studies, a focused ultrasound beam generated by an external ultrasound transducer is delivered to the neural target. In tFUS, ultrasound should travel through the skull that features large attenuation and different acoustic impedance compared with the soft tissue, thereby resulting in acoustic impedance mismatch and reflections. In this paper, we study the impact of the rat skull on the ultrasound beam profile generated by both focused and unfocused (but with a natural focus) transducers at a wide sonication frequency (f_p) range of 0.5-9.5 MHz. At different axial and lateral distances from the transducers, we measured ultrasound intensity profiles of three transducers operating at f_ps of 0.5 MHz, 1.2 MHz and 9.5 MHz with and without the skull. Our results showed that ultrasound beam profiles were significantly distorted by the skull. The transmission factor due to skull attenuation was measured 0.79,0.34 and 0.03 at f_ps of 0.5 MHz, 1.2 MHz and 9.5 MHz, respectively, when the skull was close to transducers focal zones.

Effects of a combined transcranial magnetic stimulation (TMS) and cognitive training intervention in patients with Alzheimer's disease

INTRODUCTION

This clinical trial evaluates the efficacy and safety of a 6-week course of daily neuroAD™ therapy.

METHODS

131 subjects between 60 and 90 years old, unmedicated for Alzheimer's disease (AD), or on stable doses of an acetylcholinesterase inhibitor and/or memantine, with Mini-Mental State Examination scores between 18 and 26, clinical dementia rating scale scores of 1 or 2, enrolled for a prospective, randomized, double-blind, sham-controlled, multicenter clinical trial. Structural brain MRIs were obtained for transcranial magnetic stimulation targeting. Baseline Alzheimer's disease assessment scale-cognitive (ADAS-Cog) and Clinical Global Impression of Change were assessed. 129 participants were randomized to active treatment plus standard of care (SOC) or sham treatments plus SOC.

RESULTS

Subjects with baseline ADAS-Cog ≤ 30 (~85% of study population) showed a statistically significant benefit favoring active over sham. Responder analysis showed 31.7% participants in the active group with ≤ -4 point improvement on ADAS-Cog versus 15.4% in the sham group.

DISCUSSION

neuroAD™ Therapy System provides a low-risk therapeutic benefit for patients with milder AD (baseline ADAS-Cog ≤30) beyond pharmacologic SOC.

Brain Stimulation in Obsessive-Compulsive Disorder (OCD): A Systematic Review

Background

Obsessive-compulsive disorder (OCD) is a highly prevalent, severe, and chronic disease. There is a need for alternative strategies for treatment-resistant OCD.

Objective

This review aims to assess the effect of brain stimulation techniques in OCD.

Method

We included papers published in peer-reviewed journals dealing with brain stimulation techniques in OCD. We conducted treatment-specific searches for OCD (Technique AND ((randomized OR randomised) AND control* AND trial) AND (magnetic AND stimulation OR (rTMS OR dTMS)) AND (obsess* OR compuls* OR OCD)) on six databases, i.e., PubMed, Cochrane, Scopus, CINAHL, PsycINFO, and Web of Science to identify randomised controlled trials and ClinicalTrials.gov for possible additional results.

Results

Different add-on stimulation techniques could be effective for severely ill OCD patients unresponsive to drugs and/or behavioural therapy. Most evidence regarded deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS), while there is less evidence regarding transcranial direct current stimulation (tDCS), electroconvulsive therapy, and vagus nerve stimulation (for these last two there are no sham-controlled studies). Low-frequency TMS may be more effective over the supplementary motor area or the orbitofrontal cortex. DBS showed best results when targeting the crossroad between the nucleus accumbens and the ventral capsule or the subthalamic nucleus. Cathodal tDCS may be better than anodal in treating OCD. Limitations. We had to include methodologically inconsistent underpowered studies.

Conclusion

Different brain stimulation techniques are promising as an add-on treatment of refractory OCD, although studies frequently reported inconsistent results. TMS, DBS, and tDCS could possibly find some use with adequate testing, but their standard methodology still needs to be established.

Enhancing the effects of transcranial magnetic stimulation with intravenously injected magnetic nanoparticles

Transcranial magnetic stimulation (TMS) is a non-invasive and clinically approved method for treating neurological disorders. However, the relatively weak intracranial electric current induced by TMS is an obvious inferiority which can only produce limited treatment effects in clinical application. The present study aimed to investigate the possibility of enhancing the effects of TMS with intravenously administrated magnetic nanoparticles. To facilitate crossing of the blood-brain barrier (BBB), the superparamagnetic iron oxide nanoparticles (SPIONs) were coated with carboxylated chitosan and poly(ethylene glycol). To aid the nanoparticles in crossing the BBB and targeting the predesigned brain regions, an external permanent magnet was attached to the foreheads of the rats before the intravenous administration of SPIONs. The electrophysiological tests showed that the maximum MEP amplitude recorded in an individual rat was significantly higher in the SPIONs + magnet group than in the saline group (5.78 ± 2.54 vs. 1.80 ± 1.55 mV, P = 0.015). In the M1 region, biochemical tests detected that the number density of c-fos positive cells in the SPIONs + magnet group was 3.44 fold that of the saline group. These results suggest that intravenously injected SPIONs can enhance the effects of TMS in treating neurological disorders.

TRANSCRANIAL DIRECT-CURRENT STIMULATION IN COMBINATION WITH EXERCISE: A SYSTEMATIC REVIEW

ABSTRACT Introduction Transcranial direct-current stimulation (tDCS) is a noninvasive technique that allows the modulation of cortical excitability and can produce changes in neuronal plasticity. The application of tDCS has recently been associated with physical activity. Objectives To verify the effect of Transcranial Direct-Current Stimulation (tDCS) in combination with physical exercise, characterizing methodological aspects of the technique. Methods In the database search, studies with animals, other neuromodulation techniques and opinion and review articles were excluded. Publications up to 2016 were selected and the methodological quality of the articles was verified through the PEDro scale. Results The majority of studies (86%) used tDCS on the motor cortex area, with anodal current and the allocation of monocephalic electrodes (46.5%). The prevalent current intensity was 2mA (72%), with duration of 20min (55.8%). The profile of the research participants was predominantly of subjects aged up to 60 years (72.1%). The outcomes were favorable for the use of anodal tDCS in combination with physical exercise. Conclusion Transcranial Direct-Current Stimulation is a promising technique when used in combination with aerobic and anaerobic exercises; however, it is necessary to investigate concurrent exercise. Level of Evidence II; Therapeutic Studies Investigating the Results of Treatment (systematic review of Level II studies or Level I studies with inconsistent results).

