A Study to Evaluate Sigma-1 and Dopamine-2 Receptor Occupancy by Pridopidine in the Human Brain of Healthy Volunteers and in Patients With Huntington's Disease

Inclusion Criteria: * In general, good physical health as determined by medical history and psychiatric history, suicidality assessment \& physical examination * Men who are potentially fertile (not surgically \[eg, vasectomy\] or congenitally sterile * Patients with Huntington's disease (HD): diagnosis of HD and with an onset of HD after 18 years of age * Additional criteria apply, please contact the investigator for more information Exclusion Criteria: * The subject has been previously exposed to ionizing radiation or radioactive substances as a result of clinical research or medical treatment in the past 10 years. * The subject has a counterindication to having an MRI * History of alcohol, narcotic, or any other substance dependence in the past 2 years * Additional Exclusion criteria to patients with Huntington's disease: * The patient has a severe motor impairment that might cause artifacts. * Patients with a known history of Long QT Syndrome or a first degree relative with this condition. * Treatment with any investigational product within 6 weeks of screening or patients planning to participate in another clinical study assessing any investigational product during the study. * Additional criteria apply, please contact the investigator for more information