Cerebellar Stimulation and Cognitive Control

Our recent work found that patients with Parkinson's disease and schizophrenia have impaired frontal EEG rhythms in the theta and delta range (1-8 Hz).We have been using transcranial direct current stimulation to recover these rhythms as patients perform elementary cognitive tasks. We found that although we are able to modulate cerebellar and frontal activity with tDCS, this effect is minimal as the depth of the current is not great enough to modulate all cerebellar activity. Here we use transcranial magnetic stimulation (TMS) to modulate neural activity in the frontal cortex and recover cognitive function in patients with autism, schizophrenia, bipolar disorder and Parkinson's disease. The purpose of the study is to explore cerebellar stimulation as a potential new treatment to restore frontal activity and cognitive function in autism, schizophrenia, bipolar disorder and Parkinson's disease.Subjects will be brought in for 5 to 6 separate visits, with cerebellar or sham TMS stimulation twice per day for 5 days, as well as 3 follow-up visits.During these visits the patient will have cognitive, disease-specific and emotional testing, including EEG testing and MRI imaging. For those participants that received sham stimulation we will again use EEG to record how single pulses of magnetic or electrical stimulation influences other regions of the cerebellum and downstream brain regions. These data will provide insight into how the cerebellum may influence downstream brain regions and play a role in cognitive and motor performance. All data will be analyzed offline to determine if performance on the interval timing task and/or frontal brain rhythms change following transcranial magnetic stimulation as compared to the pre-stimulation blocks of trials. Additionally, we will analyze changes in their cognitive function, symptom ratings, functional and structural MRI, and mood following stimulation. Controls will receive both active and sham treatment for comparison.