Deep transcranial magnetic stimulation for the treatment of auditory hallucinations: a preliminary open-label study

Alterations in brain connectivity patterns in schizophrenia patients with auditory verbal hallucinations during low frequency repetitive transcranial magnetic stimulation

OBJECTIVE

Auditory verbal hallucinations (AVH) are a characteristic symptom of schizophrenia. Although low-frequency repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to alleviate the severity of AVH, its exact neurophysiological mechanisms remain unclear. This study aimed to elucidate the alterations in brain connectivity patterns in schizophrenia patients with AVH after low frequency rTMS. Furthermore, the relationship between these alterations and clinical outcomes was examined, thereby identifying potential biomarkers for rTMS treatment efficacy.

METHODS

A total of 30 schizophrenia patients with AVH and 33 healthy controls were recruited. The patients received 1 Hz rTMS applied to the left temporoparietal junction region over 15 days. Resting-state functional magnetic resonance imaging scans were conducted for all participants. Subsequently, degree centrality (DC) and seed-based functional connectivity (FC) analyses were employed to identify specific alterations in brain connectivity patterns after rTMS treatment.

RESULTS

At baseline, patients exhibited divergent DC patterns in the frontal, occipital, and limbic lobes compared to healthy controls. In addition, prior to treatment, patients demonstrated altered FC from the superior frontal gyrus seeds that linked to the frontal, temporal, and somatosensory regions. Following rTMS treatment, these abnormalities were notably reversed, correlating with improved clinical outcomes.

CONCLUSIONS

These findings demonstrate that schizophrenia patients with AVH exhibited atypical interactions within the frontal and temporal lobes. These alterations might be crucial biomarkers for predicting the efficacy of low frequency rTMS.

Past, present, and future of deep transcranial magnetic stimulation: A review in psychiatric and neurological disorders

Deep transcranial magnetic stimulation (DTMS) is a new non-invasive neuromodulation technique based on repetitive transcranial magnetic stimulation tech-nology. The new H-coil has significant advantages in the treatment and mechanism research of psychiatric and neurological disorders. This is due to its deep stimulation site and wide range of action. This paper reviews the clinical progress of DTMS in psychiatric and neurological disorders such as Parkinson's disease, Alzheimer's disease, post-stroke motor dysfunction, aphasia, and other neurological disorders, as well as anxiety, depression, and schizophrenia.

Assessment of treatment resistance criteria in non-invasive brain stimulation studies of schizophrenia

Novel treatment modalities, such as non-invasive brain stimulation (NIBS), typically focus on patient groups that have failed multiple treatment interventions. Despite its promise, the clinical translation of NIBS in schizophrenia has been limited. One important obstacle to implementation is the inconsistent reporting of treatment resistance in the clinical trial literature contributing to heterogeneity in reported effects. In response, we develop a numerical approach to synthesize quality of assessment of Treatment-Resistant Schizophrenia (TRS) and apply this to studies investigating therapeutic response to NIBS in patients with schizophrenia. Literature search conducted through PubMed database identified 119 studies investigating Transcranial Magnetic Stimulation and Transcranial Electrical Stimulation in treating resistant schizophrenia symptoms. A quality score out of 11 was assigned to each study based on adherence to the international consensus guidelines for TRS developed by the Treatment Response and Resistance in Psychosis (TRRIP) group. Results revealed an overall paucity of studies with thorough assessment and/or reporting of TRS phenomenon, as evidenced by a mean quality score of 3.38/11 (SD: 1.01) for trials and 5.16/11 (SD: 1.57) for case reports, though this improved minimally since the publication of consensus criteria. Most studies considered treatment-resistance as a single dimensional construct by reporting resistance of a single symptom, and failed to establish treatment adherence, resistance time course and functional impairment. We conclude that the current NIBS literature in schizophrenia do not reflect its true effects on treatment-resistance. There is an urgent need to improve assessment and reporting standards of clinical trials that target TRS.

