Journal
CEREBRAL CORTEX
Volume 24, Issue 2, Pages 550-561Publisher
OXFORD UNIV PRESS INC
DOI: 10.1093/cercor/bhs343
Keywords
alpha; beamforming; brain oscillations; magnetoencephalography; spatial orienting
Categories
Funding
- Wellcome Trust [084067, 091928]
- UK' Economical and Social Research Council (ESRC)
- Medical Research Council (MRC)
- Spanish Ministry of Science and Innovation [2008-0168]
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Modulations of occipito-parietal -band (814 Hz) power that are opposite in direction (-enhancement vs. -suppression) and origin of generation (ipsilateral vs. contralateral to the locus of attention) are a robust correlate of anticipatory visuospatial attention. Yet, the neural generators of these -band modulations, their interdependence across homotopic areas, and their respective contribution to subsequent perception remain unclear. To shed light on these questions, we employed magnetoencephalography, while human volunteers performed a spatially cued detection task. Replicating previous findings, we found -power enhancement ipsilateral to the attended hemifield and contralateral -suppression over occipito-parietal sensors. Source localization (beamforming) analysis showed that -enhancement and suppression were generated in 2 distinct brain regions, located in the dorsal and ventral visual streams, respectively. Moreover, -enhancement and suppression showed different dynamics and contribution to perception. In contrast to the initial and transient dorsal -enhancement, -suppression in ventro-lateral occipital cortex was sustained and influenced subsequent target detection. This anticipatory biasing of ventro-lateral extrastriate -activity probably reflects increased receptivity in the brain region specialized in processing upcoming target features. Our results add to current models on the role of -oscillations in attention orienting by showing that -enhancement and suppression can be dissociated in time, space, and perceptual relevance.
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