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1

Neuromodulation for Neuropsychiatric Disorders: Novel Techniques Vagus Nerve Stimulation, Transcranial Magnetic Stimulation, Transcranial Direct Current Stimulation, and Deep Brain Stimulation  

Microsoft Academic Search

\\u000a The last two decades have seen the development of several neuromodulation techniques that have been applied to the problem\\u000a of severe, medication-refractory depression – notably vagus nerve stimulation, transcranial magnetic stimulation, transcranial\\u000a direct current stimulation, and deep brain stimulation. The four techniques are here reviewed from the standpoint of the hardware\\u000a involved, the techniques of application, the biological effects of

Russell J. Andrews

2

Calculating the induced electromagnetic fields in real human head by deep transcranial magnetic stimulation.  

PubMed

Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) may be beneficial in the treatment of several neurological and psychiatric disorders. This paper presents numerical simulation of deep transcranial magnetic stimulation (dTMS) by considering double cone, H-and Halo coils. Three-dimensional distributions of the induced fields i.e. magnetic flux density, current density and electric fields in realistic head model by dTMS coils were calculated by impedance method and the results were compared with that of figure-of-eight coil. It was found that double cone and H-coils have significantly deep field penetration at the expense of induced higher and wider spread electrical fields in superficial cortical regions. The Halo coil working with a circular coil carrying currents in opposite directions provides a flexible way to stimulate deep brain structures with much lower stimulation in superficial brain tissues. PMID:24109807

Lu, Mai; Ueno, Shoogo

2013-01-01

3

Neuromodulation for depression: invasive and noninvasive (deep brain stimulation, transcranial magnetic stimulation, trigeminal nerve stimulation).  

PubMed

Major depressive disorder is among the most disabling illnesses and, despite best practices with medication and psychotherapy, many patients remain ill even after several treatment trials. For many of these patients with treatment-resistant or pharmacoresistant depression, treatment with neuromodulation offers an alternative. Options range from systems that are implanted to others that are entirely noninvasive. This review surveys recent literature to update readers on 3 particular interventions: deep brain stimulation, transcranial magnetic stimulation, and trigeminal nerve stimulation. Additional comparative research is needed to delineate the relative advantages of these treatments, and how best to match individual patients to neuromodulation intervention. PMID:24262903

Cook, Ian A; Espinoza, Randall; Leuchter, Andrew F

2014-01-01

4

Neuroprotection trek--the next generation: neuromodulation I. Techniques--deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation  

NASA Technical Reports Server (NTRS)

Neuromodulation denotes controlled electrical stimulation of the central or peripheral nervous system. The three forms of neuromodulation described in this paper-deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation-were chosen primarily for their demonstrated or potential clinical usefulness. Deep brain stimulation is a completely implanted technique for improving movement disorders, such as Parkinson's disease, by very focal electrical stimulation of the brain-a technique that employs well-established hardware (electrode and pulse generator/battery). Vagus nerve stimulation is similar to deep brain stimulation in being well-established (for the treatment of refractory epilepsy), completely implanted, and having hardware that can be considered standard at the present time. Vagus nerve stimulation differs from deep brain stimulation, however, in that afferent stimulation of the vagus nerve results in diffuse effects on many regions throughout the brain. Although use of deep brain stimulation for applications beyond movement disorders will no doubt involve placing the stimulating electrode(s) in regions other than the thalamus, subthalamus, or globus pallidus, the use of vagus nerve stimulation for applications beyond epilepsy-for example, depression and eating disorders-is unlikely to require altering the hardware significantly (although stimulation protocols may differ). Transcranial magnetic stimulation is an example of an external or non-implanted, intermittent (at least given the current state of the hardware) stimulation technique, the clinical value of which for neuromodulation and neuroprotection remains to be determined.

Andrews, Russell J.

2003-01-01

5

Maintenance Deep Transcranial Magnetic Stimulation Sessions are Associated with Reduced Depressive Relapses in Patients with Unipolar or Bipolar Depression  

PubMed Central

Introduction: Deep transcranial magnetic stimulation (dTMS) is a new form of TMS allowing safe stimulation of deep brain regions. The objective of this preliminary study was to assess the role of dTMS maintenance sessions in protecting patients with bipolar disorder (BD) or recurrent major depressive disorder (MDD) from developing depressive or manic relapses in a 12-month follow-up period. Methods: Twenty-four drug-resistant patients with a current depressive episode and a diagnosis of MDD or BD have been enrolled in the study. All the participants underwent daily dTMS sessions for 4?weeks. One group (maintenance – M group) received additional maintenance dTMS sessions weekly or twice a week. Results: After the first dTMS cycle, a significant reduction of Hamilton Depression Rating Scale (HDRS) scores was observed in all participants. Subsequently, the HDRS mean scores did not significantly change over time in the M group, while it significantly increased in the non-M-group after 6 and 12?months. Discussion: This study confirms previous evidence of a positive therapeutic effect of dTMS on depressive symptoms and suggests that, after recovery from acute episodes, maintenance dTMS sessions may be helpful in maintaining euthymia in a 12-month follow-up period. PMID:25709596

Rapinesi, Chiara; Bersani, Francesco Saverio; Kotzalidis, Georgios D.; Imperatori, Claudio; Del Casale, Antonio; Di Pietro, Simone; Ferri, Vittoria R.; Serata, Daniele; Raccah, Ruggero N.; Zangen, Abraham; Angeletti, Gloria; Girardi, Paolo

2015-01-01

6

Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial.  

PubMed

Major depressive disorder (MDD) is a prevalent and disabling condition, and many patients do not respond to available treatments. Deep transcranial magnetic stimulation (dTMS) is a new technology allowing non-surgical stimulation of relatively deep brain areas. This is the first double-blind randomized controlled multicenter study evaluating the efficacy and safety of dTMS in MDD. We recruited 212 MDD outpatients, aged 22-68 years, who had either failed one to four antidepressant trials or not tolerated at least two antidepressant treatments during the current episode. They were randomly assigned to monotherapy with active or sham dTMS. Twenty sessions of dTMS (18 Hz over the prefrontal cortex) were applied during 4 weeks acutely, and then biweekly for 12 weeks. Primary and secondary efficacy endpoints were the change in the Hamilton Depression Rating Scale (HDRS-21) score and response/remission rates at week 5, respectively. dTMS induced a 6.39 point improvement in HDRS-21 scores, while a 3.28 point improvement was observed in the sham group (p=0.008), resulting in a 0.76 effect size. Response and remission rates were higher in the dTMS than in the sham group (response: 38.4 vs. 21.4%, p=0.013; remission: 32.6 vs. 14.6%, p=0.005). These differences between active and sham treatment were stable during the 12-week maintenance phase. dTMS was associated with few and minor side effects apart from one seizure in a patient where a protocol violation occurred. These results suggest that dTMS constitutes a novel intervention in MDD, which is efficacious and safe in patients not responding to antidepressant medications, and whose effect remains stable over 3 months of maintenance treatment. PMID:25655160

Levkovitz, Yechiel; Isserles, Moshe; Padberg, Frank; Lisanby, Sarah H; Bystritsky, Alexander; Xia, Guohua; Tendler, Aron; Daskalakis, Zafiris J; Winston, Jaron L; Dannon, Pinhas; Hafez, Hisham M; Reti, Irving M; Morales, Oscar G; Schlaepfer, Thomas E; Hollander, Eric; Berman, Joshua A; Husain, Mustafa M; Sofer, Uzi; Stein, Ahava; Adler, Shmulik; Deutsch, Lisa; Deutsch, Frederic; Roth, Yiftach; George, Mark S; Zangen, Abraham

2015-02-01

7

Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial  

PubMed Central

Major depressive disorder (MDD) is a prevalent and disabling condition, and many patients do not respond to available treatments. Deep transcranial magnetic stimulation (dTMS) is a new technology allowing non-surgical stimulation of relatively deep brain areas. This is the first double-blind randomized controlled multicenter study evaluating the efficacy and safety of dTMS in MDD. We recruited 212 MDD outpatients, aged 22–68 years, who had either failed one to four antidepressant trials or not tolerated at least two antidepressant treatments during the current episode. They were randomly assigned to monotherapy with active or sham dTMS. Twenty sessions of dTMS (18 Hz over the prefrontal cortex) were applied during 4 weeks acutely, and then biweekly for 12 weeks. Primary and secondary efficacy endpoints were the change in the Hamilton Depression Rating Scale (HDRS-21) score and response/remission rates at week 5, respectively. dTMS induced a 6.39 point improvement in HDRS-21 scores, while a 3.28 point improvement was observed in the sham group (p+0.008), resulting in a 0.76 effect size. Response and remission rates were higher in the dTMS than in the sham group (response: 38.4 vs. 21.4%, p+0.013; remission: 32.6 vs. 14.6%, p+0.005). These differences between active and sham treatment were stable during the 12-week maintenance phase. dTMS was associated with few and minor side effects apart from one seizure in a patient where a protocol violation occurred. These results suggest that dTMS constitutes a novel intervention in MDD, which is efficacious and safe in patients not responding to antidepressant medications, and whose effect remains stable over 3 months of maintenance treatment. PMID:25655160

Levkovitz, Yechiel; Isserles, Moshe; Padberg, Frank; Lisanby, Sarah H; Bystritsky, Alexander; Xia, Guohua; Tendler, Aron; Daskalakis, Zafiris J; Winston, Jaron L; Dannon, Pinhas; Hafez, Hisham M; Reti, Irving M; Morales, Oscar G; Schlaepfer, Thomas E; Hollander, Eric; Berman, Joshua A; Husain, Mustafa M; Sofer, Uzi; Stein, Ahava; Adler, Shmulik; Deutsch, Lisa; Deutsch, Frederic; Roth, Yiftach; George, Mark S; Zangen, Abraham

2015-01-01

8

Transcranial magnetic stimulation in children  

Microsoft Academic Search

Developmental disabilities (e.g. attention deficit disorder; cerebral palsy) are frequently associated with deviations of the typical pattern of motor skill maturation. Neurophysiologic tools, such as transcranial magnetic stimulation (TMS), which probe motor cortex function, can potentially provide insights into both typical neuromotor maturation and the mechanisms underlying the motor skill deficits in children with developmental disabilities. These insights may set

Marjorie A. Garvey; Volker Mall

2008-01-01

9

Original Research Cerebellar Transcranial Magnetic Stimulation: The Role of Coil  

E-print Network

Keywords: Cerebellum TMS Cerebello brain inhibition Cerebellar brain inhibition TMS coil geometry Deep TMS magnetic stimulation (TMS) coil geometry has important effects on the evoked magnetic field, no study has cerebellar TMS studies. Ã? 2014 Elsevier Inc. All rights reserved. Introduction Transcranial magnetic

Miall, Chris

10

Neural correlates of clinical improvement after deep transcranial magnetic stimulation (DTMS) for treatment-resistant depression: a case report using functional magnetic resonance imaging.  

PubMed

We report the effects of a 4-week trial of deep transcranial magnetic stimulation (DTMS) on depressive and anxious symptoms and brain activity in a patient (Mrs A) with treatment-resistant depression (TRD). The protocol involved a pre- and a post-functional magnetic resonance imaging (fMRI) scan during which Mrs A had to perform a working memory task (i.e., n-back). Her baseline score on the 21-item Hamilton Depression Rating Scale (HAM-D21) was 24, indicating severe depressive symptoms. Immediately after 4 weeks of daily DTMS treatment applied over the left dorsolateral prefrontal cortex (DLPFC), her HAM-D21 score decreased to 13 (a 46% reduction), and 1 month later, it was 12 (a 50% reduction). Moreover, Mrs A's accuracy scores on the n-back task (i.e., 2-back condition) improved from 79% (baseline) to 96% (after DTMS treatment). At the neural level, Mrs A showed significantly increased brain activity in the working memory network (e.g., DLPFC, parietal cortex) during the execution of the 2-back condition after DTMS treatment compared to baseline. PMID:24313336

Harvey, Philippe-Olivier; Van den Eynde, Frederique; Zangen, Abraham; Berlim, Marcelo T

2015-02-01

11

Transcranial magnetic stimulation and cognitive neuroscience  

Microsoft Academic Search

Transcranial magnetic stimulation has been used to investigate almost all areas of cognitive neuroscience. This article discusses the most important (and least understood) considerations regarding the use of transcranial magnetic stimulation for cognitive neuroscience and outlines advances in the use of this technique for the replication and extension of findings from neuropsychology. We also take a more speculative look forward

Vincent Walsh; Alan Cowey

2000-01-01

12

Optimization of multiple coils immersed in a conducting liquid for half-hemisphere or whole-brain deep transcranial magnetic stimulation: A simulation study.  

PubMed

Transcranial magnetic stimulation (TMS) was proposed in 1985. Nevertheless, its wider use in the treatment of several neurologic diseases has been hindered by its inability to stimulate deep-brain regions. This is mainly due to the physical limiting effect arising from the presence of surface discontinuities, particularly between the scalp and air. Here, we present the optimization of a system of large multiple coils for whole-brain and half-hemisphere deep TMS, termed orthogonal configuration. COMSOL(®)-based simulations show that the system is capable of reaching the very center of a spherical brain phantom with 58% induction relative to surface maximum. Such penetration capability surpasses to the best of our knowledge that of existing state of the art TMS systems. This induction capability strongly relies on the immersion of the stimulating coils and part of the head of the patient in a conducting liquid (e.g. simple saline solution). We show the impact of the presence of this surrounding conducting liquid by comparing the performance of our system with and without such liquid. In addition, we also compare the performance of the proposed coil with that of a circular coil, a figure-eight coil, and the H-coil. Finally, in addition to its whole-brain stimulation capability (e.g. potentially useful for prophylaxis of epileptic patients) the system is also able to stimulate mainly one brain hemisphere, which may be useful in stroke rehabilitation, among other applications. PMID:25570015

Sousa, Sonia C P; Almeida, Jorge; Cavaleiro Miranda, Pedro; Salvador, Ricardo; Silvestre, Joao; Simoes, Hugo; Crespo, Paulo

2014-08-01

13

Outcomes in spasticity after repetitive transcranial magnetic and transcranial direct current stimulations  

PubMed Central

Non-invasive brain stimulations mainly consist of repetitive transcranial magnetic stimulation and transcranial direct current stimulation. Repetitive transcranial magnetic stimulation exhibits satisfactory outcomes in improving multiple sclerosis, stroke, spinal cord injury and cerebral palsy-induced spasticity. By contrast, transcranial direct current stimulation has only been studied in post-stroke spasticity. To better validate the efficacy of non-invasive brain stimulations in improving the spasticity post-stroke, more prospective cohort studies involving large sample sizes are needed. PMID:25206878

Gunduz, Aysegul; Kumru, Hatice; Pascual-Leone, Alvaro

2014-01-01

14

Transcranial Magnetic Stimulation in Children  

PubMed Central

Developmental disabilities (e.g. attention deficit disorder; cerebral palsy) are frequently associated with deviations of the typical pattern of motor skill maturation. Neurophysiologic tools, such as transcranial magnetic stimulation (TMS), which probe motor cortex function, can potentially provide insights into both typical neuromotor maturation and the mechanisms underlying the motor skill deficits in children with developmental disabilities. These insights may set the stage for finding effective interventions for these disorders. We review the literature pertaining to the use of TMS in pediatrics. Most TMS-evoked parameters show age-related changes in typically developing children and some of these are abnormal in a number of childhood-onset neurological disorders. Although no TMS-evoked parameters are diagnostic for any disorder, changes in certain parameters appear to reflect disease burden or may provide a measure of treatment-related improvement. Furthermore, TMS may be especially useful when combined with other neurophysiologic modalities (e.g. fMRI). However, much work remains to be done to determine if TMS-evoked parameters can be used as valid and reliable biomarkers for disease-burden, the natural history of neurological injury and repair, and the efficacy of pharmacological and rehabilitation interventions. PMID:18221913

Garvey, Marjorie A.; Mall, Volker

2008-01-01

15

Transcranial magnetic stimulation studies of visuospatial attentional control  

E-print Network

Transcranial magnetic stimulation studies of visuospatial attentional control Sara M Szczepanski. Introduction and context Transcranial magnetic stimulation (TMS) is a non-invasive technique that involves is generated, inducing current flow in the brain region directly underneath the coil. The magnetic pulse

Kastner, Sabine

16

[Transcranial magnetic stimulation (TMS) in clinical neurology].  

PubMed

To date, various kinds of transcranial magnetic stimulation (TMS) methods have been widely used in clinical neurology. For the clinical examination, single-pulse TMS is generally used, whereas, for the future therapy, repetitive TMS (rTMS) is widely researched. To evaluate the function of corticospinal tract, central motor conduction time (CMCT) is measured using single-pulse TMS. For precise analyses, single-pulse and double-pulse magnetic brainstem stimulation are performed to measure the cortical-brainstem conduction time and brainstem-spinal conduction time. To evaluate corticospinal tract function for leg muscles, cortico-conus motor conduction time (CCCT) is considered to be more accurate than CMCT. Magnetic cerebellar stimulation is effective to distinguish the cerebellar afferent pathway dysfunction from cerebellar efferent or cerebellar cortical dysfunctions. In animal research, rTMS releases the dopamine in monkey's brain and induces functional changes lasting over one week. In fact, as compared to sham-rTMS, high-frequency rTMS (5Hz) over the supplementary motor area has been shown to be significantly effective in the patients with Parkinson's disease. A new patterned rTMS protocol, quadripulse stimulation (QPS), can produce a bidirectional motor cortical plasticity depending on the interval of the pulses within a burst. rTMS including QPS might relieve symptoms in patients with neurological and psychiatric disorders. PMID:21921446

Matsumoto, Hideyuki; Ugawa, Yoshikazu

2010-11-01

17

Repetitive transcranial magnetic stimulation to SMA worsens complex movements in Parkinson's disease  

E-print Network

the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS) for Parkinson's disease (PD analysis, timed motor performance tests, United Parkinson's Disease Rating Scale (UPDRS), patient self Elsevier Science Ireland Ltd. All rights reserved. Keywords: Parkinson's disease; Transcranial magnetic

Pullman, Seth L.

18

Sham Transcranial Magnetic Stimulation Using Electrical Stimulation of the Scalp  

E-print Network

Sham Transcranial Magnetic Stimulation Using Electrical Stimulation of the Scalp M Mennemeier, PhD1 of electrical stimulation necessary to match 1-Hz rTMS was developed in one sample of normal subjects. The sham of stimulation was active or sham or which was electrical or magnetic. Naïve subjects incorrectly picked sham

Chatterjee, Anjan

19

Handedness, repetitive transcranial magnetic stimulation and bulimic disorders.  

PubMed

Repetitive Transcranial Magnetic Stimulation (rTMS) research in psychiatry mostly excludes left-handed participants. We recruited left-handed people with a bulimic disorder and found that stimulation of the left prefrontal cortex may result in different effects in left- and right-handed people. This highlights the importance of handedness and cortex lateralisation for rTMS. PMID:21067901

Van den Eynde, F; Broadbent, H; Guillaume, S; Claudino, A; Campbell, I C; Schmidt, U

2012-05-01

20

Use of Transcranial Magnetic Stimulation in Autism Spectrum Disorders  

ERIC Educational Resources Information Center

The clinical, social and financial burden of autism spectrum disorder (ASD) is staggering. We urgently need valid and reliable biomarkers for diagnosis and effective treatments targeting the often debilitating symptoms. Transcranial magnetic stimulation (TMS) is beginning to be used by a number of centers worldwide and may represent a novel…

Oberman, Lindsay M.; Rotenberg, Alexander; Pascual-Leone, Alvaro

2015-01-01

21

Functional neuroimaging and repetitive transcranial magnetic stimulation in Parkinson's disease.  

PubMed

Functional neuroimaging provides insights into the pathogenesis of motor symptoms in Parkinson's disease (PD) and improves our understanding of both established neuromodulatory therapies such as deep brain stimulation (DBS) and potential ones such as repetitive transcranial magnetic stimulation (rTMS). Functional imaging studies can reveal the consequences of the dopaminergic lesion in PD among a widespread network of subcortical-cortical regions. Characteristic patterns of normal cortical brain activation for motor tasks are systematically altered in PD. Recent work has emphasized the task dependence of these changes and their gradual evolution over the course of the disease. Clinically relevant PD treatment with medications or DBS tends to normalize these patterns. In this context, rTMS is discussed as a potential noninvasive alternative for neuromodulation of cortical function. Although rTMS is not a current treatment, we review recent rTMS studies in PD that suggest its promise, illustrate how functional imaging can guide application of rTMS, and suggest that subcortical dopamine release could be an rTMS mechanism of action. The combination of rTMS and functional neuroimaging broadens our knowledge of functional cortical networks in PD, which can eventually provide physicians with pathophysiologic information about different PD treatment options and rationales for neuromodulatory interventions. PMID:17514152

Wu, Allan D

2007-01-01

22

Use of transcranial magnetic stimulation to influence behavior  

Microsoft Academic Search

Transcranial magnetic stimulation (TMS) is a noninvasive technique that allows researchers to induce electrical currents in\\u000a focal areas of the cerebral cortex. These currents can transiently activate or inhibit focal cortical areas and thus influence\\u000a behavior. In the 20 years since its introduction, TMS has been applied to the study and treatment of a wide variety of neurologic\\u000a and psychiatric

Benzi M. Kluger; William J. Triggs

2007-01-01

23

Comparison of descending volleys evoked by transcranial magnetic and electric stimulation in conscious humans  

Microsoft Academic Search

Objectives: The present experiments were designed to compare the understanding of the transcranial electric and magnetic stimulation of the human motorcortex.Methods: The spinal volleys evoked by single transcranial magnetic or electric stimulation over the cerebral motor cortex were recorded from a bipolar electrode inserted into the cervical epidural space of two conscious human subjects. These volleys were termed D- and

V Di Lazzaro; A Oliviero; P Profice; E Saturno; F Pilato; A Insola; P Mazzone; P Tonali; J. C Rothwell

1998-01-01

24

[Repetitive transcranial magnetic stimulation and rehabilitation].  

PubMed

NEURO (NovEl intervention Using Repetitive TMS and intensive Occupational therapy) have been recently reported to be clinically beneficial for post-stroke patients with upper limb hemiparesis. We confirmed the safety and feasibility of the protocol in 1,008 post-stroke patients from different institutions, and identify predictors of the clinical response to the treatment. And in our randomized controlled study of NEURO and constraint-induced movement therapy, NEURO showed the superiority of NEURO relative to constraint-induced movement therapy; NEURO improved the motion of the whole upper limb and resulted. We have investigated the recovery mechanism using electrophysiological examination and functional magnetic resonance imaging. Low-frequency rTMS applied to the non-lesional hemisphere in post-stroke patients significantly decreased the F-wave frequency and amplitude in the affected upper limb, suggesting that this modality has an anti-spastic effect in post-stroke patients. Serial functional magnetic resonance imaging indicated that our proposed treatment can induce functional cortical reorganization, leading to motor functional recovery of the affected upper limb. Especially, it seems that neural activation in the lesional hemisphere plays an important role in such recovery in poststroke hemiparetic patients. PMID:24291951

Abo, Masahiro

2013-01-01

25

Transcranial Magnetic Stimulation in Child Neurology: Current and Future Directions  

PubMed Central

Transcranial magnetic stimulation (TMS) is a method for focal brain stimulation based on the principle of electromagnetic induction, where small intracranial electric currents are generated by a powerful, rapidly changing extracranial magnetic field. Over the past 2 decades TMS has shown promise in the diagnosis, monitoring, and treatment of neurological and psychiatric disease in adults, but has been used on a more limited basis in children. We reviewed the literature to identify potential diagnostic and therapeutic applications of TMS in child neurology and also its safety in pediatrics. Although TMS has not been associated with any serious side effects in children and appears to be well tolerated, general safety guidelines should be established. The potential for applications of TMS in child neurology and psychiatry is significant. Given its excellent safety profile and possible therapeutic effect, this technique should develop as an important tool in pediatric neurology over the next decade. PMID:18056688

Frye, Richard E.; Rotenberg, Alexander; Ousley, Molliann; Pascual-Leone, Alvaro

2008-01-01

26

Repetitive transcranial magnetic stimulation in anorexia nervosa: a pilot study.  

PubMed

The search for new treatments to improve outcome in people with anorexia nervosa continues. This pilot study investigated whether one session of high frequency repetitive transcranial magnetic stimulation (rTMS) delivered to the left dorsolateral prefrontal cortex reduces eating disorder related symptoms following exposure to visual and real food stimuli. Safety and tolerability were also assessed. Ten right-handed people with anorexia nervosa underwent one session of rTMS. Subjective experiences related to the eating disorder (e.g. urge to restrict, feeling full etc.) were assessed before and after rTMS. Non-parametric repeated measures tests were used. rTMS was safe and well-tolerated, and resulted in reduced levels of feeling full, feeling fat and feeling anxious. Thus, rTMS may reduce core symptoms of anorexia nervosa. Future research should establish the therapeutic potential of rTMS in anorexia nervosa. PMID:21880470

Van den Eynde, F; Guillaume, S; Broadbent, H; Campbell, I C; Schmidt, U

2013-02-01

27

Use of transcranial magnetic stimulation in autism spectrum disorders.  

PubMed

The clinical, social and financial burden of autism spectrum disorder (ASD) is staggering. We urgently need valid and reliable biomarkers for diagnosis and effective treatments targeting the often debilitating symptoms. Transcranial magnetic stimulation (TMS) is beginning to be used by a number of centers worldwide and may represent a novel technique with both diagnostic and therapeutic potential. Here we critically review the current scientific evidence for the use of TMS in ASD. Though preliminary data suggests promise, there is simply not enough evidence yet to conclusively support the clinical widespread use of TMS in ASD, neither diagnostically nor therapeutically. Carefully designed and properly controlled clinical trials are warranted to evaluate the true potential of TMS in ASD. PMID:24127165

Oberman, Lindsay M; Rotenberg, Alexander; Pascual-Leone, Alvaro

2015-02-01

28

Effect of transcranial magnetic stimulation on force of finger pinch  

NASA Astrophysics Data System (ADS)

Transcranial magnetic stimulation (TMS) is used to explore many aspects of brain function, and to treat neurological disorders. Cortical motor neuronal activation by TMS over the primary motor cortex (M1) produces efferent signals that pass through the corticospinal tracts. Motor-evoked potentials (MEPs) are observed in muscles innervated by the stimulated motor cortex. TMS can cause a silent period (SP) following MEP in voluntary electromyography (EMG). The present study examined the effects of TMS eliciting MEP and SP on the force of pinching using two fingers. Subjects pinched a wooden block with the thumb and index finger. TMS was applied to M1 during the pinch task. EMG of first dorsal interosseous muscles and pinch forces were measured. Force output increased after the TMS, and then oscillated. The results indicated that the motor control system to keep isotonic forces of the muscles participated in the finger pinch was disrupted by the TMS.

Odagaki, Masato; Fukuda, Hiroshi; Hiwaki, Osamu

2009-04-01

29

Effect of Prefrontal Repetitive Transcranial Magnetic Stimulation in Obsessive-Compulsive Disorder: A Preliminary Study  

Microsoft Academic Search

Objective: Prefrontal mechanisms are implicated in obsessive-compulsive disorder. The authors investigated whether prefrontal repetitive transcranial magnetic stimulation influenced obsessive-compulsive disorder symptoms. Method: Twelve patients with obsessive-compulsive disorder were given repetitive transcranial magnetic stimulation (80% motor threshold, 20 Hz\\/2 seconds per minute for 20 minutes) to a right lateral prefrontal, a left lateral prefrontal, and a midoccipital (control) site on separate

Benjamin D. Greenberg; Mark S. George; Juliet D. Martin; Jonathan Benjamin; Thomas E. Schlaepfer; Margaret Altemus; Eric M. Wassermann; Robert M. Post; Dennis L. Murphy

1997-01-01

30

Medical devices; neurological devices; classification of the transcranial magnetic stimulator for headache. Final order.  

PubMed

The Food and Drug Administration (FDA) is classifying the transcranial magnetic stimulator for headache into class II (special controls). The special controls that will apply to the device are identified in this order, and will be part of the codified language for the transcranial magnetic stimulator for headache classification. The Agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. PMID:25016622

2014-07-01

31

Transcranial magnetic stimulation in schizophrenia: the contribution of neuroimaging.  

PubMed

At the most basic level, the Transcranial Magnetic Stimulation(TMS) is a neuro-scientific tool that exerts its action by influencing the neo-cortical functions. However, in-spite of so many well-evidenced roles of TMS in neuropsychiatric conditions, its exact mechanism of action remains to be known. More intriguing are its therapeutic effects in Schizophrenia at the Cerebral-level. In this review, we adopt a neuro-imaging approach for this exploration. We review the present literature for the studies in Schizophrenia which have used a combination of rTMS with 1) Electroenchephalogram (EEG) 2)The functional Magnetic Resonance Imaging (fMRI) and the 3) Positron Emission Tomography (PET)/ Single-Photon Emission Computed Tomography. The TMS-EEG combination provides direct effects of TMS on the electro- magnetic field (EMF) of brain. The TMS-fMRI/PET/SPECT combinations are very effective in exploring the functional connectivity in brains of Schizophrenia patients as well as in performing rTMS guided neuro-navigation. Our review suggests that TMS combined with other neuroimaging modalities are needed for a better clarification of its neural actions. PMID:23409741

Du, Zhong-de; Wang, R; Prakash, Ravi; Chaudhury, S; Dayananda, G

2012-01-01

32

Repetitive Transcranial Magnetic Stimulation Activates Specific Regions in Rat Brain  

NASA Astrophysics Data System (ADS)

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique to induce electric currents in the brain. Although rTMS is being evaluated as a possible alternative to electroconvulsive therapy for the treatment of refractory depression, little is known about the pattern of activation induced in the brain by rTMS. We have compared immediate early gene expression in rat brain after rTMS and electroconvulsive stimulation, a well-established animal model for electroconvulsive therapy. Our result shows that rTMS applied in conditions effective in animal models of depression induces different patterns of immediate-early gene expression than does electroconvulsive stimulation. In particular, rTMS evokes strong neural responses in the paraventricular nucleus of the thalamus (PVT) and in other regions involved in the regulation of circadian rhythms. The response in PVT is independent of the orientation of the stimulation probe relative to the head. Part of this response is likely because of direct activation, as repetitive magnetic stimulation also activates PVT neurons in brain slices.

Ji, Ru-Rong; Schlaepfer, Thomas E.; Aizenman, Carlos D.; Epstein, Charles M.; Qiu, Dike; Huang, Justin C.; Rupp, Fabio

1998-12-01

33

Modulating functional and dysfunctional mentalizing by transcranial magnetic stimulation  

PubMed Central

Mentalizing, the ability to attribute mental states to others and oneself, is a cognitive function with high relevance for social interactions. Recent neuroscientific research has increasingly contributed to attempts to decompose this complex social cognitive function into constituting neurocognitive building blocks. Additionally, clinical research that focuses on social cognition to find links between impaired social functioning and neurophysiological deviations has accumulated evidence that mentalizing is affected in most psychiatric disorders. Recently, both lines of research have started to employ transcranial magnetic stimulation: the first to modulate mentalizing in order to specify its neurocognitive components, the latter to treat impaired mentalizing in clinical conditions. This review integrates findings of these two different approaches to draw a more detailed picture of the neurocognitive basis of mentalizing and its deviations in psychiatric disorders. Moreover, we evaluate the effectiveness of hitherto employed stimulation techniques and protocols, paradigms and outcome measures. Based on this overview we highlight new directions for future research on the neurocognitive basis of functional and dysfunctional social cognition. PMID:25477838

Schuwerk, Tobias; Langguth, Berthold; Sommer, Monika

2014-01-01

34

Physiology of repetitive transcranial magnetic stimulation of the human brain.  

PubMed

During the last two decades, transcranial magnetic stimulation (TMS) has rapidly become a valuable method to investigate noninvasively the human brain. In addition, repetitive TMS (rTMS) is able to induce changes in brain activity that last after stimulation. Therefore, rTMS has therapeutic potential in patients with neurologic and psychiatric disorders. It is, however, unclear by which mechanism rTMS induces these lasting effects on the brain. The effects of rTMS are often described as LTD- or LTP-like, because the duration of these alterations seems to implicate changes in synaptic plasticity. In this review we therefore discuss, based on rTMS experiments and knowledge about synaptic plasticity, whether the physiologic basis of rTMS-effects relates to changes in synaptic plasticity. We present seven lines of evidence that strongly suggest a link between the aftereffects induced by rTMS and the induction of synaptic plasticity. It is, nevertheless, important to realize that at present it is impossible to demonstrate a direct link between rTMS on the one hand and synaptic plasticity on the other. Therefore, we provide suggestions for future, innovating research, aiming to investigate both the local effects of rTMS on the synapse and the effects of rTMS on other, more global levels of brain organization. Only in that way can the aftereffects of rTMS on the brain be completely understood. PMID:20633438

Hoogendam, Janna Marie; Ramakers, Geert M J; Di Lazzaro, Vincenzo

2010-04-01

35

Repetitive transcranial magnetic stimulation for major depressive disorder: a review.  

PubMed

Several studies demonstrated that repetitive transcranial magnetic stimulation (rTMS) is an efficacious treatment for treatment-resistant major depressive disorder (TRD). Recent metaanalyses and more recent large multicentre studies provided evidence suggesting that rTMS is indeed a promising treatment; however, its efficacy has often been shown to be modest, compared with sham stimulation. We review these lines of evidence and discuss several reasons that may explain the modest therapeutic efficacy in most of these studies, including: most involved left-sided treatment alone to the dorsolateral prefrontal cortex (DLPFC) only, which may be less optimal than applying bilateral stimulation; suboptimal methods were used to target the DLPFC (that is, the 5-cm anterior method), limiting the treatment potential of inherently a targeted form of treatment; some treatment durations were short (that is, 2 to 4 weeks); and stimulation intensity might have been insufficient by not considering coil-to-cortex distance, which has been linked to rTMS-induced antidepressant response. Future studies attempting to address the above-mentioned limitations are necessary to potentially optimize the efficacy of this already promising treatment option in TRD. Finally, it is also essential that research investigate the mechanisms of therapeutic efficacy, thus increases in understanding can be translated into enhanced treatment. For several reasons that will be reviewed, cortical excitability may represent an important mechanism, linked to the therapeutic efficacy of this disorder. PMID:18801218

Daskalakis, Z Jeff; Levinson, Andrea J; Fitzgerald, Paul B

2008-09-01

36

Effect of Transcranial Magnetic Stimulation on Neuronal Networks  

NASA Astrophysics Data System (ADS)

The human brain contains around 100 billion nerve cells controlling our day to day activities. Consequently, brain disorders often result in impairments such as paralysis, loss of coordination and seizure. It has been said that 1 in 5 Americans suffer some diagnosable mental disorder. There is an urgent need to understand the disorders, prevent them and if possible, develop permanent cure for them. As a result, a significant amount of research activities is being directed towards brain research. Transcranial Magnetic Stimulation (TMS) is a promising tool for diagnosing and treating brain disorders. It is a non-invasive treatment method that produces a current flow in the brain which excites the neurons. Even though TMS has been verified to have advantageous effects on various brain related disorders, there have not been enough studies on the impact of TMS on cells. In this study, we are investigating the electrophysiological effects of TMS on one dimensional neuronal culture grown in a circular pathway. Electrical currents are produced on the neuronal networks depending on the directionality of the applied field. This aids in understanding how neuronal networks react under TMS treatment.

Unsal, Ahmet; Hadimani, Ravi; Jiles, David

2013-03-01

37

Transcranial magnetic stimulation and amyotrophic lateral sclerosis: pathophysiological insights  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the motor neurons in the motor cortex, brainstem and spinal cord. A combination of upper and lower motor neuron dysfunction comprises the clinical ALS phenotype. Although the ALS phenotype was first observed by Charcot over 100?years ago, the site of ALS onset and the pathophysiological mechanisms underlying the development of motor neuron degeneration remain to be elucidated. Transcranial magnetic stimulation (TMS) enables non-invasive assessment of the functional integrity of the motor cortex and its corticomotoneuronal projections. To date, TMS studies have established motor cortical and corticospinal dysfunction in ALS, with cortical hyperexcitability being an early feature in sporadic forms of ALS and preceding the clinical onset of familial ALS. Taken together, a central origin of ALS is supported by TMS studies, with an anterograde transsynaptic mechanism implicated in ALS pathogenesis. Of further relevance, TMS techniques reliably distinguish ALS from mimic disorders, despite a compatible peripheral disease burden, thereby suggesting a potential diagnostic utility of TMS in ALS. This review will focus on the mechanisms underlying the generation of TMS measures used in assessment of cortical excitability, the contribution of TMS in enhancing the understanding of ALS pathophysiology and the potential diagnostic utility of TMS techniques in ALS. PMID:23264687

Vucic, Steve; Ziemann, Ulf; Eisen, Andrew; Hallett, Mark; Kiernan, Matthew C

2013-01-01

38

Transcranial magnetic stimulation in the treatment of substance addiction.  

PubMed

Transcranial magnetic stimulation (TMS) is a noninvasive method of brain stimulation used to treat a variety of neuropsychiatric disorders, but is still in the early stages of study as addiction treatment. We identified 19 human studies using repetitive TMS (rTMS) to manipulate drug craving or use, which exposed a total of 316 adults to active rTMS. Nine studies involved tobacco, six alcohol, three cocaine, and one methamphetamine. The majority of studies targeted high-frequency (5-20 Hz; expected to stimulate neuronal activity) rTMS pulses to the dorsolateral prefrontal cortex. Only five studies were controlled clinical trials: two of four nicotine trials found decreased cigarette smoking; the cocaine trial found decreased cocaine use. Many aspects of optimal treatment remain unknown, including rTMS parameters, duration of treatment, relationship to cue-induced craving, and concomitant treatment. The mechanisms of rTMS potential therapeutic action in treating addictions are poorly understood, but may involve increased dopamine and glutamate function in corticomesolimbic brain circuits and modulation of neural activity in brain circuits that mediate cognitive processes relevant to addiction, such as response inhibition, selective attention, and reactivity to drug-associated cues. rTMS treatment of addiction must be considered experimental at this time, but appears to have a promising future. PMID:25069523

Gorelick, David A; Zangen, Abraham; George, Mark S

2014-10-01

39

Modeling the effects of transcranial magnetic stimulation on cortical circuits.  

PubMed

Transcranial magnetic stimulation (TMS) is commonly used to activate or inactivate specific cortical areas in a noninvasive manner. Because of technical constraints, the precise effects of TMS on cortical circuits are difficult to assess experimentally. Here, this issue is investigated by constructing a detailed model of a portion of the thalamocortical system and examining the effects of the simulated delivery of a TMS pulse. The model, which incorporates a large number of physiological and anatomical constraints, includes 33,000 spiking neurons arranged in a 3-layered motor cortex and over 5 million intra- and interlayer synaptic connections. The model was validated by reproducing several results from the experimental literature. These include the frequency, timing, dose response, and pharmacological modulation of epidurally recorded responses to TMS (the so-called I-waves), as well as paired-pulse response curves consistent with data from several experimental studies. The modeled responses to simulated TMS pulses in different experimental paradigms provide a detailed, self-consistent account of the neural and synaptic activities evoked by TMS within prototypical cortical circuits. PMID:15788519

Esser, Steve K; Hill, Sean L; Tononi, Giulio

2005-07-01

40

Low-frequency repetitive transcranial magnetic simulation prevents chronic epileptic seizure.  

PubMed

Although low-frequency repetitive transcranial magnetic simulation can potentially treat epilepsy, its underlying mechanism remains unclear. This study investigated the influence of low-frequency re-petitive transcranial magnetic simulation on changes in several nonlinear dynamic electroence-phalographic parameters in rats with chronic epilepsy and explored the mechanism underlying petitive transcranial magnetic simulation-induced antiepileptic effects. An epilepsy model was es-tablished using lithium-pilocarpine intraperitoneal injection into adult Sprague-Dawley rats, which were then treated with repetitive transcranial magnetic simulation for 7 consecutive days. Nonlinear electroencephalographic parameters were obtained from the rats at 7, 14, and 28 days post-stimulation. Results showed significantly lower mean correlation-dimension and Kolmogo-rov-entropy values for stimulated rats than for non-stimulated rats. At 28 days, the complexity and point-wise correlation dimensional values were lower in stimulated rats. Low-frequency repetitive transcranial magnetic simulation has suppressive effects on electrical activity in epileptic rats, thus explaining its effectiveness in treating epilepsy. PMID:25206567

Wang, Yinxu; Wang, Xiaoming; Ke, Sha; Tan, Juan; Hu, Litian; Zhang, Yaodan; Cui, Wenjuan

2013-09-25

41

3-dimensional modeling of transcranial magnetic stimulation: Design and application  

NASA Astrophysics Data System (ADS)

Over the past three decades, transcranial magnetic stimulation (TMS) has emerged as an effective tool for many research, diagnostic and therapeutic applications in humans. TMS delivers highly localized brain stimulations via non-invasive externally applied magnetic fields. This non-invasive, painless technique provides researchers and clinicians a unique tool capable of stimulating both the central and peripheral nervous systems. However, a complete analysis of the macroscopic electric fields produced by TMS has not yet been performed. In this dissertation, we present a thorough examination of the total electric field induced by TMS in air and a realistic head model with clinically relevant coil poses. In the first chapter, a detailed account of TMS coil wiring geometry was shown to provide significant improvements in the accuracy of primary E-field calculations. Three-dimensional models which accounted for the TMS coil's wire width, height, shape and number of turns clearly improved the fit of calculated-to-measured E-fields near the coil body. Detailed primary E-field models were accurate up to the surface of the coil body (within 0.5% of measured values) whereas simple models were often inadequate (up to 32% different from measured). In the second chapter, we addressed the importance of the secondary E-field created by surface charge accumulation during TMS using the boundary element method (BEM). 3-D models were developed using simple head geometries in order to test the model and compare it with measured values. The effects of tissue geometry, size and conductivity were also investigated. Finally, a realistic head model was used to assess the effect of multiple surfaces on the total E-field. We found that secondary E-fields have the greatest impact at areas in close proximity to each tissue layer. Throughout the head, the secondary E-field magnitudes were predominantly between 25% and 45% of the primary E-fields magnitude. The direction of the secondary E-field was primarily in opposition to the primary E-field, however there are some locations (i.e. going from high to low conductivity) where the secondary E-field adds to the primary E-field. Thus the total E-field vector may change in magnitude and direction. These findings show that realistic head geometries should be used when modeling the total E-field. In the third chapter, we addressed the importance of the secondary electric field (E-field) in a realistic head model using the boundary element method at clinically relevant coil positions and orientations (ex. primary motor cortex) during transcranial magnetic stimulation (TMS). The effective E-fields produced at each clinical orientation were then correlated with electromyographic (EMG) recordings using the total E-field with the cortical column cosine model. Some TMS coil orientations led to total E-fields as much as 40% lower than the primary E-fields at sites located on the TMS coil's main axis of stimulation. Effective E-field values at the cortical level, were highly correlated (r = 0.9644, P < 0.01) with EMG responses indicating that both local biological characteristics (such as tissue geometry and electrical conductivity) and the total E-field induced by the TMS coil may provide a means for predicting the optimum coil position/orientation to consistently produce neuronal activations.

Salinas, Felipe Santiago

42

Transcranial magnetic stimulation in cognitive neuroscience – virtual lesion, chronometry, and functional connectivity  

Microsoft Academic Search

Fifteen years after its introduction by Anthony Barker, transcranial magnetic stimulation (TMS) appears to be ‘coming of age’ in cognitive neuroscience and promises to reshape the way we investigate brain–behavior relations. Among the many methods now available for imaging the activity of the human brain, magnetic stimulation is the only technique that allows us to interfere actively with brain function.

Alvaro Pascual-Leone; Vincent Walsh; John Rothwell

2000-01-01

43

ESTIMULACIÓN MAGNETICA TRANSCRANEAL: APLICACIONES EN NEUROCIENCIA COGNITIVA TRANSCRANIAL MAGNETIC STIMULATION: AN APPROACH FROM COGNITIVE NEUROSCIENCE  

Microsoft Academic Search

Objective: In this review we trace some of the mayor developments in the use of Transcranial magnetic stimulation (TMS) as a technique for the investigation of cognitive neuroscience and its application as an assessment and rehabilitation tool in some psychiatric and neurological disorders. Technical aspects and safety studies in animal and humans of the magnetic stimulation are also reviewed. Development:

Beatriz Calvo Merino; Patrick Haggard

44

Analysis of the effect of repeated-pulse transcranial magnetic stimulation at the Guangming point on electroencephalograms  

PubMed Central

Here, we administered repeated-pulse transcranial magnetic stimulation to healthy people at the left Guangming (GB37) and a mock point, and calculated the sample entropy of electroencephalo-gram signals using nonlinear dynamics. Additionally, we compared electroencephalogram sample entropy of signals in response to visual stimulation before, during, and after repeated-pulse tran-scranial magnetic stimulation at the Guangming. Results showed that electroencephalogram sample entropy at left (F3) and right (FP2) frontal electrodes were significantly different depending on where the magnetic stimulation was administered. Additionally, compared with the mock point, electroencephalogram sample entropy was higher after stimulating the Guangming point. When visual stimulation at Guangming was given before repeated-pulse transcranial magnetic stimula-tion, significant differences in sample entropy were found at five electrodes (C3, Cz, C4, P3, T8) in parietal cortex, the central gyrus, and the right temporal region compared with when it was given after repeated-pulse transcranial magnetic stimulation, indicating that repeated-pulse transcranial magnetic stimulation at Guangming can affect visual function. Analysis of electroencephalogram revealed that when visual stimulation preceded repeated pulse transcranial magnetic stimulation, sample entropy values were higher at the C3, C4, and P3 electrodes and lower at the Cz and T8 electrodes than visual stimulation followed preceded repeated pulse transcranial magnetic stimula-tion. The findings indicate that repeated-pulse transcranial magnetic stimulation at the Guangming evokes different patterns of electroencephalogram signals than repeated-pulse transcranial mag-netic stimulation at other nearby points on the body surface, and that repeated-pulse transcranial magnetic stimulation at the Guangming is associated with changes in the complexity of visually evoked electroencephalogram signals in parietal regions, central gyrus, and temporal regions. PMID:25206853

Zhang, Xin; Fu, Lingdi; Geng, Yuehua; Zhai, Xiang; Liu, Yanhua

2014-01-01

45

Repetitive transcranial magnetic stimulation for Mal de Debarquement Syndrome  

PubMed Central

Objective Mal de debarquement syndrome (MdDS) is a chronic disorder of imbalance characterized by a feeling of rocking and swaying. The disorder starts after prolonged exposure to passive motion such as from a boat or plane. All medical treatment is palliative and symptoms that persist beyond six months show low likelihood of remission. This pilot study explored the feasibility and tolerability of repetitive transcranial magnetic stimulation (rTMS) as potential treatment for MdDS. Patients/Intervention Ten subjects (8 women) with persistent MdDS lasting from 10 to 91 months were given one session each of four counterbalanced protocols: left 10Hz (high frequency), left 1Hz (low frequency), right 10Hz, and right 1Hz rTMS over the dorsolateral prefrontal cortex (DLPFC). Main Outcome Measure Reduction of rocking sensation reported on a visual analogue scale. Results 1) Right-handers improved most with 10Hz stimulation over the left DLPFC while left-handers improved most with 10Hz stimulation over the right DLPFC; 2) Low frequency DLPFC stimulation was associated with symptom worsening in some subjects; 3) Duration of symptoms was negatively correlated with treatment response; 4) rTMS was well-tolerated in MdDS subjects, showing similar rates of headache (10 of 40 sessions) as for other studies; 5) Fatigue occurred after six sessions usually with low frequency stimulation. Conclusion rTMS was well-tolerated in subjects with MdDS with promising short-term symptom improvement. Future studies of rTMS in MdDS may consider sequential days of stimulation, longer post-rTMS observation periods, formal measurement of post-TMS fatigue, and randomization with a sham condition. PMID:23202153

Cha, Yoon-Hee; Cui, Yongyan; Baloh, Robert W.

2012-01-01

46

[Therapeutic application of repetitive transcranial magnetic stimulation for major depression].  

PubMed

It has been reported that approximately one third of patients with major depression are medication-resistant. In spite of partial responsiveness to antidepressants, most of the medication-resistant patients remain incompletely remitted without successful social reintegration. Symptom severity could be mild to moderate for many of them due to the incomplete remission, and, thus, electroconvulsive therapy is not applicable for them. However, they usually feel some difficulty performing cognitive behavioral therapy or social rehabilitation training due to residual symptoms such as thought inhibition and hypobulia. Under such conditions, those patients are longing for treatment options complementary to antidepressants, for less painful social reintegration. In October 2008, the Food and Drug Administration (FDA) of the United States finally approved repetitive Transcranial Magnetic Stimulation (rTMS) for medication-resistant patients with major depression. The main reason for the FDA approval was that rTMS had shown similar effectiveness (effect size around 0.39 in a recent meta-analysis) to antidepressants for medication-resistant patients without serious adverse effects. TMS is a brain stimulation methodology employing magnetic energy which can penetrate the skull bone without energy decay, and, thus, eddy currents induced by TMS can stimulate cerebral cortices effectively and locally. When TMS is repetitively delivered over several hundreds of pulses within a session, stimulation effects can be observed beyond the stimulation period as aftereffects. Moreover, when a daily rTMS session is repeated over several weeks, rTMS could have antidepressant effects. Clinical trials of rTMS for depression have employed two kinds of rTMS protocol of high-frequency (facilitatory) rTMS over the left Dorsolateral Prefrontal Cortex (DLPFC) and low-frequency (inhibitory) rTMS over the right DLPFC. Although the antidepressant action of rTMS over DLPFC has not been fully elucidated, the neuronal level hypothesis includes the induction of neuroplasticity and activation of the dopamine system, and the neuronal circuitry level hypothesis includes the activation of the left DLPFC and inhibition of the right DLPFC and (para) limbic system such as the subgenual cingulate cortex and amygdala. On the therapeutic application of rTMS in clinical psychiatry, neuroethics and low invasiveness should be fully considered along with a negative history of punitive electroconvulsive therapy and prefrontal lobotomy. It is important to investigate the neurobiological mechanism of rTMS treatment and to place rTMS in a suitable position within comprehensive treatment algorithms of major depression. PMID:23367835

Nakamura, Motoaki

2012-01-01

47

Spatial neglect in near and far space investigated by repetitive transcranial magnetic stimulation  

Microsoft Academic Search

Summary Localized repetitive transcranial magnetic stimulation was used to disrupt visuospatial perception in the near and far space of six healthy volunteer subjects. In addi- tion to the baseline condition, they were stimulated over the right posterior parietal cortex, the right or left dorsal occipital cortex or the right ventral occipital cortex, during the brief presentation of a transected horizontal

Otto Bjoertomt; Alan Cowey; Vincent Walsh

2002-01-01

48

A new method for reproducible coil positioning in transcranial magnetic stimulation mapping  

Microsoft Academic Search

A new method is presented for mapping the motor cortex by transcranial magnetic stimulation in which the position of the stimulation coil on the scalp is measured using a 3D digitizer. The reproducibility of the method was tested by mapping 3 times the left abductor digiti minimi of 6 right-handed subjects and calculating the position of the centre of gravity

Pedro Cavaleiro Miranda; Mamede de Carvalho; Isabel Conceição; M. L. Sales Luis; Eduardo Ducla-Soares

1997-01-01

49

MRI-free neuronavigation for transcranial magnetic stimulation in severe depression  

E-print Network

MRI-free neuronavigation for transcranial magnetic stimulation in severe depression Beno^it Comb that this neuronavigation method is reproducible and acceptable for routine application of rTMS in severe depression. 1 neuronavigation without MRI in the context of rTMS for severe, drug-resistant depression. It is generally admitted

Paris-Sud XI, Université de

50

Low and High Frequency Repetitive Transcranial Magnetic Stimulation for the Treatment of Spasticity  

ERIC Educational Resources Information Center

The development of non-invasive techniques of cortical stimulation, such as transcranial magnetic stimulation (TMS), has opened new potential avenues for the treatment of neuropsychiatric diseases. We hypothesized that an increase in the activity in the motor cortex by cortical stimulation would increase its inhibitory influence on spinal…

Valle, Angela C.; Dionisio, Karen; Pitskel, Naomi Bass; Pascual-Leone, Alvaro; Orsati, Fernanda; Ferreira, Merari J. L.; Boggio, Paulo S.; Lima, Moises C.; Rigonatti, Sergio P.; Fregni, Felipe

2007-01-01

51

Functional neuroimaging of the baboon during concurrent image-guided transcranial magnetic stimulation  

E-print Network

Functional neuroimaging of the baboon during concurrent image-guided transcranial magnetic different TMS variables, therefore we developed a baboon model to facilitate testing of some of the current healthy, adult baboons. Published by Elsevier Inc. Introduction Over the past three decades, researchers

Duong, Timothy Q.

52

Functional Connectivity of Human Premotor and Motor Cortex Explored with Repetitive Transcranial Magnetic Stimulation  

Microsoft Academic Search

Connections between the premotor cortex and the primary motor cortex are dense and are important in the visual guidance of arm movements. We have shown previously that it is possi- ble to engage these connections in humans and to measure the net amount of inhibition\\/facilitation from premotor to motor cortex using single-pulse transcranial magnetic stimulation (TMS). The aim of this

A. Munchau; B. R. Bloem; K. Irlbacher; M. R. Trimble; J. C. Rothwell

2002-01-01

53

Transcranial magnetic stimulation and the motor learning-associated cortical plasticity  

Microsoft Academic Search

It has been well established that repetitive motor performance and skill learning alter the functional organization of human corticomotoneuronal system. Over the past decade, transcranial magnetic stimulation (TMS) has helped to demonstrate motor practice and learning-related changes in corticomotoneuronal excitability and representational plasticity. It has also provided some insights into the mechanisms underlying such plasticity. TMS-derived indices show that motor

Milos Ljubisavljevic

2006-01-01

54

Transcranial magnetic stimulation in the visual system. II. Characterization of induced phosphenes and scotomas  

Microsoft Academic Search

Transcranial magnetic stimulation (TMS) induces phosphenes and disrupts visual perception when applied over the occipital pole. Both the underlying mechanisms and the brain structures involved are still unclear. In the first part of this study we show that the masking effect of TMS differs to masking by light in terms of the psychometric function. Here we investigate the emergence of

Thomas Kammer; Klaas Puls; Michael Erb; Wolfgang Grodd

2005-01-01

55

The Role of the Dorsolateral Prefrontal Cortex in Bimodal Divided Attention: Two Transcranial Magnetic Stimulation Studies  

Microsoft Academic Search

The neural processes underlying the ability to divide attention between multiple sensory modalities remain poorly understood. To investigate the role of the dorsolateral prefrontal cortex (DLPFC) in bimodal divided attention, we completed two repetitive transcranial magnetic stimulation (rTMS) studies. We tested the hypothesis that the DLPFC is necessary in the ability to divide attention across modalities. This hypothesis originated as

Jennifer Adrienne Johnson; Antonio P. Strafella; Robert J. Zatorre

2007-01-01

56

Release of premotor activity after repetitive transcranial magnetic stimulation of prefrontal cortex  

Microsoft Academic Search

In the present study we aimed to explore by means of repetitive transcranial magnetic stimulation (rTMS) the reciprocal influences between prefrontal cortex (PFC) and premotor cortex (PMC). Subjects were asked to observe on a computer monitor different pictures representing manipulations of different kind of tools. They had to produce a movement (go condition) or to keep the resting position (no-go

Massimo Gangitano; Felix M. Mottaghy; Alvaro Pascual-Leone

2008-01-01

57

Transcranial magnetic stimulation (TMS) in controlled treatment studies: are some “sham” forms active?  

Microsoft Academic Search

Background: Carefully designed controlled studies are essential in further evaluating the therapeutic efficacy of transcranial magnetic stimulation (TMS) in psychiatric disorders. A major methodological concern is the design of the “sham” control for TMS. An ideal sham would produce negligible cortical stimulation in conjunction with a scalp sensation akin to real treatment. Strategies employed so far include alterations in the

Colleen K. Loo; Janet L. Taylor; Simon C. Gandevia; Benjamin N. McDarmont; Philip B. Mitchell; Perminder S. Sachdev

2000-01-01

58

Noninvasive techniques for probing neurocircuitry and treating illness: vagus nerve stimulation (VNS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS)  

Microsoft Academic Search

Although the preceding chapters discuss much of the new knowledge of neurocircuitry of neuropsychiatric diseases, and an invasive approach to treatment, this chapter describes and reviews the noninvasive methods of testing circuit-based theories and treating neuropsychiatric diseases that do not involve implanting electrodes into the brain or on its surface. These techniques are transcranial magnetic stimulation, vagus nerve stimulation, and

Mark S George; Gary Aston-Jones

2010-01-01

59

Transcranial magnetic stimulation and transcranial direct current stimulation: treatments for cognitive and neuropsychiatric symptoms in the neurodegenerative dementias?  

PubMed Central

Introduction Two methods of non-invasive brain stimulation, transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have demonstrable positive effects on cognition and can ameliorate neuropsychiatric symptoms such as depression. Less is known about the efficacy of these approaches in common neurodegenerative diseases. In this review, we evaluate the effects of TMS and tDCS upon cognitive and neuropsychiatric symptoms in the major dementias, including Alzheimer’s disease (AD), vascular dementia (VaD), dementia with Lewy bodies (DLB), Parkinson’s disease with dementia (PDD), and frontotemporal dementia (FTD), as well as the potential pre-dementia states of Mild Cognitive Impairment (MCI) and Parkinson’s disease (PD). Methods PubMed (until 7 February 2014) and PsycINFO (from 1967 to January Week 3 2014) databases were searched in a semi-systematic manner in order to identify relevant treatment studies. A total of 762 studies were identified and 32 studies (18 in the dementias and 14 in PD populations) were included. Results No studies were identified in patients with PDD, FTD or VaD. Of the dementias, 13 studies were conducted in patients with AD, one in DLB, and four in MCI. A total of 16 of the 18 studies showed improvements in at least one cognitive or neuropsychiatric outcome measure. Cognitive or neuropsychiatric improvements were observed in 12 of the 14 studies conducted in patients with PD. Conclusions Both TMS and tDCS may have potential as interventions for the treatment of symptoms associated with dementia and PD. These results are promising; however, available data were limited, particularly within VaD, PDD and FTD, and major challenges exist in order to maximise the efficacy and clinical utility of both techniques. In particular, stimulation parameters vary considerably between studies and are likely to subsequently impact upon treatment efficacy. PMID:25478032

2014-01-01

60

Pressure Pain Thresholds Increase after Preconditioning 1 Hz Repetitive Transcranial Magnetic Stimulation with Transcranial Direct Current Stimulation  

PubMed Central

Background The primary motor cortex (M1) is an effective target of non-invasive cortical stimulation (NICS) for pain threshold modulation. It has been suggested that the initial level of cortical excitability of M1 plays a key role in the plastic effects of NICS. Objective Here we investigate whether transcranial direct current stimulation (tDCS) primed 1 Hz repetitive transcranial magnetic stimulation (rTMS) modulates experimental pressure pain thresholds and if this is related to observed alterations in cortical excitability. Method 15 healthy, male participants received 10 min 1 mA anodal, cathodal and sham tDCS to the left M1 before 15 min 1 Hz rTMS in separate sessions over a period of 3 weeks. Motor cortical excitability was recorded at baseline, post-tDCS priming and post-rTMS through recording motor evoked potentials (MEPs) from right FDI muscle. Pressure pain thresholds were determined by quantitative sensory testing (QST) through a computerized algometer, on the palmar thenar of the right hand pre- and post-stimulation. Results Cathodal tDCS-primed 1 Hz-rTMS was found to reverse the expected suppressive effect of 1 Hz rTMS on cortical excitability; leading to an overall increase in activity (p<0.001) with a parallel increase in pressure pain thresholds (p<0.01). In contrast, anodal tDCS-primed 1 Hz-rTMS resulted in a corresponding decrease in cortical excitability (p<0.05), with no significant effect on pressure pain. Conclusion This study demonstrates that priming the M1 before stimulation of 1 Hz-rTMS modulates experimental pressure pain thresholds in a safe and controlled manner, producing a form of analgesia. PMID:24658333

Moloney, Tonya M.; Witney, Alice G.

