Spatiotemporal Dynamics of High-Gamma Activities during a 3-Stimulus Visual Oddball Task
et al. (2013) Spatiotemporal Dynamics of High-Gamma Activities during a 3-Stimulus Visual
Oddball Task. PLoS ONE 8(3): e59969. doi:10.1371/journal.pone.0059969
Spatiotemporal Dynamics of High-Gamma Activities during a 3-Stimulus Visual Oddball Task
Yoritaka Akimoto 0
Akitake Kanno 0
Toshimune Kambara 0
Takayuki Nozawa 0
Motoaki Sugiura 0
Eiichi Okumura 0
Ryuta Kawashima 0
Lawrence M. Ward, University of British Columbia, Canada
0 1 Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University , Sendai , Japan , 2 Faculty of Environment and Information Studies, Keio University , Kanagawa , Japan , 3 Smart Ageing International Research Center, Institute of Development, Aging and Cancer, Tohoku University , Sendai , Japan , 4 International Research Institute of Disaster Science, Tohoku University , Sendai , Japan , 5 Department of Epileptology, Tohoku University Graduate School of Medicine , Sendai , Japan , 6 Division of Developmental Cognitive Neuroscience, Institute of Development, Aging and Cancer, Tohoku University , Sendai , Japan
Although many studies have investigated the neural basis of top-down and bottom-up attention, it still requires refinement in both temporal and spatial terms. We used magnetoencephalography to investigate the spatiotemporal dynamics of highgamma (52-100 Hz) activities during top-down and bottom-up visual attentional processes, aiming to extend the findings from functional magnetic resonance imaging and event-related potential studies. Fourteen participants performed a 3stimulus visual oddball task, in which both infrequent non-target and target stimuli were presented. We identified highgamma event-related synchronization in the left middle frontal gyrus, the left intraparietal sulcus, the left thalamus, and the visual areas in different time windows for the target and non-target conditions. We also found elevated imaginary coherence between the left intraparietal sulcus and the right middle frontal gyrus in the high-gamma band from 300 to 400 ms in the target condition, and between the left thalamus and the left middle frontal gyrus in theta band from 150 to 450 ms. In addition, the strength of high-gamma imaginary coherence between the left middle frontal gyrus and left intraparietal sulcus, between the left middle frontal gyrus and the right middle frontal gyrus, and the high-gamma power in the left thalamus predicted inter-subject variation in target detection response time. This source-level electrophysiological evidence enriches our understanding of bi-directional attention processes: stimulus-driven bottom-up attention orientation to a salient, but irrelevant stimulus; and top-down allocation of attentional resources to stimulus evaluation.
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Funding: This work was supported by a Grant-In-Aid for young scientists (B) (23700305) from the Japan Society for Promotion of Science (JSPS) (JSPS HP: http://
www.jsps.go.jp/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Attention is important for various cognitive functions, such as
selection of visual information and attentional resource allocation.
The oddball paradigm, wherein stimuli are presented with
different probabilities, has been frequently used to study the
mechanism of attention. The 3-stimulus oddball paradigm
includes two different infrequent stimuli, namely, the target and
the infrequent non-target in addition to one frequent stimulus. It
has been hypothesized that the processing of the target stimulus
entails top-down allocation of attentional resources for stimulus
evaluation [1,2], while the processing of the infrequent non-target
stimulus involves stimulus-driven bottom-up attentional
orientation to a salient but irrelevant stimulus [3,4]. Previous functional
magnetic resonance imaging (fMRI) studies revealed the
involvement of the occipital regions in the processing of infrequent
nontarget stimuli [4,5], and the involvement of the middle frontal
gyrus (MFG), intraparietal sulcus (IPS), and thalamus during target
detection [57]. These regions are involved in the cortical circuits
that guide bottom-up and top-down attention [8]. A previous
fMRI study also revealed that functional connectivity within
attention network is linked to behavioral performance, i.e.,
reaction time [9].
Although fMRI has excellent spatial resolution, it has limited
time resolution, due to the slow hemodynamic response. On the
other hand, electrophysiological measurements, such as
electroencephalogram (EEG) or magnetoencephalography (MEG)
provide very good temporal resolution. It is well known that
infrequent stimuli in the oddball paradigm elicit the P300
eventrelated potential (ERP), which contains at least two distinguishable
subcomponents, namely, P3a and P3b. P3b is elicited by
infrequent target stimuli, typically 300 to 600 ms (...truncated)