Sample records for deep transcranial magnetic

  1. Coil Design Considerations for Deep Transcranial Magnetic Stimulation

    PubMed Central

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

    2014-01-01

    Objectives To explore the field characteristics and design tradeoffs of coils for deep transcranial magnetic stimulation (dTMS). Methods We simulated parametrically two dTMS coil designs on a spherical head model using the finite element method, and compare them with five commercial TMS coils, including two that are FDA approved for the treatment of depression (ferromagnetic-core figure-8 and H1 coil). Results Smaller coils have a focality advantage over larger coils; however, this advantage diminishes with increasing target depth. Smaller coils have the disadvantage of producing stronger field in the superficial cortex and requiring more energy. When the coil dimensions are large relative to the head size, the electric field decay in depth becomes linear, indicating that, at best, the electric field attenuation is directly proportional to the depth of the target. Ferromagnetic cores improve electrical efficiency for targeting superficial brain areas; however magnetic saturation reduces the effectiveness of the core for deeper targets, especially for highly focal coils. Distancing winding segments from the head, as in the H1 coil, increases the required stimulation energy. Conclusions Among standard commercial coils, the double cone coil offers high energy efficiency and balance between stimulated volume and superficial field strength. Direct TMS of targets at depths of ~ 4 cm or more results in superficial stimulation strength that exceeds the upper limit in current rTMS safety guidelines. Approaching depths of ~ 6 cm is almost certainly unsafe considering the excessive superficial stimulation strength and activated brain volume. Significance Coil design limitations and tradeoffs are important for rational and safe exploration of dTMS. PMID:24411523

  2. Transcranial magnetic stimulation: Improved coil design for deep brain investigation

    NASA Astrophysics Data System (ADS)

    Crowther, L. J.; Marketos, P.; Williams, P. I.; Melikhov, Y.; Jiles, D. C.; Starzewski, J. H.

    2011-04-01

    This paper reports on a design for a coil for transcranial magnetic stimulation. The design shows potential for improving the penetration depth of the magnetic field, allowing stimulation of subcortical structures within the brain. The magnetic and induced electric fields in the human head have been calculated with finite element electromagnetic modeling software and compared with empirical measurements. Results show that the coil design used gives improved penetration depth, but also indicates the likelihood of stimulation of additional tissue resulting from the spatial distribution of the magnetic field.

  3. Deep transcranial magnetic stimulation as a treatment for psychiatric disorders: a comprehensive review.

    PubMed

    Bersani, F S; Minichino, A; Enticott, P G; Mazzarini, L; Khan, N; Antonacci, G; Raccah, R N; Salviati, M; Delle Chiaie, R; Bersani, G; Fitzgerald, P B; Biondi, M

    2013-01-01

    Deep transcranial magnetic stimulation (TMS) is a technique of neuromodulation and neurostimulation based on the principle of electromagnetic induction of an electric field in the brain. The coil (H-coil) used in deep TMS is able to modulate cortical excitability up to a maximum depth of 6 cm and is therefore able not only to modulate the activity of the cerebral cortex but also the activity of deeper neural circuits. Deep TMS is largely used for the treatment of drug-resistant major depressive disorder (MDD) and is being tested to treat a very wide range of neurological, psychiatric and medical conditions. The aim of this review is to illustrate the biophysical principles of deep TMS, to explain the pathophysiological basis for its utilization in each psychiatric disorder (major depression, autism, bipolar depression, auditory hallucinations, negative symptoms of schizophrenia), to summarize the results presented thus far in the international scientific literature regarding the use of deep TMS in psychiatry, its side effects and its effects on cognitive functions. PMID:22559998

  4. Brief Communications transcranial magnetic

    E-print Network

    Litt, Brian

    Brief Communications Repetitive transcranial magnetic stimulation does not replicate the Wada test magnetic stimulation (rTMS) with bilateral Wada tests in 17 epilepsy surgery candidates. Although rTMS lateralization corre- lated with the Wada test in most subjects, rTMS also favored the right hemisphere at a rate

  5. 21 CFR 882.5805 - Repetitive transcranial magnetic stimulation system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...5805 Repetitive transcranial magnetic stimulation system. (a) Identification. A repetitive transcranial magnetic stimulation system is an external...delivers transcranial repetitive pulsed magnetic fields of sufficient magnitude...

  6. 21 CFR 882.5805 - Repetitive transcranial magnetic stimulation system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...5805 Repetitive transcranial magnetic stimulation system. (a) Identification. A repetitive transcranial magnetic stimulation system is an external...delivers transcranial repetitive pulsed magnetic fields of sufficient magnitude...

  7. 21 CFR 882.5805 - Repetitive transcranial magnetic stimulation system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...5805 Repetitive transcranial magnetic stimulation system. (a) Identification. A repetitive transcranial magnetic stimulation system is an external...delivers transcranial repetitive pulsed magnetic fields of sufficient magnitude...

  8. Deep transcranial magnetic stimulation add-on for the treatment of auditory hallucinations: a double-blind study

    PubMed Central

    2012-01-01

    Background About 25% of schizophrenia patients with auditory hallucinations are refractory to pharmacotherapy and electroconvulsive therapy. We conducted a deep transcranial magnetic stimulation (TMS) pilot study in order to evaluate the potential clinical benefit of repeated left temporoparietal cortex stimulation in these patients. The results were encouraging, but a sham-controlled study was needed to rule out a placebo effect. Methods A total of 18 schizophrenic patients with refractory auditory hallucinations were recruited, from Beer Yaakov MHC and other hospitals outpatient populations. Patients received 10 daily treatment sessions with low-frequency (1 Hz for 10 min) deep TMS applied over the left temporoparietal cortex, using the H1 coil at the intensity of 110% of the motor threshold. Procedure was either real or sham according to patient randomization. Patients were evaluated via the Auditory Hallucinations Rating Scale, Scale for the Assessment of Positive Symptoms-Negative Symptoms, Clinical Global Impressions, and Quality of Life Questionnaire. Results In all, 10 patients completed the treatment (10 TMS sessions). Auditory hallucination scores of both groups improved; however, there was no statistical difference in any of the scales between the active and the sham treated groups. Conclusions Low-frequency deep TMS to the left temporoparietal cortex using the protocol mentioned above has no statistically significant effect on auditory hallucinations or the other clinical scales measured in schizophrenic patients. Trial Registration Clinicaltrials.gov identifier: NCT00564096. PMID:22559192

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

    PubMed Central

    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

    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

  10. Efficacy of Add-On Deep Transcranial Magnetic Stimulation in Comorbid Alcohol Dependence and Dysthymic Disorder: Three Case Reports

    PubMed Central

    Rapinesi, Chiara; Serata, Daniele; Casale, Antonio Del; Bersani, Francesco S.; Solfanelli, Andrea; Scatena, Paola; Raccah, Ruggero N.; Brugnoli, Roberto; Digiacomantonio, Vittorio; Carbonetti, Paolo; Fensore, Claudio; Tatarelli, Roberto; Angeletti, Gloria; Ferracuti, Stefano; Girardi, Paolo

    2013-01-01

    Background: Craving for alcohol is associated with abnormal activation in the dorsolateral prefrontal cortex. Deep transcranial magnetic stimulation (dTMS) has shown promise in the treatment of depression. There are few treatment options for treatment-resistant dysthymic disorder comorbid with alcohol use disorder. Objective: To investigate the possible anticraving efficacy of bilateral dorsolateral prefrontal cortex high-frequency dTMS in 3 patients with comorbid long-term DSM-IV-TR dysthymic disorder and alcohol use disorder. Method: Three patients with alcohol use disorder with dysthymic disorder in their detoxification phase (abstaining for > 1 month) underwent twenty 20-minute sessions of 20 Hz dTMS over the dorsolateral prefrontal cortex over 28 days between 2011 and 2012. Alcohol craving was rated with the Obsessive Compulsive Drinking Scale and depressive symptoms with the Hamilton Depression Rating Scale. Results: All 3 patients responded unsatisfactorily to initial intravenous antidepressant and antianxiety combinations but responded after 10 dTMS sessions, improving on both anxiety-depressive symptoms and craving. This improvement enabled us to reduce antidepressant dosages after dTMS cycle completion. Discussion: High-frequency bilateral dorsolateral prefrontal cortex dTMS with left prevalence was found to produce significant anticraving effects in alcohol use disorder comorbid with dysthymic disorder. The potential of dTMS for reducing craving in patients with substance use disorder deserves to be further investigated. PMID:23724355

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

    PubMed Central

    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

    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

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

    PubMed

    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

    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

  13. Transcranial magnetic stimulation in neurology

    PubMed Central

    Eldaief, Mark C.; Press, Daniel Z.

    2013-01-01

    Summary Transcranial magnetic stimulation (TMS) is a neurophysiologic technique to noninvasively induce a controlled current pulse in a prespecified cortical target. This can be used to transiently disrupt the function of the targeted cortical region and explore causal relations to behavior, assess cortical reactivity, and map out functionally relevant brain regions, for example during presurgical assessments. Particularly when applied repetitively, TMS can modify cortical excitability and the effects can propagate trans-synaptically to interconnected cortical, subcortical, and spinal cord regions. As such, TMS can be used to assess the functional integrity of neural circuits and to modulate brain activity with potential therapeutic intent. PMID:24353923

  14. Side effects of repetitive transcranial magnetic stimulation.

    PubMed

    Wassermann, E M

    2000-01-01

    The side effects of repetitive transcranial magnetic stimulation are largely unexplored and the limits of safe exposure have not been determined except as regards the acute production of seizures. Although tissue damage is unlikely, however, cognitive and other adverse effects have been observed and the possibility of unintended long-term changes in brain function are theoretically possible. PMID:11126186

  15. Transcranial Magnetic Stimulation Intensities in Cognitive Paradigms

    Microsoft Academic Search

    Jakob A. Kaminski; Franziska M. Korb; Arno Villringer; Derek V. M. Ott; Joseph Najbauer

    2011-01-01

    BackgroundTranscranial magnetic stimulation (TMS) has become an important experimental tool for exploring the brain's functional anatomy. As TMS interferes with neural activity, the hypothetical function of the stimulated area can thus be tested. One unresolved methodological issue in TMS experiments is the question of how to adequately calibrate stimulation intensities. The motor threshold (MT) is often taken as a reference

  16. The effects of transcranial magnetic stimulation on visual rivalry

    E-print Network

    Tadin, Duje

    observers. We performed an analogous set of experiments by replacing TMS with transient visual stimulation of transcranial magnetic stimulation on visual rivalry. Journal of Vision, 7(7):2, 1­11, httpThe effects of transcranial magnetic stimulation on visual rivalry Vanderbilt Vision Research

  17. Transcranial magnetic stimulation in cognitive rehabilitation.

    PubMed

    Miniussi, Carlo; Rossini, Paolo Maria

    2011-10-01

    Repetitive transcranial magnetic stimulation (rTMS) can generate an increase or a decrease of neuronal excitability, which can modulate cognition and behaviour. Transcranial magnetic stimulation-induced cortical changes have been shown to result in neural plasticity. Thus, TMS provides an important opportunity to gain more insight into the mechanisms responsible for the remarkable flexibility of the central nervous system. The aim of this review was to cover the topics that could be useful when using TMS in the cognitive rehabilitation field after brain damage. The basic TMS principles are introduced, together with the clinical application for diagnosis and prognosis, the biological aspects, and the use in cognitive neuroscience studies. Finally, several hypotheses are discussed to explain the likely mechanisms induced by TMS that favour the recovery of a function after brain damage and cause the adult brain to undergo plasticity. The possibility of non-invasively interacting with the functioning of the brain and its plasticity mechanisms - a possibility that may eventually lead to cognitive and behavioural modifications - opens new and exciting scenarios in the cognitive neurorehabilitation field. PMID:21462081

  18. [Transcranial magnetic stimulation in cognition and neuropsychology].

    PubMed

    Verdon, C-M; Saba, G; Januel, D

    2004-01-01

    Classical neuropsychology relies on patients with irreversible brain lesions and cognitive impairments give informations about normal brain function. Transcranial Magnetic Stimulation (TMS) is a non-invasive method which involves placing an electromagnetic coil on the scalp. A pulse generates a magnetic field and this one passes, unattenuated by the skin and scalp, into the cortex inducing a current which results in neural activity. The technique shows a good temporal resolution and, moreover, because it represents an interference technique, can be said to have excellent functional resolution. For this reason, TMS appears to be a new tool for research in neuropsychology, producing transitory 'virtual lesion'effects which could help to understand how, when and where cognitive tasks are performed. The purpose of this article is to review recent research using TMS in cognition and neuropsychology, in a non exhaustive way. In safety studies, single TMS over motor cortex can produce simple movements. Several groups have applied TMS to the study of visual processing and found an impaired detection of visual stimuli. In a same way, TMS can disrupt speech when it was delivered in the language dominant hemisphere. Studies on the memory effects of TMS have been conflicting and the results seem to depend on the choice of paradigm and parameters. Other study depicted improvements in executive functioning after TMS on the left middle frontal gyrus or a diminution in reaction time during an analogic reasoning task. Moreover, some facial emotions seem to be less recognizable after TMS. Although TMS seem to be a new tool for neuro-psychological investigations in healthy subjects, few studies reported cognitive effects of rTMS treatment in psychiatry. In a therapeutic view, many of these trials have supported a significant effect of TMS, but in some studies the effect is small and short lived. Several groups have reported on the use of rTMS as a treatment in resistant major depression and the impact on cognition functioning. Most of results tend to find no adverse cognitive effects after several weeks of daily rTMS in depressed patients, compared to Electroconvulsivo-therapy (ECT). The effects of transcranial magnetic stimulation (TMS) on hallucination severity and neurocognition were studied in a recent study. A statistically significant improvement was observed on a hallucination scale and on one cognitive measure. TMS is a promising tool for cognitive neuroscience and can provide complementary information to the one obtained using neuropsychological tests, and the one obtained using functional imaging techniques, which have superior spatial but inferior temporal resolution. PMID:15538312

  19. Numerical dosimetry of transcranial magnetic stimulation coils

    NASA Astrophysics Data System (ADS)

    Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2014-03-01

    Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique capable of stimulating neurons by means of electromagnetic induction. TMS can be used to map brain function and shows promise for the diagnosis and treatment of neurological and psychiatric disorders. Calculation of fields induced in the brain are necessary to accurately identify stimulated neural tissue during TMS. This allows the development of novel TMS coil designs capable of stimulating deeper brain regions and increasing the localization of stimulation that can be achieved. We have performed numerical calculations of magnetic and electric field with high-resolution anatomically realistic human head models to find these stimulated brain regions for a variety of proposed TMS coil designs. The realistic head models contain heterogeneous tissue structures and electrical conductivities, yielding superior results to those obtained from the simplified homogeneous head models that are commonly employed. The attenuation of electric field as a function of depth in the brain and the localization of stimulating field have been methodically investigated. In addition to providing a quantitative comparison of different TMS coil designs the variation of induced field between subjects has been investigated. We also show the differences in induced fields between adult, adolescent and child head models to preemptively identify potential safety issues in the application of pediatric TMS.

  20. Repetitive transcranial magnetic stimulation and drug addiction.

    PubMed

    Barr, Mera S; Farzan, Faranak; Wing, Victoria C; George, Tony P; Fitzgerald, Paul B; Daskalakis, Zafiris J

    2011-10-01

    Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that is now being tested for its ability to treat addiction. This review discusses current research approaches and results of studies which measured the therapeutic use of rTMS to treat tobacco, alcohol and illicit drug addiction. The research in this area is limited and therefore all studies evaluating the therapeutic use of rTMS in tobacco, alcohol or illicit drug addiction were retained including case studies through NCBI PubMed ( http://www.ncbi.nlm.nih.gov ) and manual searches. A total of eight studies were identified that examined the ability of rTMS to treat tobacco, alcohol and cocaine addiction. The results of this review indicate that rTMS is effective in reducing the level of cravings for smoking, alcohol, and cocaine when applied at high frequencies to the dorsolateral prefrontal cortex (DLPFC). Furthermore, these studies suggest that repeated sessions of high frequency rTMS over the DLPFC may be most effective in reducing the level of smoking and alcohol consumption. Although work in this area is limited, this review indicates that rTMS is a promising modality for treating drug addiction. PMID:22200135

  1. Combining functional magnetic resonance imaging with transcranial electrical stimulation

    PubMed Central

    Saiote, Catarina; Turi, Zsolt; Paulus, Walter; Antal, Andrea

    2013-01-01

    Transcranial electrical stimulation (tES) is a neuromodulatory method with promising potential for basic research and as a therapeutic tool. The most explored type of tES is transcranial direct current stimulation (tDCS), but also transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) have been shown to affect cortical excitability, behavioral performance and brain activity. Although providing indirect measure of brain activity, functional magnetic resonance imaging (fMRI) can tell us more about the global effects of stimulation in the whole brain and what is more, on how it modulates functional interactions between brain regions, complementing what is known from electrophysiological methods such as measurement of motor evoked potentials. With this review, we aim to present the studies that have combined these techniques, the current approaches and discuss the results obtained so far. PMID:23935578

  2. Transcranial magnetic stimulation in ALS Utility of central motor conduction tests

    E-print Network

    Pullman, Seth L.

    Transcranial magnetic stimulation in ALS Utility of central motor conduction tests A.G. Floyd, BA Q transcranial magnetic stimulation; UMN upper motor neuron. ALS is diagnosed by finding clinical upper motor. Mitsumoto, MD S.L. Pullman, MD ABSTRACT Objective: To investigate transcranial magnetic stimulation (TMS

  3. INVITED REVIEW Safety of Theta Burst Transcranial Magnetic Stimulation

    E-print Network

    Walker, Matthew P.

    of electromagnetic induction, whereby a strong, rapidly fluctuating magnetic field pulse (produced by the TMS coil in the human brain through repetitive transcranial magnetic stimulation. TBS involves applying short trains stimulation (TMS) can be used to experi- mentally manipulate brain activity and is capable of inducing long

  4. Non invasive brain stimulation : modeling and experimental analysis of transcranial magnetic stimulations and transcranial DC stimulation as a modality for neuropathology treatment

    E-print Network

    Wagner, Timothy A. (Timothy Andrew), 1974-

    2006-01-01

    This thesis will explore the use of Transcranial Magnetic Stimulation (TMS) and Transcranial DC Stimulation (tDCS) as modalities for neuropathology treatment by means of both experimental and modeling paradigms. The first ...

  5. Modulation of cortical oscillatory activity during transcranial magnetic stimulation

    Microsoft Academic Search

    Debora Brignani; Paolo Manganotti; Paolo M. Rossini; Carlo Miniussi

    2008-01-01

    Transcranial magnetic stimulation (TMS) can transiently modulate cortical excitability, with a net effect depending on the stimulation frequency (? 1 Hz inhibition vs. ? 5 Hz facilitation, at least for the motor cortex). This possibility has generated interest in experiments aiming to improve deficits in clinical settings, as well as deficits in the cognitive domain. The aim of the present

  6. Transcranial magnetic stimulation for the treatment of major depression

    PubMed Central

    Janicak, Philip G; Dokucu, Mehmet E

    2015-01-01

    Major depression is often difficult to diagnose accurately. Even when the diagnosis is properly made, standard treatment approaches (eg, psychotherapy, medications, or their combination) are often inadequate to control acute symptoms or maintain initial benefit. Additional obstacles involve safety and tolerability problems, which frequently preclude an adequate course of treatment. This leaves an important gap in our ability to properly manage major depression in a substantial proportion of patients, leaving them vulnerable to ensuing complications (eg, employment-related disability, increased risk of suicide, comorbid medical disorders, and substance abuse). Thus, there is a need for more effective and better tolerated approaches. Transcranial magnetic stimulation is a neuromodulation technique increasingly used to partly fill this therapeutic void. In the context of treating depression, we critically review the development of transcranial magnetic stimulation, focusing on the results of controlled and pragmatic trials for depression, which consider its efficacy, safety, and tolerability. PMID:26170668

  7. Modulation of corticospinal excitability by repetitive transcranial magnetic stimulation

    Microsoft Academic Search

    Fumiko Maeda; Julian Paul Keenan; Jose Maria Tormos; Helge Topka; Alvaro Pascual-Leone

    2000-01-01

    Objective: Repetitive transcranial magnetic stimulation (rTMS) is able to modulate the corticospinal excitability and the effects appear to last beyond the duration of the rTMS itself. Different studies, employing different rTMS parameters, report different modulation of corticospinal excitability ranging from inhibition to facilitation. Intraindividual variability of these effects and their reproducibility are unclear.Methods: We examined the modulatory effects of rTMS

  8. Modulation of corticospinal excitability by repetitive transcranial magnetic stimulation

    Microsoft Academic Search

    Fumiko Maeda; Julian Paul Keenan; Jose Maria Tormos; Helge Topka; Alvaro Pascual-leone

    Abstract Objective: Repetitive transcranial magnetic stimulation (rTMS) is able to modulate the corticospinal excitability and the effects appear to last beyond the duration of the rTMS itself. Different studies, employing different rTMS parameters, report different modulation of corticospinal excitability ranging from inhibition to facilitation. Intraindividual variability of these effects and their reproducibility are unclear. Methods: We examined the modulatory effects

  9. Transcranial magnetic stimulation in the treatment of psychiatric disorders

    Microsoft Academic Search

    Deborah R. Kim; Angeliki Pesiridou; John P. O’Reardon

    2009-01-01

    Transcranial magnetic stimulation (TMS) is an emerging novel treatment modality for psychiatric disorders, particularly major\\u000a depression. A device for delivery of TMS was approved by the US Food and Drug Administration for treatment of major depressive\\u000a disorder in adults. TMS is being studied for a variety of psychiatric disorders, including obsessivecompulsive disorder, post-traumatic\\u000a stress disorder, and auditory hallucinations in schizophrenia.

  10. Brain-Behavior Relations: Transcranial Magnetic Stimulation: A Review

    Microsoft Academic Search

    PAOLO MARIA ROSSINI; L. Rosinni; FLORINDA FERRERI

    2010-01-01

    This paper reviewed the transcranial magnetic stimulation (TMS) applications for brain-behavior relations. Along with rapid-rate TMS, coils designed for focal stimulation and image-guided targeting of stimulation to desired cortical structures, neuronal processes can now be disrupted even in relatively well-defined cortical areas. Delivering two sequential pulses to the primary motor cortex(MI) allowed the exploration of inhibition and facilitation within the

  11. Improved executive functioning following repetitive transcranial magnetic stimulation.

    PubMed

    Moser, D J; Jorge, R E; Manes, F; Paradiso, S; Benjamin, M L; Robinson, R G

    2002-04-23

    The cognitive effects of active and sham repetitive transcranial magnetic stimulation (rTMS) were examined in 19 middle-aged and elderly patients with refractory depression. Patients received either active (n = 9) or sham (n = 10) rTMS targeted at the anterior portion of the left middle frontal gyrus. Patients in the active rTMS group improved significantly on a test of cognitive flexibility and conceptual tracking (Trail Making Test-B). PMID:11971103

  12. Transcranial magnetic stimulation over dorsolateral prefrontal cortex in Parkinson's disease

    Microsoft Academic Search

    Miguel Fernandez del Olmo; Olalla Bello; Javier Cudeiro

    2006-01-01

    Objective: Several studies have shown that repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) is effective in the treatment of depression in patients with Parkinson disease (PD). However, since research into the effect of this type of rTMS regime on motor function is limited, we studied the effect of rTMS over the DLPFC on the motor functions

  13. Role of Sustained Excitability of the Leg Motor Cortex After Transcranial Magnetic Stimulation in Associative Plasticity

    E-print Network

    Gorassini, Monica

    Role of Sustained Excitability of the Leg Motor Cortex After Transcranial Magnetic Stimulation of the leg motor cortex after transcranial magnetic stimulation in asso- ciative plasticity. J Neurophysiol magnetic stimulation (TMS) produces specific changes to the motor-evoked potentials (MEPs) in lower leg

  14. Transcranial static magnetic field stimulation of the human motor cortex.

    PubMed

    Oliviero, Antonio; Mordillo-Mateos, Laura; Arias, Pablo; Panyavin, Ivan; Foffani, Guglielmo; Aguilar, Juan

    2011-10-15

    The aim of the present study was to investigate in healthy humans the possibility of a non-invasive modulation of motor cortex excitability by the application of static magnetic fields through the scalp. Static magnetic fields were obtained by using cylindrical NdFeB magnets. We performed four sets of experiments. In Experiment 1, we recorded motor potentials evoked by single-pulse transcranial magnetic stimulation (TMS) of the motor cortex before and after 10 min of transcranial static magnetic field stimulation (tSMS) in conscious subjects. We observed an average reduction of motor cortex excitability of up to 25%, as revealed by TMS, which lasted for several minutes after the end of tSMS, and was dose dependent (intensity of the magnetic field) but not polarity dependent. In Experiment 2, we confirmed the reduction of motor cortex excitability induced by tSMS using a double-blind sham-controlled design. In Experiment 3, we investigated the duration of tSMS that was necessary to modulate motor cortex excitability. We found that 10 min of tSMS (compared to 1 min and 5 min) were necessary to induce significant effects. In Experiment 4, we used transcranial electric stimulation (TES) to establish that the tSMS-induced reduction of motor cortex excitability was not due to corticospinal axon and/or spinal excitability, but specifically involved intracortical networks. These results suggest that tSMS using small static magnets may be a promising tool to modulate cerebral excitability in a non-invasive, painless, and reversible way. PMID:21807616

  15. Cortical excitability and sleep deprivation: a transcranial magnetic stimulation study

    PubMed Central

    Civardi, C; Boccagni, C; Vicentini, R; Bolamperti, L; Tarletti, R; Varrasi, C; Monaco, F; Cantello, R

    2001-01-01

    The objective was to assess the changes in cortical excitability after sleep deprivation in normal subjects. Sleep deprivation activates EEG epileptiform activity in an unknown way. Transcranial magnetic stimulation (TMS) can inform on the excitability of the primary motor cortex. Eight healthy subjects (four men and four women) were studied. Transcranial magnetic stimulation (single and paired) was performed by a focal coil over the primary motor cortex, at the "hot spot" for the right first dorsal interosseous muscle. The following motor evoked potential features were measured: (a) active and resting threshold to stimulation; (b) duration of the silent period; (c) amount of intracortical inhibition on paired TMS at the interstimulus intervals of 2 and 3 ms and amount of facilitation at interstimulus intervals of 14 and 16 ms. The whole TMS session was repeated after a sleep deprivation of at least 24 hours. After the sleep deprivation, the threshold to stimulation (in the active and resting muscle), as well as the silent period, did not change significantly. By contrast, the paired stimulus study showed a significant (p<0.05) reduction in both intracortical inhibition and facilitation. Thus, TMS showed that sleep deprivation is associated with changes in inhibition-facilitation balance in the primary motor cortex of normal subjects. These changes might have a link with the background factors of the "activating" effects of sleep deprivation.?? PMID:11723210

  16. Transcranial Magnetic Stimulation in a Finger-tapping Task Separates Motor from Timing

    E-print Network

    Moses, Elisha

    Transcranial Magnetic Stimulation in a Finger- tapping Task Separates Motor from Timing Mechanisms,3 , and Elisha Moses1 Abstract & We study the interplay between motor programs and their timing in the brain by using precise pulses of transcranial mag- netic stimulation (TMS) applied to the primary motor cortex

  17. The study of deep brain structures by transcranial duplex sonography and imaging resonance correlation.

    PubMed

    Sahuquillo, Patricia; Tembl, Jose Ignacio; Parkhutik, Vera; Vázquez, Juan Francisco; Sastre, Isabel; Lago, Aida

    2013-02-01

    Transcranial duplex sonography (TCS) currently provides us with images of deep brain structures with sufficient resolution. We chose 2 sonographic quantitative parameters: the diameter of the third ventricle and a measurement not used by TCS to date, the midbrain area. Their reliability and reproducibility were assessed using magnetic resonance imaging (MRI) as the reference. A total of 99 patients free from neurodegenerative disorders were examined using TCS, and both parameters were measured by 2 independent explorers. Measurements of third-ventricle diameter by TCS showed very good correlation (r = 0.80) and agreement (ICC = 0.89) with measurements obtained by MRI. Measurements of the midbrain area by TCS also provided acceptable values with moderate correlation (r = 0.36) and agreement (ICC = 0.53). Interexplorer correlation values were good (ICC = 0.98 and 0.79 for the third ventricle and midbrain areas, respectively). Further studies will be required to determine the potential diagnostic usefulness of these parameters. PMID:23257352

  18. [Newer treatment of epilepsy--brain pacemakers and transcranial magnetic stimulation].

    PubMed

    Akamatsu, Naoki

    2005-11-01

    The antiepileptic medication and surgical treatment had brought many patients with epilepsy to be seizure free, however, one third of the patients continue to experience seizures. There has recently been an explosion of research into brain stimulation for treating these intractable epilepsy patients. This is largely due to the success of deep brain stimulation of movement disorders. The intelligent cardiac pacemakers also stimulated the neurosurgeons to utilize the implantable devices. In this paper, brain stimulations with vagus nerve stimulator (VNS), depth electrodes, subdural electrodes, external responsive neuro-stimulator, implantable brain stimulator and transcranial magnetic stimulator are reviewed. The VNS had been approved in Europe and United States for clinical use. The efficacy of the VNS has already proven by the controlled trials. Stimulation of the thalamus, subthalamic nucleus and hippocampus showed some efficacy in a small number of patients, however, large scale traials remains to be undertaken. External responsive neurostimulator has shown efficacy and safety to justify further studies with implantable brain stimulators. The multi-center cooperative study is ongoing in the US to examine the usefulness of the implantable stimulator. Animal studies showed efficacy of the transcranial magnetic stimulation for the treatment and prevention of the seizures and status epilepticus. PMID:16447765

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

    Microsoft Academic Search

    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

    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

  20. Possible Mechanisms Underlying the Therapeutic Effects of Transcranial Magnetic Stimulation.

    PubMed

    Chervyakov, Alexander V; Chernyavsky, Andrey Yu; Sinitsyn, Dmitry O; Piradov, Michael A

    2015-01-01

    Transcranial magnetic stimulation (TMS) is an effective method used to diagnose and treat many neurological disorders. Although repetitive TMS (rTMS) has been used to treat a variety of serious pathological conditions including stroke, depression, Parkinson's disease, epilepsy, pain, and migraines, the pathophysiological mechanisms underlying the effects of long-term TMS remain unclear. In the present review, the effects of rTMS on neurotransmitters and synaptic plasticity are described, including the classic interpretations of TMS effects on synaptic plasticity via long-term potentiation and long-term depression. We also discuss the effects of rTMS on the genetic apparatus of neurons, glial cells, and the prevention of neuronal death. The neurotrophic effects of rTMS on dendritic growth and sprouting and neurotrophic factors are described, including change in brain-derived neurotrophic factor concentration under the influence of rTMS. Also, non-classical effects of TMS related to biophysical effects of magnetic fields are described, including the quantum effects, the magnetic spin effects, genetic magnetoreception, the macromolecular effects of TMS, and the electromagnetic theory of consciousness. Finally, we discuss possible interpretations of TMS effects according to dynamical systems theory. Evidence suggests that a rTMS-induced magnetic field should be considered a separate physical factor that can be impactful at the subatomic level and that rTMS is capable of significantly altering the reactivity of molecules (radicals). It is thought that these factors underlie the therapeutic benefits of therapy with TMS. Future research on these mechanisms will be instrumental to the development of more powerful and reliable TMS treatment protocols. PMID:26136672

  1. Possible Mechanisms Underlying the Therapeutic Effects of Transcranial Magnetic Stimulation

    PubMed Central

    Chervyakov, Alexander V.; Chernyavsky, Andrey Yu.; Sinitsyn, Dmitry O.; Piradov, Michael A.

    2015-01-01

    Transcranial magnetic stimulation (TMS) is an effective method used to diagnose and treat many neurological disorders. Although repetitive TMS (rTMS) has been used to treat a variety of serious pathological conditions including stroke, depression, Parkinson’s disease, epilepsy, pain, and migraines, the pathophysiological mechanisms underlying the effects of long-term TMS remain unclear. In the present review, the effects of rTMS on neurotransmitters and synaptic plasticity are described, including the classic interpretations of TMS effects on synaptic plasticity via long-term potentiation and long-term depression. We also discuss the effects of rTMS on the genetic apparatus of neurons, glial cells, and the prevention of neuronal death. The neurotrophic effects of rTMS on dendritic growth and sprouting and neurotrophic factors are described, including change in brain-derived neurotrophic factor concentration under the influence of rTMS. Also, non-classical effects of TMS related to biophysical effects of magnetic fields are described, including the quantum effects, the magnetic spin effects, genetic magnetoreception, the macromolecular effects of TMS, and the electromagnetic theory of consciousness. Finally, we discuss possible interpretations of TMS effects according to dynamical systems theory. Evidence suggests that a rTMS-induced magnetic field should be considered a separate physical factor that can be impactful at the subatomic level and that rTMS is capable of significantly altering the reactivity of molecules (radicals). It is thought that these factors underlie the therapeutic benefits of therapy with TMS. Future research on these mechanisms will be instrumental to the development of more powerful and reliable TMS treatment protocols. PMID:26136672

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

    PubMed Central

    George, Mark S; Aston-Jones, Gary

    2010-01-01

    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 transcranial direct current stimulation. Two of these approaches have FDA approval as therapies. PMID:19693003

  3. Deep Brain Stimulation using Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Jiles, David; Williams, Paul; Crowther, Lawrence; Iowa State University Team; Wolfson Centre For Magnetics Team

    2011-03-01

    New applications for transcranial magnetic stimulation are developing rapidly for both diagnostic and therapeutic purposes. Therefore so is the demand for improved performance, particularly in terms of their ability to stimulate deeper regions of the brain and to do so selectively. The coil designs that are used presently are limited in their ability to stimulate the brain at depth and with high spatial focality. Consequently, any improvement in coil performance would have a significant impact in extending the usefulness of TMS in both clinical applications and academic research studies. New and improved coil designs have then been developed, modeled and tested as a result of this work. A large magnetizing coil, 300mm in diameter and compatible with a commercial TMS system has been constructed to determine its feasibility for use as a deep brain stimulator. The results of this work have suggested directions that could be pursued in order to further improve the coil designs.

  4. Modulating functional and dysfunctional mentalizing by transcranial magnetic stimulation

    PubMed Central

    Schuwerk, Tobias; Langguth, Berthold; Sommer, Monika

    2014-01-01

    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

  5. Measurement of evoked electroencephalography induced by transcranial magnetic stimulation

    NASA Astrophysics Data System (ADS)

    Iramina, Keiji; Maeno, Takashi; Nonaka, Yukio; Ueno, Shoogo

    2003-05-01

    This study focused on the measurement of evoked potentials induced by transcranial magnetic stimulation (TMS) for observing the neuronal connectivity in the brain. We developed an electroencephalography (EEG) measurement system to eliminate the electromagnetic interaction emitted from TMS. EEG activities 5 ms after TMS stimulation were measured. Using this artifact free amplifier, we investigated the intensity dependence of brain activation induced by TMS. When the stimulus intensity was changed at three levels, TMS-evoked EEG responses were measured. Several components of the evoked potential appeared at 9 ms, 20 ms, and 50 ms after stimulation. A large response appeared at about 9 ms after cerebellar TMS. There was a significant dependence of these responses on the stimulus intensity. During right-hand side motor area stimulation, there was no clear peak of the wave forms within 10 ms latency. Occipital stimulation caused more evoked responses to spread to the center of the brain than at other areas of stimulation. The evoked signal by TMS was possibly conducted posteriorly to anteriorly along the pathways of the neuronal fiber exiting the cerebellum into the cerebral cortex.

  6. Electronically switchable sham transcranial magnetic stimulation (TMS) system.

    PubMed

    Hoeft, Fumiko; Wu, Daw-An; Hernandez, Arvel; Glover, Gary H; Shimojo, Shinsuke

    2008-01-01

    Transcranial magnetic stimulation (TMS) is increasingly being used to demonstrate the causal links between brain and behavior in humans. Further, extensive clinical trials are being conducted to investigate the therapeutic role of TMS in disorders such as depression. Because TMS causes strong peripheral effects such as auditory clicks and muscle twitches, experimental artifacts such as subject bias and placebo effect are clear concerns. Several sham TMS methods have been developed, but none of the techniques allows one to intermix real and sham TMS on a trial-by-trial basis in a double-blind manner. We have developed an attachment that allows fast, automated switching between Standard TMS and two types of control TMS (Sham and Reverse) without movement of the coil or reconfiguration of the setup. We validate the setup by performing mathematical modeling, search-coil and physiological measurements. To see if the stimulus conditions can be blinded, we conduct perceptual discrimination and sensory perception studies. We verify that the physical properties of the stimulus are appropriate, and that successive stimuli do not contaminate each other. We find that the threshold for motor activation is significantly higher for Reversed than for Standard stimulation, and that Sham stimulation entirely fails to activate muscle potentials. Subjects and experimenters perform poorly at discriminating between Sham and Standard TMS with a figure-of-eight coil, and between Reverse and Standard TMS with a circular coil. Our results raise the possibility of utilizing this technique for a wide range of applications. PMID:18398456

  7. Modulating functional and dysfunctional mentalizing by transcranial magnetic stimulation.

    PubMed

    Schuwerk, Tobias; Langguth, Berthold; Sommer, Monika

    2014-01-01

    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

  8. Transcranial magnetic stimulation for geriatric depression: Promises and pitfalls

    PubMed Central

    Sabesan, Priyadharshini; Lankappa, Sudheer; Khalifa, Najat; Krishnan, Vasudevan; Gandhi, Rahul; Palaniyappan, Lena

    2015-01-01

    As the global population gets older, depression in the elderly is emerging as an important health issue. A major challenge in treating geriatric depression is the lack of robust efficacy for many treatments that are of significant benefit to depressed working age adults. Repetitive transcranial magnetic stimulation (rTMS) is a novel physical treatment approach used mostly in working age adults with depression. Many TMS trials and clinics continue to exclude the elderly from treatment citing lack of evidence in this age group. In this review, we appraise the evidence regarding the safety and efficacy of rTMS in the elderly. A consistent observation supporting a high degree of tolerability and safety among the elderly patients emerged across the Randomised Controlled Trials and the uncontrolled trials. Further, there is no reliable evidence negating the utility of rTMS in the elderly with depression. We also identified several factors other than age that moderate the observed variations in the efficacy of rTMS in the elderly. These factors include but not limited to: (1) brain atrophy; (2) intensity and number of pulses (dose-response relationship); and (3) clinical profile of patients. On the basis of the current evidence, the practice of excluding elderly patients from TMS clinics and trials cannot be supported. PMID:26110119

  9. Transcranial magnetic stimulation for treating depression in elderly patients

    PubMed Central

    Sayar, Gokben Hizli; Ozten, Eylem; Tan, Oguz; Tarhan, Nevzat

    2013-01-01

    Purpose The aim of the study reported here was to examine the safety and effectiveness of high-frequency repetitive transcranial magnetic stimulation (rTMS) in elderly patients with depression. Patients and methods Sixty-five depressed elderly patients received rTMS over their left prefrontal cortex for 6 days per week, from Monday to Saturday, for 3 weeks. The rTMS intensity was set at 100% of the motor threshold and 25 Hz stimulation with a duration of 2 seconds and was delivered 20 times at 30-second intervals. A full course comprised an average of 1000 magnetic pulses. Depression was rated using the Hamilton Depression Rating Scale (HAMD) before and after treatment. Response was defined as a 50% reduction in HAMD score. Patients with HAMD scores < 8 were considered to be in remission. Results The mean HAMD score for the study group decreased from 21.94 ± 5.12 before treatment to 11.28 ± 4.56 after rTMS (P < 0.001). Following the treatment period, 58.46% of the study group demonstrated significant mood improvement, as indexed by a reduction of more than 50% on the HAMD score. Nineteen of these 38 patients attained remission (HAMD score < 8), while 41.54% of all study patients achieved a partial response. None of the patients had a worsened HAMD score at the end of the treatment. Treatment was generally well tolerated and no serious adverse effects were reported. Conclusion In this study, rTMS was found to be a safe, well-tolerated treatment, and a useful adjunctive treatment to medications in elderly treatment-resistant depressed patients. This study contributes to the existing evidence on the antidepressant effect of rTMS in the treatment of depression in patients over 60 years of age. PMID:23723700

  10. Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

    PubMed Central

    Goss, David A.; Hoffman, Richard L.; Clark, Brian C.

    2012-01-01

    Transcranial magnetic stimulation (TMS) has been in use for more than 20 years 1, and has grown exponentially in popularity over the past decade. While the use of TMS has expanded to the study of many systems and processes during this time, the original application and perhaps one of the most common uses of TMS involves studying the physiology, plasticity and function of the human neuromuscular system. Single pulse TMS applied to the motor cortex excites pyramidal neurons transsynaptically 2 (Figure 1) and results in a measurable electromyographic response that can be used to study and evaluate the integrity and excitability of the corticospinal tract in humans 3. Additionally, recent advances in magnetic stimulation now allows for partitioning of cortical versus spinal excitability 4,5. For example, paired-pulse TMS can be used to assess intracortical facilitatory and inhibitory properties by combining a conditioning stimulus and a test stimulus at different interstimulus intervals 3,4,6-8. In this video article we will demonstrate the methodological and technical aspects of these techniques. Specifically, we will demonstrate single-pulse and paired-pulse TMS techniques as applied to the flexor carpi radialis (FCR) muscle as well as the erector spinae (ES) musculature. Our laboratory studies the FCR muscle as it is of interest to our research on the effects of wrist-hand cast immobilization on reduced muscle performance6,9, and we study the ES muscles due to these muscles clinical relevance as it relates to low back pain8. With this stated, we should note that TMS has been used to study many muscles of the hand, arm and legs, and should iterate that our demonstrations in the FCR and ES muscle groups are only selected examples of TMS being used to study the human neuromuscular system. PMID:22297466

  11. Study of the Electromagnetic Field of Transcranial Magnetic Stimulation Based on the Real Head Model

    Microsoft Academic Search

    Weizhong He; Peng Zhou; Dongdong Lin; Xin Zhao; MingShi Wang

    2009-01-01

    This paper presents the application of finite element method in analysis of the electromagnetic field within real head model exposed to a time varying magnetic field produced by the circuit-driving loop. To analyze the electromagnetic field under Transcranial Magnetic Stimulation precisely and display the stimulating effect of the loops in different geometrical forms, a 3-D real head model reconstructed from

  12. Repetitive Transcranial Magnetic Stimulation to the Primary Motor Cortex Interferes with

    E-print Network

    Jackson, Carl

    Repetitive Transcranial Magnetic Stimulation to the Primary Motor Cortex Interferes with Motor- cranial magnetic stimulation (rTMS) to test the idea that this ``motor learning by observing'' is based representations of novel motor skills can be ac- quired through visual observation. We used repetitive trans

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

    Microsoft Academic Search

    Beatriz Calvo Merino; Patrick Haggard

    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:

  14. Low-frequency transcranial magnetic stimulation is beneficial for enhancing synaptic plasticity in the aging brain

    PubMed Central

    Zhang, Zhan-chi; Luan, Feng; Xie, Chun-yan; Geng, Dan-dan; Wang, Yan-yong; Ma, Jun

    2015-01-01

    In the aging brain, cognitive function gradually declines and causes a progressive reduction in the structural and functional plasticity of the hippocampus. Transcranial magnetic stimulation is an emerging and novel neurological and psychiatric tool used to investigate the neurobiology of cognitive function. Recent studies have demonstrated that low-frequency transcranial magnetic stimulation (?1 Hz) ameliorates synaptic plasticity and spatial cognitive deficits in learning-impaired mice. However, the mechanisms by which this treatment improves these deficits during normal aging are still unknown. Therefore, the current study investigated the effects of transcranial magnetic stimulation on the brain-derived neurotrophic factor signal pathway, synaptic protein markers, and spatial memory behavior in the hippocampus of normal aged mice. The study also investigated the downstream regulator, Fyn kinase, and the downstream effectors, synaptophysin and growth-associated protein 43 (both synaptic markers), to determine the possible mechanisms by which transcranial magnetic stimulation regulates cognitive capacity. Transcranial magnetic stimulation with low intensity (110% average resting motor threshold intensity, 1 Hz) increased mRNA and protein levels of brain-derived neurotrophic factor, tropomyosin receptor kinase B, and Fyn in the hippocampus of aged mice. The treatment also upregulated the mRNA and protein expression of synaptophysin and growth-associated protein 43 in the hippocampus of these mice. In conclusion, brain-derived neurotrophic factor signaling may play an important role in sustaining and regulating structural synaptic plasticity induced by transcranial magnetic stimulation in the hippocampus of aging mice, and Fyn may be critical during this regulation. These responses may change the structural plasticity of the aging hippocampus, thereby improving cognitive function. PMID:26199608

  15. Efficacy of transcranial magnetic stimulation (TMS) in depression: naturalistic study.

    PubMed

    Aliño, Juan José López-Ibor; Jiménez, J L Pastrana; Flores, S Cisneros; Alcocer, M I López-Ibor

    2010-01-01

    Transcranial magnetic stimulation (TMS) is a technique is which the evidence has been confirming its efficacy. Repetitive stimulation (rTMS) of the left prefrontal dorsolateral (LPFDL) area with frequencies between 10 and 20 Hz has been shown to be effective in major depression. This article presents the prospective analysis of the treatments performed using TMS on LPFDL at 20 Hz with an intensity of 70% in a protocol of 10 sessions on 107 patients (41 male and 61 female) due to drug treatment resistant depressive symptoms in different conditions. The patients had previously undergone two psychopharmacological attempts with adequate dosage and time, who had been considered candidates for electroconvulsive therapy (ECT) if they did not respond to any conventional treatment. A total of 62.7% had mood disorder, 13.1% obsessive-compulsive disorders (OCT), 7.5% cognitive disorders, 4.7% personality disorders and 3.7% were psychiatric disorders. Mean age of the group was 49.98 years (SD = 17.09). The global results showed that the TMS provided some degree of improvement in 48.6%, although only half, that is 24.3%, maintained it beyond week 12. Efficacy by diagnoses showed a significant difference in favor of affective disorders. In the case of bipolar disorders in the depressive phase, there was improvement in 88.9%, which was maintained in 66.7% of the patients treated. No differences in efficacy were found within each one of the groups diagnosed based on gender, age or presence of personality disorders. The efficacy of the ECT was similar to the TMS in the group in which it had to be applied in comparison with the general group. New studies are proposed with the inclusion of the TMS for resistant-depression treatment protocols in a step prior to the ECT and even before all the drug treatments had been attempted, combining it with them for their potentiation. PMID:20976637

  16. [Effectiveness of transcranial magnetic therapy in the complex treatment of alcohol abstinent syndrome].

    PubMed

    Staroverov, A T; Zhukov, O B; Ra?gorodski?, Iu M

    2008-01-01

    Fifty-four abstinent alcohol-dependent patients have been studied. Twenty-nine patients (a main group) received, along with basic therapy, a physiotherapeutic treatment (transcranial dynamic magnetic therapy) and 25 patients (a control group) received only basic therapy. The comparison of the efficacy of treatment in patients of the main and control groups revealed the benefits of transcranial dynamic magnetic therapy in CNS function, performance on memory and attention tests, state of autonomic nervous system and psychoemotional state of patients (the reduction of anxiety and depression). PMID:18833174

  17. High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

    NASA Astrophysics Data System (ADS)

    Salvador, R.; Miranda, P. C.; Roth, Y.; Zangen, A.

    2009-05-01

    Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/\\sqrt 2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

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

    PubMed

    Nakamura, Motoaki

    2012-01-01

    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

  19. Effects of diazepam, baclofen and thiopental on the silent period evoked by transcranial magnetic stimulation in humans

    Microsoft Academic Search

    M. Inghilleri; A. Berardelli; P. Marchetti; M. Manfredi

    1996-01-01

    The cortical silent period evoked by magnetic transcranial stimulation and the peripheral silent period were studied in healthy subjects after intravenous injection of diazepam, baclofen or thiopental. None of the drugs tested changed the peripheral silent period. But, unexpectedly, diazepam significantly shortened the cortical silent period, the inhibitory effect lasting about 30 min. In experiments using paired transcranial stimuli, the

  20. MRI-free neuronavigation for transcranial magnetic stimulation in severe depression

    E-print Network

    Paris-Sud XI, Université de

    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

  1. Neuronavigated repetitive transcranial magnetic stimulation in patients with tinnitus: a short case series

    Microsoft Academic Search

    Peter Eichhammer; Berthold Langguth; Jörg Marienhagen; Tobias Kleinjung; Göran Hajak

    2003-01-01

    BackgroundClinical as well as neurophysiological and neuroimaging data suggest that chronic tinnitus resembles neuropsychiatric syndromes characterized by focal brain activation. Low-frequency repetitive transcranial magnetic stimulation (rTMS) has been proposed as an efficient method in treating brain hyperexcitability disorders by reducing cortical excitability.

  2. Transcranial Magnetic Stimulation Reveals Attentional Feedback to Area V1 during Serial Visual Search

    E-print Network

    Paris-Sud XI, Université de

    during Serial Visual Search. PLoS ONE 6(5): e19712. doi:10.1371/journal.pone.0019712 Editor: Michael H (1980) [1], visual search experiments have been used to study attention [1­4]. Visual search tasksTranscranial Magnetic Stimulation Reveals Attentional Feedback to Area V1 during Serial Visual

  3. Transcranial magnetic stimulation and the motor learning-associated cortical plasticity

    Microsoft Academic Search

    Milos Ljubisavljevic

    2006-01-01

    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

  4. Transcranial magnetic stimulation: a historical evaluation and future prognosis of therapeutically relevant ethical concerns

    Microsoft Academic Search

    Jared C Horvath; Jennifer M Perez; Lachlan Forrow; Felipe Fregni; Alvaro Pascual-Leone

    2010-01-01

    Transcranial Magnetic Stimulation (TMS) is a non-invasive neurostimulatory and neuromodulatory technique increasingly used in clinical and research practices around the world. Historically, the ethical considerations guiding the therapeutic practice of TMS were largely concerned with aspects of subject safety in clinical trials. While safety remains of paramount importance, the recent US Food and Drug Administration approval of the Neuronetics NeuroStar

  5. Goal: Investigation of the underlying biophysical effects of transcranial magnetic stimulation (TMS).

    E-print Network

    Ø Ø Ø Ø Goal: Investigation of the underlying biophysical effects of transcranial magnetic, J., Reichenbach, J.R. (2010), Influence of anisotropic electrical conductivity in white matter/m) 3. Direct mapping with adjusted scale factor (Tuch 2001; Wolters, 2009) For each anisotropic model

  6. Middle Cerebral Artery Stenoses: Assessment by Magnetic Resonance Angiography and Transcranial Doppler Ultrasound

    Microsoft Academic Search

    J. Röther; A. Schwartz; K. U. Wentz; W. Rautenberg; M. Hennerici

    1994-01-01

    Magnetic resonance angiography (MRA) findings of uni- or bilateral middle cerebral artery (MCA) stenosis were compared with results of transcranial Doppler ultrasound (TCD) and digital subtraction angiography (DSA). Eighteen patients with 22 MCA stenoses were selected by TCD criteria. To evaluate the diagnostic accuracy of MRA, TCD and DSA, criteria for classification of stenoses were established. MRA confirmed 21 MCA

  7. All Talk and No Action: A Transcranial Magnetic Stimulation Study of Motor Cortex Activation during

    E-print Network

    Caramazza, Alfonso

    All Talk and No Action: A Transcranial Magnetic Stimulation Study of Motor Cortex Activation during proposed that the premotor and motor areas are critical for the representation of words that refer, it may still be the case that other anterior motor regions are engaged in processing a word

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

    ERIC Educational Resources Information Center

    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

    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…

  9. Transcranial magnetic stimulation of posterior parietal cortex affects decisions of hand choice

    E-print Network

    Ivry, Rich

    for an action is one of the most frequent decisions people make in everyday behavior. Using a speeded reachingTranscranial magnetic stimulation of posterior parietal cortex affects decisions of hand choice, Pasadena, CA, and approved August 26, 2010 (received for review May 10, 2010) Deciding which hand to use

  10. 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

    Mark S George; Gary Aston-Jones

    2010-01-01

    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

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

    PubMed Central

    Moloney, Tonya M.; Witney, Alice G.

    2014-01-01

    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

  12. Motor cortex-induced plasticity by noninvasive brain stimulation: a comparison between transcranial direct current stimulation and transcranial magnetic stimulation.

