Tranquillisers increase your brain's stiffness

Results of a recent study by Swinburne University of Technology researchers may have resolved the long standing question of how tranquillisers affect brain waves. This work is expected to result in the development of new methods for monitoring the effects of drugs on the brain.

It is well known that benzodiazepines like Valium, Halcion or Xanax increase the frequency of brain waves, however until now the basis for this effect and its significance for cognition have remained unexplained. The Swinburne researchers have for the first time established theoretically, and verified experimentally, an important mechanism linking the site of benzodiazepine drug action in the nervous system to the subsequent changes in the brain's activity.

The research team, led by Dr David Liley, gave Xanax to a group of healthy male subjects and measured its effect on the brain's resting electrical activity. By analysing this recorded electrical activity using a sophisticated new method based on a mathematical theory of brain waves developed by Liley, the researchers were able to establish that the increase in the frequency of brain waves seen with benzodiazepine administration was associated with a reduction in the brains responsiveness.

If the electrical oscillations of the brain can be imagined as being like the oscillations of a spring, then the effect of benzodiazepines may be understood as causing this spring to become stiffer. The stiffer the spring is then the less likely it will respond to attempts at compressing it or extending it. In a similar manner external or internal brain stimuli induce less of a behavioural response, and it is this responsiveness that in general will correlate with benzodiazepine effect.

"This is an extremely important result," says Liley "in that it offers a plausible explanation for how benzodiazepines affect cognition and in doing so challenges the widely held belief that the higher the frequency the more active the brain is."

Item provided courtesy of Swinburne University of Technology