An animal study is shedding new light on the complicated chemistry of the brain, and how a drug intended to do one thing can have entirely unintended consequences.

Researchers at Georgetown University Medical Center set out to determine why some patients who take the sleep drug Ambien wind up on their feet, talking on the phone, even driving a car while not awake. The next day, they would have no recollection of what they had done.

To mimic the effect of Ambien (zolpidem), the scientists trimmed the whiskers of mice-depriving them of neural activity-and found that some inhibitory neurons their brains used to monitor neural activity were shut down. They concluded that Ambien was similarly shutting down neurons that play a key role in inhibiting other neural activity. Without the inhibitory neurons to monitor and control activity, people taking the drug experienced "awakenings."

"When brain activity is silenced, many neurons automatically react to this change. We see this in our study which suggests that inhibitory neurons responsible for stopping neural activity are themselves shut down by zolpidem," explains Molly M. Huntsman, an assistant professor in the department of pharmacology. "The excitatory neurons, responsible for transmitting activity, are then allowed to re-awaken and become active again, without monitoring because the inhibitory neurons are 'asleep'."

- check out the press release [1]