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Distributed and drifting signals for working memory load in human cortex
Kirsten C S Adam1, Edward Awh2,3, John T Serences4,5
1Department of Psychological Sciences, Rice University, Houston TX.
Biorxiv : the Preprint Server for Biology
|September 26, 2025
Summary
Neural constraints on working memory (WM) load are distributed across the cortex, not localized to the intraparietal sulcus. Brain activity patterns refine over time for efficient information storage.
Area of Science:
- Cognitive Neuroscience
- Neuroimaging
Background:
- Working memory (WM) load impacts behavior, with debate on whether neural constraints are localized or distributed.
- The intraparietal sulcus is a candidate region for localized WM load signals.
Purpose of the Study:
- To investigate the neural basis of working memory load.
- To determine if working memory load is encoded in a localized or distributed manner across the brain.
Main Methods:
- Functional magnetic resonance imaging (fMRI) in 12 human participants.
- Visual working memory task with varying memory loads (0-4 items).
- Analysis of univariate and multivariate brain activity patterns.
Main Results:
- Replicated localized load-dependent activity in parietal cortex.
- Observed distributed univariate activity changes across the visual hierarchy.
- Multivariate patterns encoded WM load irrespective of univariate effects, challenging localized theories.
- Detected representational drift in activity patterns over time.
Conclusions:
- Working memory load is encoded by distributed neural patterns, not restricted to the parietal cortex.
- Neural representations of memory load may be continually refined for efficiency.