Development of Multi-Layer Lateral-Mode Ultrasound Needle Transducer for Brain Stimulation in Mice

Ultrasound, a non-invasive stimulation method, has proved effective in neurostimulation. Previous studies have demonstrated that low-frequency ultrasound (less than 1 MHz) is preferable owing to better penetrability through tissue and skull. However, the large size of low-frequency transducers, which are used in ultrasound neurostimulation studies, makes it difficult to perform multiple-target neurostimulation, especially in small animals such as mice. In this paper, a proposed low-frequency ultrasound needle transducer based on the multi-layer lateral-mode coupling method with a miniature aperture of 0.6 mm × 0.6 mm and a thickness of 1.65 mm was designed and fabricated. The measured electrical impedance of the fabricated 8-layer lateral-mode PZT-5H ceramic was 50.76 Ω at a resonant frequency of 866 kHz. The -6 dB bandwidth of 8-layer lateral-mode transducer was 29% at a center frequency of 876 kHz. The maximum ultrasound peak pressure amplitude at 820 kHz reached approximately 300 kPa, 4-5 times higher than that of the single-layer thickness-mode transducer with 200 V input voltage. The ultrasound beam showed no attenuation and low shift through mouse skull. To verify the feasibility of using the needle transducer to perform multiple-target nerve stimulation in mice brains, we constructed an ultrasound stimulus system to simultaneously stimulate two areas (M2 and V1) of the mouse brain in vivo and detected the c-Fos expression by immunofluorescence to evaluate the effect of stimulation. The results showed that a high ultrasound peak pressure amplitude with this transducer configuration is useful for ultrasound neurostimulation and multiple-target stimulation in mice.

Effects of repetitive transcranial magnetic stimulation on nicotine consumption and craving: A systematic review

We performed a systematic review of the studies employing repetitive transcranial magnetic stimulation (rTMS) in subjects with smoking addiction. High-frequency (HF) rTMS over the prefrontal cortex (PFC), in particular the left dorsolateral PFC (DLPFC), might represent a save and innovative treatment tool for tobacco consumption and craving in nicotine-dependent otherwise healthy people. rTMS can be effective for this indication also in patients with schizophrenia, but the results are conflicting and sufficient evidence from large-scale trials is still lacking. Promising results have been obtained using particular techniques for brain stimulation, such as deep rTMS and theta burst stimulation. Multiple-target HF rTMS can also have a potential in smoking cessation. fMRI and EEG recordings have proven to be useful for objectively assessing the treatment effects. TMS is likely to be most effective when paired with an evidence-based self-help intervention, cognitive-behavioral interventions and nicotine replacement therapy. However, the most recent studies employed different protocols and yielded heterogeneous results, which should be replicated in further controlled studies with larger sample sizes and rigorous standards of randomization. To date, no recommendation other than that a possible efficacy of HF-rTMS of the left DLPFC can be made for alternative rTMS procedures in nicotine craving and consumption.

New Directions in the Use of Brain Stimulation Interventions in Patients with Obsessive-Compulsive Disorder

Obsessive-Compulsive Disorder (OCD) is a highly disabling condition with early onset and chronic course in most of the affected patients. In addition, OCD may show high comorbidity and suicide attempt rates, which worsen the overall burden of the disease for patients and their caregivers. First-line treatments for OCD consist of pro-serotonergic compounds and cognitive-behavioral therapy. Nonetheless, many patients show only limited benefit from such interventions and require additional "next-step" interventions, including augmentative antipsychotics and glutamate-modulating agents. Based on the knowledge about altered neurocircuitry in OCD, brain stimulation techniques, including transcranial magnetic and electrical stimulations (TMS and tDCS) and deep brain stimulation (DBS), have been increasingly investigated over the last decade, revealing positive results for otherwise intractable and treatment-refractory patients. Available evidence in the field is in continuous evolution and professionals actively involved in the management of OCD patients, psychiatrists in particular, need to be updated about latest developments. Through the analysis of controlled studies, meta-analyses, and International treatment guidelines, the present article is aimed at providing the state of the art on the use of brain stimulation techniques for the treatment of OCD.

A Comprehensive Study of Ultrasound Transducer Characteristics in Microscopic Ultrasound Neuromodulation

In order to improve the spatial resolution of transcranial focused ultrasound stimulation (tFUS), we have recently proposed microscopic ultrasound stimulation (μUS). In μUS, either an electronically phased array of ultrasound transducers or several millimeter-sized focused transducers are placed on the brain surface or sub-millimeter-sized transducers are implanted inside the brain tissue to steer and deliver a focused ultrasound pressure directly to the neural target. A key element in both tFUS and μUS is the ultrasound transducer that converts electrical power to acoustic pressure. The literature lacks a comprehensive study (in a quantitative manner) of the transducer characteristics, such as dimension, focusing, acoustic matching, backing material, and sonication frequency (fp), in the μUS. This paper studies the impact of these design parameters on the acoustic beam profile of millimeter-sized transducers with the emphasis on the stimulation spatial resolution and energy efficiency, which is defined as the μUS figure-of-merit (FoM). For this purpose, disc-shaped focused and unfocused piezoelectric (PZT-5A) transducers with different dimension (diameter, thickness), backing material (PCB, air) and acoustic matching in the frequency range of 2.2-9.56 MHz were fabricated. Our experimental studies with both water and sheep brain phantom medium demonstrate that acoustically matched focused transducers with high quality factor are desirable for μUS, as they provide fine spatial resolution and high acoustic intensities with low input electrical power levels (i.e., high FoM).

