EP 69. Brain state dependent inhibitory and facilitatory effects following transcranial random noise stimulation in two motor tasks. Issue 9 (September 2016)

• Record Type: Journal Article
• Authors: Jooß, A.; Haberbosch, L.; Rönnefarth, M.; Fleischmann, R.; Scholz, M.; Brandt, S.; Schmidt, S.
• Is Part Of: Clinical neurophysiology. Volume 127:Issue 9(2016:Sep.)
• Page Start: e267
• Page End: e268
• Publication Date: 2016-09
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2016.05.120
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : Background: Transcranial random noise stimulation (tRNS) is a comparatively novel non-invasive neuromodulation technique. Its mechanism of action implies important benefits over more established methods such as transcranial direct current stimulation (tDCS). However, bi-directional effects related to the brain's activity state occur with tRNS despite its polarity independent properties. This intriguing potential of tRNS demands further structured investigation. Here, using one simple activating (finger tapping-task, FT) and one inhibitory task (go/no-go-task, GNG) confined to a functional domain (motor), we hypothesized that the underlying brain state would modulate the tRNS effect on corticospinal excitability (CSE). Methods: Twenty-nine healthy, right-handed individuals received tRNS at a stimulation intensity of 1mA with zero DC offset over the left primary motor cortex in a double-blind, sham-controlled study design. Participants were randomly assigned to two groups according to the motor task they were to perform during tRNS or sham stimulation. Thirteen participants performed a simple, activating FT-task while the remaining subjects performed an inhibitory motor task (GNG). CSE was evaluated before and after ten minutes of tRNS with navigated transcranial magnetic stimulation (nTMS). Results: In the tRNS condition, CSE after stimulation was significantly facilitated in the FT- group by a mean of +215 mV with standard error (SEM) ±129 mV, compared to an inhibition in the GNG- group of −142 mV and SEM ±87 mV ( p < 0.05). There was no significant difference between task types in the sham stimulation condition ( p = 0.967). Additionally, non-significant FT-fatigue differences after tRNS between the FT-group (6 SEM ± 0, 73%) and GNG-group (7 SEM ± 0, 86%) indicate that the stimulation effect on CSE was independent of task-specific fatigue ( p = 0, 4). Conclusions: Our results suggest that the neuromodulatory effects of tRNS are task- and brain state dependent, such that the underlying cortical activation state is enhanced. Control data show that this effect is independent of task induced fatigue. Utilizing brain states in tRNS protocols to modulate stimulation is a promising way to potentiate and induce neuroplastic aftereffects.