Transcranial magnetic stimulation

Are We Right about the Right TPJ? A Review of Brain Stimulation and Social Cognition in the Right Temporal Parietal Junction

In the past decade, the functional role of the TPJ (Temporal Parietal Junction) has become more evident in terms of its contribution to social cognition. Studies have revealed the TPJ as a ‘distinguisher’ of self and other with research focused on non-clinical populations as well as in individuals with Autism and Type I Schizophrenia. Further research has focused on the integration of self-other distinctions with proprioception. Much of what we now know about the causal role of the right TPJ derives from TMS (Transcranial Magnetic Stimulation), rTMS repetitive Transcranial Magnetic Stimulation), and tDCS (transcranial Direct Cortical Stimulation). In this review, we focus on the role of the right TPJ as a moderator of self, which is integrated and distinct from ‘other’ and how brain stimulation has established the causal relationship between the underlying cortex and agency.

Effects of transcranial stimulation in developmental neurocognitive disorders: A critical appraisal

Non-invasive brain stimulation (NIBS) has been highlighted as a powerful tool to promote neuroplasticity, and an attractive approach to support cognitive remediation. Here we provide a systematic review of 26 papers using NIBS to ameliorate cognitive dysfunctions in three prevalent neurodevelopmental disorders: Attention-Deficit/Hyperactivity Disorder (ADHD), Developmental Dyslexia and Developmental Dyscalculia. An overview of the state of research shows a predominance of studies using repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) techniques, and an unequal distribution among clinical conditions. Regarding the utility of NIBS, the results are promising but also ambiguous. Twenty-three papers reported beneficial effects, but many of these effects were found only once or were only partially replicated and some studies even reported detrimental effects. Furthermore, most studies differed in at least one core aspect, the NIBS applied, the questionnaires and cognitive tests conducted, or the age group investigated, and sample sizes were mostly small. Hence, further studies are needed to rigorously examine the potential of NIBS in the remediation of cognitive functions. Finally, we discuss potential caveats and future directions. We reason that if adequately addressing these challenges NIBS can be feasible, with potential benefits in treating neurodevelopmental disorders.

Safe exposure distances for transcranial magnetic stimulation based on computer simulations

The results of a computer simulation examining the compliance of a given transcranial magnetic stimulation device to the 2010 International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines are presented. The objective was to update the safe distance estimates with the most current safety guidelines, as well as comparing these to values reported in previous publications. The 3D data generated was compared against results available in the literature, regarding the MCB-70 coil by Medtronic. Regarding occupational exposure, safe distances of 1.46 m and 0.96 m are derived from the simulation according to the 2003 and 2010 ICNIRP guidelines, respectively. These values are then compared to safe distances previously reported in other studies.

Semi-automatic 10/20 Identification Method for MRI-Free Probe Placement in Transcranial Brain Mapping Techniques

The International 10/20 system is an important head-surface-based positioning system for transcranial brain mapping techniques, e.g., fNIRS and TMS. As guidance for probe placement, the 10/20 system permits both proper ROI coverage and spatial consistency among multiple subjects and experiments in a MRI-free context. However, the traditional manual approach to the identification of 10/20 landmarks faces problems in reliability and time cost. In this study, we propose a semi-automatic method to address these problems. First, a novel head surface reconstruction algorithm reconstructs head geometry from a set of points uniformly and sparsely sampled on the subject's head. Second, virtual 10/20 landmarks are determined on the reconstructed head surface in computational space. Finally, a visually-guided real-time navigation system guides the experimenter to each of the identified 10/20 landmarks on the physical head of the subject. Compared with the traditional manual approach, our proposed method provides a significant improvement both in reliability and time cost and thus could contribute to improving both the effectiveness and efficiency of 10/20-guided MRI-free probe placement.