Assessment of Cortical Plasticity in Schizophrenia by Transcranial Magnetic Stimulation

Neural plasticity refers to the capability of the brain to modify its structure and/or function and organization in response to a changing environment. Evidence shows that disruption of neuronal plasticity and altered functional connectivity between distinct brain networks contribute significantly to the pathophysiological mechanisms of schizophrenia. Transcranial magnetic stimulation has emerged as a noninvasive brain stimulation tool that can be utilized to investigate cortical excitability with the aim of probing neural plasticity mechanisms. In particular, in pathological disorders, such as schizophrenia, cortical dysfunction, such as an aberrant excitatory-inhibitory balance in cortical networks, altered cortical connectivity, and impairment of critical period timing are very important to be studied using different TMS paradigms. Studying such neurophysiological characteristics and plastic changes would help in elucidating different aspects of the pathophysiological mechanisms underlying schizophrenia. This review attempts to summarize the findings of available TMS studies with diagnostic and characterization aims, but not with therapeutic purposes, in schizophrenia. Findings provide further evidence of aberrant excitatory-inhibitory balance in cortical networks, mediated by neurotransmitter pathways such as the glutamate and GABA systems. Future studies with combining techniques, for instance, TMS with brain imaging or molecular genetic typing, would shed light on the characteristics and predictors of schizophrenia.

Transcranial Magnetic Stimulation for Positive Symptoms in Schizophrenia: A Systematic Review

Transcranial magnetic stimulation (TMS) has been proposed as a potential treatment add-on for positive symptoms in schizophrenia. To summarize the current evidence for its efficacy, we reviewed clinical trials from the last 20 years that investigated TMS for positive symptoms. We performed a search on the PubMed database for clinical trials that used TMS for the treatment of positive symptoms published in peer-reviewed journals. We excluded reviews, case reports, and opinion papers. Of the 30 studies included, the majority (n = 25) investigated auditory verbal hallucinations. Twelve studies found evidence for a positive treatment effect of TMS on positive symptoms, while 18 did not find enough evidence to conclude that TMS is effective for positive symptoms. However, the small sample size of the majority of studies is a limiting factor for the reliability of previous findings. In conclusion, evidence for an effect of TMS on positive symptoms was mixed. Since most of the studies were performed in patients with auditory verbal hallucinations, further research of TMS for other positive symptoms including thought disorder and delusions is warranted.

Tracking positive and negative symptom improvement in first-episode schizophrenia treated with risperidone using individual-level functional connectivity

BACKGROUND

To improve the treatment outcomes of patients with schizophrenia, research efforts have focused on identifying brain-based markers of treatment response. Personal characteristics regarding disease-related behaviors likely stem from inter-individual variability in the organization of brain functional systems. This study aimed to track dimension-specific changes in psychotic symptoms following risperidone treatment using individual-level functional connectivity (FC).

METHODS

A reliable cortical parcellation approach that accounts for individual heterogeneity in cortical functional anatomy was used to localize functional regions in a longitudinal cohort, consisting of 42 drug-naive first-episodes schizophrenia (FES) patients at baseline and after 8 weeks of risperidone treatment. FC was calculated in individually specified brain regions and used to predict the baseline severity and improvement of positive and negative symptoms in FES.

RESULTS

Distinct sets of individual-specific FC were separately associated with the positive and negative symptom burden at baseline, which could be used to track the corresponding symptom resolution in FES patients following risperidone treatment. Between-network connections of the fronto-parietal network (FPN) contributed the most to predicting the positive symptom domain. A combination of between-network connections of the default mode network, FPN, and within-network connections of the FPN contributed markedly to the prediction model of negative symptom.

CONCLUSION

This novel study, which accounts for individual brain variation, take a step toward establishing individual-specific theranostic biomarkers in schizophrenia.

Engineering in vitro human neural tissue analogs by 3D bioprinting and electrostimulation

There is a fundamental need for clinically relevant, reproducible, and standardized in vitro human neural tissue models, not least of all to study heterogenic and complex human-specific neurological (such as neuropsychiatric) disorders. Construction of three-dimensional (3D) bioprinted neural tissues from native human-derived stem cells (e.g., neural stem cells) and human pluripotent stem cells (e.g., induced pluripotent) in particular is appreciably impacting research and conceivably clinical translation. Given the ability to artificially and favorably regulate a cell's survival and behavior by manipulating its biophysical environment, careful consideration of the printing technique, supporting biomaterial and specific exogenously delivered stimuli, is both required and advantageous. By doing so, there exists an opportunity, more than ever before, to engineer advanced and precise tissue analogs that closely recapitulate the morphological and functional elements of natural tissues (healthy or diseased). Importantly, the application of electrical stimulation as a method of enhancing printed tissue development in vitro, including neuritogenesis, synaptogenesis, and cellular maturation, has the added advantage of modeling both traditional and new stimulation platforms, toward improved understanding of efficacy and innovative electroceutical development and application.

