MTOR and depressive symptom measurement: Possibly the combination of ketamine with additional agents [e.g., the mTORC1 inhibitor rapamycin, which on its own has memory-improving effects (Richardson et al., 2015)] would have protective or synergistic effects.On the other hand, one study of a chronic social defeat model of depression found that mTOR plays a role in the antidepressant effects of (S)-ketamine, but not the enantiomer (R)-ketamine, whereas ERK plays a role in (R)-ketamine's antidepressant effects (Yang et al., 2018b).