Distributed networks of brain areas interact with one another in a time-varying fashion to enable complex cognitive and sensorimotor functions. Here we used new network-analysis algorithms to test the recruitment and integration of large-scale functional neural circuitry during learning. Using functional magnetic resonance imaging data acquired from healthy human participants, we investigated changes in the architecture of functional connectivity patterns that promote learning from initial training through mastery of a simple motor skill. Our results show that learning induces an autonomy of sensorimotor systems and that the release of cognitive control hubs in frontal and cingulate cortices predicts individual differences in the rate of learning on other days of practice. Our general statistical approach is applicable across other cognitive domains and provides a key to understanding time-resolved interactions between distributed neural circuits that enable task performance.

Adult human cognition is supported by systems of brain regions, or modules, that are functionally coherent at rest and collectively activated by distinct task requirements. However, an understanding of how the formation of these modules supports evolving cognitive capabilities has not been delineated. Here, we quantify the formation of network modules in a sample of 780 youth (aged 8-22 y) who were studied as part of the Philadelphia Neurodevelopmental Cohort. We demonstrate that the brain's functional network organization changes in youth through a process of modular evolution that is governed by the specific cognitive roles of each system, as defined by the balance of within-vs. between-module connectivity. Moreover, individual variability in these roles is correlated with cognitive performance. Collectively, these results suggest that dynamic maturation of network modules in youth may be a critical driver for the development of cognition.neurodevelopment | graph theory | network science | modularity | brain network T he human brain is composed of large-scale functional networks that are coherent at rest, forming identifiable modules that support specific cognitive functions (1-3). These modules include well-known subsystems, such as the default-mode, visual, motor, auditory, attention, salience, and cognitive control systems. Prior research has shown that this modular structure evolves considerably during development in youth (4, 5) and across the life span (6, 7). Network modularity, a measure of the segregation between modules, is high during young adulthood and decreases across the latter life span (6, 7). Other features of network reorganization accompany development (8), including a growing preference for interactions between hubs and nonhubs (9), and between regions separated by large physical distances (10).Although prior research has explored such changes in gross network features, it remains unknown how the relationships between specific types of cognitive systems evolve during adolescent development. Ongoing developmental changes in connectivity between cognitive systems are suggested by known differences in how these systems are organized in the adult brain: Primary motor and sensory systems display a high degree of segregation with limited connections to other modules, whereas higher order cognitive systems have more between-module connectivity (1). Moreover, the disparate connectivity profiles of such systems may be critical for optimal cognitive functioning (11). Differentiation of specific network modules may thus support the burgeoning cognitive, emotional, and motor capabilities seen during adolescence (12). Furthermore, abnormalities in functional network organization are a ubiquitous finding in major neuropsychiatric conditions (11), which are increasingly considered disorders of neurodevelopment (13). Thus, a quantitative characterization of the modular maturation of functional networks in youth is critical to understanding the development of both normal and abnormal brain function.Here, w...

The human body is a complex organism, the gross mechanical properties of which are enabled by an interconnected musculoskeletal network controlled by the nervous system. The nature of musculoskeletal interconnection facilitates stability, voluntary movement, and robustness to injury. However, a fundamental understanding of this network and its control by neural systems has remained elusive. Here we address this gap in knowledge by utilizing medical databases and mathematical modeling to reveal the organizational structure, predicted function, and neural control of the musculoskeletal system. We constructed a highly simplified whole-body musculoskeletal network in which single muscles connect to multiple bones via both origin and insertion points. We demonstrated that, using this simplified model, a muscle’s role in this network could offer a theoretical prediction of the susceptibility of surrounding components to secondary injury. Finally, we illustrated that sets of muscles cluster into network communities that mimic the organization of control modules in primary motor cortex. This novel formalism for describing interactions between the muscular and skeletal systems serves as a foundation to develop and test therapeutic responses to injury, inspiring future advances in clinical treatments.

