Provocative findings on the effects of ayahuasca in the brain

Under the somewhat misleading title Drug hallucinations look real in the brain, science writer Arran Frood  reported  in the New Scientist on a study using the functional MRI brain scanning technique  to look at the brains of users of ayahuasca.  The researchers compared the brain scans of volunteers under three conditions: (1) looking at pictures of people or animals; (2) imagining and remembering looking at those images; (3) imagining and remembering the image while on ayahuasca. Here’s what the report says of the comparison between conditions (1) and (2):

Draulio de Araujo of the Brain Institute at the Federal University of Rio Grande do Norte in Natal, Brazil, and colleagues recruited 10 frequent users of the brew – called ayahuasca. They asked the volunteers to look at images of people or animals while their brains were scanned using functional MRI, then asked the volunteers to close their eyes and imagine they were still viewing the image. Unsurprisingly, the researchers found that neural activity in the primary visual cortex dropped off when volunteers imagined seeing the image rather than actually viewing it.

And here’s what the findings were comparing conditions (1) and (3) – the brain scans registered equally strong activity in the visual cortex, a finding that is indicative of the  amplifying effect of entheogens.

But when the team then gave the volunteers a dose of ayahuasca and repeated the experiment, they found that the level of activity in the primary visual cortex was virtually indistinguishable when the volunteers were really viewing an image and when they were imagining it.

According to the researchers – “This means visions seen have a real, neurological basis, says de Araujo – they are not made up or imagined.”   One may however question this interpretation of the findings – why should visions that have a measurable neural correlate be considered more “real” that those in the inner vision?  One might instead say that the power to image or imagine is amplified by the medicine, just as it amplifies other modes of perception and cognition.

One Response

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