2014-01-01

61

Focal transcranial magnetic stimulation and response bias in a forced-choice task  

Microsoft Academic Search

The effects of transcranial magnetic stimulation were studied on the performance of a warned, forced-choice response time task by normal adults. The task consisted of extension of the index finger in response to the click produced by the discharge of the magnetic coil (go-signal). The subjects were asked to choose the right or left finger only after the go-signal was

J. P. Brasil-neto; A Pascual-Leone; J Valls-Solé; L G Cohen; M Hallett

1992-01-01

62

Direct and indirect activation of human corticospinal neurons by transcranial magnetic and electrical stimulation  

Microsoft Academic Search

Corticospinal volleys and surface electromyographic (EMG) responses evoked by magnetic and electrical transcranial stimulation were recorded simultaneously in three conscious human subjects. For magnetic stimulation, the figure-of-eight coil was held on the hand motor area either with the induced current through the brain flowing in a postero-anterior direction (P-A stimulation) or in a latero-medial direction (L-M stimulation). For electrical stimulation,

Hiroshi Nakamura; Hideki Kitagawa; Yoshiharu Kawaguchi; Haruo Tsuji

1996-01-01

63

Diagnostic relevance of transcranial magnetic and electric stimulation of the facial nerve in the management of facial palsy  

Microsoft Academic Search

ObjectiveEarlier investigations have suggested that isolated conduction block of the facial nerve to transcranial magnetic stimulation early in the disorder represents a very sensitive and potentially specific finding in Bell's palsy differentiating the disease from other etiologies.

Dennis A. Nowak; Stefan Linder; Helge Topka

2005-01-01

64

Repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex and cortical excitability in patients with major depressive disorder  

Microsoft Academic Search

Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex is a relatively non-invasive technique with putative therapeutic effects in major depression. However, the exact neurophysiological basis of these effects needs further clarification. Therefore, we studied the impact of ten daily sessions of left, dorsolateral prefrontal rTMS on motor cortical excitability, as revealed by transcranial magnetic stimulation-elicited motor-evoked potentials in

Malek Bajbouj; Eva-Lotta Brakemeier; Florian Schubert; Undine E. Lang; Peter Neu; Christina Schindowski; Heidi Danker-Hopfe

2005-01-01

65

Cognitive effects of high-frequency repetitive transcranial magnetic stimulation: a systematic review  

Microsoft Academic Search

Transcranial magnetic stimulation (TMS) was introduced as a non-invasive tool for the investigation of the motor cortex. The\\u000a repetitive application (rTMS), causing longer lasting effects, was used to study the influence on a variety of cerebral functions.\\u000a High-frequency (>1 Hz) rTMS is known to depolarize neurons under the stimulating coil and to indirectly affect areas being\\u000a connected and related to emotion

Birgit Guse; Peter Falkai; Thomas Wobrock

2010-01-01

66

Perioperative lesions of the facial nerve: follow-up investigations using transcranial magnetic stimulation  

Microsoft Academic Search

Peripheral facial palsy can occur after aural surgery and neurosurgery. Routine neurophysiological investigation (utilizing\\u000a electrical stimulation and the blink reflex) does not allow the direct assessment of the site of a lesion. In the present\\u000a study transcranial magnetic stimulation (TMS) was applied in order to evaluate the usefulness of this method for prognosis.\\u000a Twenty-three patients with postoperative facial pareses (after

S. Kotterba; M. Tegenthoff; J.-P. Malin

1997-01-01

67

Transcranial magnetic stimulation: studying the brain-behaviour relationship by induction of 'virtual lesions'.  

PubMed Central

Transcranial magnetic stimulation (TMS) provides a non-invasive method of induction of a focal current in the brain and transient modulation of the function of the targeted cortex. Despite limited understanding about focality and mechanisms of action, TMS provides a unique opportunity of studying brain-behaviour relations in normal humans. TMS can enhance the results of other neuroimaging techniques by establishing the causal link between brain activity and task performance, and by exploring functional brain connectivity. PMID:10466148

Pascual-Leone, A; Bartres-Faz, D; Keenan, J P

1999-01-01

68

Studying the Effects of Transcranial Direct-Current Stimulation in Stroke Recovery Using Magnetic Resonance Imaging  

PubMed Central

Transcranial direct-current stimulation (tDCS) is showing increasing promise as an adjunct therapy in stroke rehabilitation. However questions still remain concerning its mechanisms of action, which currently limit its potential. Magnetic resonance (MR) techniques are increasingly being applied to understand the neural effects of tDCS. Here, we review the MR evidence supporting the use of tDCS to aid recovery after stroke and discuss the important open questions that remain. PMID:24376413

Stagg, Charlotte J.; Johansen-Berg, Heidi

2013-01-01

69

Modulatory effects of high-frequency repetitive transcranial magnetic stimulation on the ipsilateral silent period  

Microsoft Academic Search

In healthy subjects, suprathreshold repetitive transcranial magnetic stimulation (rTMS) at frequencies >2 Hz prolongs the cortical silent period (CSP) over the course of the train. This progressive lengthening probably reflects temporal summation of the inhibitory interneurons in the stimulated primary motor cortex (M1). In this study, we tested whether high-frequency rTMS also modulates the ipsilateral silent period (ISP). In nine normal

M. Cincotta; F. Giovannelli; A. Borgheresi; F. Balestrieri; G. Zaccara; M. Inghilleri; A. Berardelli

2006-01-01

70

Navigated and Robotized Transcranial Magnetic Stimulation based on 3D Laser Scans  

Microsoft Academic Search

\\u000a Navigated and robotized Transcranial Magnetic Stimulation (TMS) is advancing forward in research and treatment. MRI-scans\\u000a or other medical image data are typically used as navigation source. Unfortunately, scanning time is always short and expensive.\\u000a For many TMSapplications the underlying brain topology is not necessarily needed. Therefore, we generate the subject’s head\\u000a contour for a precise stimulation from 3D laser scans.

Lars Richter; Ralf Bruder; Peter Trillenberg; Achim Schweikard

71

Non-invasive Transcranial Magnetic Stimulation (TMS) of the Motor Cortex for Neuropathic Pain—At the Tipping Point?  

PubMed Central

The term “neuropathic pain” (NP) refers to chronic pain caused by illnesses or injuries that damage peripheral or central pain-sensing neural pathways to cause them to fire inappropriately and signal pain without cause. Neuropathic pain is common, complicating diabetes, shingles, HIV, and cancer. Medications are often ineffective or cause various adverse effects, so better approaches are needed. Half a century ago, electrical stimulation of specific brain regions (neuromodulation) was demonstrated to relieve refractory NP without distant effects, but the need for surgical electrode implantation limited use of deep brain stimulation. Next, electrodes applied to the dura outside the brain’s surface to stimulate the motor cortex were shown to relieve NP less invasively. Now, electromagnetic induction permits cortical neurons to be stimulated entirely non-invasively using transcranial magnetic stimulation (TMS). Repeated sessions of many TMS pulses (rTMS) can trigger neuronal plasticity to produce long-lasting therapeutic benefit. Repeated TMS already has US and European regulatory approval for treating refractory depression, and multiple small studies report efficacy for neuropathic pain. Recent improvements include “frameless stereotactic” neuronavigation systems, in which patients’ head MRIs allow TMS to be applied to precise underlying cortical targets, minimizing variability between sessions and patients, which may enhance efficacy. Transcranial magnetic stimulation appears poised for the larger trials necessary for regulatory approval of a NP indication. Since few clinicians are familiar with TMS, we review its theoretical basis and historical development, summarize the neuropathic pain trial results, and identify issues to resolve before large-scale clinical trials. PMID:24228166

Treister, Roi; Lang, Magdalena; Klein, Max M.; Oaklander, Anne Louise

2013-01-01

72

Responses of human single motor units to transcranial magnetic stimulation.  

PubMed

Transcranial electromagnetic brain stimuli elicit a complex response in the electromyogram of active human hand muscles. Relatively weak stimuli evoke a short-latency primary response via a presumably monosynaptic corticospinal path. This is followed by a silent period that is terminated by a second peak at a latency of 50-80 ms. The responses evoked in single motor units in flexor digitorum profundus (FDP) were recorded. Responses were elicited at the second-peak latency only in trials in which no primary response was elicited in that unit, and only when the stimulus was given during the first half of the interspike interval (ISI). When given during the second half of the ISI, the same stimulus evoked a primary response but no second peak response. Stronger stimuli suppressed the second peak by evoking a primary response in more trials. Having discharged at about 20 ms latency, the parent motoneurone was unable to discharge again at second-peak latency, 30-60 ms later. The response at second-peak latency was not modified by disengaging both FDP and the extensors of the distal interphalangeal joint. Hence, this response is not secondary to a stretch reflex provoked by activation of the finger extensors, nor is it the result of a cutaneous signal resulting from movement of the finger. The latencies suggest that the corticospinal volley evokes a beta-motoneurone-mediated twitch in FDP muscle spindles, which elicits an afferent volley that activates the motoneurone reflexly. The first 100 ms or so of the silent period is due to the realignment of the first post-stimulus spike in most trials to corticospinal latency; i.e. this is not necessarily the result of an inhibitory or disfacilitatory process. Still stronger stimuli increase the duration of the ISI in which the stimulus is given, indicating the presence of an inhibitory/disfacilitatory process. PMID:9152201

Garland, S J; Miles, T S

1997-04-01

73

Co-registration of magnetic resonance spectroscopy and transcranial magnetic stimulation.  

PubMed

Transcranial magnetic stimulation (TMS) is a widely used tool for noninvasive modulation of brain activity, that is thought to interact primarily with excitatory and inhibitory neurotransmitter systems. Neurotransmitters such as glutamate and GABA can be measured by magnetic resonance spectroscopy (MRS). An important prerequisite for studying the relationship between MRS neurotransmitter levels and responses to TMS is that both modalities should examine the same regions of brain tissue. However, co-registration of TMS and MRS has been little studied to date. This study reports on a procedure for the co-registration and co-visualization of MRS and TMS, successfully localizing the hand motor cortex, as subsequently determined by its functional identification using TMS. Sixteen healthy subjects took part in the study; in 14 of 16 subjects, the TMS determined location of motor activity intersected the (2.5cm)(3) voxel selected for MRS, centered on the so called 'hand knob' of the precentral gyrus. It is concluded that MRS voxels placed according to established anatomical landmarks in most cases agree well with functional determination of the motor cortex by TMS. Reasons for discrepancies are discussed. PMID:25561395

Hone-Blanchet, Antoine; Salas, Rachel E; Celnik, Pablo; Kalloo, Aadi; Schar, Michael; Puts, Nicolaas A J; Harris, Ashley D; Barker, Peter B; Fecteau, Shirley; Earley, Christopher J; Allen, Richard P; Edden, Richard A

2015-03-15

74

Electromagnetic Field Modeling of Transcranial Electric and Magnetic Stimulation: Targeting, Individualization, and Safety of Convulsive and Subconvulsive Applications  

NASA Astrophysics Data System (ADS)

The proliferation of noninvasive transcranial electric and magnetic brain stimulation techniques and applications in recent years has led to important insights into brain function and pathophysiology of brain-based disorders. Transcranial electric and magnetic stimulation encompasses a wide spectrum of methods that have developed into therapeutic interventions for a variety of neurological and psychiatric disorders. Although these methods are at different stages of development, the physical principle underlying these techniques is the similar. Namely, an electromagnetic field is induced in the brain either via current injection through scalp electrodes or via electromagnetic induction. The induced electric field modulates the neuronal transmembrane potentials and, thereby, neuronal excitability or activity. Therefore, knowledge of the induced electric field distribution is key in the design and interpretation of basic research and clinical studies. This work aims to delineate the fundamental physical limitations, tradeoffs, and technological feasibility constraints associated with transcranial electric and magnetic stimulation, in order to inform the development of technologies that deliver safer, and more spatially, temporally, and patient specific stimulation. Part I of this dissertation expounds on the issue of spatial targeting of the electric field. Contrasting electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) configurations that differ markedly in efficacy, side effects, and seizure induction efficiency could advance our understanding of the principles linking treatment parameters and therapeutic outcome and could provide a means of testing hypotheses of the mechanisms of therapeutic action. Using the finite element method, we systematically compare the electric field characteristics of existing forms of ECT and MST. We introduce a method of incorporating a modality-specific neural activation threshold in the electric field models that can inform dosage requirements in convulsive therapies. Our results indicate that the MST electric field is more focal and more confined to the superficial cortex compared to ECT. Further, the conventional ECT current amplitude is much higher than necessary for seizure induction. One of the factors important to clinical outcome is seizure expression. However, it is unknown how the induced electric field is related to seizure onset and propagation. In this work, we explore the effect of the electric field distribution on the quantitative ictal electroencephalography and current source density in ECT and MST. We further demonstrate how the ECT electrode shape, size, spacing, and current can be manipulated to yield more precise control of the induced electric field. If desirable, ECT can be made as focal as MST while using simpler stimulation equipment. Next, we demonstrate how the electric field induced by transcranial magnetic stimulation (TMS) can be controlled. We present the most comprehensive comparison of TMS coil electric field penetration and focality to date. The electric field distributions of more than 50 TMS coils were simulated. We show that TMS coils differ markedly in their electric field characteristics, but they all are subject to a consistent depth-focality tradeoff. Specifically, the ability to directly stimulate deeper brain structures is obtained at the expense of inducing wider electric field spread. Figure-8 type coils are fundamentally more focal compared to circular type coils. Understanding the depth-focality tradeoff can help researchers and clinicians to appropriately select coils and interpret TMS studies. This work also enables the development of novel TMS coils with electronically switchable active and sham modes as well as for deep TMS. Design considerations of these coils are extensively discussed. Part II of the dissertation aims to quantify the effect of individual, sex, and age differences in head geometry and conductivity on the induced neural stimulation strength and focality of ECT and MST. Across and within ECT studies, there is

Deng, Zhi-De

75

Effects of Repetitive Transcranial Magnetic Stimulation in Performing Eye-Hand Integration Tasks: Four Preliminary Studies with Children Showing Low-Functioning Autism  

ERIC Educational Resources Information Center

This report, based on four studies with children with low-functioning autism, aimed at evaluating the effects of repetitive transcranial magnetic stimulation delivered on the left and right premotor cortices on eye-hand integration tasks; defining the long-lasting effects of high-frequency repetitive transcranial magnetic stimulation; and…

Panerai, Simonetta; Tasca, Domenica; Lanuzza, Bartolo; Trubia, Grazia; Ferri, Raffaele; Musso, Sabrina; Alagona, Giovanna; Di Guardo, Giuseppe; Barone, Concetta; Gaglione, Maria P.; Elia, Maurizio

2014-01-01

76

Two phases of intracortical inhibition revealed by transcranial magnetic threshold tracking  

Microsoft Academic Search

Intracortical inhibition was investigated in normal human volunteers by paired-pulse transcranial magnetic stimulation, using\\u000a a new, computer-assisted threshold-tracking method. Motor threshold was defined as the stimulus amplitude required to evoke\\u000a a motor evoked potential of 0.2 mV (peak-to-peak) in abductor pollicis brevis, and inhibition was measured as the percentage\\u000a increase in threshold, when the test stimulus was preceded by a subthreshold

R. J. Fisher; Y. Nakamura; S. Bestmann; J. C. Rothwell; H. Bostock

2002-01-01

77

Cortical inhibition in attention deficit hyperactivity disorder: new insights from the electroencephalographic response to transcranial magnetic stimulation.  

PubMed

Attention deficit hyperactivity disorder is one of the most frequent neuropsychiatric disorders in childhood. Transcranial magnetic stimulation studies based on muscle responses (motor-evoked potentials) suggested that reduced motor inhibition contributes to hyperactivity, a core symptom of the disease. Here we employed the N100 component of the electroencephalographic response to transcranial magnetic stimulation as a novel marker for a direct assessment of cortical inhibitory processes, which has not been examined in attention deficit hyperactivity disorder so far. We further investigated to what extent affected children were able to regulate motor cortical inhibition, and whether effects of age on the electroencephalographic response to transcranial magnetic stimulation were compatible with either a delay in brain maturation or a qualitatively different development. N100 amplitude evoked by transcranial magnetic stimulation and its age-dependent development were assessed in 20 children with attention deficit hyperactivity disorder and 19 healthy control children (8-14 years) by 64-channel electroencephalography. Amplitude and latency of the N100 component were compared at rest, during response preparation in a forewarned motor reaction time task and during movement execution. The amplitude of the N100 component at rest was significantly lower and its latency tended to be shorter in children with attention deficit hyperactivity disorder. Only in controls, N100 amplitude to transcranial magnetic stimulation was reduced by response preparation. During movement execution, N100 amplitude decreased while motor evoked potential amplitudes showed facilitation, indicating that the electroencephalographic response to transcranial magnetic stimulation provides further information on cortical excitability independent of motor evoked potential amplitudes and spinal influences. Children with attention deficit hyperactivity disorder showed a smaller N100 amplitude reduction during movement execution compared with control children. The N100 amplitude evoked by transcranial magnetic stimulation decreased with increasing age in both groups. The N100 reduction in children with attention deficit hyperactivity disorder at all ages suggests a qualitative difference rather than delayed development of cortical inhibition in this disease. Findings further suggest that top-down control of motor cortical inhibition is reduced in children with attention deficit hyperactivity disorder. We conclude that evoked potentials in response to transcranial magnetic stimulation are a promising new marker of cortical inhibition in attention deficit hyperactivity disorder during childhood. PMID:22492560

Bruckmann, Sarah; Hauk, Daniela; Roessner, Veit; Resch, Franz; Freitag, Christine M; Kammer, Thomas; Ziemann, Ulf; Rothenberger, Aribert; Weisbrod, Matthias; Bender, Stephan

2012-07-01

78

Evaluation of proximal facial nerve conduction by transcranial magnetic stimulation  

Microsoft Academic Search

A magnetic stimulator was used for direct transcutaneous stimulation of the intracranial portion of the facial nerve in 15 normal subjects and in patients with Bell's palsy, demyelinating neuropathy, traumatic facial palsy and pontine glioma. Compound muscle action potentials (CMAPs) thus elicited in the orbicularis oris muscle of controls were of similar amplitude but longer latency (1.3 SD 0.15 ms)

T N Schriefer; K R Mills; N M Murray; C W Hess

1988-01-01

79

Eccentric figure-eight coils for transcranial magnetic stimulation.  

PubMed

Previously we proposed an eccentric figure-eight coil that can cause threshold stimulation in the brain at lower driving currents. In this study, we performed numerical simulations and magnetic stimulations to healthy subjects for evaluating the advantages of the eccentric coil. The simulations were performed using a simplified spherical brain model and a realistic human brain model. We found that the eccentric coil required a driving current intensity of approximately 18% less than that required by the concentric coil to cause comparable eddy current densities within the brain. The eddy current localization of the eccentric coil was slightly higher than that of the concentric coil. A prototype eccentric coil was designed and fabricated. Instead of winding a wire around a bobbin, we cut eccentric-spiral slits on the insulator cases, and a wire was woven through the slits. The coils were used to deliver magnetic stimulation to healthy subjects; among our results, we found that the current slew rate corresponding to motor threshold values for the concentric and eccentric coils were 86 and 78 A/µs, respectively. The results indicate that the eccentric coil consistently requires a lower driving current to reach the motor threshold than the concentric coil. Future development of compact magnetic stimulators will enable the treatment of some intractable neurological diseases at home. PMID:25399864

Sekino, Masaki; Ohsaki, Hiroyuki; Takiyama, Yoshihiro; Yamamoto, Keita; Matsuzaki, Taiga; Yasumuro, Yoshihiro; Nishikawa, Atsushi; Maruo, Tomoyuki; Hosomi, Koichi; Saitoh, Youichi

2015-01-01

80

Transcranial magnetic stimulation of the visual cortex induces somatotopically organized qualia in blind subjects.  

PubMed

After loss of a particular sensory channel, the deprived cortex can be activated by inputs from other sensory modalities. It is not known whether activation of the rewired cortex evokes subjective experiences characteristic of that cortex or consistent with the rerouted sensory information. In a previous study, blind subjects were trained to perform visual tasks with a tongue display unit, a sensory substitution device that translates visual displays into electrotactile tongue stimulation. This cross-modal sensory stimulation activated their visual cortices. We now extend this finding by using transcranial magnetic stimulation to examine the perceptual correlates of training-induced plastic responses. We find that blind subjects proficient with the use of the tongue display unit report somatopically organized tactile sensations that are referred to the tongue when transcranial magnetic stimulation is applied over the occipital cortex. No such sensations were evoked in trained, blindfolded, seeing control subjects who performed the sensory substitution task equally well. These data show that the perceptual correlate of activity in a given cortical area reflects the characteristics of its novel sensory input source. PMID:16916936

Kupers, Ron; Fumal, Arnaud; de Noordhout, Alain Maertens; Gjedde, Albert; Schoenen, Jean; Ptito, Maurice

2006-08-29

81

Transcranial magnetic stimulation of the visual cortex induces somatotopically organized qualia in blind subjects  

PubMed Central

After loss of a particular sensory channel, the deprived cortex can be activated by inputs from other sensory modalities. It is not known whether activation of the rewired cortex evokes subjective experiences characteristic of that cortex or consistent with the rerouted sensory information. In a previous study, blind subjects were trained to perform visual tasks with a tongue display unit, a sensory substitution device that translates visual displays into electrotactile tongue stimulation. This cross-modal sensory stimulation activated their visual cortices. We now extend this finding by using transcranial magnetic stimulation to examine the perceptual correlates of training-induced plastic responses. We find that blind subjects proficient with the use of the tongue display unit report somatopically organized tactile sensations that are referred to the tongue when transcranial magnetic stimulation is applied over the occipital cortex. No such sensations were evoked in trained, blindfolded, seeing control subjects who performed the sensory substitution task equally well. These data show that the perceptual correlate of activity in a given cortical area reflects the characteristics of its novel sensory input source. PMID:16916936

Kupers, Ron; Fumal, Arnaud; de Noordhout, Alain Maertens; Gjedde, Albert; Schoenen, Jean; Ptito, Maurice

2006-01-01

82

Noninvasive brain stimulation with transcranial magnetic or direct current stimulation (TMS\\/tDCS)—From insights into human memory to therapy of its dysfunction  

Microsoft Academic Search

Noninvasive stimulation of the brain by means of transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) has driven important discoveries in the field of human memory functions. Stand-alone or in combination with other brain mapping techniques noninvasive brain stimulation can assess issues such as location and timing of brain activity, connectivity and plasticity of neural circuits and functional

Roland Sparing; Felix M. Mottaghy

2008-01-01

83

BRAIN initiative: Transcranial magnetic stimulation automation and calibration.  

PubMed

In this paper, we introduced an automated TMS system with robot control and optical sensor combined with neuronavigation software. By using the robot, the TMS coil can be accurately positioned over any preselected brain region. The neuronavigation system provides an accurate positioning of a magnetic coil in order to induce a specific cortical excitation. An infrared optical measurement device is also used in order to detect and compensate for head movements of the patient. This procedure was simulated using a PC based robotic simulation program. The proposed automated robot system is integrated with TMS numerical solver and allows users to actually see the depth, location, and shape of the induced eddy current on the computer monitor. PMID:25570006

Todd, Garth D; Abdellatif, Ahmed; Sabouni, Abas

2014-08-01

84

Post-exercise facilitation and depression of motor evoked potentials to transcranial magnetic stimulation: a study in multiple sclerosis  

Microsoft Academic Search

Objective: To evaluate motor cortex excitability changes by transcranial magnetic stimulation (TMS) following repetitive muscle contractions in patients with multiple sclerosis (MS); to state whether a typical pattern of post-exercise motor evoked potentials (MEPs) is related to clinical fatigue in MS.Methods: In 41 patients with definite MS (32 with fatigue and 9 without fatigue according to Fatigue Severity Scale) and

A Perretti; P Balbi; G Orefice; L Trojano; L Marcantonio; V Brescia-Morra; S Ascione; F Manganelli; G Conte; L Santoro

2004-01-01

85

Enhancing the quality of studies using transcranial magnetic and electrical stimulation with a new computer-controlled system  

Microsoft Academic Search

Transcranial magnetic (TMS) and electrical (TES) stimulation of the human brain have become useful tools in neurophysiological and neuropsychological research. Here we describe an integrated system that allows experimental control, data recording and analysis of neurophysiological and neuropsychological TMS and TES procedures (including motor thresholds, recruitment curves, intracortical inhibition and facilitation with paired pulses). The system uses a multifunction input\\/output

A Kaelin-Lang; L. G Cohen

2000-01-01

86

Contralateral and ipsilateral EMG responses to transcranial magnetic stimulation during recovery of arm and hand function after stroke  

Microsoft Academic Search

We examined the relationship between the recovery of hand and arm function in a group of hemiplegic stroke patients and the presence of short-latency EMG responses to transcranial magnetic stimulation (TMS) in 4 different upper limb muscles (deltoid, biceps, extensor digitorum communis and the first dorsal interosseous). Twenty-one patients were examined within 5 weeks of stroke (median 2 weeks), and

A. Turton; S. Wroe; N. Trepte; C. Fraser; R. N. Lemon

1996-01-01

87

Interhemispheric asymmetries in the perception of unimanual and bimanual cutaneous stimuli: A study using transcranial magnetic stimulation  

Microsoft Academic Search

Summary Previous studies have shown that transcranial magnetic stimulation (TMS) of the sensorimotor cortex can induce a suppression of cutaneous perception from the fingers of the contralateral hand. In this work, 17 normal subjects were submitted to focal TMS of frontal and parietal scalp sites of each hemisphere. TMS was delivered at two interstimulus intervals (20 and 40 ms) following

M. Oliveri; P. M. Rossini; P. Pasqualetti; R. Traversa; P. Cicinelli; M. G. Palmieri; F. Tomaiuolo; C. Caltagirone

1999-01-01

88

Comparison of motor effects following subcortical electrical stimulation through electrodes in the globus pallidus internus and cortical transcranial magnetic stimulation  

Microsoft Academic Search

Current concepts of transcranial magnetic stimulation (TMS) over the primary motor cortex are still under debate as to whether inhibitory motor effects are exclusively of cortical origin. To further elucidate a potential subcortical influence on motor effects, we combined TMS and unilateral subcortical electrical stimulation (SES) of the corticospinal tract. SES was performed through implanted depth electrodes in eight patients

Andrea A. Kühn; Stephan A. Brandt; Andreas Kupsch; Thomas Trottenberg; Jan Brocke; Kerstin Irlbacher; Gerd H. Schneider; Bernd-Ulrich Meyer

2004-01-01

89

The silent period induced by transcranial magnetic stimulation in muscles supplied by cranial nerves: normal data and changes in patients  

Microsoft Academic Search

The silent period induced by transcranial magnetic stimulation of the sensorimotor cortex (Magstim 200, figure of eight coil, loop diameter 7 cm) in active muscles supplied by cranial nerves (mentalis, sternocleidomastoid, and genioglossus) was studied in 14 control subjects and nine patients with localised lesions of the sensorimotor cortex. In the patients, measurements of the silent period were also made

K J Werhahn; J Classen; R Benecke

1995-01-01

90

Impaired cortico-bulbar tract function in dysarthria due to hemispheric stroke. Functional testing using transcranial magnetic stimulation  

Microsoft Academic Search

Summary We investigated cortico-lingual and cortico-orofacial tract contralateral orofacial responses were either absent (13 patients) or delayed (one patient). According to the function utilizing transcranial magnetic stimulation in 18 consecutive patients with dysarthria due to hemispheric electrophysiological findings, all lesions revealed by CT or MRI, were located within the pyramidal tract at the lower stroke. Delayed responses (conduction time .

P. P. Urban; H. C. Hopf; S. Fleischer; P. G. Zorowka; W. Muller-Forell

1997-01-01

91

Modulation of N400 in Chronic Non-Fluent Aphasia Using Low Frequency Repetitive Transcranial Magnetic Stimulation (rTMS)  

ERIC Educational Resources Information Center

Low frequency Repetitive Transcranial Magnetic Stimulation (rTMS) has previously been applied to language homologues in non-fluent populations of persons with aphasia yielding significant improvements in behavioral language function up to 43 months post stimulation. The present study aimed to investigate the electrophysiological correlates…

Barwood, Caroline H. S.; Murdoch, Bruce E.; Whelan, Brooke-Mai; Lloyd, David; Riek, Stephan; O'Sullivan, John D.; Coulthard, Alan; Wong, Andrew

2011-01-01

92

Stimulating Conversation: Enhancement of Elicited Propositional Speech in a Patient with Chronic Non-Fluent Aphasia following Transcranial Magnetic Stimulation  

ERIC Educational Resources Information Center

Although evidence suggests that patients with left hemisphere strokes and non-fluent aphasia who receive 1Hz repetitive transcranial magnetic stimulation (rTMS) over the intact right inferior frontal gyrus experience persistent benefits in naming, it remains unclear whether the effects of rTMS in these patients generalize to other language…

Hamilton, Roy H.; Sanders, Linda; Benson, Jennifer; Faseyitan, Olufunsho; Norise, Catherine; Naeser, Margaret; Martin, Paula; Coslett, H. Branch

2010-01-01

93

Cortical Inhibition in Attention Deficit Hyperactivity Disorder: New Insights from the Electroencephalographic Response to Transcranial Magnetic Stimulation  

ERIC Educational Resources Information Center

Attention deficit hyperactivity disorder is one of the most frequent neuropsychiatric disorders in childhood. Transcranial magnetic stimulation studies based on muscle responses (motor-evoked potentials) suggested that reduced motor inhibition contributes to hyperactivity, a core symptom of the disease. Here we employed the N100 component of the…

Bruckmann, Sarah; Hauk, Daniela; Roessner, Veit; Resch, Franz; Freitag, Christine M.; Kammer, Thomas; Ziemann, Ulf; Rothenberger, Aribert; Weisbrod, Matthias; Bender, Stephan

2012-01-01

94

A Preliminary Transcranial Magnetic Stimulation Study of Cortical Inhibition and Excitability in High-Functioning Autism and Asperger Disorder  

ERIC Educational Resources Information Center

Aim: Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS). Method: Participants were diagnosed by…

Enticott, Peter G.; Rinehart, Nicole J.; Tonge, Bruce J.; Bradshaw, John L.; Fitzgerald, Paul B.

2010-01-01

95

The Observation of Manual Grasp Actions Affects the Control of Speech: A Combined Behavioral and Transcranial Magnetic Stimulation Study  

ERIC Educational Resources Information Center

Does the mirror system affect the control of speech? This issue was addressed in behavioral and Transcranial Magnetic Stimulation (TMS) experiments. In behavioral experiment 1, participants pronounced the syllable /da/ while observing (1) a hand grasping large and small objects with power and precision grasps, respectively, (2) a foot interacting…

Gentilucci, Maurizio; Campione, Giovanna Cristina; Volta, Riccardo Dalla; Bernardis, Paolo

2009-01-01

96

Effect of the different winding methods of coil on electromagnetic field during transcranial magnetic stimulation.  

PubMed

Transcranial magnetic stimulation (TMS) is a powerful, non-invasive tool for investigating functions in the brain. The target inside the head is stimulated with eddy currents induced in the tissues by the time-varying magnetic field. TMS has been used in several applications in medical and clinical research which include brain mapping, treatment of mood disorder and schizophrenia, treatment of epilepsy, treatment of chronic pain and so on. The stimulation effect can be affected by the stimulation intensity. For coils with the same shape, different winding methods make the coil have different stimulation intensity. In this paper, three different methods for winding circular coils are discussed. The electromagnetic fields induced by the three different circular coils were analyzed. The results show that the circular coil with the pancake coil winding has the strongest stimulation intensity. PMID:19163656

Yang, Shuo; Xu, Guizhi; Wang, Lei; Zhang, Xiu

2008-01-01

97

FDTD-based Transcranial Magnetic Stimulation model applied to specific neurodegenerative disorders.  

PubMed

Non-invasive treatment of neurodegenerative diseases is particularly challenging in Western countries, where the population age is increasing. In this work, magnetic propagation in human head is modelled by Finite-Difference Time-Domain (FDTD) method, taking into account specific characteristics of Transcranial Magnetic Stimulation (TMS) in neurodegenerative diseases. It uses a realistic high-resolution three-dimensional human head mesh. The numerical method is applied to the analysis of magnetic radiation distribution in the brain using two realistic magnetic source models: a circular coil and a figure-8 coil commonly employed in TMS. The complete model was applied to the study of magnetic stimulation in Alzheimer and Parkinson Diseases (AD, PD). The results show the electrical field distribution when magnetic stimulation is supplied to those brain areas of specific interest for each particular disease. Thereby the current approach entails a high potential for the establishment of the current underdeveloped TMS dosimetry in its emerging application to AD and PD. PMID:25453382

Fanjul-Vélez, Félix; Salas-García, Irene; Ortega-Quijano, Noé; Arce-Diego, José Luis

2015-01-01

98

How do high- and low-frequency repetitive transcranial magnetic stimulations modulate the temporal cortex.  

PubMed

Few studies have examined the impact of repetitive transcranial magnetic stimulation (rTMS) on the cortical excitability of nonmotor cortices; current treatments often target the temporal or prefrontal cortex. We used auditory evoked potentials recorded in 24 healthy subjects to evaluate the neuromodulatory effects of low- and high-frequency rTMS in the temporal lobe. Both auditory evoked potential P50 amplitude, a marker of cortical excitability, and P50 ratio, a marker of sensory gating known to be impaired in patients with auditory verbal hallucinations, were compared before and after rTMS. We observed a similar effect after both stimulation frequencies, with a decrease in P50 amplitude and no significant effect on P50 ratio. Low- and high-frequency rTMS applied to the temporal lobe seemed to exert the same cortical neuromodulation effect, while auditory sensory gating may not be modulated by temporal rTMS. PMID:25223883

Nathou, Clement; Etard, Olivier; Simon, Gregory; Dollfus, Sonia

2015-02-01

99

A Novel Transcranial Magnetic Stimulator Inducing Near Rectangular Pulses with Controllable Pulse Width (cTMS)  

PubMed Central

A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 7 kA, enabling PW control from 5 ?s to over 100 ?s. The near-rectangular induced electric field pulses use 22–34% less energy and generate 67–72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 ?s, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications. PMID:18232369

Jalinous, Reza; Lisanby, Sarah H.

2013-01-01

100

Neural field theory of calcium dependent plasticity with applications to transcranial magnetic stimulation.  

PubMed

Calcium dependent plasticity (CaDP), a physiologically realistic plasticity mechanism in the microscopic regime, is incorporated into a neural field theory to explore system-level plasticity. This system-level plasticity model is capable of reproducing the characteristic plasticity window of spike-timing dependent plasticity (STDP) in paired associative stimulation (PAS), where a peripheral electric pulse stimulation is paired to transcranial magnetic stimulation (TMS) in the cortex, and rTMS frequency dependent plasticity, where low and high frequency rTMS trains induce depression and potentiation, respectively. These thus reproduce experimental results for system-level plasticity for the first time. This also bridges the gap between microscopic plasticity theory and system-level plasticity observed experimentally, and addresses long standing problems of stability and adaptability by predicting stable plasticity, a possible seizure state where neurons fire at a high rate, and spike-rate adaptation. PMID:23376643

Fung, P K; Robinson, P A

2013-05-01

101

[The use of repetitive transcranial magnetic stimulation (rTMS) in auditory verbal hallucinations (AVH)].  

PubMed

Up to one-third of all schizophrenic patients suffer from auditory verbal hallucinations (AVH) that are resistant to antipsychotics. The use of repetitive transcranial magnetic stimulation (rTMS) is a therapeutic option that may disrupt or attenuate treatment resistant (TR) AVHs. This article reviews the available literature on the use of rTMS to treat AVHs, particularly focusing on randomised controlled trials, which have introduced new definitions ("refractory AVHs"), and techniques (active comparator strategies and imaging-guided rTMS). A number of meta-analyses are considered, which support a range of positive effect sizes for AVH attenuation in response to rTMS. Larger maintenance and follow-up studies with clearer clinical definitions of TR AVH are required. The underlying mechanism of action of rTMS on language networks needs further clarification and future trials should focus on methods for assessing AVH changes, time courses of response, and the development of response markers. PMID:20648414

Jandl, M

2010-11-01

102

Update on repetitive transcranial magnetic stimulation in obsessive-compulsive disorder: different targets.  

PubMed

Obsessive-compulsive disorder (OCD) is a chronic, disabling disorder. Ten percent of patients remain treatment refractory despite several treatments. For these severe, treatment-refractory patients, repetitive transcranial magnetic stimulation (rTMS) has been suggested as a treatment option. Since 1997, in published trials, a total of 110 OCD patients have been treated with rTMS. This review aims to provide an update on rTMS treatment in patients with OCD. First, the mechanism of action is discussed, followed by the efficacy and side effects of rTMS at various brain targets, and finally implications for the future. Due to the lack of studies with comparable stimulation or treatment parameters and with reliable designs, it is difficult to draw clear conclusions. In general, rTMS appears to be effective in open-label studies; however, this has not yet been replicated in randomized, sham-controlled trials. PMID:21547545

Blom, Rianne M; Figee, Martijn; Vulink, Nienke; Denys, Damiaan

2011-08-01

103

Long-term repetitive transcranial magnetic stimulation therapy: new research questions arising from one tinnitus case?  

PubMed

Tinnitus may become refractory to treatment and disabling. Brain transcranial magnetic stimulation (TMS) has shown promise as a therapy, but has been employed primarily short-term. We treated a patient with 5 weeks of weekly repetitive TMS (rTMS), followed by 6 months of monthly rTMS. He was a 75-year-old dentist with chronic tinnitus from occupational noise exposure. Physical examination and MRIs of the auditory canals and brain had revealed no lesions. The patient showed a general gradual, progressive improvement on per cent of severe tinnitus diary days (from baseline 100% to 33%), tinnitus handicap inventory (from baseline score 70 to 18), and mini-tinnitus questionnaire (from baseline score 17 to 6). No changes occurred in serial audiograms. Transient adverse events were a headache during stimulation, and dizziness 30 min after treatment. Implications and questions for future non-invasive neuromodulation clinical research raised by our case are discussed. PMID:25538216

Labar, Douglas Richard; Cortes, Mar; Edwards, Dylan

2014-01-01

104

Functional Neurosurgery in the Human Thalamus by Transcranial Magnetic Resonance Guided Focused Ultrasound  

NASA Astrophysics Data System (ADS)

Potential applications of Transcranial Magnetic Resonance guided Focused Ultrasound (TcMRgFUS) include treatment of functional brain disorders, such as Parkinson's disease, dystonia and tremor, neurogenic pain and tinnitus, neuropsychiatric disorders and epilepsy. In this study we demonstrate the feasibility of non-invasive TcMRgFUS ablation of clinically well established targets in the human thalamus that are currently accessed stereotactically by interventional strategies based on the concept of the thalamocortical dysrhythmia (TCD). Thermal hotspots suitable for clinical intervention were created successfully in anatomical preparations of human ex-vivo heads under pseudo clinical conditions. The hotspots could be positioned at the target locations as needed and local energy deposition was sufficient to create tissue ablation. Numerical simulations based on these experimental data predict that the acoustic energy needed to create ablative lesions in-vivo will be within limits that can safely applied.

Werner, Beat; Morel, Anne; Jeanmonod, Daniel; Martin, Ernst

2009-04-01

105

Assessment and modulation of neuroplasticity in rehabilitation with transcranial magnetic stimulation  

PubMed Central

Despite intensive efforts towards the improvement of outcomes after acquired brain injury functional recovery is often limited. One reasons is the challenge in assessing and guiding plasticity after brain injury. In this context, Transcranial Magnetic Stimulation (TMS) - a noninvasive tool of brain stimulation - could play a major role. TMS has shown to be a reliable tool to measure plastic changes in the motor cortex associated with interventions in the motor system; such as motor training and motor cortex stimulation. In addition, as illustrated by the experience in promoting recovery from stroke, TMS a promising therapeutic tool to minimize motor, speech, cognitive, and mood deficits. In this review, we will focus on stroke to discuss how TMS can provide insights into the mechanisms of neurological recovery, and can be used for measurement and modulation of plasticity after an acquired brain insult. PMID:21172687

Bashir, Shahid; Mizrahi, Ilan; Weaver, Kayleen; Fregni, Felipe; Pascual-Leone, Alvaro

2013-01-01

106

Transcranial magnetic stimulation selectively impairs interhemispheric transfer of visuo-motor information in humans.  

PubMed

We investigated the cerebral cortical route by which visual information reaches motor cortex when visual signals are used for manual responses. Subjects responded unimanually to photic stimuli delivered to the hemifield ipsilateral or contralateral to the moving hand. On some trials, trans-cranial magnetic stimulation (TMS) was applied unilaterally over the occiput, with the aim of stimulating extrastriate visual areas and thereby modifying transmission of visual input. In association with the side of a visual stimulus and a motor response, TMS could change inter- or intra-hemispheric transmission needed to convey visual information to motor areas. Reaction time differences following TMS suggested that TMS exerted an inhibitory effect only when visuo-motor information had to be transferred interhemispherically. This result reinforces evidence for an extrastriate pathway of interhemispheric transfer of visuomotor information. PMID:9497152

Marzi, C A; Miniussi, C; Maravita, A; Bertolasi, L; Zanette, G; Rothwell, J C; Sanes, J N

1998-02-01

107

[Functional neuroimaging and the treatment of aphasia: speech therapy and repetitive transcranial magnetic stimulation].  

PubMed

Functional imaging has provided new evidence of the neurobiological impact of the treatment of aphasia, including speech therapy, through the alteration of the activated language neural network. In such a way, speech therapy has proved its impact. The role of each hemisphere is still very unclear. Some of the authors link the left-lateralisation of activations to the therapeutic improvement of language and the right-activated network to a maladaptative strategy, whereas others consider the latter as a useful compensatory network for speech disorders. Repetitive trans-cranial magnetic stimulation (rTMS), first used to determine cortical activity, is now used to directly interfere with cerebral activity. In the years to come, rTMS should be developed as an adjuvant therapy for aphasia. PMID:18675046

de Boissezon, X; Raboyeau, G; Simonetta-Moreau, M; Puel, M; Démonet, J F; Cardebat, D

2008-05-01

108

Maintaining remission of depression with repetitive transcranial magnetic stimulation during pregnancy: a case report.  

PubMed

It is important to explore potential safe treatment options for the ongoing treatment of women's depression during pregnancy. One promising treatment is repetitive transcranial magnetic stimulation (rTMS). We report on the case of a woman who became pregnant while receiving regular maintenance rTMS combined with pharmacotherapy treatment for major depressive episode. The patient achieved remission following two acute courses of rTMS and continued with maintenance rTMS treatment over the course of 4 years, during which she became pregnant and gave birth to a healthy infant. Her remission was maintained over this time including during and after her pregnancy. There were no adverse effects to the patient or her infant during the pregnancy or in the post-natal period. Maintenance rTMS may be an effective and feasible treatment option for depression during pregnancy. PMID:24638141

Burton, Cassandra; Gill, Shane; Clarke, Patrick; Galletly, Cherrie

2014-06-01

109

Simultaneous transcranial magnetic stimulation and single neuron recording in alert non-human primates  

PubMed Central

Transcranial magnetic stimulation (TMS) is a widely used, noninvasive method for stimulating nervous tissue, yet its mechanisms of effect are poorly understood. Here we report novel methods for studying the influence of TMS on single neurons in the brain of alert non-human primates. We designed a TMS coil that focuses its effect near the tip of a recording electrode and recording electronics that enable direct acquisition of neuronal signals at the site of peak stimulus strength minimally perturbed by stimulation artifact in intact, awake monkeys (Macaca mulatta). We recorded action potentials within ~1 ms after 0.4 ms TMS pulses and observed changes in activity that differed significantly for active stimulation as compared to sham stimulation. The methodology is compatible with standard equipment in primate laboratories, allowing for easy implementation. Application of these new tools will facilitate the refinement of next generation TMS devices, experiments, and treatment protocols. PMID:24974797

Mueller, Jerel K.; Grigsby, Erinn M.; Prevosto, Vincent; Petraglia, Frank W.; Rao, Hrishikesh; Deng, Zhi-De; Peterchev, Angel V.; Sommer, Marc A.; Egner, Tobias; Platt, Michael L.; Grill, Warren M.

2014-01-01

110

Surgical leg rotation: cortical neuroplasticity assessed through brain mapping using transcranial magnetic stimulation  

PubMed Central

Rotationplasty (Borggreve-Van Nes operation) is a rare limb salvage procedure, most often applied to children presenting with sarcoma of the distal femur. In type A1 operation, the distal thigh is removed and the proximal tibia is axially rotated by 180°, remodeled, grafted onto the femoral stump, and then prosthetized. The neurovascular bundle is spared. The rotated ankle then works as a knee. The foot plantar and dorsal flexors act as knee extensors and flexors, respectively. Functional results may be excellent. Cortical neuroplasticity was studied in three men (30–31 years) who were operated on the left lower limb at ages between 7 and 11 years and were fully autonomous with a custom-made prosthesis, as well as in three age–sex matched controls. The scalp stimulation coordinates, matching the patients’ brain MRI spots, were digitized through a ‘neuronavigation’ optoelectronic system, in order to guide the transcranial magnetic stimulation coil, thus ensuring spatial precision during the procedure. Through transcranial magnetic stimulation driven by neuronavigation, the cortical representations of the contralateral soleus and vastus medialis muscles were studied in terms of amplitude of motor evoked potentials (MEPs) and centering and width of the cortical areas from which the potentials could be evoked. Map centering on either hemisphere did not differ substantially across muscles and participants. In the operated patients, MEP amplitudes, the area from which MEPs could be evoked, and their product (volume) were larger for the muscles of the unaffected side compared with both the rotated soleus muscle (average effect size 0.75) and the muscles of healthy controls (average effect size 0.89). In controls, right–left differences showed an effect size of 0.38. In no case did the comparisons reach statistical significance (P>0.25). Nevertheless, the results seem consistent with cortical plasticity reflecting strengthening of the unaffected leg and a combination of cross-education and skill training of the rotated leg. PMID:25153790

Benedetti, Maria Grazia; Rota, Viviana; Manfrini, Marco; Perucca, Laura; Caronni, Antonio

2014-01-01

111

Risk and safety of repetitive transcranial magnetic stimulation: report and suggested guidelines from the International Workshop on the Safety of Repetitive Transcranial Magnetic Stimulation, June 5–7, 1996  

Microsoft Academic Search

Single-pulse transcranial magnetic stimulation (TMS) is a safe and useful tool for investigating various aspects of human neurophysiology, particularly corticospinal function, in health and disease. Repetitive TMS (rTMS), however, is a more powerful and potentially dangerous modality, capable of regionally blocking or facilitating cortical processes. Although there is evidence that rTMS is useful for treating clinical depression, and possibly other

Eric M. Wassermann

1998-01-01

112

Experimentation with a transcranial magnetic stimulation system for functional brain mapping.  

PubMed

We describe functional brain mapping experiments using a transcranial magnetic stimulation (TMS) device. This device, when placed on a subject's scalp, stimulates the underlying neurons by generating focused magnetic field pulses. A brain mapping is then generated by measuring responses of different motor and sensory functions to this stimulation. The key process in generating this mapping is the association of the 3-D positions and orientations of the TMS probe on the scalp to a 3-D brain reconstruction such as is feasible with a magnetic resonance image (MRI). We have developed a registration system which not only generates functional brain maps using such a device, but also provides real-time feedback to guide the technician in placing the probe at appropriate points on the head to achieve the desired map resolution. Functional areas we have mapped are the motor and visual cortex. Validation experiments focus on repeatability tests for mapping the same subjects several times. Applications of the technique include neuroanatomy research, surgical planning and guidance, treatment and disease monitoring, and therapeutic procedures. PMID:10646759

Ettinger, G J; Leventon, M E; Grimson, W E; Kikinis, R; Gugino, L; Cote, W; Sprung, L; Aglio, L; Shenton, M E; Potts, G; Hernandez, V L; Alexander, E

1998-06-01

113

Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models  

NASA Astrophysics Data System (ADS)

Transcranial magnetic stimulation (TMS) offers the possibility of non-invasive treatment of brain disorders in humans. Studies on animals can allow rapid progress of the research including exploring a variety of different treatment conditions. Numerical calculations using animal models are needed to help design suitable TMS coils for use in animal experiments, in particular, to estimate the electric field induced in animal brains. In this paper, we have implemented a high-resolution anatomical MRI-derived mouse model consisting of 50 tissue types to accurately calculate induced electric field in the mouse brain. Magnetic field measurements have been performed on the surface of the coil and compared with the calculations in order to validate the calculated magnetic and induced electric fields in the brain. Results show how the induced electric field is distributed in a mouse brain and allow investigation of how this could be improved for TMS studies using mice. The findings have important implications in further preclinical development of TMS for treatment of human diseases.

Crowther, L. J.; Hadimani, R. L.; Kanthasamy, A. G.; Jiles, D. C.

2014-05-01

114

Induction of central nervous system plasticity by repetitive transcranial magnetic stimulation to promote sensorimotor recovery in incomplete spinal cord injury  

PubMed Central

Cortical and spinal cord plasticity may be induced with non-invasive transcranial magnetic stimulation to encourage long term potentiation or depression of neuronal circuits. Such plasticity inducing stimulation provides an attractive approach to promote changes in sensorimotor circuits that have been degraded by spinal cord injury (SCI). If residual corticospinal circuits can be conditioned appropriately there should be the possibility that the changes are accompanied by functional recovery. This article reviews the attempts that have been made to restore sensorimotor function and to obtain functional benefits from the application of repetitive transcranial magnetic stimulation (rTMS) of the cortex following incomplete spinal cord injury. The confounding issues that arise with the application of rTMS, specifically in SCI, are enumerated. Finally, consideration is given to the potential for rTMS to be used in the restoration of bladder and bowel sphincter function and consequent functional recovery of the guarding reflex. PMID:24904326

Ellaway, Peter H.; Vásquez, Natalia; Craggs, Michael

2014-01-01

115

Combined functional magnetic resonance imaging and transcranial magnetic stimulation evidence of ipsilateral motor pathway with congenital brain disorder: A case report  

Microsoft Academic Search

Jang SH, Byun WM, Chang Y, Han BS, Ahn SH. Combined functional magnetic resonance imaging and transcranial magnetic stimulation evidence of ipsilateral motor pathway with congenital brain disorder: a case report. Arch Phys Med Rehabil 2001;82:1733-6. We present the case of 28-year-old man with schizencephaly who had mild left hemiparesis with mirror movement. Brain mapping using functional magnetic resonance imaging

Sung Ho Jang; Woo Mok Byun; Yongmin Chang; Bong Soo Han; Sang Ho Ahn

2001-01-01

116

Time-dependent effects of low-frequency repetitive transcranial magnetic stimulation of the supramarginal gyrus.  

PubMed

In this paper, we report our studies of the effects of stimulating the bilateral supramarginal gyrus (SMG) with low-frequency transcranial magnetic stimulation (rTMS) or short-term rTMS on brain excitability in humans. We analyzed the effects of various durations of stimulation on P300 latencies of the event-related potential (ERP). Magnetic pulses were delivered using a figure-eight flat coil. The intensity of rTMS was set to 80 % of the subject's motor threshold. In each round of rTMS, 100 magnetic pulses were applied over the scalp at frequencies of 1.00, 0.75, and 0.50 Hz. ERPs were measured prior to magnetic stimulation as a control. The effects of magnetic stimulation were then determined by measuring its effects on P300 latencies elicited by an odd-ball task. These latencies were measured before and 0, 5, 10, and 15 min after the magnetic stimulation. 1.00 Hz low-frequency rTMS of the left SMG decreased P300 latencies for approximately 10 min. In contrast, 0.50 Hz rTMS of the left SMG resulted in delayed P300 latencies for approximately 15 min. We furthermore found that 0.75 Hz rTMS of the left SMG and 1.00, 0.75 and 0.5 Hz rTMS of the right SMG did not affect P300 latencies. These results suggest that the duration of the effects of rTMS depend on the frequency of stimulation. PMID:23366649

Torii, T; Sato, A; Iwahashi, M; Itoh, Y; Iramina, K

2012-01-01

117

Stump nerve signals during transcranial magnetic motor cortex stimulation recorded in an amputee via longitudinal intrafascicular electrodes  

Microsoft Academic Search

Do central and peripheral motor pathways associated with an amputated limb retain at least some functions over periods of\\u000a years? This problem could be addressed by evaluating the response patterns of nerve signals from peripheral motor fibers during\\u000a transcranial magnetic stimulation (TMS) of corticospinal tracts. The aim of this study was to record for the first time TMS-related\\u000a responses from

P. M. Rossini; Jacopo Rigosa; Silvestro Micera; Giovanni Assenza; Luca Rossini; Florinda Ferreri

2011-01-01

118

Reliability of the input–output properties of the cortico-spinal pathway obtained from transcranial magnetic and electrical stimulation  

Microsoft Academic Search

The purpose of this experiment was to assess the test–retest reliability of input–output parameters of the cortico-spinal pathway derived from transcranial magnetic (TMS) and electrical (TES) stimulation at rest and during muscle contraction. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseous muscle of eight individuals on three separate days. The intensity of TMS at rest was varied

Timothy J Carroll; Stephan Riek; Richard G Carson

2001-01-01

119

Transcranial magnetic stimulation for the treatment of depression: feasibility and results under naturalistic conditions: a retrospective analysis  

Microsoft Academic Search

An increasing number of controlled studies strongly support an antidepressant effect of high-frequency repetitive transcranial\\u000a magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex. However, these data come from highly selected study\\u000a populations. Whether rTMS is a feasible therapeutic tool for the treatment of depression under naturalistic condition has\\u000a not yet been addressed. Here, we report results from 232 depressive

Elmar Frank; Peter Eichhammer; Julia Burger; Marc Zowe; Michael Landgrebe; Göran Hajak; Berthold Langguth

2011-01-01

120

Effects of attention on inhibitory and facilitatory phenomena elicited by paired-pulse transcranial magnetic stimulation in healthy subjects  

Microsoft Academic Search

We investigated whether human attentional processes influence the activity of intracortical inhibitory and excitatory circuits—short-interval\\u000a intracortical inhibition (SICI), long-interval intracortical inhibition (LICI), and the intracortical facilitation (ICF)—elicited\\u000a by paired-pulse transcranial magnetic stimulation (TMS) in healthy subjects. In eight healthy subjects we tested SICI, LICI\\u000a and ICF under different attention-demanding conditions: “relaxed”, “target hand” and “non-target hand”. To compare the effects

Antonella Conte; Daniele Belvisi; Ennio Iezzi; Francesco Mari; Maurizio Inghilleri; Alfredo Berardelli

2008-01-01

121

Suppression of EMG activity by subthreshold paired-pulse transcranial magnetic stimulation to the leg motor cortex  

Microsoft Academic Search

Cortical activity driving a voluntary muscle contraction is inhibited by very low-intensity transcranial magnetic stimulation\\u000a (TMS) and is reflected in the suppression of the average rectified EMG. This approach offers a method to test the contribution\\u000a of cortical neurons actively involved in a motor task, but requires a large number of stimuli (~100) to suitably depress the\\u000a average EMG. Here,

François D. Roy

2009-01-01

122

Effects of chronic levodopa and pergolide treatment on cortical excitability in patients with Parkinson's disease: a transcranial magnetic stimulation study  

Microsoft Academic Search

Objectives: Transcranial magnetic stimulation was used to assess the effects of chronic levodopa and pergolide treatment on motor cortex excitability in Parkinson disease (PD).Methods: Motor thresholds, intracortical inhibition and facilitation were studied at baseline and after 6 and 12 months of therapy in 10 PD patients and compared to 7 age-matched controls.Results: At baseline, there was significantly less intracortical inhibition

A. P Strafella; F Valzania; S. A Nassetti; A Tropeani; A Bisulli; M Santangelo; C. A Tassinari

2000-01-01

123

Preferential activation of different I waves by transcranial magnetic stimulation with a figure-of-eight-shaped coil  

Microsoft Academic Search

Transcranial magnetic stimulation (TMS) over the human primary motor cortex (M1) evokes motor responses in the contralateral\\u000a limb muscles. The latencies and amplitudes of those responses depend on the direction of induced current in the brain by the\\u000a stimuli (Mills et al. 1992, Werhahn et al. 1994). This observation suggests that different neural elements might be activated\\u000a by the differently

Katsuyuki Sakai; Yoshikazu Ugawa; Yasuo Terao; Ritsuko Hanajima; Toshiaki Furubayashi; Ichiro Kanazawa

1997-01-01

124

The right dorsolateral prefrontal cortex is essential in time reproduction: an investigation with repetitive transcranial magnetic stimulation  

Microsoft Academic Search

This study used repetitive transcranial magnetic stimulation (rTMS) to investigate the roles of the right dorsolateral prefrontal cortex (DLPFC) and supplementary motor area (SMA) in short (500 ms) and long (2 s) interval timing. The results were compared with rTMS over the leg area of motor cortex, an area not thought to be involved with time estimation. rTMS was delivered during one

Catherine R. G. Jones; Karin Rosenkranz; John C. Rothwell; Marjan Jahanshahi

2004-01-01

125

Repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex affects divided attention immediately after cessation of stimulation  

Microsoft Academic Search

Transcranial magnetic stimulation has evolved into a powerful neuroscientific tool allowing to interfere transiently with specific brain functions. In addition, repetitive TMS (rTMS) has long-term effects (e.g. on mood), probably mediated by neurochemical alterations. While long-term safety of rTMS with regard to cognitive functioning is well established from trials exploring its therapeutic efficacy, little is known on whether rTMS can

Michael Wagner; Tonia A. Rihs; Urs P. Mosimann; Hans U. Fisch; Thomas E. Schlaepfer

2006-01-01

126

Transcranial magnetic stimulation in treatment-resistant depressed patients: A double-blind, placebo-controlled trial  

Microsoft Academic Search

This 5-week, randomized, double-blind, placebo-controlled trial investigated the efficacy and tolerability of high frequency repetitive transcranial magnetic stimulation (rTMS) directed to the left prefrontal cortex in drug-resistant depressed patients. Fifty-four patients were randomly assigned to receive 10 daily applications of either real or sham rTMS. Subjects assigned to receive active stimulation were divided into two further subgroups according to the

David Rossini; Adelio Lucca; Raffaella Zanardi; Lorenzo Magri; Enrico Smeraldi

2005-01-01

127

High frequency transcranial magnetic stimulation mimics the effects of ECS in upregulating astroglial gene expression in the murine CNS.  

PubMed

The present study evaluates the consequences of high frequency (25 hz) trans-cranial magnetic stimulation on the expression of glial fibrillary acidic protein (GFAP) in the murine CNS. Trains of transcranial magnetic stimulation (1-30 trains at 25 Hz, 10 s duration) were delivered to mice via 5-cm diameter round coils. The stimulation produced stimulus-locked motor responses but did not elicit behavioral seizures. GFAP mRNA levels were evaluated 12, 24, 36, 48 h, 4 days, and 8 days following stimulation by in situ hybridization. Following multiple 25 Hz trains, there were dramatic increases in the levels of GFAP mRNA in the hippocampal dentate gyrus; more modest increases were observed in the cerebral cortex. The selective increases in GFAP mRNA in the dentate gyrus were similar to those observed following single electroconvulsive seizures (ECS). These results indicate that trans-cranial magnetic stimulation can be used to modulate astroglial gene expression, inducing the first stage of a reactive response that is similar to what occurs following nervous system injury. PMID:9073172

Fujiki, M; Steward, O

1997-03-01

128

Preserved Transcallosal Inhibition to Transcranial Magnetic Stimulation in Nondemented Elderly Patients with Leukoaraiosis  

PubMed Central

Structural corpus callosum (CC) changes in patients with leukoaraiosis (LA) are significantly associated with cognitive and motor impairment. The aim of this study is to investigate the transcallosal fibers functioning by means of transcranial magnetic stimulation (TMS) in elderly patients with LA. The resting motor threshold (rMT), the motor-evoked potentials (MEPs), and the controlateral (cSP) and ipsilateral silent periods (iSP) were determined using single-pulse TMS in 15 patients and 15 age-matched controls. The neuropsychological profile and the vascular burden at brain magnetic resonance imaging (MRI) were concomitantly explored. Patients reported abnormal scores at tests evaluating executive control functions. No significant difference was found in TMS measures of intra- and intercortical excitability. No CC lesion was evident at MRI. Transcallosal inhibitory mechanisms to TMS seem to be spared in LA patients, a finding which is in line with neuroimaging features and suggests a functional integrity of the CC despite the ischemic interruption of corticosubcortical loops implicated in cognition and behavior. The observed neurophysiological finding differs from that reported in degenerative dementia, even in the preclinical or early stage. In our group of patients, the pure extent of LA is more related to impairment of frontal lobe abilities rather than functional callosal changes. PMID:23984349

Bella, Rita; Giuffrida, Salvatore; Pennisi, Giovanni; Spampinato, Concetto; Giordano, Daniela; Malaguarnera, Giulia; Raggi, Alberto; Pennisi, Manuela

2013-01-01

129

Comparison of current distributions in electroconvulsive therapy and transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

We compared current density distributions in electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS) by numerical calculations. The model consisted of an air region and three types of tissues with different conductivities representing the brain, the skull, and the scalp. In the ECT model, electric currents were applied through electrodes with a voltage of 100 V. In the TMS model, a figure-eight coil (6 cm diameter per coil) was placed on the vertex of the head model. An alternating current with a peak intensity of 3.0 kA and a frequency of 4.2 kHz was applied to the coil. The maximum current densities inside the brain in ECT (bilateral electrode position) and TMS were 234 and 322 A/m2, respectively. The results indicate that magnetic stimulators can generate comparable current densities to ECT. While the skull significantly affected current distributions in ECT, TMS efficiently induced eddy currents in the brain. In addition, TMS is more beneficial than ECT because the localized current distribution reduces the risk of adverse side effects.

