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> Neural synchrony and conscious perception, EEG gamma oscillations correlate with conscious perception
Orbz
post Mar 19, 2007, 05:51 PM
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From: J Neurosci. 2007 Mar 14;27(11):2858-65
# Melloni L,
# Molina C,
# Pena M,
# Torres D,
# Singer W,
# Rodriguez E

Subliminal stimuli can be deeply processed and activate similar brain areas as consciously perceived stimuli. This raises the question which signatures of neural activity critically differentiate conscious from unconscious processing. Transient synchronization of neural activity has been proposed as a neural correlate of conscious perception. Here we test this proposal by comparing the electrophysiological responses related to the processing of visible and invisible words in a delayed matching to sample task. Both perceived and nonperceived words caused a similar increase of local (gamma) oscillations in the EEG, but only perceived words induced a transient long-distance synchronization of gamma oscillations across widely separated regions of the brain. After this transient period of temporal coordination, the electrographic signatures of conscious and unconscious processes continue to diverge. Only words reported as perceived induced (1) enhanced theta oscillations over frontal regions during the maintenance interval, (2) an increase of the P300 component of the event-related potential, and (3) an increase in power and phase synchrony of gamma oscillations before the anticipated presentation of the test word. We propose that the critical process mediating the access to conscious perception is the early transient global increase of phase synchrony of oscillatory activity in the gamma frequency range.
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Orbz
post Mar 19, 2007, 05:54 PM
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They conlude:

"Therefore, we consider it likely that the key event mediating access to consciousness is the early long-distance synchronization of neural assemblies, rather than the mere depth of processing in the various cortical areas involved in written word processing."


It seems that this high frequency long distance synchronization is important somehow, does anybody know specifically how this happens?
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lucid_dream
post Mar 19, 2007, 06:19 PM
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fascinating paper! Be careful, though, Wolfgang Singer is not completely objective about the importance of neural synchrony, so it's possible that this is something of a propaganda piece from him. I know science is supposed to be objective and all, but in reality, it's the product of a bunch of people, each with their own agendas.
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Orbz
post Mar 19, 2007, 08:06 PM
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Thanks, it's a new area I'm getting into and its good to know who's into what.
I'll look him up.
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