Functional Balance and Postural Control Improvements in Patients With Stroke After Noninvasive Brain Stimulation: A Meta-analysis

OBJECTIVES

The postural imbalance poststroke limits individuals' walking abilities as well as increase the risk of falling. We investigated the short-term treatment effects of noninvasive brain stimulation (NIBS) on functional balance and postural control in patients with stroke.

DATA SOURCES

We started the search via PubMed and the Institute for Scientific Information's Web of Science on March 1, 2019 and concluded the search on April 30, 2019.

STUDY SELECTION

The meta-analysis included studies that used either repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) for the recovery of functional balance and postural control poststroke. All included studies used either randomized controlled trial or crossover designs with a sham control group.

DATA EXTRACTION

Three researchers independently performed data extraction and assessing methodological quality and publication bias. We calculated overall and individual effect sizes using random effects meta-analysis models.

DATA SYNTHESIS

The random effects meta-analysis model on the 18 qualified studies identified the significant positive effects relating to NIBS in terms of functional balance and postural control poststroke. The moderator-variable analyses revealed that these treatment effects were only significant in rTMS across patients with acute, subacute, and chronic stroke whereas tDCS did not show any significant therapeutic effects. The meta-regression analysis showed that a higher number of rTMS sessions was significantly associated with more improvements in functional balance and postural control poststroke.

CONCLUSIONS

Our systematic review and meta-analysis confirmed that NIBS may be an effective option for restoring functional balance and postural control for patients with stroke.

Effects of High Frequency Repetitive Transcranial Magnetic Stimulation (HF-rTMS) on Delay Discounting in Major Depressive Disorder: An Open-Label Uncontrolled Pilot Study

BACKGROUND

Delay discounting (DD) refers to the decrease of a present subjective value of a future reward as the delay of its delivery increases. Major depressive disorder (MDD), besides core emotional and physical symptoms, involves difficulties in reward processing. Depressed patients often display greater temporal discounting rates than healthy subjects. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique applied in several countries to adult patients with treatment resistant depression. Studies suggest that this technique can be used to modulate DD, but no trial has assessed its effects on depressed patients.

METHODS

In this open-label uncontrolled trial, 20 patients diagnosed with MDD and at least stage II treatment resistance criteria underwent 20 HF-rTMS sessions over the dorsolateral prefrontal cortex (dlPFC; 10 Hz, 110% MT, 20 min). Pre-post treatment DD rates were compared. Effects on impulsivity, personality factors, and depressive symptoms were also evaluated.

RESULTS

No significant effect of HF-rTMS over the left dlPFC on DD of depressed individuals was observed, although rates seemed to increase after sessions. However, treatment resulted in significant improvement on cognitive impulsivity and depressive symptoms, and was well-tolerated.

CONCLUSION

Despite the limitations involved, this pilot study allows preliminary evaluation of HF-rTMS effects on DD in MDD, providing substrate for further research.

Repetitive Transcranial Magnetic Stimulation Improves Depressive Symptoms and Quality of Life of Poststroke Patients-Prospective Case Series Study

Background:

Poststroke depression (PSD) is a serious psychiatric complication often reported after a stroke. Nearly a third of stroke survivors experience depressive symptoms at some point, affecting their functional recovery and quality of life. In recent years, repetitive transcranial magnetic stimulation (rTMS) has been studied by many researchers and found to be a safe supporting tool for the treatment of PSD.

Objective:

We aim to evaluate the effects of rTMS on PSD and on the quality of life of poststroke patients.

Method:

A prospective clinical case series, performed at CRER Rehabilitation, Brazil, between June 2016 and May 2017. A nonprobabilistic sample (n = 15) was divided into 2 groups (excitatory stimulation in F3, n = 8; inhibitory stimulation in F4, n = 7) and underwent 20 sessions of rTMS. Individuals were assessed according to the 17-item Hamilton Depression Rating Scale (HAM-D17) and World Health Organization Quality of Life-Brief Version (WHOQOL-BREF) questionnaire at 3 different moments: baseline, at the end of the treatment, and in a 1-month follow-up meeting.

Results:

Both groups presented a significant change in the score of all WHOQOL-BREF domains and in HAM-D17. In the group that received inhibitory stimulation (F4), score changes were continuous and gradual, comparing the 3 moments. In the excitatory stimulated (F3) group, however, the improvement in scores was more expressive between baseline and the second moment, without significant changes in the follow-up.

Conclusions:

The findings of this clinical study suggest that rTMS can be a promising tool, capable of relieving depressive symptoms and helping in the improvement of poststroke patients’ quality of life.

Noninvasive brain stimulation for behavioural and psychological symptoms of dementia: A systematic review and meta-analysis

BACKGROUND

Pharmacological and conventional nonpharmacological treatments for behavioural and psychological symptoms of dementia (BPSD) have only modest efficacy. Furthermore, pharmacotherapy carries the risk of important side effects. Noninvasive brain stimulation (repetitive transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS)) are valuable and safe for cognitive function in Alzheimer disease (AD). However, there have been few studies, and there is no consensus, regarding the use of these techniques to treat BPSD.

METHODS

We performed a systematic review of the literature and meta-analysis of studies reporting the effect of rTMS or tDCS on BPSD.

RESULTS

Seven articles were included: five randomized, controlled clinical trials and two open-label clinical trials. Five studies investigated the effects of rTMS and two the effects of tDCS. Both studies using tDCS reported no evidence of efficacy on BPSD, while two of the three RCTs using rTMS found statistically significant benefits. In an exploratory meta-analysis with four of the RCT studies, we did not find evidence of efficacy of noninvasive brain stimulation techniques, with an overall effect of -0.02 (95% CI = -0.90, 0.94; I²  = 85%). However, when we used only the data from the studies that applied rTMS, we found a positive effect on BPSD, with an overall effect of -0.58 (95% CI = -1.02, -0.14; I²  = 0%). With regards to the adverse effects reported, these were mild and not clinically relevant.

CONCLUSIONS

Our results establish a tendency for efficacy of rTMS protocols on BPSD, while corroborating their safety and tolerability, suggesting the need for further research.

