The Neural Codes Underlying Internally Generated Representations in Visual Working Memory.

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Visual Perception

Background:

• Humans generate rich subjective experiences independent of external sensory input.
• Understanding the neural basis of internally generated information in visual working memory is crucial.

Purpose of the Study:

• To investigate the neural representation of purely internally generated stimulus-like information during visual working memory.
• To explore how the brain maintains internally generated versus externally influenced information.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to scan participants.
• Multivariate inverted encoding models reconstructed neural representations of orientation.
• Participants performed delayed recall tasks with varying contrast levels, including 0% contrast.

Main Results:

• Orientation information was successfully reconstructed from early visual cortex activity, even without external stimuli (0% contrast).
• This suggests a purely internally generated neural code exists in the early visual cortex.
• Internal and external information representations differed in early visual cortex and intraparietal sulcus.

Conclusions:

• The early visual cortex supports the generation and maintenance of purely internal representations.
• Distinct neural mechanisms may underlie the maintenance of internally generated versus externally driven information in working memory.
• Findings offer insights into how the brain integrates internal and external information streams.