Opposite modulation of brain functional networks implicated at low vs. high demand of attention and working memory.
BACKGROUND
Functional magnetic resonance imaging (fMRI) studies indicate that the brain organizes its activity into multiple functional networks (FNs) during either resting condition or task-performance. However, the functions of these FNs are not fully understood yet.


RESULTS
To investigate the operation of these FNs, spatial independent component analysis (sICA) was used to extract FNs from fMRI data acquired from healthy participants performing a visual task with two levels of attention and working memory load. The task-related modulations of extracted FNs were assessed. A group of FNs showed increased activity at low-load conditions and reduced activity at high-load conditions. These FNs together involve the left lateral frontoparietal cortex, insula, and ventromedial prefrontal cortex. A second group of FNs showed increased activity at high-load conditions and reduced activity at low-load conditions. These FNs together involve the intraparietal sulcus, frontal eye field, lateral frontoparietal cortex, insula, and dorsal anterior cingulate, bilaterally. Though the two groups of FNs showed opposite task-related modulations, they overlapped extensively at both the lateral and medial frontoparietal cortex and insula. Such an overlap of FNs would not likely be revealed using standard general-linear-model-based analyses.


CONCLUSIONS
By assessing task-related modulations, this study differentiated the functional roles of overlapping FNs. Several FNs including the left frontoparietal network are implicated in task conditions of low attentional load, while another set of FNs including the dorsal attentional network is implicated in task conditions involving high attentional demands.
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States.
Jiansong
J
Xu
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States ; The Mind Research Network, Albuquerque, New Mexico, United States ; Department of ECE, The University of New Mexico, Albuquerque, New Mexico, United States.
Vince D
VD
Calhoun
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States ; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States ; Olin Neuropsychiatry Research Center, Institute of Living, Hartford, Connecticut, United States.
Godfrey D
GD
Pearlson
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States ; Child Study Center, Yale University School of Medicine, New Haven, Connecticut, United States ; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States.
Marc N
MN
Potenza
D000328:Adult; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008568:Memory / Q000502:physiology*; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000502:physiology*; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000502:physiology; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011859:Radiography; D013997:Time Factors; D055815:Young Adult