Society for Neuroscience
Oct. 13-17, 2012
J. Rapela, K. Gramman*, M. Westerfield, J. Townsend, S. Makeig, Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA
*Berlin Technical University, Berlin, Germany
Brain oscillations in Switching vs. Focusing audio-visual attention
Selective attention contributes to perceptual efficiency by modulating cortical activity according to task demands. The majority of attentional research has focused on the effects of attention to a single modality, and less is known about the role of attention in multimodal sensory processing. Here we use electroencephalography (EEG) to study differences in oscillatory brain dynamics between quickly shifting attention among modalities and focusing attention on a single modality for extended periods of time. We also address interactions between attentional effects generated by the attention-shifting cues (anticipatory attention, Foxe et al. 1998) and those generated by subsequent stimuli (Fan et al. 2007).
In decompositions by independent components analysis (ICA, Delorme and Makeig 2004) of 33-channel EEG data from 19 subjects, we identified only two out of a total of 17 clusters of brain components that responded significantly differently to shifting versus focusing attention. A first cluster in the right middle occipital gyrus (Broadmann area 18) responded differently in the visual modality, and a second cluster in the left cingulate gyrus (Broadmann area 31) responded differently in the auditory modality. In addition, we observed that the attention-related activity (alpha desynchronization) evoked by stimuli following attention-shifting cues decayed progressively as the delay between the cues and the stimuli increased.
The existence of separate brain regions controlling shifts in attention to visual and auditory modalities suggests that the neural control of attention shifting is not supramodal but modality specific. The decay in attention related activity induced by stimuli presented at increasing delays following cue onsets explains intriguing observations in classical attentional experiments and opens new directions for the study of the physiological basis of multimodal attention.
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