In this study, healthy participants will be randomized into one of two parallel groups: (a) open-label ketamine and active lamotrigine, or (b) open-label ketamine with a matched-placebo control (i.e., sugar pill). All participants will complete a baseline rs-fMRI approximately 1-week prior to the ketamine infusion and a follow-up rs-fMRI 24-hours post-infusion. The subanesthetic dose of ketamine (0.23mg/kg bolus followed by 0.58mg/kg infusion over approximately 60 minutes) will be administered via intravenous infusion to occur during the MRS scan. Participants will be administered lamotrigine (300 mg oral dose) or the matched-placebo control about 2-hours prior to the start of the infusion.