Dynamic regulation of interregional cortical communication by slow brain oscillations during working memory

Abstract

Transiently storing information and mentally manipulating it is known as working memory. These operations are implemented by a distributed, fronto-parietal cognitive control network in the brain. The neural mechanisms controlling interactions within this network are yet to be determined. Here, we show that during a working memory task the brain uses an oscillatory mechanism for regulating access to prefrontal cognitive resources, dynamically controlling interactions between prefrontal cortex and remote neocortical areas. Combining EEG with non-invasive brain stimulation we show that fast rhythmical brain activity at posterior sites are nested into prefrontal slow brain waves. Depending on cognitive demand this high frequency activity is nested into different phases of the slow wave enabling dynamic coupling or de-coupling of the fronto-parietal control network adjusted to cognitive effort. This mechanism constitutes a basic principle of coordinating higher cognitive functions in the human brain.

Oscillatory brain activity and maintenance of verbal and visual working memory: a systematic review

“…Proskovec et al (2018) in a MEG study localized theta in the left dorsolateral prefrontal cortex and reported an increase, but their figure 3 shows the opposite pattern: after a short transient increase, theta decreased below baseline level and maintained in this state until probe presentation. Contrary to the results by Proskovec, theta continuously increased during delay period in two EEG studies in exactly the same paradigm (Berger et al, 2019;Eschmann et al, 2018). The spatial WM task employed by these three studies was first published in EEG study by Griesmayr et al (2014) 1 , which also reported a theta increase.…”

High-level stimulus template modulates neuronal response at the earlier processing stages

“…We have compared the stimulus-related activity during the HA stimulus processing between two cases: the previous LA and the previous HA stimuli. We have observed the higher β -and θ -band power across the occipital and parietal sensors in the former case for t < 0.15 s. The increased parietal θ -band power evidences the increased processing demands resulting in mobilization of the cognitive resources, i.e., the top-down attentional control and the working memory (Tseng et al, 2018;Berger et al, 2019). The high occipital and parietal β -band power characterizes the tasks that involve endogenous top-down processes, including the ambiguous stimuli processing (Engel and Fries, 2010).…”

Neuronal adaptation in the course of the prolonged task improves visual stimuli processing

“…At the same time, the activation of the prefrontal cortex indicates that the task accomplishing requires additional cognitive resources. It is also confirmed by an increase of the task-related θ -band activity (Berger et al (2019)). The task-related occipital α-power is associated with selective attention during stimulus processing.…”

“…At the same time, the activation of the 336 prefrontal cortex indicates that the task accomplishing requires additional cognitive 337 resources. It is also confirmed by an increase of the task-related θ-band activity [31].…”