Investigating the effects of magnetic fields generated during Transcranial Magnetic Stimulation using computer and biological models
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Transcranial Magnetic Stimulation (TMS) is a non-invasive neuromodulation technique that is growing in acceptance by the medical community and the general public. TMS was approved by the U.S. Food and Drug Administration (FDA) for treating major depressive disorder (MDD) in 2008, certain types of migraine headaches in 2013, and obsessive compulsive disorder (OCD) in 2018. Researchers are also investigating how TMS can be used for enhancing the recovery of motor functions after a stroke as well as other debilitating illnesses. Investigating the biological mechanisms involved in the brain’s response to TMS is a growing area of study. Of the many challenges for researchers to overcome are the ethical and safety standards that prevent the testing of new TMS devices and protocols on human subjects. To overcome these, researchers have two types of models that are used to recreate the brain and its components for TMS research. Computer models are used to simulate the neurological system’s responses to the magnetic fields generated during TMS. They are used to simulate the effects of new coil designs and stimulation protocols on different types of head models (i.e. a healthy brain versus a brain damaged by head trauma). Biological models use cell lines developed from animals that recreate the aspects of cells in the human brain that are affected by TMS.The research presented in this thesis shows the experimental results using both types of models to investigate the underlying mechanisms of TMS. A computer model was used to investigate the effects of brain-scalp distance of healthy subjects on the response to a novel TMS coil design. Two types of biological models were used to investigate, at the cellular level, the effects of magnetic fields generated by a commercial TMS system on neuronal cells in vitro.