Neuronal signatures of a random-dot motion comparison task.

Area of Science:

• Cognitive Neuroscience
• Perceptual Decision Making
• Electrophysiology

Background:

• Perceptual decision making research utilizes distinct paradigms: vibrotactile frequency comparison (working memory) and random-dot motion (evidence accumulation).
• Previous studies show neural correlates like firing rates and beta oscillations in somatosensory tasks, and increased potentials in visual tasks, suggesting different mechanisms.

Purpose of the Study:

• To bridge the gap between somatosensory and visual decision-making paradigms by using a sequential visual comparison task.
• To investigate neural mechanisms underlying working memory and evidence accumulation in a unified experimental framework.

Main Methods:

• Human volunteers performed a sequential visual random-dot motion comparison task.
• Electroencephalography (EEG) was recorded to analyze brain activity.
• Analysis focused on prefrontal beta band power modulations and centro-parietal signal build-up.

Main Results:

• Prefrontal beta band power modulated with the coherence of the initial visual stimulus during a retention interval, indicating working memory involvement.
• Beta power in premotor areas correlated with participant choices ~700 ms prior to response.
• A build-up of centro-parietal signals occurred until response, varying with trial difficulty, consistent with evidence accumulation.

Conclusions:

• Neural modulations of beta power observed in tactile working memory tasks extend to the visual domain.
• The findings support evidence accumulation as a flexible decision-making mechanism applicable across different sensory modalities and task types.