Heat maps demonstrating microglial representation in prefrontal cortex, Bregma +2.5 mm. Absolute cell counts of microglia yielded x-y coordinates for each cell. (A) Coordinates were converted into representative heat maps for the region, which was divided into a 3 ± 5 grid for analysis of population differences. The point (0, 0) represents the most ventral point on the pial surface of the prefrontal cortex. Red indicates relatively heavily populated regions while blue indicates relatively lightly populated regions. (B) Two-dimensional representation of microglial population.