(A) Target premature responses on the ITI8 challenge session (baseline impulsivity) predicted responsiveness to D-cycloserine (1, 2, 5, 10, 20, or 50 mg/kg i.p.; 15 min pretreatment) during the ITI5 maintenance sessions (p<0.05). Inherent motor impulsivity was not a predictive factor for (B) reinforcers earned (n.s.), (C) accuracy (n.s.), or (D) percent omissions (n.s.). The relationship between 1-CSRT task measures on an ITI8 challenge and ITI5 session for each pretreatment condition with vehicle or D-cycloserine is represented by a linear regression line.