Basal forebrain pathology in ALS including TDP-43 immunostain examples from six different ALS patients. (A) Representative low-power histologic section (LFB/PAS-hematoxylin) demonstrating magnocellular neurons within nucleus of the diagnonal band (NDB) (pial surface at bottom left of image). (B) Skein-like TDP-43 inclusion within the horizontal limb of the NDB (400 ×, scale bar is 20 microns). (C) Representative lower-power histologic section demonstrating the location of the bed nucleus of the stria terminalis (BNST) and adjacent lateral septal area (LSA) at the level of the internal capsule (ic), anterior commissure (ac), and lateral ventricle (lv) (compare to Figure 1A). (D) Numerous NCIs within the BNST (highlighted by black arrows) (200 ×, scale bar is 50 microns). (E) Low-power LFB/PAS-H histologic section demonstrating ventral striatum (Vs/Is) including clusters or “islands” of small neurons (bottom center of image). (F) Numerous NCIs in small neurons of the VS/Is (400 ×). (G,H) Medium-sized neurons of “substantia innominata” with frequent TDP-43 NCIs and neurities (bottom left of H). These cells could not be attributed to a specific nuclear group or region on H&E stain (see text) (400 ×) (H, inset). A glial cytoplasmic inclusion (at 400 ×) is shown for comparison of cell size with small- and medium-sized neurons with NCIs in panels D, F, G, and H.