Histology and immunostaining Histological examination was done as described9. For the morphometric analysis, serial coronal sections were prepared, and analyzed at the following positions: +0.74 to +1.10 for the septum, diagonal band, striatum and the motor cortex; −0.34 to −0.82 for the substantia innominata, the basal nucleus of the Meynert, and the somatosensory cortex [anterior(+) to posterior(−) distance (mm) from bregma according to Paxinos et al.53]. The sections were stained with cresyl violet or by utilizing endogenous acetylcholine esterase activity54 for histological examination. Immunostaining was performed as previously described55. The primary antibodies were rabbit mouse anti-choline acetyltransferase (ChAT) polyclonal antibody (Chemicon, Temecula, CA, USA), mouse monoclonal anti-parvalbumin (PV) (Sigma, St. Louis, MO, USA), and rabbit anti-pan-Zic antibodies10.