The effects of high-frequency transcranial random noise stimulation (hf-tRNS) on global motion processing: An equivalent noise approach

Ghin, Filippo and Pavan, Andrea and Contillo, Adriano and Mather, George (2018) The effects of high-frequency transcranial random noise stimulation (hf-tRNS) on global motion processing: An equivalent noise approach. Brain Stimulation . ISSN 1935-861X

Full content URL: https://www.sciencedirect.com/science/article/pii/...

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The effects of high-frequency transcranial random noise stimulation (hf-tRNS) on global motion processing: An equivalent noise approach

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Abstract

BACKGROUND:

High frequency transcranial random noise stimulation (hf-tRNS) facilitates performance in several perceptual and cognitive tasks, however, little is known about the underlying modulatory mechanisms.
OBJECTIVE:

In this study we compared the effects of hf-tRNS to those of anodal and cathodal tDCS in a global motion direction discrimination task. An equivalent noise (EN) paradigm was used to assess how hf-tRNS modulates the mechanisms underlying local and global motion processing.
METHOD:

Motion coherence threshold and slope of the psychometric function were estimated using an 8AFC task in which observers had to discriminate the motion direction of a random dot kinematogram presented either in the left or right visual hemi-field. During the task hf-tRNS, anodal and cathodal tDCS were delivered over the left hMT+. In a subsequent experiment we implemented an EN paradigm in order to investigate the effects of hf-tRNS on the mechanisms involved in visual motion integration (i.e., internal noise and sampling).
RESULTS:

hf-tRNS reduced the motion coherence threshold but did not affect the slope of the psychometric function, suggesting no modulation of stimulus discriminability. Anodal and cathodal tDCS did not produce any modulatory effects. EN analysis in the last experiment found that hf-tRNS modulates sampling but not internal noise, suggesting that hf-tRNS modulates the integration of local motion cues.
CONCLUSION:

hf-tRNS interacts with the output neurons tuned to directions near to the directional signal, incrementing the signal-to-noise ratio and the pooling of local motion cues and thus increasing the sensitivity for global moving stimuli.

Additional Information:The final published version of this article can be accessed online at https://www.sciencedirect.com/science/article/pii/S1935861X18302523
Keywords:Directional tuning, Global motion, Global sampling, High-frequency transcranial random noise stimulation, Internal noise
Subjects:C Biological Sciences > C850 Cognitive Psychology
B Subjects allied to Medicine > B140 Neuroscience
Divisions:College of Social Science > School of Psychology
ID Code:33276
Deposited On:22 Oct 2018 13:45

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