High Betrayal Child Sexual Abuse and Hallucinations: A Test of an Indirect Effect of Dissociation

Though hallucinations traditionally have been conceptualized as a central feature of psychosis, some hallucinations may be dissociative, with dissociation potentially contributing to hallucinations. Childhood trauma has been linked with dissociation and hallucinations. Betrayal trauma theory distinguishes abusive experiences based on closeness to the perpetrator. In the current study, we examined the indirect effect of dissociation on the relationship between high betrayal child sexual abuse (perpetrated by a close other) and hallucinations. Participants (N = 192) from a northwestern university in the United States completed self-report measures online assessing history of high betrayal child sexual abuse and current dissociation and hallucinations. Bootstrapping analyses indicated a significant indirect effect of high betrayal child sexual abuse on hallucinations through dissociation, 95% Confidence Interval (.16, .66). Through betrayal trauma theory, this study provides a non-pathologizing framework for understanding how dissociation and hallucinations may develop as natural reactions to the harm inherent in child sexual abuse perpetrated by a close other. These findings have clinical implications for relational models of healing for trauma survivors who are distressed by dissociation and hallucinations.

How to Use the H1 Deep Transcranial Magnetic Stimulation Coil for Conditions Other than Depression

Deep transcranial magnetic stimulation (dTMS) is a relatively new technique that uses different coils for the treatment of different neuropathologies. The coils are made of soft copper windings in multiple planes that lie adjacent to the skull. They are located within a special helmet so that their magnetic fields combine and improve depth penetration. The H1 dTMS coil is designed to stimulate bilateral prefrontal cortices with greater effective stimulation over the left than the right. By positioning the left side of the coil close to the left dorsolateral prefrontal cortex (DLPFC), the H1 coil was used in a multisite study, leading to FDA approval for treatment-resistant depression. In this same position, the H1 coil was also explored as a possible treatment for negative symptoms of schizophrenia, bipolar depression, and migraine. When moved to different positions over the subject's skull, the H1 coil was also explored as a possible treatment for other conditions. Such manipulation of the H1 coil was demonstrated for PTSD and alcohol dependence by positioning it over the medial prefrontal cortex (mPFC), for anxiety by positioning it over the right prefrontal cortex (rPFC), for auditory hallucinations and tinnitus by positioning it over the temporoparietal junction (TPJ), and for Parkinson's and fatigue from multiple sclerosis (MS) by positioning it over the motor cortex (MC) and PFC. Corresponding electrical field diagrams measured with an oscilloscope through a saline-filled head are included.

Brain connectivity and auditory hallucinations: In search of novel noninvasive brain stimulation therapeutic approaches for schizophrenia

Auditory verbal hallucinations (AVH) are among the most characteristic symptoms of schizophrenia and have been linked to likely disturbances of structural and functional connectivity within frontal, temporal, parietal and subcortical networks involved in language and auditory functions. Resting-state functional magnetic resonance imaging (fMRI) has shown that alterations in the functional connectivity activity of the default-mode network (DMN) may also subtend hallucinations. Noninvasive neurostimulation techniques such as repetitive transcranial magnetic stimulation (rTMS) have the ability to modulate activity of targeted cortical sites and their associated networks, showing a high potential for modulating altered connectivity subtending schizophrenia. Notwithstanding, the clinical benefit of these approaches remains weak and variable. Further studies in the field should foster a better understanding concerning the status of networks subtending AVH and the neural impact of rTMS in relation with symptom improvement. Additionally, the identification and characterization of clinical biomarkers able to predict response to treatment would be a critical asset allowing better care for patients with schizophrenia.

