Functional diversity of brain networks supports consciousness and verbal intelligence

Abstract

How are the myriad stimuli arriving at our senses transformed into conscious thought? To address this question, in a series of studies, we asked whether a common mechanism underlies loss of information processing in unconscious states across different conditions, which could shed light on the brain mechanisms of conscious cognition. With a novel approach, we brought together for the first time, data from the same paradigm—a highly engaging auditory-only narrative—in three independent domains: anesthesia-induced unconsciousness, unconsciousness after brain injury, and individual differences in intellectual abilities during conscious cognition. During external stimulation in the unconscious state, the functional differentiation between the auditory and fronto-parietal systems decreased significantly relatively to the conscious state. Conversely, we found that stronger functional differentiation between these systems in response to external stimulation predicted higher intellectual abilities during conscious cognition, in particular higher verbal acuity scores in independent cognitive testing battery. These convergent findings suggest that the responsivity of sensory and higher-order brain systems to external stimulation, especially through the diversification of their functional responses is an essential feature of conscious cognition and verbal intelligence.

Network dynamics scale with levels of awareness

“…Previously, changes in static (Di Perri et al, 2016;Naci et al, 2018;Stamatakis et al, 2010) and dynamic functional connectivity (Barttfeld et al, 2015;Cavanna et al, 2018;Demertzi et al, 2019;Golkowski et al, 2019) in different states of consciousness have been widely reported. We advance .…”

“…Due to equipment malfunction or impairments with the anaesthetic procedure three participants were excluded (1 male). Thus, 16 participants were included in this study (Naci et al, 2018).…”

“…The empirical data consists of three independent functional magnetic resonance imaging (fMRI) datasets that are relevant to consciousness. Two are propofol anaesthesia datasets; the first collected in Cambridge (referred to as "CAM" dataset onwards), UK (18 participants) comprising a control awake and a moderate sedation condition (Adapa, Davis, Stamatakis, Absalom, & Menon, 2014) and the second in London, Ontario (henceforth referred to as LON) :16 participants in control awake and deep sedation conditions (Naci et al, 2018). The third dataset was acquired from patients with disorders of consciousness (hereafter indicated by "DOC", Cambridge, UK).…”

Examining the relationship between social cognition and neural synchrony during movies in children with and without autism

“…Understanding a complex narrative (such as a movie's plot) requires a viewer to remember previous events, pay attention to what is currently happening, make predictions about the future consequences of current events, and integrate this information over time, all of which depends on frontoparietal executive processing (Naci et al, 2014). In previous studies, reduced synchrony in this network has been associated with 'losing the plot' during deep sedation (Naci et al, 2018), and in patients with severe brain damage (Naci et al, 2014). Thus, this decrease in inter-subject correlation in the lateral prefrontal cortex may suggest that participants in the ASD group are also failing to grasp elements of the plot in the way that the other participants do.…”

“…It is possible that individuals were attending to different features of the movie, which has been shown to influence the degree of neural synchrony (Nguyen et al, 2019), although previous work has confirmed that movies similar to 'Despicable me' maintain the viewers' attention (Hasson, Landesman, et al, 2008;Naci et al, 2015). It is also unlikely that participants were asleep during the movie, as most of the visual network was synchronized across the three groups during the movie, which is not observed when individuals are sedated (Naci et al, 2018).…”