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

Department of Clinical Neurophysiology, Georg-August University, Robert Koch Strasse 40, 37075 Göttingen, Germany.
European Journal of Neuroscience (Impact Factor: 3.18). 04/2008; 27(5):1292-300. DOI: 10.1111/j.1460-9568.2008.06090.x
Source: PubMed


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, caused by activity modulation of interconnected areas. However, this has not yet been tested electrophysiologically. We aimed to study whether premotor tDCS can modify the excitability of the ipsilateral M1 via cortico-cortical connectivity. Sixteen subjects received cathodal and anodal tDCS of the PM and eight subjects of the dorsolateral prefrontal cortex. Premotor anodal, but not premotor cathodal or prefrontal tDCS, modified selectively short intracortical inhibition/intracortical facilitation (SICI/ICF), while motor thresholds, single test-pulse motor-evoked potential and input-output curves were stable throughout the experiments. Specifically, anodal tDCS decreased intracortical inhibition and increased paired-pulse excitability. The selective influence of premotor tDCS on intracortical excitability of the ipsilateral M1 suggests a connectivity-driven effect of tDCS on remote cortical areas. Moreover, this finding indirectly substantiates the efficacy of tDCS to modulate premotor excitability, which might be of interest for applications in diseases accompanied by pathological premotor activity.

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    • "Across all patients, the motor hotspot resided in the primary motor cortex (x: 40.27 ± 4.1 y: 15.5 ± 4.1 z: 56 ± 4.6) and the center of the tDCS electrode resided in the premotor cortex (x: 37.1 ± 4.91 y: –6.91 ± 9.32 z: 52.6 ± 5.1). Previous work suggests this location targets dorsal PMC but is expected to affect SMA as well since it is only 1–1.5 cm medial (Boros et al., 2008). As such we label these areas together as 'higher motor.' "
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    ABSTRACT: Purpose: To demonstrate, in a proof-of-concept study, whether potentiating ipsilesional higher motor areas (premotor cortex and supplementary motor area) augments and accelerates recovery associated with constraint induced movement. Methods: In a randomized, double-blinded pilot clinical study, 12 patients with chronic stroke were assigned to receive anodal transcranial direct current stimulation (tDCS) (n = 6) or sham (n = 6) to the ipsilesional higher motor areas during constraint-induced movement therapy. We assessed functional and neurophysiologic outcomes before and after 5 weeks of therapy. Results: Only patients receiving tDCS demonstrated gains in function and dexterity. Gains were accompanied by an increase in excitability of the contralesional rather than the ipsilesional hemisphere. Conclusions: Our proof-of-concept study provides early evidence that stimulating higher motor areas can help recruit the contralesional hemisphere in an adaptive role in cases of greater ipsilesional injury. Whether this early evidence of promise translates to remarkable gains in functional recovery compared to existing approaches of stimulation remains to be confirmed in large-scale clinical studies that can reasonably dissociate stimulation of higher motor areas from that of the traditional primary motor cortices.
    Restorative neurology and neuroscience 10/2015; DOI:10.3233/RNN-150574 · 2.49 Impact Factor
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    • "Several studies as well as clinical implications have shown that tDCS might modulate cortical excitability in the human motor cortex (Boggio, Castro, et al., 2006; Boggio et al., 2007; Boros, Poreisz, Münchau, Paulus, & Nitsche, 2008), visual cortex (Accornero, Li Voti, La Riccia, & Gregori, 2007; Antal et al., 2004), and parietal cortex (Sparing et al., 2009; Stone & Tesche, 2009; Brunoni et al., 2012). In addition to motor and visual learning tasks, tDCS has been effectively used in memory studies, especially working memory (Boggio, Ferrucci, et al., 2006; Ferrucci, Marceglia, et al., 2008; Fregni et al., 2005; Jo et al., 2009), episodic memory, and declarative memory (Javadi & Walsh, 2012; Marshall , Mölle, Hallschmid, & Born, 2004). "
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    ABSTRACT: Objective: Recent studies on treating obsessive compulsive disorder (OCD) have investigated noninvasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) to improve patients’ impaired emotion and cognition. However, such experiments have yielded mixed results, especially with respect to cognition. This study aimed to investigate whether anodal and cathodal tDCS applied over the dorsolateral prefrontal cortex (DLPFC) would improve decision making and reduce obsession symptoms in patients with OCD. Methods: the current study is analysis of variance. In this regard, 20 patients with obsessive compulsive disorder (n=20) were randomly assigned to receive either experimental (active) or control (sham) tDCS. To measure cognitive functions, the participants underwent a series of decision making neuropsychological tasks; to measure obsession symptoms, the Yale-brown obsessive compulsive and Beck anxiety scale (BAI) were used. The parameters of active tDCS included administration of 2 mA for 20 minutes per day for 15 consecutive days, anode electrode over the right DLPFC (F4), and cathode electrode over the left DLPFC (F3) region. Results: After 10 sessions of anodal and cathodal tDCS, patients showed significant improvement in decision making tasks. The same results were observed for obsession symptoms. Conclusion: The data were analyzed by SPSS 18.0.0 software, using analysis of variance methods.This study demonstrated that anodal tDCS over left DLPFC, concurrent with cathodal tDCS over right DLPFC, improved cognitive impairment and reduced obsession symptoms in patients with OCD.
    • "It is possible that the effects of tDCS over PM were mediated by a stimulation-evoked increase in M1 excitability, which has been shown to contain neurons with mirrorlike properties in non-human primates (Tkach et al., 2007; Dushanova & Donoghue, 2010) and so may be engaged in observational as well as active motor learning. Although anodal tDCS over PM does not affect overall M1 excitability assessed by TMS thresholds for motor-evoked potentials or by TMS input/output functions, it does decrease short-interval intracortical inhibition and increase intracortical facilitation in M1, effects argued to result from activation of physiological connections from PM to M1 (Boros et al., 2008). "
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    ABSTRACT: Motor skills, including complex movement sequences, can be acquired by observing a model without physical practice of the skill, a phenomenon known as observational learning. Observational learning of motor skills engages the same memory substrate as physical practice, and is thought to be mediated by the action observation network, a bilateral fronto-parietal circuit with mirror-like properties. We examined the effects of anodal tDCS over premotor cortex, a key node of the action observation network, with on observational learning of a serial response time task. Results showed that anodal tDCS during observation of the to-be-learned sequence facilitated reaction times in the subsequent behavioral test. The study provides evidence that increasing excitability of the AON during observation can facilitate later motor skill acquisition. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    European Journal of Neuroscience 04/2015; 41(12). DOI:10.1111/ejn.12916 · 3.18 Impact Factor
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