Table 1.

Monkeys' WM condition on behavioral test before killing

Animal groups and their treatments	WM status^{^a}
Amphetamine young animal group
Vehicle control	Normal
Amphetamine treatment	Deficit
Amphetamine-treated animals 6 mo after withdrawal	Recuperated to normal
Haloperidol young animal group
Vehicle control	Normal
Haloperidol treatment	Deficit
Haloperdol-treated animals after D₁ agonist administration	Recuperated to normal
Haloperidol aged animal group
Vehicle control	Normal
Haloperidol treatment	Deficit

↵^aThe WM status was determined by the results of animal performance on spatial delayed response shown in Figure 1A. Animals with significant reduction in the percentage of correct choices were considered to be WM deficient.