A Study to Investigate JNJ-40411813 in Combination With Levetiracetam or Brivaracetam in Epilepsy

Inclusion Criteria: * Body mass index (BMI) between 18 and 35 kilogram per meter square (kg/m\^2, inclusive (BMI = weight/height\^2). Minimum body weight should be 40-kilogram (kg) * Established diagnosis of focal epilepsy, for at least 1 year using the International League Against Epilepsy (ILAE) criteria. Participants should not be enrolled if they are known to have had fewer than 3 or more than 100 seizures in any monthly period in the past 6 months. It is preferred that participants have experience in maintaining a seizure e-diary * Must have had a neuroimaging procedure within 10 years, including a computed tomography (CT) scan or magnetic resonance imaging (MRI), that excluded a progressive neurologic disorder; these procedures may be performed within the 8-week baseline period * Cohort 1: Current treatment with at least 1 and up to 4 anti-epileptic drugs (AEDs) (including levetiracetam), administered at stable dosage(s) for at least 1 month before screening, and no new AEDs added for the previous 2 months; these AEDs must remain unchanged throughout the pretreatment and double-blind treatment periods (with the exception of dosage reductions of concomitant AEDs because of suspected elevated AED levels or side effects) Cohort 2 and beyond: Current treatment with at least 1 and up to 4 AEDs (including levetiracetam or brivaracetam), administered at the appropriate dosage(s) and for a sufficient treatment period before screening. These AEDs must remain unchanged throughou…