Reduction of intra-abdominal pain through transcranial direct current stimulation: A systematic review

BACKGROUND

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to modulate cortical excitability and to induce neuronal plasticity. With a wide range of applications in neurological and psychiatric disorders, the efficiency of tDCS is also studied in the treatment of various pain conditions. Treatment with tDCS might accordingly provide pain relief for patients with acute or chronic pain and thus lead to an increase in quality of life. Moreover, applied as an adjunct therapy, tDCS can reduce help to reduce pain medication intake and accompanying adverse events. To this end, this review examines studies evaluating the efficacy of tDCS in pain relief in patients with intra-abdominal pain.

METHODS

A structured search of the PubMed medical database was carried out to identify possibly relevant studies. Studies were compared in terms of treatment characteristics, general conditions, and results. Jadad scale was applied for quality analyses.

RESULTS

Out of 289 articles that were found initially, 6 studies were identified that met eligibility criteria. Five out of 6 studies reported significant effects for pain reduction in different types of intra-abdominal pain.

CONCLUSIONS

Results indicate that tDCS might be able to reduce intra-abdominal pain. However, more randomized-controlled trials with larger sample size are necessary to define clinically relevant effects as well as treatment characteristics such as duration of stimulation.

Revisiting the excitation/inhibition imbalance hypothesis of ASD through a clinical lens

Autism spectrum disorder (ASD) currently affects 1 in 59 children, although the aetiology of this disorder remains unknown. Faced with multiple seemingly disparate and noncontiguous neurobiological alterations, Rubenstein and Merzenich hypothesized that imbalances between excitatory and inhibitory neurosignaling (E/I imbalance) underlie ASD. Since this initial statement, there has been a major focus examining this exact topic spanning both clinical and preclinical realms. The purpose of this article is to review the clinical neuroimaging literature surrounding E/I imbalance as an aetiology of ASD. Evidence for E/I imbalance is presented from several complementary clinical techniques including magnetic resonance spectroscopy, magnetoencephalography and transcranial magnetic stimulation. Additionally, two GABAergic potential interventions for ASD, which explicitly attempt to remediate E/I imbalance, are reviewed. The current literature suggests E/I imbalance as a useful framework for discussing the neurobiological etiology of ASD in at least a subset of affected individuals. While not constituting a completely unifying aetiology, E/I imbalance may be relevant as one of several underlying neuropathophysiologies that differentially affect individuals with ASD. Such statements do not diminish the value of the E/I imbalance concept-instead they suggest a possible role for the characterization of E/I imbalance, as well as other underlying neuropathophysiologies, in the biologically-based subtyping of individuals with ASD for potential applications including clinical trial enrichment as well as treatment triage.

[Procognitive effects of transcranial magnetic stimulation in the light of neurocognitive deficit in schizophrenia]

Transcranial magnetic stimulation (TMS) is a relatively new method of non-invasive therapy of mental and neurological diseases that has great potential of therapeutic and diagnostic application. In schizophrenia, TMS may exert a positive effect on cognitive deficit. However this issue remains open. The authors analyze recent studies focused on the dynamics of neurocognitive deficit in TMS therapy and consider clinical effects of TMS in schizophrenia. The analysis has shown that TMS is successfully implemented in treatment of auditory positive symptoms and studies on its effect on negative symptoms of schizophrenia are perspective. Procognitive effect was found in working memory domain, and partially in perception domain within the perception of faces and facial expressions. The data on regulative functions, attention, speech, and nondeclarative memory remains controversial. It has been concluded that further research is needed to clarify the place of TMS in schizophrenia therapy.

Simulation Analyses of tDCS Montages for the Investigation of Dorsal and Ventral Pathways

Modulating higher cognitive functions like reading with transcranial direct current stimulation (tDCS) can be challenging as reading involves regions in the dorsal and ventral cortical areas that lie in close proximity. If the two pathways are stimulated simultaneously, the function of dorsal pathway (predominantly used for graphophonological conversion) might interfere with the function of the ventral pathway (used for semantics), and vice-versa. To achieve functional specificity in tDCS for investigating the two pathways of reading, it is important to stimulate each pathway per session such that the spread of current across the cortical areas due to the two montages has minimal overlap. The present study intends to achieve this by introducing a systematic approach for tDCS analysis. We employed the COMETS2 software to simulate 10 montage configurations (5 for each pathway) for three electrode sizes: 5 × 5, 3 × 3, and 5 × 7 cm2. This diversity in montage configuration is chosen since previous studies found the position and the size of anode and cathode to play an important role. The values of the magnitude of current density (MCD) obtained from the configuration were used to calculate: (i) average MCD in each cortical lobe, (ii) number of overlapping coordinates, and (iii) cortical areas with high MCD. The measures (i) and (iii) ascertained the current spread by each montage within a cortical lobe, and (ii) verified the overlap of the spread of current between a pair of montages. The analyses show that a montage using the electrode size of 5 × 5 cm2 with the anode at CP5 and cathode at CZ, and another with anode at TP7 and cathode at nape of the neck are optimal choices for dorsal and ventral pathways, respectively. To verify, we cross-validated the results with ROAST. This systematic approach was helpful in reducing the ambiguity of montage selection prior to conducting a tDCS study.

Effects of Repetitive Transcranial Magnetic Stimulation on Walking and Balance Function after Stroke: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of this study was to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on walking and balance function in patients with stroke.

DESIGN

MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science, CENTRAL, and the Physiotherapy Evidence Database were comprehensively searched for randomized controlled trials published through March 2017 that investigated the effects of rTMS on lower limb function. Main outcomes included walking speed, balance function, motor function, and cortical excitability.

RESULTS

Nine studies were included. The meta-analysis revealed a significant effect of rTMS on walking speed (standardized mean difference, 0.64; 95% confidence interval [CI], 0.32-0.95), particularly ipsilesional stimulation (standardized mean difference, 0.80; 95% CI, 0.36-1.24). No significant effects were found for balance function (standardized mean difference, 0.10; 95% CI, -0.26 to 0.45), motor function (mean difference, 0.50, 95% CI: -0.68 to 1.68), or cortical excitability (motor-evoked potentials of the affected hemisphere: mean difference, 0.21 mV; 95% CI, -0.11 to 0.54; motor-evoked potentials of the unaffected hemisphere: mean difference, 0.09 mV; 95% CI, -0.16 to -0.02).

