Three-Dimensional Distribution of the Electric Field Induced in the Brain by Transcranial Magnetic Stimulation Using Figure-8 and Deep H-Coils

Tel Aviv University, Tell Afif, Tel Aviv, Israel
Journal of Clinical Neurophysiology (Impact Factor: 1.43). 03/2007; 24(1):31-8. DOI: 10.1097/WNP.0b013e31802fa393
Source: PubMed


The H-coils are a novel development in transcranial magnetic stimulation (TMS), designed to achieve effective stimulation of deep neuronal regions without inducing unbearable fields cortically, thus broadly expanding the potential feasibility of TMS for research and for treating various neurologic disorders. This study compared the field distribution of two H-coil versions, termed H1 and H2, and of a standard figure-of-eight coil. Three-dimensional electrical field distributions of the H1 and H2-coils, designed for effective stimulation of prefrontal regions, and of a standard figure-8 coil, were measured in a head model filled with physiologic saline solution. With stimulator output at 120% of the hand motor threshold, suprathreshold field is induced by the H1-coil at lateral and medial frontal regions at depths of up to 4 to 5 cm, and by the H2-coil at medial prefrontal regions up to 2 to 3 cm, and at lateral frontal regions up to 5 to 6 cm. The figure-8 coil induced suprathreshold field focally under the coil's central segment, at depths of up to 1.5 cm. The ability of the H-coils to stimulate effectively deeper neuronal structures is obtained at the cost of a wider electrical field distribution in the brain. However, the H-coils enable simultaneous stimulation of several brain regions, whereas the depth penetration in each region can be controlled either by adjusting the stimulator output, and/or by varying the distance between various coil elements and the skull.

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Available from: Yiftach Roth, Sep 29, 2015
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    • "This limitation led to the newly developed deep TMS (deepTMS) H-coil [33] which is able to safely modulate cortical excitability of deeper neural circuits [32] [33]. Similar to standard TMS, these deepTMS techniques target hypoactivity within the DLPFC [32] [33] [47] while stimulating deeper cortical structures within the frontoparietal-limbic circuitry in treating depressive disorders [45] [46] [48] [49]. Therefore, delivery of repetitive TMS (rTMS) to the DLPFC targets the same compromised circuitry which correlates with impaired attentional control in MDD [6] [8] [10]. "
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    ABSTRACT: While Major Depressive Disorder (MDD) is primarily characterized by mood disturbances, impaired attentional control is increasingly identified as a critical feature of depression. Deep transcranial magnetic stimulation (deepTMS), a noninvasive neuromodulatory technique, can modulate neural activity and induce neuroplasticity changes in brain regions recruited by attentional processes. This study examined whether acute and long-term high-frequency repetitive deepTMS to the dorsolateral prefrontal cortex (DLPFC) can attenuate attentional deficits associated with MDD. Twenty-one MDD patients and 26 matched control subjects (CS) were administered the Beck Depression Inventory and the Sustained Attention to Response Task (SART) at baseline. MDD patients were readministered the SART and depressive assessments following a single session (í µí±› = 21) and after 4 weeks (í µí±› = 13) of high-frequency (20 Hz) repetitive deepTMS applied to the DLPFC. To control for the practice effect, CS (í µí±› = 26) were readministered the SART a further two times. The MDD group exhibited deficits in sustained attention and cognitive inhibition. Both acute and long-term high-frequency repetitive frontal deepTMS ameliorated sustained attention deficits in the MDD group. Improvement after acute deepTMS was related to attentional recovery after long-term deepTMS. Longer-term improvement in sustained attention was not related to antidepressant effects of deepTMS treatment.
    Full-text · Article · Oct 2015 · Neural Plasticity
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    • "For dTMS sessions we used Brainsway's H1 coil deep TMS System (Brainsway, Har Hotzvim, Jerusalem, Israel). The H1 coil is designed to elicit neuronal activation in medial and lateral prefrontal regions, including the orbitofrontal cortex, with a preference for the left hemisphere (Roth et al., 2007). H1 coils were positioned over patient's scalp. "
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    ABSTRACT: Introduction: Co-occurrence of Major Depressive (MDD) and Alcohol Use Disorders (AUDs) is frequent, causing more burden than each disorder separately. Since the dorsolateral prefrontal cortex (DLPFC) is critically involved in both mood and reward and dysfunctional in both conditions, we aimed to evaluate the effects of dTMS stimulation of bilateral DLPFC with left prevalence in patients with MDD with or without concomitant AUD. Methods: Twelve MDD patients and 11 with concomitant MDD and AUD (MDD+AUD) received 20 dTMS sessions. Clinical status was assessed through the Hamilton Depression Rating Scale (HDRS) and the Clinical Global Impressions severity scale (CGIs), craving through the Obsessive Compulsive Drinking Scale (OCDS) in MDD+AUD, and functioning with the Global Assessment of Functioning (GAF). Results: There were no significant differences between the two groups in sociodemographic (age, sex, years of education and duration of illness) and baseline clinical characteristics, including scores on assessment scales. Per cent drops on HDRS and CGIs scores at the end of the sessions were respectively 62.6% and 78.2% for MDD+AUD, and 55.2% and 67.1% for MDD (p<0.001). HDRS, CGIs and GAF scores remained significantly improved after the 6-month follow-up. HDRS scores dropped significantly earlier in MDD+AUD than in MDD LIMITATIONS: The small sample size and factors inherent to site and background treatment may have affected results. Conclusions: High frequency bilateral DLPFC dTMS with left preference was well tolerated and effective in patients with MDD, with or without AUD. The antidepressant effect of dTMS is not affected by alcohol abuse in patients with depressive episodes. The potential use of dTMS for mood modulation as an adjunct to treatment in patients with a depressive episode, with or without alcohol abuse, deserves further investigation.
    Full-text · Article · Nov 2014 · Journal of Affective Disorders
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    • "A recently developed variant of TMS is deep TMS. Deep TMS coils minimize the accumulation of electrical charge on the surface of the brain and maximize the electrical field deep in the brain by the summation of separate fields projected into the skull from several different points around its periphery (Roth, Amir, Levkovitz &amp; Zangen, 2007). A review comparing the efficacy and tolerability of deepTMS, rTMS and ECT in drug-free patients with pharmaco-resistant unipolar depression confirmed the superior efficacy of ECT as the most effective treatment option after 4 weeks of therapy. "
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    ABSTRACT: Despite the fact that several interventions for major depression have proven efficacy, a substantial number of patients are or become treatment resistant to various forms of pharmacotherapy and psychotherapy. Biological interventions that directly target brain activity such as electroconvulsive therapy are used to treat these patients, but some of these interventions are unlikely to be easily accepted because of their more invasive nature or side-effects. The efficacy of non-invasive neurostimulation with a favorable side effect profile, such as repetitive Transcranial Magnetic Stimulation, could not be sufficiently demonstrated for treatment resistant depressed patients (TRD). We argue that research on the working mechanisms of these neurostimulation techniques is necessary to develop more efficient treatment protocols. After an overview of current neurostimulation approaches to treatment resistance and the introduction of a neurobiological and a cognitive framework of depression, we provide an integrative review of research on both the neurobiological and cognitive working mechanisms of neurostimulation in TRD, with a specific emphasis on the work of our lab. Thereafter, we describe our own studies and studies from other labs on new neurocognitive interventions. Finally we discuss how all this knowledge can be used to further develop new strategies to deal with treatment resistance, in combining neurostimulation and cognitive interventions.
    Preview · Article · Nov 2014 · Clinical Psychology Review
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