Stochastic resonance enhances the rate of evidence accumulation during combined brain stimulation and perceptual decision-making

• Published in: PLoS computational biology Vol. 14; no. 7; p. e1006301
• Main Authors: van der Groen, Onno, Tang, Matthew F, Wenderoth, Nicole, Mattingley, Jason B
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18-07-2018; Public Library of Science (PLoS)
• Subjects: Accumulation; Adolescent; Adult; Biology and Life Sciences; Brain; Brain stimulation; Computer Simulation; Cortex (somatosensory); Decision Making; Decisions; Diffusion rate; Drift; Drift rate; Eye; Female; Fovea; Health sciences; Humans; Laboratories; Male; Mathematical models; Medicine and Health Sciences; Models, Neurological; Motion Perception; Neurophysiology; Noise; Nonlinear systems; Psychological aspects; Random noise; Resonance; Retina; Signal quality; Social Sciences; Stimulation; Stochastic Processes; Stochastic resonance; Stochasticity; Visual cortex; Visual Cortex - physiology; Visual Perception - physiology; Visual stimuli; Visual thresholds; Young Adult; Queensland Australia; Switzerland; St Lucia
• ISSN: 1553-7358; 1553-734X; 1553-7358
• DOI: 10.1371/journal.pcbi.1006301

Perceptual decision-making relies on the gradual accumulation of noisy sensory evidence. It is often assumed that such decisions are degraded by adding noise to a stimulus, or to the neural systems involved in the decision making process itself. But it has been suggested that adding an optimal amount of noise can, under appropriate conditions, enhance the quality of subthreshold signals in nonlinear systems, a phenomenon known as stochastic resonance. Here we asked whether perceptual decisions made by human observers obey these stochastic resonance principles, by adding noise directly to the visual cortex using transcranial random noise stimulation (tRNS) while participants judged the direction of coherent motion in random-dot kinematograms presented at the fovea. We found that adding tRNS bilaterally to visual cortex enhanced decision-making when stimuli were just below perceptual threshold, but not when they were well below or above threshold. We modelled the data under a drift diffusion framework, and showed that bilateral tRNS selectively increased the drift rate parameter, which indexes the rate of evidence accumulation. Our study is the first to provide causal evidence that perceptual decision-making is susceptible to a stochastic resonance effect induced by tRNS, and to show that this effect arises from selective enhancement of the rate of evidence accumulation for sub-threshold sensory events.