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Distributed representations reading club presentation by Alexander Backus. Aim: Decode working memory content from human EEG recordings. Methods. Modified delayed match-to-sample (DMS) task. Methods. Mean EEG activity in visual cortex. Methods. Nonlinear signal analysis
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Distributed representations reading club presentation by Alexander Backus Aim: Decode working memory content from human EEG recordings
Methods Modified delayed match-to-sample (DMS) task
Methods Mean EEG activity in visual cortex
Methods • Nonlinear signal analysis • Assumption: State of the dynamical system (e.g. epoch of a given dipole) at any given moment may be represented by an embedding vector, where recurrent states are represented by similar embedding vectors • Bandpassfiltering (different gamma bands) • Construct time-delay embedding vector for each dipole • Detect recurrent states using autocorrelation integral • Construct binary vector that denotes recurrent states • Classifier training on 180/240 trials • Four-fold cross-validation • Stats: Bootstrapestimation(permutation testing); Bonferroni correction
Results Classifier performance in left pFCduring encoding 100-200 Hz 60-100 Hz 30-60 Hz
Results Classifier performance during WM maintenance
Results Cross-frequency analysis Theta-gamma phase-amplitude coupling
Discussion • Synchronous firing in gamma band in pFC during working memory maintenance is stimulus specific • Support for gamma feature-binding hypothesis • Potentially useful for brain-computer interfacing
Thanks for your attention Questions or remarks?