    PubMed

    Simis, Marcel; Adeyemo, Bamidele O; Medeiros, Liciane F; Miraval, Forella; Gagliardi, Rubens J; Fregni, Felipe

    2013-12-01

    The aim of this study was to test and compare the effects of a within-subject design of repetitive transcranial magnetic stimulation (rTMS) [coupled with sham transcranial direct current stimulation (tDCS)] and tDCS (coupled with sham rTMS) on the motor cortex excitability and also compare the results against sham tDCS/sham rTMS. We conducted a double-blinded, randomized, sham-controlled, cross-over trial. Eleven right-handed, healthy individuals (five women, mean age: 39.8 years, SD 13.4) received the three interventions (cross-over design) in a randomized order: (a) high-frequency (HF) rTMS (+sham tDCS), (b) anodal tDCS (+sham rTMS), and (c) sham stimulation (sham rTMS+sham tDCS). Cortical excitability measurements [motor threshold, motor evoked potential (MEP), intracortical facilitation and inhibition, and transcallosal inhibition] and motor behavioral assessments were used as outcome measures. Between-group analysis of variance showed that MEP amplitude after HF rTMS was significantly higher than MEP amplitude after anodal tDCS (P=0.001). Post-hoc analysis showed a significant increase in MEP amplitude after HF rTMS (25.3%, P=0.036) and a significant decrease in MEP amplitude after anodal tDCS (-32.7%, P=0.001). There was a similar increase in motor function as indexed by Jebsen-Taylor Hand Function Test in the two active groups compared with sham stimulation. In conclusion, here, we showed that although both techniques induced similar motor gains, they induce opposing results in cortical excitability. HF rTMS is associated with an increase in corticospinal excitability, whereas 20 min of tDCS induces the opposite effect. We discuss potential implications of these results to future clinical experiments using rTMS or tDCS for motor function enhancement. PMID:24100412

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

    Microsoft Academic Search

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

    1992-01-01

    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

  14. Activation and suppression of the sternocleidomastoid muscle induced by transcranial magnetic stimulation

    Microsoft Academic Search

    T. Odergren; I. Rimpiläinen

    1996-01-01

    Responses in the sternocleidomastoid muscle (SCM) induced by transcranial magnetic stimulation (TMS) were investigated in 10 healthy subjects. Stimuli were given with the Dantec MagLite™ magnetic stimulator using a 12.5 cm circular coil with counter-clockwise current direction. Monopolar needle electrodes with isolated shafts were used for simultaneous bilateral electromyographic (EMG) recordings of the SCM. TMS given on either side invariably

  15. Introducing navigated transcranial magnetic stimulation as a refined brain mapping methodology

    Microsoft Academic Search

    Timo Krings; Keith H. Chiappa; Henrik Foltys; Marcus H. T. Reinges; Rees G. Cosgrove; Armin Thron

    2001-01-01

    .   A major intrinsic limitation of transcranial magnetic stimulation (TMS) to map the human brain lies in the unclear relationship\\u000a between the position of the stimulating coil on the scalp and the underlying stimulated cortex. The relationship between structure\\u000a and function as the major feature constituting a brain mapping modality can therefore not be established. Recent advances\\u000a in image processing

  16. Reduction of human visual cortex excitability using 1-Hz transcranial magnetic stimulation.

    PubMed

    Boroojerdi, B; Prager, A; Muellbacher, W; Cohen, L G

    2000-04-11

    The effects of low-frequency (1-Hz) repetitive transcranial magnetic stimulation on visual cortex excitability were investigated by measuring phosphene thresholds (PTs) and stimulus-response curves. Stimulation over the visual cortex led to significantly decreased visual cortex excitability, expressed as an increase in PT. The motor threshold of the hand muscles did not change, indicating the topographic specificity of this effect. This intervention may be useful in situations associated with a hyperexcitable visual cortex. PMID:10751273

  17. Variability of motor potentials evoked by transcranial magnetic stimulation depends on muscle activation

    Microsoft Academic Search

    Warren G. Darling; Steven L. Wolf; Andrew J. Butler

    2006-01-01

    The purpose of this research was to determine whether motor cortex excitability assessed using transcranial magnetic stimulation (TMS) is less variable when subjects maintain a visually controlled low-level contraction of the muscle of interest. We also examined the dependence of single motor evoked potential (MEP) amplitude on stimulation intensity and pre-stimulus muscle activation level using linear and non-linear multiple regression

  18. Inter and intra-individual variability of paired-pulse curves with transcranial magnetic stimulation (TMS)

    Microsoft Academic Search

    Fumiko Maeda; Massimo Gangitano; Mark Thall; Alvaro Pascual-Leone

    2002-01-01

    Objectives: Previous studies have evaluated the variability of motor thresholds (MTs) and amplitude of motor-evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) within and across individuals. Here we evaluate the reproducibility and inter-hemispheric variability of measures of cortical excitability using the ‘conventional’ paired-pulse (PP) TMS technique.Methods: We studied PP curves of the left and right hemisphere in 10 healthy subjects

  19. Priming Stimulation Enhances the Depressant Effect of Low Frequency Repetitive Transcranial Magnetic Stimulation

    Microsoft Academic Search

    Meenakshi B. Iyer; Nicole Schleper; Eric M. Wassermann

    Low-frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) can depress the excitability of the cortex locally and has been proposed for the treatment of disorders such as schizophrenia and epilepsy. Some have speculated that the depressant effect is related to long-term depression (LTD) of cortical synapses. Because in vitro LTD can be enhanced by pretreatment of synapses with higher- frequency

  20. A Transcranial Magnetic Stimulator Inducing Near-Rectangular Pulses With Controllable Pulse Width (cTMS)

    Microsoft Academic Search

    Angel V. Peterchev; Reza Jalinous; Sarah H. Lisanby

    2008-01-01

    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 6 kA, enabling PW control from 5 mus to over 100 mus. The near-rectangular induced electric field pulses use 2%-34% less energy

  1. Repetitive paired-pulse transcranial magnetic stimulation affects corticospinal excitability and finger tapping in Parkinson's disease

    Microsoft Academic Search

    Martin Sommer; Torsten Kamm; Frithjof Tergau; Gudrun Ulm; Walter Paulus

    2002-01-01

    Objectives: To study the effect of long trains of a recently established conditioning-test paired-pulse repetitive transcranial magnetic stimulation (rTMS) paradigm on corticospinal excitability and finger tapping speed.Methods: We applied 900 inhibiting or facilitating paired-pulses or 900 real or sham single stimuli at 1Hz over the motor cortex contralateral to the dominant hand of 9 healthy subjects and contralateral to the

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

    Microsoft Academic Search

    L. S. Boylan; S. L. Pullman; S. H. Lisanby; K. E. Spicknall; H. A. Sackeim

    2001-01-01

    Objectives: To evaluate the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS) for Parkinson's disease (PD) by delivering stimulation at higher intensity and frequency over longer time than in previous research. Promising beneficial effects on movement during or after rTMS have been reported.Methods: Ten patients with idiopathic PD were enrolled in a randomized crossover study comparing active versus sham rTMS

  3. Fundamentals of Transcranial Electric and Magnetic Stimulation Dose: Definition, Selection, and Reporting Practices

    PubMed Central

    Peterchev, Angel V.; Wagner, Timothy A.; Miranda, Pedro C.; Nitsche, Michael A.; Paulus, Walter; Lisanby, Sarah H.; Pascual-Leone, Alvaro; Bikson, Marom

    2011-01-01

    The growing use of transcranial electric and magnetic (EM) brain stimulation in basic research and in clinical applications necessitates a clear understanding of what constitutes the dose of EM stimulation and how it should be reported. The biological effects of EM stimulation are mediated through an electromagnetic field injected (via electric stimulation) or induced (via magnetic stimulation) in the body. Therefore, transcranial EM stimulation dose ought to be defined by all parameters of the stimulation device that affect the electromagnetic field generated in the body, including the stimulation electrode or coil configuration parameters: shape, size, position, and electrical properties, as well as the electrode or coil current (or voltage) waveform parameters: pulse shape, amplitude, width, polarity, and repetition frequency; duration of and interval between bursts or trains of pulses; total number of pulses; and interval between stimulation sessions and total number of sessions. Knowledge of the electromagnetic field generated in the body may not be sufficient but is necessary to understand the biological effects of EM stimulation. We believe that reporting of EM stimulation dose should be guided by the principle of reproducibility: sufficient information about the stimulation parameters should be provided so that the dose can be replicated. This paper provides fundamental definition and principles for reporting of dose that encompass any transcranial EM brain stimulation protocol. PMID:22305345

  4. Combined use of transcranial magnetic stimulation and metal electrode implants: a theoretical assessment of safety considerations

    NASA Astrophysics Data System (ADS)

    Golestanirad, Laleh; Rouhani, Hossein; Elahi, Behzad; Shahim, Kamal; Chen, Robert; Mosig, Juan R.; Pollo, Claudio; Graham, Simon J.

    2012-12-01

    This paper provides a theoretical assessment of the safety considerations encountered in the simultaneous use of transcranial magnetic stimulation (TMS) and neurological interventions involving implanted metallic electrodes, such as electrocorticography. Metal implants are subject to magnetic forces due to fast alternating magnetic fields produced by the TMS coil. The question of whether the mechanical movement of the implants leads to irreversible damage of brain tissue is addressed by an electromagnetic simulation which quantifies the magnitude of imposed magnetic forces. The assessment is followed by a careful mechanical analysis determining the maximum tolerable force which does not cause irreversible tissue damage. Results of this investigation provide useful information on the range of TMS stimulator output powers which can be safely used in patients having metallic implants. It is shown that conventional TMS applications can be considered safe when applied on patients with typical electrode implants as the induced stress in the brain tissue remains well below the limit of tissue damage.

  5. Priming Frequencies of Transcranial Magnetic Stimulation over Wernicke's

    E-print Network

    Pallier, Christophe

    of TMS is electromagnetic induction, in which a time-varying magnetic field generated by a conductive on motor cortex, the impact of TMS frequency on other brain regions, particularly on those involved

  6. Sex differences in antidepressant-like effect of chronic repetitive transcranial magnetic stimulation in rats

    Microsoft Academic Search

    Yuye Yang; Wei Li; Bin Zhu; Yanyou Liu; Bo Yang; Hongxing Wang; Zhengrong Wang

    2007-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neurophysiological technique. Pre-clinical and clinical studies supported that rTMS might have antidepressant effects. However, whether antidepressant effect of chronic rTMS is gender-dependent is still unknown. In this study, male and female Wistar rats received 10-day rTMS (4 trains of 15 Hz; 200 stimuli\\/day; 1.0 T) or control condition, and then were subjected to the forced-swim test

  7. Corticomotor control of the genioglossus in awake OSAS patients: a transcranial magnetic stimulation study

    PubMed Central

    Sériès, Frédéric; Wang, Wei; Similowski, Thomas

    2009-01-01

    Background Upper airway collapse does not occur during wake in obstructive sleep apnea patients. This points to wake-related compensatory mechanisms, and possibly to a modified corticomotor control of upper airway dilator muscles. The objectives of the study were to characterize the responsiveness of the genioglossus to transcranial magnetic stimulation during respiratory and non-respiratory facilitatory maneuvers in obstructive sleep apnea patients, and to compare it to the responsiveness of the diaphragm, with reference to normal controls. Methods Motor evoked potentials of the genioglossus and of the diaphragm, with the corresponding motor thresholds, were recorded in response to transcranial magnetic stimulation applied during expiration, inspiration and during maximal tongue protraction in 13 sleep apnea patients and 8 normal controls. Main Results In the sleep apnea patients: 1) combined genioglossus and diaphragm responses occurred more frequently than in controls (P < 0.0001); 2) the amplitude of the genioglossus response increased during inspiratory maneuvers (not observed in controls); 3) the latency of the genioglossus response decreased during tongue protraction (not observed in controls). A significant negative correlation was found between the latency of the genioglossus response and the apnea-hypopnea index; 4) the difference in diaphragm and genioglossus cortico-motor responses during tongue protraction and inspiratory loading differed between sleep apnea and controls. Conclusion Sleep apnea patients and control subjects differ in the response pattern of the genioglossus and of the diaphragm to facilitatory maneuvers, some of the differences being related to the frequency of sleep-related events. PMID:19678922

  8. 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

    Roland Sparing; Felix M. Mottaghy

    2008-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

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

    Microsoft Academic Search

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

    1996-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  12. Spinal Cord-Evoked Potentials and Muscle Responses Evoked by Transcranial Magnetic Stimulation in 10 Awake Human Subjects

    Microsoft Academic Search

    David A. Houlden; Michael L. Schwartz; Charles H. Tator; Peter Ashby; William A. MacKay

    1999-01-01

    Transcranial magnetic stimulation (TCMS) causes leg muscle contractions, but the neural structures in the brain that are activated by TCMS and their relationship to these leg muscle responses are not clearly understood. To elucidate this, we concomitantly recorded leg muscle responses and thoracic spinal cord-evoked potentials (SCEPs) after TCMS for the first time in 10 awake, neurologically intact human subjects.

  13. Short-Term Effects of Repetitive Transcranial Magnetic Stimulation on Speech and Voice in Individuals with Parkinson’s Disease

    Microsoft Academic Search

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

    2010-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  15. Abnormal conditioning effect of transcranial magnetic stimulation on soleus H-reflex during voluntary movement in Parkinson's disease

    Microsoft Academic Search

    H Morita; M Shindo; S Morita; T Hashimoto; T Tada; S Ikeda

    2002-01-01

    Objectives: The objective of this study is to clarify the participation of cortical motor control abnormality in the motor dysfunction of Parkinson's disease (PD), especially at the onset of movement.Methods: Conditioning effects of transcranial magnetic simulation (TMS) on the soleus (SOL) H-reflex evoked with tibial nerve stimulation were examined in 19 patients with PD and 10 normal volunteers. Experiments were

  16. Sensed presence and mystical experiences are predicted by suggestibility, not by the application of transcranial weak complex magnetic fields

    Microsoft Academic Search

    Pehr Granqvist; Mats Fredrikson; Patrik Unge; Andrea Hagenfeldt; Sven Valind; Dan Larhammar; Marcus Larsson

    2005-01-01

    Transcranial magnetic stimulation (TMS) with weak (micro Tesla) complex waveform fields have been claimed to evoke the sensed presence of a sentient being in up to 80% in the general population. These findings have had a questionable neurophysiological foundation as the fields are approximately six orders of magnitude weaker than ordinary TMS fields. Also, no independent replication has been reported.

  17. [Transcranial magnetic therapy in the treatment of psychoautonomous disturbances in children with diabetes mellitus type 1].

    PubMed

    Filina, N Iu; Bolotova, N V; Manukian, V Iu; Nikolaeva, N V; Kompaniets, O V

    2009-01-01

    Results of a clinical-physiological study of 80 children with diabetes mellitus type 1 with psychoautonomous disturbances are presented. Forty patients of the main group received transcranial magnetic therapy (TcMT), 40 patients of the control group had placebo sessions of TcMT with magnetic power supply switched off. TcMT was applied using bitemporal method, running regime with modulation frequency 1-10 Hz. Patients received 10 sessions. Positive changes were found in the main group compared to the controls. In the main group, TcMT sessions allowed to normalize the autonomous status in 75% of children and to improve psychoemotional state in 55%. The correction of psychoemotional status of children changed their behavior towards diabetes, improved control and compensation of the disease. PMID:19738565

  18. New perspectives in transcranial magnetic stimulation: epilepsy, consciousness and the perturbational approach.

    PubMed

    Manganotti, Paolo; Del Felice, Alessandra

    2013-01-01

    Transcranial magnetic stimulation (TMS) evolved from a simple method to stimulate the motor cortex to an invaluable tool for multiple diagnostic, research, and therapeutic applications. A further development of this noninvasive brain stimulation technique is concomitant electroencephalographic (EEG) recording during TMS. The theoretical underpinnings and the technological innovation of TMS-EEG co-registration have opened new ways to study brain excitability in neurological conditions previously investigated with conventional EEG alone. A further advance in TMS research applications is the perturbational approach: magnetic pulses can interfere not only with dynamic, often pathological rhythms in epilepsy or altered consciousness states, but also modulate physiological states such as sleep and sleep deprivation. So applied, TMS-EEG co-registration can reveal different neurophysiological and behavioral patterns in the awake state, sleep or sleep deprivation. In this review, we discuss the use of TMS and TMS-EEG co-registration in epilepsy, a still rather limited although promising area of study. PMID:23001632

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

    PubMed

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

    2015-01-01

    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

  20. Phantom Limb Pain: Low Frequency Repetitive Transcranial Magnetic Stimulation in Unaffected Hemisphere

    PubMed Central

    Di Rollo, Andrea; Pallanti, Stefano

    2011-01-01

    Phantom limb pain is very common after limb amputation and is often difficult to treat. The motor cortex stimulation is a valid treatment for deafferentation pain that does not respond to conventional pain treatment, with relief for 50% to 70% of patients. This treatment is invasive as it uses implanted epidural electrodes. Cortical stimulation can be performed noninvasively by repetitive transcranial magnetic stimulation (rTMS). The stimulation of the hemisphere that isn't involved in phantom limb (unaffected hemisphere), remains unexplored. We report a case of phantom limb pain treated with 1 Hz rTMS stimulation over motor cortex in unaffected hemisphere. This stimulation produces a relevant clinical improvement of phantom limb pain; however, further studies are necessary to determine the efficacy of the method and the stimulation parameters. PMID:21629848

  1. Daily left prefrontal repetitive transcranial magnetic stimulation for medication-resistant burning mouth syndrome.

    PubMed

    Umezaki, Y; Badran, B W; Gonzales, T S; George, M S

    2015-08-01

    Burning mouth syndrome (BMS) is a persistent and chronic burning sensation in the mouth in the absence of any abnormal organic findings. The pathophysiology of BMS is unclear and its treatment is not fully established. Although antidepressant medication is commonly used for treatment, there are some medication-resistant patients, and a new treatment for medication-resistant BMS is needed. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technology approved by the US Food and Drug Administration (FDA) for the treatment of depression. Recent studies have found beneficial effects of TMS for the treatment of pain. A case of BMS treated successfully with daily left prefrontal rTMS over a 2-week period is reported here. Based on this patient's clinical course and a recent pain study, the mechanism by which TMS may act to decrease the burning pain is discussed. PMID:25979192

  2. Corticospinal excitability during painful self-stimulation in humans: a transcranial magnetic stimulation study.

    PubMed

    Fadiga, Luciano; Craighero, Laila; Dri, Guanita; Facchin, Patrizia; Destro, Maddalena Fabbri; Porro, Carlo A

    2004-05-01

    We investigated changes in the corticospinal pattern of activity in healthy volunteers during sustained noxious and non-noxious mechanical stimulation of the first hand digit, resulting from active (self-stimulation) or passive (externally-induced) pressing against a sharp or blunted tip. The results indicate that, in order to press a finger onto a noxious stimulus with the same force generated to press onto a non-noxious one, the motor cortex adopts a peculiar strategy in terms of recruitment of motor units. This is reflected by an increase of corticospinal excitability (as revealed by motor potentials evoked by transcranial magnetic stimulation of the contralateral primary motor cortex) and EMG activity of agonist muscles, possibly related to an increase of motor unit synchronization. PMID:15135940

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

    PubMed Central

    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

    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

  4. Transcranial magnetic stimulation reveals complex cognitive control representations in the rostral frontal cortex.

    PubMed

    Bahlmann, J; Beckmann, I; Kuhlemann, I; Schweikard, A; Münte, T F

    2015-08-01

    Convergent evidence suggests that the lateral frontal cortex is at the heart of a brain network subserving cognitive control. Recent theories assume a functional segregation along the rostro-caudal axis of the lateral frontal cortex based on differences in the degree of complexity of cognitive control. However, the functional contribution of specific rostral and caudal sub-regions remains elusive. Here we investigate the impact of disrupting rostral and caudal target regions on cognitive control processes, using Transcranial Magnetic Stimulation (TMS). Participants performed three different task-switching conditions that assessed differences in the degree of complexity of cognitive control processes, after temporally disrupting rostral, or caudal target regions, or a control region. Disrupting the rostral lateral frontal region specifically impaired behavioral performance of the most complex task-switching condition, in comparison to the caudal target region and the control region. These novel findings shed light on the neuroanatomical architecture supporting control over goal-directed behavior. PMID:26037799

  5. Unconscious modulation of motor cortex excitability revealed with transcranial magnetic stimulation.

    PubMed

    Théoret, Hugo; Halligan, Erin; Kobayashi, Masahito; Merabet, Lotfi; Pascual-Leone, Alvaro

    2004-03-01

    The neuronal effects of sensory events that do not enter conscious awareness have been reported in numerous pathological conditions and in normal subjects. In the present study, unconscious modulation of corticospinal excitability was probed in healthy volunteers with transcranial magnetic stimulation (TMS). TMS-induced motor evoked potentials (MEPs) were collected from the first dorsal interosseus muscle while subjects performed a masked semantic priming task that has been shown to elicit covert motor cortex activations. Our data show that the amplitude of the MEPs is modulated by an unseen prime, in line with temporal patterns revealed with event related potentials. These data confirm previous reports showing specific motor neural responses associated with an unseen visual stimulus and establish TMS as a valuable tool in the study of the neural correlates of consciousness. PMID:14745468

  6. The numeric calculation of eddy current distributions in transcranial magnetic stimulation.

    PubMed

    Tsuyama, Seichi; Hyodo, Akira; Sekino, Masaki; Hayami, Takehito; Ueno, Shoogo; Iramina, Keiji

    2008-01-01

    Transcranial magnetic stimulation (TMS) is a method to stimulate neurons in the brain. It is necessary to obtain eddy current distributions and determine parameters such as position, radius and bend-angle of the coil to stimulate target area exactly. In this study, we performed FEM-based numerical simulations of eddy current induced by TMS using three-dimentional human head model with inhomogeneous conductivity. We used double-cone coil and changed the coil radius and bend-angle of coil. The result of computer simulation showed that as coil radius increases, the eddy current became stronger everywhere. And coil with bend-angle of 22.5 degrees induced stronger eddy current than the coil with bendangle of 0 degrees. Meanwhile, when the bend-angle was 45 degrees, eddy current became weaker than these two cases. This simulation allowed us to determine appropriate parameter easier. PMID:19163660

  7. Prefrontal repetitive transcranial magnetic stimulation as add on treatment in depression

    PubMed Central

    Garcia-Toro, M; Pascual-Leone, A; Romera, M; Gonzalez, A; Mico, J; Ibarra, O; Arnillas, H; Capllonch, I; Mayol, A; Tormos, J

    2001-01-01

    A growing number of studies report antidepressant effects of repetitive transcranial magnetic stimulation (rTMS) in patients with major depression. The hypothesis that high frequency (20Hz) rTMS (HF-rTMS) may speed up and strengthen the therapeutic response to sertraline in MD was tested. Twenty eight patients who had not yet received medication for the present depressive episode (n=12) or had failed a single trial of an antidepressant medication (n=16) were started on sertraline and randomised to receive either real of sham HF-rTMS. HF-rTMS was applied to the left dorsolateral prefrontal area in daily sessions (30 trains of 2 s, 20-40 s intertrain interval, at 90% motor threshold) on 10 consecutive working days. The results suggest that in this patient population, HF-rTMS does not add efficacy over the use of standard antidepressant medication.?? PMID:11561046

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

    PubMed

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

    2014-01-01

    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

  9. Assessment and modulation of neuroplasticity in rehabilitation with transcranial magnetic stimulation

    PubMed Central

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

    2013-01-01

    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

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

    PubMed Central

    Jalinous, Reza; Lisanby, Sarah H.

    2013-01-01

    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

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

    PubMed Central

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

    2014-01-01

    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

  12. Deep brain stimulation of both subthalamic nucleus and internal globus pallidus restores intracortical inhibition in Parkinson's disease paralleling apomorphine effects: a paired magnetic stimulation study

    Microsoft Academic Search

    M Pierantozzi; M. G Palmieri; P Mazzone; M. G Marciani; P. M Rossini; A Stefani; P Giacomini; A Peppe; P Stanzione

    2002-01-01

    Objective: We investigated the effect of bilateral subthalamic nucleus (STN) and internal globus pallidus (GPi) deep brain stimulation (DBS) on intracortical inhibition (ICI) in patients with advanced Parkinson's disease (PD).Methods: The activity of intracortical inhibitory circuits was studied in 4 PD patients implanted with stimulating electrodes both in STN and GPi by means of paired-pulse transcranial magnetic stimulation, delivered in

  13. 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

    Eric M. Wassermann

    1998-01-01

    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

  14. flexTMS--a novel repetitive transcranial magnetic stimulation device with freely programmable stimulus currents.

    PubMed

    Gattinger, Norbert; Moessnang, Georg; Gleich, Bernhard

    2012-07-01

    Transcranial magnetic stimulation (TMS) is able to noninvasively excite neuronal populations due to brief magnetic field pulses. The efficiency and the characteristics of stimulation pulse shapes influence the physiological effect of TMS. However, commercial devices allow only a minimum of control of different pulse shapes. Basically, just sinusoidal and monophasic pulse shapes with fixed pulse widths are available. Only few research groups work on TMS devices with controllable pulse parameters such as pulse shape or pulse width. We describe a novel TMS device with a full-bridge circuit topology incorporating four insulated-gate bipolar transistor (IGBT) modules and one energy storage capacitor to generate arbitrary waveforms. This flexible TMS (flexTMS ) device can generate magnetic pulses which can be adjusted with respect to pulse width, polarity, and intensity. Furthermore, the equipment allows us to set paired pulses with a variable interstimulus interval (ISI) from 0 to 20 ms with a step size of 10  ?s. All user-defined pulses can be applied continually with repetition rates up to 30 pulses per second (pps) or, respectively, up to 100 pps in theta burst mode. Offering this variety of flexibility, flexTMS will allow the enhancement of existing TMS paradigms and novel research applications. PMID:22531742

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

    PubMed Central

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

    2014-01-01

    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

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

    Microsoft Academic Search

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

    2007-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is a novel, non-invasive neurological and psychiatric tool. The low-frequency (1Hz or less) rTMS is likely to play a particular role in its mechanism of action with different effects in comparison with high-frequency (>1Hz) rTMS. There is limited information regarding the effect of low-frequency rTMS on spatial memory. In our study, each male Wistar rat

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

    Microsoft Academic Search

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

    2000-01-01

    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

  18. Electromagnetic characteristics of eccentric figure-eight coils for transcranial magnetic stimulation: A numerical study

    NASA Astrophysics Data System (ADS)

    Kato, Takuya; Sekino, Masaki; Matsuzaki, Taiga; Nishikawa, Atsushi; Saitoh, Youichi; Ohsaki, Hiroyuki

    2012-04-01

    Repetitive transcranial magnetic stimulation (rTMS) is effective for treatment of several neurological and psychiatric diseases. We proposed an eccentric figure-eight coil, which induces strong eddy currents in the target brain tissue. In this study, numerical analyses were carried out to obtain magnetic field distribution of the eccentric figure-eight coil and eddy current in the brain. The analyses were performed with various coil design parameters, such as the outer and inner diameters and number of turns, to investigate the influence of these parameters on the coil characteristics. Increases in the inner diameter, outer diameter, and number of turns caused increases in the maximum eddy current densities. Coil inductance, working voltage, and heat generation also became higher with the increases in these design parameters. In order to develop a compact stimulator system for use at home, we need to obtain strong eddy current density, keeping the working voltage as low as possible. Our results show that it is effective to enlarge the outer diameter.

  19. Disorders of consciousness: further pathophysiological insights using motor cortex transcranial magnetic stimulation.

    PubMed

    Lapitskaya, Natallia; Coleman, Martin R; Nielsen, Joergen Feldbaek; Gosseries, Olivia; de Noordhout, Alain Maertens

    2009-01-01

    Transcranial magnetic stimulation (TMS) is a noninvasive means of investigating the function, plasticity, and excitability of the human brain. TMS induces a brief intracranial electrical current, which produces action potentials in excitable cells. Stimulation applied over the motor cortex can be used to measure overall excitability of the corticospinal system, somatotopic representation of muscles, and subsequent plastic changes following injury. The facilitation and inhibition characteristics of the cerebral cortex can also be compared using the modulatory effect of a conditioning stimulus preceding a test stimulus. So called paired-pulse protocols have been used in humans and animals to assess GABA (gamma-amino-butyric acid)-ergic function and may have a future role directing therapeutic interventions. Indeed, repetitive magnetic stimulation, where intracranial currents are induced by repetitive stimulation higher than 1 Hz, has been shown to modulate brain responses to sensory and cognitive stimulation. Here, we summarize information gathered using TMS with patients in coma, vegetative state, and minimally conscious state. Although in the early stages of investigation, there is preliminary evidence that TMS represents a promising tool by which to elucidate the pathophysiological sequelae of impaired consciousness and potentially direct future therapeutic interventions. We will discuss the methodology of work conducted to date, as well as debate the general limitations and pitfalls of TMS studies in patients with altered states of consciousness. PMID:19818902

  20. Relieving pain in rheumatology patients: repetitive transcranial magnetic stimulation (rTMS), a developing approach.

    PubMed

    Pérocheau, Dominique; Laroche, Françoise; Perrot, Serge

    2014-01-01

    Transcranial magnetic stimulation (TMS) is a non-invasive method for activating specific areas of the brain. There are two variants, repetitive TMS (rTMS) and direct TMS. Rapid changes in an electrical current induce a magnetic field, which in turn induces an electrical current in a nearby conductor. When a coil is positioned over the brain, rTMS delivers very brief and painless magnetic pulses to the brain. Initially, rTMS was developed as a treatment for depression. Since then, potential indications have been extended to the treatment of chronic pain, most notably in patients with rheumatic diseases. Thus, active research is being conducted into rTMS effects in fibromyalgia, chronic low back pain, and type I complex regional pain syndrome. Studies have established that rTMS is safe; provides pain relief, at least in the short-term; and improves the psychological correlates of chronic pain. These data support further development efforts with the goal of using rTMS in patients with chronic pain, including those with rheumatic diseases. French physicians have shown a high level of interest in rTMS, and the first French recommendations for using this method were issued in 2011. Further research is needed to determine the optimal stimulation parameters, session frequency, and session duration, as well as the best indications. Physicians who see many patients with chronic pain, such as rheumatologists, should be aware of this developing non-pharmacological and safe treatment modality, which can be of considerable help to their patients. PMID:23787057

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

    PubMed Central

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

    2014-01-01

    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

  2. Motor cortex excitability correlates with novelty seeking in social anxiety: a transcranial magnetic stimulation investigation.

    PubMed

    Pallanti, Stefano; Borgheresi, Alessandra; Pampaloni, Ilenia; Giovannelli, Fabio; Bernardi, Silvia; Cantisani, Andrea; Zaccara, Gaetano; Cincotta, Massimo

    2010-08-01

    Social anxiety disorder (SAD) is characterised by fear of scrutiny by other people, avoidance of social situations and vegetative/motor symptomatology. The correlation between reduced striatal dopaminergic (DA) function, SAD motor symptoms and the high occurrence of SAD in patients with Parkinson's disease (PD), suggests a link between SAD and movement diseases caused by dopamine dysfunction. However, little is known about the electrophysiological aspects of SAD. We applied single- and paired-pulse transcranial magnetic stimulation (TMS) to investigate excitatory and inhibitory mechanisms of the primary motor cortex (M1) in 15 SAD patients and the relationship between these neurophysiological measures and clinical symptoms or temperamental traits. Data were compared with those obtained in 15 age- and sex-matched healthy volunteers. SAD patients showed significantly higher harm avoidance scores and lower novelty seeking scores when compared to controls. TMS measures did not significantly differ between groups. However, in SAD patients the cortical silent period (CSP) duration and the amount of long-interstimulus interval intracortical inhibition were significantly correlated with the NS score. Accordingly with NS reduction and CSP shortening reported in PD, the relationship between NS levels and the excitability of inhibitory circuits of the M1 may support the hypothesis that DA dysfunction could underlie NS deficits in SAD. Furthermore, these data suggest that "trait variables" (i.e., NS) are more closely related to neurophysiological measures than SAD symptoms, which represent "state variables" linked to social performance. PMID:20352252

  3. Opportunities for concurrent transcranial magnetic stimulation and electroencephalography to characterize cortical activity in stroke

    PubMed Central

    Sato, Sumire; Bergmann, Til Ole; Borich, Michael R.

    2015-01-01

    Stroke is the leading cause of disability in the United States. Despite the high incidence and mortality of stroke, sensitive and specific brain-based biomarkers predicting persisting disabilities are lacking. Both neuroimaging techniques like electroencephalography (EEG) and non-invasive brain stimulation (NIBS) techniques such as transcranial magnetic stimulation (TMS) have proven useful in predicting prognosis, recovery trajectories and response to rehabilitation in individuals with stroke. We propose, however, that additional synergetic effects can be achieved by simultaneously combining both approaches. Combined TMS-EEG is able to activate discrete cortical regions and directly assess local cortical reactivity and effective connectivity within the network independent of the integrity of descending fiber pathways and also outside the motor system. Studying cortical reactivity and connectivity in patients with stroke TMS-EEG may identify salient neural mechanisms underlying motor disabilities and lead to novel biomarkers of stroke pathophysiology which can then be used to assess, monitor, and refine rehabilitation approaches for individuals with significant disability to improve outcomes and quality of life after stroke. PMID:25999839

  4. Reduced postactivation depression of soleus H reflex and root evoked potential after transcranial magnetic stimulation.

    PubMed

    Andrews, Jennifer C; Stein, Richard B; Roy, François D

    2015-07-01

    Postactivation depression of the Hoffmann (H) reflex is associated with a transient period of suppression following activation of the reflex pathway. In soleus, the depression lasts for 100-200 ms during voluntary contraction and up to 10 s at rest. A reflex root evoked potential (REP), elicited after a single pulse of transcutaneous stimulation to the thoracolumbar spine, has been shown to exhibit similar suppression. The present study systematically characterized the effect of transcranial magnetic stimulation (TMS) on postactivation depression using double-pulse H reflexes and REPs. A TMS pulse reduced the period of depression to 10-15 ms for both reflexes. TMS could even produce postactivation facilitation of the H reflex, as the second reflex response was increased to 243 ± 51% of control values at the 75-ms interval. The time course was qualitatively similar for the REP, yet the overall increase was less. While recovery of the H reflex was slower in the relaxed muscle, the profile exhibited a distinct bimodal shape characterized by an early peak at the 25-ms interval, reaching 72 ± 23% of control values, followed by a trough at 50 ms, and then a gradual recovery at intervals > 50 ms. The rapid recovery of two successively depressed H reflexes, ?25 ms apart, was also possible with double-pulse TMS. The effect of the TMS-induced corticospinal excitation on postactivation depression may be explained by a combination of pre- and postsynaptic mechanisms, although further investigation is required to distinguish between them. PMID:25995355

  5. Induced Effects of Transcranial Magnetic Stimulation on the Autonomic Nervous System and the Cardiac Rhythm

    PubMed Central

    Cabrera, Anastasio; Perez, Juan O.; de la Rua, Jesus; Rojas, Niovi; Zhou, Qi; Pinzon-Ardila, Alberto; Gonzalez-Arias, Sergio M.

    2014-01-01

    Several standard protocols based on repetitive transcranial magnetic stimulation (rTMS) have been employed for treatment of a variety of neurological disorders. Despite their advantages in patients that are retractable to medication, there is a lack of knowledge about the effects of rTMS on the autonomic nervous system that controls the cardiovascular system. Current understanding suggests that the shape of the so-called QRS complex together with the size of the different segments and intervals between the PQRST deflections of the heart could predict the nature of the different arrhythmias and ailments affecting the heart. This preliminary study involving 10 normal subjects from 20 to 30 years of age demonstrated that rTMS can induce changes in the heart rhythm. The autonomic activity that controls the cardiac rhythm was indeed altered by an rTMS session targeting the motor cortex using intensity below the subject's motor threshold and lasting no more than 5 minutes. The rTMS activation resulted in a reduction of the RR intervals (cardioacceleration) in most cases. Most of these cases also showed significant changes in the Poincare plot descriptor SD2 (long-term variability), the area under the low frequency (LF) power spectrum density curve, and the low frequency to high frequency (LF/HF) ratio. The RR intervals changed significantly in specific instants of time during rTMS activation showing either heart rate acceleration or heart rate deceleration. PMID:25136660

  6. Comparison of spherical and realistically shaped boundary element head models for transcranial magnetic stimulation navigation

    PubMed Central

    Nummenmaa, Aapo; Stenroos, Matti; Ilmoniemi, Risto J.; Okada, Yoshio C.; Hämäläinen, Matti S.; Raij, Tommi

    2013-01-01

    Objective MRI-guided real-time transcranial magnetic stimulation (TMS) navigators that apply electromagnetic modeling have improved the utility of TMS. However, their accuracy and speed depends on the assumed volume conductor geometry. Spherical models found in present navigators are computationally fast but may be inaccurate in some areas. Realistically-shaped boundary-element models (BEMs) could increase accuracy at a moderate computational cost, but it is unknown which model features have the largest influence on accuracy. Thus, we compared different types of spherical models and BEMs. Methods Globally and locally fitted spherical models and different BEMs with either one or three compartments and with different skull-to-brain conductivity ratios (1/1 – 1/80) were compared against a reference BEM. Results The one-compartment BEM at inner skull surface was almost as accurate as the reference BEM. Skull/brain conductivity ratio in the range 1/10 – 1/80 had only a minor influence. BEMs were superior to spherical models especially in frontal and temporal areas (up to 20 mm localization and 40% intensity improvement); in motor cortex all models provided similar results. Conclusions One-compartment BEMs offer a good balance between accuracy and computational cost. Significance Realistically-shaped BEMs may increase TMS navigation accuracy in several brain areas, such as in prefrontal regions often targeted in clinical applications. PMID:23890512

  7. Disruption of Locomotor Adaptation with Repetitive Transcranial Magnetic Stimulation Over the Motor Cortex.

    PubMed

    Choi, Julia T; Bouyer, Laurent J; Nielsen, Jens Bo

    2015-07-01

    Locomotor patterns are adapted on a trial-and-error basis to account for predictable dynamics. Once a walking pattern is adapted, the new calibration is stored and must be actively de-adapted. Here, we tested the hypothesis that storage of newly acquired ankle adaptation in walking is dependent on corticospinal mechanisms. Subjects were exposed to an elastic force that resisted ankle dorsiflexion during treadmill walking. Ankle movement was adapted in <30 strides, leading to after-effects on removal of the force. We used a crossover design to study the effects of repetitive transcranial magnetic stimulation (TMS) over the primary motor cortex (M1), compared with normal adaptation without TMS. In addition, we tested the effects of TMS over the primary sensory cortex (S1) and premotor cortex (PMC) during adaptation. We found that M1 TMS, but not S1 TMS and PMC TMS, reduced the size of ankle dorsiflexion after-effects. The results suggest that suprathreshold M1 TMS disrupted the initial processes underlying locomotor adaptation. These results are consistent with the hypothesis that corticospinal mechanisms underlie storage of ankle adaptation in walking. PMID:24532321

  8. Factors Associated With Upper Extremity Motor Recovery After Repetitive Transcranial Magnetic Stimulation in Stroke Patients

    PubMed Central

    Lee, Jong Hwa; Kim, Sang Beom; Lee, Kyeong Woo; Kim, Min Ah; Lee, Sook Joung

    2015-01-01

    Objective To determine factors associated with motor recovery of the upper extremity after repetitive transcranial magnetic stimulation (rTMS) treatment in stroke patients. Methods Twenty-nine patients with subacute stroke participated in this study. rTMS was applied to the hand motor cortex for 10 minutes at a 110% resting motor threshold and 10 Hz frequency for two weeks. We evaluated the biographical, neurological, clinical, and functional variables, in addition to the motor-evoked potential (MEP) response. The Manual Function Test (MFT) was performed before, immediately after, and two weeks after, the treatment. Patients were divided into a responder and non-responder group according to their respective improvements on the MFT. Data were compared between the two groups. Results Patients with exclusively subcortical stroke, absence of aphasia, the presence of a MEP response, high scores on the Mini-Mental Status Examination, Motricity Index arm score, Functional Independence Measure, and Functional Ambulatory Classification; and a shorter period from stroke onset to rTMS were found to be significantly associated with a response to rTMS. Conclusion The results of this study suggest that rTMS may have a greater effect on upper extremity motor recovery in stroke patients who have a MEP response, suffer an exclusively subcortical stroke, mild paresis, and have good functional status. Applying rTMS early would have additional positive effects in the patients with the identified characteristics. PMID:25932424

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

    PubMed Central

    Tapia, Evelina; Beck, Diane M.

    2014-01-01

    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

  10. Repetitive transcranial magnetic stimulation of the supplementary motor area induces echophenomena.

    PubMed

    Finis, Jennifer; Enticott, Peter G; Pollok, Bettina; Münchau, Alexander; Schnitzler, Alfons; Fitzgerald, Paul B

    2013-01-01

    Apart from tics, echopraxia or echophenomena (EP), i.e., automatic imitation of observed movements, are common in patients with Gilles de la Tourette syndrome (TS). The supplementary motor area (SMA) has been shown to be overactive before the onset of tics in these patients, and it is possible that this area might also play a key role in the generation of echopraxia. We wondered whether EP can also be evoked in healthy controls (HC) by modifying neural activity of this cortical region. To this end, we modulated activity of the SMA in 30 HC by repetitive transcranial magnetic stimulation (rTMS) in an attempt to induce EP. We used both 5 Hz (which can temporarily increase neural activity) and 1 Hz (which disrupts or reduces cortical activity) rTMS. Video clips were presented to 30 HC before and after stimulation. Each clip showed one single movement, either a tic of a TS patient or a spontaneous movement of a HC. During the whole presentation, participants were videotaped in order to detect EP. Video films of participants' responses were rated by two independent raters with respect to EP frequency. Our results reveal an increase of EP following 5 Hz stimulation but no effect following 1 Hz stimulation. This finding implies that the SMA is a relay mediating EP. PMID:23020900

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

    PubMed

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

    2015-04-01

    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

  12. [Transcranial magnetic stimulation (TMS), inhibition processes and attention deficit/hyperactivity disorder (ADHD) - an overview].

    PubMed

    Hoegl, Thomas; Bender, Stephan; Buchmann, Johannes; Kratz, Oliver; Moll, Gunther H; Heinrich, Hartmut

    2014-11-01

    Motor system excitability can be tested by transcranial magnetic stimulation CFMS). In this article, an overview of recent methodological developments and research findings related to attention deficit/hyperactivity disorder (ADHD) is provided. Different TMS parameters that reflect the function of interneurons in the motor cortex may represent neurophysiological markers of inhibition in ADHD, particularly the so-called intracortical inhibition. In children with a high level of hyperactivity and impulsivity, intracortical inhibition was comparably low at rest as shortly before the execution of a movement. TMS-evoked potentials can also be measured in the EEG so that investigating processes of excitability is not restricted to motor areas in future studies. The effects of methylphenidate on motor system excitability may be interpreted in the sense of a 'fine-tuning' with these mainly dopaminergic effects also depending on genetic parameters (DAT1 transporter). A differentiated view on the organization of motor control can be achieved by a combined analysis of TMS parameters and event-related potentials. Applying this bimodal approach, strong evidence for a deviant implementation of motor control in children with ADHD and probably compensatory mechanisms (with involvement of the prefrontal cortex) was obtained. These findings, which contribute to a better understanding of hyperactivity/impulsivity, inhibitory processes and motor control in ADHD as well as the mechanisms of medication, underline the relevance of TMS as a neurophysiological method in ADHD research. PMID:25335520

  13. Transcranial magnetic stimulation of the ventromedial prefrontal cortex impairs theory of mind learning.

    PubMed

    Lev-Ran, S; Shamay-Tsoory, S G; Zangen, A; Levkovitz, Y

    2012-05-01

    Imaging and lesion studies indicate that the prefrontal cortex plays a prominent role in mediating theory of mind (ToM) functioning. Particularly, the ventromedial prefrontal cortex (VMPFC) appears to be involved in mediating ToM functioning. This study utilized slow repetitive transcranial magnetic stimulation (rTMS) over the VMPFC in 13 healthy subjects in order to test whether normal functioning of the VMPFC is necessary for ToM functioning. We found that rTMS to the VMPFC, but not sham-rTMS, significantly disrupted ToM learning. Performance on a control task, not involving affective ToM functioning, was not significantly altered after applying rTMS to the VMPFC or sham-rTMS. In an additional experiment, rTMS to the vertex did not significantly affect ToM learning, confirming specificity of the VMPFC region. These findings indicate that the VMPFC is critical for intact ToM learning and shed further light on the concept and localization of ToM in particular and empathic functioning in general. PMID:21324655

  14. [Transcranial magnetic therapy in the complex treatment of affective disorders in patients with alcoholism].

    PubMed

    Staroverov, A T; Vil'ianov, V B; Ra?gorodski?, Iu M; Rogozina, M A

    2008-01-01

    A main group--32 patients receiving transcranial magnetic therapy (TMT) in addition to the basic treatment (nootrops, hepatoprotectors, vitamins/minerals etc)--was compared to a control group (30 patients) receiving placebo instead of TMT. All patients, aged from 35 to 64 years, had the second stage of alcoholism with illness duration from 4 to 12 years and were in the postabstinent state at the moment of treatment. The TMT course included 10 daily sessions with a 10-20 min exposure. A somatic, neurological and instrumental study, including cardiointervalography, electroencephalography, assessment of autonomic system state and psychometric scales for depression and anxiety, was conducted before, during and after the therapy. The improvement of health, mood and sleep, increase of tolerability to physical loading and reduction of alcohol craving were observed after TMT in 75% of patients in the main group and in 30% in the control one. The improvement of patient's state was correlated with the data of the paraclinical study (electrophysiological parameters of the autonomic nervous system and psychometric scales scores). PMID:18454095

  15. Correlation networks for identifying changes in brain connectivity during epileptiform discharges and transcranial magnetic stimulation.

    PubMed

    Siggiridou, Elsa; Kugiumtzis, Dimitris; Kimiskidis, Vasilios K

    2014-01-01

    The occurrence of epileptiform discharges (ED) in electroencephalographic (EEG) recordings of patients with epilepsy signifies a change in brain dynamics and particularly brain connectivity. Transcranial magnetic stimulation (TMS) has been recently acknowledged as a non-invasive brain stimulation technique that can be used in focal epilepsy for therapeutic purposes. In this case study, it is investigated whether simple time-domain connectivity measures, namely cross-correlation and partial cross-correlation, can detect alterations in the connectivity structure estimated from selected EEG channels before and during ED, as well as how this changes with the application of TMS. The correlation for each channel pair is computed on non-overlapping windows of 1 s duration forming weighted networks. Further, binary networks are derived by thresholding or statistical significance tests (parametric and randomization tests). The information for the binary networks is summarized by statistical network measures, such as the average degree and the average path length. Alterations of brain connectivity before, during and after ED with or without TMS are identified by statistical analysis of the network measures at each state. PMID:25025550

  16. Repetitive transcranial magnetic stimulation over left angular gyrus modulates the predictability gain in degraded speech comprehension.

    PubMed

    Hartwigsen, Gesa; Golombek, Thomas; Obleser, Jonas

    2015-07-01

    Increased neural activity in left angular gyrus (AG) accompanies successful comprehension of acoustically degraded but highly predictable sentences, as previous functional imaging studies have shown. However, it remains unclear whether the left AG is causally relevant for the comprehension of degraded speech. Here, we applied transient virtual lesions to either the left AG or superior parietal lobe (SPL, as a control area) with repetitive transcranial magnetic stimulation (rTMS) while healthy volunteers listened to and repeated sentences with high- versus low-predictable endings and different noise vocoding levels. We expected that rTMS of AG should selectively modulate the predictability gain (i.e., the comprehension benefit from sentences with high-predictable endings) at a medium degradation level. We found that rTMS of AG indeed reduced the predictability gain at a medium degradation level of 4-band noise vocoding (relative to control rTMS of SPL). In contrast, the behavioral perturbation induced by rTMS changed with increased signal quality. Hence, at 8-band noise vocoding, rTMS over AG versus SPL decreased the number of correctly repeated keywords for sentences with low-predictable endings. Together, these results show that the degree of the rTMS interference depended jointly on signal quality and predictability. Our results provide the first causal evidence that the left AG is a critical node for facilitating speech comprehension in challenging listening conditions. PMID:25444577

  17. Innovative treatment approaches in schizophrenia enhancing neuroplasticity: aerobic exercise, erythropoetin and repetitive transcranial magnetic stimulation.

    PubMed

    Wobrock, T; Hasan, A; Falkai, P

    2012-06-01

    Schizophrenia is a brain disorder associated with subtle, but replicable cerebral volume loss mostly prevalent in frontal and temporal brain regions. Post-mortem studies of the hippocampus point to a reduction of the neuropil constituting mainly of synapses associated with changes of molecules mediating plastic responses of neurons during development and learning. Derived from animal studies interventions to enhance neuroplasticity by inducing adult neurogenesis, synaptogenesis, angiogenesis and long-term potentiation (LTP) were developed and the results translated into clinical studies in schizophrenia. Out of these interventions aerobic exercise has been shown to increase hippocampal volume, elevate N-acetyl-aspartate in the hippocampus as neuronal marker, and improve short-term memory in schizophrenia. The hematopoietic growth factor erythropoetin (EPO) is involved in brain development and associated with the production and differentiation of neuronal precursor cells. A first study demonstrated a positive effect of EPO application on cognition in schizophrenia patients. In randomised controlled studies with small sample size, the efficacy of repetitive transcranial magnetic stimulation (rTMS), a biological intervention focussing on the enhancement of LTP, has been shown for the improvement of positive and negative symptoms in schizophrenia,. The putative underlying neurobiological mechanisms of these interventions including the role of neurotrophic factors are outlined and implications for future research regarding neuroprotection strategies to improve schizophrenia are discussed. PMID:22283764

  18. Variability of behavioural responses to transcranial magnetic stimulation: Origins and predictors.

    PubMed

    Nicolo, Pierre; Ptak, Radek; Guggisberg, Adrian G

    2015-07-01

    Transcranial magnetic stimulation (TMS) may modulate the excitability of local cortical stimulation sites and distant functionally interconnected regions for minutes, hours or even days. The effects of TMS suggest that it not only acts on activity of the stimulated area, but also on its connections with remote areas. Due to these properties one of the main rationales for the application of TMS in stroke patients is to improve imbalance in interhemispheric inhibition. However, given that TMS may have excitatory or inhibitory effects the impact of stimulation is not easy to predict. In this review, we discuss the different factors that determine the magnitude and quality of physiological and behavioural responses to TMS. Whether TMS is mainly excitatory or inhibitory not only depends on the parameters of stimulation such as pulse frequency and duration, but also on baseline activity of neural tissue before stimulation, or even on cognitive factors such as attention. A major challenge for the application of TMS as therapy method is to identify predictors of positive effects in individual patients. Neuroimaging studies measuring hemodynamic or electrophysiological responses show that changes in interhemispheric competition or adaptations of functional networks in patients with focal brain lesions may predict the individual response to brain stimulation. Such techniques have the potential to select the most appropriate among different intervention methods for an individual patient. PMID:25619851

  19. Effects of repetitive transcranial magnetic stimulation on recovery of function after spinal cord injury.

    PubMed

    Tazoe, Toshiki; Perez, Monica A

    2015-04-01

    A major goal of rehabilitation strategies after spinal cord injury (SCI) is to enhance the recovery of function. One possible avenue to achieve this goal is to strengthen the efficacy of the residual neuronal pathways. Noninvasive repetitive transcranial magnetic stimulation (rTMS) has been used in patients with motor disorders as a tool to modulate activity of corticospinal, cortical, and subcortical pathways to promote functional recovery. This article reviews a series of studies published during the last decade that used rTMS in the acute and chronic stages of paraplegia and tetraplegia in humans with complete and incomplete SCI. In the studies, rTMS has been applied over the arm and leg representations of the primary motor cortex to target 3 main consequences of SCI: sensory and motor function impairments, spasticity, and neuropathic pain. Although some studies demonstrated that consecutive sessions of rTMS improve aspects of particular functions, other studies did not show similar effects. We discuss how rTMS parameters and postinjury reorganization in the corticospinal tract, motor cortical, and spinal cord circuits might be critical factors in understanding the advantages and disadvantages of using rTMS in patients with SCI. The available data highlight the limited information on the use of rTMS after SCI and the need to further understand the pathophysiology of neuronal structures affected by rTMS to maximize the potential beneficial effects of this technique in humans with SCI. PMID:25175159

  20. Transcranial magnetic stimulation of medial prefrontal cortex modulates implicit attitudes towards food.

    PubMed

    Mattavelli, Giulia; Zuglian, Pablo; Dabroi, Elisa; Gaslini, Guia; Clerici, Massimo; Papagno, Costanza

    2015-06-01

    The medial prefrontal cortex (mPFC) is known to be associated with food representation and monitoring of eating behaviour, but the neural mechanisms underlying attitudes towards food are still unclear. Transcranial magnetic stimulation (TMS) was used in combination with the implicit association test (IAT) to investigate the causal role of mPFC in controlling implicit food evaluation in healthy volunteers. Participants performed an IAT on tasty and tasteless food to test TMS interaction with food evaluation. Moreover, IATs assessing self-related concepts and attitude towards flowers and insects were carried out to control whether TMS could also affect self-representation or, more in general, the cognitive mechanisms required by the IAT. TMS was applied over mPFC; the left parietal cortex (lPA) was also stimulated as control site. Results revealed that mPFC-TMS selectively affected IAT on food, increasing implicit preference for tasty than tasteless food, only in a subgroup of participants who did not show extreme explicit evaluation for tasty and tasteless food. This demonstrates that mPFC has a critical causal role in monitoring food preference and highlights the relevance of considering individual differences in studying food representation and neural mechanisms associated with eating behaviour. PMID:25620531

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

    PubMed

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

    2013-09-01

    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

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

    PubMed

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

    2013-01-01

    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

  3. The emerging role for repetitive transcranial magnetic stimulation in optimizing the treatment of adolescent depression.

    PubMed

    Croarkin, Paul E; Wall, Christopher A; McClintock, Shawn M; Kozel, Frank Andrew; Husain, Mustafa M; Sampson, Shirlene M

    2010-12-01

    Major depressive disorder (MDD) in adolescents is a common illness and significant public health problem. Treatment is challenging because of recurrences and limited modalities. Selective serotonin reuptake inhibitors and cognitive behavioral therapy are considered the standard of care in severe or treatment-resistant MDD in this age group. However, responses to these interventions are often suboptimal. A growing body of research supports the efficacy of repetitive transcranial magnetic stimulation (rTMS) for the treatment of MDD in adults. Induced seizures are a primary safety concern, although this is rare with appropriate precautions. There is, however, limited experience with rTMS as a therapeutic intervention for adolescent psychiatric disturbances. This review will summarize the rTMS efficacy and safety data in adults and describe all published experience with adolescent MDD. Applications in other adolescent psychiatric illnesses such as schizophrenia and attention-deficit/hyperactivity disorder are reviewed. Safety and ethical issues are paramount with investigational treatments in adolescent psychiatric illnesses. However, further research with rTMS in adolescent MDD is imperative to establish standards for optimal stimulation site, treatment parameters, and its role in treatment algorithms. These may diverge from adult data. Early intervention with neuromodulation could also hold the promise of addressing the developmental course of dysfunctional neurocircuitry. PMID:20418774

  4. Repetitive transcranial magnetic stimulation: a putative add-on treatment for major depression in elderly patients.

    PubMed

    Mosimann, Urs P; Schmitt, Wolfgang; Greenberg, Benjamin D; Kosel, Markus; Müri, René M; Berkhoff, Magdalena; Hess, Christian W; Fisch, Hans U; Schlaepfer, Thomas E

    2004-04-30

    Repetitive transcranial magnetic stimulation (rTMS) is a recent putative treatment for affective disorders. Several studies have demonstrated antidepressant effects of rTMS in younger patients; we aimed to assess its effect in older outpatients with treatment-resistant major depression. Twenty-four outpatients (mean age=62 years, S.D.=12) with major depression were randomized for sham or real stimulation and received 10 daily rTMS sessions (20 Hz, 2-s trains, 28-s intertrain intervals, 100% of motor threshold) in addition to the antidepressant medication. For sham stimulation, the coil was tilted 90 degrees. Depression severity was assessed using the Hamilton Depression Rating Scale, the Beck Depression Inventory, items from the NIMH self-rated symptom scale, and a visual analog depression scale. Mini-Mental Status Examination performance, memory, and executive and attentional functions were measured to control for cognitive side effects. Depression ratings revealed significant antidepressant effects within 2 weeks in both sham and real stimulation groups; however, there were no between-group differences. Treatment with rTMS was safe; adverse events were rare and not more prevalent in either group, and cognitive assessment did not show any deterioration. We were unable to demonstrate any additional antidepressant effects of real stimulation in elderly patients with treatment-resistant major depression. Therapeutic effects of rTMS in this clinically challenging patient group remain to be demonstrated. PMID:15123391

  5. Transcranial magnetic stimulation and brain atrophy: a computer-based human brain model study

    PubMed Central

    Eden, Uri; Fregni, Felipe; Valero-Cabre, Antoni; Ramos-Estebanez, Ciro; Pronio-Stelluto, Valerie; Grodzinsky, Alan; Zahn, Markus; Pascual-Leone, Alvaro

    2012-01-01

    This paper is aimed at exploring the effect of cortical brain atrophy on the currents induced by transcranial magnetic stimulation (TMS). We compared the currents induced by various TMS conditions on several different MRI derived finite element head models of brain atrophy, incorporating both decreasing cortical volume and widened sulci. The current densities induced in the cortex were dependent upon the degree and type of cortical atrophy and were altered in magnitude, location, and orientation when compared to healthy head models. Predictive models of the degree of current density attenuation as a function of the scalp-to-cortex distance were analyzed, concluding that those which ignore the electromagnetic field–tissue interactions lead to inaccurate conclusions. Ultimately, the precise site and population of neural elements stimulated by TMS in an atrophic brain cannot be predicted based on healthy head models which ignore the effects of the altered cortex on the stimulating currents. Clinical applications of TMS should be carefully considered in light of these findings. PMID:18193208

  6. Transcranial Magnetic Stimulation to Address Mild Cognitive Impairment in the Elderly: A Randomized Controlled Study

    PubMed Central

    Drumond Marra, Hellen Livia; Myczkowski, Martin Luiz; Maia Memória, Cláudia; Arnaut, Débora; Leite Ribeiro, Philip; Sardinha Mansur, Carlos Gustavo; Lancelote Alberto, Rodrigo; Boura Bellini, Bianca; Alves Fernandes da Silva, Adriano; Tortella, Gabriel; Ciampi de Andrade, Daniel; Teixeira, Manoel Jacobsen; Forlenza, Orestes Vicente; Marcolin, Marco Antonio

    2015-01-01

    Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique with potential to improve memory. Mild cognitive impairment (MCI), which still lacks a specific therapy, is a clinical syndrome associated with increased risk of dementia. This study aims to assess the effects of high-frequency repetitive TMS (HF rTMS) on everyday memory of the elderly with MCI. We conducted a double-blinded randomized sham-controlled trial using rTMS over the left dorsolateral prefrontal cortex (DLPFC). Thirty-four elderly outpatients meeting Petersen's MCI criteria were randomly assigned to receive 10 sessions of either active TMS or sham, 10?Hz rTMS at 110% of motor threshold, 2,000 pulses per session. Neuropsychological assessment at baseline, after the last session (10th) and at one-month follow-up, was applied. ANOVA on the primary efficacy measure, the Rivermead Behavioural Memory Test, revealed a significant group-by-time interaction (p = 0.05), favoring the active group. The improvement was kept after one month. Other neuropsychological tests were heterogeneous. rTMS at 10?Hz enhanced everyday memory in elderly with MCI after 10 sessions. These findings suggest that rTMS might be effective as a therapy for MCI and probably a tool to delay deterioration.

