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

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.

Alpha/beta power decreases during episodic memory formation predict the magnitude of alpha/beta power decreases during subsequent retrieval

“…However, our findings cannot be explained under this interpretation. While we were able to observe the reinstatement of alpha/beta power during retrieval, we were unable to decode stimulus identity within topographic patterns of alpha/beta power (matching earlier reports: Griffiths, Mayhew, et al, 2019;Ng, Logothetis, & Kayser, 2013;Weisz et al, 2020). This disparity is emphasised when one considers that the reinstatement of alpha/beta power during retrieval could be detected at single channels and frequencies using traditional univariate approaches, while links between stimulus identity and alpha/beta power were not forthcoming despite using more advanced multivariate approaches.…”

“…To this end, linear discriminant analysis (LDA) was used to decode stimulus identity during the presentation of the object (where LDA was used to discriminate animate vs. inanimate objects), feature (polka-dot vs. chequered), and scene (indoor vs. outdoor). When running LDA on broadband amplitude, the subcategories of all three stimulus types could be distinguished to a significantly greater these results suggest that while stimulus category can be decoded based on the recorded signal, alpha/beta power is not the driver of this result (replicating earlier reports; Griffiths, Mayhew, et al, 2019;Ng et al, 2013;Weisz et al, 2020). In other words, topographic patterns of alpha/beta power do not carry stimulus-specific information.…”

“…For example, a simultaneous EEG-fMRI study demonstrated that the magnitude of alpha/beta power decreases directly correlated with the amount of stimulus-specific information represented within the BOLD signal during both perception and episodic memory retrieval (Griffiths, Mayhew, et al, 2019). Notably, these alpha/beta power decreases did not represent stimulus-specific information, but rather provided the conditions which benefit information representation (for complementary evidence, see Weisz et al, 2020). One could therefore hypothesise that reductions in alpha/beta power serve to reduce noise rather than boost signal.…”

Distinct neural representations of content and ordinal structure in auditory sequence memory

“…Different from visual studies, only a few studies have assessed the neural correlates of auditory WM (Albouy et al, 2017;Kumar et al, 2016;Luo et al, 2013;Weisz et al, 2020;Wolff et al, 2020). Here, by combining RSA-based decoding and impulse-response approach, we demonstrate that a neutral white-noise auditory impulse could successfully reactivate the tone frequency information 'silently' held in auditory WM.…”

Sleep loss disrupts the neural signature of successful learning

“…A significant No significant differences were observed in the preregistered theta (4-8 Hz) or gamma (40-60 Hz) bands for subsequently remembered > forgotten adjective image pairings, sleep > sleep deprivation or the interaction between these contrasts (all p >.142). Given the previously reported links between alpha (8-12 Hz) desynchronization and successful learning 2021;Weisz et al, 2020), we also explored activity in this frequency band (same contrasts as above), but no significant effects were observed (all p >.396).…”