Changes only the fields present in the request body; omitted fields keep their current value. A field sent as null counts as omitted; send an empty string to clear description or notes. A body with no updatable field is rejected with 400. When present, name must not be blank. The study stays in its current project; a projectID in the body is ignored — use POST /api/v1/studies/{studyID}/move to move it. Collaborators, managers, and meta fields are not managed by this endpoint and are left unchanged. A name change is recorded in the study's journal log. Use the PUT call to replace the whole study.