Ketamine increases fronto-posterior functional connectivity during meta-perceptual confidence ratings

Area of Science:

• Neuropsychopharmacology
• Cognitive Neuroscience
• Neuroimaging

Background:

• Glutamate is crucial for metacognition, but its role across different cognitive functions is not fully understood.
• Investigating the N-methyl-D-aspartate (NMDA) receptor system's impact on metacognition is essential for understanding its broader implications.

Purpose of the Study:

• To examine the effects of ketamine, an NMDA receptor antagonist, on metacognition within a perceptual decision-making task.
• To assess how ketamine influences both metacognitive performance and underlying neural activity using functional magnetic resonance imaging (fMRI).

Main Methods:

• A randomized, double-blind, placebo-controlled, and preregistered fMRI study.
• Participants performed a two-alternative forced-choice task with trial-by-trial metacognitive confidence ratings.
• A psychotomimetic dose of ketamine was administered to assess its impact on brain function and behavior.

Main Results:

• Ketamine significantly worsened metacognitive performance, specifically affecting confidence judgments.
• No significant effects of ketamine were found on perceptual accuracy, response times, or metacognitive bias.
• Exploratory analysis revealed altered functional connectivity patterns in brain regions associated with metacognition under ketamine.

Conclusions:

• Ketamine disrupts metacognitive processes, highlighting the role of the NMDA receptor system in metacognitive integrity.
• Findings suggest that ketamine may alter neural representations involved in metacognitive evaluation.
• This research contributes to understanding the neurochemical basis of metacognition and its disruption.