THURSDAY, Sept. 16 (HealthDayNews) -- Some folks giggle. Others become paranoid.

Marijuana affects people in a variety of ways, and doctors believe they've zeroed in on how the drug influences human behavior.

Stanford University researchers found that a group of neurons that acts as information gatekeepers in the brain's major information processing center -- the cerebral cortex -- quiet their own activity by releasing a chemical that's the same as the active ingredient in marijuana.

The researchers believe marijuana may work its brain-altering effects by binding to these same cells.

"Marijuana is a major drug of abuse with actions in the brain that aren't entirely known," said lead researcher Dr. David Prince. "Now we understand one piece of the puzzle."

The findings appear in the Sept. 16 issue of Nature.

More information

The National Institute on Drug Abuse has more about marijuana.