Sustained effects of anodal tDCS over the dominant motor cortex on response preparation processes.
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1
University of Newcastle, School of Psychology, Australia
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2
University of Newcastle, School of Health Sciences, Australia
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3
University of Newcastle, School of Medicine and Public Health, Australia
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4
University of Newcastle, Centre for Translational Neuroscience and Mental Health Research, Australia
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5
University of Sydney, Brain & Mind Research Institute, Australia
Anodal transcranial direct current stimulation (tDCS) over the primary motor cortex increases motor excitability in healthy young adults, suggesting a potential clinical application to enhance motor rehabilitation post-stroke. However, the effects of tDCS on motor processes in healthy ageing have yet to be defined. We applied anodal tDCS over the dominant primary motor cortex to examine effects on response preparation processes in healthy older participants. Right-handed older adults received anodal tDCS vs. sham stimulation over the left (dominant) motor cortex in two counterbalanced sessions (3-wk delay). Response preparation was assessed using a cued go/nogo task with directional cues reliably indicating the response hand (cue-target interval 1500ms). Irrespective of stimulation order, anodal tDCS slowed response time on go trials compared to sham stimulation. The effect of stimulation on contingent negative variation (CNV) amplitude varied as a function of stimulation order. Participants who received the sham condition first showed reduced CNV amplitude in the active tDCS condition. The effect was greater for preparation of a response with the stimulated (dominant) hand, suggestive of less efficient response preparation in the stimulated cortex. Participants who received active tDCS first showed an identical effect on CNV amplitude under active tDCS. However, unexpectedly, this group also showed reduced CNV amplitude during the sham stimulation session that was run 3 weeks later. This suggests that learning the task under anodal tDCS may have disrupted the acquisition of an efficient response preparation strategy and that the less efficient strategy was maintained at re-test under sham stimulation.
Keywords:
transcranial direct current stimulation (tDCS),
Motor Cortex,
motor preparation,
Contingent Negative Variation,
older adults
Conference:
ACNS-2012 Australasian Cognitive Neuroscience Conference, Brisbane, Australia, 29 Nov - 2 Dec, 2012.
Presentation Type:
Oral Presentation
Topic:
Motor
Citation:
Conley
A,
Marquez
J,
Parsons
M,
Fulham
RW,
Lagopoulos
J and
Karayanidis
F
(2012). Sustained effects of anodal tDCS over the dominant motor cortex on response preparation processes..
Conference Abstract:
ACNS-2012 Australasian Cognitive Neuroscience Conference.
doi: 10.3389/conf.fnhum.2012.208.00027
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Received:
25 Oct 2012;
Published Online:
07 Nov 2012.
*
Correspondence:
Prof. Frini Karayanidis, University of Newcastle, School of Psychology, Newcastle, NSW 2308, Australia, frini.karayanidis@newcastle.edu.au