Decoding working memory of stimulus contrast in early visual cortex.

Area of Science:

• Neuroscience
• Cognitive Science
• Visual Perception

Background:

• Early visual areas (V1-V3) primarily process elemental visual features like orientation and contrast.
• Emerging evidence suggests these areas also contribute to short-term visual stimulus retention in working memory.
• Previous studies decoded orientation from fMRI signals during memory recall.

Purpose of the Study:

• To investigate if working memory traces extend beyond orientation to other visual features like contrast.
• To determine if early visual cortex maintains consistent neural representations for perceived and remembered stimuli.
• To explore the influence of stimulus eccentricity on decoding visual features in working memory.

Main Methods:

• Functional magnetic resonance imaging (fMRI) in human participants.
• Multivariate pattern analysis (MVPA) to decode stimulus properties from brain activity.
• Classification of fMRI signals for perceived and remembered visual contrast.

Main Results:

• Visual contrast could be decoded from fMRI signals in early visual cortex for perceived stimuli, even when accounting for mean response changes.
• fMRI responses also allowed for decoding of visual contrast when it needed to be remembered.
• Decoding performance generalized between perceived and remembered stimuli, indicating consistent neural patterns.
• Stimulus decoding was influenced by stimulus eccentricity, providing constraints on interpretation.

Conclusions:

• Early visual cortex (V1-V3) supports working memory for visual features beyond orientation, including contrast.
• Neural representations for perceived and remembered stimuli are highly consistent in these early visual areas.
• Eccentricity-dependent biases influence the decoding of visual features, impacting our understanding of their neural correlates.