Deep transcranial magnetic stimulation (dTMS) - beyond depression

INTRODUCTION

Deep transcranial magnetic stimulation (dTMS) utilizes different H-coils to study and treat a variety of psychiatric and neurological conditions with identifiable brain targets. The availability of this technology is dramatically changing the practice of psychiatry and neurology as it provides a safe and effective way to treat even drug-resistant patients. However, up until now, no effort was made to summarize the different types of H-coils that are available, and the conditions for which they were tested. Areas covered: Here we assembled all peer reviewed publication that used one of the H-coils, together with illustrations of the effective field they generate within the brain. Currently, the technology has FDA clearance for depression and European clearance for additional disorders, and multi-center trials are exploring its safety and effectiveness for OCD, PTSD, bipolar depression and nicotine addiction. Expert commentary: Taken together with positive results in smaller scale experiments, dTMS coils represent a non-invasive way to manipulate pathological activity in different brain structures and circuits. Advances in stimulation and imaging methods can now lead to efficacious and logical treatments. This should reduce the stigma associated with mental disorders, and improve access to psychiatric treatment.

Modelling of the Electric Field Distribution in Deep Transcranial Magnetic Stimulation in the Adolescence, in the Adulthood, and in the Old Age

In the last few years, deep transcranial magnetic stimulation (dTMS) has been used for the treatment of depressive disorders, which affect a broad category of people, from adolescents to aging people. To facilitate its clinical application, particular shapes of coils, including the so-called Hesed coils, were designed. Given their increasing demand and the lack of studies which accurately characterize their use, this paper aims to provide a picture of the distribution of the induced electric field in four realistic human models of different ages and gender. In detail, the electric field distributions were calculated by using numerical techniques in the brain structures potentially involved in the progression of the disease and were quantified in terms of both amplitude levels and focusing power of the distribution. The results highlight how the chosen Hesed coil (H7 coil) is able to induce the maxima levels of E mainly in the prefrontal cortex, particularly for the younger model. Moreover, growing levels of induced electric fields with age were found by going in deep in the brain, as well as a major capability to penetrate in the deepest brain structures with an electric field higher than 50%, 70%, and 90% of the peak found in the cortex.

Repetitive transcranial magnetic stimulation for hallucination in schizophrenia spectrum disorders: A meta-analysis

OBJECTIVE

This study assessed the efficacy and tolerability of repetitive transcranial magnetic stimulation for treatment of auditory hallucination of patients with schizophrenia spectrum disorders.

DATA SOURCES

Online literature retrieval was conducted using PubMed, ISI Web of Science, EMBASE, Medline and Cochrane Central Register of Controlled Trials databases from January 1985 to May 2012. Key words were "transcranial magnetic stimulation", "TMS", "repetitive transcranial magnetic stimulation", and "hallucination".

STUDY SELECTION

Selected studies were randomized controlled trials assessing therapeutic efficacy of repetitive transcranial magnetic stimulation for hallucination in patients with schizophrenia spectrum disorders. Experimental intervention was low-frequency repetitive transcranial magnetic stimulation in left temporoparietal cortex for treatment of auditory hallucination in schizophrenia spectrum disorders. Control groups received sham stimulation.

MAIN OUTCOME MEASURES

The primary outcome was total scores of Auditory Hallucinations Rating Scale, Auditory Hallucination Subscale of Psychotic Symptom Rating Scale, Positive and Negative Symptom Scale-Auditory Hallucination item, and Hallucination Change Scale. Secondary outcomes included response rate, global mental state, adverse effects and cognitive function.

RESULTS

Seventeen studies addressing repetitive transcranial magnetic stimulation for treatment of schizophrenia spectrum disorders were screened, with controls receiving sham stimulation. All data were completely effective, involving 398 patients. Overall mean weighted effect size for repetitive transcranial magnetic stimulation versus sham stimulation was statistically significant (MD = -0.42, 95%CI: -0.64 to -0.20, P = 0.000 2). Patients receiving repetitive transcranial magnetic stimulation responded more frequently than sham stimulation (OR = 2.94, 95%CI: 1.39 to 6.24, P = 0.005). No significant differences were found between active repetitive transcranial magnetic stimulation and sham stimulation for positive or negative symptoms. Compared with sham stimulation, active repetitive transcranial magnetic stimulation had equivocal outcome in cognitive function and commonly caused headache and facial muscle twitching.

CONCLUSION

Repetitive transcranial magnetic stimulation is a safe and effective treatment for auditory hallucination in schizophrenia spectrum disorders.

