Biology subjects

Coppola, P.

Publications and source records attributed to Coppola, P..

6 recordsLinked to original sources

bioRxiv2024

The neural correlates of shared and individual experience

Contemporary neuroscience research typically focuses on shared contents of experience and common neural states. Conversely, we set out to explore the neural correlates of individual- specific experiences that shape the distinct traits of each person. We propose an approach through which we compute individual-specific dynamics of functional connectivity states. These dynamics do not require estimation of common states across individuals and can be directly related to dynamic behavioural ratings of subjective experience. To this end, we leverage a unique functional magnetic resonance imaging dataset where subjects listened to an engaging naturalistic story while awake and under different levels of anaesthesia, altering or abolishing conscious experience. We find that this method can detect correspondences between neural and subjective dynamics. We then show that the dynamics of the default mode network underlie more personal experiences of the story as they are more dissimilar between participants during awareness compared to unconsciousness. On the other hand, the auditory and posterior dorsal attention networks show higher inter-subject similarity in consciousness compared to unconsciousness and suggest that the dynamics of these networks support more "generalisable" experiences of the story. We further characterise individual-specific brain dynamics by showing that they are associated with higher complexity in consciousness, whilst conversely, brain dynamics underlying shared experience become less complex during the conscious experience of the story.

neuroscience↗

bioRxiv2024

A thalamic perspective of (un)consciousness in pharmacological and pathological states in humans

Currently, there is substantial ongoing discussion around the functional role of the thalamus in consciousness. What is missing in the literature, however, is a systematic investigation of the relevance of specific thalamic nuclei in pharmacologically and pathologically altered states of consciousness in humans. Using functional neuroimaging in both healthy anaesthetised volunteers and patients with disorders of consciousness (DOC), we sought to identify which specific thalamic subregions in both cohorts may be differentially significant for loss of consciousness. Our findings revealed that the pulvinar (Pu) and ventral-latero-ventral (VLV) nuclei, in anaesthesia, and the VLV, in DOC, had distinct functional connectivity patterns related to the default mode and somatomotor networks. Remarkably, among all nuclei, the Pu was found to have the strongest functional connectivity change with anaesthetic-induced loss of consciousness, while in DOC patients, we found the VLV revealed the strongest connectivity change in comparison with healthy controls. Furthermore, we provide evidence that this neural connectivity biomarker in patients also mirrors the changes observed at the behavioural level, which could have clinical implications for targeted deep brain stimulation in therapy for DOC.

neuroscience↗

bioRxiv2023

Typical and disrupted small-world architecture and regional communication in full-term and preterm infants

One fundamental property of conscious experiences is that they are both differentiated and integrated. Adult functional brain networks exhibit an elegant "small-world" architecture. This optimal architecture enables efficient and cost-effective localized information processing and information integration between long-distance regions across the brain. It remains unclear whether the functional small-world architecture is developed in neonates at birth and how this development may be altered by premature birth. To address this gap, we investigated the development of small-world architecture in neonates. To understand the effect of early neonate age on small-world architecture, we also assessed neonates born prematurely or before term-equivalent age (TEA). We used the Developing Human Connectome Project (dHCP), a large neonatal functional magnetic resonance imaging (MRI) dataset with high temporal and spatial resolution. Resting-state functional MRI data for full- term neonates (N = 278, age 41.2 weeks {+/-} 12.2 days) and preterm neonates scanned at TEA (N = 72, 40.9 weeks {+/-} 14.6 days), or before TEA (N = 70, 34.7 weeks {+/-} 12.7 days), were obtained from the dHCP, and for a reference adult group (N = 176, 22-36 years), from the Human Connectome Project. Whole-brain functional network properties were evaluated with comprehensive spatial resolution using graph theoretical analyses. Although different from the adults, small-world architecture was developed in full-term born neonates at birth. Premature neonates before TEA showed dramatic underdevelopment of small-world architecture and regional communication in 9/11 brain networks, with disruption in 32% of nodes primarily distributed within the somatomotor, dorsal attention, cingulo-opercular, and frontoparietal control network. By TEA, premature neonates showed large-scale recuperation of regional communication, with 1.4% of nodes, distributed in the frontoparietal, salience, and visual networks remaining significantly underdeveloped. Our results suggest that, at full- term birth or by term-equivalent age, infants possess well-developed small-world architecture, which facilitates differentiated and integrated neural processes that give rise to conscious experiences. Conversely, they suggest that this brain infrastructure is significantly underdeveloped before infants reach term-equivalent age. These findings improve understanding of the ontogeny of functional small-world architecture and efficiency of neural communication across distinct brain networks in infants at birth.