Could Hallucinogens Induce Permanent Pupillary Changes in (Ab)users? A Case Report from New Zealand

An eighteen-year-old female patient of the Caucasian ethnicity from Australasia presented with a persistently dilated pupil causing her discomfort and occasional burning sensation when she is outdoors due to oversensitivity to sunlight. However, her pupillary reaction to light (pupillary light reflex) was intact. The patient is a known user of psychedelic substances (entheogens) including LSD, NBOMe, psilocybin, and DMT. The condition affects both eyes to the same extent. Thorough medical, neurological, and radiological examinations, including an EEG and an MRI of the head and neck region, were completely normal. All these tests failed to detect any pathophysiological or anatomical abnormalities. The patient is a known case of chronic endogenous depression in association with attention deficit hyperactivity disorder, for which she is taking citalopram and Ritalin, respectively. There was neither a family history nor a similar congenital condition in her family.

Superior antidepressant effect occurring 1 month after rTMS: add-on rTMS for subjects with medication-resistant depression

Depression is a major psychiatric disorder. The standard treatment for depression is antidepressant medication, but the responses to antidepressant treatment are only partial, even poor, among 30%-45% of patients. Refractory depression is defined as depression that does not respond to antidepressant therapy after 4 weeks of use. There is evidence that repetitive transcranial magnetic stimulation (rTMS) may exert effects in treating psychiatric disorder through moderating focal neuronal functions. High-frequency rTMS on the left prefrontal area and low-frequency rTMS on the right prefrontal area were shown to be effective in alleviating depressive symptoms. Given the statistically significant antidepressant effectiveness noted, the clinical application of rTMS as a depression treatment warrants further studies. Application of rTMS as an add-on therapy would be a practical research model. High-frequency (5-20 Hz) rTMS over the left dorsolateral prefrontal cortex was found to have a significant effect on medication-resistant depression. In the present study, we not only measured the acute antidepressant effect of rTMS during treatment and immediately after its completion but also evaluated participants 1 month after completion of the treatment protocol. Study participants were divided into two groups: an active rTMS group (n = 10) and a sham group (n = 10). The active rTMS group was defined as participants who received the rTMS protocol, and the sham group was defined as participants who received a sham rTMS procedure. A significant Hamilton Depression Rating Scale score reduction was observed in both groups after the fifth and tenth treatments. However, those in the active rTMS group maintained their improvement as measured one month after completion of the rTMS protocol. Participants who received active rTMS were more likely to have persistent improvement in depression scores than participants who received sham rTMS.

Repetitive transcranial magnetic stimulation for tinnitus

BACKGROUND

Tinnitus is the perception of sound, in the ear or in the head, in the absence of any external acoustic stimulation. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive means of inducing electrical currents in the brain, and has received increasing attention in recent years for the treatment of many neuropsychiatric disorders, including tinnitus.

OBJECTIVES

To assess the effectiveness and safety of rTMS versus placebo in patients with tinnitus.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the most recent search was 24 May 2011.

SELECTION CRITERIA

Randomised controlled trials of rTMS versus sham rTMS.

DATA COLLECTION AND ANALYSIS

Two review authors reviewed the titles, abstracts and keywords of all records retrieved. Three review authors independently collected and extracted data, and assessed the risk of bias of the trials.

MAIN RESULTS

Five trials comprising of 233 participants met our inclusion criteria. Each study described the use of a different rTMS device that delivered different waveforms at different frequencies. All five trials were relatively small studies but generally they demonstrated a low risk of bias.When considering the impact of tinnitus on patients' quality of life, the results of only one study demonstrated a statistically significant improvement in Tinnitus Handicap Inventory (THI) scores at four months follow-up (defined as a 'partial improvement' by the study authors (THI reduction of 21% to 80%)) when low-frequency rTMS was compared with a sham control treatment. However, no statistically significant improvement was demonstrated by another two studies that considered rTMS at the same frequency. Furthermore, this single positive finding should be taken in the context of the many different variables which were recorded at many different points in time by the study authors.In accordance with our pre-specified subgroup analysis we extracted the data from one study to consider the differential effectiveness between 'lower' low-frequency rTMS (1 Hz) and 'higher' low-frequency rTMS (10 Hz, 25 Hz). In doing this we were able to demonstrate a statistically significant difference between rTMS employing a frequency of 1 Hz and the sham group when considering tinnitus severity and disability after four months follow-up ('partial' improvement). However, no statistically significant difference was demonstrated between 10 Hz and 25 Hz rTMS, and the sham control group, when considering the severity and disability of tinnitus at four months follow-up.When considering tinnitus loudness in patients undergoing rTMS we were able to demonstrate a statistically significant reduction in tinnitus loudness when the results of two studies were pooled (risk ratio 4.17, 95% confidence interval 1.30 to 13.40). However, this finding was based on two small trials and consequently the confidence interval was particularly wide.No serious adverse effects were reported in any of the trials.

