The envirome and the connectome: exploring the structural noise in the human brain associated with socioeconomic deprivation

Complex cognitive functions are widely recognized to be the result of a number of brain regions working together as large-scale networks. Recently, complex network analysis has been used to characterize various structural properties of the large scale network organization of the brain. For example, the human brain has been found to have a modular architecture i.e. regions within the network form communities (modules) with more connections between regions within the community compared to regions outside it. The aim of this study was to examine the modular and overlapping modular architecture of the brain networks using complex network analysis. We also examined the association between neighborhood level deprivation and brain network structure – modularity and grey nodes. We compared network structure derived from anatomical MRI scans of 42 middle-aged neurologically healthy men from the least (LD) and the most deprived (MD) neighborhoods of Glasgow with their corresponding random networks. Cortical morphological covariance networks were constructed from the cortical thickness derived from the MRI scans of the brain. For a given modularity threshold, networks derived from the MD group showed similar number of modules compared to their corresponding random networks, while networks derived from the LD group had more modules compared to their corresponding random networks. The MD group also had fewer grey nodes – a measure of overlapping modular structure. These results suggest that apparent structural difference in brain networks may be driven by differences in cortical thicknesses between groups. This demonstrates a structural organization that is consistent with a system that is less robust and less efficient in information processing. These findings provide some evidence of the relationship between socioeconomic deprivation and brain network topology

Critical brain networks

Highly correlated brain dynamics produces synchronized states with no behavioral value, while weakly correlated dynamics prevents information flow. We discuss the idea put forward by Per Bak that the working brain stays at an intermediate (critical) regime characterized by power-law correlations.Comment: Contribution to the Niels Bohr Summer Institute on Complexity and Criticality (2003); to appear in a Per Bak Memorial Issue of PHYSICA

Structure and Dynamics of Brain Lobes Functional Networks at the Onset of Anesthesia Induced Loss of Consciousness

Anesthetic agents are neurotropic drugs able to induce dramatic alterations in the thalamo-cortical system, promoting a drastic reduction in awareness and level of consciousness. There is experimental evidence that general anesthesia impacts large scale functional networks leading to alterations in the brain state. However, the way anesthetics affect the structure assumed by functional connectivity in different brain regions have not been reported yet. Within this context, the present study has sought to characterize the functional brain networks respective to the frontal, parietal, temporal and occipital lobes. In this experiment, electro-physiological neural activity was recorded through the use of a dense ECoG-electrode array positioned directly over the cortical surface of an old world monkey of the species Macaca fuscata. Networks were serially estimated over time at each five seconds, while the animal model was under controlled experimental conditions of an anesthetic induction process. In each one of the four cortical brain lobes, prominent alterations on distinct properties of the networks evidenced a transition in the networks architecture, which occurred within about one and a half minutes after the administration of the anesthetics. The characterization of functional brain networks performed in this study represents important experimental evidence and brings new knowledge towards the understanding of neural correlates of consciousness in terms of the structure and properties of the functional brain networks.Comment: 41 pages; 30 figures; 30 tables. arXiv admin note: substantial text overlap with arXiv:1604.0000