Disrupted stepwise functional brain organization in overweight individuals

Functional hierarchy establishes core axes of the brain, and overweight individuals show alterations in the networks anchored on these axes, particularly in those involved in sensory and cognitive control systems. However, quantitative assessments of hierarchical brain organization in overweight individuals are lacking. Capitalizing stepwise functional connectivity analysis, we assess altered functional connectivity in overweight individuals relative to healthy weight controls along the brain hierarchy. Seeding from the brain regions associated with obesity phenotypes, we conduct stepwise connectivity analysis at different step distances and compare functional degrees between the groups. We find strong functional connectivity in the somatomotor and prefrontal cortices in both groups, and both converge to transmodal systems, including frontoparietal and default-mode networks, as the number of steps increased. Conversely, compared with the healthy weight group, overweight individuals show a marked decrease in functional degree in somatosensory and attention networks across the steps, whereas visual and limbic networks show an increasing trend. Associating functional degree with eating behaviors, we observe negative associations between functional degrees in sensory networks and hunger and disinhibition-related behaviors. Our findings suggest that overweight individuals show disrupted functional network organization along the hierarchical axis of the brain and these results provide insights for behavioral associations.

Large-Scale Intrinsic Functional Brain Organization Emerges from Three Canonical Spatiotemporal Patterns

The past decade of functional neuroimaging research has seen the application of increasingly sophisticated advanced methods to characterize intrinsic functional brain organization. Accompanying these techniques are a patchwork of empirical findings highlighting novel properties of intrinsic functional brain organization. To date, there has been little attempt to understand whether there is an underlying unity across this patchwork of empirical findings. Our study conducted a systematic survey of popular analytic techniques and their output on a large sample of resting-state fMRI data. We found that the apparent complexity of intrinsic functional brain organization can be seamlessly reduced to three fundamental low-frequency spatiotemporal patterns. Our study demonstrates that a long list of previously observed phenomena, including functional connectivity gradients, the task-positive/task-negative pattern, the global signal, time-lag propagation patterns, the quasiperiodic pattern and the network structure of the functional connectome are simply manifestations of these three spatiotemporal patterns. An in-depth characterization of these three spatiotemporal patterns using a novel time-varying complex pattern analysis revealed that these three patterns may arise from a single hemodynamic mechanism.

Large-Scale Intrinsic Functional Brain Organization Emerges from Three Canonical Spatiotemporal Patterns

The characterization of intrinsic functional brain organization has been approached from a multitude of analytic techniques and methods. We are still at a loss of a unifying conceptual framework for capturing common insights across this patchwork of empirical findings. By analyzing resting-state fMRI data from the Human Connectome Project using a large number of popular analytic techniques, we find that all results can be seamlessly reconciled by three fundamental low-frequency spatiotemporal patterns that we have identified via a novel time-varying complex pattern analysis. Overall, these three spatiotemporal patterns account for a wide variety of previously observed phenomena in the resting-state fMRI literature including the task-positive/task-negative anticorrelation, the global signal, the primary functional connectivity gradient and the network community structure of the functional connectome. The shared spatial and temporal properties of these three canonical patterns suggest that they arise from a single hemodynamic mechanism.

Innate Organization of the Human Brain

The adult brain is organized into distinct functional networks, forming the basis of information processing and determining individual differences in behavior. Is this network organization genetically determined and present at birth? Here, we use unsupervised learning to uncover intrinsic functional brain organization using resting-state connectivity from a large cohort of neonates (Developing Human Connectome Project). We identified a set of symmetric, hierarchical, and replicable networks: sensorimotor, visual, default mode, ventral attention, and high-level vision. We also quantified neonate individual variability, finding low variability for sensorimotor, but high for ventral attention networks. These neonate networks resembled adult networks (Yeo et al., 2011), but frontoparietal and limbic networks found in adults were indiscernible in neonates. Finally, differential gene expression provided a potential explanation for the emergence of these distinct networks. Our results reveal the basic proto-organization of cortex at birth, but indicate a role for maturation and experience in developing adult-like functional brain organization.

