system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do hallucinogens (i.e. mushrooms) make it seem like inanimate objects are moving/breathing?
gpt
The hallucinations happen because the drug mimics a chemical messenger in the brain called serotonin. While serotonin is usually described as a "happiness" chemical - it also plays a number of other roles. The brain has at least 14 different receptors for serotonin, all of which play a different part in regulating functions such as our mood and how we interpret what our senses tell us. When a drug binds to the serotonin receptor instead of *actual* serotonin, the brain misinterprets it as another serotonin signal in combination with the signals it is receiving from other receptors, causing hallucinations.