CONCLUSION

These results suggest that rTMS, particularly ipsilesional stimulation, significantly improves walking speed. Future studies with larger sample sizes and an adequate follow-up period are required to further understand the effects of rTMS on lower limb function and its relationship with changes in cortical excitability with the help of functional neuroimaging techniques.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: 1) Understand the potential neurophysiologic effects of rTMS; 2) Appreciate the potential benefits of rTMS on stroke recovery; and 3) Identify indications for including rTMS in a stroke rehabilitation program.

LEVEL

Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

The effect of psychotropic drugs on cortical excitability and plasticity measured with transcranial magnetic stimulation: Implications for psychiatric treatment

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) is an emerging treatment for neuropsychiatric disorders. Patients in rTMS treatment typically receive concomitant psychotropic medications, which affect neuronal excitability and plasticity and may interact to affect rTMS treatment outcomes. A greater understanding of these drug effects may have considerable implications for optimizing multi-modal treatment of psychiatric patients, and elucidating the mechanism(s) of action (MOA) of rTMS.

METHOD

We summarized the empirical literature that tests how psychotropic drugs affect cortical excitability and plasticity, using varied experimental TMS paradigms.

RESULTS

Glutamate antagonists robustly attenuate plasticity, largely without changes in excitability per se; antiepileptic drugs show the opposite pattern of effects, while calcium channel blockers attenuate plasticity. Benzodiazepines have moderate and variable effects on plasticity, and negligible effects on excitability. Antidepressants with potent 5HT transporter inhibition reduce both excitability and alter plasticity, while antidepressants with other MOAs generally lack either effect. Catecholaminergic drugs, cholinergic agents and lithium have minimal effects on excitability but exhibit robust and complex, non-linear effects in TMS plasticity paradigms.

LIMITATIONS

These effects remain largely untested in sustained treatment protocols, nor in clinical populations. In addition, how these medications impact clinical response to rTMS remains largely unknown.

CONCLUSIONS

Psychotropic medications exert robust and varied effects on cortical excitability and plasticity. We encourage the field to more directly and fully investigate clinical pharmaco-TMS studies to improve outcomes.

Unraveling Causal Mechanisms of Top-Down and Bottom-Up Visuospatial Attention with Non-invasive Brain Stimulation

Attention is a process of selection that allows us to intelligently navigate the abundance of information in our world. Attention can be either directed voluntarily based on internal goals-"top-down" or goal-directed attention-or captured automatically, by salient stimuli-"bottom-up" or stimulus-driven attention. Do these two modes of attention control arise from same or different brain circuits? Do they share similar or distinct neural mechanisms? In this review, we explore this dichotomy between the neural bases of top-down and bottom-up attention control, with a special emphasis on insights gained from non-invasive neurostimulation techniques, specifically, transcranial magnetic stimulation (TMS). TMS enables spatially focal and temporally precise manipulation of brain activity. We explore a significant literature devoted to investigating the role of fronto-parietal brain regions in top-down and bottom-up attention with TMS, and highlight key areas of convergence and debate. We also discuss recent advances in combinatorial paradigms that combine TMS with other imaging modalities, such as functional magnetic resonance imaging or electroencephalography. These paradigms are beginning to bridge essential gaps in our understanding of the neural pathways by which TMS affects behavior, and will prove invaluable for unraveling mechanisms of attention control, both in health and in disease.

Neural effects of transcranial magnetic stimulation at the single-cell level

Transcranial magnetic stimulation (TMS) can non-invasively modulate neural activity in humans. Despite three decades of research, the spatial extent of the cortical area activated by TMS is still controversial. Moreover, how TMS interacts with task-related activity during motor behavior is unknown. Here, we applied single-pulse TMS over macaque parietal cortex while recording single-unit activity at various distances from the center of stimulation during grasping. The spatial extent of TMS-induced activation is remarkably restricted, affecting the spiking activity of single neurons in an area of cortex measuring less than 2 mm in diameter. In task-related neurons, TMS evokes a transient excitation followed by reduced activity, paralleled by a significantly longer grasping time. Furthermore, TMS-induced activity and task-related activity do not summate in single neurons. These results furnish crucial experimental evidence for the neural effects of TMS at the single-cell level and uncover the neural underpinnings of behavioral effects of TMS.

Transcranial Magnetic Stimulation (TMS) can modulate human brain activity, but the extent of the cortical area activated by TMS is unclear. Here, the authors show that TMS affects monkey single neuron activity in an area less than 2 mm diameter, while TMS-induced activity and task-related activity do not summate.

Is tDCS an Adjunct Ergogenic Resource for Improving Muscular Strength and Endurance Performance? A Systematic Review

Exercise performance is influenced by many physical factors, such as muscle strength and endurance. Particularly in the physical fitness and sports performance contexts, there are many types of ergogenic aids to improve muscular strength and endurance performance, with non-athletes and even athletes using illegal drugs to reach the top. Thus, the development of innovative methods to aid in exercise performance is of great interest. One such method is transcranial direct current stimulation (tDCS). A systematic search was performed on the following databases, until January 2019; PubMed/MEDLINE, SCOPUS, and Pedro database. Studies on tDCS for muscular strength and endurance performance improvement in non-athletes and athletes adults were included. We compared the effect of anodal-tDCS (a-tDCS) to a sham/control condition on the outcomes muscular strength and endurance performance. We found 26 controlled trials. No trial mentions negative side effects of the intervention. The data show differences between the studies investigating muscle strength and the studies evaluating endurance, with regard to successful use of tDCS. Studies investigating the efficiency of tDCS on improving muscular strength demonstrate positive effects of a-tDCS in 66.7% of parameters tested. In contrast, in studies evaluating the effects of a-tDCS on improving endurance performance the a-tDCS revealed a significant improvement in only 50% of parameters assessed. The majority of the data shows consistently influence of a-tDCS on muscular strength, but not to endurance performance. The results of this systematic review suggest that a-tDCS can improve muscular strength, but not to endurance performance.