Review of the efficacy of transcranial magnetic stimulation for auditory verbal hallucinations

With an increase of the number of studies exploring repetitive transcranial magnetic stimulation (rTMS) for the treatment of auditory verbal hallucinations (AVH), an update is provided on the efficacy of different paradigms. A literature search was performed from 1966 through April 2013. Twenty-five randomized controlled trials using the severity of AVH or psychosis as outcome measures were included. Standardized mean weighted effect sizes were computed; a qualitative review of the literature was performed to assess the effects of various rTMS paradigms. rTMS versus sham treatment for AVH yielded a mean weighted effect size of .44. No significant mean weighted effect size was found for the severity of psychosis (i.e., .21). For patients with medication-resistant AVH, the mean weighted effect size was .45. rTMS applied at the left temporoparietal area with a frequency of 1 Hz yielded a moderate mean weighted effect size of .63, indicating superiority of this paradigm. Various other paradigms failed to show superior effects. rTMS applied at the right temporoparietal area was not superior to sham treatment. rTMS, especially when applied at the left temporoparietal area with a frequency of 1 Hz, is effective for the treatment of AVH, including in patients with medication-resistant AVH. The results for other rTMS paradigms are disappointing thus far. A next step should be to explore the effects of rTMS in medication-free individuals, for example, during the initial phases of psychosis, and in patients with diagnoses other than schizophrenia who do not have comorbid psychotic symptoms.

Translational strategies for therapeutic development in nicotine addiction: rethinking the conventional bench to bedside approach

Tobacco produces an impressive burden of disease resulting in premature death in half of users. Despite effective smoking cessation medications (nicotine replacement therapies, bupropion and varenicline), there is a very high rate of relapse following quit attempts. The use of efficient strategies for the development of novel treatments is a necessity. A 'bench to bedside strategy' was initially used to develop cannabinoid CB1 receptor antagonists for the treatment of nicotine addiction. Unfortunately, after being tested on experimental animals, what seemed to be an interesting approach for the treatment of nicotine addiction resulted in serious unwanted side effects when tested in humans. Current research is focusing again on pre-clinical models in an effort to eliminate unwanted side effects while preserving the initially observed efficacy. A 'bed side to bench strategy' was used to study the role of the insula (part of the frontal cortex) in nicotine addiction. This line of research started based on clinical observations that patients suffering stroke-induced lesions to the insula showed a greater likelihood to report immediate smoking cessation without craving or relapse. Subsequently, animal models of addiction are used to explore the role of insula in addiction. Due to the inherent limitations existing in clinical versus preclinical studies, the possibility of close interaction between both models seems to be critical for the successful development of novel therapeutic strategies for nicotine dependence.

Coil design considerations for deep transcranial magnetic stimulation

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.

Deep transcranial magnetic stimulation for treatment-resistant bipolar depression: a case report of acute and maintenance efficacy

Deep Transcranial Magnetic Stimulation (dTMS) is currently being evaluated as a possible treatment for several neuropsychiatric disorders and has been demonstrated as a safe and effective procedure. This case presents a patient with bipolar depression that has been treated with 20 daily consecutive dTMS sessions and with one dTMS session every 2 weeks for the following 3 months. Depressive symptoms improved rapidly and response was maintained during the next 6 months; cognitive performances also improved. This report suggests that add-on dTMS may help overcoming drug-resistance in bipolar depression and protect from subsequent bipolar episodes of any polarity.

Brain stimulation in psychiatry: methods and magnets, patients and parameters

PURPOSE OF REVIEW

Electromagnetic brain stimulation is performed in various ways in psychiatric settings for the treatment of a variety of psychiatric disorders.

RECENT FINDINGS

Transcranial direct current stimulation is a comparatively simple procedure. The available results warrant optimism regarding the future of this therapeutic approach in psychiatry. Multicentre studies of repetitive transcranial magnetic stimulation demonstrate a moderate treatment effect in depression. Theta burst stimulation and deep brain repetitive transcranial magnetic stimulation represent innovative promising developments. The invasiveness of deep brain stimulation still causes this method to be one of the last resorts, even though promising results in severely disordered patients have been published.

SUMMARY

In our view, the field of brain stimulation will be rapidly moving forward in the near future and will establish itself as one more of the 'tools of the trade' in psychiatric therapeutic practice.