  7. Corticospinal excitability during action observation in task-specific dystonia: a transcranial magnetic stimulation study.

    PubMed

    Fiorio, M; Zhang, W; Bresciani, M C; Rodi, G; Bertolasi, L; Gambarin, M; Tinazzi, M

    2010-11-24

    Observation of actions performed by other individuals activates the onlooker's motor system in a way similar to real movement execution. The functioning of this mechanism in the pathological domain is not clear yet. The aim of this study was to explore whether action observation activates the motor system of patients affected by a task-specific form of dystonia, such as writer's cramp. Transcranial magnetic stimulation was applied over the primary motor cortex and motor evoked potentials were recorded from hand (FDI and ADM) and forearm (FCR) muscles at baseline and during observation of actions (grasping and writing) or images. Writing actions could be performed with healthy or dystonic movement patterns. Results showed a highly specific and reversed pattern of activation in the FDI muscle of the two groups. Differences between the two writing conditions were significantly opposite in the two groups: control subjects had higher activation during observation of the dystonic compared to the healthy action, whereas in patients observation of the healthy writing led to higher activation than the dystonic writing. This opposite corticospinal modulation might be explained by a different self-attribution of the observed actions in the two groups. PMID:20837104

  8. Frequency-dependent effects of contralateral repetitive transcranial magnetic stimulation on penicillin-induced seizures.

    PubMed

    Lin, Ching-Yi; Li, Kevin; Franic, Linda; Gonzalez-Martinez, Jorge; Lin, Vernon W; Najm, Imad; Lee, Yu-Shang

    2014-09-18

    Transcranial magnetic stimulation (TMS) has been shown to modulate multiple brain functions, warranting further exploration in clinical applications. TMS treatment for epilepsy is particularly promising because of its anti-convulsive capabilities. However, TMS has been found to both inhibit and facilitate various experimental and clinical seizures, depending on the TMS parameters used. Repetitive TMS (rTMS) pulse frequency is recognized as one of the most influential parameters and thus was investigated in this study at 1, 5 and 10 Hz for its effects on a rat model of penicillin-induced seizures. High-dose penicillin-induced seizures were characterized by a combination of myoclonic and tonic-clonic (GTC) seizures. rTMS effects were analyzed with intracranial electroencephalographic (iEEG) data and video-captured behaviors. Animals treated with 1 and 5 Hz consistently showed evidence of anti-convulsive properties in their iEEG-based seizure profiles when compared to sham rTMS treatment. In contrast, data from 10 Hz rTMS suggested facilitative characteristics. Our results showed that 5 Hz rTMS consistently outperformed 1 Hz rTMS in seizure suppression. This re-emphasizes the importance in accurately characterizing TMS effects on seizure suppression due to the heterogeneous nature of seizures. Thus, finely tuned TMS treatment has great potential to become a powerful asset in combating epilepsy. PMID:24937795

  9. Citalopram for continuation therapy following repetitive transcranial magnetic stimulation (rTMS) in vascular depression

    PubMed Central

    Tenev, Veselin; Robinson, Robert G.; Jorge, Ricardo E.

    2009-01-01

    Objectives We previously reported that repetitive transcranial magnetic stimulation (rTMS) produced a response rate of 39.4% among 62 patients with treatment resistant vascular depression. The current study was undertaken to assess the outcome of continuation therapy to prevent relapse among these patients during 9 weeks after completion of rTMS. Design Patients were randomly assigned to 18,000 pulses of rTMS given over 3 weeks or sham treatment using double blind methods. Following rTMS, all patients were given 20 mg per day of citalopram for 9 weeks and reevaluated at 3, 6 and 9 weeks. Setting Outpatient continuation treatment trial. Participants Patients with vascular depression (n=62), as determined by MRI hyperintensities and/or 3 or more clinical risk factors for vascular disease without other major medical illness, were recruited. They had onset of major depression after age 50 and failed at least one trial of antidepressants. Intervention Following rTMS or sham treatment, all treatment responders were given citalopram for 9 weeks. Results Among the 33 patients given rTMS, 13 responded (i.e. >50% decline in Hamilton Depression Scale score). Of these 13, all completed the 9 weeks of continuation treatment. There were 9 patients who continued to be responders and 4 who had a relapse of depression. Conclusion More effective methods are needed to treat elderly patients with treatment resistant vascular depression and to prevent relapse among treatment responders. PMID:19625785

  10. Effect of Repetitive Transcranial Magnetic Stimulation According to the Stimulation Site in Stroke Patients With Dysphagia

    PubMed Central

    Lee, Jong Hwa; Kim, Sang Beom; Lee, Kyeong Woo; Lee, Sook Joung

    2015-01-01

    Objective To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) according to the stimulation site in subacute stroke patients with dysphagia. Methods This study was designed as a matched comparative study. Twenty-four patients who had dysphagia after ischemic stroke were recruited, and they were divided into two groups after matching for age and stroke lesion. The patients in group A received rTMS over the brain cortex where motor evoked potential (MEP) was obtained from the suprahyoid muscle. Group B received rTMS over the brain cortex where MEP was obtained from the abductor pollicis brevis muscle. rTMS was performed at 110% of MEP threshold, 10 Hz frequency for 10 seconds, and then repeated every minute for 10 minutes. Dysphagia status was measured by the Functional Dysphagia Scale (FDS), the Penetration-Aspiration Scale (PAS), and the Dysphagia Outcome and Severity Scale (DOSS) using the results of a videofluoroscopic swallowing study. These evaluations were measured before, immediately, and 4 weeks after rTMS. Results Group A showed significant improvement compared to group B in the DOSS score immediately and 4 weeks after rTMS. There were no significant differences in the changes of FDS and PAS scores between groups A and B immediately and 4 weeks after rTMS. Conclusion rTMS over a hot spot for the suprahyoid muscle caused more improvement in swallowing function when compared to that over the interconnected site.

  11. Stochastic resonance effects reveal the neural mechanisms of transcranial magnetic stimulation

    PubMed Central

    Schwarzkopf, Dietrich Samuel; Silvanto, Juha; Rees, Geraint

    2011-01-01

    Transcranial magnetic stimulation (TMS) is a popular method for studying causal relationships between neural activity and behavior. However its mode of action remains controversial, and so far there is no framework to explain its wide range of facilitatory and inhibitory behavioral effects. While some theoretical accounts suggests that TMS suppresses neuronal processing, other competing accounts propose that the effects of TMS result from the addition of noise to neuronal processing. Here we exploited the stochastic resonance phenomenon to distinguish these theoretical accounts and determine how TMS affects neuronal processing. Specifically, we showed that online TMS can induce stochastic resonance in the human brain. At low intensity, TMS facilitated the detection of weak motion signals but with higher TMS intensities and stronger motion signals we found only impairment in detection. These findings suggest that TMS acts by adding noise to neuronal processing, at least in an online TMS protocol. Importantly, such stochastic resonance effects may also explain why TMS parameters that under normal circumstances impair behavior, can induce behavioral facilitations when the stimulated area is in an adapted or suppressed state. PMID:21368025

  12. Lateralized effect of rapid-rate transcranial magnetic stimulation of the prefrontal cortex on mood.

    PubMed

    Pascual-Leone, A; Catalá, M D; Pascual-Leone Pascual, A

    1996-02-01

    We studied the effects of rapid-rate transcranial magnetic stimulation (rTMS) of different scalp positions on mood. Ten normal volunteers rated themselves before and after rTMS on five analog scales labeled "Tristeza" (Sadness), "Ansiedad" (Anxiety), "Alegria" (Happiness), "Cansancio" (Tiredness), and "Dolor/Malestar" (Pain/Discomfort). rTMS was applied to the right lateral prefrontal, left prefrontal, or midline frontal cortex in trains of 5 seconds' duration at 10 Hz and 110% of the subject's motor threshold intensity. Each stimulation position received 10 trains separated by a 25-second pause. No clinically apparent mood changes were evoked by rTMS to any of the scalp positions in any subject. However, left prefrontal rTMS resulted in a significant increase in the Sadness ratings (Tristeza) and a significant decrease in the Happiness ratings ("Alegria") as compared with right prefrontal and midfrontal cortex stimulation. These results show differential effects of rTMS of left and right prefrontal cortex stimulation on mood and illustrate the lateralized control of mood in normal volunteers. PMID:8614521

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

    PubMed Central

    Salinas, Felipe S.; Szabó, C. Ákos; Zhang, Wei; Jones, Lisa; Leland, M. Michelle; Wey, Hsiao-Ying; Duong, Timothy Q.; Fox, Peter T.; Narayana, Shalini

    2011-01-01

    Transcranial magnetic stimulation (TMS) has well-established applications in basic neuroscience and promising applications in neurological and psychiatric disorders. However the underlying mechanisms of TMS-induced alterations in brain function are not well understood. As a result, treatment design parameters are determined ad hoc and not informed by any coherent theory or model. Once the mechanisms underlying TMS’s modulatory effects on brain systems are better understood and modeled, TMS’s potential as a therapeutic and/or investigative tool will be more readily explored and exploited. An animal model is better suited to study different TMS variables, therefore we developed a baboon model to facilitate testing of some of the current theoretical models of TMS interactions with brain regions. We have demonstrated the feasibility of this approach by successfully imaging cerebral blood flow (CBF) changes with H215O positron emission tomography imaging during high-frequency, suprathreshold repetitive TMS in the primary motor cortex of five healthy, adult baboons. PMID:21664276

  14. [Computer modelling of electroconvulsive treatment and transcranial magnetic stimulation--an explanation of poor efficacy of the magnetic method].

    PubMed

    Zyss, Tomasz; Krawczyk, Andrzej; Zieba, Andrzej; Dudek, Dominika; Hese, Robert T; Drzyma?a, Pawe?; Wiak, S?awomir; Sawicki, Bartosz; Starzy?ski, Jacek; Szmur?o, Robert; Wincenciak, Stanis?aw

    2010-01-01

    With help of informatics technology it is possible to simulate various physiological processes in virtual models of biological structures. In a created realistic model of the human head we made some comparative investigations over physical phenomena accompanying the electroconvulsive treatment ECT and transcranial magnetic stimulation TMS--two methods with confirmed (ECT) or presumable (TMS) antidepressant efficacy. The present investigations are a continuation of the earlier conducted study in the simple spherical model of the head. Investigations confirmed, that magnetic stimulation TMS generates a considerably weaker current flow in the brain than it is present in electroconvulsive technique. Applying of such weak stimulation in modus,,at haphazard", i.e. on the brain area which does not need to be metabolically disturbed in this patient--cannot cause an antidepressant effect at all. The results of the investigations explain not only the safety of the magnetic method, but the weak effectiveness of this method. The authors propose some methods for improvement of TMS efficacy. PMID:21449167

  15. Extracting visual evoked potentials from EEG data recorded during fMRI-guided transcranial magnetic stimulation.

    PubMed

    Sadeh, Boaz; Yovel, Galit

    2014-01-01

    Transcranial Magnetic Stimulation (TMS) is an effective method for establishing a causal link between a cortical area and cognitive/neurophysiological effects. Specifically, by creating a transient interference with the normal activity of a target region and measuring changes in an electrophysiological signal, we can establish a causal link between the stimulated brain area or network and the electrophysiological signal that we record. If target brain areas are functionally defined with prior fMRI scan, TMS could be used to link the fMRI activations with evoked potentials recorded. However, conducting such experiments presents significant technical challenges given the high amplitude artifacts introduced into the EEG signal by the magnetic pulse, and the difficulty to successfully target areas that were functionally defined by fMRI. Here we describe a methodology for combining these three common tools: TMS, EEG, and fMRI. We explain how to guide the stimulator's coil to the desired target area using anatomical or functional MRI data, how to record EEG during concurrent TMS, how to design an ERP study suitable for EEG-TMS combination and how to extract reliable ERP from the recorded data. We will provide representative results from a previously published study, in which fMRI-guided TMS was used concurrently with EEG to show that the face-selective N1 and the body-selective N1 component of the ERP are associated with distinct neural networks in extrastriate cortex. This method allows us to combine the high spatial resolution of fMRI with the high temporal resolution of TMS and EEG and therefore obtain a comprehensive understanding of the neural basis of various cognitive processes. PMID:24893706

  16. Static field influences on transcranial magnetic stimulation: Considerations for TMS in the scanner environment

    PubMed Central

    Yau, Jeffrey M.; Jalinous, Reza; Cantarero, Gabriela L.; Desmond, John E.

    2014-01-01

    Background: Transcranial magnetic stimulation (TMS) can be combined with functional magnetic resonance imaging (fMRI) to simultaneously manipulate and monitor human cortical responses. Although tremendous efforts have been directed at characterizing the impact of TMS on image acquisition, the influence of the scanner’s static field on the TMS coil has received limited attention. Objective/Hypothesis: The aim of this study was to characterize the influence of the scanner’s static field on TMS. We hypothesized that spatial variations in the static field could account for TMS field variations in the scanner environment. Methods: Using a MRI-compatible TMS coil, we estimated TMS field strengths based on TMS-induced voltage changes measured in a search coil. We compared peak field strengths obtained with the TMS coil positioned at different locations (B0 field vs fringe field) and orientations in the static field. We also measured the scanner’s static field to derive a field map to account for TMS field variations. Results: TMS field strength scaled depending on coil location and orientation with respect to the static field. Larger TMS field variations were observed in fringe field regions near the gantry as compared to regions inside the bore or further removed from the bore. The scanner’s static field also exhibited the greatest spatial variations in fringe field regions near the gantry. Conclusions: The scanner’s static field influences TMS fields and spatial variations in the static field correlate with TMS field variations. TMS field variations can be minimized by delivering TMS in the bore or outside of the 0 - 70 cm region from the bore entrance. PMID:24656916

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

    PubMed Central

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

    2014-01-01

    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

  18. How does transcranial magnetic stimulation modify neuronal activity in the brain? Implications for studies of cognition.

    PubMed

    Siebner, Hartwig R; Hartwigsen, Gesa; Kassuba, Tanja; Rothwell, John C

    2009-10-01

    Transcranial magnetic stimulation (TMS) uses a magnetic field to "carry" a short lasting electrical current pulse into the brain where it stimulates neurones, particularly in superficial regions of cerebral cortex. TMS can interfere with cognitive functions in two ways. A high intensity TMS pulse causes a synchronised high frequency burst of discharge in a relatively large population of neurones that is terminated by a long lasting GABAergic inhibition. The combination of artificial synchronisation of activity followed by depression effectively disrupts perceptual, motor and cognitive processes in the human brain. This transient neurodisruption has been termed a "virtual lesion". Smaller intensities of stimulation produce less activity; in such cases, cognitive operations can probably continue but are disrupted because of the added noisy input from the TMS pulse. It is usually argued that if a TMS pulse affects performance, then the area stimulated must provide an essential contribution to behaviour being studied. However, there is one exception to this: the pulse could be applied to an area that is not involved in the task but which has projections to the critical site. Activation of outputs from the site of stimulation could potentially disrupt processing at the distant site, interfering with behaviour without having any involvement in the task. A final important feature of the response to TMS is "context dependency", which indicates that the response depends on how excitable the cortex is at the time the stimulus is applied: if many neurones are close to firing threshold then the more of them are recruited by the pulse than at rest. Many studies have noted this context-dependent modulation. However, it is often assumed that the excitability of an area has a simple relationship to activity in that area. We argue that this is not necessarily the case. Awareness of the problem may help resolve some apparent anomalies in the literature. PMID:19371866

  19. Magnetic Field Distribution and Application of a Transcranial Magnetic Stimulation for Drug Addicts

    Microsoft Academic Search

    Yu Chang; Miao Song; Bin Gao; Ningning Chen; Ling Li; Hongxing Wang

    2009-01-01

    This article introduces the property of magnetic field distribution and application of TMS developed by BJUT. The TMS generates time-varying magnetic field to stimulate the particular area in human brain. To obtain the distribution of magnetic density, we carried out survey by utilizing a Gauss meter, from three aspects: the distribution of magnetic density in axial direction, in radial direction

  20. Repetitive transcranial magnetic stimulation (rTMS): a possible novel therapeutic approach to dementia with Lewy bodies.

    PubMed

    Liang, Xuemei; Liu, Kezhi; Guo, Lanting

    2010-05-01

    Dementia with Lewy bodies (DLB) is characterized clinically by widespread cognitive loss, visual hallucinations, depression, anxiety and extrapyramidal signs (EPS). DLB is sensitive to typical neuroleptics. Repetitive transcranial magnetic stimulation (rTMS) has been studied as a potential treatment in many neurological disorders, which has been proved to have positive effect on a variety of cognitive functions, hallucinations of schizophrenia, major depression, anxiety, the Parkinson's disease. This report proposes that rTMS may represent an alternative strategy for the treatment of dementia with Lewy bodies. PMID:20006914

  1. Age-Related Changes in Motor Cortical Representation and Interhemispheric Interactions: A Transcranial Magnetic Stimulation Study

    PubMed Central

    Coppi, Elisabetta; Houdayer, Elise; Chieffo, Raffaella; Spagnolo, Francesca; Inuggi, Alberto; Straffi, Laura; Comi, Giancarlo; Leocani, Letizia

    2014-01-01

    To better understand the physiological mechanisms responsible for the differential motor cortex functioning in aging, we used transcranial magnetic stimulation to investigate interhemispheric interactions and cortical representation of hand muscles in the early phase of physiological aging, correlating these data with participants’ motor abilities. Right-handed healthy subjects were divided into a younger group (n?=?15, mean age 25.4?±?1.9?years old) and an older group (n?=?16, mean age 61.1?±?5.1?years old). Activity of the bilateral abductor pollicis brevis (APB) and abductor digiti minimi (ADM) was recorded. Ipsilateral silent period (ISP) was measured in both APBs. Cortical maps of APB and ADM were measured bilaterally. Mirror movements (MM) were recorded during thumb abductions. Motor abilities were tested using Nine Hole Peg Test, finger tapping, and grip strength. ISP was reduced in the older group on both sides, in terms of duration (p?=?0.025), onset (p?=?0.029), and area (p?=?0.008). Resting motor threshold did not differ between groups. APB and ADM maps were symmetrical in the younger group, but were reduced on the right compared to the left hemisphere in the older group (p?=?0.008). The APB map of the right hemisphere was reduced in the older group compared to the younger (p?=?0.021). Older subjects showed higher frequency of MM and worse motor abilities (p?

  2. The effects of repetitive transcranial magnetic stimulation on proliferation and differentiation of neural stem cells

    PubMed Central

    Abbasnia, Keramatollah; Ghanbari, Amir; Abedian, Mehrnaz; Ghanbari, Ali; Sharififar, Sharareh

    2015-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is a new method for treating many neurological conditions; however, the exact therapeutic mechanisms behind rTMS-induced plasticity are still unknown. Neural stem and progenitor cells (NS/PCs) are active players in brain regeneration and plasticity but their behavior in the context of rTMS therapy needs further elucidation. We aimed to evaluate the effects of rTMS on proliferation and differentiation of NS/PCs in the subventricular zone (SVZ) of adult mouse brain. Adult male mice (n=30) were divided into rTMS (1-Hz and 30-Hz) and sham groups and treated for 7 or 14 consecutive days. Harvested NS/PCs from the SVZ were cultured in the neurosphere assay for 8 days and the number and size of the resulting neurospheres as well as their in vitro differentiation capacity were evaluated. After one week of rTMS treatment at 1-Hz and 30-Hz compared with sham stimulation, the mean neurosphere forming frequency per brain was not different while this measure significantly increased after two weeks (P<0.05). The mean neurosphere diameter in 1-Hz treatment paradigm was significantly larger compared with sham stimulation at both 1 and 2 weeks. In contrast, 30-Hz treatment paradigm resulted in significantly larger neurospheres only after 2 weeks. Importantly, rTMS treatment at both frequencies increased neuronal differentiation of the harvested NS/PCs. Furthermore, one week in vitro rTMS treatment of NS/PCs with both 1-Hz and 30-Hz increased NS/PCs proliferation and neuronal differentiation. It is concluded that both 1-Hz and 30-Hz rTMS treatment increase NS/PCs proliferation and neuronal differentiation. PMID:26140221

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

    PubMed Central

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

    2014-01-01

    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

  4. The Effect of 10 Hz Repetitive Transcranial Magnetic Stimulation of Posterior Parietal Cortex on Visual Attention

    PubMed Central

    Dombrowe, Isabel; Juravle, Georgiana; Alavash, Mohsen; Gießing, Carsten; Hilgetag, Claus C.

    2015-01-01

    Repetitive transcranial magnetic stimulation (rTMS) of the posterior parietal cortex (PPC) at frequencies lower than 5 Hz transiently inhibits the stimulated area. In healthy participants, such a protocol can induce a transient attentional bias to the visual hemifield ipsilateral to the stimulated hemisphere. This bias might be due to a relatively less active stimulated hemisphere and a relatively more active unstimulated hemisphere. In a previous study, Jin and Hilgetag (2008) tried to switch the attention bias from the hemifield ipsilateral to the hemifield contralateral to the stimulated hemisphere by applying high frequency rTMS. High frequency rTMS has been shown to excite, rather than inhibit, the stimulated brain area. However, the bias to the ipsilateral hemifield was still present. The participants’ performance decreased when stimuli were presented in the hemifield contralateral to the stimulation site. In the present study we tested if this unexpected result was related to the fact that participants were passively resting during stimulation rather than performing a task. Using a fully crossed factorial design, we compared the effects of high frequency rTMS applied during a visual detection task and high frequency rTMS during passive rest on the subsequent offline performance in the same detection task. Our results were mixed. After sham stimulation, performance was better after rest than after task. After active 10 Hz rTMS, participants’ performance was overall better after task than after rest. However, this effect did not reach statistical significance. The comparison of performance after rTMS with task and performance after sham stimulation with task showed that 10 Hz stimulation significantly improved performance in the whole visual field. Thus, although we found a trend to better performance after rTMS with task than after rTMS during rest, we could not reject the hypothesis that high frequency rTMS with task and high frequency rTMS during rest equally affect performance. PMID:25970438

  5. Interaction between vestibulo-spinal and corticospinal systems: a combined caloric and transcranial magnetic stimulation study.

    PubMed

    Guzman-Lopez, J; Buisson, Y; Strutton, P H; Bronstein, A M

    2011-09-01

    We investigated the interaction between vestibular and corticospinal stimuli in 8 healthy volunteers. Vestibular stimulation was induced with unilateral ear caloric irrigation (30°C) with subjects supine. Single transcranial magnetic stimulation (TMS) pulses were delivered (double-cone coil, intensities 60-75% maximal output) every 10-20 s during vestibular activation and during baseline. Bilateral surface electromyography (EMG) from splenius capitis, sternocleidomastoid (SCM), obliquus externus abdominis, vastus lateralis, biceps femoris (BF), tibialis anterior and peroneus longus was obtained. During whole-body maximal rotatory voluntary isometric contraction (MRVC), only SCM and BF displayed EMG activation/inhibition patterns indicating axial rotatory action. TMS-induced motor evoked potentials (MEPs) after caloric irrigation revealed that only SCM showed consistent vestibular-mediated excitation/inhibition responses, i.e. an increase in MEP area contralateral to the irrigation and a decrease in MEP area ipsilaterally (+12.7 and -6.3% of the MRVC, respectively). A putative head turn induced by this SCM activity pattern would be in the same direction of the slow-phase eye movement. EMG in the 100 ms preceding TMS showed muscle tone values of approximately 10% of MRVC. After caloric irrigation, these values increased by ca. 2% for all muscles bilaterally and hence cannot explain the direction-specific SCM MEP changes. Thus, SCM MEPs show caloric-induced amplitude modulation indicating that SCM is under both horizontal semicircular canal and corticospinal control. This vestibular modulation of corticospinal SCM control likely occurs at cortical levels. The direction of the MEP modulation indicates a directional coupling between vestibularly induced head and eye movements. PMID:21805198

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed

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

    2014-04-01

    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

  8. Repeatability of functional anisotropy in navigated transcranial magnetic stimulation - coil-orientation versus response.

    PubMed

    Kallioniemi, Elisa; Könönen, Mervi; Julkunen, Petro

    2015-06-17

    Transcranial magnetic stimulation (TMS) can be used for evaluating the function of motor pathways. According to the principles of electromagnetism and electrophysiology, TMS activates those neurons that are suitably oriented with respect to the TMS-induced electric field. We hypothesized that TMS could potentially be able to evaluate the neuronal structure, although until now, this putative application has not been exploited. We have developed a TMS-based method to evaluate the function and structure of the motor cortex concurrently in a quantitative manner. This method produced a measure, the anisotropy index (AI), which is based on the motor-evoked potentials induced at different coil orientations. The AI was demonstrated to exhibit an association with both motor cortex excitability and neuronal structure. In the present study, we evaluated the repeatability (intrasession and intersession) of AI in three consecutive measurements. In addition, we studied the repeatability of the optimal coil angle in inducing motor-evoked potentials. Two of the measurements were conducted on the same stimulation target and the third on a remapped target. The coefficient of repeatability of the AI was 0.022 for intrasession and 0.040 for intersession assessments. For the optimal stimulation angle, the coefficients of repeatability were 3.7° and 5.1°, respectively. Both the AI and the optimal stimulation angle demonstrated good repeatability (Cronbach's ?>0.760). In conclusion, the results indicate that the AI can provide a reliable estimation of local functional anisotropy changes under conditions affecting the cortex, such as during stroke or focal dysplasia. PMID:26011386

  9. [Possibilities of transcranial magnetic therapy and color and rhythm therapy in rehabilitation of ischemic stroke].

    PubMed

    Sholomov, I I; Cherevashchenko, L A; Suprunov, O V; Ra?gorondski?, Iu M

    2009-01-01

    One hundred and sixteen post-stroke patients were studied in the early rehabilitation period. All patients were divided into 4 groups: 3 main and 1 control groups. Three main groups (87 patients) received transcranial magnetic therapy (TMT) and/or color and rhythm therapy (CRT) along with traditional treatment and the control group (29 patients) received only basic therapy. TMT was conducted using bitemporal technique, running regime with modulation frequency 1-10 Hz. In CRT, the alternating stimulation of the right and left eye with green and/or blue color with a period of 2-4 s and duration of luminescence 1s was applied. Each of 3 main groups received 2 treatment sessions with an interval of 1,5 month (1st - TMT, 2nd - CRT, 3rd - TMT + CRT). After the treatment, the marked positive changes were seen in all main groups, in particular in group 3. The improvement of neurologic symptoms on the B. Lindmark scale was higher by 9,5% in group 3 compared to the control one, on the Barthel index - by 8,8%, on MMSE and A. Luria and Schulte test - by 5,4 and 14,3%, respectively. Rheographic and encephalographic study revealed the significant improvement of hemodynamics and alpha-rhythm differentiation, decrease of patients with dysrhythmia by 14,6% in group 3 as compared to the control group. The best results were seen in the combination of TMT and CRT, TMT exerted a higher effect on the hemodynamics and CRT - on the psychoemotional state. Both therapies were well tolerated and had no side-effects. PMID:19672234

  10. 5 Hz repetitive transcranial magnetic stimulation over the ipsilesional sensory cortex enhances motor learning after stroke

    PubMed Central

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

    2014-01-01

    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

  11. Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS).

    PubMed

    Lefaucheur, Jean-Pascal; André-Obadia, Nathalie; Antal, Andrea; Ayache, Samar S; Baeken, Chris; Benninger, David H; Cantello, Roberto M; Cincotta, Massimo; de Carvalho, Mamede; De Ridder, Dirk; Devanne, Hervé; Di Lazzaro, Vincenzo; Filipovi?, Saša R; Hummel, Friedhelm C; Jääskeläinen, Satu K; Kimiskidis, Vasilios K; Koch, Giacomo; Langguth, Berthold; Nyffeler, Thomas; Oliviero, Antonio; Padberg, Frank; Poulet, Emmanuel; Rossi, Simone; Rossini, Paolo Maria; Rothwell, John C; Schönfeldt-Lecuona, Carlos; Siebner, Hartwig R; Slotema, Christina W; Stagg, Charlotte J; Valls-Sole, Josep; Ziemann, Ulf; Paulus, Walter; Garcia-Larrea, Luis

    2014-11-01

    A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the pain and the antidepressant effect of HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC). A Level B recommendation (probable efficacy) is proposed for the antidepressant effect of low-frequency (LF) rTMS of the right DLPFC, HF-rTMS of the left DLPFC for the negative symptoms of schizophrenia, and LF-rTMS of contralesional M1 in chronic motor stroke. The effects of rTMS in a number of indications reach level C (possible efficacy), including LF-rTMS of the left temporoparietal cortex in tinnitus and auditory hallucinations. It remains to determine how to optimize rTMS protocols and techniques to give them relevance in routine clinical practice. In addition, professionals carrying out rTMS protocols should undergo rigorous training to ensure the quality of the technical realization, guarantee the proper care of patients, and maximize the chances of success. Under these conditions, the therapeutic use of rTMS should be able to develop in the coming years. PMID:25034472

  12. The effects of repetitive transcranial magnetic stimulation on proliferation and differentiation of neural stem cells.

    PubMed

    Abbasnia, Keramatollah; Ghanbari, Amir; Abedian, Mehrnaz; Ghanbari, Ali; Sharififar, Sharareh; Azari, Hassan

    2015-06-01

    Repetitive transcranial magnetic stimulation (rTMS) is a new method for treating many neurological conditions; however, the exact therapeutic mechanisms behind rTMS-induced plasticity are still unknown. Neural stem and progenitor cells (NS/PCs) are active players in brain regeneration and plasticity but their behavior in the context of rTMS therapy needs further elucidation. We aimed to evaluate the effects of rTMS on proliferation and differentiation of NS/PCs in the subventricular zone (SVZ) of adult mouse brain. Adult male mice (n=30) were divided into rTMS (1-Hz and 30-Hz) and sham groups and treated for 7 or 14 consecutive days. Harvested NS/PCs from the SVZ were cultured in the neurosphere assay for 8 days and the number and size of the resulting neurospheres as well as their in vitro differentiation capacity were evaluated. After one week of rTMS treatment at 1-Hz and 30-Hz compared with sham stimulation, the mean neurosphere forming frequency per brain was not different while this measure significantly increased after two weeks (P<0.05). The mean neurosphere diameter in 1-Hz treatment paradigm was significantly larger compared with sham stimulation at both 1 and 2 weeks. In contrast, 30-Hz treatment paradigm resulted in significantly larger neurospheres only after 2 weeks. Importantly, rTMS treatment at both frequencies increased neuronal differentiation of the harvested NS/PCs. Furthermore, one week in vitro rTMS treatment of NS/PCs with both 1-Hz and 30-Hz increased NS/PCs proliferation and neuronal differentiation. It is concluded that both 1-Hz and 30-Hz rTMS treatment increase NS/PCs proliferation and neuronal differentiation. PMID:26140221

  13. Movement-generated afference paired with transcranial magnetic stimulation: an associative stimulation paradigm

    PubMed Central

    2014-01-01

    Background A peripheral nerve stimulus can enhance or suppress the evoked response to transcranial magnetic stimulation (TMS) depending on the latency of the preceding peripheral nerve stimulation (PNS) pulse. Similarly, somatosensory afference from the passively moving limb can transiently alter corticomotor excitability, in a phase-dependent manner. The repeated association of PNS with TMS is known to modulate corticomotor excitability; however, it is unknown whether repeated passive-movement associative stimulation (MAS) has similar effects. Methods In a proof-of-principle study, using a cross-over design, seven healthy subjects received in separate sessions: (1) TMS (120% of the resting motor threshold-RMT, optimal site for Flexor Carpi Radialis) with muscle at rest; (2) TMS paired with cyclic passive movement during extension cyclic passive movement (400 pairs, 1 Hz), with the intervention order randomly assigned. Normality was tested using the Kolmogorov-Smirnov test, then compared to pre-intervention baseline using repeated measures ANOVA with a Dunnet multiple comparisons test. Results MAS led to a progressive and significant decrease in the motor evoked potential (MEP) amplitude over the intervention (R2?=?0.6665, P?

  14. Stability of the multi-finger prehension synergy studied with transcranial magnetic stimulation

    PubMed Central

    Niu, Xun; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2008-01-01

    We used transcranial magnetic stimulation (TMS) to explore the stability of the three constituents of the multi-finger prehension synergy. Patterns of co-variation between mechanical variables produced by individual digits were used as indices of the prehension synergy. We tested hypotheses that TMS would violate these patterns and that different components of the prehension synergy would take different times to restore. Subjects held an instrumented handle with one of the three external load and one of the seven external torques statically in the air. Single-pulse TMS was applied unexpectedly over the hand projection in the contralateral hemisphere. The normal forces showed a quick TMS-induced increase that was proportional to the background force magnitude. This was also true for the tangential forces produced by the thumb, middle and ring fingers but not by the index and little fingers. The total moment of force changed proportionally to its background value with predominance of supination responses. During the quick force response to TMS, patterns of digit force co-variation stabilizing the total tangential force and total moment of force were violated. Two stages of synergy restoration were identified taking approximately 0.3 s and 1.5 s. These times differed among the three synergy components. The results support the idea of a prehension synergy as a neural mechanism that facilitates conjoint changes in forces produced by individual digits with the purpose to stabilize the hand action on the hand-held object. The data also support applicability of the principle of superposition to the human hand action. PMID:18592229

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

    PubMed Central

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

    2010-01-01

    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

  16. The effect of repetitive transcranial magnetic stimulation on monoamine outflow in the nucleus accumbens shell in freely moving rats.

    PubMed

    Löffler, Susanne; Gasca, Fernando; Richter, Lars; Leipscher, Ulrike; Trillenberg, Peter; Moser, Andreas

    2012-10-01

    Evidence exists that modulation of neuronal activity in nucleus accumbens shell region may re-establish normal function in various neuropsychiatric conditions such as drug-withdrawal, obsessive-compulsive disorder, depression and chronic pain. Here, we study the effects of acute repetitive transcranial magnetic stimulation on monoamine outflow in the nucleus accumbens shell in awake and freely moving rats using in vivo microdialysis. To scale the biochemical results to the induced electric field in the rat brain, we obtained a realistic simulation of the stimulation scenario using a finite element model. Applying 20 Hz repetitive transcranial magnetic stimulation in 6 trains of 50 stimuli with 280 ?s pulse width at a magnetic field strength of 130% of the individual motor threshold, dopamine as well as serotonin outflow in the nucleus accumbens shell significantly increased compared to sham stimulation. Since the electric field decays rapidly with depth in the rat brain, we can conclude that the modulation in neurotransmitter outflow from the nucleus accumbens shell is presumably a remote effect of cortical stimulation. PMID:22771976

  17. The effect of head and coil modeling for the calculation of induced electric field during transcranial magnetic stimulation.

    PubMed

    Tachas, Nikolaos J; Samaras, Theodoros

    2014-07-01

    In the present work we studied some of the features related to transcranial magnetic stimulation (TMS) computational modeling. Particularly we investigated the impact of head model resolution on the estimated distribution of the induced electric field, as well as the role of the stimulating magnetic coil model in TMS. Using the impedance method we calculated the induced electric field inside a realistic numerical phantom of the human head from a commercially available eight-shaped coil, which was modeled in two ways. The results showed that finer resolution of the model has better performance at tissue interfaces eliminating numerical artifacts of local peaks. Furthermore, the geometrical details of a TMS coil must be taken into account since the predicted amount of volume of brain tissue involved can have great variation. Finally, the secondary magnetic field that is generated by the induced eddy currents in the tissues can be neglected. PMID:23872490

  18. Developments in deep brain stimulation using time dependent magnetic fields

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  19. Developments in deep brain stimulation using time dependent magnetic fields

    SciTech Connect

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

    2012-03-07

    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.

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

    PubMed

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

    2014-11-01

    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

  1. Preliminary Evidence of the Effects of High-frequency Repetitive Transcranial Magnetic Stimulation (rTMS) on Swallowing Functions in Post-Stroke Individuals with Chronic Dysphagia

    ERIC Educational Resources Information Center

    Cheng, Ivy K. Y.; Chan, Karen M. K.; Wong, C. S.; Cheung, Raymond T. F.

    2015-01-01

    Background: There is growing evidence of potential benefits of repetitive transcranial magnetic stimulation (rTMS) in the rehabilitation of dysphagia. However, the site and frequency of stimulation for optimal effects are not clear. Aims: The aim of this pilot study is to investigate the short-term effects of high-frequency 5 Hz rTMS applied to…

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

    Microsoft Academic Search

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

    1996-01-01

    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

  3. Low-Frequency Repetitive Transcranial Magnetic Stimulation and Intensive Occupational Therapy for Poststroke Patients with Upper Limb Hemiparesis: Preliminary Study of a 15-Day Protocol

    ERIC Educational Resources Information Center

    Kakuda, Wataru; Abo, Masahiro; Kobayashi, Kazushige; Momosaki, Ryo; Yokoi, Aki; Fukuda, Akiko; Ishikawa, Atsushi; Ito, Hiroshi; Tominaga, Ayumi

    2010-01-01

    The purpose of the study was to determine the safety and feasibility of a 15-day protocol of low-frequency repetitive transcranial magnetic stimulation (rTMS) combined with intensive occupational therapy (OT) on motor function and spasticity in hemiparetic upper limbs in poststroke patients. Fifteen poststroke patients (age at study entry 55 [plus…

  4. Selection of Action: Can transcranial magnetic stimulation influence hand choice in reaching? 1 Helen Wills Neuroscience Institute,Department of Psychology,University of California,Berkeley

    E-print Network

    Oliva, Aude

    Selection of Action: Can transcranial magnetic stimulation influence hand choice in reaching? 1,Natalie Marchant,Timothy Verstynen,Joern Diedrichson,and Richard Ivry. 1 1 1 12 Hand Choice Curve: Subjects used for central reaches affect reaction time?When reaching for something in front of you,which hand do you use

  5. Effects of Repetitive Transcranial Magnetic Stimulation on Motor Symptoms in Parkinson Disease

    PubMed Central

    Chou, Ying-hui; Hickey, Patrick T.; Sundman, Mark; Song, Allen W.; Chen, Nan-kuei

    2015-01-01

    IMPORTANCE Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive neuromodulation technique that has been closely examined as a possible treatment for Parkinson disease (PD). However, results evaluating the effectiveness of rTMS in PD are mixed, mostly owing to low statistical power or variety in individual rTMS protocols. OBJECTIVES To determine the rTMS effects on motor dysfunction in patients with PD and to examine potential factors that modulate the rTMS effects. DATA SOURCES Databases searched included PubMed, EMBASE, Web of Knowledge, Scopus, and the Cochrane Library from inception to June 30, 2014. STUDY SELECTION Eligible studies included sham-controlled, randomized clinical trials of rTMS intervention for motor dysfunction in patients with PD. DATA EXTRACTION AND SYNTHESIS Relevant measures were extracted independently by 2 investigators. Standardized mean differences (SMDs) were calculated with random-effects models. MAIN OUTCOMES AND MEASURES Motor examination of the Unified Parkinson’s Disease Rating Scale. RESULTS Twenty studies with a total of 470 patients were included. Random-effects analysis revealed a pooled SMD of 0.46 (95%CI, 0.29–0.64), indicating an overall medium effect size favoring active rTMS over sham rTMS in the reduction of motor symptoms (P < .001). Subgroup analysis showed that the effect sizes estimated from high-frequency rTMS targeting the primary motor cortex (SMD, 0.77; 95%CI, 0.46–1.08; P < .001) and low-frequency rTMS applied over other frontal regions (SMD, 0.50; 95%CI, 0.13–0.87; P = .008) were significant. The effect sizes obtained from the other 2 combinations of rTMS frequency and rTMS site (ie, high-frequency rTMS at other frontal regions: SMD, 0.23; 95% CI, ?0.02 to 0.48, and low primary motor cortex: SMD, 0.28; 95%CI, ?0.23 to 0.78) were not significant. Meta-regression revealed that a greater number of pulses per session or across sessions is associated with larger rTMS effects. Using the Grading of Recommendations, Assessment, Development, and Evaluation criteria, we characterized the quality of evidence presented in this meta-analysis as moderate quality. CONCLUSIONS AND RELEVANCE The pooled evidence suggests that rTMS improves motor symptoms for patients with PD. Combinations of rTMS site and frequency as well as the number of rTMS pulses are key modulators of rTMS effects. The findings of our meta-analysis may guide treatment decisions and inform future research. PMID:25686212

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

    PubMed Central

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

    2005-01-01

    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

  7. Repetitive Transcranial Magnetic Stimulation for the Treatment of Major Depressive Disorder

    PubMed Central

    2004-01-01

    Executive Summary Objective This review was conducted to assess the effectiveness of repetitive transcranial magnetic stimulation (rTMS) in the treatment of major depressive disorder (MDD). The Technology rTMS is a noninvasive way to stimulate nerve cells in areas of the brain. During rTMS, an electrical current passes through a wire coil placed over the scalp. The current induces a magnetic field that produces an electrical field in the brain that then causes nerve cells to depolarize, resulting in the stimulation or disruption of brain activity. Researchers have investigated rTMS as an option to treat MDD, as an add-on to drug therapy, and, in particular, as an alternative to electroconvulsive therapy (ECT) for patients with treatment-resistant depression. The advantages of rTMS over ECT for patients with severe refractory depression are that general anesthesia is not needed, it is an outpatient procedure, it requires less energy, the simulation is specific and targeted, and convulsion is not required. The advantages of rTMS as an add-on treatment to drug therapy may include hastening of the clinical response when used with antidepressant drugs. Review Strategy The Medical Advisory Secretariat used its standard search strategy to locate international health technology assessments and English-language journal articles published from January 1996 to March 2004. Summary of Findings Some early meta-analyses suggested rTMS might be effective for the treatment of MDD (for treatment-resistant MDD and as an add-on treatment to drug therapy for patients not specifically defined as treatment resistant). There were, however, several crucial methodological limitations in the included studies that were not critically assessed. These are discussed below. Recent meta-analyses (including 2 international health technology assessments) have done evidence-based critical analyses of studies that have assessed rTMS for MDD. The 2 most recent health technology assessments (from the Oxford Cochrane Collaboration and the Norwegian Centre for Health Technology Assessment) concluded that there is no evidence that rTMS is effective for the treatment of MDD, either as compared with a placebo for patients with treatment-resistant or nontreatment-resistant MDD, or as an alternative to ECT for patients with treatment-resistant MDD. This mainly due to the poor quality of the studies. The major methodological limitations were identified in older meta-analyses, recent health technology assessments, and the most recently published trials (Level 2–4 evidence) on the effectiveness of rTMS for MDD are discussed below. Small sample size was a limitation acknowledged by many of the authors. There was also a lack of a priori sample size calculation or justification. Biased randomization may have been a problem. Generally, the published reports lacked detailed information on the method of allocation concealment used. This is important because it is impossible to determine if there was a possible influence (direct or indirect) in the allocation of the patients to different treatment groups. The trials were single blind, evaluated by external blinded assessors, rather than double blind. Double blinding is more robust, because neither the participants nor the investigators know which participants are receiving the active treatment and which are getting a placebo. Those administering rTMS, however, cannot be blinded to whether they are administering the active treatment or a placebo. There was patient variability among the studies. In some studies, the authors said that patients were “medication resistant,” but the definitions of resistant, if provided, were inconsistent or unclear. For example, some described “medication resistant” as failing at least one trial of drugs during the current depressive episode. Furthermore, it was unclear if the term “medication resistant” referred to antidepressants only or to combinations of antidepressants and other drug augmentation strategies (such as neuroleptics, benzodiazepine

  8. Neuroendocrine and Behavioral Effects of Repetitive Transcranial Magnetic Stimulation in a Psychopathological Animal Model Are Suggestive of Antidepressant-like Effects

    Microsoft Academic Search

    Martin E. Keck; Tobias Welt; Anke Post; Marianne B. Müller; Nicola Toschi; Alexandra Wigger; Rainer Landgraf; Florian Holsboer; Mario Engelmann

    2001-01-01

    The neuroendocrine and behavioral effects of repetitive transcranial magnetic stimulation (rTMS) were investigated in two rat lines selectively bred for high and low anxiety-related behavior. The stimulation parameters were adjusted according to the results of accurate computer-assisted and magnetic resonance imaging-based reconstructions of the current density distributions induced by rTMS in the rat and human brain, ensuring comparable stimulation patterns

  9. The potential of transcranial magnetic stimulation for population-based application: a region-based illustrated brief overview.

    PubMed

    Mahayana, Indra T; Sari, Dwi C R; Chen, Chiao-Yun; Juan, Chi-Hung; Muggleton, Neil G

    2014-10-01

    The awareness of the global trends in neuroscience study, especially in the cognitive neuroscience field, should be increased. One notable approach is the use of transcranial magnetic stimulation (TMS) not only as a research tool but also as a choice for treatment and rehabilitation in neurological disorders, such as post-stroke hemiplegia, visuospatial neglect syndrome, Alzheimer's disease (AD) and psychiatric conditions such as major depression and schizophrenia. All of these occur in significant numbers in highly populated regions. This paper briefly discusses the basic protocols and potential benefits of using TMS with the aim of providing insight that is useful in the design of future public health strategies in highly populated regions with a large neurocognitive burden of disease where this technique is currently underemployed. PMID:24392811

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed Central

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

    2012-01-01

    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

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed Central

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

    2015-01-01

    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

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

    PubMed Central

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

    2015-01-01

    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. PMID:25762919

  15. Characterisation of paired-pulse transcranial magnetic stimulation conditions yielding intracortical inhibition or I-wave facilitation using a threshold-hunting paradigm

    Microsoft Academic Search

    Friedemann Awiszus; Helmut Feistner; Dietmar Urbach; Hugh Bostock

    1999-01-01

    Short-interval, paired-pulse transcranial magnetic stimulation (TMS) is usually used to demonstrate intracortical inhibition.\\u000a It was shown recently that with short-interval, paired-pulse TMS a facilitation – called intracortical I-wave facilitation\\u000a – can also be demonstrated. It was the aim of this study to investigate which stimulus conditions lead to intracortical inhibition\\u000a and what conditions yield an intracortical I-wave facilitation in a

  16. Effects of single-pulse transcranial magnetic stimulation (TMS) on functional brain activity: a combined event-related TMS and evoked potential study

    Microsoft Academic Search

    G. Thut; G. Northoff; J. R. Ives; Y. Kamitani; A. Pfennig; F. Kampmann; D. L. Schomer; A. Pascual-Leone

    2003-01-01

    Objective: To further evaluate the potential of slew-rate limiting amplifiers to record electrophysiological signals in spite of concurrent transcranial magnetic stimulation (TMS), and to explore the effects of single-pulse TMS on electroencephalographic (EEG) correlates of functional brain activity.Methods: Visual-evoked potentials (VEPs) to checkerboards were recorded in 7 right-handed subjects, while single-pulse TMS was applied to the occipital pole either at

  17. Repetitive transcranial magnetic stimulation is as effective as electroconvulsive therapy in the treatment of nondelusional major depressive disorder: an open study

    Microsoft Academic Search

    Leon Grunhaus; Pinhas N. Dannon; Shaul Schreiber; Ornah H. Dolberg; Revital Amiaz; Reuven Ziv; Eli Lefkifker

    2000-01-01

    %Background: Repetitive transcranial magnetic stimulation (rTMS), a new method for the stimulation of the central nervous system, is being proposed as a potential new treatment in patients with major depressive disorder (MDD). We tested the hypothesis that rTMS would be as effective as electroconvulsive therapy (ECT) in patients with MDD.Methods: Forty patients with MDD referred for ECT were randomly assigned

  18. Improvement of motor performance and modulation of cortical excitability by repetitive transcranial magnetic stimulation of the motor cortex in Parkinson's disease

    Microsoft Academic Search

    Jean-Pascal Lefaucheur; Xavier Drouot; Florian Von Raison; Isabelle Ménard-Lefaucheur; Pierre Cesaro; Jean-Paul Nguyen

    2004-01-01

    Objective: To assess the effects of focal motor cortex stimulation on motor performance and cortical excitability in patients with Parkinson's disease (PD).Methods: Repetitive transcranial magnetic stimulation (rTMS) was performed on the left motor cortical area corresponding to the right hand in 12 ‘off-drug’ patients with PD. The effects of subthreshold rTMS applied at 0.5 Hz (600 pulses) or at 10

  19. Remediation of Sleep-Deprivation–Induced Working Memory Impairment with fMRI-Guided Transcranial Magnetic Stimulation

    PubMed Central

    Stanford, A. D.; Bulow, P.; Nguyen, T.; Rakitin, B. C.; Habeck, C.; Basner, R.; Stern, Y.; Lisanby, S. H.

    2008-01-01

    Repetitive transcranial magnetic stimulation (rTMS) was applied to test the role of selected cortical regions in remediating sleep-deprivation–induced deficits in visual working memory (WM) performance. Three rTMS targets were chosen using a functional magnetic resonance imaging (fMRI)–identified network associated with sleep-deprivation–induced WM performance impairment: 2 regions from the network (upper left middle occipital gyrus and midline parietal cortex) and 1 nonnetwork region (lower left middle occipital gyrus). Fifteen participants underwent total sleep deprivation for 48 h. rTMS was applied at 5 Hz during a WM task in a within-subject sham-controlled design. The rTMS to the upper-middle occipital site resulted in a reduction of the sleep-induced reaction time deficit without a corresponding decrease in accuracy, whereas stimulation at the other sites did not. Each subject had undergone fMRI scanning while performing the task both pre- and postsleep deprivation, and the degree to which each individual activated the fMRI network was measured. The degree of performance enhancement with upper-middle occipital rTMS correlated with the degree to which each individual failed to sustain network activation. No effects were found in a subset of participants who performed the same rTMS procedure after recovering from sleep deprivation, suggesting that the performance enhancements seen following sleep deprivation were state dependent. PMID:18203694

  20. An efficient 3-D eddy-current solver using an independent impedance method for transcranial magnetic stimulation.

    PubMed

    De Geeter, Nele; Crevecoeur, Guillaume; Dupre, Luc

    2011-02-01

    In many important bioelectromagnetic problem settings, eddy-current simulations are required. Examples are the reduction of eddy-current artifacts in magnetic resonance imaging and techniques, whereby the eddy currents interact with the biological system, like the alteration of the neurophysiology due to transcranial magnetic stimulation (TMS). TMS has become an important tool for the diagnosis and treatment of neurological diseases and psychiatric disorders. A widely applied method for simulating the eddy currents is the impedance method (IM). However, this method has to contend with an ill conditioned problem and consequently a long convergence time. When dealing with optimal design problems and sensitivity control, the convergence rate becomes even more crucial since the eddy-current solver needs to be evaluated in an iterative loop. Therefore, we introduce an independent IM (IIM), which improves the conditionality and speeds up the numerical convergence. This paper shows how IIM is based on IM and what are the advantages. Moreover, the method is applied to the efficient simulation of TMS. The proposed IIM achieves superior convergence properties with high time efficiency, compared to the traditional IM and is therefore a useful tool for accurate and fast TMS simulations. PMID:20959261

  1. Comparison of two protocols of transcranial magnetic stimulation for treatment of chronic tinnitus: a randomized controlled clinical trial of burst repetitive versus high-frequency repetitive Transcranial Magnetic Stimulation.

    PubMed

    Forogh, Bijan; Yazdi-Bahri, Seyedeh-Maryam; Ahadi, Tannaz; Fereshtehnejad, Seyed-Mohammad; Raissi, Gholam Reza

    2014-02-01

    The aim of the study was to compare the effects of two techniques of repetitive Transcranial Magnetic Stimulation (rTMS) to treat chronic tinnitus; continuous Theta Burst Stimulation (cTBS) and high-frequency rTMS. In a controlled randomized clinical trial, 55 patients with chronic tinnitus were randomly divided in two groups. They received four sessions of treatment. cTBS was tested on one group and high-frequency rTMS (10 Hz) was tested on the other. Severity of the tinnitus was assessed before treatment, after the last treatment session and then 1-month later. Both the treatments of high-frequency and cTBS had a suppressive effect on tinnitus. However, cTBS was more effective than high-frequency rTMS (P = 0.001). This study suggests that rTMS even in four sessions is effective in reducing tinnitus severity; moreover, compared to high-frequency TMS better results can be achieved with cTBS. PMID:23852313

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

    PubMed

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

    2014-01-01

    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

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

    PubMed

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

    2015-04-15

    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

  4. The effect of computer-assisted cognitive rehabilitation and repetitive transcranial magnetic stimulation on cognitive function for stroke patients

    PubMed Central

    Park, In-Seok; Yoon, Jung-Gyu

    2015-01-01

    [Purpose] This study investigated the effects of computer-assisted cognitive rehabilitation (CACR) and repetitive transcranial magnetic stimulation (rTMS) on cognitive function in patients with stroke. [Subjects and Methods] We enrolled 20 patients and divided them into CACR and rTMS groups. CACR and rTMS were performed thrice a week for 4 weeks. Cognitive function was measured with the Korean Mini-Mental State Examination (K-MMSE) and Lowenstein Occupational Therapy Cognitive Assessment-Geriatric (LOTCA-G) before and after treatment. The independent samples t-test was performed to test the homogeneity of K-MMSE and LOTCA-G before treatment and compare the differences in cognitive improvement between the CACR and rTMS groups. A paired samples t-test was used to compare cognitive function before and after treatment. [Results] Cognitive function of both the groups significantly improved after the intervention based on the K-MMSE and LOTCA-G scores. While the LOTCA-G score improved significantly more in the CACR group than in the rTMS group, no significant difference was seen in the K-MMSE scores. [Conclusion] We showed that CACR is more effective than rTMS in improving cognitive function after stroke. PMID:25931728

  5. Using repetitive transcranial magnetic stimulation to study the underlying neural mechanisms of human motor learning and memory

    PubMed Central

    Censor, Nitzan; Cohen, Leonardo G

    2011-01-01

    In the last two decades, there has been a rapid development in the research of the physiological brain mechanisms underlying human motor learning and memory. While conventional memory research performed on animal models uses intracellular recordings, microfusion of protein inhibitors to specific brain areas and direct induction of focal brain lesions, human research has so far utilized predominantly behavioural approaches and indirect measurements of neural activity. Repetitive transcranial magnetic stimulation (rTMS), a safe non-invasive brain stimulation technique, enables the study of the functional role of specific cortical areas by evaluating the behavioural consequences of selective modulation of activity (excitation or inhibition) on memory generation and consolidation, contributing to the understanding of the neural substrates of motor learning. Depending on the parameters of stimulation, rTMS can also facilitate learning processes, presumably through purposeful modulation of excitability in specific brain regions. rTMS has also been used to gain valuable knowledge regarding the timeline of motor memory formation, from initial encoding to stabilization and long-term retention. In this review, we summarize insights gained using rTMS on the physiological and neural mechanisms of human motor learning and memory. We conclude by suggesting possible future research directions, some with direct clinical implications. PMID:21041531

  6. Using repetitive transcranial magnetic stimulation to study the underlying neural mechanisms of human motor learning and memory.

