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Psilocybin cuts brain blood flow and connections

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  1. Terrapinzflyer
    Psychedelic drug users throughout the ages have described their experiences as mind-expanding. They might be surprised, therefore, to hear that psilocybin – the active ingredient in magic mushrooms – actually decreases blood flow as well as connectivity between important areas of the brain that control perception and cognition.

    The same areas can be overactive in people who suffer from depression, making the drug a potential treatment option for the condition.

    The study is the first time that psilocybin's effects have been measured with fMRI, and the first experiment involving a hallucinogenic drug and human participants in the UK for decades.

    Robin Carhart-Harris at Imperial College London and colleagues recruited 30 volunteers who agreed to be injected with psilocybin and have their brain scanned using two types of fMRI.

    Half of the volunteers had their blood flow measured during the resulting trip; the rest underwent a scan that measured connectivity between different regions of the brain.

    Low flow

    Less blood flow was seen in the brain regions known as the thalamus, the posterior cingulate and the medial prefrontal cortex. "Seeing a decrease was surprising. We thought profound experience equalled more activity, but this formula is clearly too simplistic," says Carhart-Harris. "We didn't see an increase in any regions," he says.

    Decreases in connectivity were also observed, such as between the hippocampus and the posterior cingulate and medial prefrontal cortex.

    "Under psilocybin you see a relative decrease in 'talk' between the hippocampus and these cortical hub regions," says Carhart-Harris. "Changes in function in the posterior cingulate in particular are associated with changes in consciousness."

    Mood swing

    Psilocybin has a similar chemical structure to serotonin – a hormone involved in regulating mood – and therefore binds to serotonin receptors on nerve cells in the brain. The drug may have therapeutic potential because the serotonin system in nerves is also a target for existing antidepressants.

    A study earlier this year by Charles Grob at the University of California, Los Angeles, showed that people with end-stage cancer had significantly less anxiety and better mood after receiving psilocybin in archives here.

    Franz Vollenweider, who works in a similar field at the Psychiatric University Hospital Zurich, Switzerland, says that the immediate effects of psilocybin are not as important for clinical benefit as the longer-term effects. That's because psilocybin increases the expression of genes and signalling proteins associated with nerve growth and connectivity, he says: "We think that the antidepressant effects of psilocybin may be due to a possible increase of factors that activate long-term neuroplasticity."

    Carhart-Harris presented his work at the Breaking Convention conference at the University of Kent in Canterbury, UK, this week


    08 April 2011 by Arran Frood
    http://www.newscientist.com/article...ug-cuts-brain-blood-flow-and-connections.html

Comments

  1. NeuroChi
    What is a "mock-fMRI environment" ? Other posts online say this device doesn't generate any images at all, and that its made of wood. Not that that discredits the results, just something I'd like more info on.

    Carhart-Harris RL, Williams TM, Sessa B, Tyacke R, Feilding A, Nutt DJ (2010) The administration of psilocybin to healthy hallucinogen-experienced volunteers in a mock-fMRI environment: a preliminary investigation of tolerability.

  2. Terrapinzflyer
    maybe see this file in the archives: Robin Carhart-Harris- Using fMRI to investigate the effects of psilocybin on brain activation and blood flow . This is from a year ago so is presumably the earlier stages of the work that he gave the talk on at the UK conference this week. He has also done some fascinating work with DMT along the same lines. I need to go back and look at my notes from theMAPS conference- he had some really interesting data related to dosages...

    Robin is closely affiliated with The Beckley Foundation and David Nutt as well. I saw him speak at the MAPS conference. He is doing some mindblowing work...He is certainly among the top in his field. He has quite a few papers in the archives here (and undoubtedly more out there we *should* have if anyone with access wants to go searching), and he is also referenced a few times here in the forums.
  3. Heretic.Ape.
    I find the proposition of increased neuroplasticity intriguing. Though I'm not surprised at weakened connections between the thalamus and cortical areas considering the characteristic oddity of sensory processing. Also the teams assumption that more brain activity would lead to more profound states seems odd to me. Most profound states have been shown to be accompanied by very calm brainstates wherein most activity is found in very specific areas.
    On the other hand, an epileptic seizure (which I can tell you first hand is not so profound) involves, as the neurologist who took eeg's of my fits says "looks like your whole brain went off like a fireworks display.
    Interesting article. I'll need to brush off my neurology books from school to remind myself of the specifics of the other areas involved.
  4. Seaquake
    Presumably the mock-fmri was to check that the users didn't freak out in a real MRI machine as they can be quite claustrophobic.

    there was a bbc thing on the Brain which was in essence about mind control but the guy doing it also up meeting Prof Nutt and getting himself MRIed while under the influence of Psilocybin.
  5. Ghetto_Chem
    One thing too about psychedelics and medical enviroments...

    As Rick Strassman says a few times in his book DMT; The Spirit Molecule. A medical enviroment is a hard place to conduct a psychedelic experience. No matter how hard the doctors try to make everything "comfortable" there still is going to be different results from the typical experience.

    Not that the results here are incorrect, just that results may vary from one setting to the next. As setting is always toted as one of the most important aspects of the journey.

    Its hard to hear what God is saying when theres an anal probe up the ass to monitor temperature, blood pressure machine beeping, IV sticking out of the arm, and a doctor just sitting there staring at you. Haha

    With all that said, good article. This basically goes against everything every psychonaut ever thought, its not a mind expansion... More a mind implosion.

    Peace
  6. Roads
    So could we now consider the possibility that the hallucinatory and mind altering effects of Psilocybin, as well as the effects of similar drugs like LSD and DMT are not only mediated via Serotonin receptors, but by a simple reduction in blood flow to various parts of the brain - thus creating the distortions and disconnections where they normally wouldn't be?

    This could help explain Near-death experiences, and "Spiritual" experiences that some people have; as merely a side effect of blood being diverted from the brain.

    The panda would love to give his Christian zealot grandmother a call and make fun of her alleged "communications with God" as simply a lack of blood flow to her brain.

    Haha. This is great.
  7. Seaquake
  8. Alfa
    While that is a possibility worth considering, it would be jumping the gun to conclude that this is the case.
  9. Seaquake
    It's not outside the science to suggest near death experiences are down to cerebral hypoxia, and that is certainly one the explanations given for it. though it's not the only explanation, and unless someone undergoes MRI while having an NDE it's unlikely to ever be resolved. it'd be exceptionally unethical to essentially kill someone to find out what happens as a result of that.
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