Inclusion Criteria:  Healthy male and female subjects 21-40 years of age, inclusive at Visit 1 (Screening). Female subjects with a negative serum pregnancy test prior to entry into the study and who are practicing an adequate method of birth control (e.g., oral or parenteral contraceptives, intrauterine device, barrier, abstinence) and who do not plan to become pregnant during the study and for 30 days after the last dose of ketamine. Ability to understand the requirements of the study, provide written informed consent, abide by the study restrictions, and agree to return for the required assessments. Subject is judged to be in good health as determined by the investigator. Body mass index (BMI ) between 18.5 and 30.0 (inclusive) at Visit 1 (Screening). Ability to detect a 1000 and 2000 Hz tone at 40 dB in both ears, at Visit 1 (Screening). Ability to tolerate the electrode cap for the duration of the testing session.  Exclusion Criteria:  Clinically significant alcohol or other substance abuse within the last 1 year, in the opinion of the investigator; or unable to abstain from alcoholic beverages during the course of the study. Positive alcohol/drug screen for drugs of abuse (with the exception of a positive result considered by the investigator to be directly attributable to prescription medication approved for subject use) such as phencyclidine, benzodiazepines, opiates, cocaine, cannabinoids, amphetamines, and cotinine at any Visit. Excessive caffeine use (defined as habitual consumption of > 400 mg caffeine per day [~ four 8 oz. cups brewed caffeinated coffee or tea, ~ ten 12 oz. cans caffeinated soda or ~ two "energy shot" drinks]), or unable to abstain from caffeine on Visits 2-4. Use of products containing nicotine (tobacco or vaping products) 60 minutes prior to dosing on Visits 2-4. Current or prior history (defined as in the past 6 months) of treatment with N-methyl-D-aspartate receptor (NMDAR) ligands including ketamine, amantadine, dextromethorphan, memantine, methadone, dextropropoxyphene, or ketobemidone. History of allergy, sensitivity, or intolerance to NMDAR ligands including ketamine, amantadine, dextromethorphan, memantine, methadone, dextropropoxyphene, or ketobemidone. Any impairment, activity, or situation that in the judgment of the investigator would prevent satisfactory completion of the study protocol. History of significant psychiatric, neurologic (e.g. Huntington's, Parkinson's, Alzheimer's, Multiple Sclerosis, Type I or Type II diabetes mellitus, or a history of seizures, epilepsy, or strokes), or cognitive disorders (e.g. bipolar, schizophrenia, psychosis), or current (within 12 months prior to screening) psychiatric or cognitive disorders such as major depression, suicidal ideation, dementia, or anxiety disorders). Abnormal medical history, or concurrent conditions that, in the opinion of the investigator or sponsor designated medical monitor, would preclude safe study participation, or interfere with study procedures/assessments. History of severe renal or hepatic impairment, in the opinion of the investigator or the sponsor medical monitor. Known history of significant cardiovascular condition such as myocardial infarction, congestive heart failure, clinically significant arrhythmias, current uncontrolled cardiac arrhythmias, angina, acute ischemia. Hypertension characterized by resting systolic blood pressure > 140 mmHg or resting diastolic > 90 mmHg or tachycardia defined as a resting HR ≥ 120 bpm or bradycardia defined as a resting HR of ≤ 50 bpm, at any Visit. Hypotension with an abnormal supine blood pressure defined as SBP < 90 mmHg or DBP <60 mmHg at any Visit. Orthostatic hypotension consisting of a SBP change of ≥ 30 mmHg or a DBP change of ≥ 20 mmHg at 3 minutes after standing from a supine position at any Visit. Resting heart rate < 45 or > 95 beats per minute. A marked baseline prolongation of QT/QTc interval (such as QTc intervals that are repeatedly greater than 450 ms) or any other relevant ECG finding at Visit 1 (Screening). A history of additional risk factors for Torsade de Pointes (such as heart failure, hypokalaemia, or family history of Long QT Syndrome). Current evidence of dysplasia or history of malignancy (including lymphoma and leukemia) in the last 5 years, with the exception of successfully treated non-metastatic basal cell or squamous cell carcinoma of the skin or localized carcinoma in situ of the cervix. Human immunodeficiency virus (HIV) infection, hepatitis, or other ongoing infectious disease that the investigator considers clinically significant. History of gastrointestinal disease or surgery (except simple appendectomy or hernia repair), which can influence the absorption of the study drug. Evidence of an infection at the time of clinic admission, in the opinion of the investigator. Received an investigational product or device within 30 days (or 5 half-lives, whichever is longer) of dosing. Use of first generation, sedating H1 antihistamines or sedative-hypnotic medications within 1 week prior to dosing. Poor venous access; or have donated or had a significant loss of blood or plasma within 8 weeks of dosing. Known allergy to latex. Prior adverse reaction to ketamine or esketamine. Medical history, conditions, or situations that, in the opinion of the investigator, would preclude safe study participation, or interfere with study procedures/assessments. In addition to these criteria, the investigator may discontinue subjects at any time based on his or her clinical judgment.