What are psychedelics actually doing? Some thoughts about future research challenges.

A fascinating recent article posted in Science Reports drew a lot of attention over the evidence that a higher state of consciousness had now been captured on MEG through the use of psychedelics.

The team on the paper – a collaboration between researchers at Sussex, Imperial, and Auckland – collected Magnetoencephalography (MEG) data from participants using Ketamine, LSD, and Psilocybin, and aimed to take a look at how a change in spontaneous signal diversity corresponded with the psychedelic subjective experience.

The essential conclusion was that Psilocybin, Ketamine, and LSD reflect an opposite pattern of neural diversity to anesthetics, such as propofol, and a greater level of spontaneous neural activity in comparison to normal waking consciousness – such as you’re using to read this – and so this might be called a more ‘signal rich’ mode of perceiving your conscious experience.

On top of being pretty novel in terms of its findings, the paper was a genuinely interesting way of looking at neural data, and works toward trying to pair phenomenological experience to brain activity in aid of understanding how our underlying perceptual machinery can produce such a strange experience – especially as consciousness has typically been studied through the loss of experience (such as anesthesia), and not often, if at all, through the increased complexity of experience compared to our every-day perceptions.

This paper has definitely got me thinking about the complex role of our brain to filter and define our incoming information moment to moment so that we can perform day-to-day tasks we take for granted, and how changes to this filtering might give us some fascinating insight into what’s actually going on under the hood.

It might also represent a different mode of signal detection, where otherwise ‘silent’ experiences and perceptions which would be otherwise ignored are now pushed up into our subjective platform.

Cognitive Neuropsychiatry takes a similar approach to this paper by studying the neural activity of individuals who have a very different experience of the world – such as in delusions – and using these findings to give us a clue as to the dynamics of related neural function e.g. belief formation.

This study adds to the field by demonstrating that instead of using individuals with a mental illness or neurological difficulty to peek behind the veil, we might be able to use psychedelics to transiently produce very different modes of subjectivity. This has huge potential, and I look forward to seeing where it progresses.

Image result for MEG machine

Magnetoencephalography (MEG) records the firing rhythms of the cortex. These different frequencies are given names like theta, delta, and alpha.
Image taken from MIT News


However – I do have some thoughts about challenges the field might face moving forward and some healthy criticism of the data – I hope this only helps to develop our interpretations.

Essentially, I think we need to be careful with getting carried away with the term ‘higher consciousness’ at this point, especially when trying to be true to the data, and the authors do indeed mention that the use of the phrase ‘higher state of consciousness’ is to be cautiously interpreted.

I see this as an issue on two related fronts.

First, as with anything, the media like to make a lot of hype around this finding, and it can be useful to be honest about some of the assumptions that we might attribute to what is actually being said.

For instance – when we hear the word ‘higher’, we might immediately associate this with being synonymous with ‘better’, or even more exotically, ‘enlightened’, as the suggestive image heading this blog post might portray.

But this is a tricky situation, as this plays into some potential assumptions about the quality of our conscious experience, for example, the idea that we need to somehow escape our ‘regular’ or everyday state of mind.

We could equally interpret our brain in its everyday state as an optimal and balanced organ working to reduce incoming information into digestible and manageable pieces which can be used to navigate the environment – much like that theorised in a new paper here.

Now, this isn’t to say that having interesting and rich experiences outside of our every-day can give us a whole new perspective on ourselves and insight into our malleable perceptions, or even that our ‘everyday’ mind can always be a good thing (e.g. outdated beliefs or overbearing self-criticism), but I fear associating this increased ‘free energy’ form with a more desirable function to be can lead to a ‘grass is greener’ type situation which ultimately gives our more everyday, and perhaps more mundane, experiences lesser value. But we need to remember that it’s these more typical experiences that give us the ability to do all the small things we take for granted (cue Blink 182).

Now I might be jumping the gun a little here as to how far most might take the idea of a ‘higher’ consciousness, or even over exaggerating the interpretations, but I think keeping on top of our exoticism over the experience can mean we don’t fetishise it and instead try to fully understand what this altered state actually is doing, and what this might mean for our understanding of the mind.

This leads into my next point, which is that the over exposure of the media may actually begin to bias the subjective experiences of future participants, and may greater amplify the placebo effect.

Neuroskeptic recently wrote an article addressing this issue with the recent APA consensus statement around the medicinal use of ketamine for depression.

Because of psychedelic research permeating most news outlets with tales of fascinating and powerful subjective experiences, we may all now be automatically biased toward what we expect from taking something like LSD.

Future experimentation aiming to further understand the correlation between subjective experience and symptom reduction will possibly find it increasingly harder to parse out expectation and the placebo effect from ‘drug related’ causal effects.

This isn’t to undermine the placebo experience as a useful and effective therapeutic tool, but if we are to get to the bottom of the causal neural mechanisms surrounding the use of psychedelics, massive expectations only work to muddy these results.

Questions might be being raised at this point between what we might consider ‘causal’ mechanisms, and whether we should make a distinction between ‘non-placebo’ neural changes as a hallmark of ‘genuine’ change as this might start bringing up a lot of false separations between our brain and subjective states, as each are one in the same, and doing so undermines the powerful effect of environment, social dynamics, and community belief.

