RecruitingDevice studyrTMS to Improve Cognition in Parkinson'sThe purpose of this study is to examine safety, feasibility, and the behavioral and brain effects of a non-invasive treatment, repetitive transcranial magnetic stimulation (rTMS), for Veterans with Parkinson's disease or atypical parkinsonism and mild impairments in their thinking. The hypothesis is that rTMS can improve thinking for people with Parkinson's disease or atypical parkinsonism who are experiencing mild problems with their thinking ability.