A Switch and Wave of Neuronal Activity in the Cerebral Cortex During the First Second of Conscious Perception

Abstract

Conscious perception occurs within less than 1 s. To study events on this time scale we used direct electrical recordings from the human cerebral cortex during a conscious visual perception task. Faces were presented at individually titrated visual threshold for 9 subjects while measuring broadband 40-115 Hz gamma power in a total of 1621 intracranial electrodes widely distributed in both hemispheres. Surface maps and k-means clustering analysis showed initial activation of visual cortex for both perceived and non-perceived stimuli. However, only stimuli reported as perceived then elicited a forward-sweeping wave of activity throughout the cerebral cortex accompanied by large-scale network switching. Specifically, a monophasic wave of broadband gamma activation moves through bilateral association cortex at a rate of approximately 150 mm/s and eventually reenters visual cortex for perceived but not for non-perceived stimuli. Meanwhile, the default mode network and the initial visual cortex and higher association cortex networks are switched off for the duration of conscious stimulus processing. Based on these findings, we propose a new "switch-and-wave" model for the processing of consciously perceived stimuli. These findings are important for understanding normal conscious perception and may also shed light on its vulnerability to disruption by brain disorders.

Electrophysiological dynamics of antagonistic brain networks reflect attentional fluctuations

“…The relatively late suppression of the DMN relative to activation in other association networks suggest a temporal hierarchy that may accord well with findings that situate DMN regions as those with longest connectivity paths and furthest geodesic distance from primary sensory regions 50 . Moreover, our findings accord with other iEEG studies showing relatively late DMN task-evoked responses 29,51 as well as with work suggesting that temporal receptive windows are prolonged within DMN compared with other higher-order association regions 52,53 .…”

Phase‐dependent modulation of cortical and thalamic sensory responses during spike‐and‐wave discharges

“…In this view, it has been shown in a recent study, conducted on epileptic patients implanted with widely distributed subdural and intracranial EEG electrodes, that consciously perceived and not consciously perceived visual stimuli could both activate the primary visual cortex but that only perceived stimuli were accompanied by a temporally organized sequence of gamma activity increases in brain networks subtending conscious processing. 56 This is also consistent with the detection of auditory responses in the primary auditory cortex of patients in a vegetative state, whereas the related higher-order association cortices failed to be activated. 57 Some previous theories have also proposed that the behavioral deficits during absences could be caused by a global disruption of normal information processing in specialized subcortical and cortical brain regions serving sensory perception.…”

“…As an additional mechanism, the residual integration of sensory inputs by primary cortical areas during SWDs might not be sufficient to initiate the large‐scale integrative processes required to produce awareness. In this view, it has been shown in a recent study, conducted on epileptic patients implanted with widely distributed subdural and intracranial EEG electrodes, that consciously perceived and not consciously perceived visual stimuli could both activate the primary visual cortex but that only perceived stimuli were accompanied by a temporally organized sequence of gamma activity increases in brain networks subtending conscious processing . This is also consistent with the detection of auditory responses in the primary auditory cortex of patients in a vegetative state, whereas the related higher‐order association cortices failed to be activated .…”

The relationship between attention and consciousness: an expanded taxonomy and implications for ‘no-report’ paradigms

“…As a third example, HOTs are based on the idea that sensory representations themselves (first-order processes) are not sufficient for consciousness because such representations Busch et al [92] Eo et al [94] Fahrenfort et al [81] Frässle et al [91] Herman et al [82] Koivisto & Revonsuo [89] Pitts et al [77] previous studies zero full minimal stimulus strength attention 1 Pitts et al [80] Sergent et al [90] Wilke et al [93] 2 3 4 5 6 Figure 2. Examples of previous studies that have explored the space depicted in figure 1.…”