    PubMed

    Censor, Nitzan; Cohen, Leonardo G

    2011-01-01

    In the last two decades, there has been a rapid development in the research of the physiological brain mechanisms underlying human motor learning and memory. While conventional memory research performed on animal models uses intracellular recordings, microfusion of protein inhibitors to specific brain areas and direct induction of focal brain lesions, human research has so far utilized predominantly behavioural approaches and indirect measurements of neural activity. Repetitive transcranial magnetic stimulation (rTMS), a safe non-invasive brain stimulation technique, enables the study of the functional role of specific cortical areas by evaluating the behavioural consequences of selective modulation of activity (excitation or inhibition) on memory generation and consolidation, contributing to the understanding of the neural substrates of motor learning. Depending on the parameters of stimulation, rTMS can also facilitate learning processes, presumably through purposeful modulation of excitability in specific brain regions. rTMS has also been used to gain valuable knowledge regarding the timeline of motor memory formation, from initial encoding to stabilization and long-term retention. In this review, we summarize insights gained using rTMS on the physiological and neural mechanisms of human motor learning and memory. We conclude by suggesting possible future research directions, some with direct clinical implications. PMID:21041531

  7. Bilateral Repetitive Transcranial Magnetic Stimulation Combined with Intensive Swallowing Rehabilitation for Chronic Stroke Dysphagia: A Case Series Study

    PubMed Central

    Momosaki, Ryo; Abo, Masahiro; Kakuda, Wataru

    2014-01-01

    The purpose of this study was to clarify the safety and feasibility of a 6-day protocol of bilateral repetitive transcranial magnetic stimulation (rTMS) combined with intensive swallowing rehabilitation for chronic poststroke dysphagia. In-hospital treatment was provided to 4 poststroke patients (age at treatment: 56–80 years; interval between onset of stroke and treatment: 24–37 months) with dysphagia. Over 6 consecutive days, each patient received 10 sessions of rTMS at 3 Hz applied to the pharyngeal motor cortex bilaterally, followed by 20 min of intensive swallowing rehabilitation exercise. The swallowing function was evaluated by the Penetration Aspiration Scale (PAS), Modified Mann Assessment of Swallowing Ability (MMASA), Functional Oral Intake Scale (FOIS), laryngeal elevation delay time (LEDT) and Repetitive Saliva-Swallowing Test (RSST) on admission and at discharge. All patients completed the 6-day treatment protocol and none showed any adverse reactions throughout the treatment. The combination treatment improved laryngeal elevation delay time in all patients. Our proposed protocol of rTMS plus swallowing rehabilitation exercise seems to be safe and feasible for chronic stroke dysphagia, although its efficacy needs to be confirmed in a large number of patients. PMID:24803904

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

    PubMed Central

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

    2012-01-01

    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

  9. The role of the right presupplementary motor area in stopping action: two studies with event-related transcranial magnetic stimulation.

    PubMed

    Cai, Weidong; George, Jobi S; Verbruggen, Frederick; Chambers, Christopher D; Aron, Adam R

    2012-07-01

    Rapidly stopping action engages a network in the brain including the right presupplementary motor area (preSMA), the right inferior frontal gyrus, and the basal ganglia. Yet the functional role of these different regions within the overall network still remains unclear. Here we focused on the role of the right preSMA in behavioral stopping. We hypothesized that the underlying neurocognitive function of this region is one or more of setting up a stopping rule in advance, modulating response tendencies (e.g., slowing down in anticipation of stopping), and implementing stopping when the stop signal occurs. We performed two experiments with magnetic resonance imaging (MRI)-guided, event-related, transcranial magnetic stimulation(TMS), during the performance of variants of the stop signal task. In experiment 1 we show that stimulation of the right preSMA versus vertex (control site) slowed the implementation of stopping (measured via stop signal reaction time) but had no influence on modulation of response tendencies. In experiment 2, we showed that stimulation of the right preSMA slowed implementation of stopping in a mechanistically selective form of stopping but had no influence on setting up stopping rules. The results go beyond the replication of prior findings by showing that TMS of the right preSMA impairs stopping behavior (including a behaviorally selective form of stopping) through a specific disruption of the implementation of stopping. Future studies are required to establish whether this was due to stimulation of the right preSMA itself or because of remote effects on the wider stopping network. PMID:22514296

  10. Effect of Epidural Electrical Stimulation and Repetitive Transcranial Magnetic Stimulation in Rats With Diffuse Traumatic Brain Injury

    PubMed Central

    Yoon, Yong-Soon; Cho, Kang Hee; Kim, Eun-Sil; Lee, Mi-Sook

    2015-01-01

    Objective To evaluate the effects of epidural electrical stimulation (EES) and repetitive transcranial magnetic stimulation (rTMS) on motor recovery and brain activity in a rat model of diffuse traumatic brain injury (TBI) compared to the control group. Methods Thirty rats weighing 270-285 g with diffuse TBI with 45 kg/cm2 using a weight-drop model were assigned to one of three groups: the EES group (ES) (anodal electrical stimulation at 50 Hz), the rTMS group (MS) (magnetic stimulation at 10 Hz, 3-second stimulation with 6-second intervals, 4,000 total stimulations per day), and the sham-treated control group (sham) (no stimulation). They were pre-trained to perform a single-pellet reaching task (SPRT) and a rotarod test (RRT) for 14 days. Diffuse TBI was then induced and an electrode was implanted over the dominant motor cortex. The changes in SPRT success rate, RRT performance time rate and the expression of c-Fos after two weeks of EES or rTMS were tracked. Results SPRT improved significantly from day 8 to day 12 in the ES group and from day 4 to day 14 in the MS group (p<0.05) compared to the sham group. RRT improved significantly from day 6 to day 11 in ES and from day 4 to day 9 in MS compared to the sham group. The ES and MS groups showed increased expression of c-Fos in the cerebral cortex compared to the sham group. Conclusion ES or MS in a rat model of diffuse TBI can be used to enhance motor recovery and brain activity. PMID:26161348

  11. Increases in frontostriatal connectivity are associated with response to dorsomedial repetitive transcranial magnetic stimulation in refractory binge/purge behaviors

    PubMed Central

    Dunlop, Katharine; Woodside, Blake; Lam, Eileen; Olmsted, Marion; Colton, Patricia; Giacobbe, Peter; Downar, Jonathan

    2015-01-01

    Background Conventional treatments for eating disorders are associated with poor response rates and frequent relapse. Novel treatments are needed, in combination with markers to characterize and predict treatment response. Here, resting-state functional magnetic resonance imaging (rs-fMRI) was used to identify predictors and correlates of response to repetitive transcranial magnetic stimulation (rTMS) of the dorsomedial prefrontal cortex (dmPFC) at 10 Hz for eating disorders with refractory binge/purge symptomatology. Methods 28 subjects with anorexia nervosa, binge?purge subtype or bulimia nervosa underwent 20–30 sessions of 10 Hz dmPFC rTMS. rs-fMRI data were collected before and after rTMS. Subjects were stratified into responder and nonresponder groups using a criterion of ?50% reduction in weekly binge/purge frequency. Neural predictors and correlates of response were identified using seed-based functional connectivity (FC), using the dmPFC and adjacent dorsal anterior cingulate cortex (dACC) as regions of interest. Results 16 of 28 subjects met response criteria. Treatment responders had lower baseline FC from dmPFC to lateral orbitofrontal cortex and right posterior insula, and from dACC to right posterior insula and hippocampus. Responders had low baseline FC from the dACC to the ventral striatum and anterior insula; this connectivity increased over treatment. However, in nonresponders, frontostriatal FC was high at baseline, and dmPFC-rTMS suppressed FC in association with symptomatic worsening. Conclusions Enhanced frontostriatal connectivity was associated with responders to dmPFC-rTMS for binge/purge behavior. rTMS caused paradoxical suppression of frontostriatal connectivity in nonresponders. rs-fMRI could prove critical for optimizing stimulation parameters in a future sham-controlled trial of rTMS in disordered eating. PMID:26199873

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

    PubMed Central

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

    2011-01-01

    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

  13. [Transcranial magnetic electro-stimulation with alternate action on brain hemispheres in the correction of cerebral disturbances in children with diabetes mellitus type 1].

    PubMed

    Filina, N Iu; Bolotova, N V; Ra?gorodski?, Iu M; Nikolaeva, N V

    2012-01-01

    Correction of psychoemotional and autonomic disturbances in children 7-17 years old with diabetes mellitus type 1 was conducted using transcranial magnetic electro-stimulation with alternate action on brain hemispheres (main group, 42 patients). The method includes the combined action of magnetic field pulses and series of electric impulses; magnetic and electric stimulation were performed synchronously - at first, on one brain hemisphere, then on another hemisphere with alternation frequency 9.5-10.5 Hz. A comparison group consisted of 44 patients with diabetes mellitus type 1 who received physiotherapeutic treatment as a combination of transcranial magnetic therapy and electro-stimulation with simultaneous action on both brain hemispheres. Treatment duration was 10 sessions. Treatment efficacy was assessed by the decrease in frequency and intensity of complaints, improvement of patient's health status measured (a scale for assessment of activity, health perception and mood) and improvement of the status of the autonomic nervous system (Vein's questionnaire), mental sphere (the Luscher color test) and cognitive traits (The Concentrated Attention Test of the Toulouse-Pierron Factorial Battery). The status of the autonomic nervous system was evaluated before and after the treatment using cardiointervalography. Brain bioelectrical activity was assessed using encephalography. Significant reduction of autonomic, psychoemotional and cognitive disturbances, normalization of brain bioelectrical activity due to the ?-rhythm organization and arrhythmia removal were identified in the main group after the treatment. No adverse effects of this physiotherapeutic treatment was found. PMID:22677753

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

    PubMed Central

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

    2014-01-01

    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

  15. Cognitive and Anatomical Underpinnings of the Conceptual Knowledge for Common Objects and Familiar People: A Repetitive Transcranial Magnetic Stimulation Study

    PubMed Central

    Campanella, Fabio; Fabbro, Franco; Urgesi, Cosimo

    2013-01-01

    Several studies have addressed the issue of how knowledge of common objects is organized in the brain, whereas the cognitive and anatomical underpinnings of familiar people knowledge have been less explored. Here we applied repetitive transcranial magnetic stimulation (rTMS) over the left and right temporal poles before asking healthy individuals to perform a speeded word-to-picture matching task using familiar people and common objects as stimuli. We manipulated two widely used semantic variables, namely the semantic distance and the familiarity of stimuli, to assess whether the semantic organization of familiar people knowledge is similar to that of common objects. For both objects and faces we reliably found semantic distance and familiarity effects, with less accurate and slower responses for stimulus pairs that were more closely related and less familiar. However, the effects of semantic variables differed across categories, with semantic distance effects larger for objects and familiarity effects larger for faces, suggesting that objects and faces might share a partially comparable organization of their semantic representations. The application of rTMS to the left temporal pole modulated, for both categories, semantic distance, but not familiarity effects, revealing that accessing object and face concepts might rely on overlapping processes within left anterior temporal regions. Crucially, rTMS of the left temporal pole affected only the recognition of pairs of stimuli that could be discriminated at specific levels of categorization (e.g., two kitchen tools or two famous persons), with no effect for discriminations at either superordinate or individual levels. Conversely, rTMS of the right temporal pole induced an overall slowing of reaction times that positively correlated with the visual similarity of the stimuli, suggesting a more perceptual rather than semantic role of the right anterior temporal regions. Results are discussed in the light of current models of face and object semantic representations in the brain. PMID:23704999

  16. Comparison of the outcomes of repetitive transcranial magnetic stimulation to the ipsilateral and contralateral auditory cortex in unilateral tinnitus.

    PubMed

    Kim, Bo Gyung; Kim, Deog Young; Kim, Seung Ki; Kim, Jung Min; Baek, Seung Hak; Moon, In Seok

    2014-09-01

    Transcranial magnetic stimulation (TMS) is a noninvasive method of activating or deactivating focal areas of the human brain. Repetitive TMS (rTMS) applied over the temporoparietal cortex has been reported to show therapeutic effects on tinnitus. We compared the effects of 1?Hz rTMS delivered either contralaterally or ipsilaterally to the symptomatic ear in patients with unilateral tinnitus. Forty patients with asymmetric hearing loss and non-pulsatile tinnitus localized to poorer ear of 6 months in duration or greater who were refractory to medication were enrolled in this study. Patients were assigned randomly to one of two treatment groups: with 1?Hz stimulation applied the temporoparietal junction either ipsilaterally (n?=?21) or contralaterally (n?=?19) to the symptomatic ear. The patients were given 600 pulses per session daily for 5?d. Changes in the tinnitus handicap inventory (THI) and self-rating visual analog scores (VAS) for loudness, awareness and annoyance were analyzed before, immediately after and 1 month after treatment. There was no significant difference in the rate of patients with marked improvement between ipsilateral and contralateral stimulation groups. In addition, there were no significant differences in the amount of decreases in THI scores and VAS between the two groups immediately or 1 month after rTMS. Finally, significant decreases in THI scores and most VAS were observed 1 month after rTMS in both groups compared to pretreatment. Daily treatment with 1?Hz rTMS ipsilaterally and contralaterally to the side of tinnitus both had significant beneficial effects. The laterality of stimulation with 1?Hz rTMS is not the decisive factor in relieving symptoms. PMID:23781982

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

    PubMed Central

    2014-01-01

    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

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

    PubMed Central

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

    2014-01-01

    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

  19. The effects of transcranial magnetic stimulation on vibratory-induced presynaptic inhibition of the soleus H reflex.

    PubMed

    Guzmán-López, Jessica; Costa, João; Selvi, Aikaterini; Barraza, Gonzalo; Casanova-Molla, Jordi; Valls-Solé, Josep

    2012-08-01

    A single-pulse transcranial magnetic stimulus (TMS) may induce contraction in many muscles of the body at the same time. This is specially the case when using the double-cone coil to obtain the motor evoked potentials in leg muscles. Even if intensity is kept below threshold for the soleus muscle, TMS induces facilitation of the soleus H reflex that is separated into two phases: the first, peaking at 10-20 ms and the second, peaking at 70-90 ms. We investigated the possibility that TMS-induced facilitation of the H reflex was related, at least in part, to the reafferentation volley reaching the alpha motoneuron after synchronized contraction of other muscles in the body. To test this hypothesis, we examined the effects of vibration on the TMS-induced facilitation of the soleus H reflex. As expected, vibration applied over the triceps tendon caused a significant reduction in H reflex amplitude: 42.4 ± 6.4 % of control values. When conditioned by TMS at intervals corresponding to the first phase, the H reflex was facilitated to the same extent in both conditions: with and without vibration. However, at intervals corresponding to the second facilitation phase, there was a significantly reduced facilitation with vibration. These differential effects of vibration on the two phases of the TMS-induced facilitation of the H reflex indicate a different mechanism for each facilitation phase. The first phase could result from direct corticospinal excitatory input, while the second phase might depend on inputs via Ia afferents from heteronymous muscles. PMID:22644238

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

    PubMed

    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

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  2. FPGA-Based Acceleration of the Computations Involved in Transcranial Magnetic Stimulation

    Microsoft Academic Search

    O. Cref; I. Trestian; R. Tudoran; L. Cret; L. Vacariu

    2008-01-01

    In the last years the interest for magnetic stimulation of the human nervous tissue has increased, because this technique has proved its utility and applicability both as a diagnostic and as a treatment instrument. Research in this domain is aimed at eliminating some disadvantages of the technique: the lack of focalization of the stimulated human body region and the reduced

  3. Transcranial Magnetic Stimulation during Positron Emission Tomography: A New Method for Studying Connectivity of the Human Cerebral Cortex

    Microsoft Academic Search

    Robert Jech; Christopher J. Thompson; Roch Comeau; Terry Peters; Alan C. Evans

    1997-01-01

    We describe a new technique permitting the mapping of neural connections in the living human brain. The method combines two well established tools of brain research: transcranial mag- netic stimulation (TMS) and positron emission tomography (PET). We use TMS to stimulate directly a selected cortical area while simultaneously measuring changes in brain activity, in- dexed by cerebral blood flow (CBF),

  4. A mediating role of the auditory dorsal pathway in selective adaptation to speech: a state-dependent transcranial magnetic stimulation study.

    PubMed

    Grabski, Krystyna; Tremblay, Pascale; Gracco, Vincent L; Girin, Laurent; Sato, Marc

    2013-06-17

    In addition to sensory processing, recent neurobiological models of speech perception postulate the existence of a left auditory dorsal processing stream, linking auditory speech representations in the auditory cortex with articulatory representations in the motor system, through sensorimotor interaction interfaced in the supramarginal gyrus and/or the posterior part of the superior temporal gyrus. The present state-dependent transcranial magnetic stimulation study is aimed at determining whether speech recognition is indeed mediated by the auditory dorsal pathway, by examining the causal contribution of the left ventral premotor cortex, supramarginal gyrus and posterior part of the superior temporal gyrus during an auditory syllable identification/categorization task. To this aim, participants listened to a sequence of /ba/ syllables before undergoing a two forced-choice auditory syllable decision task on ambiguous syllables (ranging in the categorical boundary between /ba/ and /da/). Consistent with previous studies on selective adaptation to speech, following adaptation to /ba/, participants responses were biased towards /da/. In contrast, in a control condition without prior auditory adaptation no such bias was observed. Crucially, compared to the results observed without stimulation, single-pulse transcranial magnetic stimulation delivered at the onset of each target stimulus interacted with the initial state of each of the stimulated brain area by enhancing the adaptation effect. These results demonstrate that the auditory dorsal pathway contribute to auditory speech adaptation. PMID:23542585

  5. Acoustic evaluation of short-term effects of repetitive transcranial magnetic stimulation on motor aspects of speech in Parkinson's disease.

    PubMed

    Eliasova, I; Mekyska, J; Kostalova, M; Marecek, R; Smekal, Z; Rektorova, I

    2013-04-01

    Hypokinetic dysarthria in Parkinson's disease (PD) can be characterized by monotony of pitch and loudness, reduced stress, variable rate, imprecise consonants, and a breathy and harsh voice. Using acoustic analysis, we studied the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) applied over the primary orofacial sensorimotor area (SM1) and the left dorsolateral prefrontal cortex (DLPFC) on motor aspects of voiced speech in PD. Twelve non-depressed and non-demented men with PD (mean age 64.58 ± 8.04 years, mean PD duration 10.75 ± 7.48 years) and 21 healthy age-matched men (a control group, mean age 64 ± 8.55 years) participated in the speech study. The PD patients underwent two sessions of 10 Hz rTMS over the dominant hemisphere with 2,250 stimuli/day in a random order: (1) over the SM1; (2) over the left DLPFC in the "on" motor state. Speech examination comprised the perceptual rating of global speech performance and an acoustic analysis based upon a standardized speech task. The Mann-Whitney U test was used to compare acoustic speech variables between controls and PD patients. The Wilcoxon test was used to compare data prior to and after each stimulation in the PD group. rTMS applied over the left SM1 was associated with a significant increase in harmonic-to-noise ratio and net speech rate in the sentence tasks. With respect to the vowel task results, increased median values and range of Teager-Kaiser energy operator, increased vowel space area, and significant jitter decrease were observed after the left SM1 stimulation. rTMS over the left DLPFC did not induce any significant effects. The positive results of acoustic analysis were not reflected in a subjective rating of speech performance quality as assessed by a speech therapist. Our pilot results indicate that one session of rTMS applied over the SM1 may lead to measurable improvement in voice quality and intensity and an increase in speech rate and tongue movements. Nevertheless, these changes were not accompanied by changes in a perceptual evaluation of speech performance by a speech therapist. Future placebo-controlled studies in larger patient cohorts should verify if rTMS would be clinically useful for treating hypokinetic dysarthria in PD. PMID:23254927

  6. A new measure of cortical inhibition by mechanomyography and paired-pulse transcranial magnetic stimulation in unanesthetized rats.

    PubMed

    Hsieh, Tsung-Hsun; Dhamne, Sameer C; Chen, Jia-Jin J; Pascual-Leone, Alvaro; Jensen, Frances E; Rotenberg, Alexander

    2012-02-01

    Paired-pulse transcranial magnetic stimulation (ppTMS) is a safe and noninvasive tool for measuring cortical inhibition in humans, particularly in patients with disorders of cortical inhibition such as epilepsy. However, ppTMS protocols in rodent disease models, where mechanistic insight into the ppTMS physiology and into disease processes may be obtained, have been limited due to the requirement for anesthesia and needle electromyography. To eliminate the confounding factor of anesthesia and to approximate human ppTMS protocols in awake rats, we adapted the mechanomyogram (MMG) method to investigate the ppTMS inhibitory phenomenon in awake rats and then applied differential pharmacology to test the hypothesis that long-interval cortical inhibition is mediated by the GABA(A) receptor. Bilateral hindlimb-evoked MMGs were elicited in awake rats by long-interval ppTMS protocols with 50-, 100-, and 200-ms interstimulus intervals. Acute changes in ppTMS-MMG were measured before and after intraperitoneal injections of saline, the GABA(A) agonist pentobarbital (PB), and GABA(A) antagonist pentylenetetrazole (PTZ). An evoked MMG was obtained in 100% of animals by single-pulse stimulation, and ppTMS resulted in predictable inhibition of the test-evoked MMG. With increasing TMS intensity, MMG amplitudes increased in proportion to machine output to produce reliable input-output curves. Simultaneous recordings of electromyography and MMG showed a predictable latency discrepancy between the motor-evoked potential and the evoked MMG (7.55 ± 0.08 and 9.16 ± 0.14 ms, respectively). With pharmacological testing, time course observations showed that ppTMS-MMG inhibition was acutely reduced following PTZ (P < 0.05), acutely enhanced after PB (P < 0.01) injection, and then recovered to pretreatment baseline after 1 h. Our data support the application of the ppTMS-MMG technique for measuring the cortical excitability in awake rats and provide the evidence that GABA(A) receptor contributes to long-interval paired-pulse cortical inhibition. Thus ppTMS-MMG appears a well-tolerated biomarker for measuring GABA(A)-mediated cortical inhibition in rats. PMID:22013238

  7. Dorsolateral prefrontal transcranial magnetic stimulation in patients with major depression locally affects alpha power of REM sleep.

    PubMed

    Pellicciari, Maria Concetta; Cordone, Susanna; Marzano, Cristina; Bignotti, Stefano; Gazzoli, Anna; Miniussi, Carlo; De Gennaro, Luigi

    2013-01-01

    Sleep alterations are among the most important disabling manifestation symptoms of Major Depression Disorder (MDD). A critical role of sleep importance is also underlined by the fact that its adjustment has been proposed as an objective marker of clinical remission in MDD. Repetitive transcranial magnetic stimulation (rTMS) represents a relatively novel therapeutic tool for the treatment of drug-resistant depression. Nevertheless, besides clinical evaluation of the mood improvement after rTMS, we have no clear understanding of what are the neurophysiological correlates of such treatment. One possible marker underlying the clinical outcome of rTMS in MDD could be cortical changes on wakefulness and sleep activity. The aim of this open-label study was to evaluate the efficacy of a sequential bilateral rTMS treatment over the dorsolateral prefrontal cortex (DLPFC) to improve the mood in MDD patients, and to determine if rTMS can induce changes on the sleep structure, and if those changes can be used as a surrogate marker of the clinical state of the patient. Ten drug-resistant depressed patients participated to ten daily sessions of sequential bilateral rTMS with a low-frequency TMS (1 Hz) over right-DLPFC and a subsequent high-frequency (10 Hz) TMS over left-DLPFC. The clinical and neurophysiological effects induced by rTMS were evaluated, respectively by means of the Hamilton Depression Rating Scale (HDRS), and by comparing the sleep pattern modulations and the spatial changes of EEG frequency bands during both NREM and REM sleep, before and after the real rTMS treatment. The sequential bilateral rTMS treatment over the DLPFC induced topographical-specific decrease of the alpha activity during REM sleep over left-DLPFC, which is significantly associated to the clinical outcome. In line with the notion of a left frontal hypoactivation in MDD patients, the observed local decrease of alpha activity after rTMS treatment during the REM sleep suggests that alpha frequency reduction could be considered as a marker of up-regulation of cortical activity induced by rTMS, as well as a surrogate neurophysiological correlate of the clinical outcome. PMID:23935577

  8. Repetitive transcranial magnetic stimulation versus electroconvulsive therapy for major depression: a systematic review and meta-analysis.

    PubMed

    Ren, Juanjuan; Li, Hui; Palaniyappan, Lena; Liu, Hongmei; Wang, Jijun; Li, Chunbo; Rossini, Paolo Maria

    2014-06-01

    Electroconvulsive therapy (ECT) is the most effective treatment of depression. During the last decades repetitive transcranial magnetic stimulation (rTMS), an alternative method using electric stimulation of the brain, has revealed possible alternative to ECT in the treatment of depression. There are some clinical trials comparing their efficacies and safeties but without clear conclusions, mainly due to their small sample sizes. In the present study, a meta-analysis had been carried out to gain statistical power. Outcomes were response, remission, acceptability and cognitive effects in depression. Following a comprehensive literature search that included both English and Chinese language databases, we identified all randomized controlled trials that directly compared rTMS and ECT for major depression. 10 articles (9 trials) with a total of 425 patients were identified. Methodological quality, heterogeneity, sensitivity and publication bias were systematically evaluated. ECT was superior to high frequency rTMS in terms of response (64.4% vs. 48.7%, RR = 1.41, p = 0.03), remission (52.9% vs. 33.6%, RR = 1.38, p = 0.006) while discontinuation was not significantly different between the two treatments (8.3% vs. 9.4%, RR = 1.11, p = 0.80). According to the subgroup analysis, the superiority of ECT was more apparent in those with psychotic depression, while high frequency rTMS was as effective as ECT in those with non-psychotic depression. The same results were obtained in the comparison of ECT with low frequency rTMS. ECT had a non-significant advantage over high frequency rTMS on the overall improvement in HAMD scores (p = 0.11). There was insufficient data on medium or long term efficacy. Both rTMS and ECT were well tolerated with only minor side effects reported. Results based on 3 studies suggested that specific cognitive domains such as visual memory and verbal fluency were more impaired in patients receiving ECT. In conclusion, ECT seemed more effective than and at least as acceptable as rTMS in the short term, especially in the presence of psychotic depression. This review identified the lack of good quality trials comparing the long-term outcome and cognitive effects of rTMS and ECT, especially using approaches to optimize stimulus delivery and reduce clinical heterogeneity. PMID:24556538

  9. Utilizing repetitive transcranial magnetic stimulation to improve language function in stroke patients with chronic non-fluent aphasia.

    PubMed

    Garcia, Gabriella; Norise, Catherine; Faseyitan, Olufunsho; Naeser, Margaret A; Hamilton, Roy H

    2013-01-01

    Transcranial magnetic stimulation (TMS) has been shown to significantly improve language function in patients with non-fluent aphasia(1). In this experiment, we demonstrate the administration of low-frequency repetitive TMS (rTMS) to an optimal stimulation site in the right hemisphere in patients with chronic non-fluent aphasia. A battery of standardized language measures is administered in order to assess baseline performance. Patients are subsequently randomized to either receive real rTMS or initial sham stimulation. Patients in the real stimulation undergo a site-finding phase, comprised of a series of six rTMS sessions administered over five days; stimulation is delivered to a different site in the right frontal lobe during each of these sessions. Each site-finding session consists of 600 pulses of 1 Hz rTMS, preceded and followed by a picture-naming task. By comparing the degree of transient change in naming ability elicited by stimulation of candidate sites, we are able to locate the area of optimal response for each individual patient. We then administer rTMS to this site during the treatment phase. During treatment, patients undergo a total of ten days of stimulation over the span of two weeks; each session is comprised of 20 min of 1 Hz rTMS delivered at 90% resting motor threshold. Stimulation is paired with an fMRI-naming task on the first and last days of treatment. After the treatment phase is complete, the language battery obtained at baseline is repeated two and six months following stimulation in order to identify rTMS-induced changes in performance. The fMRI-naming task is also repeated two and six months following treatment. Patients who are randomized to the sham arm of the study undergo sham site-finding, sham treatment, fMRI-naming studies, and repeat language testing two months after completing sham treatment. Sham patients then cross over into the real stimulation arm, completing real site-finding, real treatment, fMRI, and two- and six-month post-stimulation language testing. PMID:23852365

  10. Combined noninvasive language mapping by navigated transcranial magnetic stimulation and functional MRI and its comparison with direct cortical stimulation.

    PubMed

    Ille, Sebastian; Sollmann, Nico; Hauck, Theresa; Maurer, Stefanie; Tanigawa, Noriko; Obermueller, Thomas; Negwer, Chiara; Droese, Doris; Zimmer, Claus; Meyer, Bernhard; Ringel, Florian; Krieg, Sandro M

    2015-07-01

    OBJECT Repetitive navigated transcranial magnetic stimulation (rTMS) is now increasingly used for preoperative language mapping in patients with lesions in language-related areas of the brain. Yet its correlation with intraoperative direct cortical stimulation (DCS) has to be improved. To increase rTMS's specificity and positive predictive value, the authors aim to provide thresholds for rTMS's positive language areas. Moreover, they propose a protocol for combining rTMS with functional MRI (fMRI) to combine the strength of both methods. METHODS The authors performed multimodal language mapping in 35 patients with left-sided perisylvian lesions by using rTMS, fMRI, and DCS. The rTMS mappings were conducted with a picture-to-trigger interval (PTI, time between stimulus presentation and stimulation onset) of either 0 or 300 msec. The error rates (ERs; that is, the number of errors per number of stimulations) were calculated for each region of the cortical parcellation system (CPS). Subsequently, the rTMS mappings were analyzed through different error rate thresholds (ERT; that is, the ER at which a CPS region was defined as language positive in terms of rTMS), and the 2-out-of-3 rule (a stimulation site was defined as language positive in terms of rTMS if at least 2 out of 3 stimulations caused an error). As a second step, the authors combined the results of fMRI and rTMS in a predefined protocol of combined noninvasive mapping. To validate this noninvasive protocol, they correlated its results to DCS during awake surgery. RESULTS The analysis by different rTMS ERTs obtained the highest correlation regarding sensitivity and a low rate of false positives for the ERTs of 15%, 20%, 25%, and the 2-out-of-3 rule. However, when comparing the combined fMRI and rTMS results with DCS, the authors observed an overall specificity of 83%, a positive predictive value of 51%, a sensitivity of 98%, and a negative predictive value of 95%. CONCLUSIONS In comparison with fMRI, rTMS is a more sensitive but less specific tool for preoperative language mapping than DCS. Moreover, rTMS is most reliable when using ERTs of 15%, 20%, 25%, or the 2-out-of-3 rule and a PTI of 0 msec. Furthermore, the combination of fMRI and rTMS leads to a higher correlation to DCS than both techniques alone, and the presented protocols for combined noninvasive language mapping might play a supportive role in the language-mapping assessment prior to the gold-standard intraoperative DCS. PMID:25748306

  11. Utilizing Repetitive Transcranial Magnetic Stimulation to Improve Language Function in Stroke Patients with Chronic Non-fluent Aphasia

    PubMed Central

    Garcia, Gabriella; Norise, Catherine; Faseyitan, Olufunsho; Naeser, Margaret A.; Hamilton, Roy H.

    2013-01-01

    Transcranial magnetic stimulation (TMS) has been shown to significantly improve language function in patients with non-fluent aphasia1. In this experiment, we demonstrate the administration of low-frequency repetitive TMS (rTMS) to an optimal stimulation site in the right hemisphere in patients with chronic non-fluent aphasia. A battery of standardized language measures is administered in order to assess baseline performance. Patients are subsequently randomized to either receive real rTMS or initial sham stimulation. Patients in the real stimulation undergo a site-finding phase, comprised of a series of six rTMS sessions administered over five days; stimulation is delivered to a different site in the right frontal lobe during each of these sessions. Each site-finding session consists of 600 pulses of 1 Hz rTMS, preceded and followed by a picture-naming task. By comparing the degree of transient change in naming ability elicited by stimulation of candidate sites, we are able to locate the area of optimal response for each individual patient. We then administer rTMS to this site during the treatment phase. During treatment, patients undergo a total of ten days of stimulation over the span of two weeks; each session is comprised of 20 min of 1 Hz rTMS delivered at 90% resting motor threshold. Stimulation is paired with an fMRI-naming task on the first and last days of treatment. After the treatment phase is complete, the language battery obtained at baseline is repeated two and six months following stimulation in order to identify rTMS-induced changes in performance. The fMRI-naming task is also repeated two and six months following treatment. Patients who are randomized to the sham arm of the study undergo sham site-finding, sham treatment, fMRI-naming studies, and repeat language testing two months after completing sham treatment. Sham patients then cross over into the real stimulation arm, completing real site-finding, real treatment, fMRI, and two- and six-month post-stimulation language testing. PMID:23852365

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

    PubMed

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

    2015-07-01

    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

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

    PubMed Central

    2014-01-01

    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

  14. Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory

    Microsoft Academic Search

    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

    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

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

    PubMed

    Freitas, Catarina; Pearlman, Chester; Pascual-Leone, Alvaro

    2012-02-01

    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 (BDI-II: 89% change, lasting 14 months along with weekly/bi-weekly maintenance treatments), but AVH remained unchanged. The patient also underwent a further course of the left temporo-parietal 1 Hz rTMS and amelioration of AVH severity was achieved (PSYRATS-AH: 53% change) and maintained at 1-year follow-up. AVH respond to rTMS in disorders other than schizophrenia. Furthermore, targeted rTMS to different brain regions can address diverse symptoms in neuropsychiatric conditions. PMID:21614723

  16. Significant analgesic effects of one session of postoperative left prefrontal cortex repetitive transcranial magnetic stimulation: A replication study

    PubMed Central

    Borckardt, Jeffrey J.; Reeves, Scott T.; Weinstein, Mitchel; Smith, Arthur R.; Shelley, Neal; Kozel, F. Andrew; Nahas, Ziad; Byrne, Karl T.; Morgan, Katherine; George, Mark S.

    2009-01-01

    Background In a recent preliminary trial in 20 patients after gastric bypass surgery, 20 minutes of repetitive transcranial magnetic stimulation (TMS) over the left prefrontal cortex was associated with a 40% reduction in postoperative patient-controlled morphine use. As is the case with all novel scientific findings, and especially those that might have an impact on clinical practice, replicability is paramount. This study sought to test this finding for replication and to more accurately estimate the effect size of this brief intervention on postoperative morphine use and postoperative pain and mood ratings. Methods Twenty participants who underwent gastric bypass surgery completed this replication and extension study. Beck Depression Inventory and Center for Epidemiological Studies Depression scale scores were collected befor surgery and at the time of discharge from the hospital. Immediately after surgery, participants were randomly assigned to receive 20 minutes of real or sham repetitive TMS (rTMS) (10 Hz, 10 seconds-ON, 20 seconds-OFF for a total of 4000 pulses). Patient-controlled morphine pump usage was tracked throughout each participant’s postoperative hospital stay. In addition, pain and mood ratings were collected via visual analogue scales twice per day. Results Findings from the original postoperative TMS trial were replicated, as cumulative morphine usage curves were significantly steeper among patients receiving sham TMS, and participants receiving real TMS had used 35% less morphine at the time of discharge than participants receiving sham TMS. At the time of discharge, subjects who had received real TMS had used 42.50 mg of morphine, whereas subjects receiving sham TMS had used an average of 64.88 mg. When the data from the original preliminary trial were combined with the data from this replication trial, a significant difference in cumulative morphine usage was observed between subjects receiving real and sham TMS. Overall, participants who received real TMS used 36% less morphine and had significantly lower ratings of postoperative pain-on-average, and pain-at-its-worst than participants receiving sham. In addition, participants who received real TMS rated their mood-at-its-worst as significantly better than participants receiving sham. The effect of a single 20-minute session of TMS on postoperative pain and morphine use appears to be large (Cohen’s d = 0.70) and clinically meaningful. Lastly, cross-lag correlational analyses indicate that improvements in mood follow improvements in pain by approximately 12 hours, supporting the notion that postoperative analgesic TMS effects are not driven by antidepressant effects. Conclusions Although more research is needed to verify these observed effects independently, findings from the original postoperative TMS trial were replicated. TMS may have the potential to significantly improve current standards of postoperative care among gastric bypass patients, and further studies may be warranted on other surgical populations. Future investigations should use methodology that permits more definitive conclusions about causal effects of TMS on postoperative pain (for example, double-blinding, sham stimulation that is matched with real TMS with respect to scalp discomfort). PMID:19759838

  17. 3390 IEEE TRANSACTIONS ON MAGNETICS, VOL. 39, NO. 5, SEPTEMBER 2003 The Effect of Transcranial Magnetic Stimulation on

    E-print Network

    Kawato, Suguru

    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

  18. Modulation of motor cortex excitability in the left hemisphere during action observation: a single- and paired-pulse transcranial magnetic stimulation study of self- and non-self-action observation

    Microsoft Academic Search

    Simone Patuzzo; Antonio Fiaschi; Paolo Manganotti

    2003-01-01

    Motor system excitability was tested by transcranial magnetic stimulation (TMS), and F-wave and H-reflex evaluation in different action observation tasks. Our aim was to investigate the effects produced by self- versus non-self-hand movement observation (MO). No significant differences were found between the self- and non-self-conditions. Movement observation significantly modulated motor cortex excitability, producing an increase in the amplitude of motor

  19. A deep dynamo generating Mercury's magnetic field

    NASA Astrophysics Data System (ADS)

    Christensen, Ulrich R.

    2006-12-01

    Mercury has a global magnetic field of internal origin and it is thought that a dynamo operating in the fluid part of Mercury's large iron core is the most probable cause. However, the low intensity of Mercury's magnetic field-about 1% the strength of the Earth's field-cannot be reconciled with an Earth-like dynamo. With the common assumption that Coriolis and Lorentz forces balance in planetary dynamos, a field thirty times stronger is expected. Here I present a numerical model of a dynamo driven by thermo-compositional convection associated with inner core solidification. The thermal gradient at the core-mantle boundary is subadiabatic, and hence the outer region of the liquid core is stably stratified with the dynamo operating only at depth, where a strong field is generated. Because of the planet's slow rotation the resulting magnetic field is dominated by small-scale components that fluctuate rapidly with time. The dynamo field diffuses through the stable conducting region, where rapidly varying parts are strongly attenuated by the skin effect, while the slowly varying dipole and quadrupole components pass to some degree. The model explains the observed structure and strength of Mercury's surface magnetic field and makes predictions that are testable with space missions both presently flying and planned.

  20. A deep dynamo generating Mercury's magnetic field.

    PubMed

    Christensen, Ulrich R

    2006-12-21

    Mercury has a global magnetic field of internal origin and it is thought that a dynamo operating in the fluid part of Mercury's large iron core is the most probable cause. However, the low intensity of Mercury's magnetic field--about 1% the strength of the Earth's field--cannot be reconciled with an Earth-like dynamo. With the common assumption that Coriolis and Lorentz forces balance in planetary dynamos, a field thirty times stronger is expected. Here I present a numerical model of a dynamo driven by thermo-compositional convection associated with inner core solidification. The thermal gradient at the core-mantle boundary is subadiabatic, and hence the outer region of the liquid core is stably stratified with the dynamo operating only at depth, where a strong field is generated. Because of the planet's slow rotation the resulting magnetic field is dominated by small-scale components that fluctuate rapidly with time. The dynamo field diffuses through the stable conducting region, where rapidly varying parts are strongly attenuated by the skin effect, while the slowly varying dipole and quadrupole components pass to some degree. The model explains the observed structure and strength of Mercury's surface magnetic field and makes predictions that are testable with space missions both presently flying and planned. PMID:17183319

  1. [Repetitive transcranial magnetic stimulation (rTMS) in the acute and long-term therapy of refractory depression--a case report].

    PubMed

    Smesny, S; Volz, H P; Liepert, J; Tauber, R; Hochstetter, A; Sauer, H

    2001-09-01

    We report on a patient with therapy-resistant major depression according to DSM-IV criteria who has been hospitalized for 60 months during the last 7 years. Not even five electroconvulsive therapy (ECT) series (61 single applications) brought lasting remission of symptoms. As cognitive deficits developed and prolonged postnarcotic recovery times were observed, further ECT was contraindicated. The left frontal cortex was chosen as the target site for repetitive transcranial magnetic stimulation (rTMS) treatment. For identification, a neuronavigational system was used that allows online monitoring of the position of the magnetic coil in relation to the individual cortex. The therapeutic progress was monitored by standardized psychiatric ratings (HAMD, BDI). In addition, cognitive performance was tested during the course of treatment. Only a few rTMS applications already caused an obvious brightening in mood, remission of depressive delusional symptoms, and an increase in personal interests and activities. After 4 weeks of daily treatment, the patient was discharged from the ward. The rTMS treatments and psychotherapeutic counseling have been continued on an outpatient basis. Thus, pharmaco- and psychotherapeutic interventions combined with rTMS led to persistent symptom remission and social reintegration. PMID:11572108

  2. Behavioral/Systems/Cognitive Deep Brain Stimulation of the Subthalamic Nucleus Alters

    E-print Network

    Aron, Adam

    Behavioral/Systems/Cognitive Deep Brain Stimulation of the Subthalamic Nucleus Alters the CorticalMRI, and transcranial magnetic stimulation studies, points to a specific brain system for stopping, including the right and reported an enhancement in the beta-band for NoGo compared to Go trials (Ku¨hn et al., 2004). These studies

  3. SEDMI - the Search for Extreme, Deep Magnetization Intensities

    NASA Astrophysics Data System (ADS)

    Foss, C. A.; Milligan, P. R.

    2013-12-01

    Shallow, high intensity magnetizations have prominent expressions in near-surface magnetic field measurements. Similar magnetizations at greater depth are less easily recognised. However, provided the field variations are not masked by those from shallower magnetizations, it is still possible to estimate their source parameters. This is in marked contrast to most other deep magnetizations, which are diffuse and produce less distinct magnetic field variations that carry less diagnostic source information. Analyses of depth to top of truncated intense magnetisations at basin unconformities provide reliable basins depth estimates, important for undercover mapping, and investigations of these magnetisations also has implications for study of tectonics, crustal architecture and higher levels of mineralisation. Anomalies are easily filtered to find those which might be due to intense, deep magnetizations. Depth to centre of a compact source is approximately equal to the diameter of its total gradient anomaly at half peak-amplitude, and also approximately three times the ratio of the peak total-gradient amplitude to the total magnetic intensity peak-to-trough amplitude. Both these relationships can be used to exclude anomalies from sources shallower than a minimum depth of interest, and jointly they provide a consistency check for a compact source. Accepted anomalies can then be further investigated by inversion. Although all magnetic field variations produced by deep magnetizations can also be explained by shallower, more diffuse magnetizations, the converse is not necessarily true, and inversion can eliminate some additional candidate anomalies. Small bodies at large depth are not detectable at surface; extreme magnetization intensities are likely to be exclusive to upper or mid-crustal rocks; and large bodies with extreme magnetization intensities are rare; so that resolving these sparse sources is of limited application to tasks such as Curie point isotherm mapping. However, these anomalies provide the most reliable information about magnetizations below about 10 km depth, and although they appear unremarkable near-surface, they become more prominent at higher elevations, as most field variations from shallower sources attenuate more rapidly. To develop a search process, we investigated five broad, circular to elliptic negative amplitude anomalies from sources beneath the Officer Basin in South Australia. These anomalies lie on a north-south swathe of just over 200 km, have amplitudes between 700 and 1700 nT, and half-peak total gradient widths of between 16 and 30 km. Magnetic moment analysis recovers north-westerly magnetizations with inclinations between +40° and +60°. These directions are supported by staged inversions of each anomaly, which also reveal depths to the top of the magnetizations of between 8 and 15 km, and magnetization intensities of between 5 and 29 Amp/m (actual magnetizations may be substantially stronger, occupying only a part of the model volume). Results are collated in the Australian Remanent Anomalies Database established by CSIRO and Geoscience Australia. When more fully populated, this database will provide a reference source of information on anomalies with particular properties, in this case those interpreted to be due to especially strong magnetizations below a certain depth.

  4. The Role of the Right Dorsolateral Prefrontal Cortex in Phasic Alertness: Evidence from a Contingent Negative Variation and Repetitive Transcranial Magnetic Stimulation Study

    PubMed Central

    Mannarelli, Daniela; Pauletti, Caterina; Grippo, Antonello; Amantini, Aldo; Augugliaro, Vito; Currà, Antonio; Missori, Paolo; Locuratolo, Nicoletta; De Lucia, Maria C.; Rinalduzzi, Steno; Fattapposta, Francesco

    2015-01-01

    Phasic alertness represents the ability to increase response readiness to a target following an external warning stimulus. Specific networks in the frontal and parietal regions appear to be involved in the alert state. In this study, we examined the role of the right dorsolateral prefrontal cortex (DLPFC) during the attentional processing of a stimulus using a cued double-choice reaction time task. The evaluation of these processes was conducted by means of Event-Related Potentials (ERPs), in particular by using the Contingent Negative Variation (CNV), and repetitive 1-Hz Transcranial Magnetic Stimulation (rTMS). Transient virtual inhibition of the right DLPFC induced by real 1-Hz rTMS stimulation led to a significant decrease in total CNV and W1-CNV areas if compared with the basal and post-sham rTMS conditions. Reaction times (RTs) did not decrease after inhibitory rTMS, but they did improve after sham stimulation. These results suggest that the right DLPFC plays a crucial role in the genesis and maintenance of the alerting state and learning processes.

  5. Meta-analysis of the effects of repetitive transcranial magnetic stimulation (rTMS) on negative and positive symptoms in schizophrenia

    PubMed Central

    Freitas, Catarina; Fregni, Felipe; Pascual-Leone, Alvaro

    2009-01-01

    Background A growing body of evidence suggests that repetitive transcranial magnetic stimulation (rTMS) can alleviate negative and positive symptoms of refractory schizophrenia. However, trials to date have been small and results are mixed. Methods We performed meta-analyses of all prospective studies of the therapeutic application of rTMS in refractory schizophrenia assessing the effects of high-frequency rTMS to the left dorsolateral prefrontal cortex (DLPFC) to treat negative symptoms, and low-frequency rTMS to the left temporo-parietal cortex (TPC) to treat auditory hallucinations (AH) and overall positive symptoms. Results When analyzing controlled (active arms) and uncontrolled studies together, the effect sizes showed significant and moderate effects of rTMS on negative and positive symptoms (based on PANSS-N or SANS, and PANSS-P or SAPS, respectively). However, the analysis for the sham-controlled studies revealed a small non-significant effect size for negative (0.27, p=0.417) and for positive symptoms (0.17, p=0.129). When specifically analyzing AH (based on AHRS, HCS or SAH), the effect size for the sham-controlled studies was large and significant (1.04; p=0.002). Conclusions These meta-analyses support the need for further controlled, larger trials to assess the clinical efficacy of rTMS on negative and positive symptoms of schizophrenia, while suggesting the need for exploration for alternative stimulation protocols. PMID:19138833

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

    PubMed Central

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

    2015-01-01

    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

  7. The Role of the Right Dorsolateral Prefrontal Cortex in Phasic Alertness: Evidence from a Contingent Negative Variation and Repetitive Transcranial Magnetic Stimulation Study.

    PubMed

    Mannarelli, Daniela; Pauletti, Caterina; Grippo, Antonello; Amantini, Aldo; Augugliaro, Vito; Currà, Antonio; Missori, Paolo; Locuratolo, Nicoletta; De Lucia, Maria C; Rinalduzzi, Steno; Fattapposta, Francesco

    2015-01-01

    Phasic alertness represents the ability to increase response readiness to a target following an external warning stimulus. Specific networks in the frontal and parietal regions appear to be involved in the alert state. In this study, we examined the role of the right dorsolateral prefrontal cortex (DLPFC) during the attentional processing of a stimulus using a cued double-choice reaction time task. The evaluation of these processes was conducted by means of Event-Related Potentials (ERPs), in particular by using the Contingent Negative Variation (CNV), and repetitive 1-Hz Transcranial Magnetic Stimulation (rTMS). Transient virtual inhibition of the right DLPFC induced by real 1-Hz rTMS stimulation led to a significant decrease in total CNV and W1-CNV areas if compared with the basal and post-sham rTMS conditions. Reaction times (RTs) did not decrease after inhibitory rTMS, but they did improve after sham stimulation. These results suggest that the right DLPFC plays a crucial role in the genesis and maintenance of the alerting state and learning processes. PMID:26090234

  8. Effect of low-frequency transcranial magnetic stimulation on an affective go/no-go task in patients with major depression: role of stimulation site and depression severity.

    PubMed

    Bermpohl, Felix; Fregni, Felipe; Boggio, Paulo S; Thut, Gregor; Northoff, Georg; Otachi, Patricia T M; Rigonatti, Sergio P; Marcolin, Marco A; Pascual-Leone, Alvaro

    2006-01-30

    Repetitive transcranial magnetic stimulation (rTMS) holds promise as a therapeutic tool in major depression. However, a means to assess the effects of a single rTMS session on mood to guide subsequent sessions would be desirable. The present study examined the effects of a single rTMS session on an affective go/no-go task known to measure emotional-cognitive deficits associated with major depression. Ten patients with an acute episode of unipolar major depression and eight partially or completely remitted (improved) patients underwent 1 Hz rTMS over the left and right dorsolateral prefrontal cortex prior to task performance. TMS over the mesial occipital cortex was used as a control. We observed significantly improved performance in depressed patients following right prefrontal rTMS. This beneficial effect declined with decreasing depression severity and tended to reverse in the improved group. Left prefrontal rTMS had no significant effect in the depressed group, but it resulted in impaired task performance in the improved group. Our findings indicate that the acute response of depressed patients to rTMS varies with the stimulation site and depression severity. Further studies are needed to determine whether the present paradigm could be used to predict antidepressant treatment success or to individualize stimulation parameters according to specific pathology. PMID:16352348

  9. Effects of repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex on the attentional processing of emotional information in major depression: a pilot study.

    PubMed

    Leyman, Lemke; De Raedt, Rudi; Vanderhasselt, Marie-Anne; Baeken, Chris

    2011-01-30

    Repetitive transcranial magnetic stimulation (rTMS) is as a promising therapeutic tool for major depressive disorder. However, the degree of clinical improvement following rTMS treatment still remains questionable. This pilot study aimed at investigating potential working mechanisms of rTMS by examining the effects on attentional processing towards negative information, a proposed underlying cognitive vulnerability factor for depression. The antidepressant effect of high-frequency (10 Hz) rTMS over the left dorsolateral prefrontal cortex and possible effects on the inhibitory processing of emotional information was assessed in a sample of 14 depressed patients immediately after the first stimulation session and at the end of a 2-week treatment period. One session of rTMS caused neither significant self-reported mood changes, nor improvements in inhibitory control towards negative information. After a 10-day treatment period, nine out of our 14 patients demonstrated significant mood improvements, as indexed by a reduction of more than 50% on the Hamilton depression rating scale. Responders also demonstrated significant improvements in the inhibitory processing of negative information. This study contributed to the existing evidence of the antidepressant effect of rTMS in the treatment of depression and additionally was able to demonstrate improvements in underlying deficiencies in inhibitory processes towards negative information. PMID:20510464

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

    PubMed Central

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

    2015-01-01

    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 33. To help improve this understanding, proton magnetic resonance spectroscopy (1H-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 35. In fact, a recent study demonstrated that 1H-MRS is indeed a powerful means to better understand the effects of tDCS on neurotransmitter concentration 34. This article aims to describe the complete protocol for combining tDCS (NeuroConn MR compatible stimulator) with 1H-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 27,30,31. Methodological factors to consider and possible modifications to the protocol are also discussed. PMID:25490453

  11. Naming facilitation induced by transcranial direct current stimulation

    Microsoft Academic Search

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

    2010-01-01

    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

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

    PubMed Central

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

    2015-01-01

    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

  13. Right secondary somatosensory cortex-a promising novel target for the treatment of drug-resistant neuropathic orofacial pain with repetitive transcranial magnetic stimulation.

    PubMed

    Lindholm, Pauliina; Lamusuo, Salla; Taiminen, Tero; Pesonen, Ullamari; Lahti, Ari; Virtanen, Arja; Forssell, Heli; Hietala, Jarmo; Hagelberg, Nora; Pertovaara, Antti; Parkkola, Riitta; Jääskeläinen, Satu

    2015-07-01

    High-frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex has analgesic effect; however, the efficacy of other cortical targets and the mode of action remain unclear. We examined the effects of rTMS in neuropathic orofacial pain, and compared 2 cortical targets against placebo. Furthermore, as dopaminergic mechanisms modulate pain responses, we assessed the influence of the functional DRD2 gene polymorphism (957C>T) and the catechol-O-methyltransferase (COMT) Val158Met polymorphism on the analgesic effect of rTMS. Sixteen patients with chronic drug-resistant neuropathic orofacial pain participated in this randomized, placebo-controlled, crossover study. Navigated high-frequency rTMS was given to the sensorimotor (S1/M1) and the right secondary somatosensory (S2) cortices. All subjects were genotyped for the DRD2 957C>T and COMT Val158Met polymorphisms. Pain, mood, and quality of life were monitored throughout the study. The numerical rating scale pain scores were significantly lower after the S2 stimulation than after the S1/M1 (P = 0.0071) or the sham (P = 0.0187) stimulations. The Brief Pain Inventory scores were also lower 3 to 5 days after the S2 stimulation than those at pretreatment baseline (P = 0.0127 for the intensity of pain and P = 0.0074 for the interference of pain) or after the S1/M1 (P = 0.001 and P = 0.0001) and sham (P = 0.0491 and P = 0.0359) stimulations. No correlations were found between the genetic polymorphisms and the analgesic effect in the present small clinical sample. The right S2 cortex is a promising new target for the treatment of neuropathic orofacial pain with high-frequency rTMS. PMID:25830924

  14. fMRI-Guided transcranial magnetic stimulation reveals that the superior temporal sulcus is a cortical locus of the McGurk effect.

