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Now you'll feel it, now you won't: EEG rhythms predict the effectiveness of perceptual masking

 
: Schubert, R.; Haufe, S.; Blankenburg, F.; Villringer, A.; Curio, G.

:

Journal of Cognitive Neuroscience 21 (2009), Nr.12, S.2407-2419
ISSN: 0898-929X
ISSN: 1096-8857
ISSN: 1530-8898
Englisch
Zeitschriftenaufsatz
Fraunhofer FIRST ()

Abstract
Do ongoing brain states determine conscious perception of an upcoming stimulus? Using the high temporal resolution of EEG, we investigated the relationship between prestimulus neuronal oscillations and the perceptibility of two competing somatosensory stimuli embedded in a backward masking paradigm. We identified two prestimulus EEG signatures predictive for a suprathreshold yet weak target stimulus to become perceptually resistant against masking by a stronger distractor stimulus: (i) over left frontal cortex a desynchronization of the regional beta rhythm (20 Hz) 500 msec prior to a perceived target, and (ii) a subsequent additional attenuation of both mu (10 Hz) and beta "idling" rhythms over those pericentral sensorimotor corticeswhich are going to process the upcoming target stimulus. Furthermore, across subjects the probability for target perception strongly correlates with the individual absolute level of pretarget amplitudes in these frequency bands and location s. These signatures significantly differed from the EEG characteristics preceding detected and undetected single stimuli. We suggest that the early activation of left frontal areas involved in top-down attentional control is critical for preventing backward masking and leads the preparation of primary sensory cortices: The ensuing prestimulus suppression of sensory idling rhythms warrants an intensified poststimulus processing, and thus, effectively promotes conscious perception of suprathreshold target stimuli embedded into an ecologically relevant condition featuring competing environmental stimuli.

: http://publica.fraunhofer.de/dokumente/N-169176.html