Sekino, Masaki; Ueno, Shoogo

2002-05-01

130

The influence of sulcus width on simulated electric fields induced by transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

Volume conduction models can help in acquiring knowledge about the distribution of the electric field induced by transcranial magnetic stimulation. One aspect of a detailed model is an accurate description of the cortical surface geometry. Since its estimation is difficult, it is important to know how accurate the geometry has to be represented. Previous studies only looked at the differences caused by neglecting the complete boundary between cerebrospinal fluid (CSF) and grey matter (Thielscher et al 2011 NeuroImage 54 234-43, Bijsterbosch et al 2012 Med. Biol. Eng. Comput. 50 671-81), or by resizing the whole brain (Wagner et al 2008 Exp. Brain Res. 186 539-50). However, due to the high conductive properties of the CSF, it can be expected that alterations in sulcus width can already have a significant effect on the distribution of the electric field. To answer this question, the sulcus width of a highly realistic head model, based on T1-, T2- and diffusion-weighted magnetic resonance images, was altered systematically. This study shows that alterations in the sulcus width do not cause large differences in the majority of the electric field values. However, considerable overestimation of sulcus width produces an overestimation of the calculated field strength, also at locations distant from the target location.

Janssen, A. M.; Rampersad, S. M.; Lucka, F.; Lanfer, B.; Lew, S.; Aydin, Ü.; Wolters, C. H.; Stegeman, D. F.; Oostendorp, T. F.

2013-07-01

131

The influence of sulcus width on simulated electric fields induced by transcranial magnetic stimulation  

PubMed Central

Volume conduction models can help in acquiring knowledge about the distribution of the electric field induced by transcranial magnetic stimulation (TMS). One aspect of a detailed model is an accurate description of the cortical surface geometry. Since its estimation is difficult, it is important to know how accurate the geometry has to be represented. Previous studies only looked at the differences caused by neglecting the complete boundary between the CSF and GM (Thielscher et al. 2011; Bijsterbosch et al. 2012), or by resizing the whole brain (Wagner et al. 2008). However, due to the high conductive properties of the CSF, it can be expected that alterations in sulcus width can already have a significant effect on the distribution of the electric field. To answer this question, the sulcus width of a highly realistic head model, based on T1-, T2- and diffusion-weighted magnetic resonance images (MRI), was altered systematically. This study shows that alterations in the sulcus width do not cause large differences in the majority of the electric field values. However, considerable overestimation of sulcus width produces an overestimation of the calculated field strength, also at locations distant from the target location. PMID:23787706

Janssen, A M; Rampersad, S M; Lucka, F; Lanfer, B; Lew, S; Aydin, Ü; Wolters, C H; Stegeman, D F; Oostendorp, T F

2013-01-01

132

The Neuroprotection of Repetitive Transcranial Magnetic Stimulation Pre-treatment in Vascular Dementia Rats.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that could interfere cortical excitability though brief electric currents induced by alternating magnetic fields from the inductive coil. Currently, it has been applied in many fields of basic and clinical neuro-research. The aims of the present study are to investigate the effect of rTMS pre-treatment on cognitive function in vascular dementia (VaD) rats and further explore the molecular mechanism of rTMS neuroprotection on VaD. We found that rTMS pre-treated VaD rats showed significantly better memory and learning abilities in Morris water maze test compared to the untreated group. Moreover, the mRNA and protein expression levels of BDNF, TrkB, and SYN were significantly higher in the rTMS pre-treated group, indicating that rTMS pre-treatment has neuroprotective effect for VaD, which may have resulted from the increased level of BDNF, TrkB, and SYN in the hippocampal CA1 area. PMID:25585610

Wang, Fei; Chang, Guang-Ming; Yu, Qian; Geng, Xin

2015-05-01

133

Transcranial magnetic stimulation for investigating causal brain-behavioral relationships and their time course.  

PubMed

Transcranial magnetic stimulation (TMS) is a safe, non-invasive brain stimulation technique that uses a strong electromagnet in order to temporarily disrupt information processing in a brain region, generating a short-lived "virtual lesion." Stimulation that interferes with task performance indicates that the affected brain region is necessary to perform the task normally. In other words, unlike neuroimaging methods such as functional magnetic resonance imaging (fMRI) that indicate correlations between brain and behavior, TMS can be used to demonstrate causal brain-behavior relations. Furthermore, by varying the duration and onset of the virtual lesion, TMS can also reveal the time course of normal processing. As a result, TMS has become an important tool in cognitive neuroscience. Advantages of the technique over lesion-deficit studies include better spatial-temporal precision of the disruption effect, the ability to use participants as their own control subjects, and the accessibility of participants. Limitations include concurrent auditory and somatosensory stimulation that may influence task performance, limited access to structures more than a few centimeters from the surface of the scalp, and the relatively large space of free parameters that need to be optimized in order for the experiment to work. Experimental designs that give careful consideration to appropriate control conditions help to address these concerns. This article illustrates these issues with TMS results that investigate the spatial and temporal contributions of the left supramarginal gyrus (SMG) to reading. PMID:25079670

Sliwinska, Magdalena W; Vitello, Sylvia; Devlin, Joseph T

2014-01-01

134

A measure of acoustic noise generated from transcranial magnetic stimulation coils.  

PubMed

The intensity of sound emanating from the discharge of magnetic coils used in repetitive transcranial magnetic stimulation (rTMS) can potentially cause acoustic trauma. Per Occupational Safety and Health Administration (OSHA) standards for safety of noise exposure, hearing protection is recommended beyond restricted levels of noise and time limits. We measured the sound pressure levels (SPLs) from four rTMS coils with the goal of assessing if the acoustic artifact levels are of sufficient amplitude to warrant protection from acoustic trauma per OSHA standards. We studied the SPLs at two frequencies (5 and 10 Hz), three machine outputs (MO) (60, 80 and 100%), and two distances from the coil (5 and 10 cm). We found that the SPLs were louder at closer proximity from the coil and directly dependent on the MO. We also found that in all studied conditions, SPLs were lower than the OSHA permissible thresholds for short (<15 min) acoustic exposure, but at extremes of use, may generate sufficient noise to warrant ear protection with prolonged (>8 h) exposure. PMID:24582370

Dhamne, Sameer C; Kothare, Raveena S; Yu, Camilla; Hsieh, Tsung-Hsun; Anastasio, Elana M; Oberman, Lindsay; Pascual-Leone, Alvaro; Rotenberg, Alexander

2014-01-01

135

[Design of a half solenoid coil for optimization of magnetic focusing in trans-cranial magnetic stimulation].  

PubMed

Trans-cranial magnetic stimulation (TMS) is the process that excitable human brain tissue is activated with the electric field induced from a changing magnetic field. Magnetic focusing characteristic is one of the most important technical considerations of coil design in TMS. In this paper, a half solenoid coil was proposed to be used in TMS and the magnitude profile of the induced electric fields in different depth was studied based on the induced electric field theory of magnetic stimulating coil. The magnitude profile of the induced electric fields produced by half solenoid coils was compared with that of butterfly-shaped coils. The result shows that half solenoid coils retain the good focusing characteristics of the main lobe of the butterfly-shaped coils. At the same time side effect of the side lobes on notargeted tissue is mitigated, which would otherwise lead to undesirable stimulation. Hence magnetic focusing is optimized, which is expected to give a more accurate delivery of the focal point for more effective stimulation. PMID:17899772

Hu, Weiping; Wang, Xiuxin; Yang, Yongxu; Liang, Dongdong; Zhao, Fangwei

2007-08-01

136

Treatment envelope evaluation in transcranial magnetic resonance-guided focused ultrasound utilizing 3D MR thermometry  

PubMed Central

Background Current clinical targets for transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) are all located close to the geometric center of the skull convexity, which minimizes challenges related to focusing the ultrasound through the skull bone. Non-central targets will have to be reached to treat a wider variety of neurological disorders and solid tumors. Treatment envelope studies utilizing two-dimensional (2D) magnetic resonance (MR) thermometry have previously been performed to determine the regions in which therapeutic levels of FUS can currently be delivered. Since 2D MR thermometry was used, very limited information about unintended heating in near-field tissue/bone interfaces could be deduced. Methods In this paper, we present a proof-of-concept treatment envelope study with three-dimensional (3D) MR thermometry monitoring of FUS heatings performed in a phantom and a lamb model. While the moderate-sized transducer used was not designed for transcranial geometries, the 3D temperature maps enable monitoring of the entire sonication field of view, including both the focal spot and near-field tissue/bone interfaces, for full characterization of all heating that may occur. 3D MR thermometry is achieved by a combination of k-space subsampling and a previously described temporally constrained reconstruction method. Results We present two different types of treatment envelopes. The first is based only on the focal spot heating—the type that can be derived from 2D MR thermometry. The second type is based on the relative near-field heating and is calculated as the ratio between the focal spot heating and the near-field heating. This utilizes the full 3D MR thermometry data achieved in this study. Conclusions It is shown that 3D MR thermometry can be used to improve the safety assessment in treatment envelope evaluations. Using a non-optimal transducer, it is shown that some regions where therapeutic levels of FUS can be delivered, as suggested by the first type of envelope, are not necessarily safely treated due to the amount of unintended near-field heating occurring. The results presented in this study highlight the need for 3D MR thermometry in tcMRgFUS. PMID:25343028

2014-01-01

137

Cerebellar Transcranial Magnetic Stimulation: The Role of Coil Geometry and Tissue Depth?  

PubMed Central

Background While transcranial magnetic stimulation (TMS) coil geometry has important effects on the evoked magnetic field, no study has systematically examined how different coil designs affect the effectiveness of cerebellar stimulation. Hypothesis The depth of the cerebellar targets will limit efficiency. Angled coils designed to stimulate deeper tissue are more effective in eliciting cerebellar stimulation. Methods Experiment 1 examined basic input–output properties of the figure-of-eight, batwing and double-cone coils, assessed with stimulation of motor cortex. Experiment 2 assessed the ability of each coil to activate cerebellum, using cerebellar-brain inhibition (CBI). Experiment 3 mapped distances from the scalp to cerebellar and motor cortical targets in a sample of 100 subjects' structural magnetic resonance images. Results Experiment 1 showed batwing and double-cone coils have significantly lower resting motor thresholds, and recruitment curves with steeper slopes than the figure-of-eight coil. Experiment 2 showed the double-cone coil was the most efficient for eliciting CBI. The batwing coil induced CBI only at higher stimulus intensities. The figure-of-eight coil did not elicit reliable CBI. Experiment 3 confirmed that cerebellar tissue is significantly deeper than primary motor cortex tissue, and we provide a map of scalp-to-target distances. Conclusions The double-cone and batwing coils designed to stimulate deeper tissue can effectively stimulate cerebellar targets. The double-cone coil was found to be most effective. The depth map provides a guide to the accessible regions of the cerebellar volume. These results can guide coil selection and stimulation parameters when designing cerebellar TMS studies. PMID:24924734

Hardwick, Robert M.; Lesage, Elise; Miall, R. Chris

2014-01-01

138

Interdisciplinary Approaches of Transcranial Magnetic Stimulation Applied to a Respiratory Neuronal Circuitry Model  

PubMed Central

Respiratory related diseases associated with the neuronal control of breathing represent life-threatening issues and to date, no effective therapeutics are available to enhance the impaired function. The aim of this study was to determine whether a preclinical respiratory model could be used for further studies to develop a non-invasive therapeutic tool applied to rat diaphragmatic neuronal circuitry. Transcranial magnetic stimulation (TMS) was performed on adult male Sprague-Dawley rats using a human figure-of-eight coil. The largest diaphragmatic motor evoked potentials (MEPdia) were recorded when the center of the coil was positioned 6 mm caudal from Bregma, involving a stimulation of respiratory supraspinal pathways. Magnetic shielding of the coil with mu metal reduced magnetic field intensities and improved focality with increased motor threshold and lower amplitude recruitment curve. Moreover, transynaptic neuroanatomical tracing with pseudorabies virus (applied to the diaphragm) suggest that connections exist between the motor cortex, the periaqueductal grey cell regions, several brainstem neurons and spinal phrenic motoneurons (distributed in the C3-4 spinal cord). These results reveal the anatomical substrate through which supraspinal stimulation can convey descending action potential volleys to the spinal motoneurons (directly or indirectly). We conclude that MEPdia following a single pulse of TMS can be successfully recorded in the rat and may be used in the assessment of respiratory supraspinal plasticity. Supraspinal non-invasive stimulations aimed to neuromodulate respiratory circuitry will enable new avenues of research into neuroplasticity and the development of therapies for respiratory dysfunction associated with neural injury and disease (e.g. spinal cord injury, amyotrophic lateral sclerosis). PMID:25406091

Vinit, Stéphane; Keomani, Emilie; Deramaudt, Thérèse B.; Spruance, Victoria M.; Bezdudnaya, Tatiana; Lane, Michael A.

2014-01-01

139

Sensorimotor Plasticity after Music-Supported Therapy in Chronic Stroke Patients Revealed by Transcranial Magnetic Stimulation  

PubMed Central

Background Several recently developed therapies targeting motor disabilities in stroke sufferers have shown to be more effective than standard neurorehabilitation approaches. In this context, several basic studies demonstrated that music training produces rapid neuroplastic changes in motor-related brain areas. Music-supported therapy has been recently developed as a new motor rehabilitation intervention. Methods and Results In order to explore the plasticity effects of music-supported therapy, this therapeutic intervention was applied to twenty chronic stroke patients. Before and after the music-supported therapy, transcranial magnetic stimulation was applied for the assessment of excitability changes in the motor cortex and a 3D movement analyzer was used for the assessment of motor performance parameters such as velocity, acceleration and smoothness in a set of diadochokinetic movement tasks. Our results suggest that the music-supported therapy produces changes in cortical plasticity leading the improvement of the subjects' motor performance. Conclusion Our findings represent the first evidence of the neurophysiological changes induced by this therapy in chronic stroke patients, and their link with the amelioration of motor performance. Further studies are needed to confirm our observations. PMID:23613966

Amengual, Julià L.; Rojo, Nuria; Veciana de las Heras, Misericordia; Marco-Pallarés, Josep; Grau-Sánchez, Jennifer; Schneider, Sabine; Vaquero, Lucía; Juncadella, Montserrat; Montero, Jordi; Mohammadi, Bahram; Rubio, Francisco; Rueda, Nohora; Duarte, Esther; Grau, Carles; Altenmüller, Eckart; Münte, Thomas F.; Rodríguez-Fornells, Antoni

2013-01-01

140

Transcranial magnetic stimulation over human secondary somatosensory cortex disrupts perception of pain intensity.  

PubMed

Pain is a complex sensory experience resulting from the activity of a network of brain regions. However, the functional contribution of individual regions in this network remains poorly understood. We delivered single-pulse transcranial magnetic stimulation (TMS) to the contralateral primary somatosensory cortex (S1), secondary somatosensory cortex (S2) and vertex (control site) 120 msec after selective stimulation of nociceptive afferents using neodymium:yttrium-aluminium-perovskite (Nd:YAP) laser pulses causing painful sensations. Participants were required to judge either the intensity (medium/high) or the spatial location (proximal/distal) of the stimulus in a two-alternative forced choice paradigm. When TMS pulses were delivered over S2, participants' ability to judge pain intensity was disrupted, as compared to S1 and vertex (control) stimulation. Signal-detection analysis demonstrated a loss of sensitivity to stimulation intensity, rather than a shift in perceived pain level or response bias. We did not find any effect of TMS on the ability to localise nociceptive stimuli on the skin. The novel finding that TMS over S2 can disrupt perception of pain intensity suggests a causal role for S2 in encoding of pain intensity. PMID:23290634

Lockwood, Patricia L; Iannetti, Gian Domenico; Haggard, Patrick

2013-09-01

141

The Effects of Lateral Prefrontal Transcranial Magnetic Stimulation on Item Memory Encoding  

PubMed Central

Previous neuroimaging research has established that the left ventrolateral prefrontal cortex (VLPFC) is involved in long-term memory (LTM) encoding for individual items. Dorsolateral prefrontal cortex (DLPFC) is implicated less frequently, and one theory that has gained support to explain this discrepancy is that DLPFC is involved in forming item-item relational but not item LTM. Given that neuroimaging results are correlational, complimentary methods such as repetitive Transcranial Magnetic Stimulation (TMS) have been used to test causal hypotheses generated from imaging data. Most TMS studies of LTM encoding have found that disruption of lateral PFC activity impairs subsequent memory. However these studies have lacked methods to precisely localize and directly compare TMS effects from frontal subregions implicated by the neuroimaging literature. Here, we target specific subregions of lateral PFC with TMS to test the prediction from the item/relational framework that temporary disruption of VLPFC during encoding will impair subsequent memory whereas TMS to DLPFC during item encoding will not. Frontal TMS was administered prior to a LTM encoding task in which participants were presented with a list of individual nouns and asked to judge whether each noun was concrete or abstract. After a 40 minute delay period, item recognition memory was tested. Results indicate that VLPFC and DLPFC TMS have differential effects on subsequent item memory. VLPFC TMS reliably disrupted subsequent item memory whereas DLPFC TMS led to numerical enhancement in item memory, relative to TMS to a control region. PMID:24316198

Blumenfeld, Robert S.; Lee, Taraz; D’Esposito, Mark

2015-01-01

142

Neural summation in human motor cortex by subthreshold transcranial magnetic stimulations.  

PubMed

Integration of diverse synaptic inputs is a basic neuronal operation that relies on many neurocomputational principles, one of which is neural summation. However, we lack empirical understanding of neuronal summation in the human brains in vivo. Here, we explored the effect of neural summation on the motor cortex using two subthreshold pulses of transcranial magnetic stimulation (TMS), each with intensities ranging from 60 to 95% of the resting motor threshold (RMT) and interstimulus interval (ISI) varying from 1 to 25 ms. We found that two subthreshold TMS pulses can produce suprathreshold motor response when ISIs were less than 10 ms, most prominent at 1, 1.5 and 3 ms. This facilitatory, above-threshold response was evident when the intensity of the subthreshold pulses was above 80% of RMT but was absent as the intensity was 70% or below. Modeling of the summation data across intensity suggested that they followed an exponential function with excellent model fitting. Understanding the constraints for inducing summation of subthreshold stimulations to generate above-threshold response may have implications in modeling neural operations and potential clinical applications. PMID:25399245

Du, Xiaoming; Choa, Fow-Sen; Summerfelt, Ann; Tagamets, Malle A; Rowland, Laura M; Kochunov, Peter; Shepard, Paul; Hong, L Elliot

2015-02-01

143

The effects of lateral prefrontal transcranial magnetic stimulation on item memory encoding.  

PubMed

Previous neuroimaging research has established that the left ventrolateral prefrontal cortex (VLPFC) is involved in long-term memory (LTM) encoding for individual items. Dorsolateral prefrontal cortex (DLPFC) is implicated less frequently, and one theory that has gained support to explain this discrepancy is that DLPFC is involved in forming item-item relational but not item LTM. Given that neuroimaging results are correlational, complimentary methods such as repetitive transcranial magnetic stimulation (TMS) have been used to test causal hypotheses generated from imaging data. Most TMS studies of LTM encoding have found that disruption of lateral PFC activity impairs subsequent memory. However these studies have lacked methods to precisely localize and directly compare TMS effects from frontal subregions implicated by the neuroimaging literature. Here, we target specific subregions of lateral PFC with TMS to test the prediction from the item/relational framework that temporary disruption of VLPFC during encoding will impair subsequent memory whereas TMS to DLPFC during item encoding will not. Frontal TMS was administered prior to a LTM encoding task in which participants were presented with a list of individual nouns and asked to judge whether each noun was concrete or abstract. After a 40 min delay period, item recognition memory was tested. Results indicate that VLPFC and DLPFC TMS have differential effects on subsequent item memory. VLPFC TMS reliably disrupted subsequent item memory whereas DLPFC TMS led to numerical enhancement in item memory, relative to TMS to a control region. PMID:24316198

Blumenfeld, Robert S; Lee, Taraz G; D'Esposito, Mark

2014-01-01

144

Effects of repetitive transcranial magnetic stimulation on synaptic plasticity and apoptosis in vascular dementia rats.  

PubMed

This study aims to determine whether low-frequency repetitive transcranial magnetic stimulation (rTMS) protects pyramidal cells from apoptosis and promotes hippocampal synaptic plasticity in a vascular dementia (VaD) rat model. Following establishment of a VaD rat model using two-vessel occlusion (2VO), learning and memory were evaluated via the Morris Water Maze (MWM), hippocampal CA1 neuron ultrastructure was examined via electron microscopy, and hippocampal synaptic plasticity was assessed by long-term potentiation (LTP). Western blot was used to detect the expression of N-methyl-d-aspartic acid receptor 1 (NMDAR1), Bcl-2, and Bax. Compared with VaD group, rats treated with low-frequency rTMS had reduced-escape latencies, increased swimming time in the target quadrant (P<0.05), and significantly less synaptic structure damage. LTP at hippocampal CA3-CA1 synapses was enhanced (P<0.05). Low-frequency rTMS significantly up-regulated NMDAR1 and Bcl-2 expression and down-regulated Bax expression. Low-frequency rTMS improves learning and memory, protects the synapse, and increases synaptic plasticity in VaD model rats. Increased Bcl-2 expression and reduced Bax expression may be a novel protective mechanism of low-frequency rTMS treatment for VaD. PMID:25541037

Yang, Hui-Yun; Liu, Yang; Xie, Jia-Cun; Liu, Nan-Nan; Tian, Xin

2015-03-15

145

Combining near-infrared spectroscopy with electroencephalography and repetitive transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

The objective of the study was to assess the usability of a near-infrared spectroscopy (NIRS) device in multimodal measurements. We combined NIRS with electroencephalography (EEG) to record hemodynamic responses and evoked potentials simultaneously, and with transcranial magnetic stimulation (TMS) to investigate hemodynamic responses to repetitive TMS (rTMS). Hemodynamic responses and visual evoked potentials (VEPs) to 3, 6, and 12 s stimuli consisting of pattern-reversing checkerboards were successfully recorded in the NIRS/EEG measurement, and ipsi- and contralateral hemodynamic responses to 0.5, 1, and 2 Hz rTMS in the NIRS/TMS measurement. In the NIRS/EEG measurements, the amplitudes of the hemodynamic responses increased from 3- to 6-s stimulus, but not from 6- to 12-s stimulus, and the VEPs showed peaks N75, P100, and N135. In the NIRS/TMS measurements, the 2-Hz stimulus produced the strongest hemodynamic responses compared to the 0.5- and 1-Hz stimuli. In two subjects oxyhemoglobin concentration decreased and in one increased as a consequence of the 2-Hz rTMS. To locate the origin of the measured NIRS responses, methods have to be developed to investigate TMS-induced scalp muscle contractions. In the future, multimodal measurements may prove useful in monitoring or treating diseases such as stroke or Alzheimer's disease.

Näsi, Tiina; Kotilahti, Kalle; Mäki, Hanna; Nissilä, Ilkka; Meriläinen, Pekka

2009-07-01

146

Repetitive transcranial magnetic stimulation enhances BDNF-TrkB signaling in both brain and lymphocyte.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) induces neuronal long-term potentiation or depression. Although brain-derived neurotrophic factor (BDNF) and its cognate tyrosine receptor kinase B (TrkB) contribute to the effects of rTMS, their precise role and underlying mechanism remain poorly understood. Here we show that daily 5 Hz rTMS for 5 d improves BDNF-TrkB signaling in rats by increasing the affinity of BDNF for TrkB, which results in higher tyrosine-phosphorylated TrkB, increased recruitment of PLC-?1 and shc/N-shc to TrkB, and heightened downstream ERK2 and PI-3K activities in prefrontal cortex and in lymphocytes. The elevated BDNF-TrkB signaling is accompanied by an increased association between the activated TrkB and NMDA receptor (NMDAR). In normal human subjects, 5 d rTMS to motor cortex decreased resting motor threshold, which correlates with heightened BDNF-TrkB signaling and intensified TrkB-NMDAR association in lymphocytes. These findings suggest that rTMS to cortex facilitates BDNF-TrkB-NMDAR functioning in both cortex and lymphocytes. PMID:21795553

Wang, Hoau-Yan; Crupi, Domenica; Liu, Jingjing; Stucky, Andres; Cruciata, Giuseppe; Di Rocco, Alessandro; Friedman, Eitan; Quartarone, Angelo; Ghilardi, M Felice

2011-07-27

147

Probing feedforward and feedback contributions to awareness with visual masking and transcranial magnetic stimulation  

PubMed Central

A number of influential theories posit that visual awareness relies not only on the initial, stimulus-driven (i.e., feedforward) sweep of activation but also on recurrent feedback activity within and between brain regions. These theories of awareness draw heavily on data from masking paradigms in which visibility of one stimulus is reduced due to the presence of another stimulus. More recently transcranial magnetic stimulation (TMS) has been used to study the temporal dynamics of visual awareness. TMS over occipital cortex affects performance on visual tasks at distinct time points and in a manner that is comparable to visual masking. We draw parallels between these two methods and examine evidence for the neural mechanisms by which visual masking and TMS suppress stimulus visibility. Specifically, both methods have been proposed to affect feedforward as well as feedback signals when applied at distinct time windows relative to stimulus onset and as a result modify visual awareness. Most recent empirical evidence, moreover, suggests that while visual masking and TMS impact stimulus visibility comparably, the processes these methods affect may not be as similar as previously thought. In addition to reviewing both masking and TMS studies that examine feedforward and feedback processes in vision, we raise questions to guide future studies and further probe the necessary conditions for visual awareness. PMID:25374548

Tapia, Evelina; Beck, Diane M.

2014-01-01

148

Parietal influence on temporal encoding indexed by simultaneous transcranial magnetic stimulation and electroencephalography.  

PubMed

Previous studies have suggested that contingent negative variation (CNV), as recorded by electroencaphalography (EEG), may serve as an index of temporal encoding. The interpretation of these studies is complicated by the fact that, in a majority of studies, the CNV signal was obtained at a time when subjects were not only registering stimulus duration but also making decisions and preparing to act. Previously, we demonstrated that repetitive transcranial magnetic stimulation (rTMS) of the right supramarginal gyrus (rSMG) in humans lengthened the perceived duration of a visual stimulus (Wiener et al., 2010a), suggesting the rSMG is involved in basic encoding processes. Here, we report a replication of this effect with simultaneous EEG recordings during the encoding of stimulus duration. Stimulation of the rSMG led to an increase in perceived duration and the amplitude of N1 and CNV components recorded from frontocentral sites. Furthermore, the size of the CNV amplitude, but not N1, positively correlated with the size of the rTMS effect but negatively correlated with bias (the baseline tendency to report a comparison stimulus as shorter), suggesting that the CNV indexes stimulus duration. These results suggest that a feedforward mechanism from parietal to prefrontal regions mediates temporal encoding and demonstrate a dissociation between early and late phases of encoding processes. PMID:22933807

Wiener, Martin; Kliot, Dasha; Turkeltaub, Peter E; Hamilton, Roy H; Wolk, David A; Coslett, H Branch

2012-08-29

149

Disruptions to human speed perception induced by motion adaptation and transcranial magnetic stimulation.  

PubMed

To investigate the underlying nature of the effects of transcranial magnetic stimulation (TMS) on speed perception, we applied repetitive TMS (rTMS) to human V5/MT+ following adaptation to either fast- (20 deg/s) or slow (4 deg/s)-moving grating stimuli. The adapting stimuli induced changes in the perceived speed of a standard reference stimulus moving at 10 deg/s. In the absence of rTMS, adaptation to the slower stimulus led to an increase in perceived speed of the reference, whilst adaptation to the faster stimulus produced a reduction in perceived speed. These induced changes in speed perception can be modelled by a ratio-taking operation of the outputs of two temporally tuned mechanisms that decay exponentially over time. When rTMS was applied to V5/MT+ following adaptation, the perceived speed of the reference stimulus was reduced, irrespective of whether adaptation had been to the faster- or slower-moving stimulus. The fact that rTMS after adaptation always reduces perceived speed, independent of which temporal mechanism has undergone adaptation, suggests that rTMS does not selectively facilitate activity of adapted neurons but instead leads to suppression of neural function. The results highlight the fact that potentially different effects are generated by TMS on adapted neuronal populations depending upon whether or not they are responding to visual stimuli. PMID:19912329

Burton, M P; McKeefry, D J; Barrett, B T; Vakrou, C; Morland, A B

2009-11-01

150

Transcranial magnetic stimulation modulates the brain's intrinsic activity in a frequency-dependent manner.  

PubMed

Intrinsic activity in the brain is organized into networks. Although constrained by their anatomical connections, functional correlations between nodes of these networks reorganize dynamically. Dynamic organization implies that couplings between network nodes can be reconfigured to support processing demands. To explore such reconfigurations, we combined repetitive transcranial magnetic stimulation (rTMS) and functional connectivity MRI (fcMRI) to modulate cortical activity in one node of the default network, and assessed the effect of this upon functional correlations throughout the network. Two different frequencies of rTMS to the same default network node (the left posterior inferior parietal lobule, lpIPL) induced two topographically distinct changes in functional connectivity. High-frequency rTMS to lpIPL decreased functional correlations between cortical default network nodes, but not between these nodes and the hippocampal formation. In contrast, low frequency rTMS to lpIPL did not alter connectivity between cortical default network nodes, but increased functional correlations between lpIPL and the hippocampal formation. These results suggest that the default network is composed of (at least) two subsystems. More broadly, the finding that two rTMS stimulation regimens to the same default network node have distinct effects reveals that this node is embedded within a network that possesses multiple, functionally distinct relationships among its distributed partners. PMID:22160708

Eldaief, Mark C; Halko, Mark A; Buckner, Randy L; Pascual-Leone, Alvaro

2011-12-27

151

Neural Correlates of the Antinociceptive Effects of Repetitive Transcranial Magnetic Stimulation on Central Pain After Stroke  

PubMed Central

Background Repetitive transcranial magnetic stimulation (rTMS) modulates central neuropathic pain in some patients after stroke, but the mechanisms of action are uncertain. Objective The authors used diffusion tensor imaging (DTI) and functional MRI (fMRI) to evaluate the integrity of the thalamocortical tract (TCT) and the activation pattern of the pain network in 22 patients with poststroke central pain. Methods Each patient underwent daily 10-Hz rTMS sessions for 1000 pulses on 5 consecutive days over the hotspot for the first dorsal interosseus muscle. Pain severity was monitored using the Visual Analogue Scale (VAS). Mood was assessed by the Hamilton Depression Rating Scale. Results Clinical data from all participants along with the DTI and fMRI findings from 10 patients were analyzed. VAS scores decreased significantly, if modestly, following administration of rTMS in 14 responders, which lasted for 2 weeks after the intervention. Regression analysis showed a significant correlation between less initial depression and higher antalgic effect of rTMS. Integrity of the superior TCT in the ipsilesional hemisphere showed significant correlation with change of VAS score after rTMS. fMRI showed significantly decreased activity in the secondary somatosensory cortex, insula, prefrontal cortex, and putamen in rTMS responders, whereas no change was noted in nonresponders. Conclusion Mood may affect the modest antinociceptive effects of rTMS that we found, which may be mediated by the superior TCT through modulation of a distributed pain network. PMID:21980153

Ohn, Suk Hoon; Chang, Won Hyuk; Park, Chang-hyun; Kim, Sung Tae; Lee, Jung Il; Pascual-Leone, Alvaro; Kim, Yun-Hee

2013-01-01

152

Frontal eye field involvement in sustaining visual attention: Evidence from transcranial magnetic stimulation.  

PubMed

The frontal eye field (FEF), particularly the right FEF, is broadly implicated in top-down control of transient acts of attention, but less is known about its involvement in sustained attention. Although neuroimaging studies of sustained attention tasks commonly find FEF activation, it is unclear how this region contributes to moment-to-moment fluctuations in sustained performance. We sought to determine if the FEF plays a critical role in sustained attention, and if that role differs between periods of worse performance (out-of-the-zone) and periods of better performance (in-the-zone). We used offline 1Hz repetitive transcranial magnetic stimulation (TMS) to temporarily attenuate either right or left FEF excitability while participants performed a go/no-go sustained attention task (the gradual onset continuous performance task). The results demonstrate that following TMS to the right FEF, sustained attention during in-the-zone periods significantly worsened both in terms of lower accuracy and increased reaction time variability. In contrast, applying TMS to the left FEF did not significantly affect accuracy or variability. These results demonstrate that the right FEF plays a crucial role in supporting optimal sustained attention. PMID:25655445

Esterman, Michael; Liu, Guanyu; Okabe, Hidefusa; Reagan, Andrew; Thai, Michelle; DeGutis, Joe

2015-05-01

153

Potentiation of quantitative electroencephalograms following prefrontal repetitive transcranial magnetic stimulation in patients with major depression.  

PubMed

The long-lasting effects of repetitive transcranial magnetic stimulation (rTMS) on electroencephalogram (EEG) activity are not clear. We aimed to investigate the cumulative rTMS effects on EEG and clinical outcomes in patients with major depression. Twenty-five patients with medication-resistant depression underwent 10 daily rTMS sessions over the left dorsolateral prefrontal cortex. We measured resting EEG and spectrum-power before and after the rTMS course. Clinical efficacy was evaluated with the Hamilton's Depression Rating Scale (HAM-D) and Wisconsin Card Sorting Test (WCST). In an ANOVA model, including all prefrontal electrodes, post hoc analyses revealed significant time effects on the theta (F1,24 = 7.89, P = 0.010; +43%), delta (F1,24 = 6.58, P = 0.017; +26%), and alpha (F1,24 = 4.64, P = 0.042; 31%) bands without site specificity. Clinical correlations were observed between F4 alpha power increases and improvements in HAM-D retardation, F3 alpha power increases and improvements of the absolute changes in perseveration and error number on the WCST, and C3 and C4 theta power increases and improvements of the percent change in perseveration and error number on the WCST following rTMS. Consecutive prefrontal rTMS could induce long-lasting EEG potentiations beyond the aftereffects, resulting in improved cognitive and depressive symptoms. PMID:23827366

Noda, Yoshihiro; Nakamura, Motoaki; Saeki, Takashi; Inoue, Misa; Iwanari, Hideo; Kasai, Kiyoto

2013-01-01

154

Timecourse of mirror and counter-mirror effects measured with transcranial magnetic stimulation  

PubMed Central

The human mirror system has been the subject of much research over the past two decades, but little is known about the timecourse of mirror responses. In addition, it is unclear whether mirror and counter-mirror effects follow the same timecourse. We used single-pulse transcranial magnetic stimulation to investigate the timecourse of mirror and counter-mirror responses in the human brain. Experiment 1 demonstrated that mirror responses can be measured from around 200 ms after observed action onset. Experiment 2 demonstrated significant effects of counter-mirror sensorimotor training at all timepoints at which a mirror response was found in Experiment 1 (i.e. from 200 ms onward), indicating that mirror and counter-mirror responses follow the same timecourse. By suggesting similarly direct routes for mirror and counter-mirror responses, these results support the associative account of mirror neuron origins whereby mirror responses arise as a result of correlated sensorimotor experience during development. More generally, they contribute to theorizing regarding mirror neuron function by providing some constraints on how quickly mirror responses can influence social cognition. PMID:23709352

Cavallo, Andrea; Heyes, Cecilia; Becchio, Cristina; Bird, Geoffrey

2014-01-01

155

Positive predictors for antidepressive response to prefrontal repetitive transcranial magnetic stimulation (rTMS).  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is a brain stimulation technique which had recently been investigated as a putative antidepressant intervention. However, there is little agreement about clinically useful predictors of rTMS outcome. Therefore, the objective of the present study was to determine whether specific biographical, clinical, and psychopathological parameters are associated with the antidepressant response to rTMS in a large sample of 70 depressive patients. We performed a logistic regression analysis in 70 patients with major depressive disorder treated with rTMS of the left dorsolateral prefrontal cortex testing the predictive value of various domains of the depression syndrome as well as the variables episode duration, degree of treatment resistance, and CORE criteria. Response was defined as a 50% reduction of the initial Hamilton score (HAMD). After two weeks of treatment, 21% of the patients showed a response to rTMS. The binary logistic regression model correctly assigned 86.7% of the responders and 96.4% of the non-responders to their final response group. In the model, a high level of sleep disturbances was a significant predictor for treatment response to rTMS. Also, a low score of treatment resistance and a short duration of episode were positive predictors. These findings provide new evidence that especially pronounced sleep disturbances may be a significant clinical predictor of a response to rTMS. Prospective rTMS studies are necessary to validate the predictive value of the derived model. PMID:16554071

Brakemeier, Eva-Lotta; Luborzewski, Alexander; Danker-Hopfe, Heidi; Kathmann, Norbert; Bajbouj, Malek

2007-08-01

156

Determination of motor threshold using visual observation overestimates transcranial magnetic stimulation dosage: Safety implications  

PubMed Central

Objective While the standard has been to define motor threshold (MT) using EMG to measure motor cortex response to transcranial magnetic stimulation (TMS), another method of determining MT using visual observation of muscle twitch (OM-MT) has emerged in clinical and research use. We compared these two methods for determining MT. Methods Left motor cortex MTs were found in 20 healthy subjects. Employing the commonly-used relative frequency procedure and beginning from a clearly suprathreshold intensity, two raters used motor evoked potentials and finger movements respectively to determine EMG-MT and OM-MT. Results OM-MT was 11.3% higher than EMG-MT (p<0.001), ranging from 0-27.8%. In eight subjects, OM-MT was more than 10% higher than EMG-MT, with two greater than 25%. Conclusions These findings suggest using OM yields significantly higher MTs than EMG, and may lead to unsafe TMS in some individuals. In more than half of the subjects in the present study, use of their OM-MT for typical rTMS treatment of depression would have resulted in stimulation beyond safety limits. Significance For applications that involve stimulation near established safety limits and in the presence of factors that could elevate risk such as concomitant medications, EMG-MT is advisable, given that safety guidelines for TMS parameters were based on EMG-MT. PMID:23993680

Lisanby, Sarah H.; Luber, Bruce

2014-01-01

157

Cerebellar dysfunction in progressive supranuclear palsy: a transcranial magnetic stimulation study.  

PubMed

Progressive supranuclear palsy (PSP) rarely shows cerebellar signs and symptoms even though the cerebellar dentate nuclei are involved pathologically. This study evaluates cerebellar function using transcranial magnetic stimulation (TMS) to determine whether subclinical cerebellar involvement is present in PSP patients. We studied 11 patients with PSP, 11 patients with Parkinson's disease (PD), and 10 age-matched controls. Patients were examined with their usual medications and in their relative on state. Motor evoked potentials (MEPs) were recorded from the hand muscle. Cerebellar function was evaluated using suppressive effects of TMS over the cerebellum on MEPs elicited by TMS over the contralateral motor cortex, which we call cerebellar inhibition (CBI). Interstimulus intervals (ISIs) of 4 to 8 ms were used, and the time course of CBI was analyzed. The CBI was reduced in PSP patients. By contrast, the CBI was normal in PD patients in their on state. Although the CBI in their off state should be examined in future studies, the results described herein suggest that Purkinje cells or the dentato-thalamo-cortical pathway assessed by CBI is involved in PSP. Our results are compatible with the pathological findings showing severe dentate nucleus degeneration in PSP patients. PMID:20818672

Shirota, Yuichiro; Hamada, Masashi; Hanajima, Ritsuko; Terao, Yasuo; Matsumoto, Hideyuki; Ohminami, Shinya; Tsuji, Shoji; Ugawa, Yoshikazu

2010-10-30

158

First preoperative functional mapping via navigated transcranial magnetic stimulation in a 3-year-old boy.  

PubMed

Preoperative functional mapping in children younger than 5 years old remains a challenge. Awake functional MRI (fMRI) is usually not an option for these patients. Except for a description of passive fMRI in sedated patients and magnetoencephalography, no other noninvasive mapping method has been reported as a preoperative diagnostic tool in children. Therefore, invasive intraoperative direct cortical stimulation remains the method of choice. To the authors' knowledge, this is the first case of a young child undergoing preoperative functional motor cortex mapping with the aid of navigated transcranial magnetic stimulation (nTMS). In this 3-year-old boy with a rolandic ganglioglioma, awake preoperative mapping was performed using nTMS. A precise location of Broca area 4 could be established. The surgical approach was planned according to the preoperative findings. Intraoperative direct cortical stimulation verified the location of the nTMS hotspots, and complete resection of the precentral tumor was achieved. Navigated TMS is a precise tool for preoperative motor cortex mapping and is feasible even in very young pediatric patients. In children for whom performing the fMRI motor paradigm is challenging, nTMS is the only available option for functional mapping. PMID:22656259

Coburger, Jan; Karhu, Jari; Bittl, Markus; Hopf, Nikolai J

2012-06-01

159

Transcranial magnetic stimulation (TMS) of the supramarginal gyrus: a window to perception of upright.  

PubMed

Although the pull of gravity, primarily detected by the labyrinth, is the fundamental input for our sense of upright, vision and proprioception must also be integrated with vestibular information into a coherent perception of spatial orientation. Here, we used transcranial magnetic stimulation (TMS) to probe the role of the cortex at the temporal parietal junction (TPJ) of the right cerebral hemisphere in the perception of upright. We measured the perceived vertical orientation of a visual line; that is, the subjective visual vertical (SVV), after a short period of continuous theta burst stimulation (cTBS) with the head upright. cTBS over the posterior aspect of the supramarginal gyrus (SMGp) in 8 right-handed subjects consistently tilted the perception of upright when tested with the head tilted 20° to either shoulder (right: 3.6°, left: 2.7°). The tilt of SVV was always in the direction opposite to the head tilt. On the other hand, there was no significant tilt after sham stimulation or after cTBS of nearby areas. These findings suggest that a small area of cerebral cortex-SMGp-has a role in processing information from different sensory modalities into an accurate perception of upright. PMID:24084127

Kheradmand, Amir; Lasker, Adrian; Zee, David S

2015-03-01

160

Effect of cerebellar transcranial magnetic stimulation on soleus Ia presynaptic and reciprocal inhibition.  

PubMed

Previously, we reported that cerebellar transcranial magnetic stimulation (C-TMS) facilitates spinal motoneuronal excitability in resting humans. In this study, we aimed to characterize the descending pathway that is responsible for the C-TMS-associated cerebellar spinal facilitation. We evaluated the effect of C-TMS on ipsilateral soleus Ia presynaptic inhibition (PSI) and reciprocal inhibition (RI) because the vestibulospinal and reticulospinal tracts project from the cerebellum to mediate spinal motoneurons via interneurons associated with PSI. PSI and RI were measured with a soleus H-reflex test following operant conditioning using electrical stimulation of the common peroneal nerve. C-TMS was delivered before test tibial nerve stimulation with conditioning-test interstimulus intervals of 110?ms. C-TMS did not generate motor-evoked potentials, and it did not increase electromyography activity in the ipsilateral soleus muscle, indicating that C-TMS does not directly activate the corticospinal tract and motoneurons. However, C-TMS facilitated the ipsilateral soleus H-reflex and reduced the amount of soleus Ia PSI, but not RI. These findings indicate that C-TMS may facilitate the excitability of the spinal motoneuron pool via the vestibulospinal or reticulospinal tracts associated with PSI. Cerebellar spinal facilitation may be useful for assessing the functional connectivity of the cerebellum and vestibular nuclei or reticular formation. PMID:25569794

Matsugi, Akiyoshi; Mori, Nobuhiko; Uehara, Shintaro; Kamata, Noriyuki; Oku, Kosuke; Okada, Yohei; Kikuchi, Yutaka; Mukai, Kouichi; Nagano, Kiyoshi

2015-02-11

161

Using transcranial magnetic stimulation to quantify electrophysiological changes following concussive brain injury: A systematic review.  

PubMed

Mild traumatic brain injury (mTBI) and sports concussion are a growing public health concern, with increasing demands for more rigorous methods to quantify changes in the brain post-injury. Electrophysiology, and in particular, transcranial magnetic stimulation (TMS), have been demonstrated to provide prognostic value in a range of neurological conditions; however, no review has quantified the efficacy of TMS in mTBI/concussion. In the present study, we present a systematic review and critical evaluation of the scientific literature from 1990 to 2014 that has used TMS to investigate corticomotor excitability responses at short-term (< 12 months), medium-term (1-5 years), and long-term (> 5 years) post-mTBI/concussion. Thirteen studies met the selection criteria, with six studies presenting short-term changes, five studies presenting medium-term changes, and two studies presenting long-term changes. Irrespective of time post-concussion, change in intracortical inhibition was the most reported observation. Other findings included increased stimulation threshold, and slowed neurological conduction time. Although currently limited, the data suggest that TMS has prognostic value in detecting neurophysiological changes post-mTBI/concussion. PMID:25603731

Major, Brendan P; Rogers, Mark A; Pearce, Alan J

2015-04-01

162

Voltage-sensitive dye imaging of transcranial magnetic stimulation-induced intracortical dynamics  

PubMed Central

Transcranial magnetic stimulation (TMS) is widely used in clinical interventions and basic neuroscience. Additionally, it has become a powerful tool to drive plastic changes in neuronal networks. However, highly resolved recordings of the immediate TMS effects have remained scarce, because existing recording techniques are limited in spatial or temporal resolution or are interfered with by the strong TMS-induced electric field. To circumvent these constraints, we performed optical imaging with voltage-sensitive dye (VSD) in an animal experimental setting using anaesthetized cats. The dye signals reflect gradual changes in the cells' membrane potential across several square millimeters of cortical tissue, thus enabling direct visualization of TMS-induced neuronal population dynamics. After application of a single TMS pulse across visual cortex, brief focal activation was immediately followed by synchronous suppression of a large pool of neurons. With consecutive magnetic pulses (10 Hz), widespread activity within this “basin of suppression” increased stepwise to suprathreshold levels and spontaneous activity was enhanced. Visual stimulation after repetitive TMS revealed long-term potentiation of evoked activity. Furthermore, loss of the “deceleration–acceleration” notch during the rising phase of the response, as a signature of fast intracortical inhibition detectable with VSD imaging, indicated weakened inhibition as an important driving force of increasing cortical excitability. In summary, our data show that high-frequency TMS changes the balance between excitation and inhibition in favor of an excitatory cortical state. VSD imaging may thus be a promising technique to trace TMS-induced changes in excitability and resulting plastic processes across cortical maps with high spatial and temporal resolutions. PMID:25187557

Kozyrev, Vladislav; Eysel, Ulf T.; Jancke, Dirk

2014-01-01

163

Repetitive transcranial magnetic stimulation for clinical applications in neurological and psychiatric disorders: an overview.  

PubMed

Neurological and psychiatric disorders are characterized by several disabling symptoms for which effective, mechanism-based treatments remain elusive. Consequently, more advanced non-invasive therapeutic methods are required. A method that may modulate brain activity and be viable for use in clinical practice is repetitive transcranial magnetic stimulation (rTMS). It is a non-invasive procedure whereby a pulsed magnetic field stimulates electrical activity in the brain. Here, we focus on the basic foundation of rTMS, the main stimulation parametters, the factors that influence individual responses to rTMS and the experimental advances of rTMS that may become a viable clinical application to treat neurological and psychiatric disorders. The findings showed that rTMS can improve some symptoms associated with these conditions and might be useful for promoting cortical plasticity in patients with neurological and psychiatric disorders. However, these changes are transient and it is premature to propose these applications as realistic therapeutic options, even though the rTMS technique has been evidenced as a potential modulator of sensorimotor integration and neuroplasticity. Functional imaging of the region of interest could highlight the capacity of rTMS to bring about plastic changes of the cortical circuitry and hint at future novel clinical interventions. Thus, we recommend that further studies clearly determine the role of rTMS in the treatment of these conditions. Finally, we must remember that however exciting the neurobiological mechanisms might be, the clinical usefulness of rTMS will be determined by its ability to provide patients with neurological and psychiatric disorders with safe, long-lasting and substantial improvements in quality of life. PMID:25610279

Machado, Sergio; Arias-Carrión, Oscar; Paes, Flávia; Vieira, Renata Teles; Caixeta, Leonardo; Novaes, Felipe; Marinho, Tamires; Almada, Leonardo Ferreira; Silva, Adriana Cardoso; Nardi, Antonio Egidio

2013-10-01

164

Repetitive Transcranial Magnetic Stimulation for Clinical Applications in Neurological and Psychiatric Disorders: An Overview  

PubMed Central

Neurological and psychiatric disorders are characterized by several disabling symptoms for which effective, mechanism-based treatments remain elusive. Consequently, more advanced non-invasive therapeutic methods are required. A method that may modulate brain activity and be viable for use in clinical practice is repetitive transcranial magnetic stimulation (rTMS). It is a non-invasive procedure whereby a pulsed magnetic field stimulates electrical activity in the brain. Here, we focus on the basic foundation of rTMS, the main stimulation parametters, the factors that influence individual responses to rTMS and the experimental advances of rTMS that may become a viable clinical application to treat neurological and psychiatric disorders. The findings showed that rTMS can improve some symptoms associated with these conditions and might be useful for promoting cortical plasticity in patients with neurological and psychiatric disorders. However, these changes are transient and it is premature to propose these applications as realistic therapeutic options, even though the rTMS technique has been evidenced as a potential modulator of sensorimotor integration and neuroplasticity. Functional imaging of the region of interest could highlight the capacity of rTMS to bring about plastic changes of the cortical circuitry and hint at future novel clinical interventions. Thus, we recommend that further studies clearly determine the role of rTMS in the treatment of these conditions. Finally, we must remember that however exciting the neurobiological mechanisms might be, the clinical usefulness of rTMS will be determined by its ability to provide patients with neurological and psychiatric disorders with safe, long-lasting and substantial improvements in quality of life. PMID:25610279

Machado, Sergio; Arias-Carrión, Oscar; Paes, Flávia; Vieira, Renata Teles; Caixeta, Leonardo; Novaes, Felipe; Marinho, Tamires; Almada, Leonardo Ferreira; Silva, Adriana Cardoso; Nardi, Antonio Egidio

2013-01-01

165

Responses to rapid-rate transcranial magnetic stimulation of the human motor cortex.  

PubMed

We applied trains of focal, rapid-rate transcranial magnetic stimulation (rTMS) to the motor cortex of 14 healthy volunteers with recording of the EMG from the contralateral abductor pollicis brevis, extensor carpi radialis, biceps brachii and deltoid muscles. Modulation of the amplitude of motor evoked potentials (MEPs) produced in the target muscle during rTMS showed a pattern of inhibitory and excitatory effects which depended on the rTMS frequency and intensity. With the magnetic coil situated over the optimal scalp position for activating the abductor pollicis brevis, rTMS led to spread of excitation, as evident from the induction of progressively larger MEPs in the other muscles. The number of pulses inducing this spread of excitation decreased with increasing rTMS frequency and intensity. Latency of the MEPs produced in the other muscles during the spread of excitation was significantly longer than that produced by single-pulse TMS applied to the optimal scalp positions for their activation. The difference in MEP latency could be explained by a delay in intracortical conduction along myelinated cortico-cortical pathways. Following rTMS, a 3-4 min period of increased excitability was demonstrated by an increase in the amplitude of MEPs produced in the target muscles by single-pulse TMS. Nevertheless, repeated rTMS trains applied 1 min apart led to similar modulation of the responses and to spread of excitation after approximately the same number of pulses. This suggests that the spread might be due to the breakdown of inhibitory connections or the recruitment of excitatory pathways, whereas the post-stimulation facilitation may be due to a transient increase in the efficacy of excitatory synapses. PMID:7922470

Pascual-Leone, A; Valls-Solé, J; Wassermann, E M; Hallett, M

1994-08-01

166

Tracking post-error adaptation in the motor system by transcranial magnetic stimulation.  

PubMed

The commission of an error triggers cognitive control processes dedicated to error correction and prevention. Post-error adjustments leading to response slowing following an error ("post-error slowing"; PES) might be driven by changes in excitability of the motor regions and the corticospinal tract (CST). The time-course of such excitability modulations of the CST leading to PES is largely unknown. To track these presumed excitability changes after an error, single pulse transcranial magnetic stimulation (TMS) was applied to the motor cortex ipsilateral to the responding hand, while participants were performing an Eriksen flanker task. A robotic arm with a movement compensation system was used to maintain the TMS coil in the correct position during the experiment. Magnetic pulses were delivered over the primary motor cortex ipsilateral to the active hand at different intervals (150, 300, 450 ms) after correct and erroneous responses, and the motor-evoked potentials (MEP) of the first dorsal interosseous muscle (FDI) contralateral to the stimulated hemisphere were recorded. MEP amplitude was increased 450 ms after the error. Two additional experiments showed that this increase was neither associated to the correction of the erroneous responses nor to the characteristics of the motor command. To the extent to which the excitability of the motor cortex ipsi- and contralateral to the response hand are inversely related, these results suggest a decrease in the excitability of the active motor cortex after an erroneous response. This modulation of the activity of the CST serves to prevent further premature and erroneous responses. At a more general level, the study shows the power of the TMS technique for the exploration of the temporal evolution of post-error adjustments within the motor system. PMID:23876325

Amengual, J L; Marco-Pallarés, J; Richter, L; Oung, S; Schweikard, A; Mohammadi, B; Rodríguez-Fornells, A; Münte, T F

2013-10-10

167

Investigating Representations of Facial Identity in Human Ventral Visual Cortex with Transcranial Magnetic Stimulation  

PubMed Central

The occipital face area (OFA) is face-selective. This enhanced activation to faces could reflect either generic face and shape-related processing or high-level conceptual processing of identity. Here we examined these two possibilities using a state-dependent transcranial magnetic stimulation (TMS) paradigm. The lateral occipital (LO) cortex which is activated non-selectively by various types of objects served as a control site. We localized OFA and LO on a per-participant basis using functional MRI. We then examined whether TMS applied to either of these regions affected the ability of participants to decide whether two successively presented and physically different face images were of the same famous person or different famous people. TMS was applied during the delay between first and second face presentations to investigate whether neuronal populations in these regions played a causal role in mediating the behavioral effects of identity repetition. Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different. Surprisingly, TMS applied over LO (but not OFA) modulated overall RTs, compared to the No-TMS condition. But critically, we found no effects of TMS to either area that were modulated by identity repetition. Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing. Instead, these brain regions may be involved in the processing of more generic features of their preferred stimulus categories. PMID:20631842

Gilaie-Dotan, Sharon; Silvanto, Juha; Schwarzkopf, Dietrich S.; Rees, Geraint

2010-01-01

168

Correlation between motor and phosphene thresholds: a transcranial magnetic stimulation study.  

PubMed

Transcranial magnetic stimulation (TMS) has become a common tool for the brain mapping of a wide variety of cognitive functions. Because TMS over cortical regions of interest other than motor cortex often does not produce easily observable effects, the ability to calibrate TMS intensity for stimulation over nonmotor regions can be problematic. Previous studies reported no correlation between motor thresholds (MT) over the motor cortex and phosphene thresholds (PT) over the visual cortex. However, different thresholding methods, lighting, and eye-closure conditions were used to determine MT and PT. We investigated the correlation between resting MT (rMT), active MT (aMT), and PT in 27 dark-adapted healthy volunteers. All thresholds were measured with eyes-open in the dark and determined by gradually reducing stimulation intensity downward. All subjects had aMT and rMT; 21 subjects had measurable PT. rMT was 70.4% +/- 9.8% (mean +/- SD of maximum stimulator output); aMT was 61.1% +/- 7.9%; PT was 82.2% +/- 10.1%. A significant positive correlation was found between aMT and PT (r = 0.53; P = 0.014) with a trend toward correlation between rMT and PT (r = 0.43; P = 0.052). Our results suggest that sensitivity to TMS over visual and motor cortices may be correlated under similar thresholding procedures. They also provide a rationale for the use of easily obtained aMT to calibrate TMS intensities in brain mapping studies that employ TMS in cortical regions besides motor cortex. PMID:17598167

Deblieck, Choi; Thompson, Benjamin; Iacoboni, Marco; Wu, Allan D

2008-06-01

169

Changes in Voluntary Activation Assessed by Transcranial Magnetic Stimulation during Prolonged Cycling Exercise  

PubMed Central

Maximal central motor drive is known to decrease during prolonged exercise although it remains to be determined whether a supraspinal deficit exists, and if so, when it appears. The purpose of this study was to evaluate corticospinal excitability and muscle voluntary activation before, during and after a 4-h cycling exercise. Ten healthy subjects performed three 80-min bouts on an ergocycle at 45% of their maximal aerobic power. Before exercise and immediately after each bout, neuromuscular function was evaluated in the quadriceps femoris muscles under isometric conditions. Transcranial magnetic stimulation was used to assess voluntary activation at the cortical level (VATMS), corticospinal excitability via motor-evoked potential (MEP) and intracortical inhibition by cortical silent period (CSP). Electrical stimulation of the femoral nerve was used to measure voluntary activation at the peripheral level (VAFNES) and muscle contractile properties. Maximal voluntary force was significantly reduced after the first bout (13±9%, P<0.01) and was further decreased (25±11%, P<0.001) at the end of exercise. CSP remained unchanged throughout the protocol. Rectus femoris and vastus lateralis but not vastus medialis MEP normalized to maximal M-wave amplitude significantly increased during cycling. Finally, significant decreases in both VATMS and VAFNES (?8%, P<0.05 and ?14%, P<0.001 post-exercise, respectively) were observed. In conclusion, reductions in VAFNES after a prolonged cycling exercise are partly explained by a deficit at the cortical level accompanied by increased corticospinal excitability and unchanged intracortical inhibition. When comparing the present results with the literature, this study highlights that changes at the cortical and/or motoneuronal levels depend not only on the type of exercise (single-joint vs. whole-body) but also on exercise intensity and/or duration. PMID:24586559

Perrey, Stephane; Temesi, John; Wuyam, Bernard; Levy, Patrick; Verges, Samuel; Millet, Guillaume Y.

2014-01-01

170

Cortical excitability changes after high-frequency repetitive transcranial magnetic stimulation for central poststroke pain.  

PubMed

Central poststroke pain (CPSP) is one of the most refractory chronic pain syndromes. Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex has been demonstrated to provide moderate pain relief for CPSP. However, the mechanism underlying the pain relief remains unclear. The objective of this study was to assess changes in cortical excitability in patients with intractable CPSP before and after rTMS of the primary motor cortex. Subjects were 21 patients with CPSP of the hand who underwent rTMS. The resting motor threshold, the amplitude of the motor evoked potential, duration of the cortical silent period, short interval intracortical inhibition, and intracortical facilitation were measured as parameters of cortical excitability before and after navigation-guided 5 Hz rTMS of the primary motor cortex corresponding to the painful hand. Pain reduction from rTMS was assessed with a visual analog scale. The same parameters were measured in both hemispheres of 8 healthy controls. Eight of 21 patients experienced ? 30% pain reduction after rTMS (responders). The resting motor threshold in the patients was higher than those in the controls at baseline (P=.035). Intracortical facilitation in the responders was lower than in the controls and the nonresponders at baseline (P=.035 and P=.019), and significantly increased after rTMS (P=.039). There were no significant differences or changes in the other parameters. Our findings suggest that restoration of abnormal cortical excitability might be one of the mechanisms underlying pain relief as a result of rTMS in CPSP. PMID:23707310

Hosomi, Koichi; Kishima, Haruhiko; Oshino, Satoru; Hirata, Masayuki; Tani, Naoki; Maruo, Tomoyuki; Yorifuji, Shiro; Yoshimine, Toshiki; Saitoh, Youichi

2013-08-01

171

Modulation of corticospinal excitability by transcranial magnetic stimulation in children and adolescents with autism spectrum disorder  

PubMed Central

The developmental pathophysiology of autism spectrum disorders (ASD) is currently not fully understood. However, multiple lines of evidence suggest that the behavioral phenotype may result from dysfunctional inhibitory control over excitatory synaptic plasticity. Consistent with this claim, previous studies indicate that adults with Asperger’s Syndrome show an abnormally extended modulation of corticospinal excitability following a train of repetitive transcranial magnetic stimulation (rTMS). As ASD is a developmental disorder, the current study aimed to explore the effect of development on the duration of modulation of corticospinal excitability in children and adolescents with ASD. Additionally, as the application of rTMS to the understanding and treatment of pediatric neurological and psychiatric disorders is an emerging field, this study further sought to provide evidence for the safety and tolerability of rTMS in children and adolescents with ASD. Corticospinal excitability was measured by applying single pulses of TMS to the primary motor cortex both before and following a 40 s train of continuous theta burst stimulation. 19 high-functioning males ages 9–18 with ASD participated in this study. Results from this study reveal a positive linear relationship between age and duration of modulation of rTMS after-effects. Specifically we found that the older participants had a longer lasting response. Furthermore, though the specific protocol employed typically suppresses corticospinal excitability in adults, more than one third of our sample had a paradoxical facilitatory response to the stimulation. Results support the safety and tolerability of rTMS in pediatric clinical populations. Data also support published theories implicating aberrant plasticity and GABAergic dysfunction in this population. PMID:25165441

Oberman, Lindsay M.; Pascual-Leone, Alvaro; Rotenberg, Alexander

2014-01-01

172

Effects of repetitive transcranial magnetic stimulation on the somatosensory cortex during prism adaptation.  