neuroscience↗

bioRxiv2022

Reduced emergent character of neural dynamics in patients with a disrupted connectome

High-level brain functions are widely believed to emerge from the orchestrated activity of multiple neural systems. However, lacking a formal definition and practical quantification of emergence for experimental data, neuroscientists have been unable to empirically test this long-standing conjecture. Here we investigate this fundamental question by leveraging a recently proposed framework known as "Integrated Information Decomposition," which establishes a principled information-theoretic approach to operationalise and quantify emergence in dynamical systems -- including the human brain. By analysing functional MRI data, our results show that the emergent and hierarchical character of neural dynamics is significantly diminished in chronically unresponsive patients suffering from severe brain injury. At a functional level, we demonstrate that emergence capacity is positively correlated with the extent of hierarchical organisation in brain activity. Furthermore, by combining computational approaches from network control theory and whole-brain biophysical modelling, we show that the reduced capacity for emergent and hierarchical dynamics in severely brain-injured patients can be mechanistically explained by disruptions in the patients structural connectome. Overall, our results suggest that chronic unresponsiveness resulting from severe brain injury may be due to structural impairment of the fundamental neural infrastructures required for brain dynamics to support emergence.

neuroscience↗

bioRxiv2021

Network dynamics scale with levels of awareness

Small world topologies are thought to provide a valuable insight into human brain organisation and consciousness. However, functional magnetic resonance imaging studies in consciousness have not yielded consistent results. Given the importance of dynamics for both consciousness and cognition, here we investigate how the diversity of brain dynamics pertaining to small world topology (quantified by sample entropy; dSW-E) scales with decreasing levels of awareness (i.e., sedation and disorders of consciousness). Paying particular attention to result reproducibility, we show that dSW-E is a consistent predictor of levels of awareness even when controlling for the underlying functional connectivity dynamics. We find that dSW-E of subcortical and cortical areas are predictive, with the former showing higher and more robust effect sizes across analyses. Consequently, we propose that the dynamic reorganisation of the functional information architecture, in particular of the subcortex, is a characteristic that emerges with awareness and has explanatory power beyond that of the complexity of dynamic functional connectivity.

neuroscience↗

bioRxiv2021

Paths to Oblivion: Common Neural Mechanisms of Anaesthesia and Disorders of Consciousness

The human brain generates a rich repertoire of spatiotemporal dynamics during normal wakefulness, supporting a wide variety of conscious experiences and cognitive functions. However, neural dynamics are reconfigured, in comparable ways, when consciousness is lost either due to anaesthesia or disorders of consciousness (DOC). Here, leveraging a neurobiologically realistic whole-brain computational model informed by functional MRI, diffusion MRI, and PET, we sought to identify the neurobiological mechanisms that explain the common reconfiguration of neural dynamics observed both for transient pharmacological intervention and chronic neuroanatomical injury. Our results show that, by incorporating local inhibitory action through a PET-based GABA receptor density map, our model can reproduce the brain dynamics of subjects undergoing propofol anaesthesia, and that this effect depends specifically on the spatial distribution of GABA receptors across cortical regions. Additionally, using a structural connectome obtained from DOC patients, we demonstrate how the dynamics that characterise loss of consciousness can emerge from changes in neuroanatomical connectivity. Crucially, we find that each of these two interventions generalises across datasets: a model with increased GABA-mediated inhibition can reproduce the dynamics of DOC patients brains, and a model with a DOC connectome is also compatible with brain dynamics observed during propofol anaesthesia. These results demonstrate how increased inhibition and connectome randomisation represent different neurobiological paths towards the characteristic dynamics of the unconscious brain. Overall, the present findings begin to disentangle the neurobiological mechanisms by which highly dissimilar perturbations of the brains neurodynamics can lead to unconsciousness.

neuroscience↗