Stanford Regulating Circuits of the Brain Study- Ketamine

Inclusion Criteria:

* Ages 18-55 years
* At least 2 prior uses of ketamine when aged 18+
* BMI within healthy range (18-30)
* Ability to speak, read, or understand English

Exclusion Criteria:

* Current active suicide ideation or history of suicide attempts
* Current mood, anxiety, eating, psychotic, or substance use disorder
* Lifetime psychotic or bipolar disorder
* Schizophrenia in a first degree relative
* Current use of psychotropic medication
* Prior adverse ketamine response
* Allergy or hypersensitivity to ketamine
* Use of ketamine in past 7 days
* Cannabis use in the past 7 days, illicit recreational drug use in the 48 hours prior to sessions, and/or alcohol use in the 24 hours prior to sessions
* Concurrent use of any medications that might increase the risk of participation (e.g., drug interactions)
* History of epilepsy, convulsions, seizures, LOC \>10 min
* Renal/hepatic impairment
* Hypertension (Stage 1 defined as systolic blood pressure \>140 mmHg or diastolic blood pressure \>90 mmHg on 2 of 3 measurements at least 15 min apart at initial screening; systolic blood pressure \>155 mmHg or diastolic blood pressure \>99 mmHg on 2 of 3 measurements at least 15 min apart during infusion visits)
* Heart rate \<50 bpm or \>150 bpm at initial screening
* Chronic congestive heart failure, tachyarrhythmias, myocardial ischemia assessed via EKG at initial screening
* EKG QTcF intervals \>430 ms for men and \>470 ms for women
* Direct physical access to or routine handling of addicting drugs in the regular course of work duties
* MRI contraindication
* Pregnant or nursing females