PubMed

Although the behavioral characteristics and the neural correlates of prism adaptation processes have been studied extensively, the underlying mechanism is yet to be investigated. Recently, somatosensory suppression was heralded as a mechanism for the sensory re-alignment process accompanying the adaptation. Somatosensory suppression should facilitate the re-alignment process in the proprioceptive system. The shift in the proprioceptive system takes place mostly during a concurrent visual feedback (CVF) condition; during a terminal visual feedback (TVF) condition, the visual system experiences significant adaptation (visual shift), so somatosensory suppression should have minimal functional consequences under TVF. To test this hypothesis, a repetitive transcranial magnetic stimulation (rTMS) was applied to the primary somatosensory cortex as an artificial somatosensory suppression right after the reaching initiation in CVF and TVF conditions, and changes in adaptation were observed. Because somatosensory suppression is already in effect during CVF, rTMS would cause no significant changes. During TVF with rTMS, however, significantly different patterns of adaptation could be expected when compared to a sham rTMS condition. Young adults (N = 12) participated in 4 sessions (CVF/ TVF, real/sham rTMS); visual proprioceptive, and total shifts were measured. Movement time and curvature of the reaching movement were measured during the adaptation phase. Results showed that while the total shift was unchanged, the proprioceptive shift increased and the visual shift decreased in the TVF condition when rTMS was delivered. However, the total, proprioceptive, and visual shifts were not influenced by rTMS in the CVF condition. Suppression of proprioception induced by the rTMS could be one of the requisites for successful proprioceptive shift during prism adaptation. PMID:24897882

Yoon, Hee-Chul; Lee, Kyung-Hyun; Huh, Dong-Chan; Lee, Ji-Hang; Lee, Dong-Hyun

2014-04-01

173

Mechanisms of human motor cortex facilitation induced by subthreshold 5-Hz repetitive transcranial magnetic stimulation.  

PubMed

Our knowledge about the mechanisms of human motor cortex facilitation induced by repetitive transcranial magnetic stimulation (rTMS) is still incomplete. Here we used pharmacological conditioning with carbamazepine, dextrometorphan, lorazepam, and placebo to elucidate the type of plasticity underlying this facilitation, and to probe if mechanisms reminiscent of long-term potentiation are involved. Over the primary motor cortex of 10 healthy subjects, we applied biphasic rTMS pulses of effective posterior current direction in the brain. We used six blocks of 200 pulses at 5-Hz frequency and 90% active motor threshold intensity and controlled for corticospinal excitability changes using motor-evoked potential (MEP) amplitudes and latencies elicited by suprathreshold pulses before, in between, and after rTMS. Target muscle was the dominant abductor digiti minimi muscle; we coregistered the dominant extensor carpi radialis muscle. We found a lasting facilitation induced by this type of rTMS. The GABAergic medication lorazepam and to a lesser extent the ion channel blocker carbamazepine reduced the MEP facilitation after biphasic effective posteriorly oriented rTMS, whereas the N-methyl-d-aspartate receptor-antagonist dextrometorphan had no effect. Our main conclusion is that the mechanism of the facilitation induced by biphasic effective posterior rTMS is more likely posttetanic potentiation than long-term potentiation. Additional findings were prolonged MEP latency under carbamazepine, consistent with sodium channel blockade, and larger MEP amplitudes from extensor carpi radialis under lorazepam, suggesting GABAergic involvement in the center-surround balance of excitability. PMID:23536708

Sommer, Martin; Rummel, Milena; Norden, Christoph; Rothkegel, Holger; Lang, Nicolas; Paulus, Walter

2013-06-01

174

The Role of Pulse Shape in Motor Cortex Transcranial Magnetic Stimulation Using Full-Sine Stimuli  

PubMed Central

A full-sine (biphasic) pulse waveform is most commonly used for repetitive transcranial magnetic stimulation (TMS), but little is known about how variations in duration or amplitude of distinct pulse segments influence the effectiveness of a single TMS pulse to elicit a corticomotor response. Using a novel TMS device, we systematically varied the configuration of full-sine pulses to assess the impact of configuration changes on resting motor threshold (RMT) as measure of stimulation effectiveness with single-pulse TMS of the non-dominant motor hand area (M1). In young healthy volunteers, we (i) compared monophasic, half-sine, and full-sine pulses, (ii) applied two-segment pulses consisting of two identical half-sines, and (iii) manipulated amplitude, duration, and current direction of the first or second full-sine pulse half-segments. RMT was significantly higher using half-sine or monophasic pulses compared with full-sine. Pulses combining two half-sines of identical polarity and duration were also characterized by higher RMT than full-sine stimuli resulting. For full-sine stimuli, decreasing the amplitude of the half-segment inducing posterior-anterior oriented current in M1 resulted in considerably higher RMT, whereas varying the amplitude of the half-segment inducing anterior-posterior current had a smaller effect. These findings provide direct experimental evidence that the pulse segment inducing a posterior-anterior directed current in M1 contributes most to corticospinal pathway excitation. Preferential excitation of neuronal target cells in the posterior-anterior segment or targeting of different neuronal structures by the two half-segments can explain this result. Thus, our findings help understanding the mechanisms of neural stimulation by full-sine TMS. PMID:25514673

Delvendahl, Igor; Gattinger, Norbert; Berger, Thomas; Gleich, Bernhard; Siebner, Hartwig R.; Mall, Volker

2014-01-01

175

Therapeutic effects of repetitive transcranial magnetic stimulation in an animal model of Parkinson's disease.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is used to treat neurological diseases such as stroke and Parkinson's disease (PD). Although rTMS has been used clinically, its underlying therapeutic mechanism remains unclear. The objective of the present study was to clarify the neuroprotective effect and therapeutic mechanism of rTMS in an animal model of PD. Adult Sprague-Dawley rats were unilaterally injected with 6-hydroxydopamine (6-OHDA) into the right striatum. Rats with PD were then treated with rTMS (circular coil, 10 Hz, 20 min/day) daily for 4 weeks. Behavioral assessments such as amphetamine-induced rotational test and treadmill locomotion test were performed, and the dopaminergic (DA) neurons of substantia nigra pas compacta (SNc) and striatum were histologically examined. Expression of neurotrophic/growth factors was also investigated by multiplex ELISA, western blotting analysis and immunohistochemistry 4 weeks after rTMS application. Among the results, the number of amphetamine-induced rotations was significantly lower in the rTMS group than in the control group at 4 weeks post-treatment. Treadmill locomotion was also significantly improved in the rTMS-treated rats. Tyrosine hydroxylase-positive DA neurons and DA fibers in rTMS group rats were greater than those in untreated group in both ipsilateral SNc and striatum, respectively. The expression levels of brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, platelet-derived growth factor, and vascular endothelial growth factor were elevated in both the 6-OHDA-injected hemisphere and the SNc of the rTMS-treated rats. In conclusion, rTMS treatment improved motor functions and survival of DA neurons, suggesting that the neuroprotective effect of rTMS treatment might be induced by upregulation of neurotrophic/growth factors in the PD animal model. PMID:23998987

Lee, Ji Yong; Kim, Sung Hoon; Ko, Ah-Ra; Lee, Jin Suk; Yu, Ji Hea; Seo, Jung Hwa; Cho, Byung Pil; Cho, Sung-Rae

2013-11-01

176

A neurophysiological insight into the potential link between transcranial magnetic stimulation, thalamocortical dysrhythmia and neuropsychiatric disorders.  

PubMed

Altered neural oscillations and their abnormal synchronization are crucial factors in the pathophysiology of several neuropsychiatric disorders. There is increasing evidence that the perturbation with an abnormal increase of spontaneous thalamocortical neural oscillations lead to a phenomenon termed Thalamocortical dysrhythmia (TCD) which underlies the symptomatology of a variety of neurological and psychiatric disorders including Parkinson's disease, schizophrenia, epilepsy, neuropathic pain, tinnitus, major depression and obsessive-compulsive disorder. In addition, repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neurophysiological tool that has been shown to both induce a modulation of neural oscillations and alleviate a wide range of human neuropsychiatric pathologies. However, little is known about the precise electrophysiological mechanisms behind the therapeutic effect of rTMS and its potential to improve abnormal oscillations across diverse neuropsychiatric disorders. Here we show, using combined rTMS and surface electroencephalography (EEG), a short lasting frequency-dependent rTMS after-effect on thalamocortical rhythmic interplay of low-frequency oscillations in healthy humans at rest. In particular, high-frequency rTMS (10 Hz) induces a transient synchronised activity for delta (?) and theta (?) rhythms thus mimicking the pathological TCD-like oscillations. In contrast, rTMS 1 and 5 Hz have the opposite outcome of de-synchronising low-frequency brain rhythms. These results lead to a new neurophysiological insight of basic mechanisms underlying neurological and psychiatric disorders and a probable electrophysiological mechanism underlying the therapeutic effects of rTMS. Thus, we propose the use of rTMS and EEG as a platform to test possible treatments of TCD phenotypes by restoring proper neural oscillations across various neuropsychiatric disorders. PMID:23063603

Fuggetta, Giorgio; Noh, Nor Azila

2013-07-01

177

Uncertainty quantification in transcranial magnetic stimulation via high-dimensional model representation.  

PubMed

A computational framework for uncertainty quantification in transcranial magnetic stimulation (TMS) is presented. The framework leverages high-dimensional model representations (HDMRs), which approximate observables (i.e., quantities of interest such as electric (E) fields induced inside targeted cortical regions) via series of iteratively constructed component functions involving only the most significant random variables (i.e., parameters that characterize the uncertainty in a TMS setup such as the position and orientation of TMS coils, as well as the size, shape, and conductivity of the head tissue). The component functions of HDMR expansions are approximated via a multielement probabilistic collocation (ME-PC) method. While approximating each component function, a quasi-static finite-difference simulator is used to compute observables at integration/collocation points dictated by the ME-PC method. The proposed framework requires far fewer simulations than traditional Monte Carlo methods for providing highly accurate statistical information (e.g., the mean and standard deviation) about the observables. The efficiency and accuracy of the proposed framework are demonstrated via its application to the statistical characterization of E-fields generated by TMS inside cortical regions of an MRI-derived realistic head model. Numerical results show that while uncertainties in tissue conductivities have negligible effects on TMS operation, variations in coil position/orientation and brain size significantly affect the induced E-fields. Our numerical results have several implications for the use of TMS during depression therapy: 1) uncertainty in the coil position and orientation may reduce the response rates of patients; 2) practitioners should favor targets on the crest of a gyrus to obtain maximal stimulation; and 3) an increasing scalp-to-cortex distance reduces the magnitude of E-fields on the surface and inside the cortex. PMID:25203980

Gomez, Luis J; Yücel, Abdulkadir C; Hernandez-Garcia, Luis; Taylor, Stephan F; Michielssen, Eric

2015-01-01

178

Perfusion MRI Indexes Variability in the Functional Brain Effects of Theta-Burst Transcranial Magnetic Stimulation  

PubMed Central

Transcranial Magnetic Stimulation (TMS) is an important tool for testing causal relationships in cognitive neuroscience research. However, the efficacy of TMS can be variable across individuals and difficult to measure. This variability is especially a challenge when TMS is applied to regions without well-characterized behavioral effects, such as in studies using TMS on multi-modal areas in intrinsic networks. Here, we examined whether perfusion fMRI recordings of Cerebral Blood Flow (CBF), a quantitative measure sensitive to slow functional changes, reliably index variability in the effects of stimulation. Twenty-seven participants each completed four combined TMS-fMRI sessions during which both resting state Blood Oxygen Level Dependent (BOLD) and perfusion Arterial Spin Labeling (ASL) scans were recorded. In each session after the first baseline day, continuous theta-burst TMS (TBS) was applied to one of three locations: left dorsolateral prefrontal cortex (L dlPFC), left anterior insula/frontal operculum (L aI/fO), or left primary somatosensory cortex (L S1). The two frontal targets are components of intrinsic networks and L S1 was used as an experimental control. CBF changes were measured both before and after TMS on each day from a series of interleaved resting state and perfusion scans. Although TBS led to weak selective increases under the coil in CBF measurements across the group, individual subjects showed wide variability in their responses. TBS-induced changes in rCBF were related to TBS-induced changes in functional connectivity of the relevant intrinsic networks measured during separate resting-state BOLD scans. This relationship was selective: CBF and functional connectivity of these networks were not related before TBS or after TBS to the experimental control region (S1). Furthermore, subject groups with different directions of CBF change after TBS showed distinct modulations in the functional interactions of targeted networks. These results suggest that CBF is a marker of individual differences in the effects of TBS. PMID:24992641

Gratton, Caterina; Lee, Taraz G.; Nomura, Emi M.; D’Esposito, Mark

2014-01-01

179

Volitional muscle activity paired with transcranial magnetic stimulation increases corticospinal excitability  

PubMed Central

Studies of activity-dependent stimulation in non-human primates suggest that pairing each instance of volitional muscle activity with immediate intracortical stimulation causes long-term-potentiation-like effects. This technique holds promise for clinical rehabilitation, yet few investigators have tested activity-dependent stimulation in human subjects. In addition, no one has studied activity-dependent stimulation on the cortical representation for two separate target muscles in human subjects. We hypothesized that 40 min of transcranial magnetic stimulation (TMS) triggered from ballistic muscle activity at a mean repetition rate of 1 Hz would cause greater increases in corticospinal excitability than TMS-cued muscle activity, and that these changes would be specific to the muscle of study. Ten healthy human subjects participated in 4 separate sessions in this crossover study: (1) visually cued volitional activation of the abductor pollicis brevis (APB) muscle triggering TMS (APB-Triggered TMS), (2) volitional activation of APB in response to TMS delivered from a recording of the prior APB-Triggered TMS session (TMS-Cued APB), (3) visually cued volitional activation of the extensor digitorum (ED) triggering TMS (ED-Triggered TMS), and (4) volitional activation of ED in response to TMS delivered from a recording of the prior ED-Triggered TMS session (TMS-Cued ED). Contrary to our hypothesis, we discovered evidence of increased corticospinal excitability for all conditions as measured by change in area of the motor evoked potential. We conclude that single TMS pulses paired either before or after muscle activity may increase corticospinal excitability and that further studies are needed to clarify the optimal time window for inducing neural plasticity with activity-dependent stimulation. These findings will inform the design of future activity-dependent stimulation protocols for clinical rehabilitation. PMID:25628525

Edwardson, Matthew A.; Avery, David H.; Fetz, Eberhard E.

2015-01-01

180

Enhancement of single motor unit inhibitory responses to transcranial magnetic stimulation in amyotrophic lateral sclerosis.  

PubMed

In healthy human subjects, transcranial magnetic stimulation (TMS) applied to the motor cortex induces concurrent inhibitory and excitatory effects on motoneurone activity. In amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting both cortical and spinal motor neurons, paired-pulse studies based on electromyographic (EMG) recording have revealed a decrease in TMS-induced inhibition. This suggested that inhibition loss may promote excito-toxicity in this disease. Against this hypothesis, an abnormally high incidence of inhibitory responses to TMS has been observed in the peristimulus time histograms (PSTHs) in ALS single motor unit studies. The disappearance of cortico-motoneuronal excitatory inputs might, however, have facilitated the detection of single motor unit inhibitory responses in the PSTHs. This question was addressed here using a new approach, where the strength of the excitatory and inhibitory effects of TMS on motoneurone activity was assessed from the duration of inter-spike intervals (ISIs). This analysis was conducted on single motor unit (MU), tested on healthy subjects and patients with ALS or Kennedy's disease (KD), a motor neuron disease which unlike ALS, spares the cortico-spinal pathway. MUs tested on KD patients behaved like those of healthy subjects unlike those tested on ALS patients. The present data reveal that in ALS, the TMS-induced inhibitory effects are truly enhanced during voluntary contractions and not reduced, as observed in paired-pulse TMS studies under resting conditions. The possible contribution of inhibitory loss to the physiopathology of ALS therefore needs to be reconsidered. The present data do not support the idea that inhibition loss may underlie excito-toxicity in ALS. PMID:18496679

Schmied, Annie; Attarian, Shahram

2008-08-01

181

Mirror Neuron Dysfunction and Ego-Boundary Disturbances in Schizophrenia: A Transcranial Magnetic Stimulation Study  

PubMed Central

Background: Ego-boundary disturbance (EBD) is a unique symptom cluster characterized by passivity experiences (involving thoughts, actions, emotions and sensations) attributed by patients to some external agency. The neurobiology of these “first rank” symptoms is poorly understood. Aberrant mirror neuron activation may explain impaired self-monitoring and agency attribution underlying these symptoms. We aim to study mirror neuron activity (MNA) in schizophrenia patients with and without EBD using transcranial magnetic stimulation (TMS). Materials and Methods: 50 right-handed schizophrenia patients (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) were evaluated using the Mini-International Neuropsychiatric Interview and the Positive and Negative Syndrome Scale. They completed a TMS experiment to assess putative premotor MNA. Motor evoked potential (MEP) was recorded in the right first dorsal interosseous muscle (FDI) with (a) 120% of resting motor threshold (RMT), (b) stimulus intensity set to evoke MEP of motor threshold 1 mV amplitude (MT1), (c) two paired pulse paradigms (short- and long interval intra-cortical inhibition). These were done in three states: Actual observation of an action using the FDI, virtual-observation (video) of this action and resting state. The percent change of MEP from resting to action-observation states formed the measure of putative MNA. Results: MNA measured using MT1 and 120% RMT paradigms was significantly lower in the 18 patients with EBD (thought-broadcast/withdrawal/insertion, made-act/impulse/affect and somatic passivity) than the 32 patients without EBD (t = 2.431, P = 0.020; t = 2.051, P = 0.04 respectively for the two paradigms). The two groups did not differ on age, gender, education and total symptom scores. Conclusion: Schizophrenia patients with EBD have lower premotor MNA. This highlights the role of MNA dysfunction in the pathophysiology of this unique and intriguing symptom cluster in schizophrenia. PMID:25722514

Basavaraju, Rakshathi; Mehta, Urvakhsh Meherwan; Thirthalli, Jagadisha; Gangadhar, Bangalore N.

2015-01-01

182

Electric field depth–focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs  

PubMed Central

Background Various transcranial magnetic stimulation (TMS) coil designs are available or have been proposed. However, key coil characteristics such as electric field focality and attenuation in depth have not been adequately compared. Knowledge of the coil focality and depth characteristics can help TMS researchers and clinicians with coil selection and interpretation of TMS studies. Objective To quantify the electric field focality and depth of penetration of various TMS coils. Methods The electric field distributions induced by 50 TMS coils were simulated in a spherical human head model using the finite element method. For each coil design, we quantified the electric field penetration by the half-value depth, d1/2, and focality by the tangential spread, S1/2, defined as the half-value volume (V1/2) divided by the half-value depth, S1/2 = V1/2/d1/2. Results The 50 TMS coils exhibit a wide range of electric field focality and depth, but all followed a depth–focality tradeoff: coils with larger half-value depth cannot be as focal as more superficial coils. The ranges of achievable d1/2 are similar between coils producing circular and figure-8 electric field patterns, ranging 1.0–3.5 cm and 0.9–3.4 cm, respectively. However, figure-8 field coils are more focal, having S1/2 as low as 5 cm2 compared to 34 cm2 for circular field coils. Conclusions For any coil design, the ability to directly stimulate deeper brain structures is obtained at the expense of inducing wider electrical field spread. Novel coil designs should be benchmarked against comparison coils with consistent metrics such as d1/2 and S1/2. PMID:22483681

Deng, Zhi-De; Lisanby, Sarah H.; Peterchev, Angel V.

2012-01-01

183

Conditioning effect of transcranial magnetic stimulation evoking motor?evoked potential on V?wave response  

PubMed Central

Abstract The aim of this study was to examine the collision responsible for the volitional V?wave evoked by supramaximal electrical stimulation of the motor nerve during voluntary contraction. V?wave was conditioned by transcranial magnetic stimulation (TMS) over the motor cortex at several inter?stimuli intervals (ISI) during weak voluntary plantar flexions (n = 10) and at rest for flexor carpi radialis muscle (FCR; n = 6). Conditioning stimulations were induced by TMS with intensity eliciting maximal motor?evoked potential (MEPmax). ISIs used were ranging from ?20 to +20 msec depending on muscles tested. The results showed that, for triceps surae muscles, conditioning TMS increased the V?wave amplitude (~ +250%) and the associated mechanical response (~ +30%) during weak voluntary plantar flexion (10% of the maximal voluntary contraction ?MVC) for ISIs ranging from +6 to +18 msec. Similar effect was observed at rest for the FCR with ISI ranging from +6 to +12 msec. When the level of force was increased from 10 to 50% MVC or the conditioning TMS intensity was reduced to elicit responses of 50% of MEPmax, a significant decrease in the conditioned V?wave amplitude was observed for the triceps surae muscles, linearly correlated to the changes in MEP amplitude. The slope of this correlation, as well as the electro?mechanical efficiency, was closed to the identity line, indicating that V?wave impact at muscle level seems to be similar to the impact of cortical stimulation. All these results suggest that change in V?wave amplitude is a great index to reflect changes in cortical neural drive addressed to spinal motoneurons. PMID:25501438

Grosprêtre, Sidney; Martin, Alain

2014-01-01

184

5 Hz repetitive transcranial magnetic stimulation over the ipsilesional sensory cortex enhances motor learning after stroke  

PubMed Central

Sensory feedback is critical for motor learning, and thus to neurorehabilitation after stroke. Whether enhancing sensory feedback by applying excitatory repetitive transcranial magnetic stimulation (rTMS) over the ipsilesional primary sensory cortex (IL-S1) might enhance motor learning in chronic stroke has yet to be investigated. The present study investigated the effects of 5 Hz rTMS over IL-S1 paired with skilled motor practice on motor learning, hemiparetic cutaneous somatosensation, and motor function. Individuals with unilateral chronic stroke were pseudo-randomly divided into either Active or Sham 5 Hz rTMS groups (n = 11/group). Following stimulation, both groups practiced a Serial Tracking Task (STT) with the hemiparetic arm; this was repeated for 5 days. Performance on the STT was quantified by response time, peak velocity, and cumulative distance tracked at baseline, during the 5 days of practice, and at a no-rTMS retention test. Cutaneous somatosensation was measured using two-point discrimination. Standardized sensorimotor tests were performed to assess whether the effects might generalize to impact hemiparetic arm function. The active 5 Hz rTMS + training group demonstrated significantly greater improvements in STT performance {response time [F(1, 286.04) = 13.016, p < 0.0005], peak velocity [F(1, 285.95) = 4.111, p = 0.044], and cumulative distance [F(1, 285.92) = 4.076, p = 0.044]} and cutaneous somatosensation [F(1, 21.15) = 8.793, p = 0.007] across all sessions compared to the sham rTMS + training group. Measures of upper extremity motor function were not significantly different for either group. Our preliminary results suggest that, when paired with motor practice, 5 Hz rTMS over IL-S1 enhances motor learning related change in individuals with chronic stroke, potentially as a consequence of improved cutaneous somatosensation, however no improvement in general upper extremity function was observed. PMID:24711790

Brodie, Sonia M.; Meehan, Sean; Borich, Michael R.; Boyd, Lara A.

2014-01-01

185

Repetitive Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex Reduces Nicotine Cue Craving  

PubMed Central

Background Repetitive transcranial magnetic stimulation (rTMS) can non-invasively stimulate the brain and transiently amplify or block behaviors mediated through a region. We hypothesized that a single high-frequency rTMS session over the left dorsolateral prefrontal cortex (DLPFC) would reduce cue craving for cigarettes compared to a sham TMS session. Methods Sixteen non-treatment seeking, nicotine-dependent participants were randomized to receive either real high-frequency rTMS (10 Hz, 100% resting motor threshold, 5 second-on, 10 second-off for 15 minutes; 3000 pulses) or active sham (eSham) TMS over the DLPFC in two visits with one week between visits. The participants received cue exposure before and after rTMS and rated their craving after each block of cue presentation. Results Stimulation of the left DLFPC with real, but not sham, rTMS reduced craving significantly from baseline (64.1± 5.9 vs. 45.7±6.4, t = 2.69, p = 0.018). When compared to neutral cue craving, the effect of real TMS on cue craving was significantly greater than the effect of sham TMS (12.5 ±10.4 vs. ?9.1±10.4; t = 2.07, p = 0.049). More decreases in subjective craving induced by TMS correlated positively with higher Fagerström Test for Nicotine Dependence (FTND) score (r = 0.58, p = 0.031) and more cigarettes smoked per day (r = 0.57, p = 0.035). Conclusions One session of high frequency rTMS (10 Hz) of the left DLPFC significantly reduced subjective craving induced by smoking cues in nicotine-dependent participants. Further studies are needed to explore the use of rTMS as an aid to smoking cessation. PMID:23485014

Li, Xingbao; Hartwell, Karen J.; Owens, Max; LeMatty, Todd; Borckardt, Jeffrey; Hanlon, Colleen; Brady, Kathleen T.; George, Mark S.

2013-01-01

186

Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping  

NASA Astrophysics Data System (ADS)

Objective. This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with a lower voltage rating than prior cTMS devices. Main results. cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (\\lt 10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in ten healthy volunteers. Significance. The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool.

Peterchev, Angel V.; D?Ostilio, Kevin; Rothwell, John C.; Murphy, David L.

2014-10-01

187

Impairment of executive performance after transcranial magnetic modulation of the left dorsal frontal-striatal circuit.  

PubMed

The dorsal frontal-striatal circuit is implicated in executive functions, such as planning. The Tower of London task, a planning task, in combination with off-line low-frequency repetitive transcranial magnetic stimulation (rTMS), was used to investigate whether interfering with dorsolateral prefrontal function would modulate executive performance, mimicking dorsal frontal-striatal dysfunction as found in neuropsychiatric disorders. Eleven healthy controls (seven females; mean age 25.5 years) were entered in a cross-over design: two single-session treatments of low-frequency (1 Hz) rTMS (vs. sham rTMS) for 20 min on the left dorsolateral prefrontal cortex (DLPFC). Directly following the off-line rTMS treatment, the Tower of London task was performed during MRI measurements. The low-frequency rTMS treatment impaired performance, but only when the subjects had not performed the task before: we found a TMS condition-by-order effect, such that real TMS treatment in the first session led to significantly more errors (P = 0.032), whereas this TMS effect was not present in subjects who received real TMS in the second session. At the neural level, rTMS resulted in decreased activation during the rTMS versus sham condition in prefrontal brain regions (i.e., premotor, dorsolateral prefrontal and anterior prefrontal cortices) and visuospatial brain regions (i.e., precuneus/cuneus and inferior parietal cortex). The results show that low-frequency off-line rTMS on the DLPFC resulted in decreased task-related activations in the frontal and visuospatial regions during the performance of the Tower of London task, with a behavioral effect only when task experience is limited. PMID:22076808

van den Heuvel, Odile A; Van Gorsel, Helene C; Veltman, Dick J; Van Der Werf, Ysbrand D

2013-02-01

188

Developments in deep brain stimulation using time dependent magnetic fields  

SciTech Connect

The effect of head model complexity upon the strength of field in different brain regions for transcranial magnetic stimulation (TMS) has been investigated. Experimental measurements were used to verify the validity of magnetic field calculations and induced electric field calculations for three 3D human head models of varying complexity. Results show the inability for simplified head models to accurately determine the site of high fields that lead to neuronal stimulation and highlight the necessity for realistic head modeling for TMS applications.

Crowther, L.J.; Nlebedim, I.C.; Jiles, D.C.

2012-03-07

189

Magnetic transcranial stimulation in healthy humans: influence on the behavior of upper limb motor units.  

PubMed

Aim of the study was to analyze the characteristics of motor action potentials recruitment during magnetic trans-cranial stimulation (TCS) of the brain. Coaxial needle recordings from hand and upper limb musculature, as well as surface electrodes were employed in 20 healthy controls during magnetic TCS with regular and figure-of-8 coil in different experimental protocols including: (a) simple reaction time paradigm during which TCS at subthreshold intensity for eliciting MEPs in relaxation was delivered at various intervals between the signal to move and the onset of the voluntary EMG burst; (b) suprathreshold TCS was randomly delivered while the subject was voluntarily firing at a regular rate one 'low' and/or 'high threshold' motor unit action potential (MUAP). The pre- and post-TCS MUAPs recruitment as well as their firing rates were compared; (c) recordings with two separate needles picking up individual MUAPs from the same or from two different muscles were obtained in order to test 'synchrony' of MUAP's discharge before and after TCS; (d) the influence of the time-interval separating the last discharged MUAP from TCS was evaluated. (e) differences between simultaneous surface and depth recordings were examined. The following results were obtained. (a) The same low-amplitude MUAP which is first voluntarily recruited at the onset of the EMG burst is the one initially fired by TCS in the pre-movement period. Latency shortenings and amplitude enlargement of surface MEPs were observed with faster reaction times. Such changes were coupled to the recruitment of high-threshold MUAPs being larger in amplitude and briefer in latency than the initial one. (b) When using suprathreshold TCS, MEPs followed by silent periods were found. The SP was followed by a rebound acceleration of the MUAPs firing rate compared with pre-TCS levels. Besides rebound acceleration, new MUAPs of larger amplitude than the original (= pre-stimulus) ones were recruited beyond the voluntary control. This phenomenon-together with longer SPs- was progressively more pronounced with stronger stimuli. (c) TCS was affecting the 'synchrony' of MUAPs. (d) If the latency difference between the last pre-stimulus spike and the TCS was exceeding the half-cycle of the MUAP 'natural' firing, the SP was longer in duration. (e) SPs not preceded by MEPs were clearly present in depth recordings. Surface recordings mainly reflected the behavior of high-threshold and large MUAPs. PMID:7614001

Rossini, P M; Caramia, M D; Iani, C; Desiato, M T; Sciarretta, G; Bernardi, G

1995-04-10

190

Antidepressant-like effects of nicotine and transcranial magnetic stimulation in the olfactory bulbectomy rat model of depression  

PubMed Central

In this study, we compared the depression–like symptoms induced by olfactory bulbectomy (OBX) in the two inbred Wistar and Long Evans rat strains. We also analyzed the self-regulated oral intake of nicotine in these strains and the effect of nicotine on the depression-like symptoms of olfactory bulbectomy. Furthermore, we compared the antidepressant-like effects of nicotine on Wistar rats to those of transcranial magnetic stimulation (TMS), which has emerged as a therapeutic alternative for depression management. Our results show that Wistar rats develop depression-like symptoms, demonstrated by the forced swim test (FST), four weeks after OBX. However, we cannot observe these symptoms in bulbectomized Long Evans rats. Our results suggest that there are some innate differences in susceptibility to stress between these two rat strains. In Wistar rats, voluntary oral nicotine intake (1.2 mg/kg/day for 14 days) as well as nicotine administered as a single daily i.p. injection (1.5 mg/kg/day for 14 days) decrease the depression-like symptoms of OBX. Daily transcranial magnetic stimulation (TMS; 60 Hz and 0.7 mT for two hours per day for 14 days) also decreases depression-like symptoms but is less effective than nicotine. In conclusion, our results support the idea that there are possible innate differences for depression susceptibility and that nicotine and TMS may be useful in the treatment of this syndrome. PMID:18582540

Vieyra-Reyes, Patricia; Mineur, Yann S.; Túnez, Isaac; Vidaltamayo, Román; Picciotto, Marina R.; Drucker-Colín, René

2009-01-01

191

Inhibitory repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex modulates early affective processing.  

PubMed

The dorsolateral prefrontal cortex (dlPFC) has often been suggested as a key modulator of emotional stimulus appraisal and regulation. Therefore, in clinical trials, it is one of the most frequently targeted regions for non-invasive brain stimulation such as repetitive transcranial magnetic stimulation (rTMS). In spite of various encouraging reports that demonstrate beneficial effects of rTMS in anxiety disorders, psychophysiological studies exploring the underlying neural mechanisms are sparse. Here we investigated how inhibitory rTMS influences early affective processing when applied over the right dlPFC. Before and after rTMS or sham stimulation, subjects viewed faces with fearful or neutral expressions while whole-head magnetoencephalography (MEG) was recorded. Due to the disrupted functioning of the right dlPFC, visual processing in bilateral parietal, temporal, and occipital areas was amplified starting at around 90 ms after stimulus onset. Moreover, increased fear-specific activation was found in the right TPJ area in a time-interval between 110 and 170 ms. These neurophysiological effects were reflected in slowed reaction times for fearful, but not for neutral faces in a facial expression identification task while there was no such effect on a gender discrimination control task. Our study confirms the specific and important role of the dlPFC in regulation of early emotional attention and encourages future clinical research to use minimal invasive methods such as transcranial magnetic (TMS) or direct current stimulation (tDCS). PMID:25019678

Zwanzger, Peter; Steinberg, Christian; Rehbein, Maimu Alissa; Bröckelmann, Ann-Kathrin; Dobel, Christian; Zavorotnyy, Maxim; Domschke, Katharina; Junghöfer, Markus

2014-11-01

192

Preliminary guidelines for safe and effective use of repetitive transcranial magnetic stimulation in moderate to severe traumatic brain injury.  

PubMed

Transcranial magnetic stimulation has generated extensive interest within the traumatic brain injury (TBI) rehabilitation community, but little work has been done with repetitive protocols, which can produce prolonged changes in behavior. This is partly because of concerns about the safety of repetitive transcranial magnetic stimulation (rTMS) in subjects with TBI, particularly the risk of seizures. These risks can be minimized by careful selection of the rTMS protocol and exclusion criteria. In this article, we identify guidelines for safe use of rTMS in subjects with TBI based on a review of the literature and illustrate their application with a case study. Our subject is a 48-year-old man who sustained a severe TBI 5 years prior to beginning rTMS for the treatment of post-TBI depression. After a 4-week baseline period, we administered daily sessions of low-frequency stimulation to the right dorsolateral prefrontal cortex for 6 weeks. After stimulation, we performed monthly assessments for 3 months. The Hamilton Depression Rating Scale (HAMD) was our primary outcome measure. The stimulation was well tolerated and the patient reported no side effects. After 6 weeks of stimulation, the patient's depression was slightly improved, and these improvements continued through follow-up. At the end of follow-up, the patient's HAMD score was 49% of the average baseline score. PMID:25281871

Nielson, Dylan M; McKnight, Curtis A; Patel, Riddhi N; Kalnin, Andrew J; Mysiw, Walter J

2015-04-01

193

Safety study of 50 Hz repetitive transcranial magnetic stimulation in patients with Parkinson’s disease  

PubMed Central

Objective Repetitive transcranial magnetic stimulation (rTMS) has shown promising results in treating Parkinson’s disease (PD), but the best values for rTMS parameters are not established. 50 Hz rTMS may be superior to ? 25 Hz rTMS investigated so far. The objective of this study was to determine if 50 Hz rTMS could be delivered safely in PD patients since current safety limits are exceeded. Methods 50 Hz rTMS was applied with a circular coil on the primary motor cortex (M1). Stimulation intensity was first tested at 60% rest motor threshold [RMT] and 0.5 sec train duration and then increased in 0.5 sec steps to 2 sec, and by 10% steps to 90% RMT. Multi-channel electromyography (EMG) was recorded to control for signs of increasing time-locked EMG activity including correlates of the spread of excitation and after-discharges, or an increase of M1 excitability. Pre- and post-50 Hz rTMS assessments included EEG, Unified Parkinson Disease Rating Scale (UPDRS), Grooved Pegboard Test, Serial Reaction Time Task (SRTT), Folstein Mini-Mental Status Examination (MMSE) and Verbal Fluency to control for motor and cognitive side effects. Results Ten PD patients were investigated. Multi-channel EMG showed no signs of increased time-locked EMG activity including correlates of the spread of excitation and after-discharges, or increased M1 excitability in 9 patients. A PD patient with bi-temporal spikes in the pre-testing EEG had clinical and EMG correlates of spread of excitation at 90% RMT, but no seizure activity. Pre- and post-50 Hz assessment showed no changes. No adverse events were observed. 50 Hz rTMS was well tolerated except by one patient who wished to terminate the study due to facial muscle stimulation. Conclusion 50 Hz rTMS at an intensity of 90% RMT for 2 sec appears safe in patients with PD, but caution should be taken for patients with paroxysmal EEG activity. For this reason, comprehensive screening should include EEG before higher-frequency rTMS is applied. Significance This is the first study to investigate safety of 50 Hz rTMS in humans. PMID:19285918

Benninger, David H.; Lomarev, Mikhail; Wassermann, Eric; Lopez, Grisel; Houdayer, Elise; Fasano, Rebecca E.; Dang, Nguyet; Hallett, Mark

2009-01-01

194

Evaluation of transcranial magnetic stimulation for investigating transmission in descending motor tracts in the rat.  

PubMed

In the rat, non-invasive transcranial magnetic stimulation (TMS) has shown promise for evaluation of transmission through the spinal cord before and after repair strategies, but it is still unclear which pathways are activated by TMS. The aim of the present study was therefore to identify these pathways and to analyse the effect of TMS on spinal neurons. In 19 rats, TMS evoked responses bilaterally in forelimb (biceps brachii; BB) and hindlimb muscles (tibialis anterior). The latency and amplitude of these motor-evoked responses (MEPs) were highly variable and depended strongly on the coil position and the stimulation intensity. The most frequently observed latencies for the BB MEPs could be divided into three groups: 3-6 ms, 8-12 ms and 14-18 ms. Lesions in the dorsal columns, which destroyed the corticospinal tract at C2 and C5, significantly depressed MEPs in the mid- and high-latency ranges, but not those in the low-latency range. Lesions in the dorsolateral funiculus, which interrupted the rubrospinal tract, had no effect on MEPs in any of the latency ranges. By contrast, bilateral lesion of the reticulospinal tract and other ventro-laterally located descending pathways abolished all responses. Intracellular recordings from 54 cervical motoneurons in five rats revealed that TMS evoked excitatory postsynaptic potentials (EPSPs) at latencies that corresponded well with those of the BB MEPs. The short-latency EPSPs had rise times of around 1 ms, suggesting that they were mediated by a monosynaptic pathway. EPSPs with longer latencies had considerably longer rise times, which indicated conduction through polysynaptic pathways. Selective electrical stimulation of the pyramidal tract in the brainstem was performed in seven rats, where intracellular recordings from 70 motoneurons revealed that the earliest EPSPs and MEPs evoked by TMS were not mediated by the corticospinal tract, but by other descending motor pathways. Together, these results showed that in the rat TMS activates several descending pathways that converge on common spinal interneurons and motoneurons. Our observations confirm that the corticospinal tract has weak (and indirect) projections to cervical spinal motoneurons. PMID:17328776

Nielsen, J B; Perez, M A; Oudega, M; Enriquez-Denton, M; Aimonetti, J-M

2007-02-01

195

Low-frequency repetitive transcranial magnetic stimulation for the treatment of refractory partial epilepsy.  

PubMed

Seventeen refractory partial epilepsy patients were enrolled in an open-label study to evaluate the antiepileptic effect of low-frequency repetitive transcranial magnetic stimulation (rTMS). Seven of the patients had not obtained seizure-free status after epileptogenic focus resection surgery before they were enrolled in the study. All patients were treated with low-frequency rTMS which included 3 sessions per day (0.5 Hz, 90% RMT and 500 pulses each session) and lasted for 2 weeks. Seizure frequency, seizure days and epileptic discharges in the EEG obtained before, during and after stimulation were compared. The psychological conditions of all individual patients were evaluated with Symptom Checklist-90 (SCL-90) before and after rTMS treatment. Mean seizure frequencies per week significantly decreased in the following 4-week rTMS treatment period compared with the pretreatment period (14.09 vs. 5.63, p < 0.05, mean reduction of 60.02% in seizure frequency). Mean seizure days per week during the treatment period and the post-treatment period were lower than that of the pretreatment period (5.18 vs. 2.99 p < 0.05, mean reduction of 42.5% in seizure days). Mean epileptic discharges in the EEG decreased significantly during the treatment period compared to that of the pre-treatment period (78.60 vs. 66.09, p < 0.05, mean reduction of 15.9% in epileptic spikes discharges) in all 17 patients. Fourteen patients completed the test of Symptom Checklist-90 effectively. The scales of Global Severity Index, Depression, Anxiety, Phobic anxiety, Paranoid ideation, Psychoticism, Somatization, Obsession-compulsion, Interpersonal sensitivity, Hostility in patients decreased respectively at the post-treatment periods compared with those of the pre-treatment periods (P < 0.05). Low-frequency rTMS may have a significant antiepileptic effect in patients with refractory partial epilepsy. Additionally, our results indicate rTMS treatment can improve the psychological condition of these patients. PMID:21309441

Sun, Wei; Fu, Wei; Mao, Wei; Wang, Dequan; Wang, Yuping

2011-01-01

196

Abnormal excitability of the corticospinal pathway in patients with amyotrophic lateral sclerosis: a single motor unit study using transcranial magnetic stimulation  

Microsoft Academic Search

The pathophysiology of corticospinal tract degeneration in amyotrophic lateral sclerosis (ALS) was investigated by studying the effect of transcranial magnetic stimulation on discharge characteristics of single motor units during voluntary activation. The motor units were recorded from the first dorsal interosseus muscles of 12 patients with ALS, 14 healthy subjects, 12 patients with upper motor neuron lesions and 9 with

N. Kohara; R. Kaji; Y. Kojima; K. R. Mills; H. Fujii; T. Hamano; J. Kimura; N. Takamatsu; T. Uchiyama

1996-01-01

197

Electrical Stimulation of Rat Medial Prefrontal Cortex Enhances Forebrain Serotonin Output: Implications for Electroconvulsive Therapy and Transcranial Magnetic Stimulation in Depression  

Microsoft Academic Search

Decreased activity of the prefrontal cortex (PFC), as well as reduced serotonergic neurotransmission, is considered as a characteristic feature of major depression. The mechanism by which electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS) achieve their antidepressant effects may involve changes in PFC activity. It is, however, still unclear whether these changes are accompanied by increased synaptic availability of serotonin

Georg Juckel; Anna Mendlin; Barry L Jacobs

1999-01-01

198

Metabolic alterations in the dorsolateral prefrontal cortex after treatment with high-frequency repetitive transcranial magnetic stimulation in patients with unipolar major depression  

Microsoft Academic Search

Neuroimaging studies suggest a specific role of anterior cingulate cortex (ACC) and left dorsolateral prefrontal cortex (DLPFC) in major depression. Stimulation of the latter by means of repetitive transcranial magnetic stimulation (rTMS) as an antidepressant intervention has increasingly been investigated in the past. The objective of the present study was to examine in vivo neurochemical alterations in both brain regions

Alexander Luborzewski; Florian Schubert; Frank Seifert; Heidi Danker-Hopfe; Eva-Lotta Brakemeier; Peter Schlattmann; Ion Anghelescu; Michael Colla; Malek Bajbouj

2007-01-01

199

Topographic mapping of trans-cranial magnetic stimulation data on surface rendered MR images of the brain.  

PubMed

We present a method for the coregistration and topographic mapping of trans-cranial magnetic stimulation (TCMS) data on surface rendered images of the cortex, derived from Magnetic Resonance Images (MRI). We describe the TCMS procedure and the methods used to locate the TCM stimulation sites in the MRI coordinate system, and the algorithms needed to depict the TCMS distribution as a pseudocolour contour map on the cortical surface. The methods are validated using TCMS data from the hand (thenar) and leg (tibialis muscle). The methods used correctly depict the expected motor representations of each of these areas and we therefore propose that this technique may be used as a functional imaging tool in the investigation of cortical function in both normals and patients. PMID:9362998

Singh, K D; Hamdy, S; Aziz, Q; Thompson, D G

1997-10-01

200

Possible structural abnormality of the brainstem in unipolar depressive illness: a transcranial ultrasound and diffusion tensor magnetic resonance imaging study  

PubMed Central

Background: Most empirically derived antidepressants increase monoamine levels. The nuclei of cells synthesising these monoamines are located in the brainstem, and projection tracts such as the medial forebrain bundle reach virtually all other brain areas. Two studies of unipolar depressive illness using transcranial ultrasound have reported reduced echogenicity of the brainstem midline in unipolar depressed patients. This may be consistent with disruption of white matter tracts, including the medial forebrain bundle, and it has been suggested that the effect of such disruption could be reversed by antidepressants. Objective: To replicate these findings in a group of unipolar depressed patients and controls. Methods: Fifteen unipolar depressed patients and 15 controls were studied using transcranial ultrasound imaging and diffusion tensor magnetic resonance imaging (DT-MRI). Results: No difference in echogenicity of the brainstem midline of unipolar depressed patients was found. A possible trend (Cohen's d = 0.39) in the direction of previous studies was found. Although the echogenicity of the brainstem midline of the control group was found to be similar to previous reports, there was no reduction in the patient group. Additionally, no structural abnormality of the brainstem was identified using DT-MRI. Conclusions: While these data do not replicate the findings of previous studies reporting a significant reduction in the echogenicity of the brainstem midline in unipolar depressed patients, the ultrasound investigation indicated that there may be a trend in this direction. Given the importance of identifying the causes of depressive illness, it is important that other groups attempt similar studies. PMID:16227541

Steele, J; Bastin, M; Wardlaw, J; Ebmeier, K

2005-01-01

201

The Effect of a Series of Repetitive Transcranial Magnetic Stimulations of the Motor Cortex on Central Pain After Spinal Cord Injury  

Microsoft Academic Search

Defrin R, Grunhaus L, Zamir D, Zeilig G. The effect of a series of repetitive transcranial magnetic stimula- tions of the motor cortex on central pain after spinal cord injury. Arch Phys Med Rehabil 2007;88:1574-80. Objective: To study the analgesic effect of repetitive trans- cranial magnetic stimulation (rTMS) of the motor cortex on central pain in patients with chronic spinal

Ruth Defrin; Leon Grunhaus; Doron Zamir; Gabi Zeilig

202

Novel Therapeutic Strategies for Alcohol and Drug Addiction: Focus on GABA, Ion Channels and Transcranial Magnetic Stimulation  

PubMed Central

Drug addiction represents a major social problem where addicts and alcoholics continue to seek and take drugs despite adverse social, personal, emotional, and legal consequences. A number of pharmacological compounds have been tested in human addicts with the goal of reducing the level or frequency of intake, but these pharmacotherapies have often been of only moderate efficacy or act in a sub-population of humans. Thus, there is a tremendous need for new therapeutic interventions to treat addiction. Here, we review recent interesting studies focusing on gamma-aminobutyric acid receptors, voltage-gated ion channels, and transcranial magnetic stimulation. Some of these treatments show considerable promise to reduce addictive behaviors, or the early clinical studies or pre-clinical rationale suggest that a promising avenue could be developed. Thus, it is likely that within a decade or so, we could have important new and effective treatments to achieve the goal of reducing the burden of human addiction and alcoholism. PMID:22030714

Addolorato, Giovanni; Leggio, Lorenzo; Hopf, F Woodward; Diana, Marco; Bonci, Antonello

2012-01-01

203

Repetitive transcranial magnetic stimulation applications normalized prefrontal dysfunctions and cognitive-related metabolic profiling in aged mice.  

PubMed

Chronic high-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique that has recently received increasing interests as a therapeutic procedure for neurodegenerative diseases. To identify the metabolism mechanism underlying the improving effects of rTMS, we observed that high frequency (25Hz) rTMS for 14 days could reverse the decline of the performance of the passive avoidance task in aged mice. We further investigated the metabolite profiles in the prefrontal cortex (PFC) in those mice and found that rTMS could also reverse the metabolic abnormalities of gamma-aminobutyric acid, N-acetyl aspartic, and cholesterol levels to the degree similar to the young mice. These data suggested that the rTMS could ameliorate the age-related cognitive impairment and improving the metabolic profiles in PFC, and potentially can be used to improve cognitive decline in the elderly. PMID:24278445

Wang, Hualong; Geng, Yuan; Han, Bing; Qiang, Jing; Li, Xiaoli; Sun, Meiyu; Wang, Qian; Wang, Mingwei

2013-01-01

204

Enhancing the quality of studies using transcranial magnetic and electrical stimulation with a new computer-controlled system.  

PubMed

Transcranial magnetic (TMS) and electrical (TES) stimulation of the human brain have become useful tools in neurophysiological and neuropsychological research. Here we describe an integrated system that allows experimental control, data recording and analysis of neurophysiological and neuropsychological TMS and TES procedures (including motor thresholds, recruitment curves, intracortical inhibition and facilitation with paired pulses). The system uses a multifunction input/output board and a set of virtual instruments (VI) programmed with the Labview graphical programming language. It also includes online curve fitting of recruitment curves using the Boltzmann sigmoid function and monitoring of the preinnervation grade of the target muscle. Modules for neuropsychological stimulus presentation or faster repetitive stimulation can be easily added. This system yields more accurate data recording and analysis in a user friendly and unified environment. PMID:11000414

Kaelin-Lang, A; Cohen, L G

2000-10-15

205

Repetitive Transcranial Magnetic Stimulation Applications Normalized Prefrontal Dysfunctions and Cognitive-Related Metabolic Profiling in Aged Mice  

PubMed Central

Chronic high-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique that has recently received increasing interests as a therapeutic procedure for neurodegenerative diseases. To identify the metabolism mechanism underlying the improving effects of rTMS, we observed that high frequency (25Hz) rTMS for 14 days could reverse the decline of the performance of the passive avoidance task in aged mice. We further investigated the metabolite profiles in the prefrontal cortex (PFC) in those mice and found that rTMS could also reverse the metabolic abnormalities of gamma-aminobutyric acid, N-acetyl aspartic, and cholesterol levels to the degree similar to the young mice. These data suggested that the rTMS could ameliorate the age-related cognitive impairment and improving the metabolic profiles in PFC, and potentially can be used to improve cognitive decline in the elderly. PMID:24278445

Wang, Hualong; Geng, Yuan; Han, Bing; Qiang, Jing; Li, Xiaoli; Sun, Meiyu; Wang, Qian; Wang, Mingwei

2013-01-01

206

Listening to speech recruits specific tongue motor synergies as revealed by transcranial magnetic stimulation and tissue-Doppler ultrasound imaging.  

PubMed

The activation of listener's motor system during speech processing was first demonstrated by the enhancement of electromyographic tongue potentials as evoked by single-pulse transcranial magnetic stimulation (TMS) over tongue motor cortex. This technique is, however, technically challenging and enables only a rather coarse measurement of this motor mirroring. Here, we applied TMS to listeners' tongue motor area in association with ultrasound tissue Doppler imaging to describe fine-grained tongue kinematic synergies evoked by passive listening to speech. Subjects listened to syllables requiring different patterns of dorso-ventral and antero-posterior movements (/ki/, /ko/, /ti/, /to/). Results show that passive listening to speech sounds evokes a pattern of motor synergies mirroring those occurring during speech production. Moreover, mirror motor synergies were more evident in those subjects showing good performances in discriminating speech in noise demonstrating a role of the speech-related mirror system in feed-forward processing the speaker's ongoing motor plan. PMID:24778384

D'Ausilio, A; Maffongelli, L; Bartoli, E; Campanella, M; Ferrari, E; Berry, J; Fadiga, L

2014-01-01

207

A neuronal network model for simulating the effects of repetitive transcranial magnetic stimulation on local field potential power spectra.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) holds promise as a non-invasive therapy for the treatment of neurological disorders such as depression, schizophrenia, tinnitus, and epilepsy. Complex interdependencies between stimulus duration, frequency and intensity obscure the exact effects of rTMS stimulation on neural activity in the cortex, making evaluation of and comparison between rTMS studies difficult. To explain the influence of rTMS on neural activity (e.g. in the motor cortex), we use a neuronal network model. The results demonstrate that the model adequately explains experimentally observed short term effects of rTMS on the band power in common frequency bands used in electroencephalography (EEG). We show that the equivalent local field potential (eLFP) band power depends on stimulation intensity rather than on stimulation frequency. Additionally, our model resolves contradictions in experiments. PMID:23145082

Bey, Alina; Leue, Stefan; Wienbruch, Christian

2012-01-01

208

Metabolic changes after repetitive transcranial magnetic stimulation (rTMS) of the left prefrontal cortex: a sham-controlled proton magnetic resonance spectroscopy (1H MRS) study of healthy brain.  

PubMed

Rapid transcranial magnetic stimulation is being increasingly used in the treatment of psychiatric disorders, especially major depression. However, its mechanisms of action are still unclear. The aim of this study was to assess metabolic changes by proton magnetic resonance spectroscopy following high-frequency rapid transcranial magnetic stimulation (20 Hz), both immediately after a single session and 24 h after a series of five consecutive sessions. Twelve healthy volunteers were enrolled in a prospective single-blind, randomized study [sham (n = 5) vs. real (n = 7)]. Three brain regions were investigated (right, left dorsolateral prefrontal cortex, left anterior cingulate cortex). A single as well as a series of consecutive rapid transcranial magnetic stimulations affected cortical glutamate/glutamine levels. These effects were present not only close to the stimulation site (left dorsolateral prefrontal cortex), but also in remote (right dorsolateral prefrontal cortex, left cingulate cortex) brain regions. Remarkably, the observed changes in glutamate/glutamine levels were dependent on the pre-transcranial magnetic stimulation glutamate/glutamine concentration, i.e. the lower the pre-stimulation glutamate/glutamine level, the higher the glutamate/glutamine increase observed after short- or long-term stimulation (5 days). In general, the treatment was well tolerated and no serious side-effects were reported. Neither transient mood changes nor significant differences in the outcome of a series of neuropsychological test batteries after real or sham transcranial magnetic stimulation occurred in our experiment. In summary, these data indicate that rapid transcranial magnetic stimulation may act via stimulation of glutamatergic prefrontal neurons. PMID:12814378

Michael, Nikolaus; Gösling, Michael; Reutemann, Michael; Kersting, Annette; Heindel, Walter; Arolt, Volker; Pfleiderer, Bettina

2003-06-01

209

Temporospatial identification of language-related cortical function by a combination of transcranial magnetic stimulation and magnetoencephalography  

PubMed Central

Introduction Identification of language-related cortical functions can be carried out noninvasively by transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG), which allow for lesion-based interrogation and global temporospatial investigation of cortices, respectively. Combining these two modalities can improve the accuracy of the identification, but the relationships between them remain unclear. We compared TMS and MEG responses during the same language task to elucidate their temporospatial relationships and used the results to develop a novel method to identify language-related cortical functions. Methods Twelve healthy right-handed volunteers performed a picture-naming task during TMS and MEG. TMS was applied on the right or left inferior frontal gyrus (IFG) at five time points, and the reaction times (RTs) for naming the pictures were measured. The temporospatial oscillatory changes measured by MEG during the same task were then compared with the TMS results. Results Transcranial magnetic stimulation of the left IFG significantly lengthened RTs at 300 and 375 msec after picture presentation, whereas TMS of the right IFG did not change RTs significantly. Interestingly, the stimulus time point at which RTs increased significantly for each individual was correlated with when the low gamma event-related desynchronizations (ERDs) peaked in the left IFG. Moreover, combining the results of TMS and MEG improved the detection rate for identifying the laterality of language function. Conclusions These results suggest that the low gamma ERDs measured by MEG strongly relate to the language function of picture naming in the left IFG. Finally, we propose a novel method to identify language-related cortical functions by combining TMS and MEG. PMID:25642395

Shinshi, Misako; Yanagisawa, Takufumi; Hirata, Masayuki; Goto, Tetsu; Sugata, Hisato; Araki, Toshihiko; Okamura, Yumiko; Hasegawa, Yuka; Ihara, Aya S; Yorifuji, Shiro

2015-01-01

210

Repetitive Transcranial Magnetic Stimulation (rTMS) to Treat Social Anxiety Disorder: Case Reports and a Review of the Literature  

PubMed Central

Objectives: Social anxiety disorder (SAD) is a common and debilitating anxiety disorders. However, few studies had been dedicated to the neurobiology underlying SAD until the last decade. Rates of non-responders to standard methods of treatment remain unsatisfactorily high of approximately 25%, including SAD. Advances in our understanding of SAD could lead to new treatment strategies. A potential non invasive therapeutic option is repetitive transcranial magnetic stimulation (rTMS). Thus, we reported two cases of SAD treated with rTMS Methods: The bibliographical search used Pubmed/Medline, ISI Web of Knowledge and Scielo databases. The terms chosen for the search were: anxiety disorders, neuroimaging, repetitive transcranial magnetic stimulation. Results: In most of the studies conducted on anxiety disorders, except SAD, the right prefrontal cortex (PFC), more specifically dorsolateral PFC was stimulated, with marked results when applying high-rTMS compared with studies stimulating the opposite side. However, according to the “valence hypothesis”, anxiety disorders might be characterized by an interhemispheric imbalance associated with increased right-hemispheric activity. With regard to the two cases treated with rTMS, we found a decrease in BDI, BAI and LSAS scores from baseline to follow-up. Conclusion: We hypothesize that the application of low-rTMS over the right medial PFC (mPFC; the main structure involved in SAD circuitry) combined with high-rTMS over the left mPFC, for at least 4 weeks on consecutive weekdays, may induce a balance in brain activity, opening an attractive therapeutic option for the treatment of SAD. PMID:24278088

Paes, Flávia; Baczynski, Tathiana; Novaes, Felipe; Marinho, Tamires; Arias-Carrión, Oscar; Budde, Henning; Sack, Alexander T.; Huston, Joseph P.; Almada, Leonardo Ferreira; Carta, Mauro; Silva, Adriana Cardoso; Nardi, Antonio E.; Machado, Sergio

2013-01-01

211

Effect of 30 Hz theta burst transcranial magnetic stimulation on the primary motor cortex in children and adolescents  

PubMed Central

Fourteen healthy children (13.8 ± 2.2 years, range 10–16; M:F = 5:9) received 30 Hz intermittent theta burst transcranial magnetic stimulation (iTBS) with a stimulation intensity of 70% of resting motor threshold (RMT) with a total of 300 (iTBS300) pulses. All volunteers were free of neurologic, psychiatric and serious medical illnesses, not taking any neuropsychiatric medications, and did not have any contraindications to transcranial magnetic stimulation. Changes in the mean amplitudes of motor-evoked potentials from baseline following iTBS were expressed as a ratio and assessed from 1 to 10 min (BLOCK1) and 1–30 min (BLOCK2) using repeated-measures analysis of variance. All 14 subjects completed iTBS300 over the dominant primary motor cortex (M1) without any clinically reported adverse events. ITBS300 produced significant M1 facilitation [F(5, 65) = 3.165, p = 0.01] at BLOCK1 and trend level M1 facilitation at BLOCK2 [F(10, 129) = 1.69, p = 0.089]. Although iTBS300 (stimulation duration of 92 s at 70% RMT) delivered over M1 in typically developed children was well-tolerated and produced on average significant facilitatory changes in cortical excitability, the post-iTBS300 neurophysiologic response was variable in our small sample. ITBS300-induced changes may represent a potential neuroplastic biomarker in healthy children and those with neuro-genetic or neuro-psychiatric disorders. However, a larger sample size is needed to address safety and concerns of response variability.

Pedapati, Ernest V.; Gilbert, Donald L.; Horn, Paul S.; Huddleston, David A.; Laue, Cameron S.; Shahana, Nasrin; Wu, Steve W.