Sports and Lateralization of Visual Spatial Attention: A Comparative Study of Practitioners of Foot Orienteering, Judo Wrestlers and Non-Athletes

Performance in all sports requires good spatial attention. This study investigates the impact of long-term sports training on lateralization of visual spatial attention and also explores if the type of sport (foot orienteering (FootO) vs. judo) could be related to differentiated effects on the pattern of lateralization. Thirty practitioners of FootO (aged 16-58 years, Mean age = 24.96±10.98; 16 males), 30 judo wrestlers (aged 16-60 years, Mean age = 25.96±10.61; 19 males), and 30 subjects who have never practiced any sport (aged 15-53 years, Mean age = 33.2±11.56; 13 males), were studied with a line-bisection task. All participants were right-handed and the athletes had at least 5 years of active sport practicing. Although the mean transection in the three groups was to the left of the true center regardless of the hand used suggesting right pseudoneglect, the accuracy of both hands was highest in the group of practitioners of FootO and lowest in the non-athletes group. Also, there were no between-hands differences in the accuracy among practitioners of FootO (t(30) = 0.062, p = 0.951), slightly better right hand accuracy in judo wrestlers (t(30) = 0.608, p = 0.548), and significantly better right hand accuracy in non-athletes (t(30) = -2.297, p = 0.029). In general, the results suggest that the active long-term training of any sport may affects functional brain organization of visual spatial attention towards its more balanced hemispheric presentation, but the type of sport is of great importance for the magnitude of the induced changes.

Assessing the degree of ecological validity of your study: Introducing the Ecological Validity Assessment (EVA) Tool

In cognitive neurosciences, fundamental principles of mental processes and functional brain organization have been established with highly controlled tasks and testing environments. Recent technical advances allowed to investigate those functions and their brain mechanisms in naturalistic settings. The diversity in those approaches has been recently (Matusz et al. 2019a) classified via a three-stage cycle including controlled laboratory, partially naturalistic laboratory, and naturalistic real-world research. Based on this cycle, we developed the Ecological Validity Assessment (EVA) tool to inform in an easy manner about the approach researchers have taken in their study. It enables objectively describing the study’s degree of ecological validity and its location on the cycle. EVA comprises eleven questions concerning study’s characteristics. It outputs a summary of those and a compass plot, which can be used for presentations, pre-registration, grant proposals, and papers. It would improve drawing conclusions across studies, and raising awareness for the generalizability of studies.

Handedness and White Matter Networks

The development and persistence of laterality is a key feature of human motor behavior, with the asymmetry of hand use being the most prominent. The idea that asymmetrical functions of the hands reflect asymmetries in terms of structural and functional brain organization has been tested many times. However, despite advances in laterality research and increased understanding of this population-level bias, the neural basis of handedness remains elusive. Recent developments in diffusion magnetic resonance imaging enabled the exploration of lateralized motor behavior also in terms of white matter and connectional neuroanatomy. Despite incomplete and partly inconsistent evidence, structural connectivity of both intrahemispheric and interhemispheric white matter seems to differ between left and right-handers. Handedness was related to asymmetry of intrahemispheric pathways important for visuomotor and visuospatial processing (superior longitudinal fasciculus), but not to projection tracts supporting motor execution (corticospinal tract). Moreover, the interindividual variability of the main commissural pathway corpus callosum seems to be associated with handedness. The review highlights the importance of exploring new avenues for the study of handedness and presents the latest state of knowledge that can be used to guide future neuroscientific and genetic research.

Subtypes of functional connectivity associate robustly with ASD diagnosis

Our understanding of the changes in functional brain organization in autism is hampered by the extensive heterogeneity that characterizes this neurodevelopmental disorder. Data driven clustering offers a straightforward way to decompose this heterogeneity into subtypes of distinguishable connectivity types and promises an unbiased framework to investigate behavioural symptoms and causative genetic factors. Yet the robustness and generalizability of these imaging subtypes is unknown. Here, we show that unsupervised functional connectivity subtypes are moderately associated with the clinical diagnosis of autism, and that these associations generalize to independent replication data. We found that subtypes identified robust patterns of functional connectivity, but that a discrete assignment of individuals to these subtypes was not supported by the data. Our results support the use of data driven subtyping as a data dimensionality reduction technique, rather than to establish clinical categories.