Figure 5.

Neural state-space structure is enhanced across expansion orders after a low dose of AMPH but destroyed after a high dose. A1, A2, SEs (mean ± SEM) as function of expansion order O for the 1.0 mg/kg (A1) and 3.3 mg/kg (A2) AMPH-treated animals for both the original data and corresponding bootstraps (gray squares). The same analyses for Wilk's lambda (B1, B2) and mean Mahalonobis distance (C1, C2). Note the clear local minimum in the 1.0 mg/kg AMPH condition compared with the weak minimum in the 3.3 mg/kg AMPH condition. For related analysis, see Movies 1–4. D1, Q^th-order correlations among neurons are diminished after 3.3 mg/kg AMPH relative to a SAL (**p < 0.01, rank-sum test). D2, Q^th-order correlations are decreased in animals that make at least three behavioral errors regardless of treatment group (**p < 0.01, rank-sum test).