Dementias and Alzheimer's disease pose a challenge for diagnosticians because, given the wide range of symptoms, it is easy to make an incorrect diagnosis. PET scans, or lumbar puncture scans, are used to obtain results that can be used to confirm or exclude the above-mentioned conditions. However, these tests are either costly or invasive and dangerous for the patient. As an alternative, a magnetic stimulation test may be used to image the conduction of electrical impulses in individual brain circuits.