The treatment of hallucinations in schizophrenia spectrum disorders

This article reviews the treatment of hallucinations in schizophrenia. The first treatment option for hallucinations in schizophrenia is antipsychotic medication, which can induce a rapid decrease in severity. Only 8% of first-episode patients still experience mild to moderate hallucinations after continuing medication for 1 year. Olanzapine, amisulpride, ziprasidone, and quetiapine are equally effective against hallucinations, but haloperidol may be slightly inferior. If the drug of first choice provides inadequate improvement, it is probably best to switch medication after 2-4 weeks of treatment. Clozapine is the drug of choice for patients who are resistant to 2 antipsychotic agents. Blood levels should be above 350-450 μg/ml for maximal effect. For relapse prevention, medication should be continued in the same dose. Depot medication should be considered for all patients because nonadherence is high. Cognitive-behavioral therapy (CBT) can be applied as an augmentation to antipsychotic medication. The success of CBT depends on the reduction of catastrophic appraisals, thereby reducing the concurrent anxiety and distress. CBT aims at reducing the emotional distress associated with auditory hallucinations and develops new coping strategies. Transcranial magnetic stimulation (TMS) is capable of reducing the frequency and severity of auditory hallucinations. Several meta-analyses found significantly better symptom reduction for low-frequency repetitive TMS as compared with placebo. Consequently, TMS currently has the status of a potentially useful treatment method for auditory hallucinations, but only in combination with state of the art antipsychotic treatment. Electroconvulsive therapy (ECT) is considered a last resort for treatment-resistant psychosis. Although several studies showed clinical improvement, a specific reduction in hallucination severity has never been demonstrated.

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

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.

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

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.

Neuroimaging and neuromodulation: complementary approaches for identifying the neuronal correlates of tinnitus

An inherent limitation of functional imaging studies is their correlational approach. More information about critical contributions of specific brain regions can be gained by focal transient perturbation of neural activity in specific regions with non-invasive focal brain stimulation methods. Functional imaging studies have revealed that tinnitus is related to alterations in neuronal activity of central auditory pathways. Modulation of neuronal activity in auditory cortical areas by repetitive transcranial magnetic stimulation (rTMS) can reduce tinnitus loudness and, if applied repeatedly, exerts therapeutic effects, confirming the relevance of auditory cortex activation for tinnitus generation and persistence. Measurements of oscillatory brain activity before and after rTMS demonstrate that the same stimulation protocol has different effects on brain activity in different patients, presumably related to interindividual differences in baseline activity in the clinically heterogeneous study cohort. In addition to alterations in auditory pathways, imaging techniques also indicate the involvement of non-auditory brain areas, such as the fronto-parietal "awareness" network and the non-tinnitus-specific distress network consisting of the anterior cingulate cortex, anterior insula, and amygdale. Involvement of the hippocampus and the parahippocampal region putatively reflects the relevance of memory mechanisms in the persistence of the phantom percept and the associated distress. Preliminary studies targeting the dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and the parietal cortex with rTMS and with transcranial direct current stimulation confirm the relevance of the mentioned non-auditory networks. Available data indicate the important value added by brain stimulation as a complementary approach to neuroimaging for identifying the neuronal correlates of the various clinical aspects of tinnitus.

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

BACKGROUND

Various transcranial magnetic stimulation (TMS) coil designs are available or have been proposed. However, key coil characteristics such as electric field focality and attenuation in depth have not been adequately compared. Knowledge of the coil focality and depth characteristics can help TMS researchers and clinicians with coil selection and interpretation of TMS studies.

OBJECTIVE

To quantify the electric field focality and depth of penetration of various TMS coils.

METHODS

The electric field distributions induced by 50 TMS coils were simulated in a spherical human head model using the finite element method. For each coil design, we quantified the electric field penetration by the half-value depth, d(1/2), and focality by the tangential spread, S(1/2), defined as the half-value volume (V(1/2)) divided by the half-value depth, S(1/2) = V(1/2)/d(1/2).