AUTHORS' CONCLUSIONS

There is very limited support for the use of low-frequency rTMS for the treatment of patients with tinnitus. When considering the impact of tinnitus on patients' quality of life, support is from a single study with a low risk of bias based on a single outcome measure at a single point in time. When considering the impact on tinnitus loudness, this is based on the analysis of pooled data with a large confidence interval.Studies suggest that rTMS is a safe treatment for tinnitus in the short-term, however there were insufficient data to provide any support for the safety of this treatment in the long-term.More prospective, randomised, placebo-controlled, double-blind studies with large sample sizes are needed to confirm the effectiveness of rTMS for tinnitus patients. Uniform, validated, tinnitus-specific questionnaires and measurement scales should be used in future studies.

Robustness of intrinsic connectivity networks in the human brain to the presence of acoustic scanner noise

Evoked responses in functional magnetic resonance imaging (fMRI) are affected by the presence of acoustic scanner noise (ASN). Particularly, stimulus-related activation of the auditory system and deactivation of the default mode network have repeatedly been shown to diminish. In contrast, little is known about the influence of ASN on the spontaneous fluctuations in brain activity that are crucial for network-related neuroimaging methods like independent component analysis (ICA) or functional and effective connectivity analysis (ECA). The present study assessed the robustness of intrinsic connectivity networks in the human brain to the presence of ASN by comparing 'silent' (sparse) and 'noisy' (continuous) acquisition schemes, both during task performance and during rest. In agreement with existing literature, ASN strongly diminished conventional evoked response levels. In contrast, ICA and ECA robustly identified similar functional networks regardless of the scanning method. ASN affected the strength of only few independent components, and effective connectivity was hardly sensitive to ASN overall. However, unexpectedly, ICA revealed notable differences in the underlying neurodynamics. In particular, low-frequency network oscillations dominated in the commonly used continuous scanning environment, but signal spectra were significantly flatter during the less noisy sparse scanning runs. We tentatively attribute these differences to the ubiquitous influence of ASN on alertness and arousal.

Transcranial low voltage pulsed electromagnetic fields in patients with treatment-resistant depression

BACKGROUND

Approximately 30% of patients with depression are resistant to antidepressant drugs. Repetitive transcranial magnetic stimulation (rTMS) has been found effective in combination with antidepressants in this patient group. The aim of this study was to evaluate the antidepressant effect of a new principle using low-intensity transcranially applied pulsed electromagnetic fields (T-PEMF) in combination with antidepressants in patients with treatment-resistant depression.

METHODS

This was a sham-controlled double-blind study comparing 5 weeks of active or sham T-PEMF in patients with treatment-resistant major depression. The antidepressant treatment, to which patients had been resistant, was unchanged 4 weeks before and during the study period. Weekly assessments were performed using both clinician-rated and patient-rated scales. The T-PEMF equipment was designed as a helmet containing seven separate coils located over the skull that generated an electrical field in tissue with orders of magnitude weaker than those generated by rTMS equipment.

RESULTS

Patients on active T-PEMF showed a clinically and statistically significant better outcome than patients treated with sham T-PEMF, with an onset of action within the first weeks of therapy. Effect size on the Hamilton 17-item Depression Rating Scale was .62 (95% confidence interval .21-1.02). Treatment-emergent side effects were few and mild.

CONCLUSION

The T-PEMF treatment was superior to sham treatment in patients with treatment-resistant depression. Few side effects were observed. Mechanism of the antidepressant action, in light of the known effects of PEMF stimulation to the brain, is discussed.

Therapeutic efficacy assessment of weak variable magnetic fields with low value of induction in patients with drug-resistant depression

BACKGROUND

The aim of this prospective study was to verify whether magnetostimulation with weak variable magnetic fields with low value of induction could enhance the effects of pharmacological therapy in drug-resistant depression.

