Brain Connectivity changes after Stroke and Rehabilitation

This is bizarre that this dissertation is from the Department of Physics and Astronomy. Only 101 pages for your doctor to explain to you.
http://scholar.google.com/scholar_url?url=http://scholarworks.gsu.edu/cgi/viewcontent.cgi%3Farticle%3D1076%26context%3Dphy_astr_diss&hl=en&sa=X&scisig=AAGBfm2_KLX6CwXNpeOlOrTiIDYf70uUmQ&nossl=1&oi=scholaralrt
ABSTRACT
Several cortical and subcortical areas of brain interact coherently during various tasks such as
motor-imagery (MI) and motor-execution (ME) and even during resting-state (RS). How these
interactions are affected following stroke and how the functional organization is regained from
rehabilitative treatments as people begin to recover have not been systematically studied. Role
of primary motor area during MI task and how this differs during ME task are still questions of
interest.
To answer such questions, we recorded functional magnetic resonance imaging (fMRI) signals
from 30 participants: 17 young healthy controls and 13 aged stroke survivors following stroke and
following rehabilitation - either mental practice (MP) or combined session of mental practice
and physical therapy (MP + PT). All the participants performed RS task whereas stroke survivors
performed MI and ME tasks as well. We investigated the activity of motor network consisting of
the left primary motor area (LM1), the right primary motor area (RM1), the left pre-motor cortex
(LPMC), the right pre-motor cortex (RPMC) and the midline supplementary motor area (SMA).
In this dissertation, first, we report that during RS the causal information flow (i) between the
regions was reduced significantly following stroke (ii) did not increase significantly after MP
alone and (iii) among the regions after MP+PT increased significantly towards the causal flow
values for young able-bodied people. Second, we found that there was suppressive influence of
SMA on M1 during MI task where as the influence was unrestricted during ME task. We reported
that following intervention the connection between PMC and M1 was stronger during MI task
whereas along with connection from PMC to M1, SMA to M1 also dominated during ME task.
Behavioral results showed significant improvement in sensation and motor scores and
significant correlation between differences in Fugl-Meyer Assessment (FMA) scores and
differences in causal flow values as well differences in endogenous connectivity measures before
and after intervention. We conclude that the spectra of causal information flow can be used as a
reliable biomarker for evaluating rehabilitation in stroke survivors. These studies deepen our
understanding of motor network activity during the recovery of motor behaviors in stroke.
Understanding the stroke specific effective connectivity may be clinically beneficial in identifying
effective treatments to maximize functional recovery in stroke survivors.