Motor cortical plasticity in schizophrenia: A meta-analysis of Transcranial Magnetic Stimulation - Electromyography studies

BACKGROUND

Several lines of investigations converge upon aberrant synaptic plasticity as a potential pathophysiological characteristic of schizophrenia. In vivo experiments using neuromodulatory perturbation techniques like Transcranial Magnetic and Direct Current Stimulation (TMS & tDCS) have been increasingly used to measure 'motor cortical plasticity' in schizophrenia. A systematic quantification of cortical plasticity and its moderators in schizophrenia is however lacking.

METHOD

The PubMed/MEDLINE database was searched for studies up to December 31st, 2017 that examined case-control experiments comparing neuromodulation following single-session of TMS or tDCS. The primary outcome was the standardized mean difference for differential changes in motor evoked potential (MEP) amplitudes measured with single-pulse TMS (MEP Δ) between patients and healthy subjects following TMS or tDCS. After examining heterogeneity, meta-analyses were performed using fixed effects models.

RESULTS

A total of 16 datasets comparing cortical plasticity (MEP Δ) between 189 schizophrenia patients and 187 healthy controls were included in the meta-analysis. Patients demonstrated diminished MEP Δ with effect sizes (Cohen's d) ranging from 0.66 (LTP-like plasticity) to 0.68 (LTD-like plasticity). Heterosynaptic plasticity studies demonstrated a greater effect size (0.79) compared to homosynaptic plasticity studies (0.62), though not significant (P = 0.43). Clinical, perturbation protocol- and measurement-related factors, and study quality did not significantly moderate the aberrant plasticity demonstrated in schizophrenia.

CONCLUSIONS

Schizophrenia patients demonstrate diminished LTP- and LTD-like motor cortical plasticity, which is not influenced by the various clinical and experimental protocol related confounders. These consistent findings should encourage the use of perturbation-based biomarkers to characterize illness trajectories and treatment response.

A Novel Racing Array Transducer for Noninvasive Ultrasonic Retinal Stimulation: A Simulation Study

Neurostimulation has proved to be an effective method for the restoration of visual perception lost due to retinal diseases. However, the clinically available retinal neurostimulation method is based on invasive electrodes, making it a high-cost and high-risk procedure. Recently, ultrasound has been demonstrated to be an effective way to achieve noninvasive neurostimulation. In this work, a novel racing array transducer with a contact lens shape is proposed for ultrasonic retinal stimulation. The transducer is flexible and placed outside the eyeball, similar to the application of a contact lens. Ultrasound emitted from the transducer can reach the retina without passing through the lens, thus greatly minimizing the acoustic absorption in the lens. The discretized Rayleigh–Sommerfeld method was employed for the acoustic field simulation, and patterned stimulation was achieved. A 5 MHz racing array transducer with different element numbers was simulated to optimize the array configuration. The results show that a 512-element racing array is the most appropriate configuration considering the necessary tradeoff between the element number and the stimulation resolution. The stimulation resolution at a focus of 24 mm is about 0.6 mm. The obtained results indicate that the proposed racing array design of the ultrasound transducer can improve the feasibility of an ultrasound retinal prosthesis.

Non-invasive Brain Stimulation in Pediatric Migraine: A Perspective From Evidence in Adult Migraine

Pediatric migraine remains still a challenge for the headache specialists as concerns both diagnostic and therapeutic aspects. The less ability of children to describe the exact features of their migraines and the lack of reliable biomarker for migraine contribute to complicate the diagnostic process. Therefore, there's need for new effective tools for supporting diagnostic and therapeutic approach in children with migraine. Recently, promising results have been obtained in adult headache by means of application of neurostimulation techniques both for investigating pathophysiological mechanisms and also for therapeutical applications. Non-invasive brain stimulation (NIBS) techniques like transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) indeed proved to be generally safe and showing also some evidence of efficacy particularly for the symptomatic treatment. On such basis, in the last years increasing interest is rising in scientific pediatric community to evaluate the potential of such approaches for treatment pediatric headaches, particularly in migraine, even if the evidence provided is still very poor. Here we present a perspective for application of TMS and tDCS technique in children migraine principally based on evidence coming by studies in adults.

Magnetic Strategies for Nervous System Control

Magnetic fields pass through tissue undiminished and without producing harmful effects, motivating their use as a wireless, minimally invasive means to control neural activity. Here, we review mechanisms and techniques coupling magnetic fields to changes in electrochemical potentials across neuronal membranes. Biological magnetoreception, although incompletely understood, is discussed as a potential source of inspiration. The emergence of magnetic properties in materials is reviewed to clarify the distinction between biomolecules containing transition metals and ferrite nanoparticles that exhibit significant net moments. We describe recent developments in the use of magnetic nanomaterials as transducers converting magnetic stimuli to forms readily perceived by neurons and discuss opportunities for multiplexed and bidirectional control as well as the challenges posed by delivery to the brain. The variety of magnetic field conditions and mechanisms by which they can be coupled to neuronal signaling cascades highlights the desirability of continued interchange between magnetism physics and neurobiology.

Designing and Implementing a Novel Transcranial Electrostimulation System for Neuroplastic Applications: A Preliminary Study

Recently, a specific repetitive transcranial magnetic stimulation (rTMS) waveform, namely, the theta burst stimulation (TBS) protocol, has been proposed for more efficiently inducing neuroplasticity for various clinic rehabilitation purposes. However, few studies have explored the feasibility of using the TBS combined with direct current (dc) waveform for brain neuromodulation; this waveform is transcranially delivered using electrical current power rather than magnetic power. This study implemented a prototype of a novel transcranial electrostimulation device that can flexibly output a waveform that combined dc and the TBS-like protocol and assessed the effects of the novel combinational waveform on neuroplasticity. An in vivo experiment was conducted first to validate the accuracy of the stimulator's current output at various impedance loads. Using this transcranial stimulator, a series of transcranial stimulation experiments was conducted on the brain cortex of rats, in which electrode-tissue impedance and motor evoked potentials (MEPs) were measured. These experiments were designed to assess the feasibility and efficacy of the new combinational waveforms for brain neuroplasticity. Our results indicated that the transcranial electrostimulation system exhibited satisfactory performance, as evidenced by the error percentage of less than 5% for current output. In the animal experiment, the dc combined with intermittent TBS-like protocol exerted a stronger neuroplastic effect than the conventional dc protocol. These results demonstrated that the combination of electrical dc and TBS-like protocols in our system can produce a new feasible therapeutic waveform for transcranially inducing a promising neuromodulatory effect on various diseases of the central nervous system.