    PubMed

    Beauchamp, Michael S; Nath, Audrey R; Pasalar, Siavash

    2010-02-17

    A compelling example of auditory-visual multisensory integration is the McGurk effect, in which an auditory syllable is perceived very differently depending on whether it is accompanied by a visual movie of a speaker pronouncing the same syllable or a different, incongruent syllable. Anatomical and physiological studies in human and nonhuman primates have suggested that the superior temporal sulcus (STS) is involved in auditory-visual integration for both speech and nonspeech stimuli. We hypothesized that the STS plays a critical role in the creation of the McGurk percept. Because the location of multisensory integration in the STS varies from subject to subject, the location of auditory-visual speech processing in the STS was first identified in each subject with fMRI. Then, activity in this region of the STS was disrupted with single-pulse transcranial magnetic stimulation (TMS) as subjects rated their percept of McGurk and non-McGurk stimuli. Across three experiments, TMS of the STS significantly reduced the likelihood of the McGurk percept but did not interfere with perception of non-McGurk stimuli. TMS of the STS was effective at disrupting the McGurk effect only in a narrow temporal window from 100 ms before auditory syllable onset to 100 ms after onset, and TMS of a control location did not influence perception of McGurk or control stimuli. These results demonstrate that the STS plays a critical role in the McGurk effect and auditory-visual integration of speech. PMID:20164324

  15. Multiple blocks of intermittent and continuous theta-burst stimulation applied via transcranial magnetic stimulation differently affect sensory responses in rat barrel cortex

    PubMed Central

    Thimm, Andreas; Funke, Klaus

    2015-01-01

    Cortical sensory processing varies with cortical state and the balance of inhibition to excitation. Repetitive transcranial magnetic stimulation (rTMS) has been shown to modulate human cortical excitability. In a rat model, we recently showed that intermittent theta-burst stimulation (iTBS) applied to the corpus callosum, to activate primarily supragranular cortical pyramidal cells but fewer subcortical neurons, strongly reduced the cortical expression of parvalbumin (PV), indicating reduced activity of fast-spiking interneurons. Here, we used the well-studied rodent barrel cortex system to test how iTBS and continuous TBS (cTBS) modulate sensory responses evoked by either single or double stimuli applied to the principal (PW) and/or adjacent whisker (AW) in urethane-anaesthetized rats. Compared to sham stimulation, iTBS but not cTBS particularly enhanced late (>18 ms) response components of multi-unit spiking and local field potential responses in layer 4 but not the very early response (<18 ms). Similarly, only iTBS diminished the suppression of the second response evoked by paired PW or AW–PW stimulation at 20 ms intervals. The effects increased with each of the five iTBS blocks applied. With cTBS a mild effect similar to that of iTBS was first evident after 4–5 stimulation blocks. Enhanced cortical c-Fos and zif268 expression but reduced PV and GAD67 expression was found only after iTBS, indicating increased cortical activity due to lowered inhibition. We conclude that iTBS but less cTBS may primarily weaken a late recurrent-type cortical inhibition mediated via a subset of PV+ interneurons, enabling stronger late response components believed to contribute to the perception of sensory events. PMID:25504571

  16. Low frequency repetitive transcranial magnetic stimulation of the left dorsolateral prefrontal cortex transiently increases cue-induced craving for methamphetamine: A preliminary study

    PubMed Central

    Li, Xingbao; Malcolm, Robert J.; Huebner, Kristina; Hanlon, Colleen A.; Taylor, Joseph J.; Brady, Kathleen T.; George, Mark S.; See, Ronald E.

    2014-01-01

    Background Repetitive transcranial magnetic stimulation (rTMS) can temporarily interrupt or facilitate activity in a focal brain region. Several lines of evidence suggest that rTMS of the dorsolateral prefrontal cortex (DLPFC) can affect processes involved in drug addiction. We hypothesized that a single session of low-frequency rTMS of the left DLPFC would modulate cue-induced craving for methamphetamine (MA) when compared to a sham rTMS session. Methods In this single-blind, sham-controlled crossover study, 10 non-treatment seeking MA-dependent users and 8 healthy controls were randomized to receive 15 min of sham and real (1 Hz) DLPFC rTMS in two experimental sessions separated by 1 h. During each rTMS session, participants were exposed to blocks of neutral cues and MA-associated cues. Participants rated their craving after each cue block. Results In MA users, real rTMS over the left DLPFC increased self-reported craving as compared to sham stimulation (17.86 ± 1.46 vs. 24.85 ± 1.57, p = 0.001). rTMS had no effect on craving in healthy controls. One Hertz rTMS of the left DLPFC was safe and tolerable for all participants. Conclusions Low frequency rTMS of the left DLPFC transiently increased cue-induced craving in MA participants. These preliminary results suggest that 1 Hz rTMS of the left DLPFC may increase craving by inhibiting the prefrontal cortex or indirectly activating subcortical regions involved in craving. PMID:24028801

  17. Transcranial magnetic stimulation in mild to severe hemiparesis early after stroke: a proof of principle and novel approach to improve motor function.

    PubMed

    Conforto, Adriana B; Anjos, Sarah M; Saposnik, Gustavo; Mello, Eduardo A; Nagaya, Erina M; Santos, Waldyr; Ferreiro, Karina N; Melo, Eduardo S; Reis, Felipe I; Scaff, Milberto; Cohen, Leonardo G

    2012-07-01

    Low-frequency repetitive transcranial magnetic stimulation (rTMS) of the unaffected hemisphere can enhance function of the paretic hand in patients with mild motor impairment. Effects of low-frequency rTMS to the contralesional motor cortex at an early stage of mild to severe hemiparesis after stroke are unknown. In this pilot, randomized, double-blind clinical trial we compared the effects of low-frequency rTMS or sham rTMS as add-on therapies to outpatient customary rehabilitation, in 30 patients within 5-45 days after ischemic stroke, and mild to severe hand paresis. The primary feasibility outcome was compliance with the interventions. The primary safety outcome was the proportion of intervention-related adverse events. Performance of the paretic hand in the Jebsen-Taylor test and pinch strength were secondary outcomes. Outcomes were assessed at baseline, after ten sessions of treatment administered over 2 weeks and at 1 month after end of treatment. Baseline clinical features were comparable across groups. For the primary feasibility outcome, compliance with treatment was 100% in the active group and 94% in the sham group. There were no serious intervention-related adverse events. There were significant improvements in performance in the Jebsen-Taylor test (mean, 12.3% 1 month after treatment) and pinch force (mean, 0.5 Newtons) in the active group, but not in the sham group. Low-frequency rTMS to the contralesional motor cortex early after stroke is feasible, safe and potentially effective to improve function of the paretic hand, in patients with mild to severe hemiparesis. These promising results will be valuable to design larger randomized clinical trials. PMID:22173953

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

    PubMed

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

    2004-01-15

    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

  19. Cathodal Transcranial Direct Current Stimulation of the Right Wernicke's Area Improves Comprehension in Subacute Stroke Patients

    ERIC Educational Resources Information Center

    You, Dae Sang; Kim, Dae-Yul; Chun, Min Ho; Jung, Seung Eun; Park, Sung Jong

    2011-01-01

    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…

  20. Effects of transcranial direct current stimulation on working memory in patients with Parkinson's disease

    Microsoft Academic Search

    Paulo S. Boggio; Roberta Ferrucci; Sergio P. Rigonatti; Priscila Covre; Michael Nitsche; Alvaro Pascual-Leone; Felipe Fregni

    2006-01-01

    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

  1. Effects of transcranial direct current stimulation coupled with repetitive electrical stimulation on cortical spreading depression

    Microsoft Academic Search

    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

    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

  2. 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

    PubMed Central

    Menkes, D.; Bodnar, P.; Ballesteros, R.; Swenson, M.

    1999-01-01

    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 the hypothesis that right frontal SF r-TMS would treat depressed patients with minimal effect on controls.? A psychiatrist administered the Beck depression inventory and Hamilton D depression rating scales to eight depressed patients and six controls before and after the treatment protocol. Eight sessions of 100 right frontal lobe SF r-TMS were given at motor threshold and 0.5 Hz over a 6 week period. No adverse outcomes were noted in either group. A significant antidepressant effect was noted in depressed patients on the Beck and Hamilton D depression rating scales (p<0.05). No change on either scale was noted in the controls. In conclusion right frontal lobe SF r-TMS is a safe, non-invasive treatment for major depression that deserves further investigation.?? PMID:10369835

  3. 21. PALEOMAGNETISM AND ROCK MAGNETIC PROPERTIES OF GABBRO FROM HOLE 894G, HESS DEEP1

    Microsoft Academic Search

    Janet E. Pariso; Paul Kelso; Carl Richter

    Results of paleomagnetic and rock magnetic measurements are presented from gabbroic samples recovered during Ocean Drilling Program Leg 147 at the Hess Deep. Paleomagnetic measurements indicate that samples acquired up to two small com- ponents of secondary remanent magnetization. Stable magnetic inclinations determined after alternating-field and thermal demagnetization reveal a mean stable magnetic direction (38°) that is significantly steeper than

  4. 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

    Kim, Yong Kyun; Shin, Sung Hun

    2014-01-01

    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

  5. Efficacy and safety of the Chinese herbal medicine shuganjieyu with and without adjunctive repetitive transcranial magnetic stimulation (rTMS) for geriatric depression: a randomized controlled trial

    PubMed Central

    XIE, Minmin; JIANG, Wenhai; YANG, Haibo

    2015-01-01

    Background Pharmacological treatment of geriatric depression is often ineffective because patients cannot tolerate adequate doses of antidepressant medications. Aim Examine the efficacy and safety of shuganjieyu – the first Chinese herbal medicine approved for the treatment of depression by China’s drug regulatory agency -- with and without adjunctive treatment with repetitive transcranial magnetic stimulation (rTMS) in the treatment of geriatric depression. Methods Sixty-five inpatients 60 or older who met ICD-10 criteria for depression were randomly assigned to an experimental group (shuganjieyu + rTMS) (n=36) or a control group (shuganjieyu + sham rTMS)(n=29). All participants received 4 capsules of shuganjieyu daily for 6 weeks. rTMS (or sham rTMS) was administered 20 minutes daily, five days a week for 4 weeks. Blinded raters used the Hamilton Rating Scale for Depression (HAMD-17) and the Treatment Emergent Symptom Scale to assess clinical efficacy and safety at baseline and 1, 2, 4, and 6 weeks after starting treatment. Over the six-week trial, there was only one dropout from the experimental group and two dropouts from the control group. Results None of the patients had serious side effects, but 40% in the experimental group and 50% in the control group experienced minor side effects that all resolved spontaneously. Both groups showed substantial stepwise improvement in depressive symptoms over the 6 weeks. Repeated measures ANOVA found no differences between the two groups. After 6 weeks, 97% of the experimental group had experienced a 25% or greater drop in the level of depression, but only 20% had experience a 50% or greater drop in the level of depression; the corresponding values in the control group were 96% and 19%. There were some minor, non-significant differences in the onset of the treatment effect between the different types of depressive symptoms, but by the second week of treatment all five HAMD-17 subscale scores had improved significantly in both groups Conclusion The Chinese herbal medicine shuganjieyu is effective and safe in the treatment of geriatric depression, but only a minority of patients have greater than 50% improvement in their depressive symptoms after 6 weeks of treatment. Adjunctive use of rTMS with shuganjieyu does not improve the overall outcome and does not significantly speed up the onset of action of shuganjieyu.

  6. Low-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) Modulates Evoked-Gamma Frequency Oscillations in Autism Spectrum Disorder (ASD)

    PubMed Central

    Baruth, Joshua M.; Casanova, Manuel F.; El-Baz, Ayman; Horrell, Tim; Mathai, Grace; Sears, Lonnie; Sokhadze, Estate

    2010-01-01

    Introduction It has been reported that individuals with Autism Spectrum Disorder (ASD) have abnormal reactions to the sensory environment and visuo-perceptual abnormalities. Electrophysiological research has provided evidence that gamma band activity (30-80 Hz) is a physiological indicator of the co-activation of cortical cells engaged in processing visual stimuli and integrating different features of a stimulus. A number of studies have found augmented and indiscriminative gamma band power at early stages of visual processing in ASD; this may be related to decreased inhibitory processing and an increase in the ratio of cortical excitation to inhibition. Low frequency or ‘slow’ (?1HZ) repetitive transcranial magnetic stimulation (rTMS) has been shown to increase inhibition of stimulated cortex by the activation of inhibitory circuits. Methods We wanted to test the hypothesis of gamma band abnormalities at early stages of visual processing in ASD by investigating relative evoked (i.e. ~ 100 ms) gamma power in 25 subjects with ASD and 20 age-matched controls using Kanizsa illusory figures. Additionally, we wanted to assess the effects of 12 sessions of bilateral ‘slow’ rTMS to the dorsolateral prefrontal cortex (DLPFC) on evoked gamma activity using a randomized controlled design. Results In individuals with ASD evoked gamma activity was not discriminative of stimulus type, whereas in controls early gamma power differences between target and non-target stimuli were highly significant. Following rTMS individuals with ASD showed significant improvement in discriminatory gamma activity between relevant and irrelevant visual stimuli. We also found significant improvement in the responses on behavioral questionnaires (i.e., irritability, repetitive behavior) as a result of rTMS. Conclusion We proposed that ‘slow’ rTMS may have increased cortical inhibitory tone which improved discriminatory gamma activity at early stages of visual processing. rTMS has the potential to become an important therapeutic tool in ASD treatment and has shown significant benefits in treating core symptoms of ASD with few, if any side effects. PMID:21116441

  7. Transcranial focused ultrasound as a possible treatment for major depression.

    PubMed

    Tsai, Shih-Jen

    2015-04-01

    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

  8. Cranial electrotherapy stimulation and transcranial pulsed current stimulation: a computer based high-resolution modeling study.

    PubMed

    Datta, Abhishek; Dmochowski, Jacek P; Guleyupoglu, Berkan; Bikson, Marom; Fregni, Felipe

    2013-01-15

    The field of non-invasive brain stimulation has developed significantly over the last two decades. Though two techniques of noninvasive brain stimulation--transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS)--are becoming established tools for research in neuroscience and for some clinical applications, related techniques that also show some promising clinical results have not been developed at the same pace. One of these related techniques is cranial electrotherapy stimulation (CES), a class of transcranial pulsed current stimulation (tPCS). In order to understand further the mechanisms of CES, we aimed to model CES using a magnetic resonance imaging (MRI)-derived finite element head model including cortical and also subcortical structures. Cortical electric field (current density) peak intensities and distributions were analyzed. We evaluated different electrode configurations of CES including in-ear and over-ear montages. Our results confirm that significant amounts of current pass the skull and reach cortical and subcortical structures. In addition, depending on the montage, induced currents at subcortical areas, such as midbrain, pons, thalamus and hypothalamus are of similar magnitude than that of cortical areas. Incremental variations of electrode position on the head surface also influence which cortical regions are modulated. The high-resolution modeling predictions suggest that details of electrode montage influence current flow through superficial and deep structures. Finally we present laptop based methods for tPCS dose design using dominant frequency and spherical models. These modeling predictions and tools are the first step to advance rational and optimized use of tPCS and CES. PMID:23041337

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

    Microsoft Academic Search

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

    2011-01-01

    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

  10. Treatments in context: transcranial direct current brain stimulation as a potential treatment in pediatric psychosis

    PubMed Central

    David, Christopher N; Rapoport, Judith L; Gogtay, Nitin

    2014-01-01

    Childhood-onset schizophrenia is a chronic, severe form of schizophrenia, and is typically treatment resistant. Even after optimized pharmacotherapy, a majority (over 70%) of these pediatric patients present lasting psychotic symptoms and impaired cognition, necessitating the need for novel treatment modalities. Recent work in transcranial magnetic stimulation suggests moderate efficacy in symptom reduction in adult patients with schizophrenia; however, the transcranial magnetic stimulation treatment is cumbersome for this severely ill population. Transcranial direct current stimulation may provide a safe and effective adjuvant treatment for continued residual symptoms of schizophrenia. PMID:23545058

  11. Language Lateralization in Children Using Functional Transcranial Doppler Sonography

    ERIC Educational Resources Information Center

    Haag, Anja; Moeller, Nicola; Knake, Susanne; Hermsen, Anke; Oertel, Wolfgang H.; Rosenow, Felix; Hamer, Hajo M.

    2010-01-01

    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…

  12. Complications of three deep sedation methods for magnetic resonance imaging

    PubMed Central

    Tith, Solina; Lalwani, Kirk; Fu, Rongwei

    2012-01-01

    Background: Propofol and pentobarbital are commonly used to sedate children undergoing magnetic resonance imaging (MRI). Aim/Objective: To compare the safety of three types of sedation: intravenous propofol (PROP), mixed pentobarbital/propofol (PENT), and mixed pentobarbital group requiring supplemental sedation (PENT SUPP) regimens in pediatric patients following deep sedation (DS) for noncardiac MRI. Materials and Methods: We conducted a case-control study matching 619 cases with complications with 619 controls using data from our institution's sedation database for children deeply sedated for noncardiac MRI. Cases were defined as patients with any complication and we characterized complications from cases, and used a conditional logistic regression model to assess the association between three DS methods and occurrence of complications after adjusting for confounding variables. Results: We found that complications occurred in association with 794 (10.1%) of the 7,839 DSs performed for MRI between 1998 and 2008. Of the 794 cases, 619 cases met inclusion criteria for the study. Among the 619 cases that met inclusion criteria, 24 (0.3% of 7,839 DSs total) were associated with major complications. Type of sedation was significantly associated with the occurrence of complications, and the PENT group was associated with decreased odds of complications when compared to the PROP regimen (OR 0.68; 95% CI 0.46, 0.98; P=0.040) and compared to the PENT SUPP group (OR 0.60; 95% CI 0.31, 0.89; P<0.0001). Conclusions: DS with a pentobarbital technique was associated with decreased odds for complications when compared to a propofol-based technique or a pentobarbital technique requiring supplemental sedation. PMID:22557739

  13. Transcranial direct current stimulation applied over the somatosensory cortex – Differential effect on low and high frequency SEPs

    Microsoft Academic Search

    Anne Dieckhöfer; Till Dino Waberski; Michael Nitsche; Walter Paulus; Helmut Buchner; René Gobbelé

    2006-01-01

    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.

  14. Magnetic field effect on tunnel ionization of deep impurities by terahertz radiation S.D. Ganichev1

    E-print Network

    Ganichev, Sergey

    Magnetic field effect on tunnel ionization of deep impurities by terahertz radiation S.D. Ganichev1-Technical Institute, St. Petersburg, Russia Abstract: A suppression of tunnelling ionization of deep impurities magnetic fields. Overview Tunneling ionization of deep centers in the terahertz field of high-intensity far

  15. Laser scattering by transcranial rat brain illumination

    NASA Astrophysics Data System (ADS)

    Sousa, Marcelo V. P.; Prates, Renato; Kato, Ilka T.; Sabino, Caetano P.; Suzuki, Luis C.; Ribeiro, Martha S.; Yoshimura, Elisabeth M.

    2012-06-01

    Due to the great number of applications of Low-Level-Laser-Therapy (LLLT) in Central Nervous System (CNS), the study of light penetration through skull and distribution in the brain becomes extremely important. The aim is to analyze the possibility of precise illumination of deep regions of the rat brain, measure the penetration and distribution of red (? = 660 nm) and Near Infra-Red (NIR) (? = 808 nm) diode laser light and compare optical properties of brain structures. The head of the animal (Rattus Novergicus) was epilated and divided by a sagittal cut, 2.3 mm away from mid plane. This section of rat's head was illuminated with red and NIR lasers in points above three anatomical structures: hippocampus, cerebellum and frontal cortex. A high resolution camera, perpendicularly positioned, was used to obtain images of the brain structures. Profiles of scattered intensities in the laser direction were obtained from the images. There is a peak in the scattered light profile corresponding to the skin layer. The bone layer gives rise to a valley in the profile indicating low scattering coefficient, or frontal scattering. Another peak in the region related to the brain is an indication of high scattering coefficient (?s) for this tissue. This work corroborates the use of transcranial LLLT in studies with rats which are subjected to models of CNS diseases. The outcomes of this study point to the possibility of transcranial LLLT in humans for a large number of diseases.

  16. Premotor transcranial direct current stimulation (tDCS) affects primary motor excitability in humans

    Microsoft Academic Search

    Klára Boros; Csaba Poreisz; Alexander Münchau; Walter Paulus; Michael A. Nitsche

    2008-01-01

    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,

  17. Short and long-lasting tinnitus relief induced by transcranial direct current stimulation

    Microsoft Academic Search

    Pierre GarinChantal; Chantal Gilain; Jean-Philippe Van Damme; Katalin de Fays; Jacques Jamart; Michel Ossemann; Yves Vandermeeren

    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

  18. Transcranial sonography (TCS) of brain parenchyma in movement disorders: quality standards, diagnostic applications and novel technologies.

    PubMed

    Walter, U; Školoudík, D

    2014-08-01

    Transcranial B-mode sonography (TCS) of brain parenchyma is being increasingly used as a diagnostic tool in movement disorders. Compared to other neuroimaging modalities such as magnetic resonance imaging (MRI) and computed tomography, TCS can be performed today with portable machines and has the advantages of noninvasiveness and high resistance to movement artifacts. In distinct brain disorders TCS detects abnormalities that cannot be visualized or can only be visualized with significant effort with other imaging methods. In the field of movement disorders, TCS has been established mainly as a tool for the early and differential diagnosis of Parkinson's disease. The postoperative position control of deep brain stimulation electrodes, especially in the subthalamic nucleus, can reliably and safely be performed with TCS.? The present update review summarizes the current methodological standards and defines quality criteria of adequate TCS imaging and assessment of diagnostically relevant deep brain structures such as substantia nigra, brainstem raphe, basal ganglia and ventricles. Finally, an overview is given on recent technological advances including TCS-MRI fusion imaging and upcoming technologies of digitized image analysis aiming at a more investigator-independent assessment of deep brain structures on TCS. PMID:24764215

  19. Estimation of the iron loss in deep-sea permanent magnet motors considering seawater compressive stress.

    PubMed

    Xu, Yongxiang; Wei, Yanyu; Zou, Jibin; Li, Jianjun; Qi, Wenjuan; Li, Yong

    2014-01-01

    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

  20. Estimation of the Iron Loss in Deep-Sea Permanent Magnet Motors considering Seawater Compressive Stress

    PubMed Central

    Wei, Yanyu; Zou, Jibin; Li, Jianjun; Qi, Wenjuan; Li, Yong

    2014-01-01

    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

  1. Magnetic Properties of the Lower Oceanic Crust from Hess Deep (IODP Expedition 345)

    NASA Astrophysics Data System (ADS)

    Friedman, S. A.; Morris, A.; Horst, A. J.

    2014-12-01

    Hess Deep is located at a tectonic window created by rifting of the Cocos-Nazca into East Pacific Rise crust. IODP Expedition 345 drilled into this window to recover lower oceanic crust primitive plutonic rock lithologies such as gabbros, troctolites, and olivine gabbronorites. Differences in ferromagnetic carriers impact the ferromagnetic properties and the contribution of oceanic crust to magnetic anomalies. 57 samples have been magnetically examined using low-temperature magnetic remanence, hysteresis properties, and low field susceptibility. Results show varying properties based on lithology and alteration processes. Secondary processes such as metamorphism, hydrothermal alteration and cataclasis can alter the magnetic history and properties of these once primitive rocks. The least altered samples consistently show pure stiochemetric magnetic magnetite as the main ferromagnetic carrier. Whereas, altered samples may contain multiple ferromagnetic carriers, such as pyrrhotite and magnetite.

  2. Assessing the Deep Interior Dynamics and Magnetism of A-type Stars

    NASA Astrophysics Data System (ADS)

    Featherstone, Nicholas A.; Browning, Matthew K.; Brun, Allan Sacha; Toomre, Juri

    2011-01-01

    A-type stars have both a shallow near-surface zone of fast convection that can excite acoustic modes and a deep zone of core convection whose properties may be studied through asteroseismology. Many A stars also exhibit large magnetic spots as they rotate. We have explored the properties of core convection in rotating A-type stars and their ability to build strong magnetic fields. These 3-D simulations using the ASH code may serve to inform asteroseismic deductions of interior rotation and magnetism that are now becoming feasible. Our models encompass the inner 30% by radius of a 2 solar mass A-type star, capturing both the convective core and some of the overlying radiative envelope. Convection can drive a column of strong retrograde differential rotation and yield a core prolate in shape. When dynamo action is admitted, the convection is able to generate strong magnetic fields largely in equipartition with the dynamics. Introducing a modest external field (which may be of primordial origin) into the radiative envelope can substantially alter the turbulent dynamics of the convective core, yielding magnetic fields of remarkable super-equipartition strength. The turbulent convection involves a complex assembly of helical rolls that link distant portions of the core and stretch and advect magnetic field into broad swathes of strong toroidal field. These simulations reveal that supercomputing is providing a perspective of the deep dynamics that may become testable with asteroseismology for these stars.

  3. Exploring the deep convection and magnetism of A-type stars

    NASA Astrophysics Data System (ADS)

    Featherstone, Nicholas A.; Browning, Matthew K.; Brun, Allan Sacha; Toomre, Juri

    2011-08-01

    A-type stars have both a near-surface layer of fast convection that can excite acoustic modes and a deep zone of core convection whose properties may be probed with asteroseismology. Many A-type stars also exhibit large magnetic spots that are often attributed to surviving primordial fields of global scale in the intervening radiative zone. We have explored the potential for core convection in rotating A-type stars to build strong magnetic fields through dynamo action. These 3-D simulations using the ASH code provide guidance on the nature of differential rotation and magnetic fields that may be present in the deep interiors of these stars, thus informing the asteroseismic deductions now becoming feasible. Our models encompass the inner 30% by radius of a two solar mass A-type star, rotating at four times the solar rate and capturing the convective core and a portion of the overlying radiative envelope. Convection in these stars drives a strong retrograde differential rotation and yields a core that is prolate in shape. When dynamo action is admitted, the convection generates strong magnetic fields largely in equipartition with the dynamics. Remarkably, introducing a modest but large-scale external field threading the radiative envelope (which may be of primordial origin) can substantially alter the turbulent dynamics of the convective interior. The resulting convection involves a complex assembly of helical rolls that link distant portions of the core and stretch and advect magnetic field, ultimately yielding magnetic fields of super-equipartition strength.

  4. Advances in transcranial doppler ultrasonography

    Microsoft Academic Search

    Georgios Tsivgoulis; Andrei V. Alexandrov; Michael A. Sloan

    2009-01-01

    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

  5. Short and long duration transcranial direct current stimulation (tDCS) over the human hand motor area

    Microsoft Academic Search

    Toshiaki Furubayashi; Yasuo Terao; Noritoshi Arai; Shingo Okabe; Hitoshi Mochizuki; Ritsuko Hanajima; Masashi Hamada; Akihiro Yugeta; Satomi Inomata-Terada; Yoshikazu Ugawa

    2008-01-01

    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

  6. Cathodal transcranial direct current stimulation of the right Wernicke’s area improves comprehension in subacute stroke patients

    Microsoft Academic Search

    Dae Sang You; Dae-Yul Kim; Min Ho Chun; Seung Eun Jung; Sung Jong Park

    2011-01-01

    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

  7. Diminution of training-induced transient motor cortex plasticity by weak transcranial direct current stimulation in the human

    Microsoft Academic Search

    Karin Rosenkranz; Michael A Nitsche; Frithjof Tergau; Walter Paulus

    2000-01-01

    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

  8. EMG discharge patterns during human grip movement are task-dependent and not modulated by muscle contraction modes: a transcranial magnetic stimulation (TMS) study

    Microsoft Academic Search

    J. G. Anson; Y. Hasegawa; T Kasai; M. L. Latash; S. Yahagi

    2002-01-01

    Our previous study revealed that, during tonic muscle contraction, remarkable functional differences among intrinsic and extrinsic muscles were observed during two different grip movements, i.e., precision and power grips. To verify whether this evidence is true even under the phasic muscle contraction, magnetic stimulation was delivered over the left scalp while a normal human subject performed phasic precision or power

  9. Synthesis of brightly PEGylated luminescent magnetic upconversion nanophosphors for deep tissue and dual MRI imaging.

    PubMed

    Chen, Hongyu; Qi, Bin; Moore, Thomas; Colvin, Daniel C; Crawford, Thomas; Gore, John C; Alexis, Frank; Mefford, O Thompson; Anker, Jeffrey N

    2014-01-15

    A method is developed to fabricate monodispersed biocompatible Yb/Er or Yb/Tm doped ?-NaGdF4 upconversion phosphors using polyelectrolytes to prevent irreversible particle aggregation during conversion of the precursor, Gd2 O(CO3 )2.H2 O: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 Fe3 O4 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. The 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 are studied. 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 tissue. PMID:23828629

  10. Analysis of vector magnetic anomalies over the Bayonnaise Knoll caldera obtained from a deep-sea magnetic exploration by AUV

    NASA Astrophysics Data System (ADS)

    Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.

    2011-12-01

    Geophysical surveys near the seafloor are very effective methods in order to investigate fine structures of the oceanic crust. Such surveys have increased in researches and developments of the seafloor, and will be more and more necessary in the future. For example, seabed resources like hydrothermal deposits have recently focused attention behind the international situation for natural resources like a competition of resources development. In order to estimate accurate abundance of those resources, the above detailed investigations should be needed because of low resolution of geophysical surveys on the sea and low efficiency of exploratory drilling. From such a viewpoint, we have been developing a measurement system for magnetic explorations using an AUV and a deep-tow system. The magnetic exploration system consists of two 3-axis flux-gate magnetometers, one/two Overhauser magnetometer(s), 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 system can measure three components and total intensity of the geomagnetic field in the deep sea. In 2009, the first test of the magnetic exploration 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 magnetic exploration system was further 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 total intensity of magnetic anomalies at altitudes of 60-100 m around the Hakurei deposit and at depth of 500 m above the caldera. The analysis of these data is now energetically pushed forward. A 3D gridded data set of the vector magnetic anomaly in the latter cruise was made by solving the Laplace's equation in the areas where observation data were not available, which is the unique procedure for analysis of the vector anomalies. Several magnetization solutions have been so far obtained by successive approximation and inversion methods. We will here present the measurement of the geomagnetic field and analysis of magnetization structure in Bayonnaise Knoll caldera. Note that this study has been supported by the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

  11. Migraine-Mimicking Headache and Sickle Cell DiseaseA Transcranial Doppler Study

    Microsoft Academic Search

    GS Silva; P Vicari; HC Junior; MH Idagawa; AR Massaro

    2006-01-01

    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%)

  12. Treatment of depression with transcranial direct current stimulation (tDCS): A Review

    Microsoft Academic Search

    Michael A. Nitsche; Paulo S. Boggio; Felipe Fregni; Alvaro Pascual-Leone

    2009-01-01

    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

  13. Transcranial direct current stimulation: A computer-based human model study

    Microsoft Academic Search

    Tim Wagner; Felipe Fregni; Shirley Fecteau; Alan Grodzinsky; Markus Zahn; Alvaro Pascual-Leone

    2007-01-01

    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.

  14. Development of marine magnetic vector measurement system using AUV and deep-towed vehicle

    NASA Astrophysics Data System (ADS)

    Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.; Nishimura, K.; Baba, H.

    2012-04-01

    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).

  15. Deep Gray Matter Demyelination Detected by Magnetization Transfer Ratio in the Cuprizone Model

    PubMed Central

    Fjær, Sveinung; Bø, Lars; Lundervold, Arvid; Myhr, Kjell-Morten; Pavlin, Tina; Torkildsen, Øivind; Wergeland, Stig

    2013-01-01

    In multiple sclerosis (MS), the correlation between lesion load on conventional magnetic resonance imaging (MRI) and clinical disability is weak. This clinico-radiological paradox might partly be due to the low sensitivity of conventional MRI to detect gray matter demyelination. Magnetization transfer ratio (MTR) has previously been shown to detect white matter demyelination in mice. In this study, we investigated whether MTR can detect gray matter demyelination in cuprizone exposed mice. A total of 54 female C57BL/6 mice were split into one control group () and eight cuprizone exposed groups (). The mice were exposed to (w/w) cuprizone for up to six weeks. MTR images were obtained at a 7 Tesla Bruker MR-scanner before cuprizone exposure, weekly for six weeks during cuprizone exposure, and once two weeks after termination of cuprizone exposure. Immunohistochemistry staining for myelin (anti-Proteolopid Protein) and oligodendrocytes (anti-Neurite Outgrowth Inhibitor Protein A) was obtained after each weekly scanning. Rates of MTR change and correlations between MTR values and histological findings were calculated in five brain regions. In the corpus callosum and the deep gray matter a significant rate of MTR value decrease was found, per week () and per week () respectively. The MTR values correlated to myelin loss as evaluated by immunohistochemistry (Corpus callosum: . Deep gray matter: ), but did not correlate to oligodendrocyte density. Significant results were not found in the cerebellum, the olfactory bulb or the cerebral cortex. This study shows that MTR can be used to detect demyelination in the deep gray matter, which is of particular interest for imaging of patients with MS, as deep gray matter demyelination is common in MS, and is not easily detected on conventional clinical MRI. PMID:24386344

  16. Carbon: A bane for giant magnetoresistance magnetic multilayers David X. Yang, Harsh Deep Chopra, B. Shashishekar, P. J. Chen, and W. F. Egelhoff

    E-print Network

    Chopra, Harsh Deep

    Carbon: A bane for giant magnetoresistance magnetic multilayers David X. Yang, Harsh Deep Chopra, B magnetoresistance ratio with temperature in epitaxial Fe/MgO/Co2MnSn magnetic tunnel junctions J. Appl. Phys. 110://apl.aip.org/about/rights_and_permissions #12;Carbon: A bane for giant magnetoresistance magnetic multilayers David X. Yang, Harsh Deep Chopra

  17. Search for magnetic monopoles with deep underwater Cherenkov detectors at Lake Baikal

    E-print Network

    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

    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.

  18. Search for Magnetic Monopoles with Deep Underwater Cherenkov Detectors at Lake Baikal

    E-print Network

    The BAIKAL Collaboration

    1996-01-30

    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.

  19. Rock magnetic signatures in diagenetically altered sediments from the Niger deep-sea fan

    NASA Astrophysics Data System (ADS)

    Dillon, Melanie; Bleil, Ulrich

    2006-03-01

    Diagenesis has extensively affected the magnetic mineral inventory of organic-rich late Quaternary sediments in the Niger deep-sea fan. Changes in concentration, grain size, and coercivity document modifications of the primary magnetic mineral assemblages at two horizons. The first front, the modern iron redox boundary, is characterized by a drastic decline in magnetic mineral content, coarsening of the grain size spectrum, and reduction in coercivity. Beneath a second front, the transition from the suboxic to the sulfidic anoxic domain, a further but less pronounced decrease in concentration and bulk grain size occurs. Finer grains and higher coercive magnetic constituents substantially increase in the anoxic environment. Low- and high-temperature experiments were performed on bulk sediments and on extracts which have also been examined by X-ray diffraction. Thermomagnetic analyses proved ferrimagnetic titanomagnetites of terrigenous provenance as the principal primary magnetic mineral components. Their broad range of titanium contents reflects the volcanogenic traits of the Niger River drainage areas. Diagenetic alteration is not only a grain size selective process but also critically depends on titanomagnetite composition. Low-titanium compounds are less resistant to diagenetic dissolution. Intermediate titanium content titanomagnetite thus persists as the predominant magnetic mineral fraction in the sulfidic anoxic sediments. At the Fe redox boundary, precipitation of authigenic, possibly bacterial, magnetite is documented. The presence of hydrogen sulfide in the pore water suggests a formation of secondary magnetic iron sulfides in the anoxic domain. Grain size-specific data argue for a gradual development of a superparamagnetic and single-domain iron sulfide phase in this milieu, most likely greigite.

  20. Recovery of iron from copper slag by deep reduction and magnetic beneficiation

    NASA Astrophysics Data System (ADS)

    Li, Ke-qing; Ping, Shuo; Wang, Hong-yu; Ni, Wen

    2013-11-01

    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.

  1. Design and testing of planar magnetic micromotors fabricated by deep x-ray lithography and electroplating

    SciTech Connect

    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

    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.

  2. Correlation of transcranial Doppler ultrasonography with MRI and MRA in the evaluation of sickle cell disease patients with prior stroke

    Microsoft Academic Search

    M. S. Kogutt; S. S. Goldwag; K. L. Gupta; K. Kaneko; J. R. Humbert

    1994-01-01

    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

  3. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    PubMed Central

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-01-01

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions. PMID:26045401

  4. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna.

    PubMed

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H; Pagliano, Francesco; Fiore, Andrea; Schuck, P James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-01-01

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the "campanile tip", a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions. PMID:26045401

  5. Exploring the Deep Convection and Magnetism of A-type stars

    NASA Astrophysics Data System (ADS)

    Featherstone, Nicholas; Browning, Matthew; Brun, Allan Sacha; Toomre, Juri

    2011-11-01

    A-type stars have both a near-surface layer of fast convection that can excite acoustic modes and a deep zone of core convection whose properties may be probed with asteroseismology. Many A-type stars also exhibit large magnetic spots that are often attributed to surviving primordial fields of global scale in the intervening radiative zone. We have explored the potential for core convection in rotating A-type stars to build strong magnetic fields through dynamo action. Using the ASH code, we model the inner 30% by radius of a two solar mass A-type star, rotating at four times the solar rate and capturing the convective core and a portion of the overlying radiative envelope. Convection in these stars drives a strong retrograde differential rotation and yields a core that is prolate in shape. When dynamo action is admitted, the convection generates strong magnetic fields largely in equipartition with the dynamics. Remarkably, introducing a modest but large-scale external field threading the radiative envelope (which may be of primordial origin) can substantially alter the turbulent dynamics of the convective interior. The resulting convection establishes a complex assembly of helical rolls that link distant portions of the core and yield magnetic fields of super-equipartition strength.

  6. Exploring the Deep Convection and Magnetism of A-type stars

    NASA Astrophysics Data System (ADS)

    Featherstone, Nicholas; Browning, Matthew; Brun, Allan; Toomre, Juri

    2011-10-01

    A-type stars have both a near-surface layer of fast convection that can excite acoustic modes and a deep zone of core convection whose properties may be probed with asteroseismology. Many A-type stars also exhibit large magnetic spots that are often attributed to surviving primordial fields of global scale in the intervening radiative zone. We have explored the potential for core convection in rotating A-type stars to build strong magnetic fields through dynamo action. Using the ASH code, we model the inner 30% by radius of a two solar mass A-type star, rotating at four times the solar rate and capturing the convective core and a portion of the overlying radiative envelope. Convection in these stars drives a strong retrograde differential rotation and yields a core that is prolate in shape. When dynamo action is admitted, the convection generates strong magnetic fields largely in equipartition with the dynamics. Remarkably, introducing a modest but large-scale external field threading the radiative envelope (which may be of primordial origin) can substantially alter the turbulent dynamics of the convective interior. The resulting convection establishes a complex assembly of helical rolls that link distant portions of the core and yield magnetic fields of super-equipartition strength.

  7. Holocene Variations in the Strength of the North Atlantic Deep Water, a Magnetic Approach

    NASA Astrophysics Data System (ADS)

    Kissel, C.; Laj, C.; Richter, T.; Flesche-Kleiven, H.; Turon, J.; Duprat, J.; Cortijo, E.

    2004-12-01

    Precise documentation of the evolution of the thermohaline circulation (THC) during the Holocene period is raising an increasing interest among the community. Model studies suggest that the strength of the deep water current in North Atlantic is tightly linked to the formation rate of deep-water via the meridional transport of ocean heat. The understanding of the natural variability of the THC during the entire Holocene in North Atlantic is therefore of critical interest for the understanding of its future evolution under the effect of global greenhouse-gas warming. We report on detailed magnetic analyses of 9 Holocene marine sequences distributed from northern to southern Gardar and Bjorn drifts (south of Iceland, 53°N to 61°N), the Gibbs fracture zone (52°S) and from the Eirik drift (south of Greenland). The average sedimentation rate of these sequences varies between 20 and 80 cm/kyr. The cores have been taken on board the R.V. Marion Dufresne of the IPEV during the IMAGES P.I.C.A.S.S.O cruise in June 2003 except for one taken in 1977 with the R.V. J. Charcot. The magnetic parameters indicate that during the Holocene, the magnetic fraction is composed of magnetite with uniform mineralogy and grain size distribution in the pseudo-single domain range (a few micrometers). On the other hand, the concentration varies in space and in time on both long and short terms. In space, the amount of magnetite decreases, together with the magnetic grain size from North to South along the Gardar and Bjorn drifts illustrating a progressive deposition of the magnetic fraction derived from the basaltic Iceland-Faeroe province along the path of the Iceland-Scotland overflow water branch of the NADW. In time, a long-term decrease is observed in the amount of magnetites transported to the studied sites from the northern basaltic province of Iceland and the Faeroe islands. This decrease is not quantitatively compensated by the increase in the carbonate fraction. We interpret this decrease as being directly related to a decrease in the strength of the bottom current through Holocene. The short term features will be discussed for the sequences dated by 14C and compared to other records.

  8. Proton magnetic resonance spectroscopy in deep human brain structures at 7 T

    NASA Astrophysics Data System (ADS)

    Elywa, M.; Mulla-Osman, S.; Godenschweger, F.; Speck, O.

    2012-03-01

    The increased magnetization and frequency separation at high magnetic field strength, such as 7 T, can provide spectra of high signal-to-noise ratio and spectral resolution. However, most human brain magnetic resonance spectroscopy (MRS) studies at 7 T have employed surface coils and thus limited to superficial brain structures. In this study, volume coil excitation together with volume array reception has been utilized to access deeper brain areas. RF power limitations have been addressed by the use of VERSE-modified pulses, and spectra in parietal and pregenual anterior cingulate cortex (pgACC) have been acquired in eight subjects using STEAM with a short echo time of 20 ms. Spectra were analyzed using LC-model. Therefore, an experimental basis set of in vitro spectra was established from 20 human brain metabolite solutions. An exemplary comparison with an optimized PRESS-based single voxel MRS method at 3 T has been performed. Despite the intrinsically lower signal in STEAM, the 7 T spectra show 1.87 times higher signal-to-noise ratio than at 3 T (using PRESS) and more metabolites could be quantified reliably. The results show that the proposed method can be employed at 7 T in deep brain structures and allows the absolute and relative concentrations of human brain metabolites to be determined with low error levels.

  9. Large-scale current systems and ground magnetic disturbance during deep substorm injections

    NASA Astrophysics Data System (ADS)

    Yang, J.; Toffoletto, F. R.; Wolf, R. A.; Sazykin, S.; Ontiveros, P. A.; Weygand, J. M.

    2012-04-01

    We present a detailed analysis of the large-scale current systems and their effects on the ground magnetic field disturbance for an idealized substorm event simulated with the equilibrium version of the Rice Convection Model. The objective of this study is to evaluate how well the bubble-injection picture can account for some classic features of the substorm expansion phase. The entropy depletion inside the bubble is intentionally designed to be so severe that it can penetrate deep into geosynchronous orbit. The results are summarized as follows: (1) Both the region-1-sense and region-2-sense field-aligned currents (FACs) intensify substantially. The former resembles the substorm current wedge and flows along the eastern and western edges of the bubble. The latter is connected to the enhanced partial ring current in the magnetosphere associated with a dipolarization front earthward of the bubble. In the ionosphere, these two pairs of FACs are mostly interconnected via Pedersen currents. (2) The horizontal ionospheric currents show a significant westward electrojet peaked at the equatorward edge of the footprint of the bubble. The estimated ground magnetic disturbance is consistent with the typical features at various locations relative to the center of the westward electrojet. (3) A prominent Harang-reversal-like boundary is seen in both ground ?H disturbance and plasma flow pattern, appearing in the westward portion of the equatorward edge of the bubble footprint, with a latitudinal extent of ˜5° and a longitudinal extent of the half width of the bubble. (4) The dramatic dipolarization inside the bubble causes the ionospheric map of the inner plasma sheet to exhibit a bulge-like structure, which may be related to auroral poleward expansion. (5) The remarkable appearance of the westward electrojet, Harang-reversal-like boundary and poleward expansion starts when the bubble reaches the magnetic transition region from tail-like to dipole-like configuration. We also estimate the horizontal and vertical currents using magnetograms at tens of ground stations for a deep injection substorm event occurred on April 9, 2008, resulting in a picture that is qualitatively consistent with the simulation. Based on the simulations and the observations, an overall picture of the ionospheric dynamics and its magnetospheric drivers during deep bubble injections is obtained.

  10. Scaling behaviour of vertical magnetic susceptibility and its fractal characterization: an example from the German Continental Deep Drilling Project (KTB)

    Microsoft Academic Search

    S. Leonardi; H.-J. Kümpel

    1996-01-01

    The variations of rock magnetism reflect the geological inhomogeneities of the earth's crust, i.e. its petrological-mineralogical and structural organization. The present state of the crust bears meaningful information of its past dynamic processes and evolution. We analysed magnetic susceptibility data series from the boreholes of the German Continental Deep Drilling Project (KTB). By means of spectral and rescaled-range (R\\/S) analyses

  11. Magnetic field dipolarization in the deep inner magnetosphere and its role in development of O+-rich ring current

    Microsoft Academic Search

    M. Nosé; H. Koshiishi; H. Matsumoto; K. Keika; K. Koga; T. Goka; T. Obara

    2010-01-01

    We studied magnetic field dipolarization and associated ion acceleration in the deep inner magnetosphere, using magnetic field data obtained by the magnetometer on board the Mission Demonstration Satellite 1 (MDS-1) and the energetic neutral atom (ENA) flux data obtained by the high-energy neutral analyzer imager on board the Imager for Magnetopause-to-Aurora Global Exploration satellite. Because the MDS-1 satellite has a

  12. Transcranial direct current stimulation: before, during, or after motor training?

    PubMed

    Cabral, Maria E; Baltar, Adriana; Borba, Rebeka; Galvão, Silvana; Santos, Luciana; Fregni, Felipe; Monte-Silva, Kátia

    2015-08-01

    Noninvasive brain stimulation has recently been used to augment motor training-induced plasticity. However, the exact time during which noninvasive brain stimulation can be combined with motor therapy to maximize neuroplasticity and behavioral changes is unknown. We conducted a randomized sham-controlled crossover trial to examine when (before, during, or after training) transcranial direct current stimulation (tDCS) should be applied to best reinforce motor training-induced plasticity in 12 healthy right-handed participants (mean age: 21.8±1.6) who underwent active or sham tDCS combined with motor training. Transcranial magnetic stimulation-elicited motor-evoked potentials from the right first dorsal interosseous muscle were recorded before (baseline) and immediately after each session. The training task comprised four practice trials - 3?min each (30?s pause between trials) - of repetitive finger movements (thumb abduction/adduction) with the right hand. Anodal tDCS (1?mA, 13?min, on the motor primary cortex) was applied before, during, and after the training. Compared with baseline motor-evoked potentials and the sham condition, tDCS that was applied before, but not during or after, the motor task enhanced corticospinal excitability. These data suggest that tDCS performed before - not during or after - promotes optimization of motor training-induced plasticity. PMID:26049257

  13. Toroidal magnetic fields for protecting astronauts from ionizing radiation in long duration deep space missions

    NASA Astrophysics Data System (ADS)

    Papini, Paolo; Spillantini, Piero

    2014-11-01

    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.

  14. Transcranial direct current stimulation for major depression: A general system for quantifying transcranial electrotherapy dosage

    Microsoft Academic Search

    Marom Bikson; Peter Bulow; John W. Stiller; Abhishek Datta; Fortunato Battaglia; Sergei V. Karnup; Teodor T. Postolache

    2008-01-01

    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

  15. Modulation of moving phosphene thresholds by transcranial direct current stimulation of V1 in human

    Microsoft Academic Search

    Andrea Antal; Tamás Z. Kincses; Michael A. Nitsche; Walter Paulus

    2003-01-01

    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

  16. Magnetic resonance image analysis of meniscal translation and tibio-menisco-femoral contact in deep knee flexion.

    PubMed

    Yao, Jiang; Lancianese, Sarah L; Hovinga, Kristen R; Lee, Jordan; Lerner, Amy L

    2008-05-01

    The purpose of this study was to clarify meniscal displacement and cartilage-meniscus contact behavior in a full extension position and a deep knee flexion position. We also studied whether the meniscal translation pattern correlated with the tibiofemoral cartilage contact kinematics. Magnetic resonance (MR) images were acquired at both positions for 10 subjects using a conventional MR scanner. Subjects achieved a flexion angle averaging 139 degrees +/- 3 degrees. Both medial and lateral menisci translated posteriorly on the tibial plateau during deep knee flexion. The posterior translation of the lateral meniscus (8.2 +/- 3.2 mm) was greater than the medial (3.3 +/- 1.5 mm). This difference was correlated with the difference in tibiofemoral contact kinematics between medial and lateral compartments. Contact areas in deep flexion were approximately 75% those at full extension. In addition, the percentage of area in contact with menisci increased significantly due to deep flexion. Our results related to meniscal translation and tibio-menisco-femoral contact in deep knee flexion, in combination with information about force and pressure in the knee, may lead to a better understanding of the mechanism of meniscal degeneration and osteoarthritis associated with prolonged kneeling and squatting. PMID:18183628

  17. Combining TMS-EEG with transcranial direct current stimulation language treatment in aphasia.

    PubMed

    Cipollari, Susanna; Veniero, Domenica; Razzano, Carmela; Caltagirone, Carlo; Koch, Giacomo; Marangolo, Paola

    2015-07-01

    Despite the fact that different studies have been performed using transcranial direct current stimulation (tDCS) in aphasia, so far, to what extent the stimulation of a cerebral region may affect the activity of anatomically connected regions remains unclear. The authors used a combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to explore brain areas' excitability modulation before and after active and sham tDCS. Six chronic aphasics underwent 3 weeks of language training coupled with tDCS over the right inferior frontal gyrus. To measure the changes induced by tDCS, TMS-EEG closed to the area stimulated with tDCS were calculated. A significant improvement after tDCS stimulation was found which was accompained by a modification of the EEG over the stimulated region. PMID:26109229

  18. Trans-cranial focused ultrasound without hair shaving: feasibility study in an ex vivo cadaver model

    PubMed Central

    2013-01-01

    In preparing a patient for a trans-cranial magnetic resonance (MR)-guided focused ultrasound procedure, current practice is to shave the patient’s head on treatment day. Here we present an initial attempt to evaluate the feasibility of trans-cranial focused ultrasound in an unshaved, ex vivo human head model. A human skull filled with tissue-mimicking phantom and covered with a wig made of human hair was sonicated using 220- and 710-kHz head transducers to evaluate the feasibility of acoustic energy transfer. Heating at the focal point was measured by MR proton resonance shift thermometry. Results showed that the hair had a negligible effect on focal spot thermal rise at 220 kHz and a 17% drop in temperature elevation when using 710 kHz. PMID:25512865

  19. Transcranial Electrical Stimulation Accelerates Human Sleep Homeostasis

    PubMed Central

    Reato, Davide; Gasca, Fernando; Datta, Abhishek; Bikson, Marom; Marshall, Lisa; Parra, Lucas C.

    2013-01-01

    The sleeping brain exhibits characteristic slow-wave activity which decays over the course of the night. This decay is thought to result from homeostatic synaptic downscaling. Transcranial electrical stimulation can entrain slow-wave oscillations (SWO) in the human electro-encephalogram (EEG). A computational model of the underlying mechanism predicts that firing rates are predominantly increased during stimulation. Assuming that synaptic homeostasis is driven by average firing rates, we expected an acceleration of synaptic downscaling during stimulation, which is compensated by a reduced drive after stimulation. We show that 25 minutes of transcranial electrical stimulation, as predicted, reduced the decay of SWO in the remainder of the night. Anatomically accurate simulations of the field intensities on human cortex precisely matched the effect size in different EEG electrodes. Together these results suggest a mechanistic link between electrical stimulation and accelerated synaptic homeostasis in human sleep. PMID:23459152

  20. Brain embolism monitoring with transcranial Doppler ultrasound

    Microsoft Academic Search

    Viken L. Babikian; Christine A. Wijman

    2003-01-01

    Opinion statement  Embolism is considered to be the main mechanism leading to brain infarction today; with the introduction of sophisticated\\u000a neuroimaging tools, its impact is increasingly appreciated. Transcranial Doppler ultrasound allows noninvasive monitoring\\u000a of in vivo embolism. Acute stroke, internal carotid artery stenosis, several cardiac conditions, internal carotid endarterectomy,\\u000a and coronary artery bypass graft surgery have been extensively monitored. These investigations

  1. Absolute magnetization of the seafloor at a basalt-hosted hydrothermal site: Insights from a deep-sea submersible survey

    NASA Astrophysics Data System (ADS)

    Szitkar, Florent; Dyment, Jérôme; Fouquet, Yves; Choi, Yujin; Honsho, Chie

    2015-02-01

    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.

  2. 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

  3. Monsoon variability and deep oceanic circulation in the western equatorial Pacific over the last climatic cycle: Insights from sedimentary magnetic properties and sortable silt

    Microsoft Academic Search

    Catherine Kissel; Carlo Laj; Markus Kienast; Timothé Bolliet; Ann Holbourn; Paul Hill; Wolfgang Kuhnt; Pascale Braconnot

    2010-01-01

    Magnetic and grain size properties of a sediment core located in the western equatorial Pacific, off the southeastern tip of the Philippine island of Mindanao, are presented in an effort to reconstruct past changes in the East Asian Monsoon and deep ocean circulation during the last 160 kyrs. The sedimentary concentration of magnetic particles, interpreted to reflect past changes in

  4. Electronic and magnetic structures of the postperovskite-type Fe{sub 2}O{sub 3} and implications for planetary magnetic records and deep interiors.

    SciTech Connect

    Shim, S.H.; Bengtson, A.; Morgan, D.; Sturhahn, W.; Catalli, K.; Zhao, J.; Lerche, M.; Prakapenka, V.; X-Ray Science Division; Massachusetts Inst. of Tech.; Univ. of Wisconsin; Carnegie Institution of Washington; Univ. of Chicago

    2009-04-07

    Recent studies have shown that high pressure (P) induces the metallization of the Fe{sup 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{sub 2}O{sub 3}) is an important magnetic carrier mineral for deciphering planetary magnetism and a proxy for Fe in the planetary interiors. Here, we present synchrotron Moessbauer spectroscopy and X-ray diffraction combined with ab initio calculations for Fe{sub 2}O{sub 3} revealing the destruction of magnetic ordering at the hematite {yields} Rh{sub 2}O{sub 3}-II type (RhII) transition at 70 GPa and 300 K, and then the revival of magnetic ordering at the RhII {yields} postperovskite (PPv) transition after laser heating at 73 GPa. At the latter transition, at least half of Fe{sup 3+} ions transform from LS to HS and Fe{sub 2}O{sub 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.

