P4‐227: High Densities of Activated Microglia are Present in Cortical White Matter and Correspond to Regions of Greatest Atrophy in Primary Progressive Aphasia. (1st July 2016) - Ohm, Daniel T.; Kim, Garam; Gefen, Tamar; Parton, Zach; Bigio, Eileen H.; Rogalski, Emily J.; Mesulam, M. Marsel; Geula, Changiz