Yusoff, Bazli Md
(2021)
Analysis of brain activation and effective connectivity during self-paced unilateral and bilateral finger tapping using functional magnetic resonance imaging in patients with temporal lobe epilepsy.
Masters thesis, Universiti Sains Malaysia.
Abstract
Background: Temporal lobe is the most frequent site of origin of partial seizures. Patients with
Temporal Lobe Epilepsy (TLE) represent approximately two thirds of the intractable seizure
population.
Objectives: This study aims to compare the area of activation in between Healthy subjects and
Temporal Lobe Epilepsy (TLE) patients as a result of increase in blood oxygen level in
different parts of the brain during self-paced unilateral and bilateral finger tapping. In addition,
this study also aims to compare the effective connectivity in between region of interest in
Healthy subjects and TLE patients during self-paced unilateral and bilateral finger tapping.
Methodology: This study involves 12 healthy subjects and 12 TLE patients. All of them
undergone functional magnetic resonance imaging (fMRI) where they performed self-paced
unilateral and bilateral finger tapping. The images were then pre-processed and undergone first
level analysis using Statistical Parametric Mapping (SPM). Second level analysis were then
performed to compare the area of activation in Healthy subjects and TLE patients. For effective
connectivity, two regions of interest chosen which representing visual and motor region. Three
models tested in between each region of interest which are bidirectional, visual to motor and
motor to visual. These tests were conducted in each brain hemispheres of both Healthy subjects
and TLE patients.
Results: In both Healthy subjects and TLE patients, first level analysis showed intense
activation at the visual area. Second level analysis was performed comparing the two group of
samples, using two samples t-test, FWE p < 0.05, Healthy subjects showed more areas of
significant activation. For effective connectivity, two regions of interest were tested, visual
area and motor area. Three models were tested, bidirectional, visual to motor, and motor to visual. In healthy subjects, visual to motor was the dominant model with average value of
0.03Hz bilaterally. In TLE subjects, on the right hemisphere, a contrary result was observed
whereby motor to visual area was the dominant model. On the left hemisphere, the same model
as healthy subjects was the dominant model, visual to motor, but with higher average value of
0.1Hz.
Conclusion: This study found that there was less area of brain that has significant activation in
TLE patients during motor activity. TLE brains also exhibit different effective connectivity
whereby in the right hemisphere, motor area exerts more influence on the visual area and in
the left hemisphere, visual area exerts significantly more influence on the motor area. These
findings suggest that there is alteration of the motor networks in TLE patients.
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