2015-01-01

212

Shaped magnetic field pulses by multi-coil repetitive transcranial magnetic stimulation (rTMS) differentially modulate anterior cingulate cortex responses and pain in volunteers and fibromyalgia patients  

PubMed Central

Background Repetitive transcranial magnetic stimulation (rTMS) has shown promise in the alleviation of acute and chronic pain by altering the activity of cortical areas involved in pain sensation. However, current single-coil rTMS technology only allows for effects in surface cortical structures. The ability to affect activity in certain deep brain structures may however, allow for a better efficacy, safety, and tolerability. This study used PET imaging to determine whether a novel multi-coil rTMS would allow for preferential targeting of the dorsal anterior cingulate cortex (dACC), an area always activated with pain, and to provide preliminary evidence as to whether this targeted approach would allow for efficacious, safe, and tolerable analgesia both in a volunteer/acute pain model as well as in fibromyalgia chronic pain patients. Methods Part 1: Different coil configurations were tested in a placebo-controlled crossover design in volunteers (N?=?16). Tonic pain was induced using a capsaicin/thermal pain model and functional brain imaging was performed by means of H215O positron emission tomography – computed tomography (PET/CT) scans. Differences in NRS pain ratings between TMS and sham treatment (NRSTMS-NRSplacebo) which were recorded each minute during the 10 minute PET scans. Part 2: 16 fibromyalgia patients were subjected to 20 multi-coil rTMS treatments over 4 weeks and effects on standard pain scales (Brief Pain Inventory, item 5, i.e. average pain NRS over the last 24 hours) were recorded. Results A single 30 minute session using one of 3 tested rTMS coil configurations operated at 1 Hz consistently produced robust reduction (mean 70% on NRS scale) in evoked pain in volunteers. In fibromyalgia patients, the 20 rTMS sessions also produced a significant pain inhibition (43% reduction in NRS pain over last 24 hours), but only when operated at 10 Hz. This degree of pain control was maintained for at least 4 weeks after the final session. Conclusion Multi-coil rTMS may be a safe and effective treatment option for acute as well as for chronic pain, such as that accompanying fibromyalgia. Further studies are necessary to optimize configurations and settings as well as to elucidate the mechanisms that lead to the long-lasting pain control produced by these treatments. PMID:23819466

2013-01-01

213

Right frontal lobe slow frequency repetitive transcranial magnetic stimulation (SF r-TMS) is an effective treatment for depression: a case-control pilot study of safety and efficacy  

Microsoft Academic Search

Major depression may result from decreased left frontal lobe function with respect to the right. Fast frequency repetitive transcranial magnetic stimulation (FF r-TMS) excites the underlying cortex whereas slow frequency repetitive transcranial magnetic stimulation (SF r-TMS) causes cortical inhibition. Left frontal FF r-TMS attenuates major depression whereas the inhibitory effects of right frontal SF r-TMS are unknown. This study tested

Daniel L Menkes; Peter Bodnar; Roderick A Ballesteros; Michael R Swenson

1999-01-01

214

Disturbance of visual search by stimulating to posterior parietal cortex in the brain using transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

In this study, we applied a transcranial magnetic stimulation (TMS) to investigate the temporal aspect for the functional processing of visual attention. Although it has been known that right posterior parietal cortex (PPC) in the brain has a role in certain visual search tasks, there is little knowledge about the temporal aspect of this area. Three visual search tasks that have different difficulties of task execution individually were carried out. These three visual search tasks are the "easy feature task," the "hard feature task," and the "conjunction task." To investigate the temporal aspect of the PPC involved in the visual search, we applied various stimulus onset asynchronies (SOAs) and measured the reaction time of the visual search. The magnetic stimulation was applied on the right PPC or the left PPC by the figure-eight coil. The results show that the reaction times of the hard feature task are longer than those of the easy feature task. When SOA=150 ms, compared with no-TMS condition, there was a significant increase in target-present reaction time when TMS pulses were applied. We considered that the right PPC was involved in the visual search at about SOA=150 ms after visual stimulus presentation. The magnetic stimulation to the right PPC disturbed the processing of the visual search. However, the magnetic stimulation to the left PPC gives no effect on the processing of the visual search.

Iramina, Keiji; Ge, Sheng; Hyodo, Akira; Hayami, Takehito; Ueno, Shoogo

2009-04-01

215

IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING, VOL. 21, NO. 3, MAY 2013 383 Noninvasive Transcranial Focal Stimulation Via  

E-print Network

including transcranial magnetic stimulation(TMS)[18]­[21]andtranscra- nial direct current stimulation (t Noninvasive Transcranial Focal Stimulation Via Tripolar Concentric Ring Electrodes Lessens Behavioral Seizure developing a noninvasive transcranial focal electrical stimulation with our novel tripolar concentric ring

Besio, Walter G.

216

Test-retest assessment of cortical activation induced by repetitive transcranial magnetic stimulation with brain atlas-guided optical topography.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is a technology that stimulates neurons with rapidly changing magnetic pulses with demonstrated therapeutic applications for various neuropsychiatric disorders. Functional near-infrared spectroscopy (fNIRS) is a suitable tool to assess rTMS-evoked brain responses without interference from the magnetic or electric fields generated by the TMS coil. We have previously reported a channel-wise study of combined rTMS/fNIRS on the motor and prefrontal cortices, showing a robust decrease of oxygenated hemoglobin concentration (?[HbO2]) at the sites of 1-Hz rTMS and the contralateral brain regions. However, the reliability of this putative clinical tool is unknown. In this study, we develop a rapid optical topography approach to spatially characterize the rTMS-evoked hemodynamic responses on a standard brain atlas. A hemispherical approximation of the brain is employed to convert the three-dimensional topography on the complex brain surface to a two-dimensional topography in the spherical coordinate system. The test-retest reliability of the combined rTMS/fNIRS is assessed using repeated measurements performed two to three days apart. The results demonstrate that the ?[HbO2] amplitudes have moderate-to-high reliability at the group level; and the spatial patterns of the topographic images have high reproducibility in size and a moderate degree of overlap at the individual level. PMID:23139044

Tian, Fenghua; Kozel, F Andrew; Yennu, Amarnath; Croarkin, Paul E; McClintock, Shawn M; Mapes, Kimberly S; Husain, Mustafa M; Liu, Hanli

2012-11-01

217

Test-retest assessment of cortical activation induced by repetitive transcranial magnetic stimulation with brain atlas-guided optical topography  

NASA Astrophysics Data System (ADS)

Repetitive transcranial magnetic stimulation (rTMS) is a technology that stimulates neurons with rapidly changing magnetic pulses with demonstrated therapeutic applications for various neuropsychiatric disorders. Functional near-infrared spectroscopy (fNIRS) is a suitable tool to assess rTMS-evoked brain responses without interference from the magnetic or electric fields generated by the TMS coil. We have previously reported a channel-wise study of combined rTMS/fNIRS on the motor and prefrontal cortices, showing a robust decrease of oxygenated hemoglobin concentration (?[HbO2]) at the sites of 1-Hz rTMS and the contralateral brain regions. However, the reliability of this putative clinical tool is unknown. In this study, we develop a rapid optical topography approach to spatially characterize the rTMS-evoked hemodynamic responses on a standard brain atlas. A hemispherical approximation of the brain is employed to convert the three-dimensional topography on the complex brain surface to a two-dimensional topography in the spherical coordinate system. The test-retest reliability of the combined rTMS/fNIRS is assessed using repeated measurements performed two to three days apart. The results demonstrate that the ?[HbO2] amplitudes have moderate-to-high reliability at the group level; and the spatial patterns of the topographic images have high reproducibility in size and a moderate degree of overlap at the individual level.

Tian, Fenghua; Kozel, F. Andrew; Yennu, Amarnath; Croarkin, Paul E.; McClintock, Shawn M.; Mapes, Kimberly S.; Husain, Mustafa M.; Liu, Hanli

2012-11-01

218

SKA Deep Polarization and Cosmic Magnetism  

E-print Network

Deep surveys with the SKA1-MID array offer for the first time the opportunity to systematically explore the polarization properties of the microJy source population. Our knowledge of the polarized sky approaching these levels is still very limited. In total intensity the population will be dominated by star-forming and normal galaxies to intermediate redshifts ($z \\sim1-2$), and low-luminosity AGN to high redshift. The polarized emission from these objects is a powerful probe of their intrinsic magnetic fields and of their magnetic environments. For redshift of order 1 and above the broad bandwidth of the mid-bands span the Faraday thick and thin regimes allowing study of the intrinsic polarization properties of these objects as well as depolarization from embedded and foreground plasmas. The deep field polarization images will provide Rotation Measures data with very high solid angle density allowing a sensitive statistical analysis of the angular variation of RM on critical arc-minute scales from a magnetic...

Taylor, A R; Akahori, Takuya; Beck, Rainer; Gaensler, Bryan; Heald, George; Johnston-Hollitt, Melanie; Langer, Mathieu; Rudnick, Lawrence; Ryu, Dongsu; Scaife, Anna; Schleicher, Dominik; Stil, Jeroen

2015-01-01

219

Behavioral/Cognitive Bihemispheric Transcranial Direct Current Stimulation  

E-print Network

Behavioral/Cognitive Bihemispheric Transcranial Direct Current Stimulation Enhances Effector these into purposeful sequences. Although transcranial direct current stimulation (tDCS) of the primary motor cortex (M1 provided by micro- stimulation in macaques (Overduin et al., 2012) and transcranial magnetic stimulation

Diedrichsen, Jörn

220

Effect of high frequency repetitive transcranial magnetic stimulation on reaction time, clinical features and cognitive functions in patients with Parkinson’s disease  

Microsoft Academic Search

The aim of the present study was to investigate the effects of one session of high-frequency repetitive transcranial magnetic\\u000a stimulation (rTMS) applied over the left dorsal premotor cortex (PMd) and left dorsolateral prefrontal cortex (DLPFC) on choice\\u000a reaction time in a noise-compatibility task, and cognitive functions in patients with Parkinson’s disease (PD). Clinical motor\\u000a symptoms of PD were assessed as

Silvie Sedlá?ková; Irena Rektorová; Hana Srovnalová; Ivan Rektor

2009-01-01

221

Treatment of auditory verbal hallucinations with transcranial magnetic stimulation in a patient with psychotic major depression: One-year follow-up  

Microsoft Academic Search

Auditory verbal hallucinations (AVH) in patients with schizophrenia can respond to repetitive transcranial magnetic stimulation (TMS). We report the therapeutic utility of rTMS in a 48-year-old patient with a 20-year history of severe depression (five suicidal gestures and previous failure of ECT) and internal AVH. First, 20 Hz rTMS to the left prefrontal cortex for 3 weeks significantly improved depression

Catarina Freitas; Chester Pearlman; Alvaro Pascual-Leone

2011-01-01

222

Treatment of auditory verbal hallucinations with transcranial magnetic stimulation in a patient with psychotic major depression: One-year follow-up  

Microsoft Academic Search

Auditory verbal hallucinations (AVH) in patients with schizophrenia can respond to repetitive transcranial magnetic stimulation (TMS). We report the therapeutic utility of rTMS in a 48-year-old patient with a 20-year history of severe depression (five suicidal gestures and previous failure of ECT) and internal AVH. First, 20 Hz rTMS to the left prefrontal cortex for 3 weeks significantly improved depression

Catarina Freitas; Chester Pearlman; Alvaro Pascual-Leone

2012-01-01

223

Frequency dependence of antidepressant response to left prefrontal repetitive transcranial magnetic stimulation (rTMS) as a function of baseline cerebral glucose metabolism  

Microsoft Academic Search

Background: Recent studies suggest that both high frequency (10–20 Hz) and low frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) have an antidepressant effect in some individuals. Electrophysiologic data indicate that high frequency rTMS enhances neuronal firing efficacy and that low frequency rTMS has the opposite effect.Methods: We investigated the antidepressant effects of 10 daily left prefrontal 1 Hz versus

Timothy A. Kimbrell; John T. Little; Robert T. Dunn; Mark A. Frye; Benjamin D. Greenberg; Eric M. Wassermann; Jennifer D. Repella; Aimee L. Danielson; Mark W. Willis; Brenda E. Benson; Andrew M. Speer; Elizabeth Osuch; Mark S. George; Robert M. Post

1999-01-01

224

Decrease of middle cerebral artery blood flow velocity after low-frequency repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex  

Microsoft Academic Search

Objectives: Repetitive transcranial magnetic stimulation (rTMS) has been tried therapeutically in a variety of neuropsychiatric disorders. Both, inhibition and activation of cortical areas may be achieved using different stimulation parameters. Using low-frequency rTMS (0.9Hz), inhibition of cortical areas can be observed.Methods: In the present study, 38 right-handed, healthy, normotensive subjects (aged 21–50 years, mean 30.2 years, SD=4.9; 17 women) were

Jens D. Rollnik; Ariane Düsterhöft; Jan Däuper; Andon Kossev; Karin Weissenborn; Reinhard Dengler

2002-01-01

225

Repetitive Transcranial Magnetic Stimulation (rTMS) in the Management of Alcohol Dependence and other Substance Abuse Disorders – Emerging Data and Clinical Relevance  

PubMed Central

Repetitive transcranial magnetic stimulation (rTMS) has been used widely in various psychiatric disorders like depression and schizophrenia. There have been some reports of its usefulness in alcohol dependence and substance use disorders. The present paper reviews the studies done using rTMS in substance use disorders including alcohol and nicotine dependence. Various studies done have been reviewed including the proposed mechanisms of action are outlined with the future research needs and need for further clinical data PMID:25337357

Sousa, Avinash De

2013-01-01

226

The relationship between brain oscillatory activity and therapeutic effectiveness of transcranial magnetic stimulation in the treatment of major depressive disorder  

PubMed Central

Major depressive disorder (MDD) is marked by disturbances in brain functional connectivity. This connectivity is modulated by rhythmic oscillations of brain electrical activity, which enable coordinated functions across brain regions. Oscillatory activity plays a central role in regulating thinking and memory, mood, cerebral blood flow, and neurotransmitter levels, and restoration of normal oscillatory patterns is associated with effective treatment of MDD. Repetitive transcranial magnetic stimulation (rTMS) is a robust treatment for MDD, but the mechanism of action (MOA) of its benefits for mood disorders remains incompletely understood. Benefits of rTMS have been tied to enhanced neuroplasticity in specific brain pathways. We summarize here the evidence that rTMS entrains and resets thalamocortical oscillators, normalizes regulation and facilitates reemergence of intrinsic cerebral rhythms, and through this mechanism restores normal brain function. This entrainment and resetting may be a critical step in engendering neuroplastic changes and the antidepressant effects of rTMS. It may be possible to modify the method of rTMS administration to enhance this MOA and achieve better antidepressant effectiveness. We propose that rTMS can be administered: (1) synchronized to a patient's individual alpha frequency (IAF), or synchronized rTMS (sTMS); (2) as a low magnetic field strength sinusoidal waveform; and, (3) broadly to multiple brain areas simultaneously. We present here the theory and evidence indicating that these modifications could enhance the therapeutic effectiveness of rTMS for the treatment of MDD. PMID:23550274

Leuchter, Andrew F.; Cook, Ian A.; Jin, Yi; Phillips, Bill

2013-01-01

227

The relationship between brain oscillatory activity and therapeutic effectiveness of transcranial magnetic stimulation in the treatment of major depressive disorder.  

PubMed

Major depressive disorder (MDD) is marked by disturbances in brain functional connectivity. This connectivity is modulated by rhythmic oscillations of brain electrical activity, which enable coordinated functions across brain regions. Oscillatory activity plays a central role in regulating thinking and memory, mood, cerebral blood flow, and neurotransmitter levels, and restoration of normal oscillatory patterns is associated with effective treatment of MDD. Repetitive transcranial magnetic stimulation (rTMS) is a robust treatment for MDD, but the mechanism of action (MOA) of its benefits for mood disorders remains incompletely understood. Benefits of rTMS have been tied to enhanced neuroplasticity in specific brain pathways. We summarize here the evidence that rTMS entrains and resets thalamocortical oscillators, normalizes regulation and facilitates reemergence of intrinsic cerebral rhythms, and through this mechanism restores normal brain function. This entrainment and resetting may be a critical step in engendering neuroplastic changes and the antidepressant effects of rTMS. It may be possible to modify the method of rTMS administration to enhance this MOA and achieve better antidepressant effectiveness. We propose that rTMS can be administered: (1) synchronized to a patient's individual alpha frequency (IAF), or synchronized rTMS (sTMS); (2) as a low magnetic field strength sinusoidal waveform; and, (3) broadly to multiple brain areas simultaneously. We present here the theory and evidence indicating that these modifications could enhance the therapeutic effectiveness of rTMS for the treatment of MDD. PMID:23550274

Leuchter, Andrew F; Cook, Ian A; Jin, Yi; Phillips, Bill

2013-01-01

228

Relationship between transcranial magnetic stimulation measures of intracortical inhibition and spectroscopy measures of GABA and glutamate+glutamine  

PubMed Central

Transcranial magnetic stimulation (TMS) can provide an index of intracortical excitability/inhibition balance. However, the neurochemical substrate of these measures remains unclear. Pharmacological studies suggest the involvement of GABAA and GABAB receptors in TMS protocols aimed at measuring intracortical inhibition, but this link remains inferential. Proton magnetic resonance spectroscopy (1H-MRS) permits measurement of GABA and glutamate + glutamine (Glx) concentrations in the human brain and might help in the direct empirical assessment of the relationship between TMS inhibitory measures and neurotransmitter concentrations. In the present study, MRS-derived relative concentrations of GABA and Glx measured in the left M1 of healthy participants were correlated with TMS measures of intracortical inhibition. Glx levels were found to correlate positively with TMS-induced silent period duration, whereas no correlation was found between GABA concentration and TMS measures. The present data demonstrate that specific TMS measures of intracortical inhibition are linked to shifts in cortical Glx, rather than GABA neurotransmitter levels. Glutamate might specifically interact with GABAB receptors, where higher MRS-derived Glx concentrations seem to be linked to higher levels of receptor activity. PMID:23221412

Tremblay, Sara; Beaulé, Vincent; Proulx, Sébastien; de Beaumont, Louis; Marja?ska, Ma?gorzata; Doyon, Julien; Pascual-Leone, Alvaro; Lassonde, Maryse

2013-01-01

229

Blood flow and oxygenation changes due to low-frequency repetitive transcranial magnetic stimulation of the cerebral cortex  

NASA Astrophysics Data System (ADS)

Transcranial magnetic stimulation (TMS) modulates processing in the human brain and is therefore of interest as a treatment modality for neurologic conditions. During TMS administration, an electric current passing through a coil on the scalp creates a rapidly varying magnetic field that induces currents in the cerebral cortex. The effects of low-frequency (1 Hz), repetitive TMS (rTMS) on motor cortex cerebral blood flow (CBF) and tissue oxygenation in seven healthy adults, during/after 20 min stimulation, is reported. Noninvasive optical methods are employed: diffuse correlation spectroscopy (DCS) for blood flow and diffuse optical spectroscopy (DOS) for hemoglobin concentrations. A significant increase in median CBF (33%) on the side ipsilateral to stimulation was observed during rTMS and persisted after discontinuation. The measured hemodynamic parameter variations enabled computation of relative changes in cerebral metabolic rate of oxygen consumption during rTMS, which increased significantly (28%) in the stimulated hemisphere. By contrast, hemodynamic changes from baseline were not observed contralateral to rTMS administration (all parameters, p>0.29). In total, these findings provide new information about hemodynamic/metabolic responses to low-frequency rTMS and, importantly, demonstrate the feasibility of DCS/DOS for noninvasive monitoring of TMS-induced physiologic effects.

Mesquita, Rickson C.; Faseyitan, Olufunsho K.; Turkeltaub, Peter E.; Buckley, Erin M.; Thomas, Amy; Kim, Meeri N.; Durduran, Turgut; Greenberg, Joel H.; Detre, John A.; Yodh, Arjun G.; Hamilton, Roy H.

2013-06-01

230

Movement and afferent representations in human motor areas: a simultaneous neuroimaging and transcranial magnetic/peripheral nerve-stimulation study  

PubMed Central

Neuroimaging combined with transcranial magnetic stimulation (TMS) to primary motor cortex (M1) is an emerging technique that can examine motor-system functionality through evoked activity. However, because sensory afferents from twitching muscles are widely represented in motor areas the amount of evoked activity directly resulting from TMS remains unclear. We delivered suprathreshold TMS to left M1 or gave electrical right median nerve stimulation (MNS) in 18 healthy volunteers while simultaneously conducting functional magnetic resonance imaging and monitoring with electromyography (EMG). We examined in detail the localization of TMS-, muscle afferent- and superficial afferent-induced activity in M1 subdivisions. Muscle afferent- and TMS-evoked activity occurred mainly in rostral M1, while superficial afferents generated a slightly different activation distribution. In 12 participants who yielded quantifiable EMG, differences in brain activity ascribed to differences in movement-size were adjusted using integrated information from the EMGs. Sensory components only explained 10–20% of the suprathreshold TMS-induced activity, indicating that locally and remotely evoked activity in motor areas mostly resulted from the recruitment of neural and synaptic activity. The present study appears to justify the use of fMRI combined with suprathreshold TMS to M1 for evoked motor network imaging. PMID:24062660

Shitara, H.; Shinozaki, T.; Takagishi, K.; Honda, M.; Hanakawa, T.

2013-01-01

231

Extended Remediation of Sleep Deprived-Induced Working Memory Deficits Using fMRI-guided Transcranial Magnetic Stimulation  

PubMed Central

Study Objectives: We attempted to prevent the development of working memory (WM) impairments caused by sleep deprivation using fMRI-guided repetitive transcranial magnetic stimulation (rTMS). Novel aspects of our fMRI-guided rTMS paradigm included the use of sophisticated covariance methods to identify functional networks in imaging data, and the use of fMRI-targeted rTMS concurrent with task performance to modulate plasticity effects over a longer term. Design: Between-groups mixed model. Setting: TMS, MRI, and sleep laboratory study. Participants: 27 subjects (13 receiving Active rTMS, and 14 Sham) completed the sleep deprivation protocol, with another 21 (10 Active, 11 Sham) non-sleep deprived subjects run in a second experiment. Interventions: Our previous covariance analysis had identified a network, including occipital cortex, which demonstrated individual differences in resilience to the deleterious effects of sleep deprivation on WM performance. Five Hz rTMS was applied to left lateral occipital cortex while subjects performed a WM task during 4 sessions over the course of 2 days of total sleep deprivation. Measurements and Results: At the end of the sleep deprivation period, Sham sleep deprived subjects exhibited degraded performance in the WM task. In contrast, those receiving Active rTMS did not show the slowing and lapsing typical in sleep deprivation, and instead performed similarly to non- sleep deprived subjects. Importantly, the Active sleep deprivation group showed rTMS-induced facilitation of WM performance a full 18 hours after the last rTMS session. Conclusions: Over the course of sleep deprivation, these results indicate that rTMS applied concurrently with WM task performance affected neural circuitry involved in WM to prevent its full impact. Citation: Luber B; Steffener J; Tucker A; Habeck C; Peterchev AV; Deng ZD; Basner RC; Stern Y; Lisanby SH. Extended remediation of sleep deprived-induced working memory deficits using fMRI-guided transcranial magnetic stimulation. SLEEP 2013;36(6):857-871. PMID:23729929

Luber, Bruce; Steffener, Jason; Tucker, Adrienne; Habeck, Christian; Peterchev, Angel V.; Deng, Zhi-De; Basner, Robert C.; Stern, Yaakov; Lisanby, Sarah H.

2013-01-01

232

Impairment of callosal and corticospinal system function in adolescents with early-treated phenylketonuria: a transcranial magnetic stimulation study.  

PubMed

The transcranial activation and the conduction properties of corticospinal and callosal neurons were investigated in 12 early-treated adolescents (aged 17.3, SD 3.5 years; range 14-27 years) with phenylketonuria (PKU) by focal transcranial magnetic stimulation (fTMS) of the motor cortex. The patients had no functionally relevant motor disturbances in daily life or on clinical testing. Corticospinally mediated excitatory (response thresholds, amplitudes, central motor latencies) and inhibitory [duration of postexcitatory inhibition (PI)] effects of fTMS were investigated in contralateral hand muscles. Transcallosal inhibition (TI) (onset latency, duration, transcallosal latency) of tonic electromyographic (EMG) activity was tested in ipsilateral muscles. Peripheral motor latencies were determined for responses elicited by magnetic stimulation over cervical nerve roots. Ten normal subjects served as controls. Since in all PKU patients, central and peripheral motor latencies were normal, no neurophysiological indication of a demyelination of corticospinal or peripheral motor fibres was found. However, cortical thresholds of corticospinally mediated responses were increased (52.1, SD 11.6% versus 35.0, SD 7.4% of maximum stimulator output; P < 0.05; n = 24 hands) and their amplitudes reduced (2.9, SD 1.4 mV versus 6.1, SD 1.5 mV, P < 0.05). The duration of PI was shortened (132, SD 53 ms versus 178, SD 57 ms; P < 0.05). TI was absent in 37.5% of the investigated hands or tended to be weak. When TI was present, its onset latencies (38.0, SD 3.6 ms versus 34.7, SD 3.3 ms) and transcallosal latencies were prolonged (18.5, SD 3.8 ms versus 14.8, SD 3.2 ms), while its duration was normal. These abnormal excitatory and inhibitory effects of fTMS suggest a reduced susceptibility of cortical excitatory and inhibitory neuronal structures compatible with a loss of neurons or a rarefication of their dendrites. PMID:9987710

Röricht, S; Meyer, B U; Irlbacher, K; Ludolph, A C

1999-01-01

233

Safe use of repetitive transcranial magnetic stimulation in patients with implanted vagus nerve stimulators.  

PubMed

Vagus nerve stimulation (VNS) and repetitive transcranial stimulation (rTMS) devices are FDA cleared for therapeutic use in treatment resistant depression. Since VNS systems have ferromagnetic components and large-scale safety testing has not been done, the implanted VNS device is considered a contraindication for rTMS therapy. This contraindication should not be considered absolute, as VNS components typically lie outside the electromagnetic field generated by an rTMS treatment coil. We solicited information from clinicians at several academic medical centers through an informal survey about their use of rTMS for depressed patients with implanted VNS systems, and reviewed relevant safety issues with one rTMS device manufacturer. rTMS clinical practices may use special consent procedures and take additional precautions to enhance safety in these situations. Specific recommendations are provided for minimizing risks (heating or movement of VNS components and unintended change in VNS stimulation parameters) when delivering rTMS to patients with implanted VNS systems. PMID:24794163

Philip, Noah S; Carpenter, S Louisa; Carpenter, Linda L

2014-01-01

234

Venus Deep Nightside Magnetic Fields Revisited  

NASA Astrophysics Data System (ADS)

We reexamined the near-Venus deep nightside magnetic fields observed by the Pioneer Venus Orbiter(PVO) over two decades ago. This analysis was in part inspired by recent discussions of the possibilities of identifying a weak planetary dynamo or remanent magnetic field, and in part by the availability of numerical simulations of weak field plasma interactions using the BATS-R-US MHD code. The data were first scrutinized for statistically significant regions of radial field in the near-midnight low altitude wake from the prime mission periapsis of ~150km up to about 450 km. Radial field 'maps' were constructed for a range of altitudes in both solar wind interaction and planetary geographical coordinate systems. The results suggested the presence of weak radial fields above ~250km that show a persistent North-South sign bias. This behavior is not seen at the lowest altitudes probed, and is present regardless of the interplanetary magnetic field sector. The MHD simulations provided basic pictures of what might be expected for a hypothetical planet with a weak but still detectable dipole field that is comparable to the solar wind interaction-related draped interplanetary field. These show similar tendencies, illustrating that models are essential to the interpretation of potential weak intrinsic field signatures at planets such as Venus. Further modeling specific to Venus is needed to make further progress.

Villarreal, M. N.; Luhmann, J. G.; Ma, Y.; Russell, C. T.; Wei, H.; Zhang, T.

2011-12-01

235

Transcranial Magnetic Stimulation Reveals Dissociable Mechanisms for Global Versus Selective Corticomotor Suppression Underlying the Stopping of Action  

PubMed Central

Stopping an initiated response is an essential function, investigated in many studies with go/no-go and stop-signal paradigms. These standard tests require rapid action cancellation. This appears to be achieved by a suppression mechanism that has “global” effects on corticomotor excitability (i.e., affecting task-irrelevant muscles). By contrast, stopping action in everyday life may require selectivity (i.e., targeting a specific response tendency without affecting concurrent action). We hypothesized that while standard stopping engages global suppression, behaviorally selective stopping engages a selective suppression mechanism. Accordingly, we measured corticomotor excitability of the task-irrelevant leg using transcranial magnetic stimulation while subjects stopped the hand. Experiment 1 showed that for standard (i.e., nonselective) stopping, the task-irrelevant leg was suppressed. Experiment 2 showed that for behaviorally selective stopping, there was no mean leg suppression. Experiment 3 directly compared behaviorally nonselective and selective stopping. Leg suppression occurred only in the behaviorally nonselective condition. These results argue that global and selective suppression mechanisms are dissociable. Participants may use a global suppression mechanism when speed is stressed; however, they may recruit a more selective suppression mechanism when selective stopping is behaviorally necessary and preparatory information is available. We predict that different fronto–basal–ganglia pathways underpin these different suppression mechanisms. PMID:21666129

Majid, D. S. Adnan; Cai, Weidong; George, Jobi S.; Verbruggen, Frederick

2012-01-01

236

Does Inhibitory Repetitive Transcranial Magnetic Stimulation Augment Functional Task Practice to Improve Arm Recovery in Chronic Stroke?  

PubMed Central

Introduction. Restoration of upper extremity (UE) functional use remains a challenge for individuals following stroke. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive modality that modulates cortical excitability and is being explored as a means to potentially ameliorate these deficits. The purpose of this study was to evaluate, in the presence of chronic stroke, the effects of low-frequency rTMS to the contralesional hemisphere as an adjuvant to functional task practice (FTP), to improve UE functional ability. Methods. Twenty-two individuals with chronic stroke and subsequent moderate UE deficits were randomized to receive 16 sessions (4 times/week for 4 weeks) of either real-rTMS or sham-rTMS followed by 1-hour of paretic UE FTP. Results. No differences in UE outcomes were revealed between the real-rTMS and sham-rTMS intervention groups. After adjusting for baseline differences, no differences were revealed in contralesional cortical excitability postintervention. In a secondary analysis, data pooled across both groups revealed small, but statistically significant, improvements in UE behavioral measures. Conclusions. rTMS did not augment changes in UE motor ability in this population of individuals with chronic stroke. The chronicity of our participant cohort and their degree of UE motor impairment may have contributed to inability to produce marked effects using rTMS. PMID:25197611

McGuirk, Theresa E.; Triggs, William J.

2014-01-01

237

Bilateral Repetitive Transcranial Magnetic Stimulation for Auditory Hallucinations in Patients with Schizophrenia: A Randomized Controlled, Cross-over Study  

PubMed Central

Objective A randomized double-blind cross-over trial was conducted in patients with persistent auditory hallucinations (AHs) to investigate whether bilateral repetitive transcranial magnetic stimulation (rTMS) at the temporoparietal area or Broca's area is more effective at high- or low-frequencies compared to a sham condition. Methods Twenty three patients with persistent AHs who remained stable on the same medication for 2 months were enrolled. They were randomized to one of four conditions: low-frequency (1 Hz)-rTMS to the temporoparietal area (L-TP), high-frequency (20 Hz)-rTMS to the temporoparietal area (H-TP), high-frequency (20 Hz)-rTMS to Broca's area (H-B), or sham. Results All the four rTMS conditions resulted in significant decrease in the scores under the auditory hallucination rating scale and hallucination change scale over time. However, there were no significant treatment effects or interaction between time and treatment, suggesting no superior effects of the new paradigms over the sham condition. Conclusion Our findings suggest that bilateral rTMS at the temporoparietal area or Broca's area with high- or low-frequency does not produce superior effects in reducing AHs compared to sham stimulation. PMID:25598827

Kim, Eun-Ji; Yeo, Seonguk; Hwang, Inho; Park, Jong-Il; Cui, Yin; Jin, Hong-Mei; Kim, Hyung Tae; Hwang, Tae-Young

2014-01-01

238

Impact of Repetitive Transcranial Magnetic Stimulation on Post-Stroke Dysmnesia and the Role of BDNF Val66Met SNP  

PubMed Central

Background Little is known about the effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) on dysmnesia and the impact of brain nucleotide neurotrophic factor (BDNF) Val66Met single-nucleotide polymorphism (SNP). This study investigated the impact of low-frequency rTMS on post-stroke dysmnesia and the impact of BDNF Val66Met SNP. Material/Methods Forty patients with post-stroke dysmnesia were prospectively randomized into the rTMS and sham groups. BDNF Val66Met SNP was determined using restriction fragment length polymorphism. Montreal Cognitive Assessment (MoCA), Loewenstein Occupational Therapy of Cognitive Assessment (LOTCA), and Rivermead Behavior Memory Test (RBMT) scores, as well as plasma BDNF concentrations, were measured at baseline and at 3 days and 2 months post-treatment. Results MoCA, LOTCA, and RBMT scores were higher after rTMS. Three days after treatment, BDNF decreased in the rTMS group but it increased in the sham group (P<0.05). Two months after treatment, RMBT scores in the rTMS group were higher than in the sham group, but not MoCA and LOTCA scores. Conclusions Low-frequency rTMS may improve after-stoke memory through various pathways, which may involve polymorphisms and several neural genes, but not through an increase in BDNF levels. PMID:25770310

Lu, Haitao; Zhang, Tong; Wen, Mei; Sun, Li

2015-01-01

239

Repetitive transcranial magnetic stimulation over the orbitofrontal cortex for obsessive-compulsive disorder: a double-blind, crossover study  

PubMed Central

This pilot study was designed to assess the efficacy of low-frequency repetitive transcranial magnetic stimulation (rTMS) over the right orbitofrontal cortex (OFC) by means of a double-cone coil in patients suffering from obsessive-compulsive disorder. We hypothesized that low-frequency stimulation of the OFC would lead to a reduction in clinical symptoms, as measured on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). A randomized, double-blind, crossover design was implemented with two 1-week treatment periods (active stimulation versus sham stimulation) separated by a 1-month washout period. Concomitantly, a subgroup of patients underwent a positron emission tomography (PET) scan after each stimulation sequence. Statistical analyses compared the Y-BOCS scores at the end of each period. At day 7, we observed a significant decrease from baseline in the Y-BOCS scores, after both active (P<0.01) and sham stimulation (P=0.02). This decrease tended to be larger after active stimulation than after sham stimulation: ?6 (?29, 0) points versus ?2 (?20, 4) points (P=0.07). Active versus sham PET scan contrasts showed that stimulation was related to a bilateral decrease in the metabolism of the OFC. The OFC should definitely be regarded as a key neuroanatomical target for rTMS, as it is easier to reach than either the striatum or the subthalamic nucleus, structures favored in neurosurgical approaches. PMID:25203167

Nauczyciel, C; Le Jeune, F; Naudet, F; Douabin, S; Esquevin, A; Vérin, M; Dondaine, T; Robert, G; Drapier, D; Millet, B

2014-01-01

240

Novel ‘hunting’ method using transcranial magnetic stimulation over parietal cortex disrupts visuospatial sensitivity in relation to motor thresholds  

PubMed Central

There is considerable inter-study and inter-individual variation in the scalp location of parietal sites where transcranial magnetic stimulation (TMS) may modulate visuospatial behaviours (see Ryan, Bonilha, & Jackson 2006); and no clear consensus on methods for identifying such sites. Here we introduce a novel TMS “hunting paradigm” that allows rapid, reliable identification of a site over right anterior intraparietal sulcus (IPS), where short trains (at 10 Hz for 0.5s) of TMS disrupt performance of a task in which subjects judge the presence or absence of a small peripheral gap (at 14 degrees eccentricity), on one or other (known) side of an extended (29 degrees) horizontal line centred on fixation. Signal detection analysis confirmed that TMS at this site reduced sensitivity (d’) for gap targets in the left visual hemifield. A further experiment showed that the same right-parietal TMS increased sensitivity instead for gaps in the right hemifield. Comparing TMS across a grid of scalp locations around the identified ‘hotspot’ confirmed the spatial specificity. Assessment of the TMS intensity required to produce the phenomena found this was linearly related to individuals’ resting motor TMS threshold over hand M1. Our approach provides a systematic new way to identify an effective site and intensity in individuals, at which TMS over right parietal cortex reliably changes visuospatial sensitivity. PMID:19651149

Oliver, R; Bjoertomt, O; Driver, J; Greenwood, R; Rothwell, J

2010-01-01

241

Role of the posterior temporal lobe during language tasks: a virtual lesion study using repetitive transcranial magnetic stimulation.  

PubMed

Functional brain imaging studies have suggested that the superior temporal gyrus (STG) and the middle temporal gyrus (MTG) are involved in phonological and lexical-semantic processing, respectively. However, the precise role of the posterior temporal lobe is not fully understood. To clarify the functional relevance of the left posterior STG and MTG during language processing, we used neuronavigation-guided repetitive transcranial magnetic stimulation (rTMS). The reaction times and error rates for 12 healthy volunteers performing auditory repetition and lexical-semantic decision tasks were compared before and during rTMS stimulation. We applied 1?Hz rTMS over the left posterior STG or MTG or sham stimulation for 10?min in a random order. Stimulation of the left posterior MTG significantly slowed the response time for the lexical-semantic decision task from 478.9±56.5 to 583.1±80.0?ms. However, stimulation over the left posterior STG or MTG did not affect the response time or the error rate for the auditory repetition task. Our results suggest that the left posterior MTG might be involved in lexical decision making. Neuronavigation-guided rTMS virtual lesion studies could help determine the functional roles of specific brain areas in language processing, and our findings provide new evidence supporting the use of neuromodulation through rTMS for patients with aphasia. PMID:25714425

Choi, Yoon-Hee; Park, Hae Kyung; Paik, Nam-Jong

2015-04-15

242

Transcranial magnetic stimulation as an investigative tool for motor dysfunction and recovery in stroke: an overview for neurorehabilitation clinicians  

PubMed Central

Rationale An improved understanding of motor dysfunction and recovery after stroke has important clinical implications that may lead to the design of more effective rehabilitation strategies for patients with hemiparesis. Scope Transcranial magnetic stimulation (TMS) is a safe and painless tool that has been used in conjunction with other existing diagnostic tools to investigate motor pathophysiology in stroke patients. Since TMS emerged over two decades ago, its application in clinical and basic neuroscience has expanded worldwide. TMS can quantify the corticomotor excitability properties of clinically affected and unaffected muscles, and probe local cortical networks, as well as remote but functionally related areas. This provides novel insight into the physiology of neural circuits underlying motor dysfunction, and brain reorganization during the motor recovery process. This important tool needs to be used with caution by clinical investigators, its limitations need to be understood and the results should be interpreted along with clinical evaluation in this patient population. Summary In this review, we provide an overview of the rationale, implementation and limitations of TMS to study stroke motor physiology. This knowledge may be useful to guide future rehabilitation treatments by assessing and promoting functional plasticity. PMID:22624621

Cortes, Mar; Black-Schaffer, Randie M; Edwards, Dylan J

2012-01-01

243

The Perceived Position of Moving Objects: Transcranial Magnetic Stimulation of Area MT+ Reduces the Flash-Lag Effect  

PubMed Central

How does the visual system assign the perceived position of a moving object? This question is surprisingly complex, since sluggish responses of photoreceptors and transmission delays along the visual pathway mean that visual cortex does not have immediate information about a moving object's position. In the flash-lag effect (FLE), a moving object is perceived ahead of an aligned flash. Psychophysical work on this illusion has inspired models for visual localization of moving objects. However, little is known about the underlying neural mechanisms. Here, we investigated the role of neural activity in areas MT+ and V1/V2 in localizing moving objects. Using short trains of repetitive Transcranial Magnetic Stimulation (TMS) or single pulses at different time points, we measured the influence of TMS on the perceived location of a moving object. We found that TMS delivered to MT+ significantly reduced the FLE; single pulse timings revealed a broad temporal tuning with maximum effect for TMS pulses, 200 ms after the flash. Stimulation of V1/V2 did not significantly influence perceived position. Our results demonstrate that area MT+ contributes to the perceptual localization of moving objects and is involved in the integration of position information over a long time window. PMID:22302116

Ward, Jamie; Nijhawan, Romi; Whitney, David

2013-01-01

244

Disrupted Central Inhibition after Transcranial Magnetic Stimulation of Motor Cortex in Schizophrenia with Long-Term Antipsychotic Treatment  

PubMed Central

Aims. Schizophrenia is a neuropsychiatric disorder associated with mental and motor disturbances. We aimed to investigate motor control, especially central silent period (CSP) in subjects with schizophrenia (n = 11) on long-term antipsychotic treatment compared to healthy controls (n = 9). Methods. Latency and duration of motor evoked potentials (MEPs) and CSPs were measured with the help of single pulse transcranial magnetic stimulation (TMS) and intramuscular electrodes. After stimulation of the dominant and nondominant motor cortex of abductor digiti minimi (ADM) and tibialis anterior (TA) muscle areas, respective responses were measured on the contralateral side. Results. MEPs did not differ significantly between the groups. Multiple CSPs were found predominantly in subjects with schizophrenia, which showed a higher number of CSPs in the dominant ADM and the longest summarized duration of CSPs in the nondominant ADM (P < 0.05) compared to controls. Conclusions. There were multiple CSPs predominantly in the upper extremities and in the dominant body side in subjects with schizophrenia. Behind multiple CSPs may lie an impaired regulation of excitatory or inhibitory neurotransmitter systems in central motor pathways. Further research is needed to clarify the role of the intramuscular recording methods and the effect of antipsychotics on the results. PMID:23738224

Lauerma, Hannu; Kähkönen, Seppo

2013-01-01

245

Suppression of EMG activity by subthreshold paired-pulse transcranial magnetic stimulation to the leg motor cortex.  

PubMed

Cortical activity driving a voluntary muscle contraction is inhibited by very low-intensity transcranial magnetic stimulation (TMS) and is reflected in the suppression of the average rectified EMG. This approach offers a method to test the contribution of cortical neurons actively involved in a motor task, but requires a large number of stimuli (approximately 100) to suitably depress the average EMG. Here, we investigated whether two pulses of subthreshold TMS at interstimulus intervals (ISIs) ranging between 1 and 12 ms could enhance the amount of EMG suppression in the tibialis anterior muscle compared to a single pulse. Pairs of subthreshold TMS at an ISI of 7 ms produced the maximum EMG suppression that was 42% more than the inhibition elicited using a single pulse. In addition, the signal-to-noise ratio of the TMS-induced suppression was further increased by a second pulse, delivered 7 ms later. The reduction in the EMG at the 7 ms paired-pulse interval occurred without any short-latency excitation suggesting that the two stimuli increased the activation of cortical inhibitory neurons. Subthreshold paired-pulse TMS at ISIs of 1-3 ms was prone to EMG excitation in the period that immediately preceded the inhibition and is consistent with the recruitment of short-interval intracortical facilitation (SICF). We propose that pairs of subthreshold TMS outside the range of SICF with an inter-pulse interval of 7 ms is optimal to inhibit ongoing cortical activity during human motor movement. PMID:19183971

Roy, François D

2009-03-01

246

Impact of Repetitive Transcranial Magnetic Stimulation on Post-Stroke Dysmnesia and the Role of BDNF Val66Met SNP.  

PubMed

Background Little is known about the effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) on dysmnesia and the impact of brain nucleotide neurotrophic factor (BDNF) Val66Met single-nucleotide polymorphism (SNP). This study investigated the impact of low-frequency rTMS on post-stroke dysmnesia and the impact of BDNF Val66Met SNP. Material and Methods Forty patients with post-stroke dysmnesia were prospectively randomized into the rTMS and sham groups. BDNF Val66Met SNP was determined using restriction fragment length polymorphism. Montreal Cognitive Assessment (MoCA), Loewenstein Occupational Therapy of Cognitive Assessment (LOTCA), and Rivermead Behavior Memory Test (RBMT) scores, as well as plasma BDNF concentrations, were measured at baseline and at 3 days and 2 months post-treatment. Results MoCA, LOTCA, and RBMT scores were higher after rTMS. Three days after treatment, BDNF decreased in the rTMS group but it increased in the sham group (P<0.05). Two months after treatment, RMBT scores in the rTMS group were higher than in the sham group, but not MoCA and LOTCA scores. Conclusions Low-frequency rTMS may improve after-stoke memory through various pathways, which may involve polymorphisms and several neural genes, but not through an increase in BDNF levels. PMID:25770310

Lu, Haitao; Zhang, Tong; Wen, Mei; Sun, Li

2015-01-01

247

Motor Threshold in Transcranial Magnetic Stimulation: The Impact of White Matter Fiber Orientation and Skull-to-Cortex Distance  

PubMed Central

The electrophysiology of transcranial magnetic stimulation (TMS) of motor cortex is not well understood. In this study, we investigate several structural parameters of the corticospinal tract and their relation to the TMS motor threshold (MT) in 17 subjects, with and without schizophrenia. We obtained structural and diffusion tensor MRI scans and measured the fractional anisotropy and principal diffusion direction for regions of interest in the corticospinal tract. We also measured the skull-to-cortex distance over the left motor region. The anterior–posterior trajectory of principle diffusion direction of the corticospinal tract and skull-to-cortex distance were both found to be highly correlated with MT, while fractional anisotropy, age and schizophrenia status were not. Two parameters—skull-to-cortex distance and the anterior component of the principle diffusion direction of the corticospinal tract as it passes the internal capsule—are highly predictive of MT in a linear regression model, and account for 82% of the variance observed (R2 = 0.82, F = 20.27, P < 0.0001) in measurements of MT. The corticospinal tract’s anterior–posterior direction alone contributes 13% of the variance explained. PMID:18973261

Herbsman, Tal; Forster, Lauren; Molnar, Christine; Dougherty, Robert; Christie, Doug; Koola, Jejo; Ramsey, Dave; Morgan, Paul S.; Bohning, Daryl E.; George, Mark S.; Nahas, Ziad

2010-01-01

248

Cerebellar-related long latency motor response in upper limb musculature by transcranial magnetic stimulation of the cerebellum.  

PubMed

In this study, we aimed to identify the cerebellum-related electromyographic (EMG) response that appeared in the upper limbs musculature. Thirty times averaged transcranial magnetic stimulation (TMS) with a double-cone coil placed over the cerebellar hemisphere elicited long latency EMG responses at the bilateral extensor carpi radialis (ECR) muscles. The peak latency of this EMG response was 70.7±12.7 ms in the ipsilateral ECR and 62.9±10.2 ms in the contralateral ECR of the TMS side. These latencies were much longer than the latency of the muscle evoked potential when we stimulated pyramidal tracts at the foramen magnum level. Cerebellar hemisphere loading by the finger target pursuit test made this EMG response faster during TMS on the ipsilateral side of the cerebellum and slower during TMS on the contralateral side of the cerebellum. Furthermore, the deeper the level of drowsiness, the slower the peak latency of this EMG response became. These results suggest that this EMG potential is a specific response of the cerebellum and brainstem reticular formation, and may be conducted from the cerebellar structure to the ECR muscle through the polysynaptic transmission of the reticulospinal tract. PMID:24113113

Hosokawa, Sachiyo; Hirata, Masayuki; Goto, Tetsu; Yanagisawa, Takufumi; Sugata, Hisato; Araki, Toshihiko; Okamura, Yumiko; Hasegawa, Yuka; Shinshi, Misako; Yorifuji, Shiro

2014-04-16

249

Improvement of white matter and functional connectivity abnormalities by repetitive transcranial magnetic stimulation in crossed aphasia in dextral  

PubMed Central

As a special aphasia, the occurrence of crossed aphasia in dextral (CAD) is unusual. This study aims to improve the language ability by applying 1 Hz repetitive transcranial magnetic stimulation (rTMS). We studied multiple modality imaging of structural connectivity (diffusion tensor imaging), functional connectivity (resting fMRI), PET, and neurolinguistic analysis on a patient with CAD. Furthermore, we applied rTMS of 1 Hz for 40 times and observed the language function improvement. The results indicated that a significantly reduced structural and function connectivity was found in DTI and fMRI data compared with the control. The PET imaging showed hypo-metabolism in right hemisphere and left cerebellum. In conclusion, one of the mechanisms of CAD is that right hemisphere is the language dominance. Stimulating left Wernicke area could improve auditory comprehension, stimulating left Broca’s area could enhance expression, and the results outlasted 6 months by 1 Hz rTMS balancing the excitability inter-hemisphere in CAD. PMID:25419415

Lu, Haitao; Wu, Haiyan; Cheng, Hewei; Wei, Dongjie; Wang, Xiaoyan; Fan, Yong; Zhang, Hao; Zhang, Tong

2014-01-01

250

An Investigation of the Late Excitatory Potentials in the Hand following Transcranial Magnetic Stimulation in Early Alzheimer's Disease  

PubMed Central

Background Recent neuroimaging studies in humans support the clinical observations that the motor cortex is affected early in the course of Alzheimer's disease (AD). Patients and Methods We measured the silent period (SP) induced by transcranial magnetic stimulation in AD patients in the very early stage of the disease, and we explored whether and in which way the pharmacologic manipulation of the cholinergic system could modify it. Results An increase in the duration of the SP was observed in AD patients in the early stage in comparison to controls. After 2 months of treatment with donepezil, the duration did not differ significantly from that of normal subjects. The results of our study show a fragmentation and an enlargement of the SP in the presence of multiple late excitatory potentials (LEPs) in early untreated AD patients. These LEPs were also modulated by donepezil. Conclusions The results suggest an early functional impairment of cholinergic neurotransmission in AD. The disturbance in acetylcholine output in early AD leads to a decrease in excitability of the motor system.

Balla, Christina; Maertens de Noordhout, Alain; Pepin, Jean Louis

2014-01-01

251

Magnetic resonance imaging/angiography and transcranial Doppler velocities in sickle cell anemia: results from the SWiTCH trial.  

PubMed

The Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) trial compared standard (transfusions/chelation) to alternative (hydroxyurea/phlebotomy) treatment to prevent recurrent stroke and manage iron overload in children chronically transfused over 7 years before enrollment. Standardized brain magnetic resonance imaging/magnetic resonance angiography (MRA) and transcranial Doppler (TCD) exams were performed at entry and exit, with a central blinded review. A novel MRA vasculopathy grading scale demonstrated frequent severe baseline left/right vessel stenosis (53%/41% ?Grade 4); 31% had no vessel stenosis on either side. Baseline parenchymal injury was prevalent (85%/79% subcortical, 53%/37% cortical, 50%/35% subcortical and cortical). Most children had low or uninterpretable baseline middle cerebral artery TCD velocities, which were associated with worse stenoses (incidence risk ratio [IRR] = 5.1, P ? .0001 and IRR = 4.1, P < .0001) than normal velocities; only 2% to 12% had any conditional/abnormal velocity. Patients with adjudicated stroke (7) and transient ischemic attacks (19 in 11 standard/8 alternative arm subjects) had substantial parenchymal injury/vessel stenosis. At exit, 1 child (alternative arm) had a new silent infarct, and another had worse stenosis. SWiTCH neuroimaging data document severe parenchymal and vascular abnormalities in children with SCA and stroke and support concerns about chronic transfusions lacking effectiveness for preventing progressive cerebrovascular injury. The novel SWiTCH vasculopathy grading scale warrants validation testing and consideration for use in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00122980. PMID:24914136

Helton, Kathleen J; Adams, Robert J; Kesler, Karen L; Lockhart, Alex; Aygun, Banu; Driscoll, Catherine; Heeney, Matthew M; Jackson, Sherron M; Krishnamurti, Lakshmanan; Miller, Scott T; Sarnaik, Sharada A; Schultz, William H; Ware, Russell E

2014-08-01

252

Safety, ethical considerations, and application guidelines for the use of transcranial magnetic stimulation in clinical practice and research?  

PubMed Central

This article is based on a consensus conference, which took place in Certosa di Pontignano, Siena (Italy) on March 7–9, 2008, intended to update the previous safety guidelines for the application of transcranial magnetic stimulation (TMS) in research and clinical settings. Over the past decade the scientific and medical community has had the opportunity to evaluate the safety record of research studies and clinical applications of TMS and repetitive TMS (rTMS). In these years the number of applications of conventional TMS has grown impressively, new paradigms of stimulation have been developed (e.g., patterned repetitive TMS) and technical advances have led to new device designs and to the real-time integration of TMS with electroencephalography (EEG), positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Thousands of healthy subjects and patients with various neurological and psychiatric diseases have undergone TMS allowing a better assessment of relative risks. The occurrence of seizures (i.e., the most serious TMS-related acute adverse effect) has been extremely rare, with most of the few new cases receiving rTMS exceeding previous guidelines, often in patients under treatment with drugs which potentially lower the seizure threshold. The present updated guidelines review issues of risk and safety of conventional TMS protocols, address the undesired effects and risks of emerging TMS interventions, the applications of TMS in patients with implanted electrodes in the central nervous system, and safety aspects of TMS in neuroimaging environments. We cover recommended limits of stimulation parameters and other important precautions, monitoring of subjects, expertise of the rTMS team, and ethical issues. While all the recommendations here are expert based, they utilize published data to the extent possible. PMID:19833552

Rossi, Simone; Hallett, Mark; Rossini, Paolo M.; Pascual-Leone, Alvaro

2011-01-01

253

Short-term effects of repetitive transcranial magnetic stimulation on speech and voice in individuals with Parkinson's disease.  

PubMed

The main characteristics of dysarthria in Parkinson's disease (PD) are monotony of pitch and loudness, reduced stress, variable speech rate, imprecise consonants, and breathy and harsh voice. Earlier treatment studies have shown that dysarthria is less responsive to both pharmacological and surgical treatments than other gross motor symptoms. Recent findings have suggested that repetitive transcranial magnetic stimulation (rTMS) may have a beneficial effect on vocal function in PD. In the present study, 10 individuals with mild PD and no or minimal dysarthria were treated with rTMS as well as placebo stimulation in a blinded experiment. Stimulation was delivered using a frequency of 10 Hz and a stimulation intensity of 90% of the motor threshold. The site of stimulation was the cortical area corresponding to the hand, on the hemisphere contralateral to the patient's most affected side. The participants were audio-recorded before and after both rTMS and sham stimulation. Acoustic analysis was performed on 3 sustained /a:/ for each of the 4 conditions, and analyzed both for the whole group as well as for men and women separately. Results showed that there were no significant differences between any of the conditions regarding duration of sustained fricative or sustained vowel phonation, diadochokinetic rates or intelligibility. Above all, the results of acoustic analyses showed an effect of placebo; there was a significant reduction in fundamental frequency (F(0)) variation, pitch period perturbation, amplitude period perturbation, noise-to-harmonics ratio and coefficient of variation in F(0) between the recordings performed before compared to after sham stimulation. PMID:20424465

Hartelius, L; Svantesson, P; Hedlund, A; Holmberg, B; Revesz, D; Thorlin, T

2010-01-01

254

Safety and tolerability of repetitive transcranial magnetic stimulation in patients with pathologic positive sensory phenomena: a review of literature  

PubMed Central

BACKGROUND Repetitive transcranial magnetic stimulation (rTMS) is emerging as a valuable therapeutic and diagnostic tool. rTMS appears particularly promising for disorders characterized by positive sensory phenomena attributable to alterations in sensory cortex excitability. Among these are tinnitus, auditory and visual hallucinations, and pain syndromes. OBJECTIVE Despite studies addressing rTMS efficacy in suppression of positive sensory symptoms, the safety of stimulation of potentially hyperexcitable cortex has not been fully addressed. We performed a systematic literature review and metanalysis to describe the rTMS safety profile in these disorders. METHODS Using the PubMed database, we performed an English-language literature search from January 1985 to April 2011 to review all pertinent publications. Per study, we noted and listed pertinent details. From these data we also calculated a crude per-subject risk for each adverse event. RESULTS 106 publications (n = 1815 subjects) were identified with patients undergoing rTMS for pathologic positive sensory phenomena. Adverse events associated with rTMS were generally mild and occurred in 16.7% of subjects. Seizure was the most serious adverse event, and occurred in three patients with a 0.16% crude per-subject risk. The second most severe adverse event involved aggravation of sensory phenomena, occurring in 1.54%. CONCLUSIONS The published data suggest rTMS for the treatment or diagnosis of pathologic positive sensory phenomena appears to be a relatively safe and well-tolerated procedure. However, published data are lacking in systematic reporting of adverse events, and safety risks of rTMS in these patient populations will have to be addressed in future prospective trials. PMID:22322098

Muller, Paul A; Pascual-Leone, Alvaro; Rotenberg, Alexander

2013-01-01

255

Anti-depressive mechanism of repetitive transcranial magnetic stimulation in rat: the role of the endocannabinoid system.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) to treat depression has been thoroughly investigated in recent years. However, the underlying mechanisms are not fully understood. In this study, a chronic unpredictable mild stress (CUMS) paradigm was applied to male Sprague Dawley rats. Then rTMS was performed for 7 consecutive days, and the anti-depressive effects were evaluated by the sucrose preference test (SPT), the forced swimming test (FST), and the open-field test (OFT). Hippocampal cannabinoid type I receptor (CB1) expression was measured, and the expression levels of brain-derived neurotrophic factor (BDNF), Bcl-2, and Bax and the number of bromodeoxyuridine (BrdU)-positive cells were also investigated. These parameters were also observed after the selective CB1 receptor antagonist AM251 was used as a blocking agent. The results showed that CUMS induced a significant decrease in sucrose preference, a significant increase in immobility time in the FST, and a significantly decreased horizontal distance in the OFT. In addition, reduced hippocampal CB1 receptor, BDNF, and Bcl-2/Bax protein expression levels in CUMS rats, as well as decreased cell proliferation were also observed in the dentate gyrus. Meanwhile, rTMS treatment up-regulated cell proliferation; elevated CB1 receptor, BDNF, and Bcl-2/Bax expression levels in the hippocampus; and ameliorated depressive-like behaviors. All of these beneficial effects were abolished by AM251. These results indicate that rTMS increases BDNF production and hippocampal cell proliferation to protect against CUMS-induced changes through its effect on CB1 receptors. PMID:24479995

Wang, Hua-ning; Wang, Lei; Zhang, Rui-guo; Chen, Yun-chun; Liu, Ling; Gao, Fang; Nie, Huang; Hou, Wu-gang; Peng, Zheng-wu; Tan, Qingrong

2014-04-01

256

The molecular evidence of neural plasticity induced by cerebellar repetitive transcranial magnetic stimulation in the rat brain: a preliminary report.  

PubMed

Cerebellar repetitive transcranial magnetic stimulation (rTMS) has been applied to treat several pathological conditions with insufficient evidence of molecular mechanism. Neural plasticity is proposed as one of mechanism. This study aimed to (1) confirm the feasibility of focal stimulation over cerebellar cortex and (2) investigate cerebellar rTMS effects on molecular changes associated with neural plasticity in the rat. For feasibility, six male Sprague-Dawley rats underwent (18)F-FDG positron emission tomography (PET) to confirm focal stimulation on the cerebellar cortex after rTMS. For molecular evidence, thirty rats underwent a single (N=15) or 10 sessions (N=15) of rTMS with low-, high-frequency, or sham stimulation. In cerebellar cortex, reverse-transcriptase polymerase chain reaction and western blotting were performed on mRNA and proteins associated with neural plasticity: metabotrophic glutamate receptor 1 (GluR1), 2-amino-5-methyl-4-isoxazole-propionatic acid (AMPA) receptor (GluR2) and protein kinase C (PKC). As a result, (18)F-FDG-PET showed an increase of glucose metabolism in the cerebellar cortex. The transcription of mGluR1 decreased following a single session of high-frequency rTMS. Synthesis of mGluR, PKC and GluR2 was reduced after rTMS, especially high frequency stimulation. It is suggested that rTMS could focus on the cerebellar cortex in the rat and induce neural plasticity associated with long-term depression. PMID:24861505

Lee, Seung Ah; Oh, Byung-Mo; Kim, Sang Jeong; Paik, Nam-Jong

2014-07-11

257

Low-intensity repetitive transcranial magnetic stimulation improves abnormal visual cortical circuit topography and upregulates BDNF in mice.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a treatment for neurological and psychiatric disorders. Although the induced field is focused on a target region during rTMS, adjacent areas also receive stimulation at a lower intensity and the contribution of this perifocal stimulation to network-wide effects is poorly defined. Here, we examined low-intensity rTMS (LI-rTMS)-induced changes on a model neural network using the visual systems of normal (C57Bl/6J wild-type, n = 22) and ephrin-A2A5(-/-) (n = 22) mice, the latter possessing visuotopic anomalies. Mice were treated with LI-rTMS or sham (handling control) daily for 14 d, then fluorojade and fluororuby were injected into visual cortex. The distribution of dorsal LGN (dLGN) neurons and corticotectal terminal zones (TZs) was mapped and disorder defined by comparing their actual location with that predicted by injection sites. In the afferent geniculocortical projection, LI-rTMS decreased the abnormally high dispersion of retrogradely labeled neurons in the dLGN of ephrin-A2A5(-/-) mice, indicating geniculocortical map refinement. In the corticotectal efferents, LI-rTMS improved topography of the most abnormal TZs in ephrin-A2A5(-/-) mice without altering topographically normal TZs. To investigate a possible molecular mechanism for LI-rTMS-induced structural plasticity, we measured brain derived neurotrophic factor (BDNF) in the visual cortex and superior colliculus after single and multiple stimulations. BDNF was upregulated after a single stimulation for all groups, but only sustained in the superior colliculus of ephrin-A2A5(-/-) mice. Our results show that LI-rTMS upregulates BDNF, promoting a plastic environment conducive to beneficial reorganization of abnormal cortical circuits, information that has important implications for clinical rTMS. PMID:25100609

Makowiecki, Kalina; Harvey, Alan R; Sherrard, Rachel M; Rodger, Jennifer

2014-08-01

258

Effect of chronic and acute low-frequency repetitive transcranial magnetic stimulation on spatial memory in rats.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is a novel, non-invasive neurological and psychiatric tool. The low-frequency (1 Hz or less) rTMS is likely to play a particular role in its mechanism of action with different effects in comparison with high-frequency (>1 Hz) rTMS. There is limited information regarding the effect of low-frequency rTMS on spatial memory. In our study, each male Wistar rat was daily given 300 stimuli (1.0 T, 200 micros) at a rate of 0.5 Hz or sham stimulation. We investigated the effects of chronic and acute rTMS on reference/working memory process in Morris water maze test with the hypothesis that the effect would differ by chronic or acute condition. Chronic low-frequency rTMS impaired the retrieval of spatial short- and long-term spatial reference memory but not acquisition process and working memory, whereas acute low-frequency rTMS predominantly induced no deficits in acquisition or short-term spatial reference memory as well as working memory except for long-term reference memory. In summary, chronic 0.5 Hz rTMS disrupts spatial short- and long-term reference memory function, but acute rTMS differently affects reference memory. Chronic low-frequency rTMS may be used to modulate reference memory. Treatment protocols using low-frequency rTMS in neurological and psychiatric disorders need to take into account the potential effect of chronic low-frequency rTMS on memory and other cognitive functions. PMID:17259018

Li, Wei; Yang, Yuye; Ye, Qing; Yang, Bo; Wang, Zhengrong

2007-03-15

259

Diffusion tensor fiber tracking in patients with central post-stroke pain; correlation with efficacy of repetitive transcranial magnetic stimulation.  