My main question here is: is it the drug that is doing the driving of the experience, or is our expectation and our submission to the ritual process of taking it? If it’s the former, then it matters which drug we are administering, if its the latter, then psychedelics may not be as special as is often touted.

Of course, as with anything, it’s probably a mix of the two. However, if prior belief and expectation are found in future research to play a massive role in the changes in symptom changes, taking psychedelics in a modern medicinal setting with guidance may be conceptually on par with rituals we might not consider relevant in modernity anymore, like the Catholic mass or Sufi twirling – this is simply our modern take with lots of perceptual fireworks.

This might be quite a humbling piece of information, and serve to illustrate a) how powerful community consensus can be for therapeutic means, and b) how much we have in common with our previous generations.


This might appear antiquated to modern day 20- somethings, but is the key to a powerful psychological change belief, subjective prowess, and communal agreement?


My final point I hope illustrates my previous two, and it’s regarding the data presented in this study when looking deeper at the association made in the paper between the use of all three psychedelics, their effect of increased cortical signal complexity, and a large change in subjective experience.

Authors use a mathematical algorithm to analyse the MEG data called the ‘Lempel-Ziv complexity‘. This algorithm is essentially telling us how ‘random’ the neural signal generated from the brain is across 90 different sites – the assumption here is that the larger the value, the more complex, chaotic or ‘entropic’ the cortex is at that particular time – this is what the authors’ call a ‘richer’ or ‘higher state’ of consciousness because less filtering of our sensory experience is theorised to be occurring, and this is therefore suggested to accompany a vast change in subjective experience, such as the onset of hallucinations, ego-dissolution, and distortions in time and space.

Increased spontaneous signal diversity for PSIL, KET and LSD.
Figure 2(a) Mean scores across participants for the signal diversity measures LZsN, LZcN and ACEN are higher for each of the three drug conditions (white discs) than for the corresponding placebo conditions (black discs). A solid line across conditions indicates p < 0.001 and a dotted line 0.001 < p < 0.05, uncorrected, obtained from a two-sided t-test. (b) Difference in single channel Lempel-Ziv complexity, LZsN, between respectively PSIL, KET, LSD and placebo at the single participant level. The error bars indicate standard error across trials.
Image taken from : Schartner, M. M. et al. Increased spontaneous MEG signal diversity for psychoactive doses of ketamine, LSD and psilocybin. Sci. Rep. 7, 46421; doi: 10.1038/srep46421 (2017).


The above figure shows the difference in neural communication complexity using the algorithm I mentioned before. Notice that LSD and Ketamine both demonstrate significant differences between the drug condition (white discs under ‘a)’) and placebo condition (black discs under ‘a)’), but psilocybin doesn’t at all. This insignificance is compounded by the fact that individuals were actually scanned during their peak when you would expect the largest changes to be occurring.

This would suggest that for ketamine and LSD, changes in neural activity using this algorithm may reflect vastly different subjective experiences if we find a significant difference in participants phenomenological reports using the same drugs.

This would support the argument that the different compounds are having a different and meaningful neural impact.

Correlations across measures and questionnaire answers.

Figure 4

(a) For each drug, a matrix indicates in colour the Pearson correlation, r, of the score difference between drug and placebo condition (averaged across trials) of each measure pair across participants. The upper triangular entries and entries with |r| < 0.5 are omitted (and set white) to highlight strong correlations only. These correlations should be considered somewhat exploratory and are not controlled for multiple comparisons as each experiment had a limited sample size. Across drugs, signal diversity measures show high correlation with each other, yet inconsistently, as they capture different flavours of signal diversity. (b) Correlations between the changes in the measures ACEN, LZcN and LZsN and the questionnaire scores (same scale as above). No consistent correlation across drugs was found for any combination of the measure’s scores and scores for a particular question. (c) The changes in subjective ratings under each drug condition are shown as averages with standard error bars across subjects. The average of all changes across these 14 questions (except “InScanner”) is denoted as “total” and shown normalised by factor 20 in order to fit the scale. No consistent differences are apparent across drugs.
Image taken from : Schartner, M. M. et al. Increased spontaneous MEG signal diversity for psychoactive doses of ketamine, LSD and psilocybin. Sci. Rep. 7, 46421; doi: 10.1038/srep46421 (2017).


While all drugs showed an increase in signal diversity after drug administration, this hasn’t been established with significance at all for all drugs.

Now, the above figure suggests that psilocybin has the greatest total change in subjective experience compared to LSD and Ketamine, especially on experiences of seeing strange shapes, geometric patterns, and having vivid mental experiences.

As there was no significant difference between using psilocybin and placebo in terms of signal diversity, the fact that psilocybin expressed the greatest difference in subjective experience leaves me with alot of questions.

There still seems to be many questions regarding whether different compounds produce markedly different subjective experiences, and how this relates to symptoms reduction and neural activity.

The study however takes great steps to get the ball rolling in answering this question, and I look forward to seeing how these results develop, with different analyses, replications, and richer phenomenological reports being drawn upon to test these different hypotheses.

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MRC funded Neuropsychopharmacology PhD candidate

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