This study investigates the interactions between NMDA (N-Methyl-D-aspartic acid) antagonism and GABA (gamma-aminobutyric acid) system as it relates to cognitive function assessed by ERPs (event-related potentials) in healthy volunteers.

Inclusion criteria:

• Ages of 21-45 years from all ethnic backgrounds.
• Male or female.
• Written informed consent.

Exclusion criteria:

• DSM-IV diagnosis for a psychotic, depressive or anxiety disorder.
• A history of significant medical/neurological disease such as cardiac, thyroid, renal, hepatic abnormality, seizure disorder. Unstable medical condition based on EKG, vital signs, physical examination and laboratory work-up (CBC with differential, SMA-7, LFTs, TFTs, UA, Utox).
• History of abnormal EEG.
• History of severe allergies or multiple adverse drug reactions.
• Any medication that could interfere with either the safety of the study and/or the outcome measures.
• Any other conditions which in the opinion of the investigator would preclude participation in the study.
• History of major psychiatric disorder in first degree relatives.
• Current substance abuse/dependency determined by urine toxicology.
• Treatment with medications with CNS effects.
• Treatment with benzodiazepines within one week prior to testing.
• Current treatment with medications with psychotropic effects.
• Education < 10th grade.
• IQ < 70, MR.
• Non-English speaking.