Figure 2.

Effects of site-specific depletion of basal forebrain cholinergic corticopetal inputs to early and late phases of skilled motor learning. Motor learning (rates of task acquisition) were analyzed across 2 distinct phases; an “early” phase (days 1–4) in which rapid improvements in reaching performance are typically observed, and a late phase (days 5–10) whereby more subtle refinements in performance occur. Rates of motor learning were calculated either by determining the slope of the acquisition performance curve (A,C), or by determining the absolute change in performance over the given analyzed period (B,D). Animals with cholinergic lesions targeting either PFC or AUD had no significant effect on early or late phases of learning relative to vehicle-treated controls (P > 0.7 for all post hoc comparisons). In contrast, rates of learning during the early phase of acquisition were significantly altered in animals with either selective motor depletions or global cholinergic lesions (A,B; **P < 0.005 in all cases). Animals subjected to selective cholinergic depletion of the motor cortex exhibited comparable deficits in the rate of learning during early phase acquisition relative to global cholinergic lesioned animals (post hoc Fisher's, P = 0.89 [for slope] and P = 0.96 [for absolute change in performance] comparing motor-lesioned and global-lesioned animals). Learning rates during late phase skilled motor acquisition did not differ across treatment groups (C,D, P = 0.68 overall ANOVA for “slope” and P = 0.91 overall ANOVA for absolute change in performance).