Spectrotemporal dynamics of the EEG during working memory encoding and maintenance predicts individual behavioral capacity

Abstract

We investigated the effect of memory load on encoding and maintenance of information in working memory. Electroencephalography (EEG) signals were recorded while participants performed a modified Sternberg visual memory task. Independent component analysis (ICA) was used to factorise the EEG signals into distinct temporal activations to perform spectrotemporal analysis and localisation of source activities. We found 'encoding' and 'maintenance' operations were correlated with negative and positive changes in α-band power, respectively. Transient activities were observed during encoding of information in the bilateral cuneus, precuneus, inferior parietal gyrus and fusiform gyrus, and a sustained activity in the inferior frontal gyrus. Strong correlations were also observed between changes in α-power and behavioral performance during both encoding and maintenance. Furthermore, it was also found that individuals with higher working memory capacity experienced stronger neural oscillatory responses during the encoding of visual objects into working memory. Our results suggest an interplay between two distinct neural pathways and different spatiotemporal operations during the encoding and maintenance of information which predict individual differences in working memory capacity observed at the behavioral level.

Identifying neural correlates of visual consciousness with ALE meta-analyses

“…The disinhibitory effect of the basal ganglia on thalamocortical loops has been discussed as neural underpinning of the selective gating mechanism involved in the updating of working memory (Frank, Loughry, & O'Reilly, 2001;Rotshtein et al, 2011). The precuneus has been related to the updating of working memory (Bashivan et al, 2014;, while activation in the middle frontal gyrus/precentral gyurs has been shown to be mainly involved in spatial attention shifts towards visual stimuli (Kim et al, 2012;Nobre et al, 2004). The inferior frontal gyrus, superior frontal gyrus, inferior parietal lobule, and intraparietal sulcus have each been related to inhibitory control, working memory, and the updating of working memory in EEG, fMRI, patient, and ALE meta-analysis studies (e.g., Bashivan et al, 2014;Derrfuss et al, 2005;Laird et al, 2005b;Rotshtein et al, 2011;Rottschy et al, 2012;Voytek and Knight, 2010).…”

“…The precuneus has been related to the updating of working memory (Bashivan et al, 2014;, while activation in the middle frontal gyrus/precentral gyurs has been shown to be mainly involved in spatial attention shifts towards visual stimuli (Kim et al, 2012;Nobre et al, 2004). The inferior frontal gyrus, superior frontal gyrus, inferior parietal lobule, and intraparietal sulcus have each been related to inhibitory control, working memory, and the updating of working memory in EEG, fMRI, patient, and ALE meta-analysis studies (e.g., Bashivan et al, 2014;Derrfuss et al, 2005;Laird et al, 2005b;Rotshtein et al, 2011;Rottschy et al, 2012;Voytek and Knight, 2010). The superior parietal lobule has been shown to be involved in attentional shifts towards external stimuli (Kim et al, 2012;Nobre et al, 2004) as well as in inhibitory control and updating processes within working memory in an ALE meta-analysis on executive functions within working memory .…”

“…, the basal ganglia in selective gating processes necessary for updating working memory (e.g.,Frank, Loughry, & O'Reilly, 2001), and the fronto-parietal regions mainly in top-down attentional and/or selective inhibitory gating processes necessary for updating a visual representation in working memory(Bashivan et al, 2014; Derrfuss et al., 2005; Kim et al, 2012;Rottschy et al, 2012).4.5 Possible differences in the operationalization of NCC in different standard paradigms…”

“…The predominance of the right hemisphere in our results of the exploratory meta-analysis on the bistable perception paradigm is in line with effective connectivity studies showing that perceptual reversals in the bistable perception paradigm are induced by right-sided interactions of fronto-parietal areas with higher-level extrastriate areas(Megumi et al, 2015;Vernet et al, 2015;Weilnhammer et al, 2013). Given that the fronto-parietal regions resulting from our meta-analysis on the bistable perception paradigm have been shown to be involved in topdown selective attention, inhibitory control, and updating working memory (e.g.,Bashivan et al, 2014; Derrfuss et al, 2005; Kim et al, 2012;Rottschy et al, 2012; see section 4.4), the paradigm might primarily tap into top-down attentional modulation and the post-sensory gating mechanism involved in updating the content of the global workspace (e.g.,Kiefer et al, 2011). The results of our exploratory paradigm-specific meta-analyses thus suggest that, although in all standard paradigms for NCC visual consciousness is most probably measured via an interplay between stimulus-driven bottom-up processes, attentional top-down modulation, and a post-sensory gating mechanism, the respective weighting of these three processes might slightly differ between paradigms.…”

Memory load effect in auditory–verbal short-term memory task: EEG fractal and spectral analysis

“…While there is some methodological variability across studies, previous studies generally agree that five to seven items can be adequately stored and manipulated in STM (Bashivan et al 2014). We have chosen to use three, five, and seven words in order to explore three memory load levels.…”