ON WITH LAM: Derek Lam has designed a limited edition T-shirt for Brain Injury Awareness Month, which officially starts Thursday. To highlight the importance of helmet laws and concussion prevention, the designer sketched an artistic take on a brain and a helmet. All proceeds will benefit programs and services run by Opportunity Project, which helps people with brain injuries. The Milburn, N.J.-based nonprofit is selling 250 units of the $30 item through its Web site during the month of March. The Brain Injury Association of America and the Brain Injury Association of New Jersey also collaborated on the project.