Dear All
This afternoon (YNiC open plan, 4.15 pm start) Prof. Gary Green will be
giving a talk on "Connectivity maps based on linear and non-linear
dynamics".
Abstract:
Many methods have been used to provide evidence of the existence of a
connection from one brain area to another. The evidence can be from
structural investigations such as DTI and histology or from functional
investigations using techniques such as Granger Causality, coherence or
other non-causal methods. These tell us that connections exist but they
do not necessarily provide evidence of the form of the interaction both
in terms of direction, the nature of the processing or the dynamics of
the connection.
Two 'new' approaches to investigating the dynamics of connectivity
will be presented. These are the Adomian Decomposition method and the
Fliess Generating Series method. Both are highly related and are based
on functional expansions of non-linear differential models of the brain.
The can be used with standard ODEs, but can also be used with PDEs,
delay-differential and stochastics models
Both can be used to compare and eshew models, to fit models to data
and to test if existing models are supported by experiment. In passing
we show that SPM's DCM approach may suffer from highly correlated
posteriors.
The approaches are causal and can inform us about directionality,
the timing of connections as well as the level and form of
linear/non-linear processing. We have implemented them in a
simple-to-use set of modules in Python.
MEG data from a reading task will be used to demonstrate the
techniques and to show evidence that brain areas are
causally,directionally connected, on different time scales during this
task.
Everyone is welcome to attend.
Best wishes
Rebecca
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Dr. Rebecca E. Millman
Science Liaison Officer
York Neuroimaging Centre
The Biocentre
York Science Park
Heslington
YO10 5DG
Tel: +44 (0) 1904 567614
Fax: +44 (0) 1904 435356
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