Journal
JOURNAL OF NEUROSCIENCE
Volume 34, Issue 23, Pages 7735-7743Publisher
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.4741-13.2014
Keywords
alpha oscillations; cognitive variability; cortical excitability; precision; working memory
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Funding
- Wellcome Trust
- Medical Research Council
- National Institute for Health Research Oxford Biomedical Research Centre Programme at the Oxford University Hospitals Trust, Oxford University
- Medical Research Council [MR/J009024/1] Funding Source: researchfish
- MRC [MR/J009024/1] Funding Source: UKRI
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Our capacity to remember and manipulate objects in working memory (WM) is severely limited. However, this capacity limitation is unlikely to be fixed because behavioral models indicate variability from trial to trial. We investigated whether fluctuations in neural excitability at stimulus encoding, as indexed by low-frequency oscillations (in the alpha band, 8-14 Hz), contribute to this variability. Specifically, we hypothesized that the spontaneous state of alpha band activity would correlate with trial-by-trial fluctuations in visual WM. Electroencephalography recorded from human observers during a visual WM task revealed that the prestimulus desynchronization of alpha oscillations predicts the accuracy of memory recall on a trial-by-trial basis. A model-based analysis indicated that this effect arises from a modulation in the precision of memorized items, but not the likelihood of remembering them (the recall rate). The phase of posterior alpha oscillations preceding the memorized item also predicted memory accuracy. Based on correlations between prestimulus alpha levels and stimulus-related visual evoked responses, we speculate that the prestimulus state of the visual system prefigures a cascade of state-dependent processes, ultimately affecting WM-guided behavior. Overall, our results indicate that spontaneous changes in cortical excitability can have profound consequences for higher visual cognition.
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