what happens to Kesey on the drug trip?

LSD also has dramatic effects on the senses. Colors, smells, sounds, and other sensations seem highly intensified. In some cases, sensory perceptions may blend in a phenomenon known as synesthesia, in which a person seems to hear or feel colors and see sounds.

Hallucinations distort or transform shapes and movements, and they may give rise to a perception that time is moving very slowly or that the user's body is changing shape. On some trips, users experience sensations that are enjoyable and mentally stimulating and that produce a sense of heightened understanding.

The precise mechanism by which LSD alters perceptions is still unclear. Evidence from laboratory studies suggests that LSD, like hallucinogenic plants, acts on certain groups of serotonin receptors designated the 5-HT2 receptors, and that its effects are most prominent in two brain regions: One is the cerebral cortex, an area involved in mood, cognition, and perception; the other is the locus ceruleus, which receives sensory signals from all areas of the body and has been described as the brain's "novelty detector" for important external stimuli.

LSD's effects typically begin within 30 to 90 minutes of ingestion and may last as long as 12 hours. Users refer to LSD and other hallucinogenic experiences as "trips" and to the acute adverse experiences as "bad trips."