Differences in SYP staining was observed in the CA3 region of exposed mice (B) versus controls (A) at 5 months post exposure (Welch’s t-test = 12.7, DF = 1, p < 0.01). In addition, significantly reduced SYP staining was evident in the cerebral cortices of exposed mice (D), as compared to controls (C) (Welch’s t-test = 10.26, DF = 1, p = 0.03). Representative images were taken at 60X magnification (scale bars represent 1 mm). Inset depicts positive SYP staining showing dark brown pre-synaptic vesicles stained within the cell soma (see insets in A and C). Histograms depict the quantification of the SYP stain in the hippocampi, and cerebral cortices, as % Area per microscopic field, and error bars represent standard error of the mean (SEM).