This will be a double-blind (neither physician nor the volunteer knowns whether placebo or active drug is administered), placebo-controlled, randomized (study drug is assigned by chance), 2-way crossover (the same procedure is repeated twice so that the volunteer receives placebo as well as active drug) study in cohorts of a maximum of 16 healthy male volunteers each, to investigate the effect of JNJ 40411813 or placebo on ketamine-induced psychosis-like symptoms. In the first cohort (Cohort 1), JNJ 40411813 effects at a dose level of 500 mg will be evaluated at the time of maximal plasma concentrations. If JNJ 40411813 significantly reduces psychotic symptoms relative to placebo, a second cohort (Cohort 2) will be initiated to investigate the effects of JNJ 40411813 at 24 hours following dose administration. If Cohort 1 shows no relevant effects of JNJ 40411813 the study will be stopped. If there are no relevant effects of JNJ 40411813 on the psychotic symptoms at 24 hours after dosing, a third cohort (Cohort 3) will be initiated to investigate the effects at 12 hours after dosing. If there are relevant effects of JNJ 40411813 at 24 hours after dosing, a fourth cohort (Cohort 4) following the same procedures as Cohort 1, will be initiated to investigate the effects at peak plasma concentration using a lower dose of JNJ 40411813. Volunteers will be randomly assigned in a crossover procedure to one of two sequences (JNJ 40411813/placebo or placebo/ JNJ 40411813) on Day -1 of the first study period of each cohort. At peak plasma level (Cohorts 1 and 4), 24 hours (Cohort 2) or 12 hours (Cohort 3) after dosing volunteers will receive ketamine as an infusion (i.e. directly into the vein) over 60 minutes. The ketamine administration will be preceded by a saline infusion over 90 minutes. Tests on the psychological function of the volunteers will be performed during and after saline and ketamine infusion. Safety assessments include daily ECG and vital signs, clinical laboratory assessments at the start and end of each study period, pulse oximetry (measurement of the oxygen content of the blood ) during each ketamine infusion and continuous Adverse Event Reporting. The study will be double blind for oral JNJ-40411813 or placebo, but open label (everyone knows the identity) for the IV administration of saline and ketamine. JNJ-40411813: 500 mg single oral dose or lower or matching placebo. Ketamine: continuous intravenous infusion of 0.005 mg/kg/min over 60 minutes.