Synchronization of Neural Activity across Cortical Areas Correlates with Conscious Perception

By Lucia Melloni, C. Molina, M. Peña, D. Torres, Wolf Singer, Eugenio Rodríguez. Journal of Neuroscience, 2007

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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.

Subfields: Cognitive Neuroscience

View Paper: https://www.semanticscholar.org/paper/b2ac15db0b7829efcb8dcbda723039a3df2b6f11

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In Cognitive Neuroscience

Citations in the corpus

Prestimulus oscillations predict visual perception performance between and within subjects (2007, background): “A recent study by Melloni et al. (2007) showed that stimulus-induced long-range gamma synchrony (around 40 Hz) was positively correlated with conscious visual perception.”
Brain Dynamics Underlying the Nonlinear Threshold for Access to Consciousness (2007, methodology): “We therefore cannot exclude that a more sensitive method such as single-cell recording or phase synchrony analysis would reveal consciousness-related events prior to the present suggested onset time of 270 ms [58].”
How can we measure awareness? An overview of current methods (2015, background): “…rather than corresponding exclusively to the phenomenology of awareness (the NCC), may also reflect processes that precede or follow conscious perception—its causes and consequences (Pins and Ffytche 2003; Del Cul et al. 2007; Melloni et al. 2007; Aru and Bachmann 2009a, b; Gaillard et al. 2009).”
Inter-Brain Synchronization during Social Interaction (2010, neutral): “Within one brain, synchronous neural oscillations have been previously observed in a range of processes such as conscious perception [44–46], working and long term memory [47,48], states of anticipation or attention [48,49] and empathy [50].”
Computational models of schizophrenia and dopamine modulation in the prefrontal cortex (2008, background): “…of frequencies in patients with schizophrenia ( broadband phase synchrony ) raises the possibility that there are intrinsic deficits in the brain circuitry that supports oscillations in several frequency bands (perhaps indicating increased noise in spiking neurons, as outlined above) 102–106 .”
Dynamic coordination in the brain : from neurons to mind (2010, background): “Both synchrony and high-frequency (gamma and beta) rhythms have been implicated in attention, short-term memory, associative memory, sensory-motor coordination, consciousness, and learning (Singer 2004; Melloni et al. 2007; Wespatat et al. 2004).”
Scaling Brain Size, Keeping Timing: Evolutionary Preservation of Brain Rhythms (2013, neutral): “, 2003), between entorhinal cortex and hippocampus (Chrobak and Buzsáki, 1998), and between remote regions of the cerebral cortex (Gregoriou et al., 2009; Melloni et al., 2007).”
EEG and MEG: relevance to neuroscience. (2013, neutral): “…signals have been published supporting the assertion that neurophysiological processesmediating conscious perception involve transient increases of phase synchrony of oscillations in the g band (Tallon-Baudry et al., 1996; Melloni et al., 2007; Doesburg et al., 2009; Fahrenfort et al., 2012).”
A taxonomy of external and internal attention. (2011, neutral): “Global awareness is correlated with long-distance synchronization of gamma oscillations across widely separated brain regions (Melloni et al. 2007, Womelsdorf et al. 2007).”
The hippocampal indexing theory and episodic memory: Updating the index (2007, background): “Strengthening connections among ensembles of neocortical neurons may also be associated with high frequency activity associated with perceptual binding (Melloni et al., 2007) and bursts of activity during sleep (Battaglia et al.”
Experimental and theoretical approaches to conscious processing. (2011, background): “…1995; Lamme et al., 2002; Rolls et al., 1999) and by essentially all recent ERP and MEG studies (Dehaene et al., 2001; Del Cul et al., 2007; Fahrenfort et al., 2007; Koivisto et al., 2006, 2009; Lamy et al., 2009; Melloni et al., 2007; Railo and Koivisto, 2009; van Aalderen-Smeets et al., 2006).”
A Review on the Computational Methods for Emotional State Estimation from the Human EEG (2013, background): “In short, a brief summary of the EEG correlates of emotion is presented in Table 1.”