RESULTS

The 50 TMS coils exhibit a wide range of electric field focality and depth, but all followed a depth-focality tradeoff: coils with larger half-value depth cannot be as focal as more superficial coils. The ranges of achievable d(1/2) are similar between coils producing circular and figure-8 electric field patterns, ranging 1.0-3.5 cm and 0.9-3.4 cm, respectively. However, figure-8 field coils are more focal, having S(1/2) as low as 5 cm(2) compared to 34 cm(2) for circular field coils.

CONCLUSIONS

For any coil design, the ability to directly stimulate deeper brain structures is obtained at the expense of inducing wider electrical field spread. Novel coil designs should be benchmarked against comparison coils with consistent metrics such as d(1/2) and S(1/2).

Schizophrenia as a disorder of social communication

Evidence is reviewed for the existence of a core system for moment-to-moment social communication that is based on the perception of dynamic gestures and other social perceptual processes in the temporal-parietal occipital junction (TPJ), including the posterior superior temporal sulcus (PSTS) and surrounding regions. Overactivation of these regions may produce the schizophrenic syndrome. The TPJ plays a key role in the perception and production of dynamic social, emotional, and attentional gestures for the self and others. These include dynamic gestures of the body, face, and eyes as well as audiovisual speech and prosody. Many negative symptoms are characterized by deficits in responding within these domains. Several properties of this system have been discovered through single neuron recording, brain stimulation, neuroimaging, and the study of neurological impairment. These properties map onto the schizophrenic syndrome. The representation of dynamic gestures is multimodal (auditory, visual, and tactile), matching the predominant hallucinatory categories in schizophrenia. Inherent in the perceptual signal of gesture representation is a computation of intention, agency, and anticipation or expectancy (for the self and others). The neurons are also tuned or biased to rapidly detect threat-related emotions. I review preliminary evidence that overactivation of this system can result in schizophrenia.

Insights into hallucinations in schizophrenia: novel treatment approaches

Novel strategies are needed in the treatment of hallucinations as a subgroup of patients with pathological hallucinations (>30%) do not respond to antipsychotics or are not compliant with medication. We review recently developed biological and cognitive treatments. Repetitive transcranial magnetic stimulation concerns neuromodulation targeted at aberrant activity in regions shown to be hyperactive in neuroimaging studies. Repetitive transcranial magnetic stimulation has been shown to reduce auditory hallucinations in several studies. However, not all studies have confirmed such effects, and a number of questions remain. With regard to cognitive therapeutic approaches, new proposals include attention training, acceptance and commitment therapy, and competitive memory training. After a brief discussion of these approaches, we take stock of recent advances and discuss avenues for future research.

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

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is emerging as a valuable therapeutic and diagnostic tool. rTMS appears particularly promising for disorders characterized by positive sensory phenomena that are attributable to alterations in sensory cortical excitability. Among these are tinnitus, auditory and visual hallucinations, and pain syndromes.

OBJECTIVE

Despite studies addressing rTMS efficacy in suppression of positive sensory symptoms, the safety of stimulation of potentially hyperexcitable cortex has not been fully addressed. We performed a systematic literature review and metaanalysis to describe the rTMS safety profile in these disorders.

METHODS

Using the PubMed database, we performed an English-language literature search from January 1985 to April 2011 to review all pertinent publications. Per study, we noted and listed pertinent details. From these data we also calculated a crude per-subject risk for each adverse event.

RESULTS

One hundred six publications (n = 1815) were identified with patients undergoing rTMS for pathologic positive sensory phenomena. Adverse events associated with rTMS were generally mild and occurred in 16.7% of subjects. Seizure was the most serious adverse event, and occurred in three patients with a 0.16% crude per-subject risk. The second most severe adverse event involved aggravation of sensory phenomena, occurring in 1.54%.

CONCLUSIONS

The published data suggest rTMS for the treatment or diagnosis of pathologic positive sensory phenomena appears to be a relatively safe and well-tolerated procedure. However, published data are lacking in systematic reporting of adverse events, and safety risks of rTMS in these patient populations will have to be addressed in future prospective trials.

Is tinnitus an acoasm?

Tinnitus and unspecific auditory hallucinations generally known as acoasms arise from identical or at least similar cerebral structures. Both phenomena can be interpreted as signs of an over activation of neuronal networks. Several pieces of evidence to underline this hypothesis as well as its implications are discussed. It is even speculated that both clinical entities might profit from treatment strategies that are normally employed for treatment of the other.