Individual differences in oscillatory brain activity in response to varying attentional demands during a word recall and oculomotor dual task

Abstract

Every day, we face situations that involve multi-tasking. How our brain utilizes cortical resources during multi-tasking is one of many interesting research topics. In this study, we tested whether a dual-task can be differentiated in the neural and behavioral responses of healthy subjects with varying degree of working memory capacity (WMC). We combined word recall and oculomotor tasks because they incorporate common neural networks including the fronto-parietal (FP) network. Three different types of oculomotor tasks (eye fixation, Fix-EM; predictive and random smooth pursuit eye movement, P-SPEM and R-SPEM) were combined with two memory load levels (low-load: five words, high-load: 10 words) for a word recall task. Each of those dual-task combinations was supposed to create varying cognitive loads on the FP network. We hypothesize that each dual-task requires different cognitive strategies for allocating the brain’s limited cortical resources and affects brain oscillation of the FP network. In addition, we hypothesized that groups with different WMC will show differential neural and behavioral responses. We measured oscillatory brain activity with simultaneous MEG and EEG recordings and behavioral performance by word recall. Prominent frontal midline (FM) theta (4–6 Hz) synchronization emerged in the EEG of the high-WMC group experiencing R-SPEM with high-load conditions during the early phase of the word maintenance period. Conversely, significant parietal upper alpha (10–12 Hz) desynchronization was observed in the EEG and MEG of the low-WMC group experiencing P-SPEM under high-load conditions during the same period. Different brain oscillatory patterns seem to depend on each individual’s WMC and varying attentional demands from different dual-task combinations. These findings suggest that specific brain oscillations may reflect different strategies for allocating cortical resources during combined word recall and oculomotor dual-tasks.

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

“…In addition to the above mentioned study of Harmony et al (1996), in one study the step-wise increase of theta activity was observed only in high performance participants (Pavlov and Kotchoubey, 2017). No observable and/or statistically significant step-wise increase was found in three studies (Kwon et al, 2015;Meltzer et al, 2007;Schack and Klimesch, 2002). As we can see, EEG verbal WM research strongly supports the hypothesis of involvement of theta oscillations in WM maintenance processes.…”

“…A change in alpha activity as a function of increasing load (step-wise change) was observed in 15 of them. In two cases no stepwise load-dependent alpha change in any direction was observed (Harmony et al, 1996;Kwon et al, 2015). A saturation effect was observed in two studies (Bashivan et al, 2014;Xie et al, 2016, see below).…”

“…None of the six studies with alpha decrease separated alpha into subbands. In one study the time-frequency maps allowed to track alpha in the subbands but no visually observable difference between them was noticeable (Kwon et al, 2015). Then we inspected all studies where time-frequency maps allowed us to observe changes in both alpha subbands.…”

Cognitive-motor dual-task interference: A systematic review of neural correlates

“…all articles measured the behavioral and neural activity changes. (Gruber 2001;Matthews, Garry et al 2006;Just, Keller et al 2008;Matthews, Martin et al 2009;Serrien 2009;Gazes, Rakitin et al 2010;Remy, Wenderoth et al 2010;Holtzer, Mahoney et al 2011;Van Impe, Coxon et al 2011;Johnson and Shinohara 2012;Doi, Makizako et al 2013;Johannsen, Li et al 2013;Mandrick, Derosiere et al 2013;Ohsugi, Ohgi et al 2013;Wu, Liu et al 2013;Beurskens, Helmich et al 2014;Blumen, Holtzer et al 2014;De Sanctis, Butler et al 2014;Meester, Al-Yahya et al 2014;Mirelman, Maidan et al 2014;Nijboer, Borst et al 2014;Kwon, Lim et al 2015;Malcolm, Foxe et al 2015).…”

“…Three studies used EEG (Matthews, Garry et al 2006;Matthews, Martin et al 2009;Serrien 2009), one used cortico-muscolar coherence measures (CMC MEG-EEG) (Johnson and Shinohara 2012), one used the simultaneous recording of EEG and MEG (Kwon, Lim et al 2015) and two used the mobile brain/body imaging technique (MOBI) (De Sanctis, Butler et al 2014; Malcolm, Foxe et al 2015).…”