Dissociable effects of focal inhibition and excitation of primary motor cortex on functional connectivity within the motor network

Hearne, Luke (2012). Dissociable effects of focal inhibition and excitation of primary motor cortex on functional connectivity within the motor network Honours Thesis, School of Psychology, The University of Queensland.

       
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Author Hearne, Luke
Thesis Title Dissociable effects of focal inhibition and excitation of primary motor cortex on functional connectivity within the motor network
School, Centre or Institute School of Psychology
Institution The University of Queensland
Publication date 2012-10-10
Thesis type Honours Thesis
Supervisor Jason Mattingley
Total pages 86
Language eng
Subjects 1701 Psychology
Abstract/Summary The excitability of the human motor cortex can be altered by various forms of non-invasive brain stimulation. However, the influence that these local changes in cortical excitability have on functional connectivity among remote (but functionally related) brain regions is poorly understood. To this end, the current study used excitatory and inhibitory transcranial magnetic stimulation (TMS) to induce temporary changes in motor cortex excitability, and evaluated the effect of this change in cortical excitability on functional brain connectivity at rest using functional magnetic resonance imaging (fMRI). The efficiency of the TMS modulation was assessed by measuring muscle evoked potentials in the hand (the cortical region of which was targeted with TMS) before and after TMS. Imaging results indicated defined changes in intraand inter-regional functional connectivity throughout the sensory-motor network. The direction of changes in functional connectivity were related to the type of stimulation used, such that inhibitory stimulation decreased functional connectivity and excitatory stimulation increased functional connectivity. Results also suggested that highly interconnected neural hubs in the posterior midline of the brain extended changes in functional connectivity outside the sensory-motor network. Taken together, these findings demonstrate that local changes in cortical activity affect connectivity in large-scale brain networks. This conclusion has wide ranging implications, from the conceptualisation of human neuroplasticity to the application of TMS in clinical neuro-rehabilitation.
Keyword Focal inhibition and excitation
Primary motor cortex
Functional connectivity

 
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Created: Thu, 28 Feb 2013, 14:27:58 EST by Mrs Ann Lee on behalf of School of Psychology