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Cathodal HD-tDCS on the right V5 improves motion perception in humans.

Zito GA, Senti T, Cazzoli D, Müri RM, Mosimann UP, Nyffeler T, Nef T - Front Behav Neurosci (2015)

Bottom Line: The results showed significant improvement in motion perception in the left hemifield after cathodal HD-tDCS, but not in shape perception.Sham and anodal HD-tDCS did not affect performance.The specific effect of influencing performance of visual tasks by modulating the excitability of the neurons in the visual cortex might be explained by the complexity of perceptual information needed for the tasks.

View Article: PubMed Central - PubMed

Affiliation: Gerontechnology and Rehabilitation Group, University of Bern Bern, Switzerland.

ABSTRACT
Brain lesions in the visual associative cortex are known to impair visual perception, i.e., the capacity to correctly perceive different aspects of the visual world, such as motion, color, or shapes. Visual perception can be influenced by non-invasive brain stimulation such as transcranial direct current stimulation (tDCS). In a recently developed technique called high definition (HD) tDCS, small HD-electrodes are used instead of the sponge electrodes in the conventional approach. This is believed to achieve high focality and precision over the target area. In this paper we tested the effects of cathodal and anodal HD-tDCS over the right V5 on motion and shape perception in a single blind, within-subject, sham controlled, cross-over trial. The purpose of the study was to prove the high focality of the stimulation only over the target area. Twenty one healthy volunteers received 20 min of 2 mA cathodal, anodal and sham stimulation over the right V5 and their performance on a visual test was recorded. The results showed significant improvement in motion perception in the left hemifield after cathodal HD-tDCS, but not in shape perception. Sham and anodal HD-tDCS did not affect performance. The specific effect of influencing performance of visual tasks by modulating the excitability of the neurons in the visual cortex might be explained by the complexity of perceptual information needed for the tasks. This provokes a "noisy" activation state of the encoding neuronal patterns. We speculate that in this case cathodal HD-tDCS may focus the correct perception by decreasing global excitation and thus diminishing the "noise" below threshold.

No MeSH data available.


Related in: MedlinePlus

Experimental design of the single blind within-subject, sham controlled randomized cross-over trial.
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Figure 1: Experimental design of the single blind within-subject, sham controlled randomized cross-over trial.

Mentions: The study was designed as a single blind, within-subject, sham controlled, randomized, cross-over trial. Prior to the study, all subjects gave written informed consent. Subjects performed a practice session of the visual tests, followed by the actual testing session. As a control task, subjects also performed an alertness task, preceded by a corresponding practice session (Zimmermann and Fimm, 2002). The stimulation (anodal, cathodal, or sham) was then administered. Right after the stimulation, the subjects then repeated the visual tests and the alertness task, this time without practice sessions. Performance during the stimulation was not measured. In this way, participants could make a break between the two sessions and an attention decrease due to tiredness was avoided. Finally, they were asked about potential adverse effects, such as headache, nausea, pain, or trouble concentrating (Villamar et al., 2013). Moreover, they were asked to state whether they believed to have received sham or real stimulation. The experimental design is depicted in Figure 1.


Cathodal HD-tDCS on the right V5 improves motion perception in humans.

Zito GA, Senti T, Cazzoli D, Müri RM, Mosimann UP, Nyffeler T, Nef T - Front Behav Neurosci (2015)

Experimental design of the single blind within-subject, sham controlled randomized cross-over trial.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585077&req=5

Figure 1: Experimental design of the single blind within-subject, sham controlled randomized cross-over trial.
Mentions: The study was designed as a single blind, within-subject, sham controlled, randomized, cross-over trial. Prior to the study, all subjects gave written informed consent. Subjects performed a practice session of the visual tests, followed by the actual testing session. As a control task, subjects also performed an alertness task, preceded by a corresponding practice session (Zimmermann and Fimm, 2002). The stimulation (anodal, cathodal, or sham) was then administered. Right after the stimulation, the subjects then repeated the visual tests and the alertness task, this time without practice sessions. Performance during the stimulation was not measured. In this way, participants could make a break between the two sessions and an attention decrease due to tiredness was avoided. Finally, they were asked about potential adverse effects, such as headache, nausea, pain, or trouble concentrating (Villamar et al., 2013). Moreover, they were asked to state whether they believed to have received sham or real stimulation. The experimental design is depicted in Figure 1.

Bottom Line: The results showed significant improvement in motion perception in the left hemifield after cathodal HD-tDCS, but not in shape perception.Sham and anodal HD-tDCS did not affect performance.The specific effect of influencing performance of visual tasks by modulating the excitability of the neurons in the visual cortex might be explained by the complexity of perceptual information needed for the tasks.

View Article: PubMed Central - PubMed

Affiliation: Gerontechnology and Rehabilitation Group, University of Bern Bern, Switzerland.

ABSTRACT
Brain lesions in the visual associative cortex are known to impair visual perception, i.e., the capacity to correctly perceive different aspects of the visual world, such as motion, color, or shapes. Visual perception can be influenced by non-invasive brain stimulation such as transcranial direct current stimulation (tDCS). In a recently developed technique called high definition (HD) tDCS, small HD-electrodes are used instead of the sponge electrodes in the conventional approach. This is believed to achieve high focality and precision over the target area. In this paper we tested the effects of cathodal and anodal HD-tDCS over the right V5 on motion and shape perception in a single blind, within-subject, sham controlled, cross-over trial. The purpose of the study was to prove the high focality of the stimulation only over the target area. Twenty one healthy volunteers received 20 min of 2 mA cathodal, anodal and sham stimulation over the right V5 and their performance on a visual test was recorded. The results showed significant improvement in motion perception in the left hemifield after cathodal HD-tDCS, but not in shape perception. Sham and anodal HD-tDCS did not affect performance. The specific effect of influencing performance of visual tasks by modulating the excitability of the neurons in the visual cortex might be explained by the complexity of perceptual information needed for the tasks. This provokes a "noisy" activation state of the encoding neuronal patterns. We speculate that in this case cathodal HD-tDCS may focus the correct perception by decreasing global excitation and thus diminishing the "noise" below threshold.

No MeSH data available.


Related in: MedlinePlus