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Chan, R.

Publications and source records attributed to Chan, R..

2 recordsLinked to original sources

Weighted Network Density Predicts Range of Latent Variable Model Accuracy

Current experimental techniques impose spatial limits on the number of neuronal units that can be recorded in-vivo. To model the neural dynamics utilizing these sampled data, Latent Variable Models (LVMs) have been proposed to study the common unobserved processes within the system that drives neural activities, through an implicit network with hidden states. Yet, relationships between these latent variable models and widely-studied network connectivity measures remained unclear. In this paper, a biologically plausible latent variable model was first fit to neural activity recorded via 2-photon microscopic calcium imaging in the murine primary visual cortex. Graph theoretic measures were then applied to quantify network properties in the recorded sub-regions. Comparison of weighted network measures with LVM prediction accuracy shows some network measures having a strong relationship with LVM prediction accuracy, while other measures do not have a robust relationship with LVM prediction accuracy. Results show LVM will achieve high accuracy in dense networks.

neuroscience

Long-term dysbiosis promotes insulin resistance during obesity despite rapid diet-induced changes in the gut microbiome of mice

The intestinal microbiota and insulin sensitivity are rapidly altered in response to a high fat diet (HFD). It is unclear if gut dysbiosis precedes insulin resistance or vice versa. The initial triggers of diet-induced insulin resistance can differ from mechanisms underlying chronic dysglycemia during prolonged obesity. It is not clear if intestinal dysbiosis contributes to insulin resistance during short-term or long-term HFD-feeding. We found that diet-induced changes in the composition of the fecal microbiome preceded changes in glucose and insulin tolerance at both the onset and removal of a HFD in mice. Dysbiosis occurred after 1-3 days of HFD-feeding, whereas insulin and glucose intolerance manifested by 3-4 days. Antibiotic treatment did not alter glucose tolerance during this short-term HFD period. Conversely, antibiotics improved glucose tolerance in mice with protracted obesity caused by long-term HFD feeding for over 2 months. We also found that microbiota transmissible glucose intolerance only occurred after prolonged diet-induced dysbiosis. Germ-free mice had impaired glucose tolerance when reconstituted with the microbiota from long-term, but not short-term HFD-fed animals. Our results are consistent with intestinal microbiota contributing to chronic insulin resistance and dysglycemia during prolonged obesity, despite rapid diet-induced changes in the taxonomic composition of the fecal microbiota.

biochemistry