The Effect of Functional Magnetic Resonance Imaging Connectivity on
Resting Motor Threshold Transcranial Magnetic Stimulation in
Schizophrenia Participants
Abstract
Schizophrenia is a neurological disorder known to influence the motor
region. Transcranial magnetic stimulation (TMS) is a non-invasive
neuromodulation technique being investigated as a treatment for
schizophrenia. Resting motor threshold (RMT) is the dosage parameter for
TMS treatment protocols and is known to vary between participants with
limited understanding of the drivers of this variance. Previous
investigations have used functional magnetic resonance imaging (MRI),
diffusion tensor imaging (DTI), and individual level neuroanatomy to
explain RMT variability. Our previous investigation showed neuroanatomy
influences RMT in both schizophrenia and healthy populations and this
relationship was weakened by the presence of schizophrenia. In this
study, 54 participants with schizophrenia-diagnosed, who were
antipsychotic naive and 43 non-impaired controls underwent single pulse
TMS, structural magnetic resonance imaging, and fMRI. An independent
component analysis (ICA) was used to process fMRI data into 25 distinct
channels where correlations were derived between channels. Linear and
multiple regression models were used to evaluate first, the influence of
these channel interactions on RMT followed by their influence when
individual level neuroanatomy was also considered. We found that
between-channel functional connectivity was altered in individuals with
schizophrenia and that fMRI can contribute to prediction of RMT, but
differently in both cohorts and to a lesser degree than individual level
neuroanatomical measures. This suggests that functional connectivity
influences TMS response and fMRI might help in dosage calculations of
clinical TMS protocols.