Spatio-temporal Models for Mental Processes from fMRI
Speaker: Firdaus Janoos , Harvard Medical School/BWH
Date: December 2 2011
Time: 1:00PM to 2:00PM
Location: 32-D507
Host: Polina Golland, CSAIL
Contact: Polina Golland, 6172538005, polina@csail.mit.edu
Relevant URL: Understanding the highly complex, spatially distributed and temporally
organized phenomena entailed by mental processes using functional MRI is
an important research problem in cognitive and clinical neuroscience.
Classically, the analysis of functional Magnetic Resonance Imaging (fMRI)
has focused either on the creation of static maps localizing the metabolic
fingerprints of neural processes or on studying their temporal evolution
in a few pre-selected regions in the human brain. However, cognition
recruits the entire brain and the underlying mental processes are
fundamentally spatio-temporal in nature. By neglecting either the temporal
dimension or the spatial entirety of brain function, such methods must
necessarily compromise on extracting and representing all the information
contained in the data. In this work, I present a new paradigm to
facilitate a multivariate spatio-temporal model that allows a
time-resolved exploration of mental processes as captured by fMRI. Using a
state-space formalism that models the brain transitioning through a
sequence of cognitive states as it solves a mental task, we are able to
study the spatial distribution of activity along with its temporal
structure. In addition to revealing the mental patterns of an individual
subject, such a generative model enables group-level inferences in terms
of information-theoretic properties such as complexity and mutual
information. Efficient algorithms for estimating the parameters,
state-sequence and the hemodynamic behavior of the brain have been
developed. This method was applied to a multi-subject fMRI study for
developmental disorders and for schizophrenia.
I shall show the kind of inferences possible with
this method in analyzing and differentiating the groups and the
neuro-scientific conclusions that it provides.
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