Temporally distinct oscillatory codes of retention and manipulation of verbal working memory

Abstract

Most psychophysiological studies of working memory (WM) target only the short-term memory construct, whereas short-term memory is only a part of the WM responsible for the storage of sensory information. Here, we aimed to further investigate oscillatory brain mechanisms supporting the executive components of WM-the part responsible for the manipulation of information.We conducted an exploratory reanalysis of a previously published EEG dataset where 156 participants (82 females) performed tasks requiring either simple retention or retention and manipulation of verbal information in WM. A relatively long delay period (>6 s) was employed to investigate the temporal trajectory of the oscillatory brain activity. Compared with baseline, theta activity was significantly enhanced during encoding and the delay period. Alpha-band power decreased during encoding and switched to an increase in the first part of the delay before returning to the baseline in the second part; beta-band power remained below baseline during encoding and the delay. The difference between the manipulation and retention tasks in spectral power had diverse temporal trajectories in different frequency bands. The difference maintained over encoding and the first part of the delay in theta, during the first part of the delay in beta, and during the whole delay period in alpha. Our results suggest that task-related modulations in theta power co-vary with the demands on the executive control network; beta suppression during mental manipulation can be related to the activation of motor networks; and alpha is likely to reflect the activation of language areas simultaneously with sensory input blockade.

Parietal Alpha Oscillations: Cognitive Load and Mental Toughness

“…We observed classic oscillatory correlates of the Sternberg task condition in the alpha band: parietal ERD related to encoding, parietal-occipital ERS related to retention, and parietal ERD related to responding to a probe. These results concur with findings in magnetoencephalography (MEG) and EEG studies [ 8 , 43 , 47 , 49 , 50 ]. ERD related to encoding and retrieval may be interpreted as cortical activation [ 10 ] and visual attention enhancement required during information encoding and/or information retrieval in working memory [ 10 , 44 , 81 , 82 , 83 ].…”

“…Statistical analysis was conducted using electrodes selected a priori and confirmed by the peak ERD/ERS of the alpha rhythm related to the baseline on the topography figures ( Figure 2 ). A priori, alpha rhythm depression was expected on the parietal lateral electrodes (P3, P4), whereas alpha rhythm activation was expected to be observed on the parietal-occipital lateral electrodes (PO7, PO8), in accordance with previous EEG studies using the Sternberg task [ 47 , 50 ].…”

“…It requires participants to encode a set of items presented on the screen, retain them for a short period of time, and in a subsequent screen identify whether a target item was a member of the original set. Neuroimaging studies show that these three stages of performance are expressed in the modulation of the alpha rhythm [ 8 , 43 , 49 , 50 ]. Posterior ERD is observed during the stage of encoding information (ERD during encoding), posterior ERS is observed during the stage of information retention (ERS during retention), and posterior ERD is observed again before and during the response phase (ERD related to response preparation and execution).…”

“…Critically, no study has revealed in the same sample both effects when examining Sternberg task performance. Specifically, studies that examined both these effects did not reveal significant relations between encoding-related ERD and task difficulty [ 8 , 46 , 47 , 49 , 50 ]. Further, most studies do not calculate the individual alpha frequency for their analyses, while alpha frequency peak is known to show large individual differences and, thus, analysis of fixed frequency ranges may not be useful for studying alpha power modulation effects [ 9 ].…”

Альфа- И Тета- Ритмы Как Маркеры Когнитивного Усилия

“…Meanwhile, like other cognitive tasks, the Sternberg task requires the activation of many processes, such as stimulus encoding, stimulus retention in working memory, stimulus retrieval from working memory (Sternberg, 1996). Time-frequency analysis of oscillations associated with the execution of the Sternberg problem makes it possible to separate these processes (Wianda & Ross, 2019;Proskovec et al, 2019;Heinrichs-Graham & Wilson, 2015;Pavlov & Kotchoubey, 2021) and examine their relationship to task difficulty and motivation separately. Therefore, the study of task-related oscillations may allow one to relate various top-down cognitive processes to theories of effort, and thus develop an understanding of the cognitive mechanism of effort.…”