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Study on LSD, mental time travel & the DMN

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Bancopuma

Bancopuma

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New fresh off the press study on LSD, and it's a positive and interesting one...evidence for beneficial applications and effects of LSD continues to build.

Speth, J., Speth, C., Kaelen, M., Schloerscheidt, A.M., Feilding, A., Nutt, D.J. & Carhart-Harris, R.L. (2016) Decreased mental time travel to the past correlates with default-mode network disintegration under lysergic acid diethylamide. Journal of Psychopharmacology, 30, (4), 344-353

Abstract

This paper reports on the effects of LSD on mental time travel during spontaneous mentation. Twenty healthy volunteers participated in a placebo-controlled crossover study, incorporating intravenous administration of LSD (75 μg) and placebo (saline) prior to functional magnetic resonance imaging (fMRI). Six independent, blind judges analysed mentation reports acquired during structured interviews performed shortly after the functional magnetic resonance imaging (fMRI) scans (approximately 2.5 h post-administration). Within each report, specific linguistic references to mental spaces for the past, present and future were identified. Results revealed significantly fewer mental spaces for the past under LSD and this effect correlated with the general intensity of the drug’s subjective effects. No differences in the number of mental spaces for the present or future were observed. Consistent with the previously proposed role of the default-mode network (DMN) in autobiographical memory recollection and ruminative thought, decreased resting-state functional connectivity (RSFC) within the DMN correlated with decreased mental time travel to the past. These results are discussed in relation to potential therapeutic applications of LSD and related psychedelics, e.g. in the treatment of depression, for which excessive reflection on one’s past, likely mediated by DMN functioning, is symptomatic.

Link:


Article:

www.iflscience.com

LSD Could Help Fight Depression By Inhibiting "Mental Time Travel”

LSD Could Help Fight Depression By Inhibiting "Mental Time Travel”
www.iflscience.com www.iflscience.com
 
Normally I'm generally very enthusiastic about Dr. Carhart-Harris' research, and I'm really excited to see what other data they got from the LSD fMRI sessions, but I just don't buy the validity of this particular study.

I read it when it was first released, and the methods are way too vague. I don't think we have a deep enough understanding of psycholinguistics to get useful data out of coded transcripts. It's a nice thought, but right now it's just too flaky.

Sometimes I forget that the good doctor is actually into psychoanalysis, and then I remember and get sad. His work with Petri was much more interesting, and rigorous.

Blessings
~ND
 
Hey ND,

Have you read the whole paper? (Attached). I'm not sure about the level of Dr Carhart-Harris' involvement in this study. I kinda hear where you're coming from, but I guess science needs to use the tools it has available to it at the time...perhaps research like this can lead to inroads on how to refine the methodologies uses in future studies.
 

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Bancopuma said:
Hey ND,

Have you read the whole paper? (Attached). I'm not sure about the level of Dr Carhart-Harris' involvement in this study. I kinda hear where you're coming from, but I guess science needs to use the tools it has available to it at the time...perhaps research like this can lead to inroads on how to refine the methodologies uses in future studies.
Click to expand...
I don't know about in the UK, but in the US, the last author is usually the PI of the lab the work took place in, the first author is the primary experimenter, and all the ones in between are people who helped out with the project in lesser capacities. First and last authors usually get equal credit. I just assumed that this was coming out of Carhart-Harris' lab, and I know for a fact that he was involved in spearheading the LSD-fMRI study. I could be wrong though.

The fMRI data was more interesting to me (although this xkcd comic communicates a lot of my problems with giving too much weight to fMRI studies at all), but correlating that with mental time travel seemed specious to me.

Blesings
~ND
 
I guess it's a tricky thing to study though in some respects, and as fascinating as the brain imaging studies are, they can only take you so far, and this more subjective component of the research is perhaps necessary? It is worth having a go at linking the changes observed in the brain via fMRI with perceived changes in one's outlook, and I think the only way of obtaining this information is via the structured interviews following the fMRI scans that were performed. Personally, I think this research is interesting, as it is hinting that the LSD state is one that tends to put one in a mindful state, and there is research already out there linking psilocybin, meditation and time in nature to mindful states and the same lowered activity in the DMN, coupled with lowered measures anxiety and depression. I find the overlap between these different things interesting.
 
Consistent with the previously proposed role of the default-mode network (DMN) in autobiographical memory recollection and ruminative thought, decreased resting-state functional connectivity (RSFC) within the DMN correlated with decreased mental time travel to the past.

Fascinating!!!! Meditation is observed to decrease activity of the DMN as well! And if such decreased activity of the DMN is associated with less "living in the past" then it makes sense these ancient teachings regarding subjective experiences of living completely in the present vs the past vs the future. Lucid dreaming, according a couple of books I'm reading at present, achieves the exact same effect seen in the brains of psychedelicists.

On my first experience ever with a psychedelic (with mescaline), I experienced a difficult time teasing apart the realities I was generating in my imagination and the reality of the present moment distinct from my "mapping over it with thought-images". Perhaps the role of DMN in regard to mental time traveling (think-imaging in terms of the past - now - future) is related to this phenomenon.

I think most psychedelic experimenters have had the early experience of total terror of wondering whether you really are in bed right now, or are actually dead on the side of a road. Maybe all this is related to the functional deactivation of the DMN, correlating to the effect of not being to mentally travel back in the past, to "check" the memory of "not having" wondered away from your house and gotten into trouble.

To me, this makes perfect sense; the scientific neurological data syncs very nicely with my experience!
Anyone else agree?
 
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