Decoding reveals the contents of visual working memory in early visual areas

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Visual working memory (VWM) is crucial for linking perception and cognition.
• Sustained activity in higher-order brain areas is thought to support VWM, but how specific features are maintained is unclear.
• Early visual areas typically show minimal sustained activity, posing a challenge for explaining precise feature recall.

Purpose of the Study:

• To investigate whether early visual areas retain specific visual feature information during VWM maintenance.
• To determine if fine-grained feature representations persist over extended delays.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Pattern classification techniques were applied to decode remembered visual features from activity patterns.
• Participants maintained one of two oriented gratings in VWM over a delay period.

Main Results:

• Activity patterns in early visual areas (V1-V4) accurately predicted the remembered orientation (>80% accuracy).
• These orientation-selective patterns were sustained throughout the delay period, even when overall activity returned to baseline.
• The neural representations were similar to those evoked by unattended stimuli.

Conclusions:

• Early visual areas actively retain specific visual feature information during VWM.
• Sustained, fine-tuned neural representations in sensory cortex support precise VWM recall.
• This challenges the notion that only higher-order areas maintain detailed VWM content.