Evidence accumulation detected in BOLD signal using slow perceptual decision making

Area of Science:

• Neuroscience
• Cognitive Science
• Neuroimaging

Background:

• Observing evidence accumulation in the Blood-Oxygen-Level-Dependent (BOLD) signal during perceptual decision-making is challenging due to the slow hemodynamic response.
• Perceptual decisions are typically rapid, making it difficult to capture the neural processes of accumulating evidence.

Purpose of the Study:

• To investigate and observe evidence accumulation in the BOLD signal during perceptual decision-making.
• To identify brain regions specifically involved in the evidence accumulation process.

Main Methods:

• Slowed decision-making by penalizing incorrect responses, guided by drift-diffusion model predictions.
• Distinguished BOLD activity for stimulus detection (boxcar model) from integration (ramp model) by minimizing GLM regressor collinearity.
• Utilized a control condition without evidence accumulation to isolate neural processes.

Main Results:

• Found no evidence for previously proposed parietal cortex regions driving perceptual decision-making.
• Identified novel brain regions as candidates for involvement in evidence accumulation.
• The new method offers more sensitive and selective observation of evidence accumulation processes.

Conclusions:

• The study successfully slowed decision-making while preserving perceptual information, enabling clearer observation of evidence accumulation.
• This approach provides a more effective method for studying the neural basis of perceptual decision-making compared to prior techniques.