  5. Upper Miocene to Recent Magnetic Stratigraphy in Deep-Sea Sediments

    Microsoft Academic Search

    John H. Foster; Neil D. Opdyke

    1970-01-01

    Two of the longest piston cores of deep-sea sediment ever recovered were taken in the equatorial Pacific on the twelfth cruise of the research vessel Robert D. Conrad. The two cores, 26 and 28 meters in length, penetrate calcareous and siliceous ooze to sediments of Miocene age. Paleomagnetic measurements were made on samples partially demagnetized in a 60-Hz alternating field

  6. Transcranial Cavitation Detection in Primates during Blood-Brain Barrier Opening – A Performance Assessment Study

    PubMed Central

    Wu, Shih-Ying; Tung, Yao-Sheng; Marquet, Fabrice; Downs, Matthew Eric; Sanchez, Carlos Sierra; Chen, Cherry Chen; Ferrera, Vincent

    2014-01-01

    Focused ultrasound (FUS) has been shown promise in treating the brain locally and noninvasively. Transcranial passive cavitation detection (PCD) provides methodology of monitoring the treatment in real time, while the skull effects remain a major challenge for its translation to the clinic. In this study, we investigated the sensitivity, reliability, and limitations of PCD through primate (macaque and human) skulls in vitro. The results were further correlated with the in vivo macaque studies including the transcranial PCD calibration and real-time monitoring of BBB opening, with magnetic resonance imaging assessing the opening and safety. The stable cavitation doses using harmonics (SCDh) and ultraharmonics (SCDu), the inertial cavitation dose (ICD), and the cavitation signal-to-noise ratio (SNR) were quantified based on the PCD signals. Results showed that through the macaque skull the pressure threshold for detecting the SCDh remained the same as without the skull in place, while it increased for the SCDu and ICD; through the human skull, it increased for all cavitation doses. The transcranial PCD was found reliable both in vitro and in vivo when the transcranial cavitation SNR exceeded the 1-dB detection limit through the in vitro macaque (attenuation: 4.92 dB/mm) and human (attenuation: 7.33 dB/mm) skull. In addition, using long pulses enabled reliable PCD monitoring and facilitate BBB opening at low pressures. The in vivo results showed that the SCDh became detectable at pressures as low as 100 kPa; the ICD, at 250 kPa while it could occur at lower pressures; the SCDu, at 700 kPa and was less reliable at lower pressures. Real-time monitoring of PCD was further implemented during BBB opening, with successful and safe opening achieved at 250–600 kPa in both the thalamus and the putamen. In conclusion, this study shows that transcranial PCD in macaques in vitro and in vivo as well as humans in vitro is reliable by improving the cavitation SNR beyond the 1-dB detection limit. PMID:24859660

  7. Individual differences in transcranial electrical stimulation current density

    PubMed Central

    Russell, Michael J; Goodman, Theodore; Pierson, Ronald; Shepherd, Shane; Wang, Qiang; Groshong, Bennett; Wiley, David F

    2013-01-01

    Transcranial electrical stimulation (TCES) is effective in treating many conditions, but it has not been possible to accurately forecast current density within the complex anatomy of a given subject's head. We sought to predict and verify TCES current densities and determine the variability of these current distributions in patient-specific models based on magnetic resonance imaging (MRI) data. Two experiments were performed. The first experiment estimated conductivity from MRIs and compared the current density results against actual measurements from the scalp surface of 3 subjects. In the second experiment, virtual electrodes were placed on the scalps of 18 subjects to model simulated current densities with 2 mA of virtually applied stimulation. This procedure was repeated for 4 electrode locations. Current densities were then calculated for 75 brain regions. Comparison of modeled and measured external current in experiment 1 yielded a correlation of r = .93. In experiment 2, modeled individual differences were greatest near the electrodes (ten-fold differences were common), but simulated current was found in all regions of the brain. Sites that were distant from the electrodes (e.g. hypothalamus) typically showed two-fold individual differences. MRI-based modeling can effectively predict current densities in individual brains. Significant variation occurs between subjects with the same applied electrode configuration. Individualized MRI-based modeling should be considered in place of the 10-20 system when accurate TCES is needed. PMID:24285948

  8. An electronically steered, wearable transcranial doppler ultrasound system

    E-print Network

    Pietrangelo, Sabino Joseph

    2013-01-01

    This thesis details the design of a transcranial Doppler (TCD) ultrasound system to measure cerebral blood flow velocity (CBFV) at the middle cerebral artery (MCA). TCD sonography has been clinically indicated in a variety ...

  9. Standing-Wave Suppression for Transcranial Ultrasound by Random Modulation

    Microsoft Academic Search

    Gregory T. Clement

    2010-01-01

    Low-frequency transcranial ultrasound (??1 MHz) is being investigated for a number of brain therapies, including stroke, tumor ablation, and localized opening of the blood-brain barrier. However, lower frequencies have been associated with the production of undesired standing waves and cavitation in the brain. Presently, we examine an approach to suppress standing waves during continuous-wave (CW) transcranial application. The investigation uses

  10. Do low field magnetic resonance imaging abnormalities correlate with macroscopical and histological changes within the equine deep digital flexor tendon?

    PubMed

    Sherlock, C E; Mair, T S; Ireland, J; Blunden, T

    2015-02-01

    Correlating magnetic resonance (MR) imaging and histopathological findings is essential to validate low field MR imaging in lame horses. This study aimed to compare signal changes in the deep digital flexor tendon (DDFT) of the distal limb on low field MR imaging with macroscopical and histological findings. Cadaver limbs from lame horses with DDFT lesions were selected. The DDFT MR imaging findings and histopathological results were graded, and macroscopical abnormalities were recorded. There was a strong correlation between MR imaging and histopathology grades (rs?=?0.76, p?

  11. Deep-tow study of magnetic anomalies in the Pacific Jurassic Quiet Zone 

    E-print Network

    Tominaga, Masako

    2006-10-30

    and correlatability of the JQZ magnetic anomalies implying that they are seafloor spreading lineations and (2) good correlations made new GPTS models extending back to 169.4 Ma; and (3) the origin of the JQZ may be a combination of rapid polarity reversals...

  12. CHILES Con Pol: Probing galaxy evolution, the dark Universe, and cosmic magnetism with a deep 1000 hour Jansky VLA survey

    NASA Astrophysics Data System (ADS)

    Hales, Christopher A.; Chiles Con Pol Collaboration

    2014-04-01

    We recently started a 1000 hour campaign to observe 0.2 square degrees of the COSMOS field in full polarization continuum at 1.4 GHz with the Jansky VLA, as part of a joint program with the spectral line COSMOS HI Large Extragalactic Survey (CHILES). When complete, we expect our CHILES Continuum Polarization (CHILES Con Pol) survey to reach an unprecedented SKA-era sensitivity of 0.7 uJy per 4 arcsecond FWHM beam. Here we present the key goals of CHILES Con Pol, which are to (i) produce a source catalog of legacy value to the astronomical community, (ii) measure differential source counts in total intensity, linear polarization, and circular polarization in order to constrain the redshift and luminosity distributions of source populations, (iii) perform a novel weak lensing study using radio polarization as an indicator of intrinsic alignment to better study dark energy and dark matter, and (iv) probe the unknown origin of cosmic magnetism by measuring the strength and structure of intergalactic magnetic fields in the filaments of large scale structure. The CHILES Con Pol source catalog will be a useful resource for upcoming wide-field surveys by acting as a training set for machine learning algorithms, which can then be used to identify and classify radio sources in regions lacking deep multiwavelength coverage.

  13. Magnetic graphene oxide modified with choline chloride-based deep eutectic solvent for the solid-phase extraction of protein.

    PubMed

    Huang, Yanhua; Wang, Yuzhi; Pan, Qi; Wang, Ying; Ding, Xueqin; Xu, Kaijia; Li, Na; Wen, Qian

    2015-06-01

    Four kinds of green deep eutectic solvents (DESs) based on choline chloride (ChCl) have been synthesized and coated on the surface of magnetic graphene oxide (Fe3O4@GO) to form Fe3O4@GO-DES for the magnetic solid-phase extraction of protein. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were employed to characterize Fe3O4@GO-DES, and the results indicated the successful preparation of Fe3O4@GO-DES. The UV-vis spectrophotometer was used to measure the concentration of protein after extraction. Single factor experiments proved that the extraction amount was influenced by the types of DESs, solution temperature, solution ionic strength, extraction time, protein concentration and the amount of Fe3O4@GO-DES. Comparison of Fe3O4@GO and Fe3O4@GO-DES was carried out by extracting bovine serum albumin, ovalbumin, bovine hemoglobin and lysozyme. The experimental results showed that the proposed Fe3O4@GO-DES performs better than Fe3O4@GO in the extraction of acidic protein. Desorption of protein was carried out by eluting the solid extractant with 0.005molL(-1) Na2HPO4 contained 1molL(-1) NaCl. The obtained elution efficiency was about 90.9%. Attributed to the convenient magnetic separation, the solid extractant could be easily recycled. PMID:26002214

  14. Efficacy of repetitive transcranial magnetic stimulation\\/transcranial direct current stimulation in cognitive neurorehabilitation

    Microsoft Academic Search

    Carlo Miniussi; Stefano F. Cappa; Leonardo G. Cohen; Agnes Floel; Felipe Fregni; Michael A. Nitsche; Massimiliano Oliveri; Alvaro Pascual-Leone; Walter Paulus; Alberto Priori; Vincent Walsh

    2008-01-01

    Summary Cognitive deficits are a common consequence of neurologic disease, in particular, of traumatic brain injury, stroke, and neurodegenerative disorders, and there is evidence that specific cognitive training may be effective in cognitive rehabilitation. Several investigations emphasize the fact that interacting with cortical activity, by means of cortical stimulation, can positively affect the short-term cognitive performance and improve the rehabilitation

  15. An Intraoperative Brain-shift Monitor Using Shear-mode Transcranial Ultrasound: Preliminary Results

    PubMed Central

    White, P. Jason; Whalen, Stephen; Tang, Sai Chun; Clement, Greg T.; Golby, Alexandra J.

    2008-01-01

    Objective Various methods of intraoperative structural monitoring during neurosurgery are used to localize lesions after brain shift and guiding surgically introduced probes such as biopsy needles or stimulation electrodes. With its high temporal resolution, portability, and non-ionizing mode of radiation, ultrasound has potential advantages over other existing imaging modalities for intraoperative monitoring. Yet, sonography is rarely used during neurosurgery largely because of the craniotomy requirement to achieve sufficiently useful signals. Methods Prompted by results from recent studies on transcranial ultrasound, a prototype device that aims to use the shear mode of transcranial ultrasound transmission for intraoperative monitoring has been designed, constructed, and tested with 10 human subjects. Magnetic resonance (MR) images were then obtained with the device spatially registered to the MR reference coordinates. Peaks in both the ultrasound and MR signals were identified and analyzed both for spatial localization and signal-to-noise ratio (SNR). Results The first results aimed towards validating the prototype device with MRI have demonstrated excellent correlation (n = 38, R2 = 0.9962) between the structural localization abilities of the two modalities. In addition, the overall SNR of the ultrasound backscatter signals (n = 38, SNR = 25.4±5.2 dB) was statistically equivalent to that of the MR data (n = 38, SNR = 22.5±4.8 dB). Conclusions A statistically significant correlation of localized intracranial structures between ITUM and MRI data has been achieved with 10 human subjects. This is the first demonstration and validation of a prototype device incorporating transcranial shear-mode ultrasound towards a clinical monitoring application. PMID:19168769

  16. The Point Spread Function of the Human Head and its Implications for Transcranial Current

    E-print Network

    Parra, Lucas C.

    The Point Spread Function of the Human Head and its Implications for Transcranial Current of transcranial current stimulation (tCS) requires solving the "forward problem": to compute the electric field for targeting an infinitesimal point in the brain are shown. #12;2 1. Introduction Transcranial current

  17. Transcranial electrical stimulation affects adaptation of MT/V5 neurons in awake, behaving macaques

    E-print Network

    Krekelberg, Bart

    directions). In the stimulation conditions we applied transcranial alternating current stimulation (tACS; 10Transcranial electrical stimulation affects adaptation of MT/V5 neurons in awake, behaving macaques of action of transcranial electrical stimulation (tES) are poorly understood. We partially attribute

  18. Nanoscale nuclear magnetic resonance with a 1.9-nm-deep nitrogen-vacancy sensor

    SciTech Connect

    Loretz, M.; Degen, C. L., E-mail: degenc@ethz.ch [Department of Physics, ETH Zurich, Schafmattstrasse 16, 8093 Zurich (Switzerland); Pezzagna, S.; Meijer, J. [Department of Nuclear Solid State Physics, Institute for Experimental Physics II, Universität Leipzig, Linnéstr. 5, D-04103 Leipzig (Germany)

    2014-01-20

    We present nanoscale nuclear magnetic resonance (NMR) measurements performed with nitrogen-vacancy (NV) centers located down to about 2 nm from the diamond surface. NV centers were created by shallow ion implantation followed by a slow, nanometer-by-nanometer removal of diamond material using oxidative etching in air. The close proximity of NV centers to the surface yielded large {sup 1}H NMR signals of up to 3.4 ?T-rms, corresponding to ?330 statistically polarized or ?10 fully polarized proton spins in a (1.8 nm){sup 3} detection volume.

  19. Ambient-Pressure Bulk Superconductivity Deep in the Magnetic State of CeRhIn5

    SciTech Connect

    Paglione,J.; Ho, P.; Maple, M.; Tanatar, M.; Taillefer, L.; Lee, Y.; Petrovic, C.

    2008-01-01

    Specific heat, magnetic susceptibility and electrical transport measurements were performed at ambient pressure on high-quality single crystal specimens of CeRhIn5 down to ultra-low temperatures. We report signatures of an anomaly observed in all measured quantities consistent with a bulk phase transition to a superconducting state at T{sub c}=110 mK. Occurring far below the onset of antiferromagnetism at T{sub N}=3.8 K, this transition appears to involve a significant portion of the available low-temperature density of electronic states, exhibiting an entropy change in line with that found in other members of the 115 family of superconductors tuned away from quantum criticality.

  20. Transcranial random noise stimulation-induced plasticity is NMDA-receptor independent but sodium-channel blocker and benzodiazepines sensitive

    PubMed Central

    Chaieb, Leila; Antal, Andrea; Paulus, Walter

    2015-01-01

    Background: Application of transcranial random noise stimulation (tRNS) between 0.1 and 640 Hz of the primary motor cortex (M1) for 10 min induces a persistent excitability increase lasting for at least 60 min. However, the mechanism of tRNS-induced cortical excitability alterations is not yet fully understood. Objective: The main aim of this study was to get first efficacy data with regard to the possible neuronal effect of tRNS. Methods: Single-pulse transcranial magnetic stimulation (TMS) was used to measure levels of cortical excitability before and after combined application of tRNS at an intensity of 1 mA for 10 min stimulation duration and a pharmacological agent (or sham) on eight healthy male participants. Results: The sodium channel blocker carbamazepine showed a tendency toward inhibiting MEPs 5–60 min poststimulation. The GABAA agonist lorazepam suppressed tRNS-induced cortical excitability increases at 0–20 and 60 min time points. The partial NMDA receptor agonist D-cycloserine, the NMDA receptor antagonist dextromethorphan and the D2/D3 receptor agonist ropinirole had no significant effects on the excitability increases seen with tRNS. Conclusions: In contrast to transcranial direct current stimulation (tDCS), aftereffects of tRNS are seem to be not NMDA receptor dependent and can be suppressed by benzodiazepines suggesting that tDCS and tRNS depend upon different mechanisms. PMID:25914617

  1. Transcranial Direct Current Stimulation in Schizophrenia

    PubMed Central

    Agarwal, Sri Mahavir; Shivakumar, Venkataram; Bose, Anushree; Subramaniam, Aditi; Nawani, Hema; Chhabra, Harleen; Kalmady, Sunil V.; Narayanaswamy, Janardhanan C.

    2013-01-01

    Transcranial direct current stimulation (tDCS) is an upcoming treatment modality for patients with schizophrenia. A series of recent observations have demonstrated improvement in clinical status of schizophrenia patients with tDCS. This review summarizes the research work that has examined the effects of tDCS in schizophrenia patients with respect to symptom amelioration, cognitive enhancement and neuroplasticity evaluation. tDCS is emerging as a safe, rapid and effective treatment for various aspects of schizophrenia symptoms ranging from auditory hallucinations-for which the effect is most marked, to negative symptoms and cognitive symptoms as well. An interesting line of investigation involves using tDCS for altering and examining neuroplasticity in patients and healthy subjects and is likely to lead to new insights into the neurological aberrations and pathophysiology of schizophrenia. The mechanistic aspects of the technique are discussed in brief. Future work should focus on establishing the clinical efficacy of this novel technique and on evaluating this modality as an adjunct to cognitive enhancement protocols. Understanding the mechanism of action of tDCS as well as the determinants and neurobiological correlates of clinical response to tDCS remains an important goal, which will help us expand the clinical applications of tDCS for the treatment of patients with schizophrenia. PMID:24465247

  2. Transcranial direct-current stimulation reduced the excitability of diaphragmatic corticospinal pathways whatever the polarity used.

    PubMed

    Azabou, Eric; Roche, Nicolas; Sharshar, Tarek; Bussel, Bernard; Lofaso, Frédéric; Petitjean, Michel

    2013-10-01

    We investigated effects of transcranial direct-current stimulation (tDCS) on the diaphragmatic corticospinal pathways in healthy human. Anodal, cathodal, and sham tDCS were randomly applied upon the left diaphragmatic motor cortex in twelve healthy right-handed men. Corticospinal pathways excitability was assessed by means of transcranial magnetic stimulation (TMS) elicited motor-evoked-potential (MEP). For each tDCS condition, MEPs were recorded before (Pre) tDCS then after 10 min (Post1, at tDCS discontinuation in the anodal and cathodal sessions) and 20 min (Post2). As result, both anodal and cathodal tDCS significantly decreased MEP amplitude of the right hemidiaphragm at both Post1 and Post2, versus Pre. MEP amplitude was unchanged versus Pre during the sham condition. The effects of cathodal and anodal tDCS applied to the diaphragm motor cortex differ from those observed during tDCS of the limb motor cortex. These differences may be related to specific characteristics of the diaphragmatic corticospinal pathways as well as to the diaphragm's functional peculiarities compared with the limb muscles. PMID:23933029

  3. Transcranial cerebellar direct current stimulation (tcDCS): motor control, cognition, learning and emotions.

    PubMed

    Ferrucci, Roberta; Priori, Alberto

    2014-01-15

    The neurological manifestations of cerebellar diseases range from motor to cognitive or behavioral abnormalities. Experimental data in healthy subjects extend the cerebellar role to learning, emotional and mood control. The need for a non-invasive tool to influence cerebellar function in normal and pathological conditions led researchers to develop transcranial cerebellar direct current stimulation (tcDCS). tcDCS, like tDCS, depends on the principle that weak direct currents delivered at around 2mA for minutes over the cerebellum through surface electrodes induce prolonged changes in cerebellar function. tcDCS modulates several cerebellar skills in humans including motor control, learning and emotional processing. tcDCS also influences the cerebello-brain interactions induced by transcranial magnetic stimulation (TMS), walking adaptation, working memory and emotional recognition. Hence tcDCS is a simple physiological tool that can improve our physiological understanding of the human cerebellum, and should prove useful also in patients with cerebellar dysfunction or psychiatric disorders and those undergoing neurorehabilitation to enhance neuroplasticity. PMID:23664951

  4. Effects of Frontal Transcranial Direct Current Stimulation on Emotional State and Processing in Healthy Humans

    PubMed Central

    Nitsche, M. A.; Koschack, J.; Pohlers, H.; Hullemann, S.; Paulus, W.; Happe, S.

    2012-01-01

    The prefrontal cortex is involved in mood and emotional processing. In patients suffering from depression, the left dorsolateral prefrontal cortex (DLPFC) is hypoactive, while activity of the right DLPFC is enhanced. Counterbalancing these pathological excitability alterations by repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) improves mood in these patients. In healthy subjects, however, rTMS of the same areas has no major effect, and the effects of tDCS are mixed. We aimed to evaluate the effects of prefrontal tDCS on emotion and emotion-related cognitive processing in healthy humans. In a first study, we administered excitability-enhancing anodal, excitability-diminishing cathodal, and placebo tDCS to the left DLPFC, combined with antagonistic stimulation of the right frontopolar cortex, and tested acute emotional changes by an adjective checklist. Subjective emotions were not influenced by tDCS. Emotional face identification, however, which was explored in a second experiment, was subtly improved by a tDCS-driven excitability modulation of the prefrontal cortex, markedly by anodal tDCS of the left DLPFC for positive emotional content. We conclude that tDCS of the prefrontal cortex improves emotion processing in healthy subjects, but does not influence subjective emotional state. PMID:22723786

  5. Effects of frontal transcranial direct current stimulation on emotional state and processing in healthy humans.

    PubMed

    Nitsche, M A; Koschack, J; Pohlers, H; Hullemann, S; Paulus, W; Happe, S

    2012-01-01

    The prefrontal cortex is involved in mood and emotional processing. In patients suffering from depression, the left dorsolateral prefrontal cortex (DLPFC) is hypoactive, while activity of the right DLPFC is enhanced. Counterbalancing these pathological excitability alterations by repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) improves mood in these patients. In healthy subjects, however, rTMS of the same areas has no major effect, and the effects of tDCS are mixed. We aimed to evaluate the effects of prefrontal tDCS on emotion and emotion-related cognitive processing in healthy humans. In a first study, we administered excitability-enhancing anodal, excitability-diminishing cathodal, and placebo tDCS to the left DLPFC, combined with antagonistic stimulation of the right frontopolar cortex, and tested acute emotional changes by an adjective checklist. Subjective emotions were not influenced by tDCS. Emotional face identification, however, which was explored in a second experiment, was subtly improved by a tDCS-driven excitability modulation of the prefrontal cortex, markedly by anodal tDCS of the left DLPFC for positive emotional content. We conclude that tDCS of the prefrontal cortex improves emotion processing in healthy subjects, but does not influence subjective emotional state. PMID:22723786

  6. Transcranial direct current stimulation improves ipsilateral selective muscle activation in a frequency dependent manner.

    PubMed

    Uehara, Kazumasa; Coxon, James P; Byblow, Winston D

    2015-01-01

    Failure to suppress antagonist muscles can lead to movement dysfunction, such as the abnormal muscle synergies often seen in the upper limb after stroke. A neurophysiological surrogate of upper limb synergies, the selectivity ratio (SR), can be determined from the ratio of biceps brachii (BB) motor evoked potentials to transcranial magnetic stimulation prior to forearm pronation versus elbow flexion. Surprisingly, cathodal transcranial direct current stimulation (c-TDCS) over ipsilateral primary motor cortex (M1) reduces (i.e. improves) the SR in healthy adults, and chronic stroke patients. The ability to suppress antagonist muscles may be exacerbated at high movement rates. The aim of the present study was to investigate whether the selective muscle activation of the biceps brachii (BB) is dependent on altering frequency demands, and whether the c-tDCS improvement of SR is dependent on task frequency. Seventeen healthy participants performed repetitive isometric elbow flexion and forearm pronation at three rates, before and after c-tDCS or sham delivered to ipsilateral left M1. Ipsilateral c-tDCS improved the SR in a frequency dependent manner by selectively suppressing BB antagonist excitability. Our findings confirm that c-tDCS is an effective tool for improving selective muscle activation, and provide novel evidence for its efficacy at rates of movement where it is most likely to benefit task performance. PMID:25816204

  7. Different Current Intensities of Anodal Transcranial Direct Current Stimulation Do Not Differentially Modulate Motor Cortex Plasticity

    PubMed Central

    Kidgell, Dawson J.; Daly, Robin M.; Young, Kayleigh; Lum, Jarrod; Tooley, Gregory; Jaberzadeh, Shapour; Zoghi, Maryam; Pearce, Alan J.

    2013-01-01

    Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates the excitability of neurons within the motor cortex (M1). Although the aftereffects of anodal tDCS on modulating cortical excitability have been described, there is limited data describing the outcomes of different tDCS intensities on intracortical circuits. To further elucidate the mechanisms underlying the aftereffects of M1 excitability following anodal tDCS, we used transcranial magnetic stimulation (TMS) to examine the effect of different intensities on cortical excitability and short-interval intracortical inhibition (SICI). Using a randomized, counterbalanced, crossover design, with a one-week wash-out period, 14 participants (6 females and 8 males, 22–45 years) were exposed to 10 minutes of anodal tDCS at 0.8, 1.0, and 1.2?mA. TMS was used to measure M1 excitability and SICI of the contralateral wrist extensor muscle at baseline, immediately after and 15 and 30 minutes following cessation of anodal tDCS. Cortical excitability increased, whilst SICI was reduced at all time points following anodal tDCS. Interestingly, there were no differences between the three intensities of anodal tDCS on modulating cortical excitability or SICI. These results suggest that the aftereffect of anodal tDCS on facilitating cortical excitability is due to the modulation of synaptic mechanisms associated with long-term potentiation and is not influenced by different tDCS intensities. PMID:23577272

  8. Heating induced near deep brain stimulation lead electrodes during magnetic resonance imaging with a 3 T transceive volume head coil

    NASA Astrophysics Data System (ADS)

    Shrivastava, Devashish; Abosch, Aviva; Hughes, John; Goerke, Ute; DelaBarre, Lance; Visaria, Rachana; Harel, Noam; Vaughan, J. Thomas

    2012-09-01

    Heating induced near deep brain stimulation (DBS) lead electrodes during magnetic resonance imaging with a 3 T transceive head coil was measured, modeled, and imaged in three cadaveric porcine heads (mean body weight = 85.47 ± 3.19 kg, mean head weight = 5.78 ± 0.32 kg). The effect of the placement of the extra-cranial portion of the DBS lead on the heating was investigated by looping the extra-cranial lead on the top, side, and back of the head, and placing it parallel to the coil's longitudinal axial direction. The heating was induced using a 641 s long turbo spin echo sequence with the mean whole head average specific absorption rate of 3.16 W kg-1. Temperatures were measured using fluoroptic probes at the scalp, first and second electrodes from the distal lead tip, and 6 mm distal from electrode 1 (T6 mm). The heating was modeled using the maximum T6 mm and imaged using a proton resonance frequency shift-based MR thermometry method. Results showed that the heating was significantly reduced when the extra-cranial lead was placed in the longitudinal direction compared to the other placements (peak temperature change = 1.5-3.2 °C versus 5.1-24.7 °C). Thermal modeling and MR thermometry may be used together to determine the heating and improve patient safety online.

  9. Transcranial thermoacoustic tomography: a comparison of two imaging algorithms.

    PubMed

    Liu, Zijian; Liu, Lanbo; Xu, Yuan; Wang, Lihong Victory

    2013-02-01

    Thermoacoustic tomography (TAT) is a novel, non-invasive medical imaging technique but has encountered obstacles in imaging through the cranium. In this paper we present two methods for transcranial TAT: Kirchhoff migration (KM) and reverse-time migration (RTM). The two methods' imaging qualities are verified and compared based on both synthetic and experimental data. RTM proves to have better velocity variance and imaging quality, and little noise with spatial aliasing. RTM is a promising approach for achieving transcranial TAT in further studies. PMID:23076033

  10. The role of medial prefrontal cortex in theory of mind: a deep rTMS study.

    PubMed

    Krause, Laura; Enticott, Peter G; Zangen, Abraham; Fitzgerald, Paul B

    2012-03-01

    Neuroimaging studies suggest that the medial prefrontal cortex (mPFC) plays a central role in cognitive theory of mind (ToM). This can be assessed more definitively, however, using repetitive transcranial magnetic stimulation (rTMS). Sixteen healthy participants (10 females, 6 males) completed tasks assessing cognitive and affective ToM following low-frequency deep rTMS to bilateral mPFC in active-stimulation and placebo-stimulation sessions. There was no effect of deep rTMS on either cognitive or affective ToM performance. When examining self-reported empathy, however, there was evidence for a double dissociation: deep rTMS disrupted affective ToM performance for those with high self-reported empathy, but improved affective ToM performance for those with low self-reported empathy. mPFC appears to play a role in affective ToM processing, but the present study suggest that stimulation outcomes are dependent on baseline empathic abilities. PMID:22155478

  11. Magnetic Resonance Techniques Applied to the Diagnosis and Treatment of Parkinson’s Disease

    PubMed Central

    de Celis Alonso, Benito; Hidalgo-Tobón, Silvia S.; Menéndez-González, Manuel; Salas-Pacheco, José; Arias-Carrión, Oscar

    2015-01-01

    Parkinson’s disease (PD) affects at least 10 million people worldwide. It is a neurodegenerative disease, which is currently diagnosed by neurological examination. No neuroimaging investigation or blood biomarker is available to aid diagnosis and prognosis. Most effort toward diagnosis using magnetic resonance (MR) has been focused on the use of structural/anatomical neuroimaging and diffusion tensor imaging (DTI). However, deep brain stimulation, a current strategy for treating PD, is guided by MR imaging (MRI). For clinical prognosis, diagnosis, and follow-up investigations, blood oxygen level-dependent MRI, DTI, spectroscopy, and transcranial magnetic stimulation have been used. These techniques represent the state of the art in the last 5?years. Here, we focus on MR techniques for the diagnosis and treatment of Parkinson’s disease.

  12. Clinical application of transcranial Doppler monitoring for embolic signals

    Microsoft Academic Search

    M. R. Azarpazhooh; B. R. Chambers

    2006-01-01

    A major advantage of transcranial ultrasound is its suitability for continuous monitoring. Microembolic signals (MES) are brief, high-intensity transients that occur when particulate microemboli or gaseous microbubbles pass through the ultrasound beam. These MES have been detected in several clinical scenarios, but rarely in age-matched controls. The detection of MES provides important pathophysiological information in a variety of disorders, but

  13. Transcranial Ultrasound in Acute Stroke: From Diagnosis to Therapy

    Microsoft Academic Search

    Carlos A. Molina; Andrei V. Alexandrov

    2007-01-01

    In the last few years, several studies have improved our knowledge and understanding of the dynamic nature of the recanalization process during stroke thrombolysis. Transcranial Doppler ultrasound provides a unique opportunity to assess several aspects of clot dissolution by means of continuous monitoring of recanalization during and after administration of tissue plasminogen activator. This approach allows us to evaluate at

  14. Behavioral/Cognitive Bihemispheric Transcranial Direct Current Stimulation

    E-print Network

    Diedrichsen, Jörn

    these into purposeful sequences. Although transcranial direct current stimulation (tDCS) of the primary motor cortex (M1 facilitate motor synergy learning. Here, we determined the effects of tDCS on the learning of motor synergies patterns. Bihemispheric tDCS was applied to M1 of healthy, right-handed human participants during 4 d

  15. RESEARCH Open Access Facilitating myoelectric-control with transcranial

    E-print Network

    Paris-Sud XI, Université de

    treatment at the central nervous system (CNS) level with transcranial direct current stimulation (tDCS: This study on 12 healthy volunteers was conducted to investigate the effects of anodal tDCS of the primary' trials showed a significant main effect of the anodal tDCS target: cerebellar, M1, sham (F(2) = 2.33, p

  16. Transcranial direct current stimulation: State of the art 2008

    E-print Network

    Miall, Chris

    . Beyond this, transcranial direct current stimulation (tDCS) of different cortical areas has been shown and standardize future tDCS studies, we offer this overview of the state of the art for tDCS. Ó 2008 Elsevier Inc. All rights reserved. Keywords tDCS; brain; human; neuroplasticity Application of electrical currents

  17. Extraction of Fronto-orbital Shower Hook through Transcranial Orbitotomy.

    PubMed

    Elia, Maxwell D; Gunel, Murat; Servat, Juan J; Levin, Flora

    2014-06-01

    Transorbital foreign bodies threaten both the integrity of the globe and the brain. We present an unusual case of a penetrating right frontal lobe-orbital metallic shower hook. Extensive intracranial involvement necessitated transcranial orbitotomy allowing for the removal of the object without loss of the globe. PMID:25050150

  18. Postpartum Cerebral Angiopathy: Reversible Vasoconstriction Assessed by Transcranial Doppler Ultrasounds

    Microsoft Academic Search

    J. Bogousslavsky; P. A. Despland; F. Regli; P. Y. Dubuis

    1989-01-01

    Postpartum cerebral angiopathy is a distinct reversible clinicoradiological syndrome which develops shortly after a normal pregnancy. It may belong to the poorly defined group of acute benign cerebral angiopathy, in which multisegmental narrowings of cerebral arteries are also reversible. In a 22-year-old woman with postpartum cerebral angiopathy, sequential transcranial Doppler ultrasounds showed that the flow disturbances began to improve 4

  19. Transcranial Doppler Ultrasound in Children with Sturge-Weber Syndrome

    Microsoft Academic Search

    Lori C. Jordan; Robert J. Wityk; Michael M. Dowling; M. Robert DeJong; Anne M. Comi

    2008-01-01

    Transcranial Doppler ultrasound is a noninvasive vascular assessment technique proved useful in the management of pediatric disorders predisposed to stroke and may have similar utility for Sturge-Weber syndrome. Eight children with Sturge-Weber syndrome had velocities measured in the major cerebral arteries via the Stroke Prevention Trial in Sickle Cell Anemia methodology. Velocities and pulsatility indexes were compared between the unaffected

  20. Transcranial direct current stimulation in adolescent and adult Rasmussen's encephalitis

    Microsoft Academic Search

    Juan de Dios Del Castillo Calcáneo; Maricarmen Fernández González-Aragón; Luis Bermúdez Maldonado; Álvaro Moreno Avellán; Edgar Valentín Gómez Argumosa; Felipe Fregni

    2011-01-01

    Rasmussen's encephalitis is a rare, progressive inflammatory disease that typically affects one cerebral hemisphere and causes intractable partial-onset seizures. Currently, the only effective therapy is hemispherectomy; however, this procedure is associated with irreversible neurological deficits. Novel therapeutic approaches to this condition are therefore necessary. One possible option that has not yet been extensively studied is electrical cathodal transcranial direct current

  1. Improvement of spatial tactile acuity by transcranial direct current stimulation

    Microsoft Academic Search

    Patrick Ragert; Yves Vandermeeren; Mickael Camus; Leonardo G. Cohen

    2008-01-01

    ObjectiveNon-invasive brain stimulation such as transcranial direct current stimulation (tDCS) has been successfully used to induce polarity-specific excitability changes in the brain. However, it is still unknown if anodal tDCS (tDCSanodal) applied to the primary somatosensory cortex (S1) can lead to behavioral changes in performance of tactile discriminative tasks.

  2. Safety limits of cathodal transcranial direct current stimulation in rats

    Microsoft Academic Search

    David Liebetanz; Reinhard Koch; Susanne Mayenfels; Fatima König; Walter Paulus; Michael A. Nitsche

    2009-01-01

    ObjectiveThe aim of this rat study was to investigate the safety limits of extended transcranial direct current stimulation (tDCS). tDCS may be of therapeutic value in several neuro-psychiatric disorders. For its clinical applicability, however, more stable effects are required, which may be induced by intensified stimulations.

  3. Random calibration for accelerating MR-ARFI guided ultrasonic focusing in transcranial therapy

    NASA Astrophysics Data System (ADS)

    Liu, Na; Liutkus, Antoine; Aubry, Jean-François; Marsac, Laurent; Tanter, Mickael; Daudet, Laurent

    2015-02-01

    Transcranial focused ultrasound is a promising therapeutic modality. It consists of placing transducers around the skull and emitting shaped ultrasound waves that propagate through the skull and then concentrate on one particular location within the brain. However, the skull bone is known to distort the ultrasound beam. In order to compensate for such distortions, a number of techniques have been proposed recently, for instance using Magnetic Resonance Imaging feedback. In order to fully determine the focusing distortion due to the skull, such methods usually require as many calibration signals as transducers, resulting in a lengthy calibration process. In this paper, we investigate how the number of calibration sequences can be significantly reduced, based on random measurements and optimization techniques. Experimental data with six human skulls demonstrate that the number of measurements can be up to three times lower than with the standard methods, while restoring 90% of the focusing efficiency.

  4. Improved parameterization of the transcranial Doppler signal.

    PubMed

    Schaafsma, Arjen

    2012-08-01

    The great potential of transcranial Doppler (TCD) as a tool for neuromonitoring is limited by the current parameterization of the signal. This article proposes a set of new parameters that more accurately represents the shape of the waveform and eliminates a number of confounding factors. This set of parameters was tested in 227 patients with ipsilateral carotid artery stenosis and compared with 31 normal subjects recruited at our laboratory. From the TCD waveform, we calculated on a beat-to-beat basis the maximal change in flow velocity at stroke onset (acceleration or acc), the maximal flow velocity during the first 100 ms of systole (sys1) and the maximal flow velocity in the remaining part of systole (sys2). All data were normalized relative to the mean diastolic flow velocity over an interval ranging from 520 till 600 ms after stroke onset (dias@560). For the group with carotid stenosis compared with the normal controls the average ± SD for acc (20.2 ± 9.5 vs. 20.2 ± 6.7; p = 0.98) and sys1 (1.82 ± 0.38 vs. 1.77 ± 0.56; p = 0.35) did not differ significantly. The average ±SD for sys2 (1.94 ± 0.33 vs. 1.50 ± 0.12; p < 0.001), however, was significantly higher in the group with carotid stenosis than in the group of normal subjects. The difference between sys1 and sys2 ("sys1-sys2") was lower in the patient group than in controls (-0.12 ± 0.16 vs. 0.27 ± 0.22; p < 0.001). For the acc, there was a significantly higher variance in the group with stenosis than without (p < 0.001). Of the old parameters, the beat-to-beat mean (37.0 ± 13.1 vs. 41.3 ± 15.9; p = 0.17) and the pulsatility index (PI; 1.00 ± 0.26 vs. 0.91 ± 0.23; p = 0.06) were not significantly different between groups. Graphed together the acc and "sys1-sys2" parameters allowed a clear demarcation of both groups whereas in a graph of the old parameters mean and PI both groups overlapped considerably. In conclusion, the proposed set of new parameters not only has theoretical and practical benefits but also has excellent discriminative power in a group of carotid patients compared with normal controls. PMID:22579541

  5. Transcranial magnetic stimulation studies of visuospatial attentional control

    E-print Network

    Kastner, Sabine

    processing in the brain, creating a brief `virtual lesion'. Here, we review recent studies that have employed processing, creating a `virtual lesion' in the latter case. As a consequence, it is possible to alter changes depending on the shape and orientation of the coil and the underlying brain anatomy

  6. Behavioral/Systems/Cognitive Posttraining Transcranial Magnetic Stimulation of Striate

    E-print Network

    Crawford, Doug

    phase driven by high-level areas is followed by a late, asymptotic learning phase driven by low-level the robustness is controlled by high-level, contextual factors. Introduction The neural mechanisms driving extending beyond daily training ses- sions. According to visual learning theories, an early, fast learning

  7. Noninvasive remote activation of the ventral midbrain by transcranial direct current stimulation of prefrontal cortex.

    PubMed

    Chib, V S; Yun, K; Takahashi, H; Shimojo, S

    2013-01-01

    The midbrain lies deep within the brain and has an important role in reward, motivation, movement and the pathophysiology of various neuropsychiatric disorders such as Parkinson's disease, schizophrenia, depression and addiction. To date, the primary means of acting on this region has been with pharmacological interventions or implanted electrodes. Here we introduce a new noninvasive brain stimulation technique that exploits the highly interconnected nature of the midbrain and prefrontal cortex to stimulate deep brain regions. Using transcranial direct current stimulation (tDCS) of the prefrontal cortex, we were able to remotely activate the interconnected midbrain and cause increases in participants' appraisals of facial attractiveness. Participants with more enhanced prefrontal/midbrain connectivity following stimulation exhibited greater increases in attractiveness ratings. These results illustrate that noninvasive direct stimulation of prefrontal cortex can induce neural activity in the distally connected midbrain, which directly effects behavior. Furthermore, these results suggest that this tDCS protocol could provide a promising approach to modulate midbrain functions that are disrupted in neuropsychiatric disorders. PMID:23756377

  8. Monsoon variability and deep oceanic circulation in the western equatorial Pacific over the last climatic cycle: Insights from sedimentary magnetic properties and sortable silt

    NASA Astrophysics Data System (ADS)

    Kissel, Catherine; Laj, Carlo; Kienast, Markus; Bolliet, Timothé; Holbourn, Ann; Hill, Paul; Kuhnt, Wolfgang; Braconnot, Pascale

    2010-09-01

    Magnetic and grain size properties of a sediment core located in the western equatorial Pacific, off the southeastern tip of the Philippine island of Mindanao, are presented in an effort to reconstruct past changes in the East Asian Monsoon and deep ocean circulation during the last 160 kyrs. The sedimentary concentration of magnetic particles, interpreted to reflect past changes in runoff from Mindanao, varies almost in antiphase with Northern Hemisphere insolation. This suggests that precipitation was lower in the western equatorial Pacific region during boreal insolation maxima and thus corroborates model results showing opposing trends in precipitation between land and the marine realm there. Variations in the grain size distribution of the inorganic sediment fraction, as recorded by both the sortable silt mean size and the magnetic grain size, provide a monitor of changes in sediment reworking by bottom currents. The close correlation of this proxy of bottom current strength and the benthic ?18O record from the same site implies a tight coupling between deep water flow, most likely Antarctic Intermediate Water (AAIW), and global climate.

  9. Magnetotelluric and Surface Nuclear Magnetic Resonance Measurements of Regional and Local Variability of Deep Saline Permafrost in Adventdalen, Svalbard

    NASA Astrophysics Data System (ADS)

    Bense, V.; Binley, A. M.; Keating, K.; Van Dam, R. L.; Christiansen, H. H.; Cohen, S.; McGuffy, C.

    2014-12-01

    In most Arctic areas the interplay between permafrost and parameters such as climate variability and geological history is not well understood or documented. Nevertheless, knowledge on the thermal state of permafrost, its thickness and ice/water content is crucial for a credible assessment of the impacts of surface warming on a suite of environmental processes such as groundwater flow to riverbeds and the release of methane from areas of degrading permafrost. We carried out geophysical surveys using non-invasive Magnetotelluric (MT) and Surface Nuclear Magnetic Resonance (SNMR) techniques to map permafrost occurrence in Adventdalen, Svalbard, a river valley in a typical coastal Arctic landscape. MT, which is sensitive to changes in the electrical conductivity and can be used to distinguish saline, fresh, and frozen soils, was used to determine the total thickness of permafrost (potentially several 100s of meters). SNMR, which is directly sensitive the volume of liquid water, was used to determine the unfrozen water content and the heterogeneity of permafrost at depths of up to ~100 m. We collected measurements in transects across and along the valley which is filled with Holocene estuarine sediments. MT observations suggest that permafrost thickens substantially to up to several hundreds of meters along the ~12 km long transect from the coastal area inland. The electrical resistivities observed are relatively low (~200-400 ?m) when compared to permafrost environments in Alpine settings, which is most likely attributed to a high salinity of pore waters in our study area. In the parts of the valley above the marine limit (~70 m above sea-level) SNMR did not detect any unfrozen water content. However, closely spaced SNMR transects across the valley several kilometers from the coast show a substantial signal, potentially due to unfrozen water content in supra-permafrost taliks near the main river channel. This is the first study to illustrate the ability of combining MT and SNMR data to map permafrost characteristics in saline environments. Combining these geophysical measurements with auxiliary data on the pore water salinities, temperature and the geological makeup of the study area will allow a thorough determination of ice-content and thermal state of deep permafrost in this coastal permafrost environment.

  10. Frontal Bone Windows for Transcranial Color-Coded Duplex Sonography

    Microsoft Academic Search

    Erwin Stolz; Manfred Kaps; Andeas Kern; Wolfgang Dorndorf

    Background and Purpose—The use of the conventional temporal bone window for transcranial color-coded duplex sonography (TCCS) often results in difficulties in obtaining angle-corrected flow velocity measurements of the A2 segment of the anterior cerebral artery, the posterior communicating artery, and the midline venous vasculature because of the unfavorable insonation angle. The same applies to B-mode imaging of the frontal parenchyma.

  11. Transcranial ultrasound-improved thrombolysis: diagnostic vs. therapeutic ultrasound

    Microsoft Academic Search

    Stephan Behrens; Konstantinos Spengos; Michael Daffertshofer; Helmut Schroeck; Carl E Dempfle; Michael Hennerici

    2001-01-01

    Success of stroke treatment with rt-PA depends on rapid vessel recanalization. Enzymatic thrombolysis may be enhanced by additional transcranial application of ultrasound (US). We investigated this novel technique using a 185-kHz probe and compared it to standard diagnostic US. In vitro studies were performed in a continuous pressure tubing system. Clots were placed in a postmortem skull and treated with

  12. Transcranial Extracellular Impedance Control (tEIC) Modulates Behavioral Performances

    PubMed Central

    Matani, Ayumu; Nakayama, Masaaki; Watanabe, Mayumi; Furuyama, Yoshikazu; Hotta, Atsushi; Hoshino, Shotaro

    2014-01-01

    Electric brain stimulations such as transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS), and transcranial alternating current stimulation (tACS) electrophysiologically modulate brain activity and as a result sometimes modulate behavioral performances. These stimulations can be viewed from an engineering standpoint as involving an artificial electric source (DC, noise, or AC) attached to an impedance branch of a distributed parameter circuit. The distributed parameter circuit is an approximation of the brain and includes electric sources (neurons) and impedances (volume conductors). Such a brain model is linear, as is often the case with the electroencephalogram (EEG) forward model. Thus, the above-mentioned current stimulations change the current distribution in the brain depending on the locations of the electric sources in the brain. Now, if the attached artificial electric source were to be replaced with a resistor, or even a negative resistor, the resistor would also change the current distribution in the brain. In light of the superposition theorem, which holds for any linear electric circuit, attaching an electric source is different from attaching a resistor; the resistor affects each active electric source in the brain so as to increase (or decrease in some cases of a negative resistor) the current flowing out from each source. From an electrophysiological standpoint, the attached resistor can only control the extracellular impedance and never causes forced stimulation; we call this technique transcranial extracellular impedance control (tEIC). We conducted a behavioral experiment to evaluate tEIC and found evidence that it had real-time enhancement and depression effects on EEGs and a real-time facilitation effect on reaction times. Thus, tEIC could be another technique to modulate behavioral performance. PMID:25047913

  13. Transcranial colour-coded duplex sonography of cerebral arteriovenous malformations

    Microsoft Academic Search

    R. W. Baumgartner; H. P. Mattle; G. Schroth

    1996-01-01

    A transcranial colour-coded duplex sonography (TCCD) study was performed to evaluate the sensitivity of detection and the\\u000a feasibility of visualising details of cerebral arteriovenous malformations (AVMs). We prospectively examined 15 patients with\\u000a 2 large (> 4 cm), 7 medium-size (2–4 cm) and 6 small (< 2 cm) radiologically proven supratentorial AVMs of the brain using\\u000a TCCD. A feeding vessel was

  14. Evaluation of flow velocity in unilateral middle cerebral artery stenosis by Transcranial Doppler.

    PubMed

    Wang, Lin; Xing, Yingqi; Li, Yang; Han, Ke; Chen, Jiafeng

    2014-11-01

    To determine the optimal velocity values in diagnosing unilateral middle cerebral artery (MCA) stenosis by Transcranial Doppler (TCD), and improve the diagnostic accuracy using magnetic resonance angiography (MRA), a total of 302 unilateral MCA stenosis patients undergoing TCD also consented to a MRA of the intracranial arteries. The peak systolic velocity (PSV) and each MCA spectrum for each patient were recorded. Using the MRA to confirm, the degree of middle cerebral artery stenosis was categorized into four groups: normal (normal caliber and signal), mild (<50 %), moderate (50-69 %), severe (70-99 %, or no flow detected). The velocity difference among these four groups was significant (P < 0.001). The optimal PSV values for normal and stenosis were 160 cm/s. For mild and moderate were 200 cm/s, for moderate and severe were 280 cm/s. Using PSV as the diagnostic criteria, the Kappa number was >0.668. The optimal PSV differential value for mild and moderate was 70 cm/s, for moderate and severe at 120 cm/s. Optimal combined criteria for moderate stenosis were PSV >200 cm/s and PSV differential value >70 cm/s (specificity 87.2 %), for severe stenosis were PSV >280 cm/s and PSV differential value >120 cm/s (sensibility 81.6 %). Transcranial Doppler distinguishes normal and MCA stenosis with a reduced lumen diameter of less than 50 %. Using the PSV criteria, TCD has a high coincidence rate with MRA in the diagnosis of MCA stenosis. Combined PSV differential value and the abnormal spectrum may improve the accuracy of TCD in diagnosing moderate or severe stenosis. PMID:24833432

  15. Transcranial phase aberration correction using beam simulations and MR-ARFI

    SciTech Connect

    Vyas, Urvi, E-mail: urvi.vyas@gmail.com; Kaye, Elena; Pauly, Kim Butts [Department of Radiology, Stanford University, Stanford, California 94305 (United States)] [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

    2014-03-15

    Purpose: Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-ARFI technique to achieve aberration correction for transcranial MR-guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR-ARFI) to correct skull-caused phase aberrations. Methods: Skull-based numerical aberrations were obtained from a MR-guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR-ARFI images were used in the hybrid simulation-MR-ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16-aberration and 1024-aberration) was repeated three times. Results: The corrected MR-ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation-MR-ARFI technique resulted in an average increase in focal MR-ARFI phase of 44% for the 16-aberration case and 52% for the 1024-aberration case, and recovered 83% and 39% of the ideal MR-ARFI phase for the 16-aberrations and 1024-aberration case, respectively. Conclusions: Using one MR-ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation-MR-ARFI technique improved the maximum MR-ARFI phase of the beam's focus.

  16. Neuroplastic effects of transcranial near-infrared stimulation (tNIRS) on the motor cortex

    PubMed Central

    Chaieb, Leila; Antal, Andrea; Masurat, Florentin; Paulus, Walter

    2015-01-01

    Near-infrared light stimulation of the brain has been claimed to improve deficits caused by traumatic brain injury and stroke. Here, we exploit the effect of transcranial near-infrared stimulation (tNIRS) as a tool to modulate cortical excitability in the healthy human brain. tNIRS was applied at a wavelength of 810 nm for 10 min over the hand area of the primary motor cortex (M1). Both single-pulse and paired-pulse measures of transcranial magnetic stimulation (TMS) were used to assess levels of cortical excitability in the corticospinal pathway and intracortical circuits. The serial reaction time task (SRTT) was used to investigate the possible effect of tNIRS on implicit learning. By evaluating the mean amplitude of single-pulse TMS elicited motor-evoked-potentials (MEPs) a significant decrease of the amplitude was observed up to 30 min post-stimulation, compared to baseline. Furthermore, the short interval cortical inhibition (SICI) was increased and facilitation (ICF) decreased significantly after tNIRS. The results from the SRTT experiment show that there was no net effect of stimulation on the performance of the participants. Results of a study questionnaire demonstrated that tNIRS did not induce serious side effects apart from light headache and fatigue. Nevertheless, 66% were able to detect the difference between active and sham stimulation conditions. In this study we provide further evidence that tNIRS is suitable as a tool for influencing cortical excitability and activity in the healthy human brain. PMID:26082699

  17. Comparison of transcranial color Doppler imaging (TCDI) and transcranial Doppler (TCD) in children with sickle-cell anemia

    Microsoft Academic Search

    A. M. Jones; Joanna J. Seibert; Fenwick T. Nichols; David L. Kinder; Katie Cox; Judy Luden; Elizabeth M. Carl; Donald Brambilla; Suzanne Saccente; Robert J. Adams

    2001-01-01

    Background. Transcranial Doppler (TCD) has been demonstrated to identify those at highest risk of stroke among children with sickle-cell\\u000a disease. Based on a randomized clinical trial [Stroke Prevention in Sickle-Cell Anemia Trial (STOP)], which ended in 1997,\\u000a the National Heart Lung and Blood Division of NIH has recommended TCD screening and chronic blood transfusion based on Nicolet\\u000a TC 2000 dedicated

  18. MULTIPLE FEATURE EXTRACTION FOR EARLY PARKINSON RISK ASSESSMENT BASED ON TRANSCRANIAL SONOGRAPHY IMAGE

    E-print Network

    Lübeck, Universität zu

    MULTIPLE FEATURE EXTRACTION FOR EARLY PARKINSON RISK ASSESSMENT BASED ON TRANSCRANIAL SONOGRAPHY for the diagnosis of Parkinson's disease (PD) at a very early state. The TCS im- age of mesencephalon shows, Parkinson's Disease, Transcranial sonography, classification, texture analysis 1. INTRODUCTION Early

  19. In vivo transcranial cavitation threshold detection during ultrasound-induced bloodbrain barrier opening in mice

    E-print Network

    Konofagou, Elisa E.

    In vivo transcranial cavitation threshold detection during ultrasound-induced blood­brain barrier cavitation threshold detection during ultrasound-induced blood­brain barrier opening in mice Yao-Sheng Tung1 cavitation response associated with blood­brain barrier (BBB) opening as induced by transcranial focused

  20. Transcranial direct current stimulation over posterior parietal cortex modulates visuospatial localization

    E-print Network

    Krekelberg, Bart

    , our goal was to determine whether modulation of the PPC via transcranial direct current stimulation (tDCS the left PPC (dual tDCS) and varied the polarity of the stimulation. We found that this manipulation localization. We used transcranial direct current stimulation (tDCS) over the PPC of healthy human volunteers

  1. EFFECTS OF TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) ON SENSORY EVOKED POTENTIALS: A COMPUTATIONAL MODELING

    E-print Network

    Paris-Sud XI, Université de

    EFFECTS OF TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) ON SENSORY EVOKED POTENTIALS/computational modeling approach aimed at studying the effects of transcranial Direct Current Stimulation (tDCS (EPs) recorded from the somatosensory cortex of the rabbit under tDCS. Results showed that the model

  2. On the Role of Electric Field Orientation in Optimal Design of Transcranial Current Stimulation

    E-print Network

    Parra, Lucas C.

    On the Role of Electric Field Orientation in Optimal Design of Transcranial Current Stimulation , and Lucas C. Parra 1 Abstract-- Transcranial current stimulation (tCS) is a promising noninvasive technique algorithm which computes the montage maximizing directed current flow at the target. The results reveal

  3. Categorization is modulated by transcranial direct current stimulation over left prefrontal cortex

    E-print Network

    Thompson-Schill, Sharon

    Categorization is modulated by transcranial direct current stimulation over left prefrontal cortex transcranial direct current stimulation alters performance of healthy subjects on a simple categoriza- tion of multiple catego- ries. A given object, such as a pillow may be--depending on current task demands

  4. How Deep Is Deep?

    NSDL National Science Digital Library

    This interactive online tool helps students grasp just how deep scientists must dive to study deep sea vents. By providing points of comparison, it puts the nearly unfathomable depth of the ocean floor into perspective. It compares the scale of a 2,400-meter (7,874-foot) dive against the height of famous landmarks such as the Empire State Building, the Eiffel Tower, and the Space Needle. Students can also enter the height, in feet or meters, of any landmark they choose to gain additional perspective.

  5. Effects of cathodal transcranial direct current stimulation to primary somatosensory cortex on short-latency afferent inhibition.

    PubMed

    Kojima, Sho; Onishi, Hideaki; Miyaguchi, Shota; Kotan, Shinichi; Sugawara, Kazuhiro; Kirimoto, Hikari; Tamaki, Hiroyuki

    2015-08-01

    The aim of this study was to investigate the effects of cathodal transcranial direct current stimulation (tDCS) applied over the primary somatosensory cortex (S1) on short-interval afferent inhibition (SAI). Thirteen healthy individuals participated in this study. Cathodal tDCS was applied for 15?min at 1?mA over the left S1. Motor-evoked potentials (MEPs) were measured from the right first dorsal interosseous muscle in response to transcranial magnetic stimulation (TMS) of the left motor cortex before tDCS (pre), immediately after tDCS (immediately), and 15?min after tDCS (post-15?min). SAI was evaluated by measuring MEPs in response to TMS pulses applied 40?ms after peripheral electrical stimulation of the index finger. For each measurement period (pre, immediately, and post-15?min), MEP amplitude was significantly smaller when TMS followed index finger stimulation (SAI condition) than when TMS was delivered alone (single TMS) (P<0.01), indicating expression of SAI. The MEP ratio (MEP of SAI/MEP of single TMS) at post-15?min was significantly larger than that of pre (P<0.05), indicating suppression of SAI. However, no significant difference was observed between pre and immediately, and immediately and post-15?min. These results suggest that cathodal tDCS applied over the S1 causes a decrease in S1 excitability following peripheral electrical stimulation and cathodal tDCS applied over the S1 decreased the inhibitory effects of SAI. PMID:26103117

  6. Insights into Oceanic Crust Accretion from a Comparison of Rock Magnetic and Silicate Fabrics from Lower Crustal Gabbros from Hess Deep Rift

    NASA Astrophysics Data System (ADS)

    Horst, A. J.; Morris, A.; Friedman, S. A.; Cheadle, M. J.

