Slow Wave Activity Related to Working Memory Maintenance in the N-Back Task

Abstract

Abstract. Working memory supports our ability to maintain goal-relevant information that guides cognition in the face of distraction or competing tasks. The N-back task has been widely used in cognitive neuroscience to examine the functional neuroanatomy of working memory. Fewer studies have capitalized on the temporal resolution of event-related brain potentials (ERPs) to examine the time course of neural activity in the N-back task. The primary goal of the current study was to characterize slow wave activity observed in the response-to-stimulus interval in the N-back task that may be related to maintenance of information between trials in the task. In three experiments, we examined the effects of N-back load, interference, and response accuracy on the amplitude of the P3b following stimulus onset and slow wave activity elicited in the response-to-stimulus interval. Consistent with previous research, the amplitude of the P3b decreased as N-back load increased. Slow wave activity over the frontal and posterior regions of the scalp was sensitive to N-back load and was insensitive to interference or response accuracy. Together these findings lead to the suggestion that slow wave activity observed in the response-to-stimulus interval is related to the maintenance of information between trials in the 1-back task.

Working memory updating training modulates a cascade of event-related potentials depending on task load

“…The role of maintenance in neuronal mechanisms of WM training: Our study tested the hypothesis that WM training would lead to more effective maintenance of the to-beremembered stimuli, as reflected by changes in slow waves occurring during active maintenance of WM contents (Bailey et al 2016, Vilà-Balló et al 2018. In accordance to our expectations, NSW was indeed affected by training.…”

“…In humans, slow negative components (NSW) persisting throughout the retention interval in WM tasks predict the number of objects to be maintained in memory (Fukuda et al 2010, Luria et al 2016. A slow wave related to active maintenance of WM contents between n-back trials has been reported in a few prior studies (Bailey et al 2016, Vilà-Balló et al 2018. There is evidence that also the amplitude of the contingent negative variation (CNV, Walter et al, 1964) during the retention interval is smaller when the memory load is higher (Ford et al 1979;Roth et al 1975;Roth et al 1978), but this response can be distinguished from the other slow waves based on its scalp distribution (e.g., McEvoy et al 1998).…”

“…Other WM component functions associated with updating include selection of incoming information, inhibition of the irrelevant information, and continuous monitoring of performance. Specific component functions required in updating are thought to vary depending on the task demands: when the executive demands are low, there are more resources available for the active maintenance of relevant information, and vice versa (Ecker et al 2010, Ecker et al 2013, Bailey et al 2016, Botto et al 2014 Running head: Updating training modulates ERPs Vilà-Balló et al 2018). Indeed, a few studies specifically focusing on WM maintenance have reported enhanced event-related potential (ERP) responses in the easy condition in which the participant should be able to keep the previous stimulus actively in mind, as compared with the more difficult condition in which constant maintenance is getting difficult because of the intervening stimuli (see Bailey et al 2016, Vilà-Balló et al 2018.…”

“…Specific component functions required in updating are thought to vary depending on the task demands: when the executive demands are low, there are more resources available for the active maintenance of relevant information, and vice versa (Ecker et al 2010, Ecker et al 2013, Bailey et al 2016, Botto et al 2014 Running head: Updating training modulates ERPs Vilà-Balló et al 2018). Indeed, a few studies specifically focusing on WM maintenance have reported enhanced event-related potential (ERP) responses in the easy condition in which the participant should be able to keep the previous stimulus actively in mind, as compared with the more difficult condition in which constant maintenance is getting difficult because of the intervening stimuli (see Bailey et al 2016, Vilà-Balló et al 2018. WM training studies conducted with fMRI have provided evidence that decreased brain activity is mostly observed in brain areas involved in earlier processing stages, while increased brain activity is observed in brain areas such as the prefrontal cortex that are involved in higher-level functions (Salmi et al 2018).…”

“…This hypothesis raises from nonhuman primate studies demonstrating that WM training results in an increase in the number of activated dorsal and ventral prefrontal neurons during maintenance of information in WM (Qi et al 2011). Our training task was a dual n-back task, because n-back tasks are amongst the most widely used WM tasks and because the slow wave responses related to maintenance has been identified with this paradigm (Bailey et al 2016, Vilà-Balló et al 2018. In an n-back task, the participant is to decide whether the current stimulus matches the one n steps back in the stimulus sequence.…”