PubMed

Central post-stroke pain (CPSP) is one of the most common types of intractable pain. We reported that repetitive transcranial magnetic stimulation (rTMS) of primary motor cortex relieves pain for patients who were refractory to medical treatment. But the mechanism is unclear. In the present study, we investigated relations between the characteristics of CPSP and the results of fiber tracking, which is the only noninvasive method of evaluating the anatomical connectivity of white matter pathways. Fiber tracking of the corticospinal tract (CST) and thalamocortical tract (TCT) was investigated in 17 patients with CPSP. The stroke lesion was located in a supratentorial region in all cases (corona radiata, one case; thalamus, seven cases; putamen, nine cases). Relations between the delineation ratio (defined as the ratio of the cross section of the affected side to that of the unaffected side) of the CST and of the TCT, manual muscle test score, pain score, region of pain, and efficacy of rTMS were evaluated. Fiber tracking was successful in 13 patients with the stroke lesion involving the TCT. The rTMS-effective group had higher delineation ratio of the CST (p=0.02) and the TCT (p=0.005) than the rTMS-ineffective group. Previous studies suggested that an intact CST allows pain control but did not discuss the TCT. Our results suggest that the TCT also plays a role in pain reduction by rTMS of the primary motor cortex and that the efficacy of rTMS for patients with CPSP is predictable by fiber tracking. PMID:19004554

Goto, Tetsu; Saitoh, Youichi; Hashimoto, Naoya; Hirata, Masayuki; Kishima, Haruhiko; Oshino, Satoru; Tani, Naoki; Hosomi, Koichi; Kakigi, Ryusuke; Yoshimine, Toshiki

2008-12-01

260

Low-Intensity Repetitive Transcranial Magnetic Stimulation Improves Abnormal Visual Cortical Circuit Topography and Upregulates BDNF in Mice  

PubMed Central

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a treatment for neurological and psychiatric disorders. Although the induced field is focused on a target region during rTMS, adjacent areas also receive stimulation at a lower intensity and the contribution of this perifocal stimulation to network-wide effects is poorly defined. Here, we examined low-intensity rTMS (LI-rTMS)-induced changes on a model neural network using the visual systems of normal (C57Bl/6J wild-type, n = 22) and ephrin-A2A5?/? (n = 22) mice, the latter possessing visuotopic anomalies. Mice were treated with LI-rTMS or sham (handling control) daily for 14 d, then fluorojade and fluororuby were injected into visual cortex. The distribution of dorsal LGN (dLGN) neurons and corticotectal terminal zones (TZs) was mapped and disorder defined by comparing their actual location with that predicted by injection sites. In the afferent geniculocortical projection, LI-rTMS decreased the abnormally high dispersion of retrogradely labeled neurons in the dLGN of ephrin-A2A5?/? mice, indicating geniculocortical map refinement. In the corticotectal efferents, LI-rTMS improved topography of the most abnormal TZs in ephrin-A2A5?/? mice without altering topographically normal TZs. To investigate a possible molecular mechanism for LI-rTMS-induced structural plasticity, we measured brain derived neurotrophic factor (BDNF) in the visual cortex and superior colliculus after single and multiple stimulations. BDNF was upregulated after a single stimulation for all groups, but only sustained in the superior colliculus of ephrin-A2A5?/? mice. Our results show that LI-rTMS upregulates BDNF, promoting a plastic environment conducive to beneficial reorganization of abnormal cortical circuits, information that has important implications for clinical rTMS. PMID:25100609

Makowiecki, Kalina; Harvey, Alan R.; Sherrard, Rachel M.

2014-01-01

261

Transcranial magnetic stimulation: potential treatment for co-occurring alcohol, traumatic brain injury and posttraumatic stress disorders  

PubMed Central

Alcohol use disorder (AUD), mild traumatic brain injury (mTBI), and posttraumatic stress disorder (PTSD) commonly co-occur (AUD + mTBI + PTSD). These conditions have overlapping symptoms which are, in part, reflective of overlapping neuropathology. These conditions become problematic because their co-occurrence can exacerbate symptoms. Therefore, treatments must be developed that are inclusive to all three conditions. Repetitive transcranial magnetic stimulation (rTMS) is non-invasive and may be an ideal treatment for co-occurring AUD + mTBI + PTSD. There is accumulating evidence on rTMS as a treatment for people with AUD, mTBI, and PTSD each alone. However, there are no published studies to date on rTMS as a treatment for co-occurring AUD + mTBI + PTSD. This review article advances the knowledge base for rTMS as a treatment for AUD + mTBI + PTSD. This review provides background information about these co-occurring conditions as well as rTMS. The existing literature on rTMS as a treatment for people with AUD, TBI, and PTSD each alone is reviewed. Finally, neurobiological findings in support of a theoretical model are discussed to inform TMS as a treatment for co-occurring AUD + mTBI + PTSD. The peer-reviewed literature was identified by targeted literature searches using PubMed and supplemented by cross-referencing the bibliographies of relevant review articles. The existing evidence on rTMS as a treatment for these conditions in isolation, coupled with the overlapping neuropathology and symptomology of these conditions, suggests that rTMS may be well suited for the treatment of these conditions together. PMID:25422632

Herrold, Amy A.; Kletzel, Sandra L.; Harton, Brett C.; Chambers, R. Andrew; Jordan, Neil; Pape, Theresa Louise-Bender

2014-01-01

262

Changes in motor cortex excitability associated with temporal repetitive transcranial magnetic stimulation in tinnitus: hints for cross-modal plasticity?  

PubMed Central

Background Motor cortex excitability was found to be changed after repetitive transcranial magnetic stimulation (rTMS) of the temporal cortex highlighting the occurrence of cross-modal plasticity in non-invasive brain stimulation. Here, we investigated the effects of temporal low-frequency rTMS on motor cortex plasticity in a large sample of tinnitus patients. In 116 patients with chronic tinnitus different parameters of cortical excitability were assessed before and after ten rTMS treatment sessions. Patients received one of three different protocols all including 1 Hz rTMS over the left temporal cortex. Treatment response was defined as improvement by at least five points in the tinnitus questionnaire (TQ). Variables of interest were resting motor threshold (RMT), short-interval intra-cortical inhibition (SICI), intracortical facilitation (ICF), and cortical silent period (CSP). Results After rTMS treatment RMT was decreased by about 1% of stimulator output near-significantly in the whole group of patients. SICI was associated with significant changes with respect to treatment response. The group of treatment responders showed a decrease of SICI over the course of treatment, the group of non-responders the reverse pattern. Conclusions Minor RMT changes during rTMS treatment do not necessarily suggest the need for systematic re-examination of the RMT for safety and efficacy issues. Treatment response to rTMS was shown to be related to changes in SICI that might reflect modulation of GABAergic mechanisms directly or indirectly related to rTMS treatment effects. PMID:24898574

2014-01-01

263

Medium-term results of combined treatment with transcranial magnetic stimulation and antidepressant drug for chronic tinnitus.  

PubMed

We compared the effects of repetitive transcranial magnetic stimulation (rTMS) and paroxetine [a selective serotonin reuptake inhibitor (SSRI)] on tinnitus in terms of effectiveness and medium-term results. This is a randomised, double-blind, placebo-controlled study. Seventy-five patients with moderate tinnitus were divided into five equal groups. Each group was treated for 1 month as follows: group 1 received rTMS alone at 1 Hz frequency; group 2 received rTMS alone at 10 Hz frequency; group 3 received rTMS at 1 Hz frequency combined with paroxetine; group 4 received paroxetine alone; and group 5 received a placebo (sham rTMS). Participants were tested using the Tinnitus Handicap Inventory (THI), Tinnitus Severity Index (TSI), the Beck Anxiety Scoring (BAS), and Psychiatric Sign Screening (PSS) tests. THI, TSI, BAS, and PSS were measured prior to treatment, and at the first and sixth month post-treatment. The THI and TSI scores improved after treatment in all groups, except the placebo group. The THI scores in groups 1 and 2 showed a statistically significant improvement after the first and sixth month compared to pretreatment scores, whereas a significant improvement in THI scores occurred only after the sixth month in groups 3 and 4. The TSI scores in group 3 showed a significant improvement at the first and sixth month marks after treatment. The rTMS and SSRI play potential roles in the reduction of tinnitus severity, but without cumulative or synergistic effects when a combination of treatment regimens is applied. These positive effects might be due to the relationship between the auditory cortex areas related to emotions and tinnitus. PMID:24337899

Bilici, Suat; Yigit, Ozgur; Taskin, Umit; Gor, Ayse Pelin; Yilmaz, Enver Demirel

2015-02-01

264

Carbonic Anhydrase I, II, and VI, Blood Plasma, Erythrocyte and Saliva Zinc and Copper Increase After Repetitive Transcranial Magnetic Stimulation  

PubMed Central

Introduction Repetitive transcranial magnetic stimulation (rTMS) has been used to treat symptoms from many disorders; biochemical changes occurred with this treatment. Preliminary studies with rTMS in patients with taste and smell dysfunction improved sensory function and increased salivary carbonic anhydrase (CA) VI and erythrocyte CA I, II. To obtain more information about these changes after rTMS, we measured changes in several CA enzymes, proteins, and trace metals in their blood plasma, erythrocytes, and saliva. Methods Ninety-three patients with taste and smell dysfunction were studied before and after rTMS in an open clinical trial. Before and after rTMS, we measured erythrocyte CA I, II and salivary CA VI, zinc and copper in parotid saliva, blood plasma, and erythrocytes, and appearance of novel salivary proteins by using mass spectrometry. Results After rTMS, CA I, II and CA VI activity and zinc and copper in saliva, plasma, and erythrocytes increased with significant sensory benefit. Novel salivary proteins were induced at an m/z value of 21.5K with a repetitive pattern at intervals of 5K m/z. Conclusions rTMS induced biochemical changes in specific enzymatic activities, trace metal concentrations, and induction of novel salivary proteins, with sensory improvement in patients with taste and smell dysfunction. Because patients with several neurologic disorders exhibit taste and smell dysfunction, including Parkinson disease, Alzheimer disease, and multiple sclerosis, and because rTMS improved their clinical symptoms, the biochemical changes we observed may be relevant not only in our patients with taste and smell dysfunction but also in patients with neurologic disorders with these sensory abnormalities. PMID:20090508

Henkin, Robert I.; Potolicchio, Samuel J.; Levy, Lucien M.; Moharram, Ramy; Velicu, Irina; Martin, Brian M.

2010-01-01

265

Synergistic effects of noradrenergic modulation with atomoxetine and 10 Hz repetitive transcranial magnetic stimulation on motor learning in healthy humans  

PubMed Central

Background Repetitive transcranial magnetic stimulation (rTMS) is able to induce changes in neuronal activity that outlast stimulation. The underlying mechanisms are not completely understood. They might be analogous to long-term potentiation or depression, as the duration of the effects seems to implicate changes in synaptic plasticity. Norepinephrine (NE) has been shown to play a crucial role in neuronal plasticity in the healthy and injured human brain. Atomoxetine (ATX) and other NE reuptake inhibitors have been shown to increase excitability in different systems and to influence learning processes. Thus, the combination of two facilitative interventions may lead to further increase in excitability and motor learning. But in some cases homeostatic metaplasticity might protect the brain from harmful hyperexcitability. In this study, the combination of 60 mg ATX and 10 Hz rTMS over the primary motor cortex was used to examine changes in cortical excitability and motor learning and to investigate their influence on synaptic plasticity mechanisms. Results The results of this double-blind placebo-controlled study showed that ATX facilitated corticospinal and intracortical excitability in motor cortex. 10 Hertz rTMS applied during a motor task was able to further increase intracortical excitability only in combination with ATX. In addition, only the combination of 10 Hz rTMS and ATX was capable of enhancing the total number of correct responses and reaction time significantly, indicating an interaction effect between rTMS and ATX without signs of homeostatic metaplasticity. Conclusion These results suggest that pharmacologically enhanced NE transmission and 10 Hz rTMS exert a synergistic effect on motor cortex excitability and motor learning in healthy humans. PMID:24690416

2014-01-01

266

Transcranial direct current stimulation (tDCS) produces localized and specific alterations in neurochemistry: a ¹H magnetic resonance spectroscopy study.  

PubMed

Transcranial direct current stimulation (tDCS) has been found to produce significant changes in behavior, including a large increase of learning and performance for a difficult visual perceptual task (Clark et al., NeuroImage 2010). The mechanisms by which tDCS produces these behavioral effects are currently uncertain. One hypothesis is that anodal tDCS leads to increased metabolic activity in the brain, which enhances cognitive and memory processes. Here we examined the neuronal mechanisms by which tDCS influences learning by measuring changes in brain metabolite concentrations using proton magnetic resonance spectroscopy (¹H MRS). As perception and learning can also influence neurochemistry, here we applied tDCS during rest. MRS data was obtained before and after 2.0 mA of anodal tDCS was applied for 30 min over electrode site P4, with the cathode placed on the contralateral arm. MRS data were acquired from the right parietal lobe beneath the anodal tDCS electrode, and from the homologous regions of the left hemisphere once before and once after tDCS. Significantly higher combined glutamate and glutamine levels were found in right parietal cortex, beneath the stimulating electrode, with non-significant increases in homologous regions of the opposite hemisphere. In addition, a significant interaction between hemispheres was found for tDCS effects on tNAA. These results suggest that changes in glutamatergic activity and tNAA may be related to the mechanisms by which tDCS influences learning and behavior. PMID:21683766

Clark, Vincent P; Coffman, Brian A; Trumbo, Michael C; Gasparovic, Charles

2011-08-01

267

Corticospinal excitability in human subjects during nonrapid eye movement sleep: single and paired-pulse transcranial magnetic stimulation study.  

PubMed

The mechanisms responsible for changes in brain function during normal sleep are poorly understood. In this study, we aimed to investigate the effects of sleep on human corticospinal excitability by estimating resting motor threshold (RMT), and latency and amplitude of motor-evoked potentials (MEPs) after delivering transcranial magnetic stimulation (TMS) in ten healthy subjects. We also aimed to study short-interval intracortical inhibition (SICI) during sleep with paired-pulse TMS (pp-TMS). Ten healthy volunteers were studied. They were monitored immediately before, during and after a 3-h sleep (from 1 p.m. to 4 p.m., immediately after the mid-day meal). EEG was continuously recorded during sleep and the various sleep stages were identified off line. Every 10 min, subjects received ten single stimuli (to estimate RMT, MEP latency and amplitude) and six paired stimuli (to estimate SICI). MEP amplitude decreased and latency and RMT increased during the various sleep stages and returned to baseline values on awakening. Post hoc comparisons showed a significant difference in pp-TMS MEP amplitudes between the sleep and all the other conditions. The changes in TMS evoked variables during the different sleep stages indicate that during nonrapid eye movement sleep, cortical pyramidal neuron excitability (as measured by RMT, MEP latency and amplitude) progressively diminishes and the efficiency of the intracortical GABA-ergic network (as assessed by three pp-TMS) increases. On awakening, these sleep-induced changes in corticospinal excitability return rapidly to values observed during wakefulness. PMID:18231786

Avesani, Mirko; Formaggio, Emanuela; Fuggetta, Giorgio; Fiaschi, Antonio; Manganotti, Paolo

2008-05-01

268

Task-related changes in intracortical inhibition assessed with paired- and triple-pulse transcranial magnetic stimulation.  

PubMed

Recent research has demonstrated a task-related modulation of postsynaptic intracortical inhibition within primary motor cortex for tasks requiring isolated (abduction) or synergistic (precision grip) muscle activation. The current study sought to investigate task-related changes in pre- and postsynaptic intracortical inhibition in motor cortex. In 13 young adults (22.5 ± 3.5 yr), paired-pulse transcranial magnetic stimulation (TMS) was used to measure short (SICI)- and long-interval intracortical inhibition (LICI) (i.e., postsynaptic motor cortex inhibition) in first dorsal interosseous muscle, and triple-pulse TMS was used to investigate changes in SICI-LICI interactions (i.e., presynaptic motor cortex inhibition). These measurements were obtained at rest and during muscle activation involving isolated abduction of the index finger and during a precision grip using the index finger and thumb. SICI was reduced during abduction and precision grip compared with rest, with greater reductions during precision grip. The modulation of LICI during muscle activation depended on the interstimulus interval (ISI; 100 and 150 ms) but was not different between abduction and precision grip. For triple-pulse TMS, SICI was reduced in the presence of LICI at both ISIs in resting muscle (reflecting presynaptic motor cortex inhibition) but was only modulated at the 150-ms ISI during index finger abduction. Results suggest that synergistic contractions are accompanied by greater reductions in postsynaptic motor cortex inhibition than isolated contractions, but the contribution of presynaptic mechanisms to this disinhibition is limited. Furthermore, timing-dependent variations in LICI provide additional evidence that measurements using different ISIs may not represent activation of the same cortical process. PMID:25475354

Opie, George M; Ridding, Michael C; Semmler, John G

2015-03-01

269

Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

The present study analyzed the effects of monophasic magnetic stimulation to the motor cortex. The effects of magnetic stimulation were evaluated by analyzing the motor evoked potentials (MEPs). The amplitude and latency of MEPs on the abductor pollicis brevis muscle were used to evaluate the effects of repetitive magnetic stimulation. A figure eight-shaped flat coil was used to stimulate the region over the primary motor cortex. The intensity of magnetic stimulation was 120% of the resting motor threshold, and the frequency of magnetic stimulation was 0.1 Hz. In addition, the direction of the current in the brain was posterior-anterior (PA) or anterior-posterior (AP). The latency of MEP was compared with PA and AP on initial magnetic stimulation. The results demonstrated that a stimulus in the AP direction increased the latency of the MEP by approximately 2.5 ms. MEP amplitude was also compared with PA and AP during 60 magnetic stimulations. The results showed that a stimulus in the PA direction gradually increased the amplitude of the MEP. However, a stimulus in the AP direction did not modulate the MEP amplitude. The average MEP amplitude induced from every 10 magnetic pulses was normalized by the average amplitude of the first 10 stimuli. These results demonstrated that the normalized MEP amplitude increased up to approximately 150%. In terms of pyramidal neuron indirect waves (I waves), magnetic stimulation inducing current flowing backward to the anterior preferentially elicited an I1 wave, and current flowing forward to the posterior elicited an I3 wave. It has been reported that the latency of the I3 wave is approximately 2.5 ms longer than the I1 wave elicitation, so the resulting difference in latency may be caused by this phenomenon. It has also been reported that there is no alteration of MEP amplitude at a frequency of 0.1 Hz. However, this study suggested that the modulation of MEP amplitude depends on stimulation strength and stimulation direction.

Sato, Aya; Torii, Tetsuya; Iwahashi, Masakuni; Itoh, Yuji; Iramina, Keiji

2014-05-01

270

Topiramate modulates excitability of the occipital cortex when measured by transcranial magnetic stimulation  

Microsoft Academic Search

The aim of this study was to measure differences in occipital cortex excitability in migraineurs before and after administration of topiramate. We have previously demonstrated occipital cortex hyperexcitability in migraine using an objective technique of magnetic suppression of perceptual accuracy (MSPA). We hypothesized that a neuromodulator such as topiramate would demonstrate differences in MSPA in migraine compared with baseline. Ten

SK Aurora; PM Barrodale; AR Vermaas; CB Rudra

2010-01-01

271

Modulation of cortical excitability induced by repetitive transcranial magnetic stimulation: influence of timing and geometrical parameters and underlying mechanisms.  

PubMed

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique that activates neurons via generation of brief pulses of high-intensity magnetic field. If these pulses are applied in a repetitive fashion (rTMS), persistent modulation of neural excitability can be achieved. The technique has proved beneficial in the treatment of a number of neurological and psychiatric conditions. However, the effect of rTMS on excitability and the other performance indicators shows a considerable degree of variability across different sessions and subjects. The frequency of stimulation has always been considered as the main determinant of the direction of excitability modulation. However, interactions exist between frequency and several other stimulation parameters that also influence the degree of modulation. In addition, the spatial interaction of the transient electric field induced by the TMS pulse with the cortical neurons is another contributor to variability. Consideration of all of these factors is necessary in order to improve the consistency of the conditioning effect and to better understand the outcomes of investigations with rTMS. These user-controlled sources of variability are discussed against the background of the mechanisms that are believed to drive the excitability changes. The mechanism behind synaptic plasticity is commonly accepted as the driver of sustained excitability modulation for rTMS and indeed, plasticity and rTMS share many characteristics, but definitive evidence is lacking for this. It is more likely that there is a multiplicity of mechanisms behind the action of rTMS. The different mechanisms interact with each other and this will contribute to the variability of rTMS-induced excitability changes. This review investigates the links between rTMS and synaptic plasticity, describes their similarities and differences, and highlights a neglected contribution of the membrane potential. In summary, the principal aims of this review are (i) to discuss the different experimental and subject-related factors that contribute to the variability of excitability modulation induced by rTMS, and (ii) to discuss a generalized underlying mechanism for the excitability modulation. PMID:21056619

Pell, Gaby S; Roth, Yiftach; Zangen, Abraham

2011-01-01

272

Resting and active motor thresholds versus stimulus–response curves to determine transcranial magnetic stimulation intensity in quadriceps femoris  

PubMed Central

Background Transcranial magnetic stimulation (TMS) is a widely-used investigative technique in motor cortical evaluation. Recently, there has been a surge in TMS studies evaluating lower-limb fatigue. TMS intensity of 120-130% resting motor threshold (RMT) and 120% active motor threshold (AMT) and TMS intensity determined using stimulus–response curves during muscular contraction have been used in these studies. With the expansion of fatigue research in locomotion, the quadriceps femoris is increasingly of interest. It is important to select a stimulus intensity appropriate to evaluate the variables, including voluntary activation, being measured in this functionally important muscle group. This study assessed whether selected quadriceps TMS stimulus intensity determined by frequently employed methods is similar between methods and muscles. Methods Stimulus intensity in vastus lateralis, rectus femoris and vastus medialis muscles was determined by RMT, AMT (i.e. during brief voluntary contractions at 10% maximal voluntary force, MVC) and maximal motor-evoked potential (MEP) amplitude from stimulus–response curves during brief voluntary contractions at 10, 20 and 50% MVC at different stimulus intensities. Results Stimulus intensity determined from a 10% MVC stimulus–response curve and at 120 and 130% RMT was higher than stimulus intensity at 120% AMT (lowest) and from a 50% MVC stimulus–response curve (p??0.05). Conclusions Similar optimal stimulus intensity and maximal MEP amplitudes at 20 and 50% MVC and the minimal risk of residual fatigue at 20% MVC suggest that a 20% MVC stimulus–response curve is appropriate for determining TMS stimulus intensity in the quadriceps femoris. The higher selected stimulus intensities at 120-130% RMT have the potential to cause increased coactivation and discomfort and the lower stimulus intensity at 120% AMT may underestimate evoked responses. One muscle may also act as a surrogate in determining optimal quadriceps femoris stimulation intensity. PMID:24655366

2014-01-01

273

The long-term effects of sports concussion on retired Australian football players: a study using transcranial magnetic stimulation.  

PubMed

This study investigated corticomotor excitability and inhibition, cognitive functioning, and fine motor dexterity in retired elite and amateur Australian football (AF) players who had sustained concussions during their playing careers. Forty male AF players who played at the elite level (n=20; mean age 49.7±5.7 years) or amateur level (n=20; mean age 48.4±6.9 years), and had sustained on average 3.2 concussions 21.9 years previously, were compared with 20 healthy age-matched male controls (mean age 47.56±6.85 years). All participants completed assessments of fine dexterity, visuomotor reaction time, spatial working memory (SWM), and associative learning (AL). Transcranial magnetic stimulation (TMS) was used to measure corticospinal excitability: stimulus-response (SR) curves and motor evoked potential (MEP) 125% of active motor threshold (aMT); and intracortical inhibition: cortical silent period (cSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI). Healthy participants performed better in dexterity (p=0.003), reaction (p=0.003), and movement time (p=0.037) than did both AF groups. Differences between AF groups were found in AL (p=0.027) and SWM (p=0.024). TMS measures revealed that both AF groups showed reduced cSP duration at 125% aMT (p>0.001) and differences in SR curves (p>0.001) than did healthy controls. Similarly, SICI (p=0.012) and LICI (p=0.009) were reduced in both AF groups compared with controls. Regression analyses revealed a significant contribution to differences in motor outcomes with the three measures of intracortical inhibition. The measures of inhibition differed, however, in terms of which performance measure they had a significant and unique predictive relationship with, reflecting the variety of participant concussion injuries. This study is the first to demonstrate differences in motor control and intracortical inhibition in AF players who had sustained concussions during their playing career two decades previously. PMID:24579780

Pearce, Alan J; Hoy, Kate; Rogers, Mark A; Corp, Daniel T; Maller, Jerome J; Drury, Hannah G K; Fitzgerald, Paul B

2014-07-01

274

Deep-brain magnetic stimulation promotes adult hippocampal neurogenesis and alleviates stress-related behaviors in mouse models for neuropsychiatric disorders  

PubMed Central

Background Repetitive Transcranial Magnetic Stimulation (rTMS)/ Deep-brain Magnetic Stimulation (DMS) is an effective therapy for various neuropsychiatric disorders including major depression disorder. The molecular and cellular mechanisms underlying the impacts of rTMS/DMS on the brain are not yet fully understood. Results Here we studied the effects of deep-brain magnetic stimulation to brain on the molecular and cellular level. We examined the adult hippocampal neurogenesis and hippocampal synaptic plasticity of rodent under stress conditions with deep-brain magnetic stimulation treatment. We found that DMS promotes adult hippocampal neurogenesis significantly and facilitates the development of adult new-born neurons. Remarkably, DMS exerts anti-depression effects in the learned helplessness mouse model and rescues hippocampal long-term plasticity impaired by restraint stress in rats. Moreover, DMS alleviates the stress response in a mouse model for Rett syndrome and prolongs the life span of these animals dramatically. Conclusions Deep-brain magnetic stimulation greatly facilitates adult hippocampal neurogenesis and maturation, also alleviates depression and stress-related responses in animal models. PMID:24512669

2014-01-01

275

Functional Dopaminergic Neurons in Substantia Nigra are Required for Transcranial Magnetic Stimulation-Induced Motor Plasticity.  

PubMed

Repetitive magnetic stimulation (rTMS), including theta burst stimulation (TBS), is capable of modulating motor cortical excitability through plasticity-like mechanisms and might have therapeutic potential for Parkinson's disease (PD). An animal model would be helpful for elucidating the mechanism of rTMS that remain unclear and controversial. Here, we have established a TMS model in rat and applied this model to study the impact of substantia nigra dopamine neuron on TBS-induced motor plasticity in PD rats. In parallel with human results, continuous TBS (cTBS) successfully suppressed motor evoked potentials (MEPs), while MEPs increased after intermittent TBS (iTBS) in healthy rats. We then tested the effect of iTBS in early and advanced 6-hydroxydopamine (6-OHDA)-lesioned PD. Moreover, dopaminergic neurons in substantia nigra and rotation behavior were assessed to correlate with the amount of iTBS-induced plasticity. In results, iTBS-induced potentiation was reduced in early PD rats and was absent in advanced PD rats. Such reduction in plasticity strongly correlated with the dopaminergic cell loss and the count of rotation in PD rats. In conclusion, we have established a TMS PD rat model. With the help of this model, we confirmed the loss of domaninergic neurons in substantia nigra resulting in reduced rTMS-induced motor plasticity in PD. PMID:24451657

Hsieh, Tsung-Hsun; Huang, Ying-Zu; Rotenberg, Alexander; Pascual-Leone, Alvaro; Chiang, Yung-Hsiao; Wang, Jia-Yi; Chen, Jia-Jin J

2014-01-22

276

Musical training-induced functional reorganization of the adult brain: functional magnetic resonance imaging and transcranial magnetic stimulation study on amateur string players.  

PubMed

We used the combined technique of functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to observe changes that occur in adult brains after the practice of stringed musical instruments. We carried out fMRI on eight volunteers (aged 20-22 years): five novices and three individuals who had discontinued practice for more than 5 years. The motor paradigm contained a repetitive lift-abduction/fall-adduction movement of the left/right little finger, carried out with maximum efforts without pacing. The sensory paradigm was to stimulate the same little finger using a string. In parallel to the fMRI acquisition, TMS motor maps for the little finger were obtained using a frameless stereotactic neuronavigation system. After the baseline study, each participant began to learn a stringed instrument. Newly developed fMRI activations for the left little finger were observed 6 months after practice at multiple brain regions including inferior parietal lobule, premotor area (PMA), left precuneus, right anterior superior temporal gyrus, and posterior middle temporal gyrus. In contrast, new activations were rarely observed for the right little finger. The TMS study revealed new motor representation sites for the left little finger in the PMA or supplementary motor area (SMA). Unexpectedly, TMS motor maps for the right little finger were reduced significantly. Among new fMRI activations for sensory stimuli of the left little finger, the cluster of highest activation was located in the SMA. Collectively, these data provide insight into orchestrated reorganization of the sensorimotor and temporal association cortices contributing to the skillful fingering and musical processing after the practice of playing stringed instruments. PMID:15449354

Kim, Dong-Eog; Shin, Min-Jung; Lee, Kyoung-Min; Chu, Kon; Woo, Sung Ho; Kim, Young Ro; Song, Eun-Cheol; Lee, Jun-Won; Park, Seong-Ho; Roh, Jae-Kyu

2004-12-01

277

Electric vs magnetic trans-cranial stimulation of the brain in healthy humans: a comparative study of central motor tracts 'conductivity' and 'excitability'.  

PubMed

Motor evoked potentials (MEPs) were elicited in the thenar muscles of 11 healthy volunteers via individual electric unifocal and magnetic trans-cranial stimuli (TCS). The effects of TCS strength, of the muscular state (relaxed, contracted) as well as of the amplitude-latency characteristics and the duration of the motor tracts central conduction times (CCTs) to hand muscles, were evaluated and compared between the two types of brain excitation. MEPs with the shortest latency (18.91 +/- 1.31 ms) were recorded in the voluntarily contracted muscle during electric TCS, whilst those with maximal latency (23.3 +/- 1.63 ms) were found after magnetic TCS with an intensity at threshold for eliciting an MEP of about 0.1 mV in the relaxed muscle. Mean CCTs for electric and magnetic TCS calculated in the contracted target muscles, were respectively 5.07 +/- 0.51 and 6.34 +/- 0.46 ms. MEPs with larger amplitudes and durations were observed during magnetic TCS, being maximal when suprathreshold stimuli were delivered. A restricted range of liminar values of magnetic TCS was obtained by defining the threshold for raising motor responses in complete muscle relaxation, indicating that magnetic pulses might represent a useful probe for testing the 'excitability' of the motor tracts. PMID:2924156

Caramia, M D; Pardal, A M; Zarola, F; Rossini, P M

1989-02-01

278

Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory  

Microsoft Academic Search

Previous studies have claimed that weak transcranial direct current stimulation (tDCS) induces persisting excitability changes in the human motor cortex that can be more pronounced than cortical modulation induced by transcranial magnetic stimulation, but there are no studies that have evaluated the effects of tDCS on working memory. Our aim was to determine whether anodal transcranial direct current stimulation, which

Felipe Fregni; Paulo S. Boggio; Michael Nitsche; Felix Bermpohl; Andrea Antal; Eva Feredoes; Marco A. Marcolin; Sergio P. Rigonatti; Maria T. A. Silva; Walter Paulus; Alvaro Pascual-Leone

2005-01-01

279

3390 IEEE TRANSACTIONS ON MAGNETICS, VOL. 39, NO. 5, SEPTEMBER 2003 The Effect of Transcranial Magnetic Stimulation on  

E-print Network

cosine current pulses 238 in duration. The peak magnetic fields were set to 0.50 T ( motor threshold) and 1.25 T ( motor threshold) at the center of the coil. Rats received 10 1 s trains of 25 pulses of Medicine, University of Tokyo, Tokyo, Japan (e-mail: ogiue@medes.m.u-tokyo.ac.jp; ueno@medes.m.u-tokyo

Kawato, Suguru

280

Repetitive transcranial magnetic stimulation induced hypomanic symptoms in a woman with a history of electroconvulsive therapy induced mania:  a case report  

PubMed Central

Repetitive transcranial magnetic stimulation (rTMS) is a comparatively novel option for the treatment of major depressive disorder (MDD) and other psychiatric illnesses. Previous research has shown rTMS to be safe and without significant side effects compared to pharmacologic options. However, rare cases of rTMS-induced mania have been reported. This case report describes such an affective switch in a 52 year old female veteran with treatment-resistant MDD and a history of electroconvulsive therapy (ECT)-induced mania. Six treatments of rTMS were administered at 5 Hz for a total of 3000 pulses per day, when the patient began to display multiple hypomanic symptoms. These symptoms decreased after the termination of treatment and abated within a couple of days. In conclusion, caution should be used when administering rTMS to patients with a history of ECT-induced mania. PMID:24715970

Philip, Noah S.

2013-01-01

281

Changes in regional cerebral blood flow after repetitive transcranial magnetic stimulation of the left dorsolateral prefrontal cortex in treatment-resistant depression.  

PubMed

High-frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex is effective in treatment-resistant depression, although its mechanism is still not completely elucidated. To clarify the neuroanatomical alteration of function elicited by rTMS, single photon emission computed tomography (SPECT) with (99m)Tc-ECD was performed on 12 male inpatients with treatment-resistant unipolar depression before and after high-frequency rTMS of the left dorsolateral prefrontal cortex. These results suggest that the manifestation of the antidepressant effect of high-frequency rTMS is associated with changes in the neuroanatomical function of the left dorsolateral prefrontal cortex as well as of the limbic-paralimbic region, including the ipsilateral subgenual cingulate, and the basal ganglia. PMID:18305287

Kito, Shinsuke; Fujita, Kenichi; Koga, Yoshihiko

2008-01-01

282

Towards dynamic control of magnetic fields to focus magnetic carriers to targets deep inside the body  

PubMed Central

Magnetic drug delivery has the potential to target therapy to specific regions in the body, improving efficacy and reducing side effects for treatment of cancer, stroke, infection, and other diseases. Using stationary external magnets, which attract the magnetic drug carriers, this treatment is limited to shallow targets (<5 cm below skin depth using the strongest possible, still safe, practical magnetic fields). We consider dynamic magnetic actuation and present initial results that show it is possible to vary magnets one against the other to focus carriers between them on average. The many remaining tasks for deep targeting in-vivo are then briefly noted. PMID:20165553

Shapiro, Benjamin

2010-01-01

283

Head-to-Head Comparison of Transcranial Random Noise Stimulation, Transcranial AC Stimulation, and Transcranial DC Stimulation for Tinnitus  

PubMed Central

Tinnitus is the perception of a sound in the absence of an external sound stimulus. This phantom sound has been related to plastic changes and hyperactivity in the auditory cortex. Different neuromodulation techniques such as transcranial magnetic stimulation and transcranial direct current stimulation (tDCS) have been used in an attempt to modify local and distant neuroplasticity as to reduce tinnitus symptoms. Recently, two techniques of pulsed electrical stimulation using weak electrical currents – transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) – have also shown significant neuromodulatory effects. In the present study we conducted the first head-to-head comparison of three different transcranial electrical stimulation (tES) techniques, namely tDCS, tACS, and tRNS in 111 tinnitus patients by placing the electrodes overlying the auditory cortex bilaterally. The results demonstrated that tRNS induced the larger transient suppressive effect on the tinnitus loudness and the tinnitus related distress as compared to tDCS and tACS. Both tDCS and tACS induced small and non-significant effects on tinnitus symptoms, supporting the superior effects of tRNS as a method for tinnitus suppression. PMID:24391599

Vanneste, Sven; Fregni, Felipe; De Ridder, Dirk

2013-01-01

284

Transcranial stimulation and cognition.  

PubMed

Noninvasive brain stimulation (NIBS) is a unique method for studying cognitive function. For the study of cognition, NIBS has gained popularity as a complementary method to functional neuroimaging. By bypassing the correlative approaches of standard imaging techniques, it is possible to establish a putative relationship between brain cognition. In fact, functional neuroimaging data cannot demonstrate the actual role of a particular cortical activation in a specific function because an activated area may simply be correlated with task performance, rather than being responsible for it. NIBS can induce a temporary modification of performance only if the stimulated area is causally engaged in the task. In analogy with lesion studies, NIBS can provide information about where and when a particular process occurs. Based on this assumption, NIBS has been used in many different cognitive domains. However, one of the most interesting questions in neuroscience may not be where and when, but how cognitive activity occurs. Beyond localization approaches, NIBS can be employed to study brain mechanisms. NIBS techniques have the potential to influence behavior transiently by altering neuronal activity, which may have facilitatory or inhibitory behavioral effects. NIBS techniques include transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES). TMS has been shown transiently to modulate neural excitability in a manner that is dependent mainly on the timing and frequency of stimulation (high versus low). The mechanism underlying tES is a change in neuronal membrane potentials that appears to be dependent mainly on the direction of current flow (anodal versus cathodal). Nevertheless, the final effects induced by TMS or tES depend on many technical parameters used during stimulation, such as the intensity of stimulation, coil orientation, site of the reference electrode, and time of application. Moreover, an important factor is the possible interactions between these factors and the physiological and cognitive state of the subject. To use NIBS in cognition, it is important to understand not only how NIBS functions but also the brain mechanisms being studied and the features of the area of interest. To describe better the advanced knowledge provided by NIBS in cognition, we will treat each NIBS technique separately and underline the related hypotheses beyond applications. PMID:24112935

Miniussi, Carlo; Ruzzoli, Manuela

2013-01-01

285

Magnetic resonance imaging safety of deep brain stimulator devices.  

PubMed

Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. The presence of an implanted DBS device in a magnetic resonance environment presents potential hazards. These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices. PMID:24112886

Oluigbo, Chima O; Rezai, Ali R

2013-01-01

286

Bilateral repetitive transcranial magnetic stimulation for treatment-resistant depression: a systematic review and meta-analysis of randomized controlled trials  

PubMed Central

There has been concern regarding the use of controversial paradigms for repetitive transcranial magnetic stimulation (rTMS) to manage treatment-resistant depression (TRD). This meta-analysis assessed the efficacy of bilateral rTMS compared with unilateral and sham rTMS in patients with TRD. PubMed, Embase, CENTRAL, PsycINFO, Web of Science, EAGLE and NTIS databases were searched to identify relevant studies, and randomized controlled trials (RCTs) on bilateral rTMS for TRD patients were included. The response was defined as the primary outcome, and remission was the secondary outcome. Ten RCTs that included 634 patients met the eligibility criteria. The risk ratio (RRs) of both the primary and secondary outcomes of bilateral rTMS showed non-significant increases compared to unilateral rTMS (RR=1.01, P=0.93; odds ratio [OR]=0.77, P=0.22). Notably, the RR of the primary bilateral rTMS outcome was significantly increased compared to that for sham rTMS (RR=3.43, P=0.0004). The results of our analysis demonstrated that bilateral rTMS was significantly more effective than sham rTMS but not unilateral rTMS in patients with TRD. Thus, bilateral rTMS may not be a useful paradigm for patients with TRD. PMID:25590350

Zhang, Y.Q.; Zhu, D.; Zhou, X.Y.; Liu, Y.Y.; Qin, B.; Ren, G.P.; Xie, P.

2015-01-01

287

The use of magnetic resonance spectroscopy as a tool for the measurement of bi-hemispheric transcranial electric stimulation effects on primary motor cortex metabolism.  

PubMed

Transcranial direct current stimulation (tDCS) is a neuromodulation technique that has been increasingly used over the past decade in the treatment of neurological and psychiatric disorders such as stroke and depression. Yet, the mechanisms underlying its ability to modulate brain excitability to improve clinical symptoms remains poorly understood. To help improve this understanding, proton magnetic resonance spectroscopy ((1)H-MRS) can be used as it allows the in vivo quantification of brain metabolites such as ?-aminobutyric acid (GABA) and glutamate in a region-specific manner. In fact, a recent study demonstrated that (1)H-MRS is indeed a powerful means to better understand the effects of tDCS on neurotransmitter concentration. This article aims to describe the complete protocol for combining tDCS (NeuroConn MR compatible stimulator) with (1)H-MRS at 3 T using a MEGA-PRESS sequence. We will describe the impact of a protocol that has shown great promise for the treatment of motor dysfunctions after stroke, which consists of bilateral stimulation of primary motor cortices. Methodological factors to consider and possible modifications to the protocol are also discussed. PMID:25490453

Tremblay, Sara; Beaulé, Vincent; Proulx, Sébastien; Lafleur, Louis-Philippe; Doyon, Julien; Marja?ska, Ma?gorzata; Théoret, Hugo

2014-01-01

288

Mechanism of functional recovery after repetitive transcranial magnetic stimulation (rTMS) in the subacute cerebral ischemic rat model: neural plasticity or anti-apoptosis?  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) has been studied increasingly in recent years to determine whether it has a therapeutic benefit on recovery after stroke. However, the underlying mechanisms of rTMS in stroke recovery remain unclear. Here, we evaluated the effect of rTMS on functional recovery and its underlying mechanism by assessing proteins associated with neural plasticity and anti-apoptosis in the peri-lesional area using a subacute cerebral ischemic rat model. Twenty cerebral ischemic rats were randomly assigned to the rTMS or the sham group at post-op day 4. A total of 3,500 impulses with 10 Hz frequency were applied to ipsilesional cortex over a 2-week period. Functional outcome was measured before (post-op day 4) and after rTMS (post-op day 18). The rTMS group showed more functional improvement on the beam balance test and had stronger Bcl-2 and weaker Bax expression on immunohistochemistry compared with the sham group. The expression of NMDA and MAP-2 showed no significant difference between the two groups. These results suggest that rTMS in subacute cerebral ischemia has a therapeutic effect on functional recovery and is associated with an anti-apoptotic mechanism in the peri-ischemic area rather than with neural plasticity. PMID:21904929

Yoon, Kyung Jae; Lee, Yong-Taek; Han, Tai Ryoon

2011-10-01

289

Patients with a major depressive episode responding to treatment with repetitive transcranial magnetic stimulation (rTMS) are resistant to the effects of rapid tryptophan depletion.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) appears to be efficacious in the treatment of major depression based on the results of controlled studies, but little is known about its antidepressant mechanism of action. Mood sensitivity following rapid tryptophan depletion (RTD) has been demonstrated in depressed patients responding to SSRI antidepressants and phototherapy, but not in responders to electroconvulsive therapy (ECT). We sought to study the effects of RTD in patients with major depression responding to a course of treatment with rTMS. Twelve subjects treated successfully with rTMS monotherapy underwent both RTD and sham depletion in a double-blind crossover design. Depressive symptoms were assessed using both a modified Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI). The differential change in depression scores across the procedures was compared. No significant difference in mood symptoms was noted between RTD and the sham-depletion procedure on either continuous measures of depression, or in the proportions of subjects that met predefined criteria for a significant degree of mood worsening. Responders to rTMS are resistant to the mood perturbing effects of RTD. This suggests that rTMS does not depend on the central availability of serotonin to exert antidepressant effects in major depression. PMID:17131353

O'Reardon, John P; Cristancho, Pilar; Pilania, Pramod; Bapatla, Kiran B; Chuai, Shaokun; Peshek, Andrew D

2007-01-01

290

Repetitive Transcranial Magnetic Stimulation Ameliorates Anxiety-Like Behavior and Impaired Sensorimotor Gating in a Rat Model of Post-Traumatic Stress Disorder  

PubMed Central

Background Repetitive transcranial magnetic stimulation (rTMS) has been employed for decades as a non-pharmacologic treatment for post-traumatic stress disorder (PTSD). Although a link has been suggested between PTSD and impaired sensorimotor gating (SG), studies assessing the effects of rTMS against PTSD or PTSD with impaired SG are scarce. Aim To assess the benefit of rTMS in a rat model of PTSD. Methods Using a modified single prolonged stress (SPS&S) rat model of PTSD, behavioral parameters were acquired using open field test (OFT), elevated plus maze test (EPMT), and prepulse inhibition trial (PPI), with or without 7 days of high frequency (10Hz) rTMS treatment of SPS&S rats. Results Anxiety-like behavior, impaired SG and increased plasma level of cortisol were observed in SPS&S animals after stress for a prolonged time. Interestingly, rTMS administered immediately after stress prevented those impairment. Conclusion Stress-induced anxiety-like behavior, increased plasma level of cortisol and impaired PPI occur after stress and high-frequency rTMS has the potential to ameliorate this behavior, suggesting that high frequency rTMS should be further evaluated for its use as a method for preventing PTSD. PMID:25659132

Wang, Hua-ning; Bai, Yuan-han; Chen, Yun-chun; Zhang, Rui-guo; Wang, Huai-hai; Zhang, Ya-hong; Gan, Jing-li; Peng, Zheng-wu; Tan, Qing-rong

2015-01-01

291

Repeated mapping of cortical language sites by preoperative navigated transcranial magnetic stimulation compared to repeated intraoperative DCS mapping in awake craniotomy  

PubMed Central

Background Repetitive navigated transcranial magnetic stimulation (rTMS) was recently described for mapping of human language areas. However, its capability of detecting language plasticity in brain tumor patients was not proven up to now. Thus, this study was designed to evaluate such data in order to compare rTMS language mapping to language mapping during repeated awake surgery during follow-up in patients suffering from language-eloquent gliomas. Methods Three right-handed patients with left-sided gliomas (2 opercular glioblastomas, 1 astrocytoma WHO grade III of the angular gyrus) underwent preoperative language mapping by rTMS as well as intraoperative language mapping provided via direct cortical stimulation (DCS) for initial as well as for repeated Resection 7, 10, and 15 months later. Results Overall, preoperative rTMS was able to elicit clear language errors in all mappings. A good correlation between initial rTMS and DCS results was observed. As a consequence of brain plasticity, initial DCS and rTMS findings only corresponded with the results obtained during the second examination in one out of three patients thus suggesting changes of language organization in two of our three patients. Conclusions This report points out the usefulness but also the limitations of preoperative rTMS language mapping to detect plastic changes in language function or for long-term follow-up prior to DCS even in recurrent gliomas. However, DCS still has to be regarded as gold standard. PMID:24479694

2014-01-01

292

Functional Interaction between Right Parietal and Bilateral Frontal Cortices during Visual Search Tasks Revealed Using Functional Magnetic Imaging and Transcranial Direct Current Stimulation  

PubMed Central

The existence of a network of brain regions which are activated when one undertakes a difficult visual search task is well established. Two primary nodes on this network are right posterior parietal cortex (rPPC) and right frontal eye fields. Both have been shown to be involved in the orientation of attention, but the contingency that the activity of one of these areas has on the other is less clear. We sought to investigate this question by using transcranial direct current stimulation (tDCS) to selectively decrease activity in rPPC and then asking participants to perform a visual search task whilst undergoing functional magnetic resonance imaging. Comparison with a condition in which sham tDCS was applied revealed that cathodal tDCS over rPPC causes a selective bilateral decrease in frontal activity when performing a visual search task. This result demonstrates for the first time that premotor regions within the frontal lobe and rPPC are not only necessary to carry out a visual search task, but that they work together to bring about normal function. PMID:24705681

Ellison, Amanda; Ball, Keira L.; Moseley, Peter; Dowsett, James; Smith, Daniel T.; Weis, Susanne; Lane, Alison R.

2014-01-01

293

Effect of low frequency repetitive transcranial magnetic stimulation on kindling-induced changes in electrophysiological properties of rat CA1 pyramidal neurons.  

PubMed

In this study, the effect of repetitive transcranial magnetic stimulation (rTMS) on the kindling induced changes in electrophysiological firing properties of hippocampal CA1 pyramidal neurons was investigated. Male Wistar rats were kindled by daily electrical stimulation of the basolateral amygdala in a semi-rapid manner (12 stimulations/day) until they achieved stage-5 seizure. One group (kindled+rTMS (KrTMS)) of animals received rTMS (240 pulses at 1Hz) at 5min after termination of daily kindling stimulations. Twenty-four hours following the last kindling stimulation electrophysiological properties of hippocampal CA1 pyramidal neurons were investigated using a whole-cell patch clamp technique, under current clamp condition. Amygdala kindling significantly decreased the adaptation index, post-afterhyperpolarization, rheobase current, utilization time, and delay to the first rebound spike. It also caused an increase in the voltage sag, number of rebound spikes and number of evoked action potential. Results of the present study revealed that application of rTMS following kindling stimulations had antiepileptogenic effects. In addition, application of rTMS prevented hyperexcitability of CA1 pyramidal neurons induced by kindling and conserved the normal neuronal firing. PMID:25721786

Moradi Chameh, Homeira; Janahmadi, Mahyar; Semnanian, Saeed; Shojaei, Amir; Mirnajafi-Zadeh, Javad

2015-05-01

294

Benefits of Repetitive Transcranial Magnetic Stimulation (rTMS) for Spastic Subjects: Clinical, Functional, and Biomechanical Parameters for Lower Limb and Walking in Five Hemiparetic Patients  

PubMed Central

Introduction. Spasticity is a disabling symptom resulting from reorganization of spinal reflexes no longer inhibited by supraspinal control. Several studies have demonstrated interest in repetitive transcranial magnetic stimulation in spastic patients. We conducted a prospective, randomized, double-blind crossover study on five spastic hemiparetic patients to determine whether this type of stimulation of the premotor cortex can provide a clinical benefit. Material and Methods. Two stimulation frequencies (1?Hz and 10?Hz) were tested versus placebo. Patients were assessed clinically, by quantitative analysis of walking and measurement of neuromechanical parameters (H and T reflexes, musculoarticular stiffness of the ankle). Results. No change was observed after placebo and 10?Hz protocols. Clinical parameters were not significantly modified after 1?Hz stimulation, apart from a tendency towards improved recruitment of antagonist muscles on the Fügl-Meyer scale. Only cadence and recurvatum were significantly modified on quantitative analysis of walking. Neuromechanical parameters were modified with significant decreases in Hmax? /Mmax? and T/Mmax? ratios and stiffness indices 9 days or 31 days after initiation of TMS. Conclusion. This preliminary study supports the efficacy of low-frequency TMS to reduce reflex excitability and stiffness of ankle plantar flexors, while clinical signs of spasticity were not significantly modified. PMID:24883390

Gross, Raphael; Leboeuf, Fabien; Desal, Hubert; Hamel, Olivier; Nguyen, Jean Paul; Pérot, Chantal; Buffenoir, Kévin

2014-01-01

295

Comparing the Effects of Repetitive Transcranial Magnetic Stimulation and Electroconvulsive Therapy in the Treatment of Depression: A Systematic Review and Meta-Analysis  

PubMed Central

Electroconvulsive therapy (ECT) is the longest standing psychiatric treatment available and has unequivocal benefit in severe depression. However this treatment comes with a number of side effects such as memory impairment. On the other hand, Repetitive Transcranial Magnetic Stimulation (rTMS) is a relatively new form of treatment which has been shown to be efficacious in patients suffering from a number of psychopathologies, including severe depression, with few reported side effects. Due to its potential therapeutic efficacy and lack of side effects, rTMS has gained traction in the treatment of depression, with a number of authors keen to see it take over from ECT. However, it is not clear whether rTMS represents a therapeutic alternative to ECT. This meta-analysis will therefore compare the “gold standard” treatment for severe depression, with the relatively new but promising rTMS. A literature search will be performed with the intention to include all randomised clinical trials. The null hypothesis is that there is no difference in the antidepressant efficacy between the two types of treatment modalities. Statistical analysis of Hamilton Depression Rating Scale (HDRS) scores will be performed. PMID:25143831

2014-01-01

296

Changes in hypothalamic-pituitary-thyroid axis following successful treatment with low-frequency right prefrontal transcranial magnetic stimulation in treatment-resistant depression.  

PubMed

Hypothalamic-pituitary-thyroid (HPT) axis abnormalities have been reported in some patients with major depression. To knowledge, however, the effects of low-frequency right prefrontal transcranial magnetic stimulation (TMS) on the HPT axis have not yet been elucidated. The goal of this study was to evaluate alterations in the HPT axis associated with the therapeutic efficacy of TMS treatments. Twenty patients with treatment-resistant depression received five 60-s 1-Hz trains over the right dorsolateral prefrontal cortex. Twelve treatment sessions were administered within a 3-week period (total pulses, 3600). Responders were defined as a > or =50% decrease in the Hamilton Depression Rating Scale (HDRS) score. Serum levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) were measured, respectively, at pre- and post-treatment. There were no significant changes in fT3 and fT4 levels measured at either pre- or post-treatment in either responders or nonresponders; however, TSH levels of responders elevated significantly after TMS treatments. In addition, there was a significant negative correlation between TSH levels at pretreatment and decrease (%) in the HDRS score. These findings suggest that the HPT axis is associated with antidepressant effects of low-frequency right prefrontal TMS, and indicate that lower TSH levels at pre-treatment are correlated with better therapeutic efficacy. PMID:20004482

Kito, Shinsuke; Hasegawa, Takashi; Fujita, Kenichi; Koga, Yoshihiko

2010-01-30

297

The role of the right dorsolateral prefrontal cortex in the Tower of London task performance: repetitive transcranial magnetic stimulation study in patients with Parkinson's disease.  

PubMed

We studied whether one session of high-frequency repetitive transcranial magnetic stimulation (rTMS) applied over either the right or left dorsolateral prefrontal cortex would induce any measurable changes in the Tower of London spatial planning task performance in patients with Parkinson's disease (PD). Ten patients with PD (with no dementia and/or depression) entered the randomized, sham-stimulation-controlled study with a crossover design. Active and placebo rTMS were applied over either the left or the right dorsolateral prefrontal cortex (in four separate sessions) in each patient. The order of sessions was randomized. The Tower of London task was performed prior to and immediately after each appropriate session. The "total problem-solving time" was our outcome measure. Only active rTMS of the right dorsolateral prefrontal cortex induced significant enhancement of the total problem-solving time, p = 0.038. Stimulation of the left prefrontal cortex or sham stimulations induced no significant effects. Only rTMS applied over the right dorsolateral prefrontal cortex induced positive changes in the spatial planning task performance in PD, which further supports the results of functional imaging studies indicating the causal engagement of the right-sided hemispheric structures in solving the task in this patient population. PMID:22975864

Srovnalova, H; Marecek, R; Kubikova, R; Rektorova, I

2012-11-01

298

Naming facilitation induced by transcranial direct current stimulation  

Microsoft Academic Search

Transcranial direct current stimulation (tDCS) is able to generate a long-term increase or decrease in the neuronal excitability that can modulate cognitive tasks, similar to repetitive transcranial magnetic stimulation. The aim of this study was to explore the effects of tDCS on a language task in young healthy subjects. Anodal, cathodal and sham tDCS were applied to the left dorsolateral

Anna Fertonani; Sandra Rosini; Maria Cotelli; Paolo Maria Rossini; Carlo Miniussi

2010-01-01

299

Whole-Body Water Flow Stimulation to the Lower Limbs Modulates Excitability of Primary Motor Cortical Regions Innervating the Hands: A Transcranial Magnetic Stimulation Study  

PubMed Central

Whole-body water immersion (WI) has been reported to change sensorimotor integration. However, primary motor cortical excitability is not affected by low-intensity afferent input. Here we explored the effects of whole-body WI and water flow stimulation (WF) on corticospinal excitability and intracortical circuits. Eight healthy subjects participated in this study. We measured the amplitude of motor-evoked potentials (MEPs) produced by single transcranial magnetic stimulation (TMS) pulses and examined conditioned MEP amplitudes by paired-pulse TMS. We evaluated short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) using the paired-TMS technique before and after 15-min intervention periods. Two interventions used were whole-body WI with water flow to the lower limbs (whole-body WF) and whole-body WI without water flow to the lower limbs (whole-body WI). The experimental sequence included a baseline TMS assessment (T0), intervention for 15 min, a second TMS assessment immediately after intervention (T1), a 10 min resting period, a third TMS assessment (T2), a 10 min resting period, a fourth TMS assessment (T3), a 10 min resting period, and the final TMS assessment (T4). SICI and ICF were evaluated using a conditioning stimulus of 90% active motor threshold and a test stimulus adjusted to produce MEPs of approximately 1–1.2 mV, and were tested at intrastimulus intervals of 3 and 10 ms, respectively. Whole-body WF significantly increased MEP amplitude by single-pulse TMS and led to a decrease in SICI in the contralateral motor cortex at T1, T2 and T3. Whole-body WF also induced increased corticospinal excitability and decreased SICI. In contrast, whole-body WI did not change corticospinal excitability or intracortical circuits. PMID:25025129

Sato, Daisuke; Yamashiro, Koya; Onishi, Hideaki; Baba, Yasuhiro; Nakazawa, Sho; Shimoyama, Yoshimitsu; Maruyama, Atsuo

2014-01-01

300

Repetitive transcranial magnetic stimulation promotes neural stem cell proliferation via the regulation of MiR-25 in a rat model of focal cerebral ischemia.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) has increasingly been studied over the past decade to determine whether it has a therapeutic benefit on focal cerebral ischemia. However, the underlying mechanism of rTMS in this process remains unclear. In the current study, we investigated the effects of rTMS on the proliferation of adult neural stem cells (NSCs) and explored microRNAs (miRNAs) that were affected by rTMS. Our data showed that 10 Hz rTMS significantly increased the proliferation of adult NSCs after focal cerebral ischemia in the subventricular zone (SVZ), and the expression of miR-25 was obviously up-regulated in the ischemic cortex after rTMS. p57, an identified miR-25 target gene that regulates factors linked to NSC proliferation, was also evaluated, and it exhibited down-regulation. To further verify the role of miR-25, rats were injected with a single dose of antagomir-25 and were subjected to focal cerebral ischemia followed by rTMS treatment. The results confirmed that miR-25 could be repressed specifically and could drive the up-regulation of its target gene (p57), which resulted in the inhibition of adult NSC proliferation in the SVZ after rTMS. Thus, our studies strongly indicated that 10 Hz rTMS can promote the proliferation of adult NSCs in the SVZ after focal cerebral ischemia by regulating the miR-25/p57 pathway. PMID:25302788

Guo, Feng; Han, Xiaohua; Zhang, Jinghui; Zhao, Xiuxiu; Lou, Jicheng; Chen, Hong; Huang, Xiaolin

2014-01-01

301

Short and Long Term Effects of Left and Bilateral Repetitive Transcranial Magnetic Stimulation in Schizophrenia Patients with Auditory Verbal Hallucinations: A Randomized Controlled Trial  

PubMed Central

Background Repetitive transcranial magnetic stimulation of the left temporo-parietal junction area has been studied as a treatment option for auditory verbal hallucinations. Although the right temporo-parietal junction area has also shown involvement in the genesis of auditory verbal hallucinations, no studies have used bilateral stimulation. Moreover, little is known about durability effects. We studied the short and long term effects of 1 Hz treatment of the left temporo-parietal junction area in schizophrenia patients with persistent auditory verbal hallucinations, compared to sham stimulation, and added an extra treatment arm of bilateral TPJ area stimulation. Methods In this randomized controlled trial, 51 patients diagnosed with schizophrenia and persistent auditory verbal hallucinations were randomly allocated to treatment of the left or bilateral temporo-parietal junction area or sham treatment. Patients were treated for six days, twice daily for 20 minutes. Short term efficacy was measured with the Positive and Negative Syndrome Scale (PANSS), the Auditory Hallucinations Rating Scale (AHRS), and the Positive and Negative Affect Scale (PANAS). We included follow-up measures with the AHRS and PANAS at four weeks and three months. Results The interaction between time and treatment for Hallucination item P3 of the PANSS showed a trend for significance, caused by a small reduction of scores in the left group. Although self-reported hallucination scores, as measured with the AHRS and PANAS, decreased significantly during the trial period, there were no differences between the three treatment groups. Conclusion We did not find convincing evidence for the efficacy of left-sided rTMS, compared to sham rTMS. Moreover, bilateral rTMS was not superior over left rTMS or sham in improving AVH. Optimizing treatment parameters may result in stronger evidence for the efficacy of rTMS treatment of AVH. Moreover, future research should consider investigating factors predicting individual response. Trial Registration Dutch Trial Register NTR1813 PMID:25329799

Bais, Leonie; Vercammen, Ans; Stewart, Roy; van Es, Frank; Visser, Bert; Aleman, André; Knegtering, Henderikus

2014-01-01

302

Preconditioning repetitive transcranial magnetic stimulation of premotor cortex can reduce but not enhance short-term facilitation of primary motor cortex.  

