Modulation of long-range neural synchrony reflects temporal limitations of visual attention in humans

doi:10.1073/pnas.0404944101

Modulation of long-range neural synchrony reflects temporal limitations of visual attention in humans

^*Department of Neurology, Heinrich-Heine University, 40225 Düsseldorf, Germany; ^†University of Wales, Bangor LL57 2DG, Wales; and ^‡Leiden University, 2300 RA, Leiden, The Netherlands

Communicated by Anne Treisman, Princeton University, Princeton, NJ, July 27, 2004 (received for review March 14, 2004)

Abstract

Because of attentional limitations, the human visual system can process for awareness and response only a fraction of the input received. Lesion and functional imaging studies have identified frontal, temporal, and parietal areas as playing a major role in the attentional control of visual processing, but very little is known about how these areas interact to form a dynamic attentional network. We hypothesized that the network communicates by means of neural phase synchronization, and we used magnetoencephalography to study transient long-range interarea phase coupling in a well studied attentionally taxing dual-target task (attentional blink). Our results reveal that communication within the fronto-parieto-temporal attentional network proceeds via transient long-range phase synchronization in the beta band. Changes in synchronization reflect changes in the attentional demands of the task and are directly related to behavioral performance. Thus, we show how attentional limitations arise from the way in which the subsystems of the attentional network interact.

Footnotes

↵ § To whom correspondence should be addressed at: Department of Neurology, MEG, Heinrich-Heine University, Moorenstrasse 5, 40225 Duesseldorf, Germany. E-mail: schnitza{at}uni-duesseldorf.de.
Abbreviations: AB, attentional blink; ROI, region of interest; SI, phase synchronization index; TFR, time-frequency representation.
↵ ¶ Although the synchronization analysis is necessarily more sensitive to adjacent regions of cortex as per the eight identified ROIs, the highest degree of synchronization as reported subsequently is found for highly separate cortical areas.
↵ ∥ For each trial and channel group, phases were randomly shifted, thereby destroying phase synchronization.
↵ ** Only connections that passed the significance tests described in Materials and Methods were classified.
↵ †† Negative values arise from the bandpass filter applied to the SI time course.
↵ ‡‡ The sensitivity profile of a sensor contains at each point in the brain the measurement value that a unit source at this point would generate in the sensor.