Wintherbatchelor5410

We also find evidence that activity is lower and more sparse for empirical networks compared to degree-matched randomized networks under IS, suggesting that brain network topology supports IS-like routing strategies.Having a structural network representation of connectivity in the brain is instrumental in analyzing communication dynamics and neural information processing. In this work, we make steps towards understanding multisensory information flow and integration using a network diffusion approach. In particular, we model the flow of evoked activity, initiated by stimuli at primary sensory regions, using the asynchronous linear threshold (ALT) diffusion model. The ALT model captures how evoked activity that originates at a given region of the cortex "ripples through" other brain regions (referred to as an activation cascade). We find that a small number of brain regions-the claustrum and the parietal temporal cortex being at the top of the list-are involved in almost all cortical sensory streams. This suggests that the cortex relies on an hourglass architecture to first integrate and compress multisensory information from multiple sensory regions, before utilizing that lower dimensionality representation in higher level association regions and more complex cognitive tasks.The communicability distance between pairs of regions in human brain is used as a quantitative proxy for studying Alzheimer's disease. Using this distance, we obtain the shortest communicability path lengths between different regions of brain networks from patients with Alzheimer's disease (AD) and healthy cohorts (HC). We show that the shortest communicability path length is significantly better than the shortest topological path length in distinguishing AD patients from HC. Based on this approach, we identify 399 pairs of brain regions for which there are very significant changes in the shortest communicability path length after AD appears. We find that 42% of these regions interconnect both brain hemispheres, 28% connect regions inside the left hemisphere only, and 20% affect vermis connection with brain hemispheres. These findings clearly agree with the disconnection syndrome hypothesis of AD. Finally, we show that in 76.9% of damaged brain regions the shortest communicability path length drops in AD in relation to HC. This counterintuitive finding indicates that AD transforms the brain network into a more efficient system from the perspective of the transmission of the disease, because it drops the circulability of the disease factor around the brain regions in relation to its transmissibility to other regions.The connectome provides the structural substrate facilitating communication between brain regions. We aimed to establish whether accounting for polysynaptic communication in structural connectomes would improve prediction of interindividual variation in behavior as well as increase structure-function coupling strength. Connectomes were mapped for 889 healthy adults participating in the Human Connectome Project. To account for polysynaptic signaling, connectomes were transformed into communication matrices for each of 15 different network communication models. Communication matrices were (a) used to perform predictions of five data-driven behavioral dimensions and (b) correlated to resting-state functional connectivity (FC). While FC was the most accurate predictor of behavior, communication models, in particular communicability and navigation, improved the performance of structural connectomes. Communication also strengthened structure-function coupling, with the navigation and shortest paths models leading to 35-65% increases in association strength with FC. We combined behavioral and functional results into a single ranking that provides insight into which communication models may more faithfully recapitulate underlying neural signaling patterns. Comparing results across multiple connectome mapping pipelines suggested that modeling polysynaptic communication is particularly beneficial in sparse high-resolution connectomes. We conclude that network communication models can augment the functional and behavioral predictive utility of the human structural connectome.Communication models describe the flow of signals among nodes of a network. In neural systems, communication models are increasingly applied to investigate network dynamics across the whole brain, with the ultimate aim to understand how signal flow gives rise to brain function. Communication models range from diffusion-like processes to those related to infectious disease transmission and those inspired by engineered communication systems like the internet. This Focus Feature brings together novel investigations of a diverse range of mechanisms and strategies that could shape communication in mammal whole-brain networks.The thermal deactivation of Pd/CeO2-ZrO2 (Pd/CZ) three-way catalysts was studied via nanoscale structural characterization and catalytic kinetic analysis to obtain a fundamental modeling concept for predicting the real catalyst lifetime. selleck kinase inhibitor The catalysts were engine-aged at 600-1100 °C and used for chassis dynamometer driving test cycles. Observations using an electron microscope and chemisorption experiments showed that the Pd particle size significantly changed in the range of 10-550 nm as a function of aging temperatures. The deactivated catalyst structure was modeled using different-sized hemispherical Pd particles that were in intimate contact with the support surface. Therefore, Pd/CZ contained two types of surface Pd sites residing on the surface of a hemisphere (Pds) and circular periphery of the Pd/CZ interface (Pdb), whereas a reference catalyst, Pd/Al2O3, contained only Pds. In all Pd particle sizes investigated herein, Pd/CZ exhibited higher reaction rates than Pd/Al2O3, which nonlinearly increased with increasing slope as the weight-based number of surface-exposed Pd atoms ([Pds] + [Pdb]) increased. This finding contrasted with that of Pd/Al2O3, where the reaction rate linearly increased with [Pds]. When the Pds sites in both catalysts were equivalent in terms of their specific activities, the activity difference between Pd/CZ and Pd/Al2O3 corresponded to the contribution from Pdb, where oxygen storage/release to/from CZ played a key role. This contribution linearly increased with [Pdb] and therefore decreased with Pd sintering. Although both Pds and Pdb sites showed nearly constant turnover frequencies despite the difference in the Pd particle size, the values for Pdb were more than 2 orders of magnitude greater than those for Pds when assuming a single-atom width one-dimensional Pdb row model. These results suggest that the thermal deterioration of the three-phase boundary site, where Pd, CZ, and the gas phase meet, determines the activity under surface-controlled conditions.