    2014-12-01

    The mechanisms of lower crustal accretion remain a long-standing question for those who study fast-spreading mid-ocean ridges. One of the goals of Integrated Ocean Drilling Program (IODP) Expedition 345 is to test accretionary models by investigating the structure of the lower oceanic crust exposed within the Hess Deep Rift. Located near the tip of the westward-propagating Cocos-Nazca spreading center, Hess Deep Rift exposes crust formed at the East Pacific Rise. During IODP Expedition 345, primitive gabbroic rocks were recovered from a dismembered lower crustal section at ~4850 meters below sealevel. Constraints on physical processes during magmatic accretion are provided by the relative orientation and strength of rock fabrics. We present anisotropy of magnetic susceptibility (AMS) fabric data from gabbros recovered from the two deepest holes (U1415J and U1415P). AMS measurements provide petrofabric data that may be used to constrain magma emplacement and subsequent magmatic flow. Bulk susceptibility ranges from 1.15 x 10-4 to 5.73 x 10-2 SI, with a majority of the samples having susceptibility greater than 10-3 SI, suggesting magnetite is the dominant contributor to the AMS signal. Low-temperature demagnetization data show Verwey transitions near 125K indicating the presence of nearly stoichiometric magnetite in most samples. AMS reveals dominantly oblate fabrics with a moderate degree of anisotropy (P') ranging from 1.01 to 1.38 (average P' = 1.13). Fabric strength varies within each of the petrologically-defined units recovered from different crustal blocks. Additional remanence anisotropy fabric analyses of a few specimens reveal nearly identical directions of principal axes compared to AMS, but with larger degrees of anisotropy. Electron backscatter diffraction (EBSD) data from one sample shows a moderate plagioclase crystallographic preferred orientation best defined by a b-axis maxima that is coincident with the AMS minimum principal axis. This comparison between silicate and magnetic fabric data suggests that AMS is a good proxy for bulk silicate fabrics in these samples from Hess Deep. By integrating AMS and EBSD, both sensitive indicators of magnetic and silicate fabrics in gabbroic rocks, we seek a better understanding of the formation of gabbro in oceanic crust.

  7. Transcranial sonography and functional imaging in glucocerebrosidase mutation Parkinson disease

    PubMed Central

    Barrett, MJ; Hagenah, J; Dhawan, V; Peng, S; Stanley, K; Raymond, D; Deik, A; Gross, SJ; Schreiber-Agus, N; Mirelman, A; Marder, K; Ozelius, LJ; Eidelberg, D; Bressman, SB; Saunders-Pullman, R

    2012-01-01

    Background Heterozygous glucocerebrosidase (GBA) mutations are the leading genetic risk factor for Parkinson disease, yet imaging correlates, particularly transcranial sonography, have not been extensively described. Methods To determine whether GBA mutation heterozygotes with Parkinson disease demonstrate hyperechogenicity of the substantia nigra, transcranial sonography was performed in Ashkenazi Jewish Parkinson disease subjects, tested for the eight most common Gaucher disease mutations and the LRRK2 G2019S mutation, and in controls. [18F]-fluorodeoxyglucose or [18F]-fluorodopa positron emission tomography is also reported from a subset of Parkinson disease subjects with heterozygous GBA mutations. Results Parkinson disease subjects with heterozygous GBA mutations (n=23) had a greater median maximal area of substantia nigral echogenicity compared to controls (n=34, aSNmax=0.30 vs. 0.18, p=0.007). There was no difference in median maximal area of nigral echogenicity between Parkinson disease groups defined by GBA and LRRK2 genotype: GBA heterozygotes; GBA homozygotes/compound heterozygotes (n=4, aSNmax=0.27); subjects without LRRK2 or GBA mutations (n=32, aSNmax=0.27); LRRK2 heterozygotes/homozyogotes without GBA mutations (n=27, aSNmax=0.28); and GBA heterozygotes/LRRK2 heterozygotes (n=4, aSNmax=0.32, overall p=0.63). In secondary analyses among Parkinson disease subjects with GBA mutations, maximal area of nigral echogenicity did not differ based on GBA mutation severity or mutation number. [18F]-fluorodeoxyglucose (n=3) and [18F]-fluorodopa (n=2) positron emission tomography in Parkinson disease subjects with heterozygous GBA mutations was consistent with findings in idiopathic Parkinson disease. Conclusions Both transcranial sonography and positron emission tomography are abnormal in GBA mutation associated Parkinson disease, similar to other Parkinson disease subjects. PMID:23062841

  8. Microembolus Detection by Transcranial Doppler Sonography: Review of the Literature

    PubMed Central

    Vukovi?-Cvetkovi?, Vlasta

    2012-01-01

    Transcranial Doppler can detect microembolic signals which are characterized by unidirectional high intensity increase, short duration, random occurrence, and a “whistling” sound. Microembolic signals have been detected in a number of clinical settings: carotid artery stenosis, aortic arch plaques, atrial fibrillation, myocardial infarction, prosthetic heart valves, patent foramen ovale, valvular stenosis, during invasive procedures (angiography, percutaneous transluminal angioplasty), surgery (carotid, cardiopulmonary bypass, orthopedic), and in certain systemic diseases. Microembolic signals are frequent in large artery disease, less commonly detected in cardioembolic stroke, and infrequent in lacunar stroke. This article provides an overview about the current state of technical and clinical aspects of microembolus detection. PMID:22195291

  9. Silent period evoked by transcranial stimulation of the human cortex and cervicomedullary junction.

    PubMed Central

    Inghilleri, M; Berardelli, A; Cruccu, G; Manfredi, M

    1993-01-01

    1. The silent period evoked in the first dorsal interosseous (FDI) muscle after electrical and magnetic transcranial stimulation (TCS), electrical stimulation of the cervicomedullary junction and ulnar nerve stimulation was studied in ten healthy subjects. 2. With maximum-intensity shocks, the average duration of the silent period was 200 ms after electrical TCS, 300 ms after magnetic TCS, 43 ms after stimulation at the cervicomedullary junction and 100 ms after peripheral nerve stimulation. 3. The duration of the silent period, the amplitude of the motor-evoked potential, and the twitch force produced in the muscle were compared at increasing intensities of magnetic TCS. When the stimulus strength was increased from 30 to 70% of the stimulator output, the duration of the silent period lengthened as the amplitude of the motor potential and force of the muscle twitch increased. At 70 to 100% of the output, the amplitude of the motor potential and force of the muscle twitch saturated, whereas the duration of the silent period continued to increase. 4. Proximal arm muscle twitches induced by direct electrical stimulation of the biceps and extensor wrist muscles produced no inhibition of voluntary activity in the contracting FDI muscle. 5. The level of background activation had no effect on the duration of the silent period recorded in the FDI muscle after magnetic TCS. 6. Corticomotoneurone excitability after TCS was studied by means of a single magnetic conditioning shock and a test stimulus consisting either of one single magnetic shock or single and double electrical shocks (interstimulus interval 1.8 ms) in the relaxed muscle. A conditioning magnetic shock completely suppressed the response evoked by a second magnetic shock, reduced the size of the response evoked by a single electrical shock but did not affect the response evoked by double electrical shocks. Inhibition of the test magnetic shock was also present during muscle contraction. 7. Our findings indicate that the first 50 ms of the silent period after TCS are produced mainly by spinal mechanisms such as after-hyperpolarization and recurrent inhibition of the spinal motoneurones. If descending inhibitory fibres contribute, their contribution is small. Changes in proprioceptive input probably have a minor influence. From 50 ms onwards the silent period is produced mainly by cortical inhibitory mechanisms. PMID:8410704

  10. Voluntary control of human gait: conditioning of magnetically evoked motor responses in a precision stepping task

    Microsoft Academic Search

    M. Schubert; A. Curt; G. Colombo; W. Berger; V. Dietz

    1999-01-01

    The aim of this study was to investigate visuomotor control during human gait. It was assumed that visual input should modulate\\u000a transcranially evoked motor potentials (EMPs) during walking. The effect of transcranial magnetic stimulation (TMS) in a visually\\u000a guided precision stepping task was compared with that during normal gait. EMPs were studied in tibialis anterior (TA), gastrocnemius\\u000a (GM), and abductor

  11. Improved interfaces and magnetic properties in spin valves using Ni80Fe20 Edward J. Repetski, David X. Yang, Harsh Deep Chopra, P. J. Chen, and W. F. Egelhoff

    E-print Network

    Chopra, Harsh Deep

    Improved interfaces and magnetic properties in spin valves using Ni80Fe20 seed layer Edward J. Repetski, David X. Yang, Harsh Deep Chopra, P. J. Chen, and W. F. Egelhoff Citation: J. Appl. Phys. 91. Related Articles (001) textured L10-FePt pseudo spin valve with TiN spacer Appl. Phys. Lett. 99, 252503

  12. Image reconstruction in transcranial photoacoustic computed tomography of the brain

    NASA Astrophysics Data System (ADS)

    Mitsuhashi, Kenji; Wang, Lihong V.; Anastasio, Mark A.

    2015-03-01

    Photoacoustic computed tomography (PACT) holds great promise for transcranial brain imaging. However, the strong reflection, scattering, attenuation, and mode-conversion of photoacoustic waves in the skull pose serious challenges to establishing the method. The lack of an appropriate model of solid media in conventional PACT imaging models, which are based on the canonical scalar wave equation, causes a significant model mismatch in the presence of the skull and thus results in deteriorated reconstructed images. The goal of this study was to develop an image reconstruction algorithm that accurately models the skull and thereby ameliorates the quality of reconstructed images. The propagation of photoacoustic waves through the skull was modeled by a viscoelastic stress tensor wave equation, which was subsequently discretized by use of a staggered grid fourth-order finite-difference time-domain (FDTD) method. The matched adjoint of the FDTD-based wave propagation operator was derived for implementing a back-projection operator. Systematic computer simulations were conducted to demonstrate the effectiveness of the back-projection operator for reconstructing images in a realistic three-dimensional PACT brain imaging system. The results suggest that the proposed algorithm can successfully reconstruct images from transcranially-measured pressure data and readily be translated to clinical PACT brain imaging applications.

  13. Ultrasound measurement of transcranial distance during head-down tilt

    NASA Technical Reports Server (NTRS)

    Torikoshi, S.; Wilson, M. H.; Ballard, R. E.; Watenpaugh, D. E.; Murthy, G.; Yost, W. T.; Cantrell, J. H.; Chang, D. S.; Hargens, A. R.

    1995-01-01

    Exposure to microgravity elevates blood pressure and flow in the head, which may increase intracranial volume (ICV) and intracranial pressure (ICP). Rhesus monkeys exposed to simulated microgravity in the form of 6 degree head-down tilt (HDT) experience elevated ICP. With humans, twenty-four hours of 6 degree HDT bed rest increases cerebral blood flow velocity relative to pre-HDT upright posture. Humans exposed to acute 6 degree HDT experiments increased ICP, measured with the tympanic membrane displacement (TMD) technique. Other studies suggest that increased ICP in humans and cats causes measurable cranial bone movement across the sagittal suture. Due to the slightly compliant nature of the cranium, elevation of the ICP will increase ICV and transcranial distance. Currently, several non-invasive approaches to monitor ICP are being investigated. Such techniques include TMD and modal analysis of the skull. TMD may not be reliable over a large range of ICP and neither method is capable of measuring the small changes in pressure. Ultrasound, however, may reliably measure small distance changes that accompany ICP fluctuations. The purpose of our study was to develop and evaluate an ultrasound technique to measure transcranial distance changes during HDT.

  14. Electronic and magnetic structures of the postperovskite-type Fe[subscript 2]O[subscript 3] and implications for planetary magnetic records and deep interiors

    E-print Network

    Shim, Sang-Heon Dan

    Recent studies have shown that high pressure (P) induces the metallization of the Fe[superscript 2+]–O bonding, the destruction of magnetic ordering in Fe, and the high-spin (HS) to low-spin (LS) transition of Fe in silicate ...

  15. Cortical Control of Affective Networks

    E-print Network

    Kumar, S.

    Transcranial magnetic stimulation and deep brain stimulation have emerged as therapeutic modalities for treatment refractory depression; however, little remains known regarding the circuitry that mediates the therapeutic ...

  16. The Role of 3T Magnetic Resonance Imaging for Targeting the Human Subthalamic Nucleus in Deep Brain Stimulation for Parkinson Disease.

    PubMed

    Longhi, Michele; Ricciardi, Giuseppe; Tommasi, Giorgio; Nicolato, Antonio; Foroni, Roberto; Bertolasi, Laura; Beltramello, Alberto; Moretto, Giuseppe; Tinazzi, Michele; Gerosa, Massimo

    2015-05-01

    Background?Chronic stimulation of the human subthalamic nucleus (STN) is gradually becoming accepted as a long-term therapeutic option for patients with advanced Parkinson disease (PD).3Tesla (T) magnetic resonance imaging (MRI) improves contrast resolution in basal ganglia nuclei containing high levels of iron, because of magnetic susceptibility effects that increase significantly as the magnetic field gets higher. This phenomenon can be used for better visualization of the STN and may reduce the time necessary for detailed microrecording (MER) mapping, increasing surgery efficacy and lowering morbidity. Objective?The objective of this retrospective study is to analyze a population of 20 deep brain stimulation (DBS) electrode implanted patients with PD divided into two groups in which different targeting methods were used. Methods?Mean age was 56 years (range 37 to 69 years). Mean disease duration was 11.6 years. Mean follow-up was 12 months (range 6 to 36 months). Patients were divided into two groups: Group A contained 6 patients who underwent STN targeting using 1T stereotactic (T1w?+?T2w) MRI plus STN indirect atlas derived targeting. Group B consisted of 14 patients who underwent STN targeting using 3T nonstereotactic (T2w) MRI fused with 1T T1w stereotactic MRI and STN direct targeting. For statistical analysis, we compared (five different parameters in both (matched) groups: Unified Parkinson's disease rating scale (UPDRS) score reduction (medication off before surgery against stimulation on/medication off after surgery), postoperative drug reduction, duration of surgery, the "central preoperative track" chosen as final implantation track during surgery, and correspondence between the targeted STN and the intraoperative neurophysiologic data. Results?Mean UPDRS III score reduction (medication off/stimulation on versus preoperative medication off) was 69% in Group A and 74% in Group B (p?=?0.015, log-rank test) respectively. Postoperatively, antiparkinsonian treatment was reduced by 66% in Group A and 75% in Group B (p?=?0.006, log-rank test). The preoperative "central" track (which corresponds to ideal STN targeting) proved to be the most clinically effective in 2/12 leads for Group A versus 21/28 for Group B (p?deepness (and prevent clinical side effects. PMID:25764475

  17. Magnetic Stimulation of One-Dimensional Neuronal Cultures Assaf Rotem and Elisha Moses

    E-print Network

    Moses, Elisha

    Magnetic Stimulation of One-Dimensional Neuronal Cultures Assaf Rotem and Elisha Moses Weizmann Institute of Science, Physics of Complex Systems, Rehovot, Israel ABSTRACT Transcranial magnetic stimulation. Surprisingly, application of the same magnetic stimulation directly to neurons that are dissected from

  18. Transcranial direct current stimulation for the treatment of focal hand dystonia.

    PubMed

    Benninger, David H; Lomarev, Mikhail; Lopez, Grisel; Pal, Natassja; Luckenbaugh, David A; Hallett, Mark

    2011-08-01

    The treatment of writer's cramp, a task-specific focal hand dystonia, needs new approaches. A deficiency of inhibition in the motor cortex might cause writer's cramp. Transcranial direct current stimulation modulates cortical excitability and may provide a therapeutic alternative. In this randomized, double-blind, sham-controlled study, we investigated the efficacy of cathodal stimulation of the contralateral motor cortex in 3 sessions in 1 week. Assessment over a 2-week period included clinical scales, subjective ratings, kinematic handwriting analysis, and neurophysiological evaluation. Twelve patients with unilateral dystonic writer's cramp were investigated; 6 received transcranial direct current and 6 sham stimulation. Cathodal transcranial direct current stimulation had no favorable effects on clinical scales and failed to restore normal handwriting kinematics and cortical inhibition. Subjective worsening remained unexplained, leading to premature study termination. Repeated sessions of cathodal transcranial direct current stimulation of the motor cortex yielded no favorable results supporting a therapeutic potential in writer's cramp. PMID:21495074

  19. Manipulating neuronal activity with low frequency transcranial ultrasound

    NASA Astrophysics Data System (ADS)

    Moore, Michele Elizabeth

    Stimulation of the rodent cerebral cortex is used to investigate the underlying biological basis for the restorative effects of slow wave sleep. Neuronal activation by optogenetic and ultrasound stimulation elicits changes in action potentials across the cerebral cortex that are recorded as electroencephalograms. Optogenetic stimulation requires an invasive implantation procedure limiting its application in human studies. We sought to determine whether ultrasound stimulation could be as effective as optogenetic techniques currently used, in an effort to further understand the physiological and metabolic requirements of sleep. We successfully recorded electroencephalograms in response to transcranial ultrasound stimulation of the barrel cortex at 1 and 7 Hz frequencies, comparing them to those recorded in response to optogenetic stimuli applied at the same frequencies. Our results showed application of a 473 nm blue LED positioned 6 cm above the skull and ultrasound stimulation at an output voltage of 1000 mVpp produced electroencephalograms with physiological responses of similar amplitude. We concluded that there exists an intensity-proportionate response in the optogenetic stimulation, but not with ultrasound stimulation at the frequencies we surveyed. Activation of neuronal cells in response to optogenetic stimulation in a Thy1-ChR2 transgenic mouse line is specifically targeted to pyramidal cells in the cerebral cortex. ChR2 responses to optogenetic stimulation are mediated by a focal activation of neuronal ion channels. We measured electrophysiological responses to ultrasound stimulation, comparing them to those recorded from optogenetic stimuli. Our results show striking similarities between ultrasound-induced responses and optogenetically-induced responses, which may indicate that transcranial ultrasound stimulation is also mediated by ion channel dependent processes in cerebral cortical neurons. The biophysical substrates for electrical excitability of neurons impose temporal constraints on their response to stimulation. If ultrasound-mediated responses are, in fact, ion channel mediated responses, ultrasound-induced responses should exhibit time-dependence characteristics similar to those of optogenetically-triggered responses. Minimal stimulus duration thresholds and the temporal limits of paired pulse facilitation for ultrasound stimulation were identical to those of optogenetic stimulation. Collectively, these experiments demonstrate an electrophysiological basis for low-frequency transcranial ultrasound stimulation of cerebral cortical neuronal activity.

  20. Four-gated transcranial Doppler ultrasound in the detection of circulating microemboli

    Microsoft Academic Search

    Dirk W. Droste; Ralf Dittrich; Stefan Hermes; Vendel Kemény; Gernot Schulte-Altedorneburg; Tjark Hansberg; E. Bernd Ringelstein

    1999-01-01

    Objective: Embolus detection by transcranial Doppler ultrasound is very time consuming and semi-automated detection is mandatory. The device studied, a TC4040, Nicolet-EME, uses the four-gate technique and allows for audiovisual off-line verification of the recorded events. Methods: Twenty controls, 10 patients with mechanical prosthetic heart valves and 12 patients with occlusive carotid artery disease were investigated by transcranial colour-coded duplex

  1. Dating the Seafloor with Unprecedented Resolution Using Geomagnetic Intensity Variations: Initial Results from Deep-Sea Three Components Magnetic Records Onboard a Submersible on the Central Indian Ridge, 19° S

    NASA Astrophysics Data System (ADS)

    Kitazawa, M.; Dyment, J.; Tamaki, K.

    2002-12-01

    The records of geomagnetic field paleointensity derived from sediment cores show the occurrence of short-lived magnetic low field intensity feature associated to excursions. If the oceanic crust is a good recorder of the magnetic intensity variation, these variations could be used to date the seafloor with an unprecedented resolution. To test this hypothesis on a slow to intermediate ridge, two high-resolution magnetic profiles were collected with a Deep-Sea Three Components Magnetometer (DSTCM) onboard submersible Nautile across the Central Indian Ridge (CIR) at 19° S. The CIR at the survey area is characterized by a spreading rate of about 4.3 km/yr (full rate), moderate topography roughness and a regular abyssal hills pattern. As the DSTCM was placed onboard the submersible, the magnetic field was measured at about 1 to 10 m above the seafloor. The profiles, each made of 8-9 dives, extend over the whole Brunhes period and reach the Brunhes-Matuyama boundaries on both ridge flanks. The recorded magnetic field was corrected for the main field and submersible magnetic effects. Synthetic magnetic anomalies and magnetic intensity were calculated assuming the real topography and dive path. Correlation of this synthetics and the observations on sliding windows 256 m-wide provide a direct estimate of the absolute magnetization intensity along the profiles. We present results obtained for the Northern profile. The profile of the magnetization intensity variation was compared to the record of the magnetic field paleointensity obtained from the sedimentary records. Main magnetic events such as Laschamps, Blake, Delta were recognized on the Eastern and Western flanks from the deep sea magnetic intensity profile. The consistency of the magnetic intensity variations obtained by DSTCM and sediment cores suggests that the oceanic crust in the survey area is a good recorder of the magnetic field variation at a resolution of 10 to 100 ky. The comparison of the magnetic intensity for both flanks of the CIR suggests that the spreading at the CIR at 19° S is highly symmetric, with maximum differences of 2 to 5 % between conjugate flanks.

  2. Transcranial direct current stimulation (tDCS) and language

    PubMed Central

    Monti, Alessia; Ferrucci, Roberta; Fumagalli, Manuela; Mameli, Francesca; Cogiamanian, Filippo; Ardolino, Gianluca; Priori, Alberto

    2013-01-01

    Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique inducing prolonged brain excitability changes and promoting cerebral plasticity, is a promising option for neurorehabilitation. Here, we review progress in research on tDCS and language functions and on the potential role of tDCS in the treatment of post-stroke aphasia. Currently available data suggest that tDCS over language-related brain areas can modulate linguistic abilities in healthy individuals and can improve language performance in patients with aphasia. Whether the results obtained in experimental conditions are functionally important for the quality of life of patients and their caregivers remains unclear. Despite the fact that important variables are yet to be determined, tDCS combined with rehabilitation techniques seems a promising therapeutic option for aphasia. PMID:23138766

  3. Transcranial Optical Monitoring of Cerebrovascular Hemodynamics in Acute Stroke Patients

    PubMed Central

    Durduran, Turgut; Zhou, Chao; Edlow, Brian L; Yu, Guoqiang; Choe, Regine; Kim, Meeri N; Cucchiara, Brett L; Putt, Mary E; Shah, Qaisar; Kasner, Scott E; Greenberg, Joel H; Yodh, Arjun G; Detre, John A

    2009-01-01

    “Diffuse correlation spectroscopy” (DCS) is a technology for non-invasive transcranial measurement of cerebral blood flow (CBF) that can be hybridized with “near-infrared spectroscopy” (NIRS). Taken together these methods hold potential for monitoring hemodynamics in stroke patients. We explore the utility of DCS and NIRS to measure effects of head-of-bed (HOB) positioning at 30°, 15°, 0°, ?5° and 0° angles in patients with acute ischemic stroke affecting frontal cortex and in controls. HOB positioning significantly altered CBF, oxy-hemoglobin (HbO2) and total-hemoglobin (THC) concentrations. Moreover, the presence of an ipsilateral infarct was a significant effect for all parameters. Results are consistent with the notion of impaired CBF autoregulation in the infarcted hemisphere. PMID:19259230

  4. Transcranial Doppler: an introduction for primary care physicians.

    PubMed

    Kassab, Mounzer Y; Majid, Arshad; Farooq, Muhammad U; Azhary, Hend; Hershey, Linda A; Bednarczyk, Edward M; Graybeal, Dion F; Johnson, Mark D

    2007-01-01

    Transcranial Doppler (TCD) is a diagnostic tool that can be used at bedside to assess the cerebral vasculature noninvasively. It is inexpensive, safe, and reliable when compared with other techniques. It can be repeated multiple times and can be used for continuous monitoring if needed. Screening of children with sickle cell disease to assess and prevent ischemic strokes and monitoring for vasospasm after subarachnoid hemorrhage are well established, evidenced based utilizations of TCD. It is useful for the evaluation of occlusive intracranial vascular lesions with many emerging indications in the management of ischemic stroke. TCD with micro-bubble enhancement has comparable sensitivity to transesophageal echocardiogram in detecting right-to-left atrial cardiac shunts. TCD is underused as a clinical tool despite well established indications. The pressure to contain increasing medical cost will likely result in increased utilization of this test in future. PMID:17204737

  5. Gender Differences in Current Received during Transcranial Electrical Stimulation

    PubMed Central

    Russell, Michael; Goodman, Theodore; Wang, Qiang; Groshong, Bennett; Lyeth, Bruce G.

    2014-01-01

    Low current transcranial electrical stimulation (tCS) is an effective but somewhat inconsistent tool for augmenting neuromodulation. In this study, we used 3D MRI guided electrical transcranial stimulation modeling to estimate the range of current intensities received at cortical brain tissues. Combined T1, T2, and proton density MRIs from 24 adult subjects (12 male and 12 female) were modeled with virtual electrodes placed at F3, F4, C3, and C4. Two sizes of electrodes 20?mm round and 50?mm?×?45?mm were examined at 0.5, 1, and 2?mA input currents. The intensity of current received was sampled in a 1-cm sphere placed at the cortex directly under each scalp electrode. There was a 10-fold difference in the amount of current received by individuals. A large gender difference was observed with female subjects receiving significantly less current at targeted parietal cortex than male subjects when stimulated at identical current levels (P?

  6. Direct transcranial puncture for Onyx embolization of a cerebellar hemangioblastoma.

    PubMed

    Ding, Dale; Starke, Robert M; Evans, Avery J; Liu, Kenneth C

    2014-06-01

    Intracranial hemangioblastomas are benign but hypervascular tumors, most commonly located in the cerebellum, which are difficult to resect without significant operative blood loss. While preoperative embolization may decrease the amount of operative bleeding, the vascular supply of cerebellar hemangioblastomas frequently precludes safe embolization by an endovascular route due to the risk of thromboembolic vertebrobasilar infarction. Direct puncture embolization overcomes many of the limitations of endovascular embolization but its safety and feasibility for intracranial tumors is unknown. We report a 48-year-old man who was diagnosed with a large cerebellar mass after presenting with headaches and gait ataxia. Based on diagnostic angiography, which demonstrated a highly vascular tumor supplied by the posterior inferior cerebellar and posterior meningeal arteries, we decided to embolize the tumor by a direct transcranial puncture approach. After trephinating the skull in a standard fashion, a catheter-needle construct, composed of an Echelon 10 microcatheter (ev3 Endovascular, Plymouth, MN, USA) placed into a 21-gauge spinal needle, was inserted into the tumor under biplanar angiographic guidance. Using continuous angiographic monitoring, 9cc of Onyx 34 (ev3 Endovascular) was injected through the catheter, resulting in 75% tumor devascularization without evidence of complications. The patient was taken directly to surgery where a gross total resection of the hemangioblastoma was achieved with an acceptable operative blood loss. At his 2 year follow-up, the patient was neurologically intact without neuroimaging evidence of residual tumor. We describe, to our knowledge, the first case of direct transcranial puncture for preoperative embolization of a cerebellar hemangioblastoma. PMID:24370504

  7. Prehospital stroke diagnostics based on neurological examination and transcranial ultrasound

    PubMed Central

    2014-01-01

    Background Transcranial color-coded sonography (TCCS) has proved to be a fast and reliable tool for the detection of middle cerebral artery (MCA) occlusions in a hospital setting. In this feasibility study on prehospital sonography, our aim was to investigate the accuracy of TCCS for neurovascular emergency diagnostics when performed in a prehospital setting using mobile ultrasound equipment as part of a neurological examination. Methods Following a ‘911 stroke code’ call, stroke neurologists experienced in TCCS rendezvoused with the paramedic team. In patients with suspected stroke, TCCS examination including ultrasound contrast agents was performed. Results were compared with neurovascular imaging (CTA, MRA) and the final discharge diagnosis from standard patient-centered stroke care. Results We enrolled ‘232 stroke code’ patients with follow-up data available in 102 patients with complete TCCS examination. A diagnosis of ischemic stroke was made in 73 cases; 29 patients were identified as ‘stroke mimics’. MCA occlusion was diagnosed in ten patients, while internal carotid artery (ICA) occlusion/high-grade stenosis leading to reversal of anterior cerebral artery flow was diagnosed in four patients. The initial working diagnosis ‘any stroke’ showed a sensitivity of 94% and a specificity of 48%. ‘Major MCA or ICA stroke’ diagnosed by mobile ultrasound showed an overall sensitivity of 78% and specificity of 98%. Conclusions The study demonstrates the feasibility and high diagnostic accuracy of emergency transcranial ultrasound assessment combined with neurological examinations for major ischemic stroke. Future combination with telemedical support, point-of-care analysis of blood serum markers, and probability algorithms of prehospital stroke diagnosis including ultrasound may help to speed up stroke treatment. PMID:24572006

  8. 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)

    Sun, Bin; Wang, Liangshu; Dong, Ping; Wu, YongJing; Li, Changbo; Hu, Bo; Wang, Chong

    2012-11-01

    The Hailar Basin is one of the typical basins among the NE China Basin Groups, 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 magnetic, gravity, petrophysical, geothermal and seismological data, we separate the Gravity and Magnetic Anomalies (GMA) into four orders using Wavelet Multi-scale Decomposition (WMD). The apparent depths of causative sources were then assessed by Power Spectrum Analysis (PSA) of each order. Low-order wavelet detail anomalies were used to study the basin's basement structure such as major faults, the basement lithology, uplifts and depressions. High-order ones were used for the inversion of Moho and Curie discontinuities using the Parker method. The results show that the Moho uplifting area of the Hailar Basin is located at the NE part of the basin, the Curie uplifting area is at the NW part, and neither of them is consistent with the basin's sedimentary center. This indicates that the Hailar Basin may differ in basin building pattern from other middle and eastern basins of the basin groups, and the Hailar Basin might be of a passive type. When the Pacific Plate was subducting to NE China, the frontier of the plate lying on the mantle transition zone didn't pass through the Great Khingan Mountains region, so there is not an obvious magma upwelling or lithospheric extension in the Hailar Basin area. Finally, based on the seismological data and results of WMD, a probable 2D crust model is derived from an across-basin profile using the 2D forward modeling of the Bouguer gravity anomaly. The results agree with those from seismic inversion, suggesting WMD is suitable for identifying major crustal density interfaces.

  9. Anodal transcranial direct current stimulation temporarily reverses age-associated cognitive decline and functional brain activity changes.

    PubMed

    Meinzer, Marcus; Lindenberg, Robert; Antonenko, Daria; Flaisch, Tobias; Flöel, Agnes

    2013-07-24

    The rising proportion of elderly people worldwide will yield an increased incidence of age-associated cognitive impairments, imposing major burdens on societies. Consequently, growing interest emerged to evaluate new strategies to delay or counteract cognitive decline in aging. Here, we assessed immediate effects of anodal transcranial direct current stimulation (atDCS) on cognition and previously described detrimental changes in brain activity attributable to aging. Twenty healthy elderly adults were assessed in a crossover sham-controlled design using functional magnetic resonance imaging (fMRI) and concurrent transcranial DCS administered to the left inferior frontal gyrus. Effects on performance and task-related brain activity were evaluated during overt semantic word generation, a task that is negatively affected by advanced age. Task-absent resting-state fMRI (RS-fMRI) assessed atDCS-induced changes at the network level independent of performance. Twenty matched younger adults served as controls. During sham stimulation, task-related fMRI demonstrated that enhanced bilateral prefrontal activity in older adults was associated with reduced performance. RS-fMRI revealed enhanced anterior and reduced posterior functional brain connectivity. atDCS significantly improved performance in older adults up to the level of younger controls; significantly reduced task-related hyperactivity in bilateral prefrontal cortices, the anterior cingulate gyrus, and the precuneus; and induced a more "youth-like" connectivity pattern during RS-fMRI. Our results provide converging evidence from behavioral analysis and two independent functional imaging paradigms that a single session of atDCS can temporarily reverse nonbeneficial effects of aging on cognition and brain activity and connectivity. These findings may translate into novel treatments to ameliorate cognitive decline in normal aging in the future. PMID:23884951

  10. Effects of anodal transcranial direct current stimulation over the leg motor area on lumbar spinal network excitability in healthy subjects

    PubMed Central

    Roche, N; Lackmy, A; Achache, V; Bussel, B; Katz, R

    2011-01-01

    Abstract In recent years, two techniques have become available for the non-invasive stimulation of human motor cortex: transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). The effects of TMS and tDCS when applied over motor cortex should be considered with regard not only to cortical circuits but also to spinal motor circuits. The different modes of action and specificity of TMS and tDCS suggest that their effects on spinal network excitability may be different from that in the cortex. Until now, the effects of tDCS on lumbar spinal network excitability have never been studied. In this series of experiments, on healthy subjects, we studied the effects of anodal tDCS over the lower limb motor cortex on (i) reciprocal Ia inhibition projecting from the tibialis anterior muscle (TA) to the soleus (SOL), (ii) presynaptic inhibition of SOL Ia terminals, (iii) homonymous SOL recurrent inhibition, and (iv) SOL H-reflex recruitment curves. The results show that anodal tDCS decreases reciprocal Ia inhibition, increases recurrent inhibition and induces no modification of presynaptic inhibition of SOL Ia terminals and of SOL-H reflex recruitment curves. Our results indicate therefore that the effects of tDCS are the opposite of those previously described for TMS on spinal network excitability. They also indicate that anodal tDCS induces effects on spinal network excitability similar to those observed during co-contraction suggesting that anodal tDCS activates descending corticospinal projections mainly involved in co-contractions. PMID:21502292

  11. Anodal transcranial direct current stimulation to the cerebellum improves handwriting and cyclic drawing kinematics in focal hand dystonia

    PubMed Central

    Bradnam, Lynley V.; Graetz, Lynton J.; McDonnell, Michelle N.; Ridding, Michael C.

    2015-01-01

    There is increasing evidence that the cerebellum has a role in the pathophysiology of primary focal hand dystonia and might provide an intervention target for non-invasive brain stimulation to improve function of the affected hand. The primary objective of this study was to determine if cerebellar transcranial direct current stimulation (tDCS) improves handwriting and cyclic drawing kinematics in people with hand dystonia, by reducing cerebellar-brain inhibition (CBI) evoked by transcranial magnetic stimulation (TMS). Eight people with dystonia (5 writer’s dystonia, 3 musician’s dystonia) and eight age-matched controls completed the study and underwent cerebellar anodal, cathodal and sham tDCS in separate sessions. Dystonia severity was assessed using the Writer’s Cramp Rating Scale (WRCS) and the Arm Dystonia Disability Scale (ADDS). The kinematic measures that differentiated the groups were; mean stroke frequency during handwriting and fast cyclic drawing and average pen pressure during light cyclic drawing. TMS measures of cortical excitability were no different between people with FHD and controls. There was a moderate, negative relationship between TMS-evoked CBI at baseline and the WRCS in dystonia. Anodal cerebellar tDCS reduced handwriting mean stroke frequency and average pen pressure, and increased speed and reduced pen pressure during fast cyclic drawing. Kinematic measures were not associated with a decrease in CBI within an individual. In conclusion, cerebellar anodal tDCS appeared to improve kinematics of handwriting and circle drawing tasks; but the underlying neurophysiological mechanism remains uncertain. A study in a larger homogeneous population is needed to further investigate the possible therapeutic benefit of cerebellar tDCS in dystonia. PMID:26042019

  12. Anodal transcranial direct current stimulation to the cerebellum improves handwriting and cyclic drawing kinematics in focal hand dystonia.

    PubMed

    Bradnam, Lynley V; Graetz, Lynton J; McDonnell, Michelle N; Ridding, Michael C

    2015-01-01

    There is increasing evidence that the cerebellum has a role in the pathophysiology of primary focal hand dystonia and might provide an intervention target for non-invasive brain stimulation to improve function of the affected hand. The primary objective of this study was to determine if cerebellar transcranial direct current stimulation (tDCS) improves handwriting and cyclic drawing kinematics in people with hand dystonia, by reducing cerebellar-brain inhibition (CBI) evoked by transcranial magnetic stimulation (TMS). Eight people with dystonia (5 writer's dystonia, 3 musician's dystonia) and eight age-matched controls completed the study and underwent cerebellar anodal, cathodal and sham tDCS in separate sessions. Dystonia severity was assessed using the Writer's Cramp Rating Scale (WRCS) and the Arm Dystonia Disability Scale (ADDS). The kinematic measures that differentiated the groups were; mean stroke frequency during handwriting and fast cyclic drawing and average pen pressure during light cyclic drawing. TMS measures of cortical excitability were no different between people with FHD and controls. There was a moderate, negative relationship between TMS-evoked CBI at baseline and the WRCS in dystonia. Anodal cerebellar tDCS reduced handwriting mean stroke frequency and average pen pressure, and increased speed and reduced pen pressure during fast cyclic drawing. Kinematic measures were not associated with a decrease in CBI within an individual. In conclusion, cerebellar anodal tDCS appeared to improve kinematics of handwriting and circle drawing tasks; but the underlying neurophysiological mechanism remains uncertain. A study in a larger homogeneous population is needed to further investigate the possible therapeutic benefit of cerebellar tDCS in dystonia. PMID:26042019

  13. Magnetism

    NSDL National Science Digital Library

    University Corporation for Atmospheric Research Windows to the Universe team

    2007-12-12

    This webpage is part of the University Corporation for Atmospheric Research (UCAR) Windows to the Universe program. It describes the nature and configuration of magnetic fields, which are the result of moving electric charges, including how they cause magnetic objects to orient themselves along the direction of the magnetic force points, which are illustrated as lines. Magnetic field lines by convention point outwards at the north magnetic pole and inward at the south magnetic pole. The site features text, scientific illustrations and an animation. Text and vocabulary are selectable for the beginning, intermediate, or advanced reader.

  14. Deep Web Web Deep Web Web

    E-print Network

    Deep Web 100872 Deep Web Web Deep Web Web Web Deep Web Deep Web TP391 A Uncertain Schema Matching in Deep Web Integration Service JIANG Fang-Jiao MENG Xiao-Feng JIA Lin-Lin (School of Information, Renmin University of China, Beijing, 100872) Abstract: With increasing of Deep Web, providing

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

    E-print Network

    Besio, Walter G.

    (RNS) [9], [10], vagus nerve stimulation (VNS) [11]­[15], and trigem- inal nerve stimulation (TNS) [16 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

  16. tDCS and Flexible Tool Use 1 Noninvasive Transcranial Direct Current Stimulation Over the Left Prefrontal Cortex

    E-print Network

    Thompson-Schill, Sharon

    tDCS and Flexible Tool Use 1 Noninvasive Transcranial Direct Current Stimulation Over the Left (inhibitory) transcranial direct current stimulation (tDCS) will facilitate performance in a flexible use or an uncommon use for it, while receiving cathodal tDCS (1.5 mA) either over left or right PFC, or sham

  17. Prefrontal control during a semantic decision task that involves idiom comprehension: A transcranial direct current stimulation study

    E-print Network

    Ivry, Rich

    Cognitive control tDCS DLPFC Trait motivation Idioms a b s t r a c t Language processing and comprehension, we used transcranial direct current stimulation (tDCS) to test the hypotheses that (I) a prefrontal stimulation technique, transcranial direct current stimu- lation (tDCS). tDCS is a painless cortical

  18. Real-Time 3D Contrast-Enhanced Transcranial Ultrasound and Aberration Correction

    PubMed Central

    Ivancevich, Nikolas M.; Pinton, Gianmarco F.; Nicoletto, Heather A.; Bennett, Ellen; Laskowitz, Daniel T.; Smith, Stephen W.

    2008-01-01

    Contrast-enhanced (CE) transcranial ultrasound (US) and reconstructed 3D transcranial ultrasound have shown advantages over traditional methods in a variety of cerebrovascular diseases. We present the results from a novel ultrasound technique, namely real-time 3D contrast-enhanced transcranial ultrasound. Using real-time 3D (RT3D) ultrasound and micro-bubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and 9 via the sub-occipital window and report our detection rates for the major cerebral vessels. In 71% of subjects, both of our observers identified the ipsilateral circle of Willis from the temporal window, and in 59% we imaged the entire circle of Willis. From the sub-occipital window, both observers detected the entire vertebrobasilar circulation in 22% of subjects, and in 44% the basilar artery. After performing phase aberration correction on one subject, we were able to increase the diagnostic value of the scan, detecting a vessel not present in the uncorrected scan. These preliminary results suggest that RT3D CE transcranial US and RT3D CE transcranial US with phase aberration correction have the potential to greatly impact the field of neurosonology. PMID:18395321

  19. Cerebral vasospasm after subarachnoid haemorrhage of unknown aetiology: a clinical and transcranial Doppler study.

    PubMed

    Schaller, C; Raueiser, B; Rohde, V; Hassler, W

    1996-01-01

    Sixteen patients (6 women, 10 men; mean age: 52.5 years) suffering from spontaneous subarachnoid haemorrhage (SAH) of unknown origin underwent a protocol of initial and then weekly computed tomography (CT), initial four-vessel digital subtraction angiography (DSA) and at least one control pancerebral DSA. Fourteen patients had magnetic resonance imaging before undergoing first control DSA. All patients had calcium-antagonists (Nimodipine) via a central venous catheter, were kept on the neurosurgical intensive care unit and followed daily with transcranial Doppler ultrasonography (TCD). One patient (6.3%) developed moderate and 5 (31.1%) developed severe cerebral vasospasm as documented with TCD and exhibited deterioration of their level of consciousness. These 6 patients were treated with induced hypertension, hypervolaemia and haemodilution. Their blood flow velocities were elevated for a mean of 8 (5-17) days with a peak after 12.5 (9-17) days following SAH. No complications due to treatment were noted. One patient of the non-vasospastic group died of pulmonary embolism, another patient had an ischaemic incident during angiography, which has led to permanent disability. On follow-up 2-24 months after SAH 14 patients had returned to their premorbid state. It is concluded that patients suffering from SAH of unknown origin should undergo repeated angiographic investigation and subsequent daily monitoring of their neurologic status including daily TCD recordings so that haemodynamic treatment can be established in the event of cerebral vasospasm, which may occur in up to one third of these patients. PMID:8800332

  20. The optimal velocity criterion in the diagnosis of unilateral middle cerebral artery stenosis by transcranial Doppler.

    PubMed

    Chen, Jiafeng; Wang, Lin; Bai, Jing; Lun, Zhijun; Zhang, Jinqiao; Xing, Yingqi

    2014-05-01

    We evaluated the optimal flow velocity of transcranial doppler (TCD) in detecting unilateral middle cerebral artery (MCA) stenosis and stenosis grading by magnetic resonance angiography (MRA) as the reference standard. 302 nonconsecutive patients with unilateral MCA stenosis detected by TCD underwent MRA of the intracranial arteries. The peak systolic velocity (PSV), mean flow velocity (MFV), and end-diastolic velocity (EDV) of each MCA were recorded. 604 MCA were categorized into four groups depending on the stenosis severity: normal MCA (n = 319, 52.8%), mild stenosis (n = 94, 15.6%), moderate stenosis (n = 66, 10.9%), and severe stenosis (n = 125, 20.7%). Significant differences in PSV, MFV, and EDV between these four groups were observed (P < 0.001, respectively). The optimal cutoff velocities for detecting MCA stenosis were: PSV = 160 cm/s, MFV = 100 cm/s, EDV = 60 cm/s; the optimal cutoff points to distinguish mild from moderate stenosis were: PSV = 200 cm/s, MFV = 120 cm/s, EDV = 80 cm/s; the cutoffs to distinguish moderate from severe stenosis were: PSV = 280 cm/s, MFV = 180 cm/s, EDV = 110 cm/s. Using PSV as the diagnostic criteria, the correlation for diagnosing MCA stenosis using TCD and MCA was good (Kappa number ? = 0.668); using as MFV criteria, ? = 0.641. The optimal cutoff PSV values in stenosis grading on TCD were 160, 200, and 280 cm/s. The optimal cutoff MFV values were 100, 120, and 180 cm/s. PSV is more accurate than MFV in detecting and grading MCA stenosis. PMID:24146392

  1. Polarity-specific transcranial direct current stimulation disrupts auditory pitch learning.

    PubMed

    Matsushita, Reiko; Andoh, Jamila; Zatorre, Robert J

    2015-01-01

    Transcranial direct current stimulation (tDCS) is attracting increasing interest because of its potential for therapeutic use. While its effects have been investigated mainly with motor and visual tasks, less is known in the auditory domain. Past tDCS studies with auditory tasks demonstrated various behavioral outcomes, possibly due to differences in stimulation parameters, task-induced brain activity, or task measurements used in each study. Further research, using well-validated tasks is therefore required for clarification of behavioral effects of tDCS on the auditory system. Here, we took advantage of findings from a prior functional magnetic resonance imaging study, which demonstrated that the right auditory cortex is modulated during fine-grained pitch learning of microtonal melodic patterns. Targeting the right auditory cortex with tDCS using this same task thus allowed us to test the hypothesis that this region is causally involved in pitch learning. Participants in the current study were trained for 3 days while we measured pitch discrimination thresholds using microtonal melodies on each day using a psychophysical staircase procedure. We administered anodal, cathodal, or sham tDCS to three groups of participants over the right auditory cortex on the second day of training during performance of the task. Both the sham and the cathodal groups showed the expected significant learning effect (decreased pitch threshold) over the 3 days of training; in contrast we observed a blocking effect of anodal tDCS on auditory pitch learning, such that this group showed no significant change in thresholds over the 3 days. The results support a causal role for the right auditory cortex in pitch discrimination learning. PMID:26041982

  2. Polarity-specific transcranial direct current stimulation disrupts auditory pitch learning

    PubMed Central

    Matsushita, Reiko; Andoh, Jamila; Zatorre, Robert J.

    2015-01-01

    Transcranial direct current stimulation (tDCS) is attracting increasing interest because of its potential for therapeutic use. While its effects have been investigated mainly with motor and visual tasks, less is known in the auditory domain. Past tDCS studies with auditory tasks demonstrated various behavioral outcomes, possibly due to differences in stimulation parameters, task-induced brain activity, or task measurements used in each study. Further research, using well-validated tasks is therefore required for clarification of behavioral effects of tDCS on the auditory system. Here, we took advantage of findings from a prior functional magnetic resonance imaging study, which demonstrated that the right auditory cortex is modulated during fine-grained pitch learning of microtonal melodic patterns. Targeting the right auditory cortex with tDCS using this same task thus allowed us to test the hypothesis that this region is causally involved in pitch learning. Participants in the current study were trained for 3 days while we measured pitch discrimination thresholds using microtonal melodies on each day using a psychophysical staircase procedure. We administered anodal, cathodal, or sham tDCS to three groups of participants over the right auditory cortex on the second day of training during performance of the task. Both the sham and the cathodal groups showed the expected significant learning effect (decreased pitch threshold) over the 3 days of training; in contrast we observed a blocking effect of anodal tDCS on auditory pitch learning, such that this group showed no significant change in thresholds over the 3 days. The results support a causal role for the right auditory cortex in pitch discrimination learning.

  3. Magnetic stimulation study in patients with myotonic dystrophy

    Microsoft Academic Search

    M Oliveri; F Brighina; V La Bua; A Aloisio; D Buffa; B Fierro

    1997-01-01

    To further define motor nervous system alterations in myotonic dystrophy (MD), motor potentials to transcranial and cervical magnetic stimulation (MEPs) were recorded from the right abductor pollicis brevis muscle in 10 patients with MD and in 10 healthy controls. Cortical and cervical latencies, central motor conduction time (CMCT), stimulus threshold intensity and cortical MEP amplitudes expressed both as absolute values

  4. TRANSCRANIAL AMELIORATION OF INFLAMMATION AND CELL DEATH FOLLOWING BRAIN INJURY

    PubMed Central

    Roth, Theodore L.; Nayak, Debasis; Atanasijevic, Tatjana; Koretsky, Alan P.; Latour, Lawrence L.; McGavern, Dorian B.

    2014-01-01

    Traumatic brain injury (TBI) is increasingly appreciated to be highly prevalent and deleterious to neurological function 1, 2. At present no effective treatment options are available, and little is known about the complex cellular response to TBI during its acute phase. To gain novel insights into TBI pathogenesis, we developed a novel closed-skull brain injury model that mirrors some pathological features associated with mild TBI in humans and used long-term intravital microscopy to study the dynamics of the injury response from its inception. Here we demonstrate that acute brain injury induces vascular damage, meningeal cell death, and the generation of reactive oxygen species (ROS) that ultimately breach the glial limitans and promote spread of the injury into the parenchyma. In response, the brain elicits a neuroprotective, purinergic receptor dependent inflammatory response characterized by meningeal neutrophil swarming and microglial reconstitution of the damaged glial limitans. We additionally show that the skull bone is permeable to small molecular weight compounds and use this delivery route to modulate inflammation and therapeutically ameliorate brain injury through transcranial administration of the ROS scavenger, glutathione. Our results provide novel insights into the acute cellular response to TBI and a means to locally deliver therapeutic compounds to the site of injury. PMID:24317693

  5. Transcranial ultrasound in neurodegeneration with brain iron accumulation (NBIA).

    PubMed

    Liman, Jan; Wellmer, Andreas; Rostasy, Kevin; Bähr, Mathias; Kermer, Pawel

    2012-03-01

    NBIA/HSS is a neurodegenerative disorder associated with iron accumulation in specific brain regions. To date, the diagnosis is obtained by typical MRI changes followed by genetic mutation analysis. This procedure is laborious and limited to a few specially equipped medical centres. Since transcranial sonography (TCS) is widely used for the early diagnosis of PD in adults displaying parenchymal metal deposits, it is likely to be a reliable diagnostic tool for the early diagnosis of NBIA. In 7 patients with proven NBIA and 13 age-matched controls without record of neurological disease TCS was performed by an experienced ultrasound examiner. Data were analysed by two blinded investigators regarding hyperechogenicity and size of the substantia nigra (SN). SN size and hyperechogenicity was significantly increased in patients with NBIA compared to controls (students t-test: p < 0.001). TCS appears to be a non-invasive and inexpensive screening technique in patients with suspected NBIA. Performed by an experienced physician, it could enable an earlier diagnosis and pre-selection of patients for the MRI scan and genetic testing, which are still the diagnostic gold standard. PMID:21816641

  6. Transcranial direct current stimulation as a treatment for auditory hallucinations.

    PubMed

    Koops, Sanne; van den Brink, Hilde; Sommer, Iris E C

    2015-01-01

    Auditory hallucinations (AH) are a symptom of several psychiatric disorders, such as schizophrenia. In a significant minority of patients, AH are resistant to antipsychotic medication. Alternative treatment options for this medication resistant group are scarce and most of them focus on coping with the hallucinations. Finding an alternative treatment that can diminish AH is of great importance. Transcranial direct current stimulation (tDCS) is a safe and non-invasive technique that is able to directly influence cortical excitability through the application of very low electric currents. A 1-2 mA direct current is applied between two surface electrodes, one serving as the anode and the other as the cathode. Cortical excitability is increased in the vicinity of the anode and reduced near the cathode. The technique, which has only a few transient side effects and is cheap and portable, is increasingly explored as a treatment for neurological and psychiatric symptoms. It has shown efficacy on symptoms of depression, bipolar disorder, schizophrenia, Alzheimer's disease, Parkinson's disease, epilepsy, and stroke. However, the application of tDCS as a treatment for AH is relatively new. This article provides an overview of the current knowledge in this field and guidelines for future research. PMID:25798123

  7. Cerebellar Transcranial Direct Current Stimulation Effects on Saccade Adaptation

    PubMed Central

    van der Geest, Jos N.; Kengne Kamga, Sandra; Verhage, M. Claire; Donchin, Opher; Frens, Maarten A.

    2015-01-01

    Saccade adaptation is a cerebellar-mediated type of motor learning in which the oculomotor system is exposed to repetitive errors. Different types of saccade adaptations are thought to involve distinct underlying cerebellar mechanisms. Transcranial direct current stimulation (tDCS) induces changes in neuronal excitability in a polarity-specific manner and offers a modulatory, noninvasive, functional insight into the learning aspects of different brain regions. We aimed to modulate the cerebellar influence on saccade gains during adaptation using tDCS. Subjects performed an inward (n = 10) or outward (n = 10) saccade adaptation experiment (25% intrasaccadic target step) while receiving 1.5?mA of anodal cerebellar tDCS delivered by a small contact electrode. Compared to sham stimulation, tDCS increased learning of saccadic inward adaptation but did not affect learning of outward adaptation. This may imply that plasticity mechanisms in the cerebellum are different between inward and outward adaptation. TDCS could have influenced specific cerebellar areas that contribute to inward but not outward adaptation. We conclude that tDCS can be used as a neuromodulatory technique to alter cerebellar oculomotor output, arguably by engaging wider cerebellar areas and increasing the available resources for learning. PMID:25821604

  8. Transcranial Doppler and rCBF compared in carotid endarterectomy

    SciTech Connect

    Halsey, J.H.; McDowell, H.A.; Gelman, S.

    1986-11-01

    In eight patients undergoing carotid endarterectomy, the mean velocity and an index of pulse amplitude in the middle cerebral artery were monitored continuously by transcranial doppler ultrasound. rCBF was measured by intracarotid injection of 133 Xenon shortly before and at the time of the carotid artery occlusion, and again a few minutes after carotid flow was reestablished. Comparison of the mean velocity in the MCA and the cortical convexity rCBF revealed relatively little hysteresis in their relationship from prior to after the occlusion. There was however, considerable variability in this relationship among patients. Both the rCBF and the velocity decreased substantially at occlusion in three cases, neither changed very much in three. While in two, though the rCBF decreased significantly, the velocity did not change. The index of pulse amplitude was somewhat more sensitive to the occlusion, decreasing in the seven cases in which it was recorded, including one in which the rCBF did not change.

  9. Improving Myoelectric Control for Amputees through Transcranial Direct Current Stimulation.

    PubMed

    Pan, Lizhi; Zhang, Dingguo; Sheng, Xinjun; Zhu, Xiangyang

    2015-08-01

    Most prosthetic myoelectric control studies have shown good performance for unimpaired subjects. However, performance is generally unacceptable for amputees. The primary problem is the poor quality of electromyography (EMG) signals of amputees compared with healthy individuals. To improve clinical performance of myoelectric control, this study explored transcranial direct current stimulation (tDCS) to modulate brain activity and enhance EMG quality. We tested six unilateral transradial amputees by applying active and sham anodal tDCS separately on two different days. Surface EMG signals were acquired from the affected and intact sides for 11 hand and wrist motions in the pre-tDCS and post-tDCS sessions. Autoregression coefficients and linear discriminant analysis classifiers were used to process the EMG data for pattern recognition of the 11 motions. For the affected side, active anodal tDCS significantly reduced the average classification error rate (CER) by 10.1%, while sham tDCS had no such effect. For the intact side, the average CER did not change on the day of sham tDCS but increased on the day of active tDCS. These results demonstrated that tDCS could modulate brain function and improve EMG-based classification performance for amputees. It has great potential in dramatically reducing the length of learning process of amputees for effectively using myoelectrically controlled multifunctional prostheses. PMID:25730820

  10. Electrode Positioning and Montage in Transcranial Direct Current Stimulation

    PubMed Central

    DaSilva, Alexandre F.; Volz, Magdalena Sarah; Bikson, Marom; Fregni, Felipe

    2011-01-01

    Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a non-invasive and safe alternative to change cortical excitability2. The effects of one session of tDCS can last for several minutes, and its effects depend on polarity of stimulation, such as that cathodal stimulation induces a decrease in cortical excitability, and anodal stimulation induces an increase in cortical excitability that may last beyond the duration of stimulation6. These effects have been explored in cognitive neuroscience and also clinically in a variety of neuropsychiatric disorders – especially when applied over several consecutive sessions4. One area that has been attracting attention of neuroscientists and clinicians is the use of tDCS for modulation of pain-related neural networks3,5. Modulation of two main cortical areas in pain research has been explored: primary motor cortex and dorsolateral prefrontal cortex7. Due to the critical role of electrode montage, in this article, we show different alternatives for electrode placement for tDCS clinical trials on pain; discussing advantages and disadvantages of each method of stimulation. PMID:21654618

  11. Simulation and measurement of transcranial near infrared light penetration

    NASA Astrophysics Data System (ADS)

    Yue, Lan; Monge, Manuel; Ozgur, Mehmet H.; Murphy, Kevin; Louie, Stan; Miller, Carol A.; Emami, Azita; Humayun, Mark S.

