MTOR and depressive symptom measurement: Specifically, using a rodent model of depression, Li et al. (2010) demonstrated that administration of the dissociative anesthetic ketamine, a glutamate N-methyl-D-aspartic acid receptor (NMDAR) antagonist, rapidly activated the mTOR pathway, leading to increased synaptic signaling and new spine synapses in the prefrontal cortex (PFC).