Oscillatory brain state predicts variability in working memory.

Journal article

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.

Authors: Myers, N; Stokes, M; Walther, L; Nobre, A

• Publication status: Published
• Publisher: Society for Neuroscience
• Journal: Journal of neuroscience : the official journal of the Society for Neuroscience
• Volume: 34
• Issue: 23
• Pages: 7735-7743
• Publication date: 2014-06-01
• DOI: 10.1523/jneurosci.4741-13.2014
• EISSN: 1529-2401
• ISSN: 0270-6474
• Language: English
• Keywords: Female; Healthy Volunteers; Statistics as Topic; Memory, Short-Term; Humans; Alpha Rhythm; Male; Young Adult; Electroencephalography; Parietal Lobe; Visual Perception; Brain Mapping; Predictive Value of Tests; Photic Stimulation; Adult