Therapeutic Systems and Technologies: State-of-the-Art Applications, Opportunities, and Challenges

In this review, we present current state-of-the-art developments and challenges in the areas of thermal therapy, ultrasound tomography, image-guided therapies, ocular drug delivery, and robotic devices in neurorehabilitation. Additionally, intellectual property and regulatory aspects pertaining to therapeutic systems and technologies are addressed.

The Dynamic Duo: Combining noninvasive brain stimulation with cognitive interventions

Pharmacotherapy, psychotherapy, and non-invasive brain stimulation (NIBS)¹ each show efficacy in the treatment of psychiatric disorders; however, more efficacious interventions are needed as reflected by an overall unmet need in mental health care. While each modality has typically been studied and developed as a monotherapy, in practice they are typically used in combination. Research has begun to emerge studying the potential synergistic actions of multi-modal, combination therapies. For example, NIBS combined with rehabilitation strategies have demonstrated some success for speech and motor rehabilitation in stroke patients. In this review we present evidence suggesting that combining NIBS with targeted, cognitive interventions offers a potentially powerful new approach to treating neuropsychiatric disorders. Here we focus on NIBS studies using transcranial direct current stimulation (tDCS)² and transcranial magnetic stimulation (TMS)³ given that these modalities are relatively safe, noninvasive, and can be performed simultaneously with neurocognitive interventions. We review the concept of "state dependent" effects of NIBS and highlight how simultaneous or sequential cognitive interventions could help optimize NIBS therapy by providing further control of ongoing neural activity in targeted neural networks. This review spans a range of neuropsychiatric disorders including major depressive disorder, schizophrenia, generalized anxiety, and autism. For each disorder, we emphasize neuroanatomical circuitry that could be engaged with combination therapy and critically discuss the literature that has begun to emerge. Finally, we present possible underlying mechanisms and propose future research strategies that may further refine the potential of combination therapies.

Self-Powered Well-Aligned P(VDF-TrFE) Piezoelectric Nanofiber Nanogenerator for Modulating an Exact Electrical Stimulation and Enhancing the Proliferation of Preosteoblasts

Electric potential plays an indispensable role in tissue engineering and wound healing. Piezoelectric nanogenerators based on direct piezoelectric effects can be self-powered energy sources for electrical stimulation and have attracted extensive attention. However, the accuracy of piezoelectric stimuli on piezoelectric polymers membranes in vitro during the dynamic condition is rarely studied. Here, a self-powered tunable electrical stimulation system for assisting the proliferation of preosteoblasts was achieved by well-aligned P(VDF-TrFE) piezoelectric nanofiber membrane (NFM) both as a nanogenerator (NG) and as a scaffold. The effects of electrospinning and different post-treatments (annealing and poling) on the surface wettability, piezoelectric β phase, ferroelectric properties, and sensing performance of NFMs were evaluated here. The polarized P(VDF-TrFE) NFM offered an enhanced piezoelectric value (d31 of 22.88 pC/N) versus pristine P(VDF-TrFE) NFM (d31 of 0.03 pC/N) and exhibited good sensing performance. The maximum voltage and current output of the P(VDF-TrFE) piezoelectric nanofiber NGs reached -1.7 V and 41.5 nA, respectively. An accurate electrical response was obtained in real time under dynamic mechanical stimulation by immobilizing the NGs on the flexible bottom of the culture plate, thereby restoring the real scene of providing electrical stimulation to the cells in vitro. In addition, we simulated the interaction between the piezoelectric nanofiber NG and cells through an equivalent circuit model. To verify the feasibility of P(VDF-TrFE) nanofiber NGs as an exact electrical stimulation, the effects of different outputs of P(VDF-TrFE) nanofiber NGs on cell proliferation in vitro were compared. The study realized a significant enhancement of preosteoblasts proliferation. This work demonstrated the customizability of P(VDF-TrFE) piezoelectric nanofiber NG for self-powered electrical stimulation system application and suggested its significant potential application for tissue repair and regeneration.

Accelerated transcranial magnetic stimulation for the treatment of Patients with depression: A review

Major depressive disorder is a highly prevalent and profoundly disabling psychiatric disorder with significant morbidity and mortality and it is very often resistant to antidepressants, electroconvulsive therapy and psychotherapy. Therapeutic alternatives include repetitive transcranial magnetic stimulation which may be an effective choice for treatment-resistant depression but requires prolonged treatments for at least four to six weeks. Shorter exposure to this technique might be more advantageous for certain cases. The purpose of this review is to describe and discuss studies that have evaluated the safety and efficacy of accelerated transcranial magnetic stimulation (aTMS) in the acute treatment of depression. Methods: The electronic literature (NCBI Pubmed; Science Direct) on aTMS for the treatment of depression was reviewed. In the last years, a limited number of controlled and open-label studies have been published on the subject. The majority of these studies have shown promising results with aTMS, this protocol probably being at least as safe and as efficacious as conventional rTMS (five sessions per week) in the treatment of treatment-resistant depression (TRD) with a trend for faster response rates when more intensive protocols are used (15 sessions over two days). Future well-designed sham-controlled studies with larger samples are needed to confirm the safety and efficacy of aTMS in the treatment of depression.

Ventral prefrontal cortex and emotion regulation in aging: A case for utilizing transcranial magnetic stimulation

OBJECTIVES

The ventrolateral prefrontal cortex (vlPFC) has been speculated to play an important role in complex processes that allow emotional factors to influence human cognition. Accumulating evidence from human neuroimaging studies, in conjunction with studies of patients with lesions and animal models, shed light on the role of the vlPFC in emotion regulation (ER). This review aims to discuss and integrate recent findings related to vlPFC's role in ER in the context of aging, drawing from diverse sources, and suggest future directions for research utilizing transcranial magnetic stimulation (TMS).

