Journal of Neuroscience
October 4, 2017
Melanie Boly, Marcello Massimini, Naotsugu Tsuchiya et al.
591 citations
The role of the frontal cortex in consciousness is debated. This Perspective critically reviews clinical and neuroimaging evidence for the involvement of the front versus the back of the cortex in specifying conscious contents and discusses promising research avenues.
Frontiers in Psychology
January 1, 2013
Francesca Siclari, Joshua J. LaRocque, Bradley R. Postle et al.
184 citations
Consciousness during sleep changes dramatically across the night. Seven healthy participants were awakened 15–30 minutes apart across 44 nights and asked about their most recent conscious experience before the alarm. Recall with content occurred in 34% of non-REM awakenings and 77% of REM awakenings. Each sleep stage showed a distinct profile of features including thinking, perceiving, self-relatedness, and reflective consciousness. The serial awakening method yielded a large, representative sample of sleep consciousness with minimal disruption from sleep fragmentation, and may be especially useful when combined with brain imaging techniques.
Journal of Neuroscience
February 8, 2017
Jason Samaha, Olivia Gosseries, Bradley R. Postle
131 citations
Transcranial magnetic stimulation (TMS) of occipital and posterior parietal cortex can produce visual sensations called phosphenes. Using near-threshold TMS with concurrent EEG, the authors found that prestimulus power and phase in the alpha band (8–13 Hz) predicted occipital TMS phosphenes, while higher-frequency beta-band (13–20 Hz) power (but not phase) predicted parietal TMS phosphenes. TMS-evoked responses related to phosphene perception were similar across sites, showing an early posterior negativity and later parietal positivity, plus low-frequency power increase followed by broadband alpha/beta power decrease. These correlates resemble those of conscious perception of near-threshold visual stimuli. The regionally differential prestimulus predictors suggest distinct frequencies reflect cortical excitability in occipital versus parietal cortex, challenging the assumption that alpha rhythm serves as a general index of cortical excitability.
Scientific Reports
March 26, 2019
Minji Lee, Benjamin Baird, Olivia Gosseries et al.
98 citations
During non-rapid eye movement sleep, conscious experiences are linked to reduced phase-locking at low frequencies (<4 Hz) and lower transitivity and clustering coefficient in delta and theta bands compared to unconsciousness, especially over parietal-occipital regions. No significant differences in Granger-causality patterns between frontal and parietal areas were found. These findings suggest that decreased local connectivity at low frequencies in posterior brain regions may indicate consciousness during sleep.
Scientific Reports
August 5, 2016
Jaakko O. Nieminen, Olivia Gosseries, Marcello Massimini et al.
60 citations
During non-rapid eye movement (NREM) sleep, the brain's response to transcranial magnetic stimulation (TMS) differs depending on whether the person is conscious (dreaming) or not. When subjects reported no conscious experience upon awakening, TMS evoked a larger negative deflection and a shorter phase-locked response compared to when they reported a dream. The amplitude of the negative deflection—a hallmark of neuronal bistability—was inversely correlated with the length of the dream report. These findings suggest that variations in the level of consciousness within the same physiological state are associated with changes in underlying cortical bistability.
bioRxiv Preprint Server
March 19, 2017
Melanie Boly, Marcello Massimini, Naotsugu Tsychiya et al.
56 citations
preprint
The role of the frontal cortex in consciousness is debated. This perspective critically reviews clinical and neuroimaging evidence on whether the front or back of the cortex specifies conscious contents, and discusses promising research avenues. The authors argue that current evidence does not clearly support a primary role for the frontal cortex in generating conscious experience, pointing instead to posterior regions as more directly involved. They suggest that future research should focus on distinguishing neural correlates of consciousness from prerequisites and consequences.