Effects of brain polarization on reaction times and pinch force in chronic stroke

Hummel, Friedhelm C.; Voller, Bernhard; Celnik, Pablo; Flöel, Agnes; Giraux, Pascal; Gerloff, Christian; Cohen, Leonardo G.

doi:10.1186/1471-2202-7-73

Cited by 195 publications

(88 citation statements)

References 52 publications

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“…It might be that tDCS does not further increase voluntary activation, suggesting a ceiling effect at corticospinal levels. It has been documented that when there is little or no potential for improvement in a motor function, tDCS does not further enhance that function, whereas when potential for improvement in function exists, tDCS has the capacity to enhance that function (Hummel et al 2006). This might explain why tDCS produced no change in the muscle function of the healthy young male participants in our study.…”

Section: Discussionmentioning

confidence: 98%

Effect of transcranial direct current stimulation on elbow flexor maximal voluntary isometric strength and endurance

Kan

Dundas

Nosaka

2013

Appl. Physiol. Nutr. Metab.

109

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The effects of transcranial direct current stimulation (tDCS) on maximal voluntary isometric contraction (MVC) strength and the time to failure (TTF) in an isometric (30% MVC) muscle endurance test of the elbow flexors were investigated. Fifteen men (mean age, 27.7 ± 8.4 years) were tested for MVC strength and TTF 2 times, separated by a 60-min rest. During the last 10 min of the rest period, 1 of 2 tDCS treatments or 1 sham intervention session was administered, in a randomized order, with 1 week between sessions. In the tDCS intervention, a 2 mA direct current was delivered for 10 min through an anode placed on the scalp, overlying the right motor cortical representation of the left arm; a cathode was secured over the right shoulder. In the sham intervention, the current was delivered for the first 30 s only. No significant differences between the first and second tDCS sessions were evident for MVC strength or TTF. For MVC strength (baseline, 66.0 ± 11.4 Nm), postintervention measures decreased by 5.9% ± 4.2% (p < 0.05), but no significant difference in the changes was evident between tDCS and sham sessions. TTF did not change significantly from preintervention (309.2 ± 91.6 s) to postintervention (327.2 ± 128.5 s), and there was no significant difference between interventions. It was concluded that the tDCS intervention did not affect muscle function, perhaps because of ceiling effects, in which the intervention does not enhance muscle function further when muscle function is already maximal.

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Section: Discussionmentioning

confidence: 98%

Effect of transcranial direct current stimulation on elbow flexor maximal voluntary isometric strength and endurance

Kan

Dundas

Nosaka

2013

Appl. Physiol. Nutr. Metab.

109

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“…Many studies have found improvements in motor function in stroke patients as measured by clinical scales or the JTT (Fregni et al, 2005; Hummel et al, 2005; Lindenberg et al, 2010; Mahmoudi et al, 2011; Khedr et al, 2013; Lefebvre et al, 2013) and an increase in pinch or grip force and a decrease in reaction times (Hummel et al, 2006; Stagg et al, 2012; Lefebvre et al, 2013). The improvement in reaction time with the ipsilesional stimulation protocol was correlated with the change in movement related activity under the anodal electrode (M1) and in the ipsilesional premotor cortex (Stagg et al, 2012).…”

Section: Application Of the Three Principles Of Polarizationmentioning

confidence: 99%

“…Decrease in GABA concentration is probably helpful for motor-related activity in the ipsilesional cortex (Clarkson et al, 2010). An increase in spontaneous/evoked firing rates might also drive some of the effects such as increase in pinch force (Hummel et al, 2006) and the increase in movement-related activity (Stagg et al, 2012). The long-lasting effect of tDCS on motor function is likely due to the after-effect of tDCS and its ability to engrave new firing patterns in memory.…”

Section: Application Of the Three Principles Of Polarizationmentioning

confidence: 99%

Electrifying the motor engram: effects of tDCS on motor learning and control

Xivry

Shadmehr

2014

Exp Brain Res

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Learning to control our movements accompanies neuroplasticity of motor areas of the brain. The mechanisms of neuroplasticity are diverse and produce what is referred to as the motor engram, i.e. the neural trace of the motor memory. Transcranial direct current stimulation (tDCS) alters the neural and behavioral correlates of motor learning, but its precise influence on the motor engram is unknown. In this review, we summarize the effects of tDCS on neural activity and suggest a few key principles: 1) firing rates are increased by anodal polarization and decreased by cathodal polarization, 2) anodal polarization strengthens newly formed associations, and 3) polarization modulates the memory of new/preferred firing patterns. With these principles in mind, we review the effects of tDCS on motor control, motor learning, and clinical applications. The increased spontaneous and evoked firing rates may account for the modulation of dexterity in non-learning tasks by tDCS. The facilitation of new association may account for the effect of tDCS on learning in sequence tasks while the ability of tDCS to strengthen memories of new firing patterns may underlie the effect of tDCS on consolidation of skills. We then describe the mechanisms of neuroplasticity of motor cortical areas and how they might be influenced by tDCS. We end with current challenges for the fields of brain stimulation and motor learning.

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“…However, they may produce similar effects that may include increased excitability or normalization of inhibition, which coincide with improvements in motor behavior. 13 Methods of priming the motor cortex that are most relevant to rehabilitation include: (1) stimulation-based priming; 14-22 (2) motor imagery and action observation; 23-28 (3) manipulation of sensory input; 29-31 (4) movement-based priming; 7, 32-36 and (5) pharmacology-based priming. 37 Studies examining priming for the primary motor cortex (M1) are increasing in number.…”

Section: Introductionmentioning

confidence: 99%

Motor Priming in Neurorehabilitation

Stoykov

Madhavan

2015

Journal of Neurologic Physical Therapy

132

109

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Priming is a type of implicit learning wherein a stimulus prompts a change in behavior. Priming has been long studied in the field of psychology. More recently, rehabilitation researchers have studied motor priming as a possible way to facilitate motor learning. For example, priming of the motor cortex is associated with changes in neuroplasticity that are associated with improvements in motor performance. Of the numerous motor priming paradigms under investigation, only a few are practical for the current clinical environment, and the optimal priming modalities for specific clinical presentations are not known. Accordingly, developing an understanding of the various types of motor priming paradigms and their underlying neural mechanisms is an important step for therapists in neurorehabilitation. Most importantly, an understanding of the methods and their underlying mechanisms is essential for optimizing rehabilitation outcomes. The future of neurorehabilitation is likely to include these priming methods, which are delivered prior to or in conjunction with primary neurorehabilitation therapies. In this Special Interest article we discuss those priming paradigms that are supported by the greatest amount of evidence including: (i) stimulation-based priming, (ii) motor imagery and action observation, (iii) sensory priming, (iv) movement-based priming, and (v) pharmacological priming.

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Effects of brain polarization on reaction times and pinch force in chronic stroke

Cited by 195 publications

References 52 publications

Effect of transcranial direct current stimulation on elbow flexor maximal voluntary isometric strength and endurance

Effect of transcranial direct current stimulation on elbow flexor maximal voluntary isometric strength and endurance

Electrifying the motor engram: effects of tDCS on motor learning and control

Motor Priming in Neurorehabilitation

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