| dc.description.abstract |
<p>Many biological processes are effectively modeled as networks, but a frequent assumption
is that these networks do not change during data collection. However, that assumption
does not hold for many phenomena, such as neural growth during learning or changes
in genetic regulation during cell differentiation. Approaches are needed that explicitly
model networks as they change in time and that characterize the nature of those changes.</p><p>In
this work, we develop a new class of graphical models in which the conditional dependence
structure of the underlying data-generation process is permitted to change over time.
We first present the model, explain how to derive it from Bayesian networks, and develop
an efficient MCMC sampling algorithm that easily generalizes under varying levels
of uncertainty about the data generation process. We then characterize the nature
of evolving networks in several biological datasets.</p><p>We initially focus on learning
how neural information flow networks change in songbirds with implanted electrodes.
We characterize how they change in response to different sound stimuli and during
the process of habituation. We continue to explore the neurobiology of songbirds
by identifying changes in neural information flow in another habituation experiment
using fMRI data. Finally, we briefly examine evolving genetic regulatory networks
involved in Drosophila muscle differentiation during development.</p><p>We conclude
by suggesting new experimental directions and statistical extensions to the model
for predicting novel neural flow results.</p>
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