Pubdate: Sat, 25 Feb 2006
Source: Guardian, The (UK)
Copyright: 2006 Guardian Newspapers Limited
Contact:  http://www.guardian.co.uk/guardian/
Details: http://www.mapinc.org/media/175
Author: Ian Sample
Bookmark: http://www.mapinc.org/hallucinogens.htm (Hallucinogens)

WHY DOES LSD MAKE YOU HALLUCINATE?

The Secret Intelligence Service, MI6, has paid thousands of pounds in 
compensation to servicemen after feeding them LSD in mind control 
experiments in the 1950s, it emerged this week.

One of the men involved in the clandestine tests received the drug 
twice a week, and recalls lengthy hallucinations in which walls 
melted, cracks appeared in people's faces and eyes ran down cheeks.

The hallucinations happen because the drug mimics a chemical 
messenger in the brain called serotonin. While serotonin is usually 
described as a "feelgood" chemical - it is the neurotransmitter 
released by the drug ecstasy - 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.

"We think serotonin helps keep a handle on perception and actually 
stops us from hallucinating," says Clare Stanford, a 
psychopharmacologist at University College London.

A dose of LSD, or lysergic acid diethylamide, targets a specific 
serotonin receptor called 5-HT2A, and in doing so appears to throw 
our senses into a jumble. As a result, images we would never normally 
perceive become vivid and fool our brains into thinking they are real.

"The drug can also cause synaesthesia, a condition which happens 
naturally in a small percentage of the population, where your senses 
get mixed up and you start smelling colours and tasting sounds," says 
Dr Stanford.

The MI6 experiments were carried out between 1953 and 1954 by 
scientists intent on developing a "truth drug" to extract confessions 
from prisoners.

The CIA tested LSD for the same purpose, but both agencies eventually 
ditched the studies after concluding the drug could not be used to 
manipulate people.
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