Figure 2.

Quantification of cholinergic innervation densities. Cholinergic axon density was determined in multiple cortical regions. Quantified regions included: inferior temporal cortex layers II (IT-II) and V (IT-V); insular cortex layers II (INS-II) and V (INS-V); cingulate cortex layer II (CING); frontal cortex layer II (FR); and hippocampal formation, stratum radiatum of CA1 (HF). Axon densities were determined by superimposing a 6 × 6 grid over a highly magnified image captured from one of the defined regions (see Inset). All AChE-stained fibers crossing the gridlines (arrows in Inset) were counted to yield an index of innervation density, as described by Guela and Mesulam (32). (Scale bar = 5 mm.) (Scale bar in Inset = 35 μm.)