The Cerebellum as a Potential Treatment Site for PD Motor Symptoms

The Contribution of the Cerebello-thalamo-cortical Circuit to the Pathology of Non-dopaminergic Responsive Parkinson's Disease Symptoms

The role of the cerebello-thalamo-cortical loop in the generation of tremor, gait impairments and postural instability has been made evident. The current study will use a Magstim Rapid 2 to deliver rTMS with the aim of modulating the activity in the vermal/paravermal region of the cerebellum, and consequently the cerebello-thalamo-cortical pathway. Analysis of the effects of an acute session of stimulation will be made to determine the therapeutic potential of the protocol. Motor symptom improvement will be assessed immediately following stimulation to detect motor symptom improvement up to one hour following stimulation, providing insight into the effectiveness of the protocol to produce benefits which outlast the period of stimulation. Participants will each receive one session of stimulation in the ON state of medication. A pre-assessment will be performed before beginning the session and a post-assessment will be performed immediately following stimulation. There will be two groups, which will both undergo the exact same protocol, however one group will receive real stimulation, and one group will receive sham stimulation.

Participants in this group will receive Repetitive Transcranial Magnetic Stimulation, characterized by 900 pulses at 1Hz over the medial cerebellum at 120% resting motor threshold of the right first dorsal interosseous.

Participants will receive Sham Repetitive Transcranial Magnetic Stimulation by having the coil angled at 90 degrees to the scalp; this will allow adequate noise output from the stimulator in the absence on real magnetic stimulation.

5 trials of self-paced gait on a GaitRite carpet using Zeno software to measure spatial and temporal aspects of gait.

3 trials lasting 30 seconds each of quiet stance on a balance force plate, where postural deviations from a central reference point on the platform will give an overall measure of postural sway, as well as score in the medial-lateral and anterior-posterior direction

Balance: Sensory Integration Testing (modified clinical test of sensory integration on balance (m-CTSIB)

In accordance with the modified clinical test of sensory integration on balance (m-CTSIB), where four trials lasting 20 seconds each measure balance during various sensory conditions: 1) eyes open, firm platform, 2) eyes closed, firm platform, 3) eyes open, foam platform, 4) eyes closed, foam platform.

Tremor: Kinesia Homeview Tablet (tremor magnitude, frequency and amplitude can be measured with wireless finger accelerometer)

With the use of a wireless finger accelerometer, tremor magnitude, frequency and amplitude can be measured during the upper limb movement tasks (such as rapid alternation and pointing tasks)

Inclusion Criteria: diagnosed with idiopathic Parkinson's disease ability to walk 10 metres unassisted ability to stand for 5 minutes unassisted understand verbal instructions in English Exclusion Criteria: presence of brain implants (aneurysm clips, deep brain stimulation electrodes) cochlear implants diagnosed with vascular Parkinson's disease history or increased risk of seizure severe dyskinesia of neck muscles