title: 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.
authors.affiliation: Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Sungkyunkwan University Suwon, South Korea ; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Science and Technology (SAIHST), Sungkyunkwan University Seoul, South Korea.
authors.forename: Gusang
authors.initials: G
authors.lastname: Kwon
authors.affiliation: Center for Biosignals, Korea Research Institute of Standards and Science Daejeon, South Korea ; Department of Medical Physics, University of Science and Technology Daejeon, South Korea.
authors.forename: Sanghyun
authors.initials: S
authors.lastname: Lim
authors.affiliation: Center for Biosignals, Korea Research Institute of Standards and Science Daejeon, South Korea.
authors.forename: Min-Young
authors.initials: MY
authors.lastname: Kim
authors.affiliation: Center for Biosignals, Korea Research Institute of Standards and Science Daejeon, South Korea.
authors.forename: Hyukchan
authors.initials: H
authors.lastname: Kwon
authors.affiliation: Center for Biosignals, Korea Research Institute of Standards and Science Daejeon, South Korea.
authors.forename: Yong-Ho
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Center for Biosignals, Korea Research Institute of Standards and Science Daejeon, South Korea ; Department of Medical Physics, University of Science and Technology Daejeon, South Korea.
authors.forename: Kiwoong
authors.initials: K
authors.lastname: Kim
authors.affiliation: School of Business, Sungkyunkwan University Seoul, South Korea.
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Lee
authors.affiliation: Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Sungkyunkwan University Suwon, South Korea ; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Science and Technology (SAIHST), Sungkyunkwan University Seoul, South Korea ; Department of Biomedical Engineering, Sungkyunkwan University Suwon, South Korea ; Department of Biological Science, Sungkyunkwan University Suwon, South Korea.
authors.forename: Minah
authors.initials: M
authors.lastname: Suh
keywords: MEG and EEG; alpha band desynchronization; dual-task; frontal midline theta; oculomotor task; word recall task; working memory capacity