The Interaction With Task-induced Activity is More Important Than Polarization: A tDCS Study

Bortoletto, Marta; Pellicciari, Maria Concetta; Rodella, Claudia; Miniussi, Carlo

doi:10.1016/j.brs.2014.11.006

Cited by 121 publications

(81 citation statements)

References 51 publications

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“…In keeping with this idea, Neubert and colleagues50, combining dsTMS and diffusion-weighted magnetic resonance imaging, suggested that subcortical pathways involving the basal ganglia mediate interactions between the pIFG and contralateral M1 conducive to action reprogramming at relatively early latencies (ISI of 12 ms). Admittedly, the CS-induced modulations of MEPs at these long latencies might not be solely ascribed to direct connections between the conditioning brain site and M1, but might be based on the recruitment of larger scale CS-related brain networks involving indirect pathways5152. Our data do not provide any information about the specific pathway involved in the long-latency influence of pIFG or pre-SMA over M1 and this represents a potential limitation of our study.…”

Section: Discussionmentioning

confidence: 72%

Long-latency modulation of motor cortex excitability by ipsilateral posterior inferior frontal gyrus and pre-supplementary motor area

Fiori

Chiappini

Soriano

et al. 2016

Sci Rep

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The primary motor cortex (M1) is strongly influenced by several frontal regions. Dual-site transcranial magnetic stimulation (dsTMS) has highlighted the timing of early (<40 ms) prefrontal/premotor influences over M1. Here we used dsTMS to investigate, for the first time, longer-latency causal interactions of the posterior inferior frontal gyrus (pIFG) and pre-supplementary motor area (pre-SMA) with M1 at rest. A suprathreshold test stimulus (TS) was applied over M1 producing a motor-evoked potential (MEP) in the relaxed hand. Either a subthreshold or a suprathreshold conditioning stimulus (CS) was administered over ipsilateral pIFG/pre-SMA sites before the TS at different CS-TS inter-stimulus intervals (ISIs: 40–150 ms). Independently of intensity, CS over pIFG and pre-SMA (but not over a control site) inhibited MEPs at an ISI of 40 ms. The CS over pIFG produced a second peak of inhibition at an ISI of 150 ms. Additionally, facilitatory modulations were found at an ISI of 60 ms, with supra- but not subthreshold CS intensities. These findings suggest differential modulatory roles of pIFG and pre-SMA in M1 excitability. In particular, the pIFG –but not the pre-SMA– exerts intensity-dependent modulatory influences over M1 within the explored time window of 40-150 ms, evidencing fine-tuned control of M1 output.

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Section: Discussionmentioning

confidence: 72%

Long-latency modulation of motor cortex excitability by ipsilateral posterior inferior frontal gyrus and pre-supplementary motor area

Fiori

Chiappini

Soriano

et al. 2016

Sci Rep

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“…One aspect to consider is that there are several technical parameters from which we can choose to run an experiment and of which little is known about the consequences of their use. For example, only a few authors have considered the importance of task engagement or performance level during stimulation (e.g., Bortoletto and others 2015a; Dockery and others 2009; Hsu and others 2014; Learmonth and others 2015; Tseng and others 2012), intrasubject variability (e.g., Krause and Cohen Kadosh 2014; Li and others 2015; Wiethoff and others 2014), and the factors that influence the diffusion of the currents in the brain (Opitz and others 2015) in relation to different neuronal populations and orientations (see also Box 2 “no man’s land” hypothesis to explain nonlinear effects). Undoubtedly, the interactions of all of these important, basic elements are relevant to the final result (Li and others 2015) as outlined in Figure 1.…”

Section: Tes Good For All or Tes Not Good At All?mentioning

confidence: 99%

“…Thus, the stimulation effects will depend on the level of on-going activity (i.e., the excitability state) of the stimulated network(s). Several studies have demonstrated that tES can modulate behavior depending on the neural activity level induced by the task, even reverting the effects of the same tES type contingent on the level of network engagement (e.g., Antal and others 2004; Benwell and others 2015; Bortoletto and others 2015a; Furuya and others 2014; Hsu and others 2014; Gill and others 2015; Tseng and others 2012). …”

Section: Models Of Tes Effectsmentioning

confidence: 99%

Transcranial Electrical Stimulation

2016

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In recent years, there has been remarkable progress in the understanding and practical use of transcranial electrical stimulation (tES) techniques. Nevertheless, to date, this experimental effort has not been accompanied by substantial reflections on the models and mechanisms that could explain the stimulation effects. Given these premises, the aim of this article is to provide an updated picture of what we know about the theoretical models of tES that have been proposed to date, contextualized in a more specific and unitary framework. We demonstrate that these models can explain the tES behavioral effects as distributed along a continuum from stimulation dependent to network activity dependent. In this framework, we also propose that stochastic resonance is a useful mechanism to explain the general online neuromodulation effects of tES. Moreover, we highlight the aspects that should be considered in future research. We emphasize that tES is not an “easy-to-use” technique; however, it may represent a very fruitful approach if applied within rigorous protocols, with deep knowledge of both the behavioral and cognitive aspects and the more recent advances in the application of stimulation.

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“…The polarity of cerebellar tDCS after-effects may also depend on the pre-existing excitability state, as well as with task-induced activity, as described for cortical stimulation [69]. Elucidation of the physiological variables underlying tDCS after-effects and evidence for the existence of a cerebellar homeostatic-like plasticity would be critical areas to investigate extensively in future studies.…”

Section: Mechanisms Of Actionmentioning

confidence: 99%

Cerebellar transcranial direct current stimulation in neurological disease

et al. 2016

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Several studies have highlighted the therapeutic potential of transcranial direct current stimulation (tDCS) in patients with neurological diseases, including dementia, epilepsy, post-stroke dysfunctions, movement disorders, and other pathological conditions.Because of this technique’s ability to modify cerebellar excitability without significant side effects, cerebellar tDCS is a new, interesting, and powerful tool to induce plastic modifications in the cerebellum.In this report, we review a number of interesting studies on the application of cerebellar tDCS for various neurological conditions (ataxia, Parkinson’s disease, dystonia, essential tremor) and the possible mechanism by which the stimulation acts on the cerebellum.Study findings indicate that cerebellar tDCS is a promising therapeutic tool in treating several neurological disorders; however, this method’s efficacy appears to be limited, given the current data.

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The Interaction With Task-induced Activity is More Important Than Polarization: A tDCS Study

Cited by 121 publications

References 51 publications

Long-latency modulation of motor cortex excitability by ipsilateral posterior inferior frontal gyrus and pre-supplementary motor area

Long-latency modulation of motor cortex excitability by ipsilateral posterior inferior frontal gyrus and pre-supplementary motor area

Transcranial Electrical Stimulation

Cerebellar transcranial direct current stimulation in neurological disease

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