What is proposed mechanism of dissociative anesthesia effect of ketamine:-

Ketamine produces dissociative anesthesia which is characterized by a state wherein the patient is conscious (eg., eye opening, swallowing, muscle contracture) but unable to process or respond to sensory input. It acts as an antagonist at the phencyclidine site of the NMDA receptor. Ketamine functionally "dissociates" the thalamus (which relays sensory impulses from the reticular activating system to the cerebral coex) from the limbic coex (which is involved with the awareness of sensation). Though the patient may have intact corneal, cough, and swallow reflexes, they need not be protective.