PubMed

Short trains of suprathreshold 5-Hz repetitive transcranial magnetic stimulation (rTMS) over primary motor cortex (M1) evoke motor potentials (MEPs) in hand muscles that progressively increase in amplitude via a mechanism that is thought to be similar to short-term potentiation described in animal preparations. Long trains of subthreshold rTMS over dorsal premotor cortex (PMd) are known to affect the amplitude of single-pulse MEPs evoked from M1. We tested whether PMd-rTMS affects short-term facilitation in M1. We also explored the effect of PMd-rTMS on M1 responses evoked by single-pulse TMS of different polarities. We tested in 15 healthy subjects short-term facilitation in left M1 (10 suprathreshold TMS pulses at 5 Hz) after applying rTMS to left PMd (1,500 subthreshold pulses at 1 and 5 Hz). In a sample of subjects we delivered single-pulse TMS with different polarities and paired-pulse TMS at short intervals (SICI) after PMd-rTMS. Short-term facilitation in M1 was reduced after applying 1 Hz to PMd, but was unaffected after 5-Hz PMd-rTMS. PMd-rTMS with 1 Hz reduced the amplitude of MEPs evoked by monophasic posteroanterior (PA) or biphasic anteroposterior (AP)-PA but had little effect on MEPs by monophasic AP or biphasic PA-AP single-pulse TMS. PMd-rTMS left SICI unchanged. PMd-rTMS (1 Hz) reduces short-term facilitation in M1 induced by short 5-Hz trains. This effect is likely to be caused by reduced facilitation of I-wave inputs to corticospinal neurons. PMID:18057113

Suppa, A; Bologna, M; Gilio, F; Lorenzano, C; Rothwell, J C; Berardelli, A

2008-02-01

303

Repetitive Transcranial Magnetic Stimulation Promotes Neural Stem Cell Proliferation via the Regulation of MiR-25 in a Rat Model of Focal Cerebral Ischemia  

PubMed Central

Repetitive transcranial magnetic stimulation (rTMS) has increasingly been studied over the past decade to determine whether it has a therapeutic benefit on focal cerebral ischemia. However, the underlying mechanism of rTMS in this process remains unclear. In the current study, we investigated the effects of rTMS on the proliferation of adult neural stem cells (NSCs) and explored microRNAs (miRNAs) that were affected by rTMS. Our data showed that 10 Hz rTMS significantly increased the proliferation of adult NSCs after focal cerebral ischemia in the subventricular zone (SVZ), and the expression of miR-25 was obviously up-regulated in the ischemic cortex after rTMS. p57, an identified miR-25 target gene that regulates factors linked to NSC proliferation, was also evaluated, and it exhibited down-regulation. To further verify the role of miR-25, rats were injected with a single dose of antagomir-25 and were subjected to focal cerebral ischemia followed by rTMS treatment. The results confirmed that miR-25 could be repressed specifically and could drive the up-regulation of its target gene (p57), which resulted in the inhibition of adult NSC proliferation in the SVZ after rTMS. Thus, our studies strongly indicated that 10 Hz rTMS can promote the proliferation of adult NSCs in the SVZ after focal cerebral ischemia by regulating the miR-25/p57 pathway. PMID:25302788

Zhang, Jinghui; Zhao, Xiuxiu; Lou, Jicheng; Chen, Hong; Huang, Xiaolin

2014-01-01

304

Moderate therapeutic efficacy of positron emission tomography?navigated repetitive transcranial magnetic stimulation for chronic tinnitus: a randomised, controlled pilot study  

PubMed Central

Background Tinnitus has been shown to respond to modulations of cortical activity by high?frequency and low?frequency repetitive transcranial magnetic stimulation (rTMS). Objective To determine the tinnitus?attenuating effects of a 2?week daily regimen of rTMS, navigated to the maximum of tinnitus?related increase in regional cerebral blood flow. Methods Six patients with chronic tinnitus were enrolled in this sham?controlled crossover study and treated with 2×2?weeks of suprathreshold 1?Hz rTMS (30?min) applied to the region with maximal tinnitus?related increase in regional cerebral blood flow delineated by functional imaging with [15O]H2O positron emission tomography and a control area. Tinnitus?related distress was assessed before and after each treatment and 2?weeks after the end of the 4?week course of stimulation using a validated tinnitus questionnaire. Additional self?assessment scores of tinnitus change, loudness and annoyance were obtained. Results In five of six patients, rTMS induced greater reduction of the tinnitus questionnaire score than sham stimulation. In two patients, all parameters measured (tinnitus change score, tinnitus loudness, tinnitus annoyance) showed unequivocal improvement. At the group level, the degree of response in the tinnitus questionnaire score was correlated with tinnitus?associated activation of the anterior cingulate cortex. Two weeks after the final stimulation, tinnitus had returned to baseline in all patients but one. Conclusion Tinnitus can be attenuated by low?frequency rTMS navigated to each person's maximum tinnitus?related cortical hyperactivity. The effects are only moderate; interindividual responsiveness varies and the attenuation seems to wear off within 2?weeks after the last stimulation session. Notably, tinnitus?related anterior cingulate cortex activation seems to predict the response to rTMS treatment. PMID:16891384

Plewnia, C; Reimold, M; Najib, A; Reischl, G; Plontke, S K; Gerloff, C

2007-01-01

305

Repetitive transcranial magnetic stimulation improves open field locomotor recovery after low but not high thoracic spinal cord compression-injury in adult rats.  

PubMed

Electromagnetic fields are able to promote axonal regeneration in vitro and in vivo. Repetitive transcranial magnetic stimulation (rTMS) is used routinely in neuropsychiatric conditions and as an atraumatic method to activate descending motor pathways. After spinal cord injury, these pathways are disconnected from the spinal locomotor generator, resulting in most of the functional deficit. We have applied daily 10 Hz rTMS for 8 weeks immediately after an incomplete high (T4-5; n = 5) or low (T10-11; n = 6) thoracic closed spinal cord compression-injury in adult rats, using 6 high- and 6 low-lesioned non-stimulated animals as controls. Functional recovery of hindlimbs was assessed using the BBB locomotor rating scale. In the control group, the BBB score was significantly better from the 7th week post-injury in animals lesioned at T4-5 compared to those lesioned at T10-11. rTMS significantly improved locomotor recovery in T10-11-injured rats, but not in rats with a high thoracic injury. In rTMS-treated rats, there was significant positive correlation between final BBB score and grey matter density of serotonergic fibres in the spinal segment just caudal to the lesion. We propose that low thoracic lesions produce a greater functional deficit because they interfere with the locomotor centre and that rTMS is beneficial in such lesions because it activates this central pattern generator, presumably via descending serotonin pathways. The benefits of rTMS shown here suggest strongly that this non-invasive intervention strategy merits consideration for clinical trials in human paraplegics with low spinal cord lesions. PMID:14705146

Poirrier, Anne-Lise; Nyssen, Yves; Scholtes, Felix; Multon, Sylvie; Rinkin, Charline; Weber, Géraldine; Bouhy, Delphine; Brook, Gary; Franzen, Rachelle; Schoenen, Jean

2004-01-15

306

Whole-hand water flow stimulation increases motor cortical excitability: a study of transcranial magnetic stimulation and movement-related cortical potentials.  

PubMed

Previous studies examining the influence of afferent stimulation on corticospinal excitability have demonstrated that the intensity of afferent stimulation and the nature of the afferents targeted (cutaneous/proprioceptive) determine the effects. In this study, we assessed the effects of whole-hand water immersion (WI) and water flow stimulation (WF) on corticospinal excitability and intracortical circuits by measuring motor evoked potential (MEP) recruitment curves and conditioned MEP amplitudes. We further investigated whether whole-hand WF modulated movement-related cortical activity. Ten healthy subjects participated in three experiments, comprising the immersion of participants' right hands with (whole-hand WF) or without (whole-hand WI) water flow, and no immersion (control). We evaluated MEP recruitment curves produced by a single transcranial magnetic stimulation (TMS) pulse at increasing stimulus intensities, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) using the paired TMS technique before and after 15 min of intervention. Movement-related cortical potentials (MRCPs) were evaluated to examine primary motor cortex, supplementary motor area, and somatosensory cortex excitability upon movement before and after whole-hand WF. After whole-hand WF, the slope of the MEP recruitment curve significantly increased, whereas SICI decreased and ICF increased in the contralateral motor cortex. The amplitude of the Bereitschaftspotential, negative slope, and motor potential of MRCPs significantly increased after whole-hand WF. We demonstrated that whole-hand WF increased corticospinal excitability, decreased SICI, and increased ICF, although whole-hand WI did not change corticospinal excitability and intracortical circuits. Whole-hand WF modulated movement-related cortical activity, increasing motor cortex activation for the planning and execution of voluntary movements. PMID:25376780

Sato, Daisuke; Yamashiro, Koya; Onishi, Hideaki; Yasuhiro, Baba; Shimoyama, Yoshimitsu; Maruyama, Atsuo

2015-02-01

307

Regional cerebral blood flow changes after low-frequency transcranial magnetic stimulation of the right dorsolateral prefrontal cortex in treatment-resistant depression.  

PubMed

Several studies have proved that low-frequency transcranial magnetic stimulation (TMS) of the right dorsolateral prefrontal cortex (DLPFC) showed an antidepressant effect, although its mechanism is still not completely elucidated. The aim of the present study was to clarify the alteration in neuroanatomical function elicited by low-frequency TMS of the right DLPFC in treatment-resistant depression and to detect the difference between responders and nonresponders to TMS. Single-photon emission computed tomography with (99m)Tc-ethyl cysteinate dimer was performed in 14 right-handed male patients with treatment-resistant unipolar depression before and after low-frequency TMS of the right DLPFC. Five 60-second 1-Hz trains were applied and 12 treatment sessions were administered within a 3-week period (total pulses, 3,600). The Hamilton Rating Scale for Depression was administered and the regional cerebral blood flow (rCBF) was analyzed using statistical parametric mapping (SPM2). After TMS treatment in 14 patients, the score on the Hamilton Rating Scale for Depression decreased significantly, and considerable decreases in rCBF were seen in the bilateral prefrontal, orbitofrontal, anterior insula, right subgenual cingulate, and left parietal cortex, but no significant increase in rCBF occurred. Additionally, as compared with 8 nonresponders, 6 responders showed significant increases in rCBF at baseline in the left hemisphere including the prefrontal and limbic-paralimbic regions. These results suggest that the antidepressant effect of low-frequency TMS of the right DLPFC is associated with a decrease in rCBF in the limbic-paralimbic regions via the ipsilateral subgenual cingulate, and increased rCBF at baseline in the left hemisphere may be involved in the response to low-frequency TMS treatment. PMID:18781088

Kito, Shinsuke; Fujita, Kenichi; Koga, Yoshihiko

2008-01-01

308

Safety and tolerability of theta burst stimulation vs. single and paired pulse transcranial magnetic stimulation: a comparative study of 165 pediatric subjects  

PubMed Central

Background: Although single- and paired-pulse (sp/pp) transcranial magnetic stimulation (TMS) studies are considered minimal risk in adults and children, the safety profile for theta-burst TMS (TBS) is unknown. Objective: In this comparative analysis, we explored the rate, severity, and specific symptoms of TMS-related adverse effects (AEs) between sp/ppTMS and TBS in subjects between ages 6 and 18 years. Method: Data from 165 participants from 2009 to 2014 were analyzed. Assessment of AEs was performed based on baseline and post-TMS administration of a symptom-based questionnaire that rated AEs on a 5-level ordinal scale (minimal, mild, moderate, marked, severe). AE rates and severity were compared using Chi Square or Fisher’s Exact Test depending on data characteristics. Result: Overall, no seizures or severe-rated AEs were reported by 165 pediatric participants. The rate of AE in all TBS sessions was 10.5% (n = 76, 95% CI: 4.7–19.7%), whereas the rate of AE in all sp/ppTMS sessions was 12.4% (n = 89, 95% CI: 6.3–21.0%). There was no statistical difference in AE rates between TBS and sp/ppTMS (p = 0.71). In all sp/ppTMS and TBS sessions, 20 subjects reported a total of 35 AEs, among these 31 (~88.6%) were rated as “minimal” or “mild”. There was no difference in the severity of AE between TBS and sp/ppTMS (p = 1.0). Only one of 76 TBS participants reported an AE rated as more than minimal/mild. Conclusion: Our comparative analysis showed that TBS appears to be as safe as sp/ppTMS in terms of AE rate and severity. This report supports further investigation of TBS in children. PMID:25698958

Hong, Yaejee H.; Wu, Steve W.; Pedapati, Ernest V.; Horn, Paul S.; Huddleston, David A.; Laue, Cameron S.; Gilbert, Donald L.

2015-01-01

309

Hand position-dependent modulation of errors in vibrotactile temporal order judgments: the effects of transcranial magnetic stimulation to the human posterior parietal cortex.  

PubMed

The ability to decide which of the two stimuli is presented first can be probed using a temporal order judgment (TOJ) task. When the stimuli are delivered to the fingers, TOJ decisions can be confounded by the fact that the hands can be moved to different locations in space. How and where this confounded information is processed in the brain is poorly understood. In the present set of experiments, we addressed this knowledge gap by using single-pulse transcranial magnetic stimulation (TMS) to disrupt processing in the right or left posterior parietal cortex (PPC) during a vibrotactile TOJ task with stimuli applied to the right and left index fingers. In the first experiment, participants held their hands in an uncrossed configuration, and we found that when the index finger contralateral to the site of TMS was stimulated first, there was a significant increase in TOJ errors. This increase did not occur when stimuli were delivered to the ipsilateral finger first. In the second experiment, participants held their hands in a crossed configuration and the pattern of errors was reversed relative to the first experiment. In both the first two experiments, significant increases in TOJ error were present with TMS over either hemisphere, regardless of arm configuration; however, they were larger overall following TMS over the right PPC. Control experiments using sham TMS indicated the systematic modulation in error was not due to nonspecific effects of the stimulation. Additionally, we showed that these TMS-induced changes in TOJ errors were not due to a reduced ability to detect the timing of the vibrotactile stimuli. Taken together, these results demonstrate that both the right and left PPC contribute to the processing underlying vibrotactile TOJs by integrating vibrotactile information and proprioceptive information related to arm position in space. PMID:24562409

Ritterband-Rosenbaum, Anina; Hermosillo, Robert; Kroliczak, Gregory; van Donkelaar, Paul

2014-06-01

310

Small-animal repetitive transcranial magnetic stimulation combined with [¹?F]-FDG microPET to quantify the neuromodulation effect in the rat brain.  

PubMed

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neurostimulation technique for the treatment of various neurological and psychiatric disorders. To investigate the working mechanism of this treatment approach, we designed a small-animal coil for dedicated use in rats and we combined this neurostimulation method with small-animal positron emission tomography (microPET or ?PET) to quantify regional 2-deoxy-2-((18)F)fluoro-d-glucose ([(18)F]-FDG) uptake in the rat brain, elicited by a low- (1 Hz) and a high- (50 Hz) frequency paradigm. Rats (n=6) were injected with 1 mCi of [(18)F]-FDG 10 min after the start of 30 min of stimulation (1 Hz, 50 Hz or sham), followed by a 20-min ?PET image acquisition. Voxel-based statistical parametric mapping (SPM) image analysis of 1-Hz and 50-Hz versus sham stimulation was performed. For both the 1-Hz and 50-Hz paradigms we found a large [(18)F]-FDG hypermetabolic cluster (2.208 mm(3) and 2.616 mm(3), resp.) (analysis of variance (ANOVA), p<0.05) located in the dentate gyrus complemented with an additional [(18)F]-FDG hypermetabolic cluster (ANOVA, p<0.05) located in the entorhinal cortex (2.216 mm(3)) for the 50-Hz stimulation. The effect on [(18)F]-FDG metabolism was 2.9 ± 0.8% at 1 Hz and 2.5 ± 0.8% at 50 Hz for the dentate gyrus clusters and 3.3 ± 0.5% for the additional cluster in the entorhinal cortex at 50 Hz. The maximal (4.19 vs. 2.58) and averaged (2.87 vs. 2.21) T-values are higher for 50 Hz versus 1 Hz. This experimental study demonstrates the feasibility to combine ?PET imaging in rats stimulated with rTMS using a custom-made small-animal magnetic stimulation setup to quantify changes in the cerebral [(18)F]-FDG uptake as a measure for neuronal activity. PMID:24979056

Parthoens, J; Verhaeghe, J; Wyckhuys, T; Stroobants, S; Staelens, S

2014-09-01

311

Deep-tow study of magnetic anomalies in the Pacific Jurassic Quiet Zone  

E-print Network

The Jurassic Quiet Zone (JQZ) is a region of low amplitude, difficult-to-correlate magnetic anomalies located over Jurassic oceanic crust. We collected 1200 km of new deep-tow magnetic anomaly profiles over the Pacific JQZ that complement 2 deep...

Tominaga, Masako

2006-10-30

312

Low Frequency Repetitive Transcranial Magnetic Stimulation to Improve Motor Function and Grip Force of Upper Limbs of Patients With Hemiplegia  

PubMed Central

Background: Stroke is the most common and debilitating neurological disorder among adults, and is a sudden onset of neurological signs caused by brain blood vessels impairments. Objectives: Some new therapeutic methods focus on the use of magnetic stimulation to produce therapeutic effects by inducing the currents. The aim of this study is to determine the effects of rTMS plus routine rehabilitation on hand grip and wrist motor functions in patients with hemiplegia, and compare with pure routine rehabilitation programs. Patients and Methods: In this study, 12 patients with hemiplegia were randomly divided in two groups. Control group, received the rehabilitation program with placebo magnetic stimulation, and the experimental group, received magnetic stimulation with routine rehabilitation program for 10 sessions for three times per week. Pre and post evaluations of treatment performed using Barthel and Fugl-Meyer indices and dynamometers. Results: In the control group, Barthel and Fugl-Meyer indices showed significant improvement (P = 0.01, P = 0.00), while in the experimental group, significant improvement in Barthel and Fugl-Meyer indices and dynamometers has been observed (P = 0.01, P = 0.00, P = 0.007). Conclusions: rTMS can improve hand muscle force and functions of patients with chronic hemiplegia, while conventional treatment is not effective. PMID:25389476

Motamed Vaziri, Poopak; Bahrpeyma, Farid; Firoozabadi, Mohammad; Forough, Bijan; Hatef, Boshra; Sheikhhoseini, Rahman; Shamili, Aryan

2014-01-01

313

Effects of transcranial direct current stimulation coupled with repetitive electrical stimulation on cortical spreading depression  

Microsoft Academic Search

We have recently shown that two techniques of brain stimulation – repetitive electrical stimulation (ES) (that mimics transcranial magnetic stimulation) and transcranial direct current stimulation (tDCS) – modify the velocity of cortical spreading depression (CSD) significantly. Herein we aimed to study the effects of these two techniques combined on CSD. Thirty-two Wistar rats were divided into four groups according to

Felipe Fregni; David Liebetanz; Katia K. Monte-Silva; Manuella B. Oliveira; Angela A. Santos; Michael A. Nitsche; Alvaro Pascual-Leone; Rubem C. A. Guedes

2007-01-01

314

Effects of transcranial direct current stimulation on working memory in patients with Parkinson's disease  

Microsoft Academic Search

ObjectivesCognitive impairment is a common feature in Parkinson's disease (PD) and is an important predictor of quality of life. Past studies showed that some aspects of cognition, such as working memory, can be enhanced following dopaminergic therapy and transcranial magnetic stimulation. The aim of our study was to investigate whether another form of noninvasive brain stimulation, anodal transcranial direct current

Paulo S. Boggio; Roberta Ferrucci; Sergio P. Rigonatti; Priscila Covre; Michael Nitsche; Alvaro Pascual-Leone; Felipe Fregni

2006-01-01

315

Cathodal Transcranial Direct Current Stimulation of the Right Wernicke's Area Improves Comprehension in Subacute Stroke Patients  

ERIC Educational Resources Information Center

Previous studies have shown the appearance of right-sided language-related brain activity in right-handed patients after a stroke. Non-invasive brain stimulation such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) have been shown to modulate excitability in the brain. Moreover, rTMS and…

You, Dae Sang; Kim, Dae-Yul; Chun, Min Ho; Jung, Seung Eun; Park, Sung Jong

2011-01-01

316

Comparison of effects of transcranial magnetic stimulation on primary motor cortex and supplementary motor area in motor skill learning (randomized, cross over study)  

PubMed Central

Motor skills require quick visuomotor reaction time, fast movement time, and accurate performance. Primary motor cortex (M1) and supplementary motor area (SMA) are closely related in learning motor skills. Also, it is well known that high frequency repeated transcranial magnetic stimulation (rTMS) on these sites has a facilitating effect. The aim of this study was to compare the effects of high frequency rTMS activation of these two brain sites on learning of motor skills. Twenty three normal volunteers participated. Subjects were randomly stimulated on either brain area, SMA or M1. The motor task required the learning of sequential finger movements, explicitly or implicitly. It consisted of pressing the keyboard sequentially with their right hand on seeing 7 digits on the monitor explicitly, and then tapping the 7 digits by memorization, implicitly. Subjects were instructed to hit the keyboard as fast and accurately as possible. Using Musical Instrument Digital Interface (MIDI), the keyboard pressing task was measured before and after high frequency rTMS for motor performance, which was measured by response time (RT), movement time, and accuracy (AC). A week later, the same task was repeated by cross-over study design. At this time, rTMS was applied on the other brain area. Two-way ANOVA was used to assess the carry over time effect and stimulation sites (M1 and SMA), as factors. Results indicated that no carry-over effect was observed. The AC and RT were not different between the two stimulating sites (M1 and SMA). But movement time was significantly decreased after rTMS on both SMA and M1. The amount of shortened movement time after rTMS on SMA was significantly increased as compared to the movement time after rTMS on M1 (p < 0.05), especially for implicit learning of motor tasks. The coefficient of variation was lower in implicit trial than in explicit trial. In conclusion, this finding indicated an important role of SMA compared to M1, in implicit motor learning. PMID:25477809

Kim, Yong Kyun; Shin, Sung Hun

2014-01-01

317

The restoration after repetitive transcranial magnetic stimulation treatment on cognitive ability of vascular dementia rats and its impacts on synaptic plasticity in hippocampal CA1 area.  

PubMed

The purposes of this research were to study the restoration on the cognitive ability of rat models with vascular dementia (VaD) by repetitive transcranial magnetic stimulation (rTMS) treatment and its impacts on synaptic plasticity in hippocampal CA1 area and to further explore the molecular mechanisms of the rTMS treatment on vascular dementia. Thirty-six male Wistar rats were randomly divided into four groups: the normal control group, the vascular dementia model group, the low-frequency rTMS group, and the high-frequency rTMS group. Two-vessel occlusion was employed to make VaD models. Low-frequency rTMS group rats were treated with 0.5 Hz rTMS for 6 weeks. High-frequency rTMS group rats underwent 5 Hz rTMS for 6 weeks. Morris water maze was carried out to detect the ability of spatial learning and memory of rats. The ultra-structural changes of synapses in four groups were observed by transmission electron microscope. Then the expressions of brain-derived neurotrophic factor (BDNF), NMDAR1, and Synaptophysin (SYN) mRNA and proteins in hippocampal CA1 area were determined by real-time PCR, western blot, and immunohistochemistry assay. After rTMS treatment, the learning and memory abilities of VaD rats improved significantly. The ultra-structures of synapses in hippocampal CA1 area in rTMS groups were reformed. The mRNA and protein expressions of BDNF, NMDAR1, and SYN in the low-frequency rTMS group and in the high-frequency rTMS group were higher than that in VaD model group (P < 0.05). rTMS plays an important and beneficial role in the restoration treatment of vascular dementia, which may be related to the mechanism that rTMS can increase the mRNA and protein expressions of BDNF, NMDAR1, and SYN and affect the synaptic plasticity in hippocampal CA1 area. PMID:19953343

Wang, Fei; Geng, Xin; Tao, Hua-Ying; Cheng, Yan

2010-05-01

318

Repetitive transcranial magnetic stimulation as an augmentative strategy for treatment-resistant depression, a meta-analysis of randomized, double-blind and sham-controlled study.  

PubMed

BackgroundDozens of randomized controlled trials (RCTs) and meta-analyses have demonstrated the efficacy of repetitive transcranial magnetic stimulation (rTMS) for major depressive disorder (MDD) treatment, but there has not been a meta-analysis report which evaluates the efficacy and tolerability of rTMS used as an augmentative strategy for antidepressants in treatment-resistant depression (TRD) treatment. We thus conducted this meta-analysis, aimed at clarifying whether rTMS enhances the efficacy of TRD.MethodsWe searched MEDLINE and Cochrane Central Register of Controlled Trials for RCTs for studying the efficacy of rTMS versus (vs) sham condition when combined with antidepressants in TRD treatment, and screened the references of the previous meta-analysis about the rTMS for MDD treatment. Response rates and NNT were chose as the primary outcomes, and remission rates, change from baseline of HAMD scores, dropouts were used as secondary outcomes. For dichotomous data, an intention-to-treat analysis principle was applied; for continuous data, we calculated the standard mean difference between groups with a random-effect model. Sensitivity analysis was done to explore the source of heterogeneity and the factors which potentially impact the efficacy.ResultsSeven RCTs were finally included in the meta-analysis. The total sample size was 279, with 171 in the rTMS group and 108 in the sham group. The pooled response and remission rate for the rTMS and sham group was 46.6% and 22.1%, respectively; the pooled odds ratio (OR) was 5.12 [95% confidence interval (CI) 2.11-12.45, z¿=¿3.60, p¿=¿0.0003, and the associated number needed to treat (NNT) was 3.4. rTMS group achieved a significant reduction of HAMD score than the sham group, the pooled SMD of change from baseline was 0.86 [95% confidence interval (CI) 0.57-1.15, z¿=¿5.75, p¿<¿0.00001]. Because of the small number of included RCTs, the preplanned sensitivity and subgroup analyses were finally abandoned. The dropouts in both groups were relatively low, indicating the high acceptability of rTMS.ConclusionsFor TRD patients, augmentative rTMS after the failure of medications significantly increases the effect of antidepressants, and rTMS was a safe strategy with relatively low adverse events and low dropout rate, suggesting that augmentative rTMS is an effective intervention for TRD. PMID:25433539

Liu, Bangshan; Zhang, Yan; Zhang, Li; Li, Lingjiang

2014-11-30

319

Improvement of health-related quality of life in depression after transcranial magnetic stimulation in a naturalistic trial is associated with decreased perfusion in precuneus  

PubMed Central

Background Assessing Health-related Quality of life (HRQoL) is necessary to evaluate care and treatments provided to patients with major depressive disorder (MDD), in addition to the traditional assessment of clinical outcomes. However, HRQoL remains under-utilized to assess the effectiveness of repetitive transcranial magnetic stimulation (rTMS) in research or in a routine clinical setting. The primary objective of this exploratory study on MDD was to investigate the impact of low-frequency rTMS on HRQoL using the SF-36 questionnaire. A secondary objective was to study the functional neural substrate underlying HRQoL changes using neuroimaging. Methods Fifteen right-handed patients who met DSM-IV criteria for MDD participated in the study. HRQoL was assessed using the SF-36, and regional cerebral blood (rCBF) flow using 99mTc-ECD-SPECT. Voxel based correlation was searched between concomitant changes in rCBF and in HRQoL after rTMS. Results Role-Physical Problems dimension showed a statistical significant improvement of 73.2% (p?=?0.001) and an effect size (Cohen’s d) of 0.43, indicating moderate effect. Five SF-36 dimension scores and the two composite scores showed effect sizes ranged from 0.28 to 0.43. Improvement of Mental Composite Score (MCS)-SF-36 after rTMS was correlated with a concomitant decrease of precuneus perfusion (p?

2012-01-01

320

Noninvasive Transcranial Brain Stimulation and Pain  

PubMed Central

Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are two noninvasive brain stimulation techniques that can modulate activity in specific regions of the cortex. At this point, their use in brain stimulation is primarily investigational; however, there is clear evidence that these tools can reduce pain and modify neurophysiologic correlates of the pain experience. TMS has also been used to predict response to surgically implanted stimulation for the treatment of chronic pain. Furthermore, TMS and tDCS can be applied with other techniques, such as event-related potentials and pharmacologic manipulation, to illuminate the underlying physiologic mechanisms of normal and pathological pain. This review presents a description and overview of the uses of two major brain stimulation techniques and a listing of useful references for further study. PMID:19126365

Rosen, Allyson C.; Ramkumar, Mukund; Nguyen, Tam; Hoeft, Fumiko

2009-01-01

321

Transcranial focused ultrasound as a possible treatment for major depression.  

PubMed

Antidepressants are currently used as initial therapies for major depressive disorder (MDD). However, despite the remarkable increase in medications validated as effective in MDD, treatments are still plagued by inadequate responses in part of MDD patients. For MDD with inadequate responses to medications, brain stimulation methods such as electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS) have been used as alternative strategies for treatment of depression, although each of these modalities has an indication for MDD treatment resistance and suffers from a limitation or weakness. Thus, development of new strategies based on novel theories of MDD may help to develop faster and more effective treatments for MDD. Recent studies have suggested that decreased brain brain-derived neurotrophic factor (BDNF) may be involved in the pathogenesis of MDD. Moreover, increasing brain BDNF and adult hippocampal neurogenesis have been implicated in some of the therapeutic mechanisms of antidepressants. Transcranial focused ultrasound (tFUS), a novel technique to deliver highly focused acoustic energy to a small brain region, has been used for targeted drug delivery by increasing blood-brain barrier permeability, and it can noninvasively focally modulate human cortical function. Recent animal studies have demonstrated that tFUS stimulation can increase BDNF and neurogenesis in mice. Furthermore, the increase blood-brain barrier (BBB) permeability may increase delivery of serum BDNF to the brain. From the above evidence, tFUS can increase brain BDNF levels and neurogenesis in the hippocampus, suggesting it could be an alternative strategy for the treatment of MDD. Further investigations into the frequency and duration of tFUS stimulation are needed to verify the efficacy of this intervention in depressive disorders. PMID:25665863

Tsai, Shih-Jen

2015-04-01

322

Transcranial direct current stimulation (tDCS) produces localized and specific alterations in neurochemistry: A 1H magnetic resonance spectroscopy study  

Microsoft Academic Search

Transcranial direct current stimulation (tDCS) has been found to produce significant changes in behavior, including a large increase of learning and performance for a difficult visual perceptual task (Clark et al., NeuroImage 2010). The mechanisms by which tDCS produces these behavioral effects are currently uncertain. One hypothesis is that anodal tDCS leads to increased metabolic activity in the brain, which

Vincent P. Clark; Brian A. Coffman; Michael C. Trumbo; Charles Gasparovic

2011-01-01

323

Language Lateralization in Children Using Functional Transcranial Doppler Sonography  

ERIC Educational Resources Information Center

Aim: Language lateralization with functional transcranial Doppler sonography (fTCD) and lexical word generation has been shown to have high concordance with the Wada test and functional magnetic resonance imaging in adults. We evaluated a nonlexical paradigm to determine language dominance in children. Method: In 23 right-handed children (12…

Haag, Anja; Moeller, Nicola; Knake, Susanne; Hermsen, Anke; Oertel, Wolfgang H.; Rosenow, Felix; Hamer, Hajo M.

2010-01-01

324

Transcranial direct current stimulation applied over the somatosensory cortex – Differential effect on low and high frequency SEPs  

Microsoft Academic Search

ObjectiveTranscranial direct current stimulation (tDCS) has an influence on the excitability of the human motor cortex measured by motor evoked potentials (MEPs) after transcranial magnetic stimulation. Low and high frequency (HFOs) components of somatosensory evoked potentials (SEPs) were studied questioning whether a comparable effect can be observed after applying tDCS to the human somatosensory cortex.

Anne Dieckhöfer; Till Dino Waberski; Michael Nitsche; Walter Paulus; Helmut Buchner; René Gobbelé

2006-01-01

325

Premotor transcranial direct current stimulation (tDCS) affects primary motor excitability in humans  

Microsoft Academic Search

Recent studies have shown that repetitive transcranial magnetic stimulation (rTMS) over the premotor cortex (PM) modifies the excitability of the ipsilateral primary motor cortex (M1). Transcranial direct current stimulation (tDCS) is a new method to induce neuroplasticity in humans non-invasively. tDCS generates neuroplasticity directly in the cortical area under the electrode, but might also induce effects in distant brain areas,

Klára Boros; Csaba Poreisz; Alexander Münchau; Walter Paulus; Michael A. Nitsche

2008-01-01

326

Short and long-lasting tinnitus relief induced by transcranial direct current stimulation  

Microsoft Academic Search

A significant proportion of the population suffers from tinnitus, a bothersome auditory phantom perception that can severely\\u000a alter the quality of life. Numerous experimental studies suggests that a maladaptive plasticity of the auditory and limbic\\u000a cortical areas may underlie tinnitus. Accordingly, repetitive transcranial magnetic stimulation (rTMS) has been repeatedly\\u000a used with success to reduce tinnitus intensity. The potential of transcranial

Pierre GarinChantal; Chantal Gilain; Jean-Philippe Van Damme; Katalin de Fays; Jacques Jamart; Michel Ossemann; Yves Vandermeeren

327

Estimation of the Iron Loss in Deep-Sea Permanent Magnet Motors considering Seawater Compressive Stress  

PubMed Central

Deep-sea permanent magnet motor equipped with fluid compensated pressure-tolerant system is compressed by the high pressure fluid both outside and inside. The induced stress distribution in stator core is significantly different from that in land type motor. Its effect on the magnetic properties of stator core is important for deep-sea motor designers but seldom reported. In this paper, the stress distribution in stator core, regarding the seawater compressive stress, is calculated by 2D finite element method (FEM). The effect of compressive stress on magnetic properties of electrical steel sheet, that is, permeability, BH curves, and BW curves, is also measured. Then, based on the measured magnetic properties and calculated stress distribution, the stator iron loss is estimated by stress-electromagnetics-coupling FEM. At last the estimation is verified by experiment. Both the calculated and measured results show that stator iron loss increases obviously with the seawater compressive stress. PMID:25177717

Wei, Yanyu; Zou, Jibin; Li, Jianjun; Qi, Wenjuan; Li, Yong

2014-01-01

328

Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349  

NASA Astrophysics Data System (ADS)

analyses of deep tow magnetic anomalies and International Ocean Discovery Program Expedition 349 cores show that initial seafloor spreading started around 33 Ma in the northeastern South China Sea (SCS), but varied slightly by 1-2 Myr along the northern continent-ocean boundary (COB). A southward ridge jump of ˜20 km occurred around 23.6 Ma in the East Subbasin; this timing also slightly varied along the ridge and was coeval to the onset of seafloor spreading in the Southwest Subbasin, which propagated for about 400 km southwestward from ˜23.6 to ˜21.5 Ma. The terminal age of seafloor spreading is ˜15 Ma in the East Subbasin and ˜16 Ma in the Southwest Subbasin. The full spreading rate in the East Subbasin varied largely from ˜20 to ˜80 km/Myr, but mostly decreased with time except for the period between ˜26.0 Ma and the ridge jump (˜23.6 Ma), within which the rate was the fastest at ˜70 km/Myr on average. The spreading rates are not correlated, in most cases, to magnetic anomaly amplitudes that reflect basement magnetization contrasts. Shipboard magnetic measurements reveal at least one magnetic reversal in the top 100 m of basaltic layers, in addition to large vertical intensity variations. These complexities are caused by late-stage lava flows that are magnetized in a different polarity from the primary basaltic layer emplaced during the main phase of crustal accretion. Deep tow magnetic modeling also reveals this smearing in basement magnetizations by incorporating a contamination coefficient of 0.5, which partly alleviates the problem of assuming a magnetic blocking model of constant thickness and uniform magnetization. The primary contribution to magnetic anomalies of the SCS is not in the top 100 m of the igneous basement.

Li, Chun-Feng; Xu, Xing; Lin, Jian; Sun, Zhen; Zhu, Jian; Yao, Yongjian; Zhao, Xixi; Liu, Qingsong; Kulhanek, Denise K.; Wang, Jian; Song, Taoran; Zhao, Junfeng; Qiu, Ning; Guan, Yongxian; Zhou, Zhiyuan; Williams, Trevor; Bao, Rui; Briais, Anne; Brown, Elizabeth A.; Chen, Yifeng; Clift, Peter D.; Colwell, Frederick S.; Dadd, Kelsie A.; Ding, Weiwei; Almeida, Iván. Hernández; Huang, Xiao-Long; Hyun, Sangmin; Jiang, Tao; Koppers, Anthony A. P.; Li, Qianyu; Liu, Chuanlian; Liu, Zhifei; Nagai, Renata H.; Peleo-Alampay, Alyssa; Su, Xin; Tejada, Maria Luisa G.; Trinh, Hai Son; Yeh, Yi-Ching; Zhang, Chuanlun; Zhang, Fan; Zhang, Guo-Liang

2014-12-01

329

Gravity and magnetic anomalies and the deep structure of the Parnaiba cratonic basin, Brazil  

E-print Network

Gravity and magnetic anomalies and the deep structure of the Parnaiba cratonic basin, Brazil A. B profile across the Parnaiba cratonic basin in NorthEast Brazil. The purpose of this project is to acquire margin of Parnaíba Basin, Brazil. Geophysics 64: 337-356. Ussami N, Cogo de Sa N, Molina EC. 1993

Watts, A. B. "Tony"

330

Deep superconducting magnetic traps for neutral atoms and molecules  

NASA Astrophysics Data System (ADS)

We describe the design, construction and performance of three realizations of a high-field superconducting magnetic trap for neutral atoms and molecules. Each of these traps utilizes a pair of coaxial coils in the anti-Helmholtz geometry and achieves depths greater than 4 T, allowing it to capture magnetic atoms and molecules cooled in a cryogenic buffer gas. Achieving this depth requires that the repulsive force between the coils (which can exceed 30 metric tons) be contained. We also describe additional features of the traps, including the elimination of trapped fluxes from the coils and the integration of the coils into a cryogenic vacuum environment suitable for producing cold atoms and molecules.

Harris, J. G. E.; Michniak, R. A.; Nguyen, S. V.; Campbell, W. C.; Egorov, D.; Maxwell, S. E.; van Buuren, L. D.; Doyle, J. M.

2004-01-01

331

Changes of symptom and EEG in mal de debarquement syndrome patients after repetitive transcranial magnetic stimulation over bilateral prefrontal cortex: a pilot study.  

PubMed

Mal de debarquement syndrome (MdDS) is a chronic disorder of imbalance characterized by a feeling of rocking and swaying. The medical treatment for MdDS is still limited. Motivated by our previous pilot study that demonstrates the promising clinical efficacy of repetitive transcranial stimulation (rTMS) in MdDS patients, a novel rTMS paradigm, i.e., 1 Hz stimulation over ipsilateral dorsal lateral prefrontal cortex (DLPFC) with respect to the dominant hand followed by 10 Hz stimulation over contralateral DLPFC, was proposed and conducted in MdDS in the present study. To evaluate the potential efficacy, we examined the changes before and after rTMS in both subjective reported symptom using visual analogue scale (VAS) and direct brain activity in resting state electroencephalography (rsEEG). To disentangle activity from distinct brain substrates and/or local networks in rsEEG signals, a group-wise independent component analysis was employed and the corresponding spectral power changes were examined in the identified components. In general, reduction in rocking sensation was reported in five of ten subjects (with dramatic reductions (changes > 30) in three subjects) after rTMS using the present paradigm, while no changes and slight increases in rocking sensation were reported in the remaining subjects. In rsEEG, significant elevated spectral powers in low frequency bands (i.e., theta and alpha) over broad areas of occipital, parietal, motor, and prefrontal cortices were induced by rTMS, reflecting the enhancement of cortical inhibition over these areas. Meanwhile, the significant correlations between changes in rsEEG and VAS scores were detected in the high frequency bands (i.e., high alpha and beta) over posterior parietal and left visual areas, reflecting the suppression of spatial information processing. Therefore, the present findings demonstrate the promising clinical efficacy of a new rTMS paradigm for MdDS, and suggest its merit for further studies in more patients. PMID:25570942

Guofa Shou; Han Yuan; Urbano, Diamond; Yoon-Hee Cha; Lei Ding

2014-01-01

332

RESEARCH Open Access Facilitating myoelectric-control with transcranial  

E-print Network

RESEARCH Open Access Facilitating myoelectric-control with transcranial direct current stimulation treatment at the central nervous system (CNS) level with transcranial direct current stimulation (t interfaces. Keywords: Functional electrical stimulation, Myoelectric control, Transcranial direct current

Paris-Sud XI, Université de

333

Repetitive Transcranial Magnetic Stimulation Over the Dorsolateral Prefrontal Cortex for Treating Posttraumatic Stress Disorder: An Exploratory Meta-Analysis of Randomized, Double-Blind and Sham-Controlled Trials  

PubMed Central

Objective Repetitive transcranial magnetic stimulation (rTMS) applied to the dorsolateral prefrontal cortex (DLPFC) has yielded promising results as a treatment for posttraumatic stress disorder (PTSD). However, to date, no quantitative review of its clinical utility has been published. Method: We searched for randomized and sham-controlled trials from 1995 to March 2013 using MEDLINE, Embase, PsycINFO, CENTRAL, and SCOPUS. We then performed an exploratory random effects meta-analysis. Results: Studies on rTMS applied to the right DLPFC included 64 adults with PTSD. The pooled Hedges g effect size for pre and post changes in clinician-rated and self-reported PTSD symptoms were, respectively, 1.65 (P < 0.001) and 1.91 (P < 0.001), indicating significant and large-sized differences in outcome favouring active rTMS. Also, there were significant pre and post decreases with active rTMS in overall anxiety (Hedges g = 1.24; P = 0.02) and depressive (Hedges g = 0.85; P < 0.001) symptoms. Dropout rates at study end did not differ between active and sham rTMS groups. Regarding rTMS applied to the left DLPFC, there is only one study published to date (using a high frequency protocol), and its results showed that active rTMS seems to be superior overall to sham rTMS. Conclusions: Our exploratory meta-analysis shows that active rTMS applied to the DLPFC seems to be effective and acceptable for treating PTSD. However, the small number of subjects included in the analyses limits the generalizability of these findings. Future studies should include larger samples and deliver optimized stimulation parameters. PMID:25565694

Berlim, Marcelo T; Van den Eynde, Frederique

2014-01-01

334

Repetitive transcranial magnetic stimulation (rTMS) augmentation of selective serotonin reuptake inhibitors (SSRIs) for SSRI-resistant obsessive-compulsive disorder (OCD): a meta-analysis of randomized controlled trials  

PubMed Central

Background and objective: Randomized controlled trials (RCTs) on repetitive transcranial magnetic stimulation (rTMS) as augmentation of selective serotonin reuptake inhibitors (SSRIs) for SSRI-resistant obsessive-compulsive disorder (OCD) have yielded conflicting results. Therefore, this meta-analysis was conducted to assess the efficacy of this strategy for SSRI-resistant OCD. Methods: Scientific and medical databases, including international databases (PubMed, MEDLINE, EMBASE, CCTR, Web of Science, PsycINFO), two Chinese databases (CBM-disc, CNKI), and relevant websites dated up to July 2014, were searched for RCTs on this strategy for treating OCD. Mantel-Haenszel random-effects model was used. Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score, response rates and drop-out rates were evaluated. Results: Data were obtained from nine RCTs consisting of 290 subjects. Active rTMS was an effective augmentation strategy in treating SSRI-resistant OCD with a pooled WMD of 3.89 (95% CI = [1.27, 6.50]) for reducing Y-BOCS score and a pooled odds ratio (OR) of 2.65 (95% CI = [1.36, 5.17] for response rates. No significant differences in drop-out rates were found. No publication bias was detected. Conclusion: The pooled examination demonstrated that this strategy seems to be efficacious and acceptable for treating SSRI-resistant OCD. As the number of RCTs included here was limited, further large-scale multi-center RCTs are required to validate our conclusions. PMID:25663986

Ma, Zhong-Rui; Shi, Li-Jun

2014-01-01

335

Paired-pulse transcranial magnetic stimulation reveals probability-dependent changes in functional connectivity between right inferior frontal cortex and primary motor cortex during go/no-go performance  

PubMed Central

The functional role of the right inferior frontal cortex (rIFC) in mediating human behavior is the subject of ongoing debate. Activation of the rIFC has been associated with both response inhibition and with signaling action adaptation demands resulting from unpredicted events. The goal of this study is to investigate the role of rIFC by combining a go/no-go paradigm with paired-pulse transcranial magnetic stimulation (ppTMS) over rIFC and the primary motor cortex (M1) to probe the functional connectivity between these brain areas. Participants performed a go/no-go task with 20% or 80% of the trials requiring response inhibition (no-go trials) in a classic and a reversed version of the task, respectively. Responses were slower to infrequent compared to frequent go trials, while commission errors were more prevalent to infrequent compared to frequent no-go trials. We hypothesized that if rIFC is involved primarily in response inhibition, then rIFC should exert an inhibitory influence over M1 on no-go (inhibition) trials regardless of no-go probability. If, by contrast, rIFC has a role on unexpected trials other than just response inhibition then rIFC should influence M1 on infrequent trials regardless of response demands. We observed that rIFC suppressed M1 excitability during frequent no-go trials, but not during infrequent no-go trials, suggesting that the role of rIFC in response inhibition is context dependent rather than generic. Importantly, rIFC was found to facilitate M1 excitability on all low frequent trials, irrespective of whether the infrequent event involved response inhibition, a finding more in line with a predictive coding framework of cognitive control. PMID:24282398

van Campen, A. Dilene; Neubert, Franz-Xaver; van den Wildenberg, Wery P. M.; Ridderinkhof, K. Richard; Mars, Rogier B.

2013-01-01

336

Chronic high-frequency repetitive transcranial magnetic stimulation improves age-related cognitive impairment in parallel with alterations in neuronal excitability and the voltage-dependent Ca(2+) current in female mice.  

PubMed

Chronic high-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method to increase the excitability of neurons, and it induces long-term effects that can improve symptoms related to neurodegenerative diseases, including cognitive ability. The present study was undertaken to identify the mechanism by which rTMS improves cognitive impairments in mice. The novel object recognition test in vivo was used to evaluate the cognitive function of the mice. Whole-cell patch-clamp recordings were used to evaluate the neuronal excitability, including the resting membrane potential, the number of action potentials induced by depolarized current, after-hyperpolarization, and the voltage-dependent Ca(2+) current in hippocampal slices. We found that the aged mice showed impairments in cognitive function, and high-frequency (25Hz) rTMS for 14 consecutive-days ameliorated the impairments. Whole-cell patch-clamp recordings showed that, compared to matured mice, the hippocampal CA1 pyramidal neurons of aged mice showed significantly hyperpolarized resting membrane potential, significantly decreased numbers of action potentials after injection of depolarizing current, and significantly increased after-hyperpolarization after an action potential. The exposure to high-frequency rTMS significantly improved the above deficits in the neuronal excitability in the aged rTMS mice. Consistent with the above changes, the exposure to high-frequency rTMS also significantly decreased the voltage-dependent Ca(2+) current of the neurons compared with the aged sham mice. These data suggested that the rTMS could improve the age-related cognitive impairment in parallel with regulating the neuronal excitability and modifying the voltage-dependent Ca(2+) channels. PMID:25451310

Wang, Hua-Long; Xian, Xiao-Hui; Wang, Yan-Yong; Geng, Yuan; Han, Bing; Wang, Ming-Wei; Li, Wen-Bin

2015-02-01

337

Advances in transcranial doppler ultrasonography  

Microsoft Academic Search

Transcranial Doppler ultrasonography (TCD) is the only noninvasive real-time neuroimaging modality for the evaluation of characteristics\\u000a of blood flow in basal intracerebral vessels that adds physiologic information to structural imaging. TCD has been rapidly\\u000a evolving from a simple noninvasive diagnostic tool to an imaging modality with a broad spectrum of clinical applications.\\u000a In acute stroke, TCD can provide rapid information

Georgios Tsivgoulis; Andrei V. Alexandrov; Michael A. Sloan

2009-01-01

338

Synthesis of brightly PEGylated luminescent magnetic upconversion nanophosphors for deep tissue and dual MRI imaging  

PubMed Central

We developed a novel method to fabricate monodispersed biocompatible Yb/Er or Yb/Tm doped ?-NaGdF4 upconversion phosphors using polyelectrolytes to prevent irreversible particle aggregation during the conversion of the precursor (Gd2O(CO3)2•H2O:Yb/Er or Yb/Tm) to ?-NaGdF4:Yb/Er or Yb/Tm. The polyelectrolyte on the outer surface of nanophosphors also provided an amine tag for PEGylation. This method is also employed to fabricate PEGylated magnetic upconversion phosphors with Fe3O4 as the core and ?-NaGdF4 as a shell. These magnetic upconversion nanophosphors have relatively high saturation magnetization (7.0 emu g-1) and magnetic susceptibility (1.7×10-2 emu g-1 Oe-1), providing them with large magnetophoretic mobilities. We have studied their magnetic properties for separation and controlled release in flow, their optical properties for cell labeling, deep tissue imaging, and their T1 and T2-weighted magnetic resonance imaging (MRI) relaxivities. The magnetic upconversion phosphors display both strong magnetophoresis, dual MRI imaging (r1=2.9 mM-1 s-1, r2=204 mM-1 s-1), and bright luminescence under 1 cm chicken breast. PMID:23828629

Chen, Hongyu; Qi, Bin; Moore, Thomas; Colvin, Daniel C.; Crawford, Thomas; Gore, John C.; Alexis, Frank; Mefford, O. Thompson; Anker, Jeffrey N.

2014-01-01

339

Combined Transnasal and Transcranial Removal of a Giant Clival Chordoma  

PubMed Central

Clival chordomas confront the surgeon with the task of resecting an aggressively invasive and destructive tumor in a critical surrounding. For many, mainly smaller, chordomas, the transnasal transclival approach is a feasible and safe surgical access. Larger tumors and especially those with extensive intradural, retrochiasmal, and/or deep cervical expansion are mostly approached by open craniotomy. Staged procedures are also commonly used in the case of expansive tumor growth. We present the first case of a single-session combined transnasal and transcranial approach to radically resect a large clival chordoma. PMID:25083400

Koechlin, Nicolas O.; Simmen, Daniel; Briner, Hans Rudolf; Reisch, Robert

2014-01-01

340

Widespread Magnetofossil Occurrences in Deep-sea Sediments and Implications for Paleo- and Environmental Magnetism (Invited)  

NASA Astrophysics Data System (ADS)

Recent progress in rock magnetism has enabled quantitative estimation of magnetizations carried by magnetofossils. Using FORC diagrams, IRM component analyses, ferromagnetic resonance spectroscopy, low-temperature magnetometry, and transmission electron microscopy, it has been found that magnetofossils are widespread in deep-sea sediments and are often a dominant constituent of magnetic mineral assemblages. Some studies have documented a relationship between increased magnetofossil abundances and enhanced oceanic productivity induced by iron fertilization via eolian dust. The morphology of magnetosomes, which is species specific, may reflect a preference of magnetotactic bacteria for particular redox conditions. Dominant magnetofossil morphologies in sediments (cubo-octahedral vs. elongated) can be detected with rock magnetic techniques. Thus, magnetofossil abundance and morphology have considerable potential as paleoenvironmental indicators. It is widely held that magnetotactic bacteria live at or below the oxic-anoxic transition zone (OATZ) in chemically stratified aquatic environments. If so, it is expected that sediments that contain magnetofossils would have acquired their remanent magnetization at around the OATZ, and that the magnetization carried by magnetofossils will be delayed with respect to a pDRM carried by detrital magnetic minerals if the OATZ lies below the surface mixed layer and the pDRM acquisition zone. However, magnetofossils often dominate the magnetic mineral assemblage even in marine red clays that lack an OATZ. Changes in the relative abundance of biogenic and detrital magnetic components can be estimated from the ratio of ARM susceptibility to SIRM; a smaller average magnetic grain size and weaker magnetostatic interactions in the biogenic component causes higher ARM susceptibility. In relative paleointensity estimations, the kARM/SIRM ratio sometimes anti-correlates with normalized intensity regardless of the choice of normalizer (ARM or IRM). This implies that changes in relative abundance of biogenic magnetite may not be well compensated for by the widely used normalizers and may contaminate relative paleointensity records.

Yamazaki, T.; Roberts, A. P.

2013-12-01

341

Magnetic properties of Archean gneisses from the northeastern North China Craton: the relationship between magnetism and metamorphic grade in the deep continental crust  

NASA Astrophysics Data System (ADS)

Magnetic mineralogy of crustal rocks has important implications for understanding continental crustal evolution and origin of regional magnetic anomalies. However, magnetic properties of the deep continental crust are still poorly understood. In this paper, measurements of density (?), mass-specific magnetic susceptibility (?), natural remanent magnetization (NRM) and magnetic hysteresis loops, temperature-dependent magnetic susceptibility (?-T), chemical and mineral analyses were conducted on Archean gneiss samples from the Jixian petrophysical section in the Precambrian terrain, northeastern North China Craton, with the aim of refining understanding of magnetic phase transformations in the deep crustal rocks. Results show that density and rock magnetic properties change distinctly with metamorphic facies. The dominant magnetic mineral is magnetite, while a little hematite is present in a few samples. Together with geochemical and mineralogical compositions, it is inferred that progressive increase in metamorphic grade from east to west is the major cause for magnetic enhancement of the lower crust in the studied section. Therefore, we conclude that study of magnetic phases of deep crustal rocks can offer important insights into the history of high metamorphic grade terranes.

Wang, Hongcai; Liu, Qingsheng; Zhao, Weihua; Li, Zhiyong; Zheng, Jianping

2015-04-01

342

Short and long duration transcranial direct current stimulation (tDCS) over the human hand motor area  

Microsoft Academic Search

The aim of the present paper is to study effects of short and long duration transcranial direct current stimulation (tDCS)\\u000a on the human motor cortex. In eight normal volunteers, motor evoked potentials (MEPs) induced by transcranial magnetic stimulation\\u000a (TMS) were recorded from the right first dorsal interosseous muscle, and tDCS was given with electrodes over the left primary\\u000a motor cortex

Toshiaki Furubayashi; Yasuo Terao; Noritoshi Arai; Shingo Okabe; Hitoshi Mochizuki; Ritsuko Hanajima; Masashi Hamada; Akihiro Yugeta; Satomi Inomata-Terada; Yoshikazu Ugawa

2008-01-01

343

Diminution of training-induced transient motor cortex plasticity by weak transcranial direct current stimulation in the human  

Microsoft Academic Search

Training of a thumb movement in the opposite direction of a twitch in response to transcranial magnetic stimulation (TMS) induces a transient directional change of post-training TMS-evoked movements towards the trained direction. Functional synaptic mechanisms seem to underlie this rapid training-induced plasticity. Transcranial direct current stimulation (tDCS) induces outlasting changes of cerebral excitability, thus presenting as promising tool for neuroplasticity

Karin Rosenkranz; Michael A Nitsche; Frithjof Tergau; Walter Paulus

2000-01-01

344

Cathodal transcranial direct current stimulation of the right Wernicke’s area improves comprehension in subacute stroke patients  

Microsoft Academic Search

Previous studies have shown the appearance of right-sided language-related brain activity in right-handed patients after a stroke. Non-invasive brain stimulation such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) have been shown to modulate excitability in the brain. Moreover, rTMS and tDCS have been found to improve naming in non-fluent post-stroke aphasic patients. Here, we investigated

Dae Sang You; Dae-Yul Kim; Min Ho Chun; Seung Eun Jung; Sung Jong Park

2011-01-01

345

Insights into motor performance and muscle fatigue based on transcranial stimulation of the human motor cortex.  

PubMed

1. Direct cortical stimulation of motor and sensory areas of the cortex in experimental animals and some neurosurgical patients has provided much useful physiological information. Some of the benefits of this approach can be provided in awake volunteer subjects using new techniques which activate the motor cortex thorough the skull (i.e. transcranial electrical or magnetic stimulation). 2. Both electrical and magnetic transcranial stimulation produce complex descending corticospinal volleys which usually contain a direct component (via corticofugal axons) and an indirect trans-synaptic component. Changes in cortical 'excitability' can affect the evoked corticofugal volleys and the electromyographic responses which they involve. 3. Apart from its diagnostic applications to patients with neurological disorders, transcranial stimulation has been applied to the study of a range of aspects of human motor control ranging from apparent cortical 'plasticity' to the changes in cortical behaviour produced by exercise. PMID:8911740

Gandevia, S C

1996-01-01

346

Deep structure of the Mount Amram igneous complex, interpretation of magnetic and gravity data  

NASA Astrophysics Data System (ADS)

The Mt Amram igneous complex (AIC) represents northern tip of the Neoproterozoic Arabian Nubian Shield (ANS). For the first time the AIC deep structure was studied using the gravity, aero and ground magnetic, magnetic susceptibility and density measurements and geological data. Analysing all available data at the Amram area we concluded what only monzonite body can be reason for gravity high and coinciding reduced to pole (RTP) maximum. Geological knowledge allowed suggesting its intrusive character and compact body form. Cluster of inverse solutions (Werner deconvolution) localized this body as initial model for forward modelling. Further iterations (23/4-D forward modelling) clarified the monzonite geometry and properties; the modelling allowed also to investigate the non-uniqueness and estimate also the confident intervals for final solution. The research consists three interconnected stages. At the detailed scale, ground magnetic data suggested three magmatic blocks of few hundred meters shifted dextral about 100 m along the Zefunut fault. Estimated accuracy for geometry of the magnetic bodies is a few tens metres. At the middle scale, quantitative gravity and magnetic interpretations provide model of the monzonite body, which is an order of magnitude more than the volume of the felsic rhyolites and granite rocks. Boundary of the whole monzonite body was estimated with accuracy as a hundred meters. As a result we suggest that the parent magma for the AIC is the monzonite, similar to the model suggested for the Timna Igneous Complex 12 km north of the AIC. The model developed can be applied to evaluate the subsurface volumes of the mafic magmatic rocks in adjacent locations. At the regional scale for exposed the Sinai and Arab Saudi Precambrian crystalline shield our approach allows to understand the apparent contradiction between geological predominantly granite composition (low magnetic rocks) and magnetic data. The aeromagnetic data show number strong magnetic anomalies suggesting the presence large volume of high magnetic (mainly basic) rocks at the depth. This problem is proposed for future research.

Shirman, Boris; Rybakov, Michael; Beyth, Michael; Mushkin, Amit; Ginat, Hanan

2015-03-01

347

Repetitive Transcranial Magnetic Stimulation of the Right Dorsolateral Prefrontal Cortex in Posttraumatic Stress Disorder: A Double-Blind, Placebo-Controlled Study  

Microsoft Academic Search

Objective: The efficacy of repetitive tran- scranial magnetic stimulation (rTMS) of the right prefrontal cortex was studied in patients with posttraumatic stress disor- der (PTSD) under double-blind, placebo- controlled conditions. Method: Twenty-four patients with PTSD were randomly assigned to receive rTMS at low frequency (1 Hz) or high frequency (10 Hz) or sham rTMS in a double-blind design. Treatment was

Hagit Cohen; D. Zeev Kaplan; Moshe Kotler; Irena Kouperman; Regina Moisa; Nimrod Grisaru

2004-01-01

348

Development of marine magnetic vector measurement system using AUV and deep-towed vehicle  

NASA Astrophysics Data System (ADS)

Marine magnetic survey is one of useful methods in order to investigate the nature of the oceanic crust. Most of the data are, however, intensity of the geomagnetic field without its direction. Therefore we cannot properly apply a physical formula describing the relation between magnetic field and magnetization to analyses of the data. With this problem, Isezaki (1986) developed a shipboard three-component magnetometer which measures the geomagnetic vector at the sea. On the other hand, geophysical surveys near the seafloor have been more and more necessary in order to show the details of the oceanic crust. For instance, development of seabed resources like hydrothermal deposits needs higher resolution surveys compared with conventional surveys at the sea for accurate estimation of abundance of the resources. From these viewpoints, we have been developing a measurement system of the deep-sea geomagnetic vector using AUV and deep-towed vehicle. The measurement system consists of two 3-axis flux-gate magnetometers, an Overhauser magnetometer, an optical fiber gyro, a main unit (control, communication, recording), and an onboard unit. These devices except for the onboard unit are installed in pressure cases (depth limit: 6000m). Thus this measurement system can measure three components and intensity of the geomagnetic field in the deep-sea. In 2009, the first test of the measurement system was carried out in the Kumano Basin using AUV Urashima and towing vehicle Yokosuka Deep-Tow during the R/V Yokosuka YK09-09 cruise. In this test, we sank a small magnetic target to the seafloor, and examined how the system worked. As a result, we successfully detected magnetic anomaly of the target to confirm the expected performance of that in the sea. In 2010, the measurement system was tested in the Bayonnaise Knoll area both using a titanium towing frame during the R/V Bosei-maru cruise and using AUV Urashima during the R/V Yokosuka YK10-17 cruise. The purpose of these tests was to evaluate the performance of the system in an actual hydrothermal deposit area for practical applications of that. The Bayonnaise Knoll is a submarine caldera with an outer rim of 2.5-3 km and a floor of 840-920 m, which is located in the Izu-Ogasawara arc. A large hydrothermal deposit, Hakurei deposit lies in the southeast part of the caldera. In the R/V Bosei-maru cruise, we observed three components of magnetic anomalies at depths of 400-570 m along SE-NW and WE tracks across the caldera. In the R/V Yokosuka YK10-17 cruise, we observed three components and intensity of magnetic anomalies at altitudes of 60-100 m around the Hakurei deposit and at depth of 500 m above the caldera. From these tests, we have succeeded in measuring the geomagnetic vector and intensity using the AUV and the deep-towed vehicle, and also have obtained detailed magnetic anomaly in the Hakurei deposit area. We will here present the outlines of the measurement system and the tests in the sea. Note that this study has been supported by the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.; Nishimura, K.; Baba, H.

