Ann Rehabil Med.  2012 Feb;36(1):1-7. 10.5535/arm.2012.36.1.1.

Effect of Stimulation Polarity of Transcranial Direct Current Stimulation on Non-dominant Hand Function

• Sohn MK
• Kim BO
• Song HT

• KMID: 2266774
• DOI: http://doi.org/10.5535/arm.2012.36.1.1

Abstract

OBJECTIVE
To evaluate motor excitability and hand function on the non-dominant side according to the polarity of transcranial direct current stimulation (tDCS) on the motor cortex in a healthy person. METHOD: tDCS was applied to the hand motor cortex for 15 minutes at an intensity of 1 mA in 28 healthy right-handed adults. Subjects were divided randomly into four groups: an anodal tDCS of the non-dominant hemisphere group, a cathodal tDCS of the non-dominant hemisphere group, an anodal tDCS of the dominant hemisphere group, and a sham group. We measured the motor evoked potential (MEP) in the abductor pollicis brevis and Jabsen-Taylor hand function test (JTT) in the non-dominant hand prior to and following tDCS. All study procedures were done under double-blind design.
RESULTS
There was a significant increase in the MEP amplitude and a significant improvement in the JTT in the non-dominant hand following anodal tDCS of the non-dominant hemisphere (p<0.05). But there was no change in JTT and a significant decrease in the MEP amplitude in the non-dominant hand following cathodal tDCS on the non-dominant hemisphere and anodal tDCS of the dominant hemisphere.
CONCLUSION
Non-dominant hand function is improved by increased excitability of the motor cortex. Although motor cortex excitability is decreased in a healthy person, non-dominant hand function is maintained. A homeostatic mechanism in the brain might therefore be involved in preserving this function. Further studies are warranted to examine brain functions to clarify this mechanism.

Keyword

tDCS; Transcranial direct current stimulation; Jabsen-Taylor hand function test; Cortical excitability

MeSH Terms

Adult
Brain
Evoked Potentials, Motor
Hand
Humans
Motor Cortex
Salicylamides
Salicylamides

Figure

• 

  Fig. 1 The MEP amplitude in the non-dominant abductor pollicis brevis before and after tDCS of the primary motor cortex showed a significant increase in the non-dominant anodal stimulation group (NDA), and a decrease in the non-dominant cathodal stimulation group (NDC) and the dominant anodal stimulation group (DA). Values are mean±standard deviation. Sham stimulation group(s).

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  Fig. 2 The total time of the Jabsen-Taylor test (JTT) in the non-dominant hand before and after tDCS of the primary motor cortex showed a significant decrease in the non-dominant anodal stimulation group (NDA). Values are mean±standard deviation. Sham stimulation group(s).

• 

  Fig. 3 There was a negative correlation between changes in percentile value of the MEP amplitude and Jabsen-Taylor test (JTT) in the non-dominant anodal stimulation group (NDA) (r=-0.843, p<0.05) and a positive correlation in the non-dominant cathodal stimulation group (NDC) (r=0.878, p<0.01).

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