METHODS/DESIGN

We summarize findings from the existing literature investigating the neural basis of frontal-lobe mediated ER and then highlight major findings from recent studies directly comparing healthy younger and older adult groups. We conclude by pointing to unaddressed questions worth pursuing in future research.

RESULTS AND DISCUSSION

We propose future research directions utilizing TMS to answer key unaddressed questions. Moreover, we discuss the potential advantages, challenges, and limitations of using TMS as a complement to the existing neuroimaging methods in ER.

Pilot study of feasibility and effect of anodal transcutaneous spinal direct current stimulation on chronic neuropathic pain after spinal cord injury

STUDY DESIGN

A single-blind crossover study.

OBJECTIVES

This study aimed to evaluate neuropathic pain in persons with spinal cord injury (SCI) after the application of transcutaneous spinal direct current stimulation (tsDCS).

SETTING

Outpatient Clinic of the Rehabilitation Department, Seoul National University Hospital.

METHODS

The effect of single sessions of both anodal and sham tsDCS (2 mA, 20 min) on chronic neuropathic pain in ten volunteers with complete motor cervical SCI was assessed. The active electrode was placed over the spinal process of the tenth thoracic vertebra and the reference electrode, at the top of the head. Pre- to post-tsDCS intervention changes in pain intensity (numeric rating scale, NRS), patient global assessment, and present pain intensity (PPI) were assessed before and after the tsDCS session (immediately post stimulation, and at 1 and 2 h post stimulation).

RESULTS

All participants underwent the stimulation procedure without dropout. Our results showed no significant pre- to post-treatment difference in pain intensity between the active and sham tsDCS groups. Only in the sham tsDCS stimulation, NRS and PPI scores were reduced after the stimulation session. Furthermore, in the mixed effect model analysis, the response in the second period appeared to be more favorable.

CONCLUSION

The results suggest that a single session of anodal tsDCS with the montage used in this study is feasible but does not have a significant analgesic effect in individuals with chronic cervical SCI.

SPONSORSHIP

The study was funded by Seoul National University Hospital (No. 0420160470) and Korea Workers' Compensation & Welfare Service.

Magnetic stimulation of carotid sinus as a treatment for hypertension

Previously, we reported that magnetic stimulation of carotid sinus (MSCS) could lower arterial pressure in rabbits. In this randomized, sham-controlled pilot study, we evaluated the effects of MSCS on blood pressure in pre-hypertensive and hypertensive subjects. A total of 15 subjects with blood pressure higher than 130/80 mm Hg were randomized to receive sham or 1Hz MSCS. The changes of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MAP) during treatment were compared between groups. The heart rate variability (HRV) and baroreflex sensitivity (BRS) before, during, and after treatments were analyzed. Reduction of SBP was significantly greater in subjects with MSCS than those with sham stimulation (6.6 ± 0.4 vs -2.5 ± 0.4 mm Hg, P < 0.001). Reduction of DBP was significantly greater in subjects with MSCS than those with sham stimulation (1.2 ± 0.2 vs -2.8 ± 0.2 mm Hg, P < 0.001). Reduction of MAP was significantly greater in subjects with MSCS than those with sham stimulation (1.4 ± 0.3 mm Hg vs -4.0 ± 0.3 mm Hg, P < 0.001). Reduction of HR was significantly greater in subjects with MSCS than those with sham stimulation (0.5 ± 0.5 vs -1.9 ± 0.3 beats/min, P = 0.002). BRS increased from 6.85 ± 0.77 to 8.79 ± 0.95 ms/mm Hg after MSCS compared with that at baseline (P = 0.027). Thus, MSCS can lower blood pressure and heart rate in pre-hypertensive and hypertensive subject, warranting further study for establishing MSCS as a treatment for hypertension.

Prefrontal brain stimulation during food-related inhibition training: effects on food craving, food consumption and inhibitory control

Modulation of dorsolateral prefrontal cortex (DLPFC) activity using non-invasive brain stimulation has been shown to reduce food craving as well as food consumption. Using a preregistered design, we examined whether bilateral transcranial direct current stimulation (tDCS) of the DLPFC could reduce food craving and consumption in healthy participants when administered alongside the cognitive target of inhibitory control training. Participants (N = 172) received either active or sham tDCS (2 mA; anode F4, cathode F3) while completing a food-related Go/No-Go task. State food craving, ad-lib food consumption and response inhibition were evaluated. Compared with sham stimulation, we found no evidence for an effect of active tDCS on any of these outcome measures in a predominantly female sample. Our findings raise doubts about the effectiveness of single-session tDCS on food craving and consumption. Consideration of individual differences, improvements in tDCS protocols and multi-session testing are discussed.

A MEMS ultrasound stimulation system for modulation of neural circuits with high spatial resolution in vitro

Neuromodulation by ultrasound has recently received attention due to its noninvasive stimulation capability for treating brain diseases. Although there have been several studies related to ultrasonic neuromodulation, these studies have suffered from poor spatial resolution of the ultrasound and low repeatability with a fixed condition caused by conventional and commercialized ultrasound transducers. In addition, the underlying physics and mechanisms of ultrasonic neuromodulation are still unknown. To determine these mechanisms and accurately modulate neural circuits, researchers must have a precisely controllable ultrasound transducer to conduct experiments at the cellular level. Herein, we introduce a new MEMS ultrasound stimulation system for modulating neurons or brain slices with high spatial resolution. The piezoelectric micromachined ultrasonic transducers (pMUTs) with small membranes (sub-mm membranes) generate enough power to stimulate neurons and enable precise modulation of neural circuits. We designed the ultrasound transducer as an array structure to enable localized modulation in the target region. In addition, we integrated a cell culture chamber with the system to make it compatible with conventional cell-based experiments, such as in vitro cell cultures and brain slices. In this work, we successfully demonstrated the functionality of the system by showing that the number of responding cells is proportional to the acoustic intensity of the applied ultrasound. We also demonstrated localized stimulation capability with high spatial resolution by conducting experiments in which cocultured cells responded only around a working transducer.