A Study to Assess the Electrophysiology, Safety, Tolerability, Pharmacokinetics and Pharmacodynamics Response Using Magnetic Resonance Imaging of SAGE-718 Using a Ketamine Challenge in Healthy Subjects

Inclusion Criteria:

1. Subject is willing and able to provide 2 forms of identification; at least 1 must have
a photo.

2. Subject has a body weight ≥50 kg and body mass index ≥18.0 and ≤30.0 kg/m2 at
screening.

3. Subject is healthy with no history or evidence of clinically relevant medical
disorders as determined by the Investigator.

Exclusion Criteria:

1. Subject has a history or presence of any psychiatric disease or condition including
suicidal ideation or behavior, has answered YES to any question on the C-SSRS at
screening or admission, or is currently at risk of suicide in the opinion of the
Investigator

2. Subject has a history or presence of a neurologic disease or condition, including but
not limited to epilepsy, closed head trauma with clinically significant sequelae, or a
prior seizure.

3. Subject has a family history of epilepsy.

4. Subject has evidence of any metal in the body that may be contraindicated for
receiving an MRI. This includes, but is not limited to: cardiac pacemaker, surgical
implants, previous accident resulting in metal or shrapnel lodged internally, tattoos
inked with metallic dyes, or a history of metal work without using protective eyewear.

5. Subject has claustrophobia or a history of claustrophobia.

6. Subject is unable or unwilling to remove piercings and/or jewelry that contain metal.