Effects of Transcranial Magnetic Stimulation on Parkinsonian Motor Neurons

Parkinson’s disease (PD) is a neurological condition which affects millions of people and can lead to fatal complications. Patients often receive deep brain stimulation (DBS), an invasive but effective treatment in which a probe is inserted into nuclei deep in the brain. This probe provides continuous current and the treatment has been shown to alleviate various symptoms of PD. Recent studies have also shown that it is possible to use transcranial magnetic stimulation (TMS) to alleviate parkinsonian symptoms by stimulating motor areas of the brain. While DBS and TMS are significant medical advancements, their exact cellular mechanisms are poorly understood. We explore the firing rates and patterns of motor pathway neurons using a novel computational model. We have developed healthy and PD motor pathway models with similar firing rates as those observed from in vivo studies. We then induce DBS-like current in the PD neurons and observe the consequent neuron firing patterns, and manipulate various parameters of TMS to observe the deep brain effects of cortical non-invasive TMS. Results indicate that it may be possible to emulate DBS firing using non-invasive cortical TMS if a pulse rate of 50 Hz can be achieved and any side effects such as overstimulation of tissue can be avoided.