2012-04-01

349

Magnetic Anomalies and Rock Magnetic Properties Related to Deep Crustal Rocks of the Athabasca Granulite Terrane, Northern Canada  

NASA Astrophysics Data System (ADS)

The Athabasca granulite terrane in northernmost Saskatchewan, Canada is an exceptional exposure of lower crustal rocks having experienced several high temperature events (ca 800C) during a prolonged period of deep-crustal residence (ca 1.0 GPa) followed by uplift and exhumation. With little alteration since 1.8 Ga these rocks allow us to study ancient lower crustal lithologies. Aeromagnetic anomalies over this region are distinct and complex, and along with other geophysical measurements, define the Snowbird Tectonic zone, stretching NE-SW across northwestern Canada, separating the Churchill province into the Hearne (mid-crustal rocks, amphibolite facies) from the Rae (lower crust rocks, granulite facies). Distinct magnetic highs and lows appear to relate roughly to specific rock units, and are cut by mapped shear zones. Over fifty samples from this region, collected from the major rock types, mafic granulites, felsic granulites, granites, and dike swarms, as well as from regions of both high and low magnetic anomalies, are being used to investigate magnetic properties. The intention is to investigate what is magnetic in the lower crust and how it produces the anomalies observed from satellite measurements. The samples studied reveal a wide range of magnetic properties with natural remanent magnetization ranging from an isolated high of 38 A/m to lows of 1 mA/m. Susceptibilities also range over several orders of magnitude, from 1 to 1 x10-4 SI. Magnetite is identified in nearly all samples using both low and high temperature measurements, but concentrations are generally very low. Hysteresis properties on 41 samples reveal nearly equal numbers of samples represented by PSD and MD grains, with a few samples (N=6) plotting in or close to the SD region. Low temperature measurements indicate that most samples contain magnetite, showing a marked Verway transition around 120K. Also identified in nearly half of the samples is pyrrhotite, noted by low temperature transitions at 30-35K. Preliminary results indicate that the same general lithologies can have very different magnetic properties with varying concentrations of magnetic minerals and with widely varying domain sizes and thus magnetic behavior. Additional work is needed to fully understand the magnetic signature causing the aeromagnetic anomalies, but with this information we will be able to better understand the varying rock types, compositions, and exposures in lower crustal rocks, be able to predict anomaly patterns, and eventually better understand the geologic history of this complex area.

Brown, L. L.; Williams, M. L.

2010-12-01

350

Deep sea three component magnetic survey using ROV in the hydrothermal vent of the Lau Basin  

NASA Astrophysics Data System (ADS)

We conducted magnetic survey at Apr., 2011 in the western slope of the caldera of TA25, the Lau Basin, the southwestern Pacific using IBRV(Ice Breaker Research Vessel) ARAON of KORDI(Korea Ocean Research and Development Institute), ROV(Remotely Operated Vehicle) of Oceaneering Co. and three component magnetometer(Fig. 1,Fig. 2). The deep-sea three component magnetic survey lines are the 13 N-S lines(100 m spacing) and the 2 E-W lines(Fig. 2). The depth ranges of the survey area are from about 900 m to 1200 m, below sea level. For the magnetic survey, the magnetometer sensor and the data logger was attached with the upper part and lower part of ROV, respectively(Fig. 2). We wanted to make the distance between the magnetometer sensor and ROV over 2 m long to reduce the noise effect of ROV. But, for the safe of deployment and recovery of ROV, the distance between the magnetometer sensor and ROV was 126 cm(Fig. 2). In the magnetic survey, ROV followed the planning tracks at 25~30 m above seafloor using the altimeter and USBL(Ultra Short Base Line) of ROV. IBRV ARAON accompanied ROV on the magnetic survey. The three component magnetometer measure the X(North), Y(East) and Z(Vertical) vector components of a magnetic field. A motion sensor(Oxtans) provided us the data of pitch, roll, yaw for the correction of the magnetic data to the motion of ROV. The data of the magnetometer sensor and the motion sensor were recorded on a notebook through the optical cable of ROV and the network of ARON using magnetometer software. The precision positions of magnetic data were merged by the post-processing of USBL of ROV. Hydrothermal fluids over Curie temperature can quickly alter or replace the iron-rich magnetic minerals, reducing the magnetic remanence of the crustal rocks, in some cases to near 0A/m magnetization. So, the obtained three component magnetic data are fully utilized by finding possible hydrothermal vents of the survey area.

Kim, C.; Park, C.

2011-12-01

351

Search for Magnetic Monopoles with Deep Underwater Cherenkov Detectors at Lake Baikal  

E-print Network

The deep underwater Cherenkov neutrino telescope NT-200 is currently under construction at Lake Baikal. The "subdetectors" NT-36 (1993-95) and NT-72 (1995-96) have been operating successfully over 3 years. Various techniques have been developed to search for magnetic monopoles with these arrays. Here we describe a method used to detect superheavy slowly moving (beta = v/c = 0.00001 - 0.001) monopoles catalyzing baryon decay. We present results obtained from the preliminary analysis of the data taken with NT-36 detector in 1993. Furthermore, possibilities to observe faster (beta = 0.2 - 1) monopoles via other effects are discussed.

The BAIKAL Collaboration

1996-01-30

352

Search for magnetic monopoles with deep underwater Cherenkov detectors at Lake Baikal  

E-print Network

The deep underwater Cherenkov neutrino telescope NT-200 is currently under construction at Lake Baikal. The "subdetectors" NT-36 (1993-95) and NT-72 (1995-96) have been operating successfully over 3 years. Various techniques have been developed to search for magnetic monopoles with these arrays. Here we describe a method used to detect superheavy slowly moving (beta = v/c = 0.00001 - 0.001) monopoles catalyzing baryon decay. We present results obtained from the preliminary analysis of the data taken with NT-36 detector in 1993. Furthermore, possibilities to observe faster (beta = 0.2 - 1) monopoles via other effects are discussed.

Belolaptikov, I A; Borisovets, B A; Budnev, N M; Chensky, A G; Danilchenko, I A; Djilkibaev, J A M; Dobrynin, V I; Domogatsky, G V; Doroshenko, A A; Fialkovsky, S V; Gaponenko, O N; Garus, A A; Gress, O A; Gress, T A; Heukenkamp, H; Karle, A; Klabukov, A M; Klimov, A I; Klimushin, S I; Koshechkin, A P; Kulepov, V F; Kuzmichov, L A; Lubsandorzhiev, B K; Mikolajski, T; Milenin, M B; Mirgazov, R R; Moroz, A V; Moseiko, N I; Nikiforov, S A; Osipova, E A; Panfilov, A I; Parfenov, Yu V; Pavlov, A A; Petukhov, D P

1996-01-01

353

Deep-sea Vector Magnetic Anomalies over the Bayonnaise Knoll Caldera (Izu-Ogasawara Arc) (Invited)  

NASA Astrophysics Data System (ADS)

The Bayonnaise Knoll caldera is located on the eastern margin of the backarc rift zone of the Izu-Ogasawara island arc. The caldera rim is ~3 km in diameter and 100-200 m high from the caldera floor 840-920 m deep. A large active hydrothermal field associated with sulfide deposit, called the Hakurei site, has been found at the foot of the southeastern caldera wall. We conducted deep-sea magnetic measurements using autonomous underwater vehicles to map ~75 % of an area 3 km by 4 km in the caldera. The magnetic vector field data were collected at 40-150 m altitude along the survey lines spaced 80-200 m apart. We improved the conventional correction method applied for removing the effect of vehicle magnetization, which greatly enhanced the precision of the resulting vector anomalies and allowed us to use the vector anomaly instead of the total intensity anomaly for inversion analysis. The magnetization distribution obtained using the vector anomaly was significantly different from the one obtained using the total intensity anomaly, especially in areas where the survey tracks were widely spaced. The aliasing effect appears in areas of sparse data distribution, and the magnetic field is more correctly calculated from the vector anomaly than the total intensity anomaly. The magnetization distribution in the caldera has two major features: a ~1.5-km wide belt of high magnetization, trending NNW-SSE through the caldera, and a clear low magnetization zone, ~300 m x ~500 m wide, extending over the Hakurei site. The high magnetization belt is considered to reflect basaltic volcanism associated with the backarc rifting that occurred after the formation of the Bayonnaise Knoll. The low magnetization zone is interpreted as the alteration zone resulting from the hydrothermal activity. Several zones of localized high magnetization are recognized within the high magnetization belt, some of them in the caldera wall adjacent to the low magnetization zone of the Hakurei site. We speculate that intensive magma intrusion occurred beneath the caldera wall and has provided the heat to generate hydrothermal fluid, which has been spouting out through the caldera wall faults. The surface expression of the vent field extends beyond the alteration zone inferred from the magnetization distribution, spreading upwards in the caldera wall. High-resolution topography around the Hakurei site indicates that the hydrothermal vents are generally distributed over a landform of slope failure. These observations would imply that hydrothermal fluid rising up in the up-flow zone moves laterally as well when it comes near the seafloor, probably along numerous fractures and fissures in the caldera wall. The distribution of pre-existing faults and fractures may rather control the fluid flow pathways in the shallow part and condition the surface extent of the vent field.

Honsho, C.; Ura, T.; Kim, K.

2013-12-01

354

Recovery of iron from copper slag by deep reduction and magnetic beneficiation  

NASA Astrophysics Data System (ADS)

Aiming at recovering iron from high-iron-content copper slag, this article introduced a combination technology of deep reduction and magnetic beneficiation, investigated the iron recovery efficiency and optimized the technical conditions. When coke powder with 86wt% fixed carbon was used as a reductant, iron was successfully extracted from the copper slag. Under the optimized condition of the coke powder content of 14wt%, the calcium-to-silicon mass ratio (Ca/Si) of 0.2, the roasting temperature of 1300°C, the roasting time of 3 h, the grinding time of 20 min, and the magnetic field intensity of 61 kA·m-1, the iron recovery rate of the copper slag can reach 91.82%, and the extracted iron powder has an iron grade of 96.21%. With the characteristics of high iron grade and low impurity content, the extracted iron powder can be used as high-quality raw materials of weathering steel.

Li, Ke-qing; Ping, Shuo; Wang, Hong-yu; Ni, Wen

2013-11-01

355

Design and testing of planar magnetic micromotors fabricated by deep x-ray lithography and electroplating  

SciTech Connect

The successful design and testing of a three-phase planar integrated magnetic micromotor is presented. Fabrication is based on a modified deep X-ray lithography and electroplating or LIGA process. Maximum rotational speeds of 33,000 rpm are obtained in air with a rotor diameter of 285 {mu}m and do not change when operated in vacuum. Real time rotor response is obtained with an integrated shaft encoder. Long lifetime is evidenced by testing to over 5(10){sup 7} ration cycles without changes in performance. Projected speeds of the present motor configuration are in the vicinity of 100 krpm and are limited by torque ripple. Higher speeds, which are attractive for sensor applications. require constant torque characteristic excitation as is evidenced by ultracentrifuge and gyroscope design. Further understanding of electroplated magnetic material properties will drive these performance improvements.

Guckel, H.; Christenson, T.R.; Skrobis, K.J.; Klein, J. [Wisconsin Univ., Madison, WI (United States). Dept. of Electrical and Computer Engineering; Karnowsky, M. [Sandia National Labs., Albuquerque, NM (United States)

1993-05-01

356

More female patients and fewer stimuli per session are associated with the short-term antidepressant properties of repetitive transcranial magnetic stimulation (rTMS): a meta-analysis of 54 sham-controlled studies published between 1997–2013  

PubMed Central

Background Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) appears to have short-term antidepressant properties. The aim of the current study was to update our previous meta-analysis and to investigate factors associated with the antidepressant properties of rTMS. Method Following a systematic literature search conducted in Medline and PsycInfo, N=14 sham-controlled, parallel design studies (published after 2008 to August 2013) that had utilized rTMS of the DLPFC in major depression were included in the current meta-analysis. The sensitivity and moderator analyses also included data from N=40 studies (published in 1997–2008) from our previous meta-analysis. The effect size (Cohen’s d) in each study was the standardized difference in mean depression scores (on Hamilton Depression Rating Scale, Beck Depression Inventory, Montgomery Åsberg Depression Rating Scale) from baseline to final (after last session) in rTMS compared to sham groups. Results According to a random-effects model with inverse-variance weights, depression scores were significantly reduced after rTMS compared to sham in studies published from 2008–2013 based on N=659 patients (overall mean weighted d=?0.42, 95% confidence interval: ?0.66, ?0.18, P=0.001). Combining studies from our past and current meta-analyses (published in 1997–2013; N=54) revealed that depression was significantly reduced after left-fast (>1 Hz), right-slow (?1 Hz), and bilateral (or sequential) rTMS of DLPFC compared to sham. Significant antidepressant properties of rTMS were observed in studies with patients who were treatment resistant, unipolar (or bipolar), non-psychotic, medication-free (or started on antidepressants concurrently with rTMS). According to univariate meta-regressions, depression scores were significantly lower in studies with more female patients and fewer stimuli per session. There was little evidence that publication bias occurred in the analysis. Conclusion According to this study, the largest meta-analysis to date, short-term antidepressant properties of rTMS are independent of concurrent antidepressants and might depend on sex and the number of stimuli per session. PMID:24855360

Kedzior, Karina Karolina; Azorina, Valeriya; Reitz, Sarah Kim

2014-01-01

357

Transcranial direct current stimulation: A computer-based human model study  

Microsoft Academic Search

ObjectivesInterest in transcranial direct current stimulation (tDCS) in clinical practice has been growing, however, the knowledge about its efficacy and mechanisms of action remains limited. This paper presents a realistic magnetic resonance imaging (MRI)-derived finite element model of currents applied to the human brain during tDCS.

Tim Wagner; Felipe Fregni; Shirley Fecteau; Alan Grodzinsky; Markus Zahn; Alvaro Pascual-Leone

2007-01-01

358

Migraine-Mimicking Headache and Sickle Cell DiseaseA Transcranial Doppler Study  

Microsoft Academic Search

Headache occurs in sickle cell disease (SCD), but its characteristics and frequency have not previously been studied. Our aim was to study patterns of headache in adults with SCD and to correlate its presence with blood flow velocities measured by transcranial Doppler (TCD) and with brain magnetic resonance imaging (MRI) abnormalities. We studied 56 adults with SCD. Twenty-eight patients (50%)

GS Silva; P Vicari; HC Junior; MH Idagawa; AR Massaro

2006-01-01

359

Treatment of depression with transcranial direct current stimulation (tDCS): A Review  

Microsoft Academic Search

Major Depression Disorder (MDD) is usually accompanied by alterations of cortical activity and excitability, especially in prefrontal areas. These are reflections of a dysfunction in a distributed cortico-subcortical, bihemispheric network. Therefore it is reasonable to hypothesize that altering this pathological state with techniques of brain stimulation may offer a therapeutic target. Besides repetitive transcranial magnetic stimulation, tonic stimulation with weak

Michael A. Nitsche; Paulo S. Boggio; Felipe Fregni; Alvaro Pascual-Leone

2009-01-01

360

Structural setting and magnetic properties of pseudotachylyte in a deep crustal shear zone, western Canadian shield  

NASA Astrophysics Data System (ADS)

Seismic slip commonly produces pseudotachylytes, a glassy vein-filling substance that is typically interpreted as either a frictional melt or an ultra-triturated cataclasite. In either form, pseudotachylytes are commonly magnetite enriched, even in magnetite-free host rocks, and therefore are potentially useful as high fidelity recorders of natural magnetic fields at the time of slip in a wide array of lithologies. Pseudotachylytes generally have high magnetic susceptibility and thus should preserve the dominant field present as the material passes the Curie temperatures of magnetic minerals, primarily magnetite. Two potential sources have been proposed for the dominant magnetic field recorded: the earth's magnetic field at the time of slip or the temporary and orders of magnitude more intense field created by the presence of coseismic currents along the failure plane. Pseudotachylytes of the Cora Lake shear zone (CLsz) in the Athabasca Granulite Terrain, western Canadian shield, are consistently hosted in high strain ultramylonitic orthogneiss. Sinistral and extensional oblique-slip in the CLsz occurred at high-pressure granulite-grade conditions of ~1.0 GPa and >800°C and may have persisted to somewhat lower P-T conditions (~0.8 GPa, 700 °C) during ductile deformation. Pseudotachylyte-bearing slip surfaces have sinistral offset, matching the larger shear zone, and clasts of wall rock in the more brecciated veins display field evidence for ductile shear along the same plane prior to brittle failure. The presence of undeformed pseudotachylyte in kinematically compatible fracture arrays localized in ultramylonite indicates that brittle failure may have occurred in the waning stages of shear zone activity and at similar deep crustal conditions. Field-documented occurrences of pseudotachylyte include 2 cm-thick veins that run subparallel to mylonitic foliation and contain small flow-aligned clasts and large, heavily brecciated foliation-crosscutting zones up to seven centimeters thick. Field studies of pseudotachylytes in the Cora Lake shear zone confirm high magnetic susceptibility, both by strongly interfering with hand-held compasses and by testing with a hand-held magnetic susceptibility meter (over 7 x10-2 SI). More detailed laboratory analyses are planned in order to clarify the spatial association between veins of pseudotachylyte and areas of magnetic susceptibility. Investigation is also currently underway to determine if the remnant field preserved in these pseudotachylytes dominantly reflects a signature of the Earth's paleomagnetic field or that of a lightning-like coseismic current.

Orlandini, O. F.; Mahan, K. H.; Brown, L. L.; Regan, S.; Williams, M. L.

2012-12-01

361

Correlation of transcranial Doppler ultrasonography with MRI and MRA in the evaluation of sickle cell disease patients with prior stroke  

Microsoft Academic Search

We prospectively evaluated a group of patients with sickle cell disease and a clinical history of prior stroke, comparing transcranial Doppler sonography (TCD) to both magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) to determine its efficacy for the detection of flow abnormalities associated with prior cerebral infarction. Using MRI as the standard examination, there was 94% sensitivity and

M. S. Kogutt; S. S. Goldwag; K. L. Gupta; K. Kaneko; J. R. Humbert

1994-01-01

362

Deep X-Ray Lithography Based Fabrication of Rare-Earth Based Permanent Magnets and their Applications to Microactuators  

SciTech Connect

Precision high aspect-ratio micro molds constructed by deep x-ray lithography have been used to batch fabricate accurately shaped bonded rare-earth based permanent magnets with features as small as 5 microns and thicknesses up to 500 microns. Maximum energy products of up to 8 MGOe have been achieved with a 20%/vol. epoxy bonded melt-spun isotropic Nd2Fe14b powder composite. Using individually processed sub- millimeter permanent sections multipole rotors have been assembled. Despite the fact that these permanent magnet structures are small, their magnetic field producing capability remains the same as at any scale. Combining permanent magnet structures with soft magnetic materials and micro-coils makes possible new and more efficient magnetic microdevices.

Christenson, T.R.; Garino, T.J.; Venturini, E.L.

1999-01-27

363

Go-no-go task performance improvement after anodal transcranial DC stimulation of the left dorsolateral prefrontal cortex in major depression  

Microsoft Academic Search

BackgroundWe recently showed that repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) can affect the performance in an affective go-no-go (AGN) task. We aimed to extend this previous investigation testing whether one session of anodal transcranial direct current stimulation (tDCS) of the left DLPFC, as compared with anodal occipital and sham tDCS, affects this AGN task performance.

Paulo S. Boggio; Felix Bermpohl; Adriana O. Vergara; Ana L. C. R. Muniz; Fernanda H. Nahas; Priscila B. Leme; Sergio P. Rigonatti; Felipe Fregni

2007-01-01

364

Toroidal magnetic fields for protecting astronauts from ionizing radiation in long duration deep space missions  

NASA Astrophysics Data System (ADS)

Among the configurations of superconducting magnet structures proposed for protecting manned spaceships or manned deep space bases from ionizing radiation, toroidal ones are the most appealing for the efficient use of the magnetic field, being most of the incoming particle directions perpendicular to the induction lines of the field. The parameters of the toroid configuration essentially depend from the shape and volume of the habitat to be protected and the level of protection to be guaranteed. Two options are considered: (1) the magnetic system forming with the habitat a unique complex (compact toroid) to be launched as one piece; (2) the magnetic system to be launched separately from the habitat and assembled around it in space (large toroid). In first option the system habitat+toroid is assumed to have a cylindrical shape, with the toroid surrounding a cylindrical habitat, and launched with its axis on the axis of the launching system. The outer diameter is limited by the diameter of the shroud, which for present and foreseeable launching systems cannot be more than 9 m. The habitat is assumed to be 10 m long and have a 4 m diameter, leaving about 2 m all around for the protecting magnetic field. The volume of the habitat results about 100 m3, barely sufficient to a somewhat small crew (4-5 members) for a long duration (?2 years) mission. Technological problems and the huge magnetic pressure exerted on the inner cylindrical conductor of the toroid limit to not more than 4 T the maximum intensity of the magnetic field. With these parameters the mitigation of the dose inside the habitat due to the galactic cosmic rays (GCRs) is about 70% at minimum solar activity, while also most intense solar events cannot significantly contribute to the dose. The toroidal magnetic field can be produced by a large number of windings of the superconducting cable, arranged in cylindrical symmetry around the habitat to form continuous inner and outer cylindrical surfaces ('continuous' winding). In the option of separated launches for the habitat and the magnetic system, the volume of the habitat can be much larger, up to ?300 m3, i.e. a volume to be considered for a permanently manned space basis rather than for a spaceship. The toroidal field can occupy a larger volume around it, and indeed be less intense (B<3 T) for obtaining the same mitigation of the radiation dose inside the habitat. Also for the separate launches option several structural arrangements can be foreseen, depending from the considered number of windings. The limit of only two huge windings is the most attractive, as it minimizes the material and could be mechanically more stable, but it could be the most difficult to be assembled in space. Main parameters for the different configurations are reported, and the plan for the development of solutions and techniques is presented.

Papini, Paolo; Spillantini, Piero

2014-11-01

365

Magnetic fabrics in deformed metaperidotites of the Outokumpu Deep Drill Core, Finland: Implications for a major crustal shear zone  

NASA Astrophysics Data System (ADS)

The Outokumpu (OKU) assemblage was studied in drill cores from the 2516 m deep OKU Deep Drill Hole, Finland, and we observed that the strongest magnetic anomalies found in borehole measurements are related to three ferrimagnetic metaperidotite units with magnetic susceptibilities of up to 93 × 10- 3 SI separated by paramagnetic rock units. The main ferrimagnetic minerals are magnetite and minor pyrrhotite. Magnetic fabric studies were done in order to examine deformation within the OKU assemblage during the collisional deformation event 1.9 Ga ago. Well-defined magnetic axes (kmax, kmin) and nearly horizontal magnetic foliation subparallel to the macroscopic foliation occur at the top and the bottom of the OKU formation. Low- and high-field AMS measurements showed that ferri- and paramagnetic subfabrics are coaxial. Paramagnetic units intercalated between the ferrimagnetic units show mostly triaxial magnetic fabrics, and low degrees of magnetic anisotropy values (P? < 1.3) with a high variation of the shape factor (T) from prolate to oblate shapes. P? of the ferrimagnetic metaperidotite is high and range between 1.3 and 3.6 and T tends to more oblate shapes (T > 0). Ferrimagnetic unit 2 shows the highest magnetic susceptibility and P? up to 5.6, which is related to a high amount of magnetite and pyrrhotite mostly concentrated in huge aggregates and veins. Alignment of magnetic minerals parallel with the structural foliation and the high P? values in the ferrimagnetic metaperidotite indicate that magnetic fabric was acquired in a high strain zone. The magnetic fabrics represent shear zone (SC) fabrics, which have been formed during early obduction-related deformation of the Svecofennian orogeny. The stacked sequence of the ferri- and paramagnetic metaperidotite bodies can be interpreted as a thrust system with an imbricate fan, in which three individual listric thrust sheets occur. This interpretation is in accordance with previous tectonic models of the Outokumpu area.

Kontny, Agnes; Dietze, Frank

2014-08-01

366

Transcranial direct current stimulation for major depression: A general system for quantifying transcranial electrotherapy dosage  

Microsoft Academic Search

Opinion statement  There has been a recent resurgence of interest in therapeutic modalities using transcranial weak electrical stimulation through\\u000a scalp electrodes, such as transcranial direct current stimulation (tDCS), as a means of experimentally modifying and studying\\u000a brain function and possibly treating psychiatric conditions. A range of electrotherapy paradigms have been investigated, but\\u000a no consistent method has been indicated for reporting reproducible

Marom Bikson; Peter Bulow; John W. Stiller; Abhishek Datta; Fortunato Battaglia; Sergei V. Karnup; Teodor T. Postolache

2008-01-01

367

Modulation of moving phosphene thresholds by transcranial direct current stimulation of V1 in human  

Microsoft Academic Search

Small moving sensations, so-called moving phosphenes are perceived, when V5, a visual area important for visual motion analysis, is stimulated by transcranial magnetic stimulation (TMS). However, it is still a matter of debate if only V5 takes part in movement perception or other visual areas are also involved in this process. In this study we tested the involvement of V1

Andrea Antal; Tamás Z. Kincses; Michael A. Nitsche; Walter Paulus

2003-01-01

368

Deep-Sea Magnetics on Active and Fossil Hydrothermal Sites: a Tool to Detect and Characterize Submarine Ore Deposits  

NASA Astrophysics Data System (ADS)

Since the first discoveries of hydrothermal sites at mid-ocean ridges in the 70s, international efforts in the deep seafloor exploration have unravelled a wide variety of hydrothermal sites in terms of geological settings, physical parameters, and biological communities as well. Such efforts, coordinated in the InterRidge program since 1992, are becoming even more important when the increasing need in metals for developing economies makes the exploitation of metal sulfides accumulated at deep-sea hydrothermal sites a realistic target. The usual method to find hydrothermal sites is to detect the associated chemical plumes enriched in manganese, methane, hydrogen, helium 3, in the water column. How efficient it has been proven, such a method is limited to the search for active hydrothermal vents. Active vents, however, are not the best places for mining the seafloor, because (1) they host massive sulfides deposits in the making and may not represent the largest accumulation; (2) they are still very hot and would rapidly damage the mining tools; and, last but not the least, (3) they host fragile and precious ecosystem that could be dramatically affected by mining operations. Methods to find fossil hydrothermal sites (i.e. colder and devoid of specific ecosystems) include systematic rock sampling - a very tedious endeavour - and high resolution, near seafloor geophysical surveys. Existing magnetic surveys on basalt-hosted, peridotite-hosted and sediment-hosted sites revealed different types of signatures, which reflect the magnetizations of the host rock and the ore deposit, among others. Basalt-hosted sites exhibit negative magnetic anomalies, i.e. a deficit of magnetization, due to thermal demagnetization and hydrothermal alteration of the highly magnetic basalt, whereas both peridotite-hosted and sediment-hosted sites show positive anomalies, i.e. an excess of magnetization, clearly associated with the ore deposit. Results from recent cruises Serpentine (R/V Pourquoi pas?, 2007) and MoMARDream (R/V L'Atalante, 2008), both using ROV Victor of IFREMER, on basalt and ultramafic-hosted sites of the Mid-Atlantic Ridge, will be presented. High resolution, deep-sea magnetic investigations may therefore significantly contribute to the detection and characterization of active and fossil sites and to the evaluation of their mining potential, for instance through a fleet of small AUV exploring systematically the deep seafloor.

Dyment, J.; Szitkar, F.; Fouquet, Y.; Choi, Y.

2011-12-01

369

Massive Transcranial Parotid Pleomorphic Adenoma: Recurrence after 30 Years*  

PubMed Central

Pleomorphic adenoma, also known as benign mixed tumor, is the most common tumor affecting the parotid gland and can reach massive size; however, intracranial invasion is rare. Recurrence of pleomorphic adenoma after excision is a well-known phenomenon and can present decades after resection of the primary tumor. Here we present the case of a 53-year-old man who presented to our clinic with ear fullness, otalgia, and hearing loss 30 years after undergoing total parotidectomy and external beam radiotherapy for pleomorphic adenoma. Magnetic resonance imaging revealed a massive transcranial tumor invading the mastoid cavity, the dura of the posterior fossa, the fallopian and semicircular canals, the jugular foramen, the lateral infratemporal fossa skull base, the sigmoid and transverse sinuses, and the superior parapharyngeal region. Gross examination and histopathological studies confirmed that the mass was a recurrent pleomorphic adenoma. Here we discuss the features of recurrent pleomorphic adenoma and review the current literature. PMID:23946917

Strub, Graham M.; Georgolios, Alexandros; Graham, Robert S.; Powers, Celeste N.; Coelho, Daniel H.

2012-01-01

370

Transcranial Direct Current Stimulation Augments Perceptual Sensitivity and 24-Hour Retention in a  

E-print Network

Transcranial Direct Current Stimulation Augments Perceptual Sensitivity and 24-Hour Retention Abstract We have previously shown that transcranial direct current stimulation (tDCS) improved performance) Transcranial Direct Current Stimulation Augments Perceptual Sensitivity and 24-Hour Retention in a Complex

Parasuraman, Raja

371

Empirical research Enhancing vigilance in operators with prefrontal cortex transcranial direct current  

E-print Network

2012 Available online xxxx Keywords: Noninvasive brain stimulation Transcranial direct current prefrontal transcranial direct current stimulation (tDCS) at one of two different time points duringEmpirical research Enhancing vigilance in operators with prefrontal cortex transcranial direct

Parasuraman, Raja

372

MR-guided transcranial brain HIFU in small animal models  

NASA Astrophysics Data System (ADS)

Recent studies have demonstrated the feasibility of transcranial high-intensity focused ultrasound (HIFU) therapy in the brain using adaptive focusing techniques. However, the complexity of the procedures imposes provision of accurate targeting, monitoring and control of this emerging therapeutic modality in order to ensure the safety of the treatment and avoid potential damaging effects of ultrasound on healthy tissues. For these purposes, a complete workflow and setup for HIFU treatment under magnetic resonance (MR) guidance is proposed and implemented in rats. For the first time, tissue displacements induced by the acoustic radiation force are detected in vivo in brain tissues and measured quantitatively using motion-sensitive MR sequences. Such a valuable target control prior to treatment assesses the quality of the focusing pattern in situ and enables us to estimate the acoustic intensity at focus. This MR-acoustic radiation force imaging is then correlated with conventional MR-thermometry sequences which are used to follow the temperature changes during the HIFU therapeutic session. Last, pre- and post-treatment magnetic resonance elastography (MRE) datasets are acquired and evaluated as a new potential way to non-invasively control the stiffness changes due to the presence of thermal necrosis. As a proof of concept, MR-guided HIFU is performed in vitro in turkey breast samples and in vivo in transcranial rat brain experiments. The experiments are conducted using a dedicated MR-compatible HIFU setup in a high-field MRI scanner (7 T). Results obtained on rats confirmed that both the MR localization of the US focal point and the pre- and post-HIFU measurement of the tissue stiffness, together with temperature control during HIFU are feasible and valuable techniques for efficient monitoring of HIFU in the brain. Brain elasticity appears to be more sensitive to the presence of oedema than to tissue necrosis.

Larrat, B.; Pernot, M.; Aubry, J.-F.; Dervishi, E.; Sinkus, R.; Seilhean, D.; Marie, Y.; Boch, A.-L.; Fink, M.; Tanter, M.

2010-01-01

373

The value of transcranial Doppler derived pulsatility index for diagnosing cerebral small-vessel disease  

PubMed Central

Background: The pulsatility index (PI), measured by transcranial Doppler (TCD) ultrasonography, can reflect vascular resistance induced by cerebral small-vessel disease (SVD). We evaluated the value of TCD-derived PI for diagnosing SVD as compared with magnetic resonance imaging (MRI). Materials and Methods: Fifty-six consecutive cases with SVD (based on MRI) and 48 controls with normal MRI underwent TCD. Based on MRI findings, patients were categorized into five subgroups of preventricular hyperintensity (PVH), deep white matter hyperintensity (DWMH), lacunar, pontin hyperintensity (PH), and PVH+DWMH+lacunar. The sensitivity and specificity of TCD in best PI cut-off points were calculated in each group. Results: The sensitivity and specificity of TCD in comparison with MRI with best PI cut-off points were as follows: In PVH with PI = 0.83, the sensitivity and specificity was 90% and 98%, respectively. In DWMH with PI = 0.79, the sensitivity and specificity was 75% and 87.5%, respectively. In lacunar with PI = 0.80, the sensitivity and specificity was 73% and 90%, respectively. In PH with PI = 0.69, the sensitivity and specificity was 92% and 87.5%, respectively. And, in PVH+DWMH+lacunar subgroup with PI = 0.83, the sensitivity and specificity was 90% and 96%, respectively. Conclusions: Increased TCD derived PI can accurately indicate the SVD. Hence, TCD can be used as a non-invasive and inexpensive method for diagnosing SVD, and TCD-derived PI can be considered as a physiologic index of the disease as well.

Ghorbani, Abbas; Ahmadi, Mohammad Javad; Shemshaki, Hamidreza

2015-01-01

374

Absolute magnetization of the seafloor at a basalt-hosted hydrothermal site: Insights from a deep-sea submersible survey  

NASA Astrophysics Data System (ADS)

The analysis of high-resolution vector magnetic data acquired by deep-sea submersibles (DSSs) requires the development of specific approaches adapted to their uneven tracks. We present a method that takes advantage of (1) the varying altitude of the DSS above the seafloor and (2) high-resolution multibeam bathymetric data acquired separately, at higher altitude, by an Autonomous Underwater Vehicle, to estimate the absolute magnetization intensity and the magnetic polarity of the shallow subseafloor along the DSS path. We apply this method to data collected by DSS Nautile on a small active basalt-hosted hydrothermal site. The site is associated with a lack of magnetization, in agreement with previous findings at the same kind of sites: the contrast between nonmagnetic sulfide deposits/stockwork zone and strongly magnetized basalt is sufficient to explain the magnetic signal observed at such a low altitude. Both normal and reversed polarities are observed in the lava flows surrounding the site, suggesting complex history of accumulating volcanic flows.

Szitkar, Florent; Dyment, Jérôme; Fouquet, Yves; Choi, Yujin; Honsho, Chie

2015-02-01

375

In Vivo Magnetization Transfer and Diffusion-Weighted Magnetic Resonance Imaging Detects Thrombus Composition in a Mouse Model of Deep Vein Thrombosis  

PubMed Central

Background Deep vein thrombosis remains a major health problem necessitating accurate diagnosis. Thrombolysis is associated with significant morbidity and is effective only for the treatment of unorganized thrombus. We tested the feasibility of in vivo magnetization transfer (MT) and diffusion-weighted magnetic resonance imaging to detect thrombus organization in a murine model of deep vein thrombosis. Methods and Results Deep vein thrombosis was induced in the inferior vena cava of male BALB/C mice. Magnetic resonance imaging was performed at days 1, 7, 14, 21, and 28 after thrombus induction using MT, diffusion-weighted, inversion-recovery, and T1-mapping protocols. Delayed enhancement and T1 mapping were repeated 2 hours after injection of a fibrin contrast agent. Finally, excised thrombi were used for histology. We found that MT and diffusion-weighted imaging can detect histological changes associated with thrombus aging. MT rate (MTR) maps and percentage of MT rate (%MTR) allowed visualization and quantification of the thrombus protein content, respectively. The %MTR increased with thrombus organization and was significantly higher at days 14, 21, and 28 after thrombus induction (days 1, 7, 14, 21, 28: %MTR=2483±451, 2079±1210, 7029±2490, 10 295±4356, 32 994±25 449; Panova<0.05). There was a significant positive correlation between the %MTR and the histological protein content of the thrombus (r=0.70; P<0.05). The apparent diffusion coefficient was lower in erythrocyte-rich and collagen-rich thrombus (0.72±0.10 and 0.69±0.05 [×10?3 mm2/s]). Thrombus at days 7 and 14 had the highest apparent diffusion coefficient values (0.95±0.09 and 1.10±0.18 [×10?3 mm2/s]). Conclusions MT and diffusion-weighted magnetic resonance imaging sequences are promising for the staging of thrombus composition and could be useful in guiding medical intervention. PMID:23564561

Saha, Prakash; Modarai, Bijan; Smith, Alberto; Botnar, René M.

2014-01-01

376

Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation  

PubMed Central

In this paper we demonstrate in the intact human the possibility of a non-invasive modulation of motor cortex excitability by the application of weak direct current through the scalp.Excitability changes of up to 40 %, revealed by transcranial magnetic stimulation, were accomplished and lasted for several minutes after the end of current stimulation.Excitation could be achieved selectively by anodal stimulation, and inhibition by cathodal stimulation.By varying the current intensity and duration, the strength and duration of the after-effects could be controlled.The effects were probably induced by modification of membrane polarisation. Functional alterations related to post-tetanic potentiation, short-term potentiation and processes similar to postexcitatory central inhibition are the likely candidates for the excitability changes after the end of stimulation. Transcranial electrical stimulation using weak current may thus be a promising tool to modulate cerebral excitability in a non-invasive, painless, reversible, selective and focal way. PMID:10990547

Nitsche, M A; Paulus, W

2000-01-01

377

Deep-tow magnetic anomaly study of the Pacific Jurassic Quiet Zone and implications for the geomagnetic polarity reversal timescale and  

E-print Network

., 113, B07110, doi:10.1029/2007JB005527. 1. Introduction [2] The Jurassic period appears to be a time of the Jurassic magnetic field. It was once suggested that this Jurassic ``Quiet Zone'' (JQZ) reflects a periodDeep-tow magnetic anomaly study of the Pacific Jurassic Quiet Zone and implications

378

Characterization of deep geothermal energy resources using Electro-Magnetic methods, Belgium  

NASA Astrophysics Data System (ADS)

Sedimentary basins in Northwest Europe have significant potential for low to medium enthalpy, deep geothermal energy resources. These resources are currently assessed using standard exploration techniques (seismic investigations followed by drilling of a borehole). This has enabled identification of geothermal resources but such techniques are extremely costly. The high cost of exploration remains one of the main barriers to geothermal project development due to the lack of capital in the geothermal industry. We will test the possibility of using the Electro-Magnetic (EM) methods to aid identification of geothermal resources in conjunction with more traditional exploration methods. An EM campaign could cost a third of a seismic campaign and is also often a passive technology, resulting in smaller environmental impacts than seismic surveys or drilling. EM methods image changes in the resistivity of the earth's sub-surface using natural or induced frequency dependant variations of electric and magnetic fields. Changes in resistivity can be interpreted as representing different subsurface properties including changes in rock type, chemistry, temperature and/or hydraulic transmissivity. While EM techniques have proven to be useful in geothermal exploration in high enthalpy areas in the last 2-3 years only a handful of studies assess their applicability in low enthalpy sedimentary basins. Challenges include identifying which sub-surface features cause changes in electrical resistivity as low enthalpy reservoirs are unlikely to exhibit the hydrothermally altered clay layer above the geothermal aquifer that is typical for high enthalpy reservoirs. Yet a principal challenge is likely to be the high levels of industrialisation in the areas of interest. Infrastructure such as train tracks and power cables can create a high level of background noise that can obfuscate the relevant signal. We present our plans for an EM campaign in the Flemish region of Belgium. Field techniques will be developed to increase the signal-noise ratio and identify background noise. Firstly, surface noise will be filtered off by non-parametric approaches such as proper orthogonal decomposition. Secondly, the EM signal and newly acquired seismic data will be combined to obtain a multi-dimensional earth model via an inversion process. Typically, these identification procedures are non-unique, resulting in multiple possible scenarios that cannot be distinguished based on the information at hand. To this end standard approaches) use a regularisation term including an apriori model. Here, Bayesian approaches will also be used, in which expert knowledge is used to guide the outcome to reasonable solutions. We will assess the reduction in uncertainty and therefore risks that EM methods can provide when used in combination with seismic surveys for geothermal exploration prior to drilling. It may also be possible to use this technique for monitoring the evolution of geothermal systems. Such techniques may prove to be extremely valuable for the future development of geothermal energy resources.

Loveless, Sian; Harcout-Menou, Virginie; De Ridder, Fjo; Claessens, Bert; Laenen, Ben

2014-05-01

379

Spectral image reconstruction for transcranial ultrasound measurement  

PubMed Central

An approach aimed at improved ultrasound resolution and signal strength through highly attenuating media is presented. The method delivers a series of multiple-cycle bursts in order to construct a discrete spectral (frequency domain) response in one dimension. Cross-correlation of this ultrasound A-mode response with its transmitted signal results in time-localized peaks that correspond to scattering locations. The approach is particularly relevant to the problem of transcranial ultrasound imaging, as it combines numerous smaller signals into a single signal whose net power may exceed that which could be achieved using a single burst. Tests are performed with human skull fragments and nylon-wire targets embedded in a tissue phantom. Skulls are oriented to produce both lateral and shear modes of transcranial propagation. A total of 9 locations distributed over three ex vivo human skull samples are studied. Compared with pulsed and chirped signals, results indicate more localized peaks when using the multi-cycle approach, with more accurate positioning when combined with the transcranial shear mode. PMID:16306652

Clement, Greg T.

2005-01-01

380

Spectral image reconstruction for transcranial ultrasound measurement  

NASA Astrophysics Data System (ADS)

An approach aimed at improved ultrasound resolution and signal strength through highly attenuating media is presented. The method delivers a series of multiple-cycle bursts in order to construct a discrete spectral (frequency domain) response in one dimension. Cross-correlation of this ultrasound A-mode response with its transmitted signal results in time-localized peaks that correspond to scattering locations. The approach is particularly relevant to the problem of transcranial ultrasound imaging, as it combines numerous smaller signals into a single signal whose net power may exceed that which could be achieved using a single burst. Tests are performed with human skull fragments and nylon-wire targets embedded in a tissue phantom. Skulls are oriented to produce both lateral and shear modes of transcranial propagation. A total of nine locations distributed over three ex vivo human skull samples are studied. Compared with pulsed and chirped signals, results indicate more localized peaks when using the multi-cycle approach, with more accurate positioning when combined with the transcranial shear mode.

Clement, Greg T.

2005-12-01

381

Parietal transcranial direct current stimulation modulates primary motor cortex excitability.  

PubMed

The posterior parietal cortex is part of the cortical network involved in motor learning and is structurally and functionally connected with the primary motor cortex (M1). Neuroplastic alterations of neuronal connectivity might be an important basis for learning processes. These have however not been explored for parieto-motor connections in humans by transcranial direct current stimulation (tDCS). Exploring tDCS effects on parieto-motor cortical connectivity might be functionally relevant, because tDCS has been shown to improve motor learning. We aimed to explore plastic alterations of parieto-motor cortical connections by tDCS in healthy humans. We measured neuroplastic changes of corticospinal excitability via motor evoked potentials (MEP) elicited by single-pulse transcranial magnetic stimulation (TMS) before and after tDCS over the left posterior parietal cortex (P3), and 3 cm posterior or lateral to P3, to explore the spatial specificity of the effects. Furthermore, short-interval intracortical inhibition/intracortical facilitation (SICI/ICF) over M1, and parieto-motor cortical connectivity were obtained before and after P3 tDCS. The results show polarity-dependent M1 excitability alterations primarily after P3 tDCS. Single-pulse TMS-elicited MEPs, M1 SICI/ICF at 5 and 7 ms and 10 and 15 ms interstimulus intervals (ISIs), and parieto-motor connectivity at 10 and 15 ms ISIs were all enhanced by anodal stimulation. Single pulse-TMS-elicited MEPs, and parieto-motor connectivity at 10 and 15 ms ISIs were reduced by cathodal tDCS. The respective corticospinal excitability alterations lasted for at least 120 min after stimulation. These results show an effect of remote stimulation of parietal areas on M1 excitability. The spatial specificity of the effects and the impact on parietal cortex-motor cortex connections suggest a relevant connectivity-driven effect. PMID:25645274

Rivera-Urbina, Guadalupe Nathzidy; Batsikadze, Giorgi; Molero-Chamizo, Andrés; Paulus, Walter; Kuo, Min-Fang; Nitsche, Michael A

2015-03-01

382

Ground States of Ultracold Spin-1 Atoms in a Deep Double-Well Optical Superlattice in a Weak Magnetic Field  

NASA Astrophysics Data System (ADS)

The ground states of the ultracold spin-1 atoms trapped in a deep one-dimensional double-well optical superlattice in a weak magnetic field are obtained. It is shown that the ground-state diagrams of the reduced double-well model are remarkably different for the antiferromagnetic and ferromagnetic condensates. The transition between the singlet state and nematic state is observed for the antiferromagnetic interaction atoms, which can be realized by modulating the tunneling parameter or the quadratic Zeeman energy. An experiment to distinguish the different spin states is suggested.

Zheng, Gong-Ping; Qin, Shuai-Feng; Wang, Shou-Yang; Jian, Wen-Tian

2013-04-01

383

Electronic and magnetic structures of the postperovskite-type Fe2O3 and implications for planetary magnetic records and deep interiors.  

PubMed

Recent studies have shown that high pressure (P) induces the metallization of the Fe(2+)-O bonding, the destruction of magnetic ordering in Fe, and the high-spin (HS) to low-spin (LS) transition of Fe in silicate and oxide phases at the deep planetary interiors. Hematite (Fe(2)O(3)) is an important magnetic carrier mineral for deciphering planetary magnetism and a proxy for Fe in the planetary interiors. Here, we present synchrotron Mössbauer spectroscopy and X-ray diffraction combined with ab initio calculations for Fe(2)O(3) revealing the destruction of magnetic ordering at the hematite --> Rh(2)O(3)-II type (RhII) transition at 70 GPa and 300 K, and then the revival of magnetic ordering at the RhII --> postperovskite (PPv) transition after laser heating at 73 GPa. At the latter transition, at least half of Fe(3+) ions transform from LS to HS and Fe(2)O(3) changes from a semiconductor to a metal. This result demonstrates that some magnetic carrier minerals may experience a complex sequence of magnetic ordering changes during impact rather than a monotonic demagnetization. Also local Fe enrichment at Earth's core-mantle boundary will lead to changes in the electronic structure and spin state of Fe in silicate PPv. If the ultra-low-velocity zones are composed of Fe-enriched silicate PPv and/or the basaltic materials are accumulated at the lowermost mantle, high electrical conductivity of these regions will play an important role for the electromagnetic coupling between the mantle and the core. PMID:19279204

Shim, Sang-Heon; Bengtson, Amelia; Morgan, Dane; Sturhahn, Wolfgang; Catalli, Krystle; Zhao, Jiyong; Lerche, Michael; Prakapenka, Vitali

2009-04-01

384

Electronic and magnetic structures of the postperovskite-type Fe2O3 and implications for planetary magnetic records and deep interiors  

PubMed Central

Recent studies have shown that high pressure (P) induces the metallization of the Fe2+–O bonding, the destruction of magnetic ordering in Fe, and the high-spin (HS) to low-spin (LS) transition of Fe in silicate and oxide phases at the deep planetary interiors. Hematite (Fe2O3) is an important magnetic carrier mineral for deciphering planetary magnetism and a proxy for Fe in the planetary interiors. Here, we present synchrotron Mössbauer spectroscopy and X-ray diffraction combined with ab initio calculations for Fe2O3 revealing the destruction of magnetic ordering at the hematite ? Rh2O3-II type (RhII) transition at 70 GPa and 300 K, and then the revival of magnetic ordering at the RhII ? postperovskite (PPv) transition after laser heating at 73 GPa. At the latter transition, at least half of Fe3+ ions transform from LS to HS and Fe2O3 changes from a semiconductor to a metal. This result demonstrates that some magnetic carrier minerals may experience a complex sequence of magnetic ordering changes during impact rather than a monotonic demagnetization. Also local Fe enrichment at Earth's core-mantle boundary will lead to changes in the electronic structure and spin state of Fe in silicate PPv. If the ultra-low-velocity zones are composed of Fe-enriched silicate PPv and/or the basaltic materials are accumulated at the lowermost mantle, high electrical conductivity of these regions will play an important role for the electromagnetic coupling between the mantle and the core. PMID:19279204

Shim, Sang-Heon; Bengtson, Amelia; Morgan, Dane; Sturhahn, Wolfgang; Catalli, Krystle; Zhao, Jiyong; Lerche, Michael; Prakapenka, Vitali

2009-01-01

385

Transcranial direct current stimulation: State of the art 2008  

E-print Network

Transcranial direct current stimulation: State of the art 2008 Michael A. Nitsche, MDa , Leonardo G. Beyond this, transcranial direct current stimulation (tDCS) of different cortical areas has been shown direct currents is a promising tool in human neuroscience and neurobehavioral research. To facilitate

Miall, Chris

386

Cerebral Microembolism Detected by Transcranial Doppler During Cardiac Procedures  

Microsoft Academic Search

Background and Purpose—Cerebral embolism with clinical sequelae may rarely complicate cardioversion and cardiac catheterization. Transcranial Doppler sonography has recently been introduced to monitor microemboli entering the middle cerebral artery in cardiac and carotid surgery. We therefore used this technique to evaluate the risk of asymptomatic embolism during common cardiac procedures. Methods—Patients were monitored by transcranial Doppler while undergoing direct current

Jan Stygall; Robert Kong; J. Malcolm Walker; Suzanna M. C. Hardman; Michael J. G. Harrison; Stanton P. Newman; Dip Psych

2010-01-01

387

Boosting brain excitability by transcranial high frequency stimulation in the ripple range  

PubMed Central

Alleviating the symptoms of neurological diseases by increasing cortical excitability through transcranial stimulation is an ongoing scientific challenge. Here, we tackle this issue by interfering with high frequency oscillations (80–250 Hz) via external application of transcranial alternating current stimulation (tACS) over the human motor cortex (M1). Twenty-one subjects participated in three different experimental studies and they received on separate days tACS at three frequencies (80 Hz, 140 Hz and 250 Hz) and sham stimulation in a randomized order. tACS with 140 Hz frequency increased M1 excitability as measured by transcranial magnetic stimulation-generated motor evoked potentials (MEPs) during and for up to 1 h after stimulation. Control experiments with sham and 80 Hz stimulation were without any effect, and 250 Hz stimulation was less efficient with a delayed excitability induction and reduced duration. After-effects elicited by 140 Hz stimulation were robust against inversion of test MEP amplitudes seen normally under activation. Stimulation at 140 Hz reduced short interval intracortical inhibition, but left intracortical facilitation, long interval cortical inhibition and cortical silent period unchanged. Implicit motor learning was not facilitated by 140 Hz stimulation. High frequency stimulation in the ripple range is a new promising non-invasive brain stimulation protocol to increase human cortical excitability during and after the end of stimulation. PMID:20962008

Moliadze, Vera; Antal, Andrea; Paulus, Walter

2010-01-01

388

Imaging of current density and current pathways in rabbit brain during transcranial electrostimulation.  

PubMed

A magnetic resonance imaging (MRI) method was used for a noninvasive study of current density (CD) and current pathways (CP's) inside the skull during transcranial electrostimulation in rabbits. The transcranial impulse current directions studied were those previously used in transcranial electric treatment either sagittally or bilaterally. MRI data were collected from slices perpendicular to the direction of current application. In these slices, only the perpendicular component of the CD was measured. Computer methods for accurate topographic mapping of the main areas with high CD and for reconstruction of CP's are described. It was revealed that current applied on the head sagittally passed mostly through the cerebrospinal fluid in the basal brain cisternas connected in series, and through the anterior horns of the lateral ventricles, foramina of Monro, ventrocaudal part of the third ventricle, aqueductus, and fourth ventricle. Possible connections between these CP's are suggested. Bilaterally applied current passed through the brain and skull core more diffusely without concentrations in cisternas and ventricles. The results of the present study suggest an explanation for the observation that sagittally applied current more effectively stimulates brain structures with antinociceptive function and elicits more pronounced analgesic effect. PMID:10493077

Joy, M L; Lebedev, V P; Gati, J S

1999-09-01

389

Violation of the Guiding Center Approximation for Energetic Ions in the Deep Inner Magnetosphere during Magnetic Storms  

NASA Astrophysics Data System (ADS)

During a magnetic storm, the ring current is developed in the inner magnetosphere. It is believed that the decrease of Dst index during a strom is mainly due to the development of the ring current. Recent numerical simulations have revealed how the ring current grows and decays (Lemon et al., 2004; Zaharia et al., 2006) in the self-consistent field with the guiding center approximation (GCA). This approximation breaks down if the spatial scale of the magnetic field change is comparable to the gyroradius. From the following two reasons, we suspect an approach to treat motion of ring current oxygen ions with the GCA. (1) During magnetic storms a dominant part of energy density of the ring current is carried by oxygen ions (Daglis at al., 1999) which are 16 times heavier than protons; that is, gyroradius of oxygen ions is 4 times larger than that of protons with the same kinetic energy. (2) Magnetic field configuration becomes far deviated from dipole field even in the deep inner magnetosphere. In this study, we examine whether the GCA is valid for ring current ions, in particular for oxygen ions. We compared energetic ion trajectories computed by the Lorentz equation and those by the GCA equation (Northrop, 1963). We used the TS04 (Tsyganenko and Sitnov, 2005) magnetic field model as well as the Volland-Stern (Volland 1973; Stern 1975) electric field model. In case of integration of the Lorentz equation, we found that some of ions have different trajectories from those of the GCA equation. Most remarkable results can be summarized as follows. First, ions having a pitch angle of ~90 degrees do not conserve the first adiabatic invariant and gradually increase their amplitude of bouncing motion around the magnetic equator. Second, an ion with a large gyroradius (i.e, an energetic oxygen ion) can be accelerated thorough the meandering motion even in the deep inner magnetosphere. Above-mentioned results lead some interest phenomena, for example, pitch angle distribution or the development of the ring current. Therefore, we suggest that GCA may not describe the ring current development and decay appropriately.

Shibahara, K.; Nose, M.

2009-12-01

390

MRI-based magnetic navigation of nanomedical devices for drug delivery and hyperthermia in deep tissues  

Microsoft Academic Search

Magnetic resonance imaging (MRI) scanners can be used with minimum upgrades as integrated platforms for targeted delivery of micro\\/nanoparticles in the human body. In addition to being widespread in hospitals, they provide real-time tracking, control and means of propulsion for magnetic devices without penetration depth limitations. From these positive features, MRI appears as the perfect central element of a nanomedical

Jean-Baptiste Mathieu; Sylvain Martel

2007-01-01

391

Deep TMS add-on treatment for intractable Tourette syndrome: A feasibility study.  

PubMed

Objectives. In a considerable minority of patients who suffer from Tourette syndrome (TS) the disorder persists into adulthood and is associated with severe symptoms and limited therapeutic options. Repetitive transcranial magnetic stimulation (rTMS) to the supplementary motor area (SMA) has shown promising therapeutic results. Deep rTMS is a novel technology that enables deeper non-invasive cortical stimulation. This open-label pilot study is the first to examine the possible role of deep rTMS as add-on treatment for intractable TS. Methods. Twelve patients were recruited in order to examine bilateral SMA inhibition via deep TMS using the HBDL coil, as a possible treatment for adult TS treatment-resistant patients. Two patients did not complete the 20-day study protocol. Results. There were no significant side effects. While tics did not improve among the group as a whole, the subgroup of six patients with combined TS and OCD (obsessive compulsive syndrome) showed significant improvement in tic severity (P = 0.037). Conclusions. These findings support the safety of deep rTMS for treating TS. The results also highlight the importance of studying the different TS syndromes separately (e.g., with or without OCD comorbidity) when evaluating deep rTMS protocols for TS patients. PMID:25342253

Bloch, Yuval; Arad, Shira; Levkovitz, Yechiel

2014-10-24

392

Integrated Analysis on Gravity and Magnetic Fields of the Hailar Basin, NE China: Implications for Basement Structure and Deep Tectonics  

NASA Astrophysics Data System (ADS)

The Hailar Basin is one of the most representative basins among the Northeast China Basin Group, which is situated in the east of East Asia Orogene between the Siberia Plate and the North China Plate. Based on the detailed analysis of the Bouguer gravity anomaly, aeromagnetic anomaly as well as petrophysical data, we studied the features of gravity-magnetic fields in the basin and its neighboring areas. A combined approach of Wavelet Multi-scale Decomposition and Power Spectrum Analysis was adopted to quantitatively grade the gravity and magnetic anomalies into four levels. Accordingly, the apparent depths of the source fields can be assessed. The results reveal the crustal density and magnetic structures of the Hailar Basin. Low-order wavelet details of gravity-magnetic anomalies were carried out on studying basin basement structure. Seven major basement faults of the basin were identified, and the basement lithology was discussed and predicted. Three major uplifts and 14 depressions were delineated according to basement depth inversion by the Park method. High-order wavelet approximations of gravity-magnetic anomalies were carried out on studying deep tectonics of the basin. The average Moho depth of the study area is about 40 km, with a mantle uplift located in the northeast of the basin. The average depth of the Curie interface is about 19 km, while the uplift of the Curie interface is in the basin center and its east and west sides are depressions. Finally, inversion of Bouguer gravity anomalies was conducted on an across-basin GGT profile using the Wavelet Multi-scale Decomposition. The inversion results are consistent with those of GGT seismic inversion, suggesting that the Wavelet Multi-scale Decomposition can be applied to distinguish major crustal density interfaces.

Sun, B.; Wang, L.; Dong, P.; Scientific Team Of Applied Geophysics

2010-12-01

393

Acute stroke: therapeutic transcranial color duplex sonography.  

PubMed

The enhancement of thrombolysis by ultrasound energy (sonothrombolysis) is an emerging field of interest in the treatment of acute ischemic stroke. Recent in vitro and clinical studies have investigated the effects of using transcranially applied 'diagnostic' ultrasound for this purpose. Using transcranial color duplex sonography (TCDS) allows an examiner to identify the site of occlusion and focus the ultrasound beam on it. Clinical studies using TCDS to enhance thrombolysis in acute middle cerebral artery occlusions have revealed an accelerating effect on recanalization, as well as a tendency for a better outcome. Data from small sample studies suggest that this effect on recanalization is present not only in combination with recombinant tissue plasminogen activator (rt-PA), but also with any thrombolytic drug. However, when TCDS was used in combination with rt-PA, an increase in the rate of asymptomatic and symptomatic intracerebral hemorrhages tended to occur compared to patients treated with thrombolysis alone. Larger sample-sized clinical studies should be conducted in the future to evaluate the safety and efficacy of using TCDS for sonothrombolysis. This method should also be further developed to determine its effect when used in combination with other types of ultrasound and thrombolytic drugs. PMID:17290135

Eggers, Jürgen

2006-01-01

394

Transcranial photoacoustic tomography of the monkey brain  

NASA Astrophysics Data System (ADS)

A photoacoustic tomography (PAT) system using a virtual point ultrasonic transducer was developed for transcranial imaging of monkey brains. The virtual point transducer provided a 10 times greater field-of-view (FOV) than finiteaperture unfocused transducers, which enables large primate imaging. The cerebral cortex of a monkey brain was accurately mapped transcranially, through up to two skulls ranging from 4 to 8 mm in thickness. The mass density and speed of sound distributions of the skull were estimated from adjunct X-ray CT image data and utilized with a timereversal algorithm to mitigate artifacts in the reconstructed image due to acoustic aberration. The oxygenation saturation (sO2) in blood phantoms through a monkey skull was also imaged and quantified, with results consistent with measurements by a gas analyzer. The oxygenation saturation (sO2) in blood phantoms through a monkey skull was also imaged and quantified, with results consistent with measurements by a gas analyzer. Our experimenta