Psychedelic chemical subdues brain activity

24 01 2012

Magic mushrooms’ active ingredient constrains control centres.

Psilocybin, a compound found in magic mushrooms has long been valued for its ability to induce mystical experiences and potential to cure psychiatric conditions. The drug is known to activate serotonin receptors, but how this influences its effect is not known. Recently, David Nutt, a neuropsychopharmacologist at Imperial College London, and his colleagues, discovered that the hallucinogenic chemicals found in magic mushrooms do not have the potential to cure psychiatric conditions, but instead, they may induce widespread diseases in the brain.

David Nutt and his colleagues used functional magnetic resonance imaging (fMRI) to monitor the changes in brain activity during the transition from normal consciousness to the psychedelic state prompted by psciloybin. The researchers conducted a research with 30 participants who were all experienced users of hallucinogenic drugs. Throughout the experiment, the participants’ brains were scanned twice: once after the participants had been given a salt- water placebo and once after the injection of a moderate doe of psilocybin. Nutt says, “Psychedelics are thought of as ‘mind-expanding’ drugs, so it has commonly been assumed that they work by increasing brain activity. Surprisingly, we found that psilocybin actually caused activity to decrease in areas that have the densest connections with other areas.”

Most decreases were observed in the medial prefrontal cortex and the anterior and posterior cingulate cortices (ACC and PCC, respectively). The scans also showed a reduction in functional connectivity between the mPFC and PCC, so their normally synchronous activity was de- synchronized. In addition, the intensity of the drug’s effects, as reported by the participants, led to decreased ACC and mPFC activity levels. The mPFC, PCC and thalamus are ‘connector hubs’ that have a pivotal role in coordinating the flow of information through the brain and researchers state that this accounts for the effects of hallucinogens which are responsible for a state of  “unconstrained recognition”.

Nutt and his colleagues propose their results could explain the therapeutic effects of psilocybin. Depression involved hyperactivity in the mPFC which leads to a pessimistic outlook and pathological brooding characteristic of the condition. Thus, mPFC deactivation could ease those symptoms. The researchers also noticed reduced blood flow to the hypothalamus and suggested that this illuminates that psychedelics ease symptoms of cluster headaches which is related to increased hypothalamic activity.

However, Nutt and his colleagues’ findings conflict with other studies that have been done.

“We have completed a number of similar studies and we always saw an activation of these same areas,” says Franz Vollenweider at the University of Zurich in Switzerland. “We gave the drug orally and waited an hour, but they administered it intravenously just before the scans, so one explanation is that the effects were not that strong.”

And according to Keith Laws, a neuropsychologist at the University of Hertfordshire, UK, the results could be explained in another way. “Deactivation of the mPFC and PCC are linked to anxiety and anticipation of pleasant and unpleasant experiences,” he states. “This is a stressful situation, even for experienced drug users, and I suspect that they measured something to do with anxiety.”

 





The search for Planets

15 01 2012

Planets outside our solar system have been eluding scientists for years; twenty years ago, many scientists did not believe that there were many other planets, or at least that it would be impossible to see them, and record the makeup of their atmosphere. Now, over 700 planets have been found and recorded; Read the rest of this entry »