Brain development during adolescence is marked by substantial changes in brain structure and function, leading to a stable network topology in adulthood. However, most prior work has examined the data through the lens of brain areas connected to one another in large-scale functional networks. Here, we apply a recently developed hypergraph approach that treats network connections (edges) rather than brain regions as the unit of interest, allowing us to describe functional network topology from a fundamentally different perspective. Capitalizing on a sample of 780 youth imaged as part of the Philadelphia Neurodevelopmental Cohort, this hypergraph representation of resting-state functional MRI data reveals three distinct classes of subnetworks (hyperedges): clusters, bridges, and stars, which respectively represent homogeneously connected, bipartite, and focal architectures. Cluster hyperedges show a strong resemblance to previously-described functional modules of the brain including somatomotor, visual, default mode, and salience systems. In contrast, star hyperedges represent highly localized subnetworks centered on a small set of regions, and are distributed across the entire cortex. Finally, bridge hyperedges link clusters and stars in a core-periphery organization. Notably, developmental changes within hyperedges are ordered in a similar core-periphery fashion, with the greatest developmental effects occurring in networked hyperedges within the functional core. Taken together, these results reveal a novel decomposition of the network organization of human brain, and

Aphis gossypii Glover is one of the most important pests in cotton seedling. The specialized mouthpart and short generation time allow them seriously restricted the quality and yield of cotton. With the electrical penetration graph (EPG), optical microscope, and scanning electron microscope, the physical characteristics of trichomes on the cotton leaf surface and their effects on the feeding behaviors of cotton aphids were investigated in this study. Two types of leaf trichomes, glandular trichomes, and asteroid non-glandular trichomes were observed on the surface of cotton leaves under optical and scanning electron microscopes. As a whole, EPG results mainly showed differences in a non-probe waveform which meant searching on the leaf surface, and a potential drop waveform which meant intracellular penetration. Whereas pathway waveform, xylem waveform, and phloem waveform showed inconspicuous differences. Detailed indicators were slightly different at different periods. Our results confirmed that the structure of trichomes may directly affect the searching behaviors of herbivorous insect pests and hence regulate the plant-environment interactions.

Aphis gossypii Glover is one of the most important pests in cotton seedling. The specialized mouthpart and short generation time made them seriously restricted the cotton yield. With the electrical penetration graph (EPG), optical microscope, and scanning electron microscope, the physical characteristics of trichomes on the cotton leaf surface and their effects on the stylet penetration behaviors of cotton aphids were investigated in this study. Two types of leaf trichomes, glandular trichomes, and asteroid non-glandular trichomes were observed on the surface of cotton leaves under optical and scanning electron microscopes. As a whole, EPG results mainly showed differences in non-probing period which meant searching on the leaf surface, and potential drop waveform which meant intracellular punctures. Whereas pathway waveform, xylem ingestion waveform, and phloem ingestion waveform showed inconspicuous differences. Detailed indicators were slightly different at different periods. Our results suggested that the structure of trichomes may affect the searching behaviors of herbivorous insect pests and hence regulate the plant-environment interactions.

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In order to provide more evidence for the evaluation of the ecological risks of transgenic maize, arthropod population dynamics and biodiversity in fields planted with two kinds of transgenic maize (DBN9868, expressing the PAT and EPSPS genes, and DBN9936, expressing the Cry1Ab and EPSPS gene) were investigated by direct observation and trapping for three years. The recorded arthropod species belonged to 19 orders and 87 families, including Aphidoidea, Chrysomelidae, Coccinellidae, Chrysopidae and Araneae. The species richness, Shannon–Wiener diversity index, Pielou evenness index, dominance index and community similarity index of arthropod communities in maize fields were statistically analyzed, and the results showed that (1) the biodiversity difference of arthropod communities between transgenic maize and non-transgenic maize was smaller than that between different conventional cultivars; (2) the differences between ground-dwelling arthropod communities were less obvious than those between plant-inhabiting arthropod communities; and (3) Lepidoptera, the target pests of Bt maize, were not the dominant population in maize fields, and the dominant arthropod population in maize fields varied greatly between years and months. Combining those results, we concluded that the transgenic maize DBN9868 and DBN9936 had no significant effect on the arthropod communities in the field.