Abstract
To-be-memorized information in working-memory could be protected against distracting influences by processes of functional inhibition or prioritization. Modulations of oscillations in the alpha to beta range in task-relevant sensory regions have been suggested to play an important role for both mechanisms. We adapted a Sternberg task variant to the auditory modality, with a strong or a weak distracting sound presented at a predictable time during the retention period. Using a time-generalized decoding approach, relatively decreased strength of memorized information was found prior to strong distractors, paralleled by decreased pre-distractor alpha/beta power in the left superior temporal gyrus (lSTG). Over the entire group, reduced beta power in lSTG was associated with relatively increased strength of memorized information. The extent of alpha power modulations within participants was negatively correlated with strength of memorized information. Overall, our results are compatible with a prioritization account, but point to nuanced differences between alpha and beta oscillations.
Highlights
Adaptive sensory processing entails the prioritization of task-relevant features with respect to competing information
Using magnetoencephalography (MEG), our study shows marked differences for an analogous task in the auditory system, with alpha desynchronization prior to the strong distractor in left auditory cortical regions putatively relevant for the representation of the verbal memory probe
Using multivariate pattern analysis (MVPA) we show that lower pre-distractor alpha power in left auditory cortex goes along with enhanced representation of the memory probe during the retention interval
Summary
Adaptive sensory processing entails the prioritization of task-relevant features with respect to competing information. (Haegens et al, 2009)) and auditory modality (e.g (Obleser et al, 2012)), putatively protecting the tobe-remembered information against interference While this load dependent top-down amplification of alpha is widely accepted, circumscribed decreases in alpha power (often labeled as desynchronization) have been deemed functionally important in the context of working memory tasks, reflecting an enhanced activation of performance-relevant neural ensembles A recent framework by Hanslmayr et al aiming at explaining the role of neural oscillations underlying episodic memory (Hanslmayr et al, 2016) explicitly links the extent of alpha desynchronization to the representational strength of the information content This is in line with a framework by van Ede (van Ede, 2018) who stresses the importance of circumscribed alpha decreases when item-specific information needs to be prioritized in the retention period of working memory tasks. In order to exert optimal control over perceptual processing, the brain exploits relevant cues such as temporal regularities (Rohenkohl and Nobre, 2011; van Ede et al, 2018) to regulate the excitatory-inhibitory balance in (ir-)relevant neural ensembles in an anticipatory manner
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