    2015-03-01

    We are studying the transmission of LED array-emitted near-infrared (NIR) light through human tissues. Herein, we simulated and measured transcranial NIR penetration in highly scattering human head tissues. Using finite element analysis, we simulated photon diffusion in a multilayered 3D human head model that consists of scalp, skull, cerebral spinal fluid, gray matter and white matter. The optical properties of each layer, namely scattering and absorption coefficient, correspond to the 850 nm NIR light. The geometry of the model is minimally modified from the IEEE standard and the multiple LED emitters in an array were evenly distributed on the scalp. Our results show that photon distribution produced by the array exhibits little variation at similar brain depth, suggesting that due to strong scattering effects of the tissues, discrete spatial arrangements of LED emitters in an array has the potential to create a quasi-radially symmetrical illumination field. Measurements on cadaveric human head tissues excised from occipital, parietal, frontal and temporal regions show that illumination with an 850 nm LED emitter rendered a photon flux that closely follows simulation results. In addition, prolonged illumination of LED emitted NIR showed minimal thermal effects on the brain.

  12. Neurobiological Effects of Transcranial Direct Current Stimulation: A Review

    PubMed Central

    Medeiros, Liciane Fernandes; de Souza, Izabel Cristina Custodio; Vidor, Liliane Pinto; de Souza, Andressa; Deitos, Alícia; Volz, Magdalena Sarah; Fregni, Felipe; Caumo, Wolnei; Torres, Iraci L. S.

    2012-01-01

    Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique that is affordable and easy to operate compared to other neuromodulation techniques. Anodal stimulation increases cortical excitability, while the cathodal stimulation decreases it. Although tDCS is a promising treatment approach for chronic pain as well as for neuropsychiatric diseases and other neurological disorders, several complex neurobiological mechanisms that are not well understood are involved in its effect. The purpose of this systematic review is to summarize the current knowledge regarding the neurobiological mechanisms involved in the effects of tDCS. The initial search resulted in 171 articles. After applying inclusion and exclusion criteria, we screened 32 full-text articles to extract findings about the neurobiology of tDCS effects including investigation of cortical excitability parameters. Overall, these findings show that tDCS involves a cascade of events at the cellular and molecular levels. Moreover, tDCS is associated with glutamatergic, GABAergic, dopaminergic, serotonergic, and cholinergic activity modulation. Though these studies provide important advancements toward the understanding of mechanisms underlying tDCS effects, further studies are needed to integrate these mechanisms as to optimize clinical development of tDCS. PMID:23293607

  13. Refraction Correction in 3D Transcranial Ultrasound Imaging

    PubMed Central

    Lindsey, Brooks D.; Smith, Stephen W.

    2014-01-01

    We present the first correction of refraction in three-dimensional (3D) ultrasound imaging using an iterative approach that traces propagation paths through a two-layer planar tissue model, applying Snell’s law in 3D. This approach is applied to real-time 3D transcranial ultrasound imaging by precomputing delays offline for several skull thicknesses, allowing the user to switch between three sets of delays for phased array imaging at the push of a button. Simulations indicate that refraction correction may be expected to increase sensitivity, reduce beam steering errors, and partially restore lost spatial resolution, with the greatest improvements occurring at the largest steering angles. Distorted images of cylindrical lesions were created by imaging through an acrylic plate in a tissue-mimicking phantom. As a result of correcting for refraction, lesions were restored to 93.6% of their original diameter in the lateral direction and 98.1% of their original shape along the long axis of the cylinders. In imaging two healthy volunteers, the mean brightness increased by 8.3% and showed no spatial dependency. PMID:24275538

  14. Transcranial direct current stimulation: electrode montage in stroke.

    PubMed

    Mahmoudi, Hooman; Borhani Haghighi, Afshin; Petramfar, Peyman; Jahanshahi, Sepehr; Salehi, Zahra; Fregni, Felipe

    2011-01-01

    Neurophysiological and computer modelling studies have shown that electrode montage is a critical parameter to determine the neuromodulatory effects of transcranial direct current stimulation (tDCS). We tested these results clinically by systematically investigating optimal tDCS electrode montage in stroke. Ten patients received in a counterbalanced and randomised order the following conditions of stimulation (i) anodal stimulation of affected M1 (primary motor cortex) and cathodal stimulation of unaffected M1 ('bilateral tDCS'); (ii) anodal stimulation of affected M1 and cathodal stimulation of contralateral supraorbital area ('anodal tDCS'); (iii) cathodal stimulation of unaffected M1 and anodal stimulation of contralateral supraorbital area ('cathodal tDCS'); (iv) anodal stimulation of affected M1 and cathodal stimulation of contralateral deltoid muscle ('extra-cephalic tDCS') and (v) sham stimulation. We used the Jebsen-Taylor Test (JTT) as a widely accepted measure of upper limb function. Bilateral tDCS, anodal tDCS and cathodal tDCS were shown to be associated with significant improvements on the JTT. Placing the reference electrode in an extracephalic position and use of sham stimulation did not induce any significant effects. This small sham controlled cross-over clinical trial is important to provide additional data on the clinical effects of tDCS in stroke and for planning and designing future large tDCS trials in patients with stroke. PMID:21110732

  15. Transcranial LED therapy for cognitive dysfunction in chronic, mild traumatic brain injury: two case reports

    NASA Astrophysics Data System (ADS)

    Naeser, Margaret A.; Saltmarche, Anita; Krengel, Maxine H.; Hamblin, Michael R.; Knight, Jeffrey A.

    2010-02-01

    Two chronic, traumatic brain injury (TBI) cases are presented, where cognitive function improved following treatment with transcranial light emitting diodes (LEDs). At age 59, P1 had closed-head injury from a motor vehicle accident (MVA) without loss of consciousness and normal MRI, but unable to return to work as development specialist in internet marketing, due to cognitive dysfunction. At 7 years post-MVA, she began transcranial LED treatments with cluster heads (2.1" diameter with 61 diodes each - 9x633nm, 52x870nm; 12-15mW per diode; total power, 500mW; 22.2 mW/cm2) on bilateral frontal, temporal, parietal, occipital and midline sagittal areas (13.3 J/cm2 at scalp, estimated 0.4 J/cm2 to brain cortex per area). Prior to transcranial LED, focused time on computer was 20 minutes. After 2 months of weekly, transcranial LED treatments, increased to 3 hours on computer. Performs nightly home treatments (now, 5 years, age 72); if stops treating >2 weeks, regresses. P2 (age 52F) had history of closed-head injuries related to sports/military training and recent fall. MRI shows fronto-parietal cortical atrophy. Pre-LED, was not able to work for 6 months and scored below average on attention, memory and executive function. Performed nightly transcranial LED treatments at home (9 months) with similar LED device, on frontal and parietal areas. After 4 months of LED treatments, returned to work as executive consultant, international technology consulting firm. Neuropsychological testing (post- 9 months of transcranial LED) showed significant improvement in memory and executive functioning (range, +1 to +2 SD improvement). Case 2 reported reduction in PTSD symptoms.

  16. Measurement of Transcranial Distance During Head-Down Tilt Using Ultrasound

    NASA Technical Reports Server (NTRS)

    Torikoshi, Shigeyo; Ballard, R. E.; Watenpaugh, D. E.; Murthy, G.; Bowley, S.; Yost, W. T.; Hargens, Alan R.

    1995-01-01

    Exposure to microgravity probably elevates blood pressure and flow in the head which may increase intracranial volume (ICV) and pressure (ICP). Due to the slightly compliant nature of the cranium, any increase of ICP will increase ICV and transcranial distance. We used a noninvasive ultrasound technique to measure transcranial distance (frontal to occipital) during head-down tilt. Seven subjects (ages 26-53) underwent the following tilt angles: 90 deg. upright, 30 deg., 0 deg., -6 deg., -10 deg., -6 deg., 0 deg., 30 deg., and 90 deg. Each angle was maintained for 1 min. Ultrasound wave frequency was collected continuously and transcranial distance was calculated (Delta(x) = x(Delta)f/f, where x is path length and f is frequency of the wave) for each tilt angle. Frequency decreased from 503.687 kHz (90 deg. upright) to 502.619 kHz (-10 deg.). These frequencies translated to an increased transcranial distance of 0.403 mm. Although our data suggest a significant increase in transcranial distance during head-down tilt, this apparent increase may result, in part, from head-down tilt-induced subcutaneous edema or cutaneous blood volume elevation. In three subjects, when the above protocol was repeated with an ace bandage wrapped around the head to minimize such edema, the increased transcranial distance from 90 deg. to -10 deg. was reduced by 0.174 mm. Further development of the technique to quantify bone-to-bone expansion unconfounded by cutaneous fluid is necessary. Therefore, this ultrasound technique may provide measurements of changes in cranial dimensions during microgravity.

  17. Acceleration of image analyst training with transcranial direct current stimulation.

    PubMed

    McKinley, R Andy; McIntire, Lindsey; Bridges, Nathaniel; Goodyear, Charles; Bangera, Nitin B; Weisend, Michael P

    2013-12-01

    Humans today are routinely and increasingly presented with vast quantities of data that challenge their capacity for efficient processing. To restore the balance between man and machine, it is worthwhile to explore new methods for enhancing or accelerating this capacity. This study was designed to investigate the efficacy of transcranial DC stimulation (tDCS) to reduce training time and increase proficiency in spatial recognition using a simulated synthetic aperture radar (SAR) task. Twenty-seven Air Force active duty members volunteered to participate in the study. Each participant was assigned to 1 of 3 stimulation groups and received two, 90-min training sessions on a target search and identification task using SAR imagery followed by a test. The tDCS anode was applied to site F10 according to the 10-20 electroencephalographic electrode convention while the cathode was placed on the contralateral bicep. Group 1 received anodal tDCS at 2 mA for 30 min in the first training session and sham tDCS in the second session. Group 2 received the stimulation conditions in the opposite order. Group 3 did not receive stimulation at all. Results showed that participants receiving training plus tDCS attained visual search accuracies ~25% higher than those provided with sham stimulation or no stimulation. However, a corresponding performance improvement was not found in the first training session for the change detection portion of the task. This indicates that experience with the imagery is important in the tDCS-elicited performance improvements in change detection. PMID:24341718

  18. Determinants of the electric field during transcranial direct current stimulation.

    PubMed

    Opitz, Alexander; Paulus, Walter; Will, Susanne; Antunes, Andre; Thielscher, Axel

    2015-04-01

    Transcranial direct current stimulation (tDCS) causes a complex spatial distribution of the electric current flow in the head which hampers the accurate localization of the stimulated brain areas. In this study we show how various anatomical features systematically shape the electric field distribution in the brain during tDCS. We constructed anatomically realistic finite element (FEM) models of two individual heads including conductivity anisotropy and different skull layers. We simulated a widely employed electrode montage to induce motor cortex plasticity and moved the stimulating electrode over the motor cortex in small steps to examine the resulting changes of the electric field distribution in the underlying cortex. We examined the effect of skull thickness and composition on the passing currents showing that thinner skull regions lead to higher electric field strengths. This effect is counteracted by a larger proportion of higher conducting spongy bone in thicker regions leading to a more homogenous current over the skull. Using a multiple regression model we could identify key factors that determine the field distribution to a significant extent, namely the thicknesses of the cerebrospinal fluid and the skull, the gyral depth and the distance to the anode and cathode. These factors account for up to 50% of the spatial variation of the electric field strength. Further, we demonstrate that individual anatomical factors can lead to stimulation "hotspots" which are partly resistant to electrode positioning. Our results give valuable novel insights in the biophysical foundation of tDCS and highlight the importance to account for individual anatomical factors when choosing an electrode montage. PMID:25613437

  19. ELECTRICAL CONDUCTIVITY OF THE DEEP MANTLE

    E-print Network

    Cerveny, Vlastislav

    -3 ­105 s, based on observation of horizontal electric and magnetic fields, scales up to hundreds's magnetic field observed at permanent geomagnetic observatories, at temporary locations, measured from ships) Electrical conductivity of the deep mantle C2C Mari´ansk´e l´azne 2010 4 / 39 #12;Earth's magnetic field main

  20. Subsolidus evolution and alteration of titanomagnetite in ocean ridge basalts from Deep Sea Drilling Project/Ocean Drilling Program Hole 504B9 Leg 83: Implications for the timing of magnetization

    NASA Astrophysics Data System (ADS)

    Shau, Y.-H.; Torii, M.; Horng, C.-S.; Peacor, D. R.

    2000-10-01

    Magnetic minerals in six samples of oceanic basalts of the transition zone and upper sheeted dikes from Deep Sea Drilling Project/Ocean Drilling Program (DSDP/ODP) Hole 504B, Leg 83, were studied by methods of rock magnetism and transmission electron microscopy (TEM). TEM observations showed that the magnetic mineral in these basalts is end-member magnetite (TMO) of extremely fine-grain size (30-100 nm) primarily in the range of pseudosingle-domain magnetite, consistent with the rock magnetic properties including hysteresis parameters, Curie temperature, and low-temperature measurements (Verwey transition). Magnetite formed by two different processes: (1) oxidation-"exsolution," true exsolution, and hydrothermal alteration, and (2) oxidation-exsolution, a second stage of oxidation-exsolution, and hydrothermal alteration. The primary titanomagnetite (TM60-70) that crystallized from the melt thus evolved to end-member magnetite coexisting with titanite (sphene), kassite, ulvöspinel (TM ˜ 87), and ilmenite on a submicroscopic scale. On the basis of the formation mechanisms of the magnetic carrier, the primary titanomagnetite (TM ˜ 60) with Curie temperature of ˜180°C did not acquire thermoremanent magnetization (TRM) in these basalts. Instead, the Ti-bearing magnetite (TM ˜ 10-20) that formed as oxidized or exsolved lamellae acquired its first thermal chemical remanent magnetization (CRM) at ˜ 500-400°C during subsolidus cooling. Upon the onset of hydrothermal alteration the recrystallized end-member magnetite acquired a second CRM. The natural remanent magnetization of the basalts from the transition zone and upper sheeted dikes is therefore characteristic of CRMs that were acquired when titanomagnetite altered, in part, to magnetite during subsolidus cooling and hydrothermal alteration close to the ridge axis.

  1. Magnetism

    NSDL National Science Digital Library

    David Stern

    This overview of magnetism provides a brief history prior to 1600 and continues with the work of William Gilbert, Hans Christian Oersted, and Andre-Marie Ampere in describing and exploring the magnetosphere and learning the role that electric current plays in producing magnetism. Magnetic field lines are then discussed, citing the work of Michael Faraday. The work of James Clerk Maxwell and Heinrich Hertz is mentioned in a discussion of the relationship of light waves and radio waves as part of the electromagnetic spectrum.

  2. Validation of finite element model of transcranial electrical stimulation using scalp potentials: implications for clinical dose

    NASA Astrophysics Data System (ADS)

    Datta, Abhishek; Zhou, Xiang; Su, Yuzhou; Parra, Lucas C.; Bikson, Marom

    2013-06-01

    Objective. During transcranial electrical stimulation, current passage across the scalp generates voltage across the scalp surface. The goal was to characterize these scalp voltages for the purpose of validating subject-specific finite element method (FEM) models of current flow. Approach. Using a recording electrode array, we mapped skin voltages resulting from low-intensity transcranial electrical stimulation. These voltage recordings were used to compare the predictions obtained from the high-resolution model based on the subject undergoing transcranial stimulation. Main results. Each of the four stimulation electrode configurations tested resulted in a distinct distribution of scalp voltages; these spatial maps were linear with applied current amplitude (0.1 to 1 mA) over low frequencies (1 to 10 Hz). The FEM model accurately predicted the distinct voltage distributions and correlated the induced scalp voltages with current flow through cortex. Significance. Our results provide the first direct model validation for these subject-specific modeling approaches. In addition, the monitoring of scalp voltages may be used to verify electrode placement to increase transcranial electrical stimulation safety and reproducibility.

  3. The Effect of Sleep on Intracranial Hemodynamics: A Transcranial Doppler Study

    Microsoft Academic Search

    Asma Q. Fischer; Michael A. Taormina; Bushra Akhtar; Bashir A. Chaudhary

    1991-01-01

    The effect of sleep on intracranial blood flow velocities has not been reported in children or adults, even though blood flow velocities are evaluated for clinical purposes during both sleep and wakefulness. We report the effect of sleep on intracranial blood flow velocities of 11 healthy individuals (five children and six adults) who were monitored by polysomnography and transcranial Doppler

  4. Effects of acoustic heterogeneities on transcranial brain imaging with microwave-induced thermoacoustic tomography

    E-print Network

    Wang, Lihong

    -induced thermoacoustic tomography Xing Jin Department of Biomedical Engineering, Texas A&M University, 3120 TAMU, College: thermoacoustic tomography, transcranial brain imaging, acoustic heterogeneities I. INTRODUCTION Microwave-induced thermoacoustic tomography TAT is a noninvasive and nonionizing imaging modality that can dif- ferentiate

  5. Vision Sciences Society Effects of transcranial electrical stimulation on human motion detection

    E-print Network

    Krekelberg, Bart

    Vision Sciences Society Effects of transcranial electrical stimulation on human motion detection understanding of the neural mechanisms that produce these effects in the intact human brain is very limited. We processing by stimulating over the relatively well explored human visual motion processing area, hMT+. We

  6. Predicting the behavioral impact of transcranial direct current stimulation: issues and limitations.

    PubMed

    de Berker, Archy O; Bikson, Marom; Bestmann, Sven

    2013-01-01

    The transcranial application of weak currents to the human brain has enjoyed a decade of widespread use, providing a simple and powerful tool for non-invasively altering human brain function. However, our understanding of current delivery and its impact upon neural circuitry leaves much to be desired. We argue that the credibility of conclusions drawn with transcranial direct current stimulation (tDCS) is contingent upon realistic explanations of how tDCS works, and that our present understanding of tDCS limits the technique's use to localize function in the human brain. We outline two central issues where progress is required: the localization of currents, and predicting their functional consequence. We encourage experimenters to eschew simplistic explanations of mechanisms of transcranial current stimulation. We suggest the use of individualized current modeling, together with computational neurostimulation to inform mechanistic frameworks in which to interpret the physiological impact of tDCS. We hope that through mechanistically richer descriptions of current flow and action, insight into the biological processes by which transcranial currents influence behavior can be gained, leading to more effective stimulation protocols and empowering conclusions drawn with tDCS. PMID:24109445

  7. Predicting the behavioral impact of transcranial direct current stimulation: issues and limitations

    PubMed Central

    de Berker, Archy O.; Bikson, Marom; Bestmann, Sven

    2013-01-01

    The transcranial application of weak currents to the human brain has enjoyed a decade of widespread use, providing a simple and powerful tool for non-invasively altering human brain function. However, our understanding of current delivery and its impact upon neural circuitry leaves much to be desired. We argue that the credibility of conclusions drawn with transcranial direct current stimulation (tDCS) is contingent upon realistic explanations of how tDCS works, and that our present understanding of tDCS limits the technique’s use to localize function in the human brain. We outline two central issues where progress is required: the localization of currents, and predicting their functional consequence. We encourage experimenters to eschew simplistic explanations of mechanisms of transcranial current stimulation. We suggest the use of individualized current modeling, together with computational neurostimulation to inform mechanistic frameworks in which to interpret the physiological impact of tDCS. We hope that through mechanistically richer descriptions of current flow and action, insight into the biological processes by which transcranial currents influence behavior can be gained, leading to more effective stimulation protocols and empowering conclusions drawn with tDCS. PMID:24109445

  8. Transcranial Sonography Reveals Cerebellar, Nigral, and Forebrain Abnormalities in Friedreich’s Ataxia

    Microsoft Academic Search

    Matthis Synofzik; Jana Godau; Tobias Lindig; Ludger Schöls; Daniela Berg

    2011-01-01

    Background: Friedreich’s ataxia (FA) is essentially characterized by degeneration of the dorsal root ganglia, the dorsal nuclei of Clarke, and the long spinal fiber tracts, yet there is accumulating evidence that neurodegeneration extends beyond these predilection sites. Transcranial sonography (TCS) has evolved as a valuable complementary neuroimaging tool in the assessment of neurodegenerative diseases due to its capacity to well

  9. Detection of Right-to-Left Shunt with Ultrasound Contrast Agent and Transcranial Doppler Sonography

    Microsoft Academic Search

    M. Jauss; E. Zanette

    2000-01-01

    An international Consensus Meeting to determine a standard in the examination technique for the detection of right-to-left shunt (RLS) using contrast transcranial Doppler sonography (TCD) led to the following recommendations to standardize the examination procedure: The patient should be prepared with an 18-gauge needle inserted into the cubital vein and should be in the supine position. Insonation of at least

  10. Validation of Transcranial Doppler Sonography in the Assessment of Patent Foramen Ovale

    Microsoft Academic Search

    G. Paolo Anzola; E. Renaldini; M. Magoni; A. Costa; M. Cobelli; M. Guindani

    1995-01-01

    Transcranial Doppler sonography (TCD) can detect the passage through the middle cerebral artery of microbubbles present in intravenous injected saline when an intracardiac right-to-left shunt occurs. Given the increasingly recognized importance of patent foramen ovale (PFO) as a possible anatomical factor predisposing to stroke, we tried to assess the efficiency of TCD in the evaluation of PFO in comparison to

  11. Determination of optimal electrode positions for transcranial direct current stimulation (tDCS)

    Microsoft Academic Search

    Chang-Hwan Im; Hui-Hun Jung; Jung-Do Choi; Soo Yeol Lee; Ki-Young Jung

    2008-01-01

    The present study introduces a new approach to determining optimal electrode positions in transcranial direct current stimulation (tDCS). Electric field and 3D conduction current density were analyzed using 3D finite element method (FEM) formulated for a dc conduction problem. The electrode positions for minimal current injection were optimized by changing the Cartesian coordinate system into the spherical coordinate system and

  12. An Automated Method for High-Definition Transcranial Direct Current Stimulation Modeling*

    E-print Network

    Parra, Lucas C.

    stimulation (tDCS) therapy. I. INTRODUCTION Transcranial direct current stimulation (tDCS) applies weak for a number of neurological disorders such as depression, fibromyalgia and stroke [4]-[7]. In conventional tDCS and result in non-focal current distributions on the brain. In contrast, high-definition tDCS (HD-tDCS) uses

  13. Empirical research Enhancing vigilance in operators with prefrontal cortex transcranial direct current

    E-print Network

    Parasuraman, Raja

    current stimulation (tDCS) Jeremy T. Nelson a,b , R. Andy McKinley c, , Edward J. Golob a , Joel S. Warm c prefrontal transcranial direct current stimulation (tDCS) at one of two different time points during a vigilance task (early or late). The impact of tDCS was ex- amined using measures of behavior, hemispheric

  14. Effects of Transcranial Direct Current Stimulation (tDCS) on Behaviour and Electrophysiology of Language Production

    ERIC Educational Resources Information Center

    Wirth, Miranka; Rahman, Rasha Abdel; Kuenecke, Janina; Koenig, Thomas; Horn, Helge; Sommer, Werner; Dierks, Thomas

    2011-01-01

    Excitatory anodal transcranial direct current stimulation (A-tDCS) over the left dorsal prefrontal cortex (DPFC) has been shown to improve language production. The present study examined neurophysiological underpinnings of this effect. In a single-blinded within-subject design, we traced effects of A-tDCS compared to sham stimulation over the left…

  15. Original Research Task-specific facilitation of cognition by cathodal transcranial direct current

    E-print Network

    Miall, Chris

    Keywords: Cerebellum tDCS Cognition a b s t r a c t A role for the cerebellum in cognition is controversial using transcranial Direct Current Stimulation (tDCS) during two cognitive tasks that require comparable or cathodal tDCS over the cerebellum. Participants' performance in the difficult PASST task significantly

  16. Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex Modulates Repetition

    E-print Network

    Gosselin, Frédéric

    and learning of unfamiliar faces remains unclear. Transcranial direct current stimulation (tDCS) transiently excitability modulation by tDCS would cause polarity-dependent modulations of N170 RS during encoding underwent three tDCS conditions in random order at ,72 hour intervals: right anodal/left cathodal, right

  17. Transcranial Direct Current Stimulation Augments Perceptual Sensitivity and 24-Hour Retention in a

    E-print Network

    Parasuraman, Raja

    Abstract We have previously shown that transcranial direct current stimulation (tDCS) improved performance of a complex visual perceptual learning task (Clark et al. 2012). However, it is not known whether tDCS can of the right inferior frontal cortex using tDCS on perceptual learning and retention in 37 healthy participants

  18. Comparing the Efficacy of Excitatory Transcranial Stimulation Methods Measuring Motor Evoked Potentials

    PubMed Central

    Fritzsche, Georg

    2014-01-01

    The common aim of transcranial stimulation methods is the induction or alterations of cortical excitability in a controlled way. Significant effects of each individual stimulation method have been published; however, conclusive direct comparisons of many of these methods are rare. The aim of the present study was to compare the efficacy of three widely applied stimulation methods inducing excitability enhancement in the motor cortex: 1?mA anodal transcranial direct current stimulation (atDCS), intermittent theta burst stimulation (iTBS), and 1?mA transcranial random noise stimulation (tRNS) within one subject group. The effect of each stimulation condition was quantified by evaluating motor-evoked-potential amplitudes (MEPs) in a fixed time sequence after stimulation. The analyses confirmed a significant enhancement of the M1 excitability caused by all three types of active stimulations compared to sham stimulation. There was no significant difference between the types of active stimulations, although the time course of the excitatory effects slightly differed. Among the stimulation methods, tRNS resulted in the strongest and atDCS significantly longest MEP increase compared to sham. Different time courses of the applied stimulation methods suggest different underlying mechanisms of action. Better understanding may be useful for better targeting of different transcranial stimulation techniques. PMID:24804104

  19. Does Long-Term Continuous Transcranial Doppler Monitoring Require a Pause for Safer Use?

    Microsoft Academic Search

    Kiyotaka Nakagawa; Toshihiro Ishibashi; Masato Matsushima; Yasumasa Tanifuji; Yoshikiyo Amaki; Hiroshi Furuhata

    2007-01-01

    Background: Transcranial Doppler sonography (TCD) has been used widely for long-term monitoring of cerebral blood flow without adverse reports. However, attention has not been adequately paid to the fact that an increase in the time period of TCD insonation causes brain temperature to rise due to ultrasound absorption by tissue and the skull. We measured the actual temperature rise in

  20. Effects of Induced Hypertension on Transcranial Doppler Ultrasound Velocities in Patients After Subarachnoid Hemorrhage

    Microsoft Academic Search

    E. M. Manno; D. R. Gress; L. H. Schwamm; M. N. Diringer; C. S. Ogilvy

    Background and Purpose—Transcranial doppler ultrasound (TCD) is used after subarachnoid hemorrhage to detect cerebral vasospasm and is often treated with induced hypertension. Cerebral autoregulation, however, may be disturbed in this population, raising the possibility that TCD velocities may be elevated by induced hypertension. To study this possibility, we performed continuous TCD monitoring of the middle cerebral artery during the induction

  1. Prevention of postoperative thrombotic stroke after carotid endarterectomy: The role of transcranial Doppler ultrasound

    Microsoft Academic Search

    Nikki Lennard; Julia Smith; Joanne Dumville; Richard Abbott; David H. Evans; Nicholas J. M. London; Peter R. F. Bell; A. Ross Naylor

    1997-01-01

    Purpose: To determine the incidence of particulate embolization after carotid endarterectomy (CEA), the effect of dextran-40 infusion in patients with sustained postoperative embolization, and the impact of transcranial Doppler (TCD) monitoring plus adjuvant dextran therapy on the rate of postoperative carotid thrombosis.Methods: Prospective study in 100 patients who underwent CEA with 6-hour postoperative monitoring using a TCD that was modified

  2. Differentiation between emboli and artefacts using dual-gated transcranial Doppler ultrasound

    Microsoft Academic Search

    Julia L. Smith; David H. Evans; Lingke Fan; Peter R. F. Bell; A. Ross Naylor

    1996-01-01

    It is well documented that transcranial Doppler ultrasound has the ability to detect cerebral emboli. During intraoperative patient monitoring studies, many signals due to artefact (probe motion, patient movement or surgical manipulation) are also detected and can be difficult to distinguish from genuine embolic events. We have constructed a Doppler system that can simultaneously range-gate at two separate depths, in

  3. Transcranial electrical motor evoked potentials as a prognostic indicator for motor recovery in stroke patients

    Microsoft Academic Search

    M Dominkus; W Grisold; V Jelinek

    1990-01-01

    Transcranial electrical motor evoked potentials (MEP) were examined in 33 patients within three days after stroke. Normal values for MEP and motor central conduction time (CCT) were obtained in 46 healthy controls whose MEPs were evaluated during slight voluntary muscle contraction and at rest. Two months later 23 patients were re-examined clinically and electrophysiologically. Motor function change was correlated with

  4. Transcranial Doppler Monitoring During Carotid Endarterectomy Helps to Identify Patients at Risk of Postoperative Hyperperfusion

    Microsoft Academic Search

    JE Dalman; ICM Beenakkers; FL Moll; JA Leusink; RGA Ackerstaff

    1999-01-01

    Objectives: to investigate whether transcranial Doppler (TCD) monitoring can identify patients at risk of hyperperfusion, and whether active postoperative treatment of selected patients decreases the risk of intracerebral haemorrhage (ICH). Design: a case cohort study of 688 patients undergoing carotid endarterectomy (CEA) with intraoperative TCD monitoring. Methods: sixty-two patients (9%) fulfilled the TCD criteria for hyperperfusion, i.e. >100% increase of

  5. Combined carotid and transcranial color-coded sonography in acute ischemic stroke

    Microsoft Academic Search

    Kuniyasu Wada; Kazumi Kimura; Kazuo Minematsu; Masahiro Yasaka; Makoto Uchino; Takenori Yamaguchi

    2002-01-01

    The objective of this study is to clarify whether the combination of carotid duplex sonography (CD) and transcranial color-coded sonography (TCCS) can accurately detect occlusive lesions in extra and intracranial brain arteries in acute stroke patients, using angiography as the standard. Just before angiography, we performed CD and TCCS in 40 consecutive patients within 24 h after stroke onset. We

  6. Transcranial Doppler ultrasound analysis of resistive index in rostral and caudal cerebral arteries in dogs

    Microsoft Academic Search

    Minho Seo; Hojung Choi; Kichang Lee; Mincheol Choi; Junghee Yoon

    2005-01-01

    Transcranial Doppler (TCD) was carried out to determine the resistive index (RI) values of normal canine cerebral arteries and its reproducibility and to evaluate the change of cerebral vascular resistance following diuretics administration. RI values of rostral cerebral artery (RCA) were compared between fontanelle window and temporal window. Normal ranges and reproducibility of the RI values were examined in the

  7. Role of single photon emission computed tomography and transcranial doppler ultrasonography in clinical vasospasm

    Microsoft Academic Search

    Anthony Jabre; Viken Babikian; Rachel A. Powsner; Edward L. Spatz

    2002-01-01

    This report presents our experience with Transcranial Doppler (TCD) ultrasonography and Single Photon Emission Computed Tomography (SPECT) in the assessment of patients with aneurysmal subarachnoid haemorrhage (SAH). It was designed to evaluate clinical vasospasm with both TCD and SPECT and determine their diagnostic value.Twenty-eight consecutive patients were examined with both TCD and SPECT, performed within 24 hours of each other.

  8. Functional Transcranial Doppler Sonography and a Spatial Orientation Paradigm Identify the Non-Dominant Hemisphere

    ERIC Educational Resources Information Center

    Dorst, J.; Haag, A.; Knake, S.; Oertel, W. H.; Hamer, H. M.; Rosenow, F.

    2008-01-01

    Rationale: Functional transcranial Doppler sonography (fTCD) during word generation is well established for language lateralization. In this study, we evaluated a fTCD paradigm to reliably identify the non-dominant hemisphere. Methods: Twenty-nine right-handed healthy subjects (27.1 [plus or minus] 7.6 years) performed the "cube perspective test"…

  9. Cerebral Lateralization and General Intelligence: Gender Differences in a Transcranial Doppler Study

    ERIC Educational Resources Information Center

    Njemanze, P.C.

    2005-01-01

    The present study evaluated cerebral lateralization during Raven's progressive matrices (RPM) paradigm in female and male subjects. Bilateral simultaneous transcranial Doppler (TCD) ultrasound was used to measure mean blood flow velocities (MBFV) in the right and left middle cerebral arteries (MCAs) in 24 (15 females and 9 males) right-handed…

  10. Atypical Cerebral Lateralisation in Adults with Compensated Developmental Dyslexia Demonstrated Using Functional Transcranial Doppler Ultrasound

    ERIC Educational Resources Information Center

    Illingworth, Sarah; Bishop, Dorothy V. M.

    2009-01-01

    Functional transcranial Doppler ultrasound (fTCD) is a relatively new and non-invasive technique that assesses cerebral lateralisation through measurements of blood flow velocity in the middle cerebral arteries. In this study fTCD was used to compare functional asymmetry during a word generation task between a group of 30 dyslexic adults and a…

  11. d Original Contribution SIMULTANEOUS BILATERAL REAL-TIME 3-D TRANSCRANIAL ULTRASOUND

    E-print Network

    Smith, Stephen

    been proposed as a rapid, portable alternative imaging modality to examine stroke patients in pre-hospital or emergency room settings. However, in performing transcranial ultrasound exam- inations, 8%­29% of patients has been demonstrated in various pre- hospital settings including ambulances, emergency heli- copters

  12. Transcranial direct current stimulation for the outpatient treatment of poor-responder depressed patients

    Microsoft Academic Search

    B. Dell’Osso; S. Zanoni; R. Ferrucci; M. Vergari; F. Castellano; N. D’Urso; C. Dobrea; B. Benatti; C. Arici; A. Priori; A. C. Altamura

    Transcranial direct current stimulation (tDCS) is a selective, painless, brain stimulation technique that allows the electric stimulation of specific cortical regions. TDCS has been recently used as investigational intervention for major depression and treatment resistant depression (TRD) with encouraging results. The present study was aimed to investigate the efficacy and tolerability of tDCS in major depressives with poor response to

  13. Transcranial direct current stimulation in severe, drug-resistant major depression

    Microsoft Academic Search

    R. Ferrucci; M. Bortolomasi; M. Vergari; L. Tadini; B. Salvoro; M. Giacopuzzi; S. Barbieri; A. Priori

    2009-01-01

    BackgroundThough antidepressant drugs are the treatment of choice for severe major depression, a number of patients do not improve with pharmacologic treatment. This study aimed to assess the effects of transcranial direct current stimulation (tDCS) in patients with severe, drug-resistant depression.

  14. Transcranial Direct Current Stimulation Over Somatosensory Cortex Decreases ExperimentallyInduced Acute Pain Perception

    Microsoft Academic Search

    Andrea Antal; Nadine Brepohl; Csaba Poreisz; Klara Boros; Gabor Csifcsak; Walter Paulus

    2008-01-01

    Objective: Multiple cortical areas including the primary soma- tosensory cortex are known to be involved in nociception. The aim of this study was to investigate the effect of transcranial direct current stimulation (tDCS) that modulates the cortical excitability painlessly and noninvasively, over somatosensory cortex on acute pain perception induced with a Tm:YAG laser. Methods: Subjective pain rating scores and amplitude

  15. Deep learning.

    PubMed

    LeCun, Yann; Bengio, Yoshua; Hinton, Geoffrey

    2015-05-28

    Deep learning allows computational models that are composed of multiple processing layers to learn representations of data with multiple levels of abstraction. These methods have dramatically improved the state-of-the-art in speech recognition, visual object recognition, object detection and many other domains such as drug discovery and genomics. Deep learning discovers intricate structure in large data sets by using the backpropagation algorithm to indicate how a machine should change its internal parameters that are used to compute the representation in each layer from the representation in the previous layer. Deep convolutional nets have brought about breakthroughs in processing images, video, speech and audio, whereas recurrent nets have shone light on sequential data such as text and speech. PMID:26017442

  16. Latin American Consensus on the use of transcranial Doppler in the diagnosis of brain death

    PubMed Central

    2014-01-01

    Transcranial Doppler evaluates cerebral hemodynamics in patients with brain injury and is a useful technical tool in diagnosing cerebral circulatory arrest, usually present in the brain-dead patient. This Latin American Consensus was formed by a group of 26 physicians experienced in the use of transcranial Doppler in the context of brain death. The purpose of this agreement was to make recommendations regarding the indications, technique, and interpretation of the study of transcranial ultrasonography in patients with a clinical diagnosis of brain death or in the patient whose clinical diagnosis presents difficulties; a working group was formed to enable further knowledge and to strengthen ties between Latin American physicians working on the same topic. A review of the literature, concepts, and experiences were exchanged in two meetings and via the Internet. Questions about pathophysiology, equipment, techniques, findings, common problems, and the interpretation of transcranial Doppler in the context of brain death were answered. The basic consensus statements are the following: cerebral circulatory arrest is the final stage in the evolution of progressive intracranial hypertension, which is visualized with transcranial Doppler as a "pattern of cerebral circulatory arrest". The following are accepted as the standard of cerebral circulatory arrest: reverberant pattern, systolic spikes, and absence of previously demonstrated flow. Ultrasonography should be used - in acceptable hemodynamic conditions - in the anterior circulation bilaterally (middle cerebral artery) and in the posterior (basilar artery) territory. If no ultrasonographic images are found in any or all of these vessels, their proximal arteries are acceptable to be studied to look for a a pattern of cerebral circulatory arrest. PMID:25295818

  17. The application of sparse arrays in high frequency transcranial focused ultrasound therapy: A simulation study

    SciTech Connect

    Pajek, Daniel, E-mail: dpajek@sri.utoronto.ca; Hynynen, Kullervo [Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N3M5 (Canada)] [Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N3M5 (Canada)

    2013-12-15

    Purpose: Transcranial focused ultrasound is an emerging therapeutic modality that can be used to perform noninvasive neurosurgical procedures. The current clinical transcranial phased array operates at 650 kHz, however the development of a higher frequency array would enable more precision, while reducing the risk of standing waves. However, the smaller wavelength and the skull's increased distortion at this frequency are problematic. It would require an order of magnitude more elements to create such an array. Random sparse arrays enable steering of a therapeutic array with fewer elements. However, the tradeoffs inherent in the use of sparsity in a transcranial phased array have not been systematically investigated and so the objective of this simulation study is to investigate the effect of sparsity on transcranial arrays at a frequency of 1.5 MHz that provides small focal spots for precise exposure control. Methods: Transcranial sonication simulations were conducted using a multilayer Rayleigh-Sommerfeld propagation model. Element size and element population were varied and the phased array's ability to steer was assessed. Results: The focal pressures decreased proportionally as elements were removed. However, off-focus hotspots were generated if a high degree of steering was attempted with very sparse arrays. A phased array consisting of 1588 elements 3 mm in size, a 10% population, was appropriate for steering up to 4 cm in all directions. However, a higher element population would be required if near-skull sonication is desired. Conclusions: This study demonstrated that the development of a sparse, hemispherical array at 1.5 MHz could enable more precision in therapies that utilize lower intensity sonications.

  18. Deep Lysimeter

    DOEpatents

    Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)

    2004-06-01

    A deep lysimeter including a hollow vessel having a chamber, a fill conduit extending into the chamber through apertures, a semi-permeable member mounted on the vessel and in fluid communication with the fill conduit, and a line connection for retrieving the lysimeter.

  19. Deep Time

    NSDL National Science Digital Library

    WPSU

    2010-05-04

    In this video a Penn State professor refers to National Park canyons carved out by water and wind as he explains “deep time” - the notion that the earth is billions of years old; another professor states how the theory of evolution is supported by evidence of an ancient Earth recorded in rocks.

  20. Preliminary Evidence That Anodal Transcranial Direct Current Stimulation Enhances Time to Task Failure of a Sustained Submaximal Contraction

    PubMed Central

    Williams, Petra S.; Hoffman, Richard L.; Clark, Brian C.

    2013-01-01

    The purpose of this study was to determine whether anodal transcranial direct current stimulation (tDCS) delivered while performing a sustained submaximal contraction would increase time to task failure (TTF) compared to sham stimulation. Healthy volunteers (n?=?18) performed two fatiguing contractions at 20% of maximum strength with the elbow flexors on separate occasions. During fatigue task performance, either anodal or sham stimulation was delivered to the motor cortex for up to 20 minutes. Transcranial magnetic stimulation (TMS) was used to assess changes in cortical excitability during stimulation. There was no systematic effect of the anodal tDCS stimulation on TTF for the entire subject set (n?=?18; p?=?0.64). Accordingly, a posteriori subjects were divided into two tDCS-time groups: Full-Time (n?=?8), where TTF occurred prior to the termination of tDCS, and Part-Time (n?=?10), where TTF extended after tDCS terminated. The TTF for the Full-Time group was 31% longer with anodal tDCS compared to sham (p?=?0.04), whereas TTF for the Part-Time group did not differ (p?=?0.81). Therefore, the remainder of our analysis addressed the Full-Time group. With anodal tDCS, the amount of muscle fatigue was 6% greater at task failure (p?=?0.05) and the amount of time the Full-Time group performed the task at an RPE between 8–10 (“very hard”) increased by 38% (p?=?0.04) compared to sham. There was no difference in measures of cortical excitability between stimulation conditions (p?=?0.90). That the targeted delivery of anodal tDCS during task performance both increased TTF and the amount of muscle fatigue in a subset of subjects suggests that augmenting cortical excitability with tDCS enhanced descending drive to the spinal motorpool to recruit more motor units. The results also suggest that the application of tDCS during performance of fatiguing activity has the potential to bolster the capacity to exercise under conditions required to derive benefits due to overload. PMID:24349067

  1. Improved Cognitive Function After Transcranial, Light-Emitting Diode Treatments in Chronic, Traumatic Brain Injury: Two Case Reports

    E-print Network

    Naeser, Margaret A.

    Objective: Two chronic, traumatic brain injury (TBI) cases, where cognition improved following treatment with red and near-infrared light-emitting diodes (LEDs), applied transcranially to forehead and scalp areas, are ...

  2. Anodal Transcranial Direct Current Stimulation of the Motor Cortex Ameliorates Chronic Pain and Reduces Short Intracortical Inhibition

    Microsoft Academic Search

    Andrea Antal; Daniella Terney; Stefanie Kühnl; Walter Paulus

    2010-01-01

    ContextConsecutive sessions of transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) may be a suitable therapy to treat chronic pain, as it can modulate neural activities in the stimulated and interconnected regions.

  3. Deep Brain Stimulation effects in Dystonia: Time course of electrophysiological changes in early treatment

    PubMed Central

    Ruge, Diane; Tisch, Stephen; Hariz, Marwan I.; Zrinzo, Ludvic; Bhatia, Kailash P.; Quinn, Niall P.; Jahanshahi, Marjan; Limousin, Patricia; Rothwell, John C.

    2011-01-01

    Background Deep brain stimulation (DBS) to the internal globus pallidus is an effective treatment for primary dystonia. The optimal clinical effect often occurs only weeks to months after starting stimulation. To better understand the underlying electrophysiological changes in this period we assessed longitudinally two pathophysiological markers of dystonia in patients prior to and in the early treatment period (1,3,6 months) after DBS-surgery. Methods Transcranial magnetic stimulation was used to track changes in short latency intracortical inhibition (SICI), a measure of excitability of GABAA-ergic corticocortical connections and long-term potentiation-like synaptic plasticity (as a response to paired associative stimulation, PAS). DBS remained ON for the duration of the study. Results Prior to surgery, inhibition was reduced and plasticity increased in patients compared to healthy controls. Following surgery and commencement of DBS, SICI increased towards normal levels over the following months with the same monotonic time course as the patients' clinical benefit. In contrast, synaptic plasticity changed rapidly following a non-monotonic time course: it was absent early (1 month) after surgery, and then over the following months increased towards levels observed in healthy individuals. Conclusion We postulate that before surgery pre-existing high levels of plasticity form strong memories of dystonic movement patterns. When DBS is turned ON, it disrupts abnormal basal ganglia signals resulting in the absent response to PAS at one month. Clinical benefit is delayed because engrams of abnormal movement persist and take time to normalise. Our observations suggest that plasticity may be a driver of long term therapeutic effects of DBS in dystonia. PMID:21547950

  4. Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

    PubMed Central

    Guleyupoglu, Berkan; Schestatsky, Pedro; Edwards, Dylan; Fregni, Felipe; Bikson, Marom

    2013-01-01

    Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of trans-cranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES. PMID:23954780

  5. Classification of methods in transcranial electrical stimulation (tES) and evolving strategy from historical approaches to contemporary innovations.

    PubMed

    Guleyupoglu, Berkan; Schestatsky, Pedro; Edwards, Dylan; Fregni, Felipe; Bikson, Marom

    2013-10-15

    Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES. PMID:23954780

  6. Morphogenesis of maze-like magnetic domains Cdric Bathany,1 Malane Le Romancer,1,2 Jason N. Armstrong,1 and Harsh Deep Chopra1,*

    E-print Network

    Chopra, Harsh Deep

    Morphogenesis of maze-like magnetic domains Cédric Bathany,1 Maëlane Le Romancer,1,2 Jason N explains the morphogenesis of maze-like magnetic domains in amorphous Tb-Fe films. It is shown that the observed morphological complexity of the maze-like patterns which arise due to out-of-plane anisotropy

  7. Magnetization reversal in half-metallic epitaxial CrO2 films I. L. Siu, W. F. Egelhoff, David X. Yang, and Harsh Deep Chopra

    E-print Network

    Chopra, Harsh Deep

    . Phys. 111, 07A926 (2012) Structural, magnetic, and electron transport properties of MnBi:Fe thin films J. Appl. Phys. 111, 07E326 (2012) Control of magnetic properties of MnBi and MnBiCu thin films by Kr

  8. Changes in basal ganglia processing of cortical input following magnetic stimulation in Parkinsonism

    E-print Network

    Bar-Gad, Izhar

    Available online 31 July 2012 Keywords: Transcranial magnetic stimulation (TMS) Parkinson's disease Primate. Introduction Parkinsonism is associated with altered neurophysiological activi- ty throughout the cortico in Parkinsonism Hadass Tischler a , Anan Moran a , Katya Belelovsky a , Maya Bronfeld a , Alon Korngreen a

  9. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: AlGaN-Based Deep-Ultraviolet Light Emitting Diodes Fabricated on AlN\\/sapphire Template

    Microsoft Academic Search

    Li-Wen Sang; Zhi-Xin Qin; Hao Fang; Yan-Zhao Zhang; Tao Li; Zheng-Yu Xu; Zhi-Jian Yang; Bo Shen; Guo-Yi Zhang; Shu-Ping Li; Wei-Huang Yang; Hang-Yang Chen; Da-Yi Liu; Jun-Yong Kang

    2009-01-01

    We report on the growth and fabrication of deep ultraviolet (DUV) light emitting diodes (LEDs) on an AlN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities in the AlN layer are greatly decreased with the introduction of this buffer layer. The crystalline quality of the AlGaN epilayer is further improved by using a low-temperature

  10. Right-to-Left-Shunts Detected by Transesophageal Echocardiography and Transcranial Doppler Sonography

    Microsoft Academic Search

    Dirk W. Droste; Carsten Schmidt-Rimpler; Thomas Wichter; Ralf Dittrich; Martin Ritter; Jörg Stypmann; E. Bernd Ringelstein

    2004-01-01

    Background: Transesophageal echocardiography (TEE) and transcranial Doppler sonography (TCD) can identify right-to-left-shunts that predispose to paradoxical embolism. In a large cohort we compared the results of both techniques. Methods: 222 patients were investigated by both techniques using the contrast agent Echovist®-300 and performing each test once without and once with the Valsalva maneuver (VM). Results: TEE-proven right-to-left-shunts were detected by

  11. Is Transcranial Doppler for the Detection of Venous-to-Arterial Circulation Shunts Reproducible?

    Microsoft Academic Search

    S. Sastry; K. Daly; T. Chengodu; C. McCollum

    2007-01-01

    Background: We investigated the reproducibility of contrast transcranial Doppler (TCD), a safe non-invasive test for investigation of venous-to-arterial circulation shunts (v-aCS), usually patent foramen ovale, in young stroke patients. We also investigated whether microbubble contrast was reproducible and whether the addition of blood to agitated saline contrast affected the number of microbubbles produced. Methods: TCD investigation for v-aCS was repeated

  12. Cerebellar Transcranial Direct Current Stimulation Impairs the Practice-dependent Proficiency Increase in Working Memory

    Microsoft Academic Search

    R. Ferrucci; S. Marceglia; M. Vergari; F. Cogiamanian; S. Mrakic-sposta; F. Mameli; S. Zago; S. Barbieri; A. Priori

    2008-01-01

    How the cerebellum is involved in the practice and proficiency of non-motor functions is still unclear. We tested whether transcranial direct current stimulation (tDCS) over the cerebellum (cerebellar tDCS) induces after-effects on the practice-dependent increase in the proficiency of a working memory (WM) task (Sternberg test) in 13 healthy subjects. We also assessed the effects of cerebellar tDCS on visual

  13. After-effects of transcranial direct current stimulation (tDCS) on cortical spreading depression

    Microsoft Academic Search

    David Liebetanz; Felipe Fregni; Katia K. Monte-Silva; Manuella B. Oliveira; Ângela Amâncio-dos-Santos; Michael A. Nitsche; Rubem C. A. Guedes

    2006-01-01

    Abnormal cortical excitability influences susceptibility to cortical spreading depression (CSD) in migraine. Because transcranial direct current stimulation (tDCS) is capable of inducing lasting changes of cortical excitability, we investigated the after-effects of tDCS on the propagation velocity of CSD in the rat. Twenty-five anesthetised rats received either anodal, cathodal or sham tDCS. The stimulation was applied for 20min at a

  14. Effects of transcranial direct current stimulation over the human motor cortex on corticospinal and transcallosal excitability

    Microsoft Academic Search

    N. Lang; M. A. Nitsche; W. Paulus; J. C. Rothwell; R. N. Lemon

    2004-01-01

    Weak transcranial direct current stimulation (tDCS) can induce long lasting changes in cortical excitability. In the present study we asked whether tDCS applied to the left primary motor cortex (M1) also produces aftereffects distant from the site of the stimulating electrodes. We therefore tested corticospinal excitability in the left and the right M1 and transcallosal excitability between the two cortices

  15. Primary motor cortex activation by transcranial direct current stimulation in the human brain

    Microsoft Academic Search

    Yong Hyun Kwon; Myoung-Hwan Ko; Sang Ho Ahn; Yun-Hee Kim; Jun Chan Song; Chu-Hee Lee; Min Cheol Chang; Sung Ho Jang

    2008-01-01

    Transcranial direct current stimulation (tDCS) can modulate motor cortex excitability in the human brain. We attempted to demonstrate the cortical stimulation effect of tDCS on the primary motor cortex (M1) using functional MRI (fMRI). An fMRI study was performed for 11 right-handed healthy subjects at 1.5T. Anodal tDCS was applied to the scalp over the central knob of the M1

  16. Transcranial direct current stimulation (tDCS) in a realistic head model

    Microsoft Academic Search

    Rosalind J. Sadleir; Tracy D. Vannorsdall; David J. Schretlen; Barry Gordon

    2010-01-01

    Distributions of current produced by transcranial direct current stimulation (tDCS) in humans were predicted by a finite-element model representing several individual and collective refinements over prior efforts. A model of the entire human head and brain was made using a finely meshed (1.1×1.1×1.4mm3 voxel) tissue dataset derived from the MRI data set of a normal human brain. The conductivities of

  17. Validation of Transcranial Doppler With Computed Tomography Angiography in Acute Cerebral Ischemia

    Microsoft Academic Search

    Georgios Tsivgoulis; Vijay K. Sharma; Annabelle Y. Lao; Marc D. Malkoff; Andrei V. Alexandrov

    2010-01-01

    Background and Purpose—Both transcranial Doppler (TCD) and spiral computed tomography angiography (CTA) are used for noninvasive vascular assessment tools in acute stroke. We aimed to evaluate the diagnostic accuracy of TCD against CTA in patients with acute cerebral ischemia. Methods—Consecutive patients presenting to the Emergency Department with symptoms of acute (24 hours) cerebral ischemia underwent emergent high-resolution brain CTA with

  18. Utility of transcranial Doppler ultrasound for the integrative assessment of cerebrovascular function

    Microsoft Academic Search

    C. K. Willie; F. L. Colino; D. M. Bailey; Y. C. Tzeng; G. Binsted; L. W. Jones; M. J. Haykowsky; J. Bellapart; S. Ogoh; K. J. Smith; J. D. Smirl; T. A. Day; S. J. Lucas; L. K. Eller; P. N. Ainslie

    2011-01-01

    There is considerable utility in the use of transcranial Doppler ultrasound (TCD) to assess cerebrovascular function. The brain is unique in its high energy and oxygen demand but limited capacity for energy storage that necessitates an effective means of regional blood delivery. The relative low cost, ease-of-use, non-invasiveness, and excellent temporal resolution of TCD make it an ideal tool for

  19. Transcranial power M-mode Doppler ultrasound for diagnosis of patent foramen ovale

    Microsoft Academic Search

    Mark Moehring; Merrill Spencer

    2005-01-01

    Patent foramen ovale (PFO) is a right-to-left shunt (RLS) which communicates blood from the right to left atrium of the heart. PFO has been associated with stroke and, more recently, with migraine headache. Diagnosis of RLS can be accomplished effectively with transcranial power M-mode Doppler ultrasound (PMD). PMD is a modality which can be performed without the sedation required by

  20. Transcranial direct current stimulation of the prefrontal cortex modulates the desire for specific foods

    Microsoft Academic Search

    Felipe Fregni; Fernanda Orsati; Waldelle Pedrosa; Shirley Fecteau; Fatima A. M. Tome; Michael A. Nitsche; Tatiana Mecca; Elizeu C. Macedo; Alvaro Pascual-Leone; Paulo S. Boggio

    2008-01-01

    We aimed to assess whether modulation of the dorsolateral prefrontal cortex (DLFPC) with noninvasive brain stimulation, namely transcranial direct current stimulation (tDCS), modifies food craving in healthy subjects. We performed a randomized sham-controlled cross-over study in which 23 subjects received sham and active tDCS (anode left\\/cathode right and anode right\\/cathode left) of the DLPFC. Subjects were exposed to food and