MATERIALS AND METHODS

Thirty patients, 26 women and 4 men, with drug-resistant depression were enrolled in the study. The subjects from Group No. I (14 patients) were given fluvoxamine and treated with weak variable magnetic field using the VIOFOR JPS device; the subjects from Group No. II (16 patients) were also given fluvoxamine but they were treated with the VIOFOR JPS device in placebo mode. Changes in depressive symptoms were estimated with the 21-point Hamilton Depression Scale (HDRS), Montgomery-Asberg Depression Scale (MADRS) and Beck Depression Inventory (BDI) questionnaire.

RESULTS

After 15 days of treatment highly significant differences were revealed between the patients treated with magnetic field and the patients treated with placebo: the final HDRS score was 53% of the initial value for the group receiving combined treatment, and 86% in the placebo group (p<0.001); for MADRS score the values were 51% and 88% (p<0.001), respectively, and for BDI 60% and 87% (p<0.001). Thus, the average effect of placebo applied with fluvoxamine was a ca. 15% reduction of symptoms, while the concurrent application of magnetic field and SSRI treatment resulted in a 40-50% improvement.

CONCLUSION

Our study indicates that adding a two-week low-induction variable magnetic field stimulation to a classical pharmacologic therapy reduces the intensity of symptoms in patients with drug-resistant depressive disorders.

Quality assessment and comparison of evidence for electroconvulsive therapy and repetitive transcranial magnetic stimulation for schizophrenia: a systematic meta-review

BACKGROUND

Randomized studies directly comparing the effects of electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation (rTMS) for depression generally favour ECT. ECT and rTMS have also been investigated for chronic symptoms of schizophrenia although there are no direct comparisons available.

AIMS

We sought to determine the relative benefits and adverse outcomes of ECT and rTMS by comparing effect sizes reported in systematic reviews and to quality assess this evidence using GRADE and QUOROM guidelines.

METHOD

Included are systematic reviews with meta-analysis published since 2000, reporting results for people with a diagnosis of schizophrenia, schizoaffective disorder, schizophreniform disorder or first episode schizophrenia. Medline, Embase, CINAHL, Current Contents, PsycINFO and the Cochrane library were searched and hand searching was conducted. Data extraction and quality assessment were completed by two independent reviewers.

RESULTS

Fifty-three of 58 reviews were excluded as they did not meet inclusion criteria. The remaining five have a low probability of reporting bias and show that high quality evidence suggests a short-term, medium to large treatment effect of rTMS for auditory hallucinations (d=0.88) but not other symptoms, for people treated with concurrent antipsychotics. For ECT, high quality evidence suggests a short-term small, significant effect for improvement in global symptoms, for people with or without concurrent antipsychotics (RR=0.76). There is no evidence for longer-term therapeutic or adverse effects of either treatment.

CONCLUSIONS

It is worthwhile considering rTMS in cases where auditory hallucinations have not responded to antipsychotic medications and ECT where overall symptoms have not responded to antipsychotic medications.

Antioxidant-like effects and protective action of transcranial magnetic stimulation in depression caused by olfactory bulbectomy

We studied the effects of transcranial magnetic stimulation (TMS, 60 Hz and 0.7 mT for 4 h/day for 14 days) on oxidative and cell damage caused by olfactory bulbectomy (OBX) in Wistar rats. The levels of lipid peroxidation products and caspase-3 were enhanced by OBX, whereas it prompted a reduction in reduced glutathione (GSH) content and antioxidative enzymes activities. The treatment with TMS reverted towards normality the biomarkers indicative of oxidative stress and apoptosis. In conclusion, our data show that TMS induced a protection against cell and oxidative damage induced by OBX, as well as they support the hypothesis that oxidative stress may play an important role in depression.

Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T

RATIONALE AND OBJECTIVES

The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7 T by means of transcranial magnetic stimulation (TMS).

MATERIALS AND METHODS

TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63 minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63 minutes without scanning and lying in a separate room for 63 minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed.

RESULTS

Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7 T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences.

CONCLUSION

MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field.