Mnemonic and attentional roles for states of attenuated alpha oscillations in perceptual working memory: a review

Abstract

Alpha oscillations are often reported to be amplified during working memory (WM) retention, serving to disengage sensory areas to protect internal representations from external interference. At the same time, contemporary views of WM postulate that sensory areas may often also be recruited for retention. I here review recent evidence that during such ‘perceptual’ WM, alpha oscillations in mnemonically relevant sensory areas are not amplified but attenuated instead. I will argue that such attenuated alpha states serve a mnemonic role and, further, that larger attenuation may support item‐specific attentional prioritisation within perceptual WM. In critically evaluating this role, I also consider (and argue against) four alternatives to a strictly mnemonic account of the available data that may also prove useful to consider in future research. Finally, I highlight key implications of these data for the study of WM and for our understanding of the functional roles of states of attenuated alpha oscillations in cognition.

Auditory cortical alpha desynchronization prioritizes the representation of memory items during a retention period

“…Overall our study supports the important role of circumscribed alpha decreases in prioritizing relevant information in working memory (van Ede, 2018).…”

“…While this load dependent top-down amplification of alpha is widely accepted, also 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 (e.g. (Noh et al, 2014;Sauseng et al, 2009); see (van Ede, 2018) for review). 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.…”

Interpreting neural decoding models using grouped model reliance

“…Taken together, results from the cluster-based permutation tests are in conflict with 335 previous studies reporting scaling of alpha amplitude with working memory on an 336 across subject level [21,22,24,50]. Instead, the present study identified high 337 inter-individual variability of alpha amplitude and topography.…”

“…Apart from the alpha-band, theta-band power modulations are commonly reported 358 in the study of working memory load [21,24,33] and are hypothesized to play a crucial 359 role in organizing sequential information [22,24]. In the present study, decoding models 360 for most subjects did not rely on theta, with the exception of subject #4.…”

“…Neuronal oscillations are hypothesized to be involved in 72working memory by generating a temporal structure for the brain [19,20]. Amplitude 73 modulation of neuronal oscillations, in particular in the alpha frequency bands (8-14Hz), 74 is a robust finding in psychophysiological research [21][22][23]. It is hypothesized that these 75 power modulations aid the functional brain architecture during retention, protect 76 against interference and thereby manifest in relevant behavioral outcomes, as measured 77 by accuracy and reaction time [24,25].…”