Research into psychedelics In recent years, has focused not only on subjective experiences but also on the question of what these substances do to the organization of brain networks in the short term. A recent publication in Molecular Psychiatry used ultra-high resolution 7 Tesla fMRI to compare the acute effects of 2C-B and psilocybin in healthy volunteers. This is interesting because psilocybin is relatively well studied, whereas 2C-B has much less data in the scientific community.
In this article, we explain what was measured in this 7T fMRI study, what the key findings are, and what limitations you should keep in mind. It is important to emphasize immediately: this was no treatment study and therefore it says nothing directly about therapy results or clinical applicability.
What made this 7T fMRI study special?
The researchers used 7 Tesla Resting-state fMRI is a type of brain scan used to map patterns in brain activity and connections between brain regions while a person lies still without performing a task. 7T scanners generally provide more detail than the more common 3T scanners, although this higher sensitivity also brings technical challenges (for example, increased sensitivity to motion and artifacts).
The study design was double-blind, randomized, placebo-controlled, and had a crossover design. The same participants received at different times 20 mg 2C-B, 15 mg psilocybin and placebo. A total of 22 people participated, resulting in 20 usable datasets after quality control.
This type of design is highly suitable for fundamental neurobiology because individual differences are partially accounted for, as participants serve as their own comparison. At the same time, the sample size remains relatively small, which is important when interpreting subtle differences between substances.
Which brain measures were examined?
In the public conversation about psychedelics, the focus is often on “more connections in the brain” or “the default mode network switching off.” In scientific research, the situation is more nuanced. In this study, researchers looked at, among other things:
Static functional connectivity: average association between areas over a measurement period.
Dynamic functional connectivity: how that coherence fluctuates over time. Psychedelic states are often associated with more variability in network states, but that depends on method and interpretation.
Global connectivity: a measure of how strongly an area is connected to the rest of the brain on average.
Complexity of spontaneous BOLD signals: a way to describe how predictable or varied brain signals are. Important: “more complexity” does not automatically mean “better”. Rather, it indicates a shift in dynamics and predictability.
Because this is fundamental brain research, it is therefore not about symptoms or treatment outcomes, but about neurobiological patterns that may shed light on how psychedelic states are “supported” by brain networks.
Key finding: less cohesion within networks, more between networks
A central finding was that both 2C-B and psilocybin clearly altered the functional organization of the brain compared to placebo. Broadly speaking, the researchers observed two movements that frequently recur in psychedelic research:
1) Less cohesion within some networks
With both agents, connectivity within certain networks decreased, including in visual networks and parts of the default mode network (DMN). In plain language: areas that collaborate more strongly “as a team” within a network under a placebo appear temporarily somewhat less tightly clustered.
2) More connections between networks
At the same time, connections between different networks increased, including connections between subcortical and cortical areas. This aligns with the idea that psychedelics can cause temporary “network desegregation”: boundaries between networks become less strict, increasing information exchange between normally more separated systems.
In the literature, these patterns are sometimes linked to changes in perception, associative thinking, and the experience of meaning. However, it remains important to take that step cautiously: fMRI shows correlations in signals, not direct causal chains of “network X causes experience Y”.
Not identical: psilocybin and 2C-B each had their own pattern
Although both substances had overlapping effects, it was not simply “the same picture”. In this study, some intermediate network effects appeared to occur under psilocybin. broader and stronger than under 2C-B. At the same time, 2C-B actually showed at certain places specific increases see, for example in connections between parts of the DMN and the frontoparietal network (a network often involved in attention and cognitive control).
That is a relevant nuance in discussions about psychedelics. Substances can be placed in the same “family” based on subjective effects, yet still exhibit their own distinct neurobiological profile. It suggests that the label “psychedelic” does not automatically mean that all substances have the same effect on the brain.
More complexity in brain signals: what does that mean?
A second main finding was that both 2C-B and psilocybin the complexity spontaneous BOLD signals increased, including in visual and thalamic areas. The researchers observed no clear difference between the two substances in this regard.
In some theories, complexity is viewed as a neurobiological marker of a state in which the brain is less “stuck” in fixed patterns. This may align with the phenomenon that people report more variation, intensity, or flexibility in thoughts, images, and associations during psychedelic experiences.
At the same time, it is important not to attach value judgments to this measure too quickly. More complexity is not synonymous with improvement or health. It is primarily a description of a temporary shift in the dynamics of brain signals.
Subjective experience: comparable intensity, yet differences
The researchers attempted to select doses that would be approximately comparable in terms of acute psychoactive strength. Around the time of the fMRI scan, intensity measurements were also comparable. Nevertheless, participants reported more general altered-state effects and more anxious ego dissolution retrospectively under psilocybin than under 2C-B.
That is an interesting point, even apart from any therapeutic context. It shows that “equally strong” at a single point in time is not the same as “equally burdensome” or “equally intense” over the entire experience. Differences in duration, emotional charge, and type of effects can be significant, even when people report comparable intensity during a specific time window.
Please note: this type of subjective reporting is valuable, but it remains sensitive to expectations, prior experiences, and set and setting. The study makes no claims about what is “better” or “worse,” only that differences were reported.
Why receptors and transporters were included
A striking aspect of this study is that the fMRI results were compared with PET maps of receptor and transporter density. Among psychedelics, the focus is often on the 5-HT2A receptor (serotonin), because it is strongly involved in classic psychedelic effects. In this study, the researchers found that changes in dynamic connectivity in both substances were spatially associated with 5-HT2A density.
At the same time, they observed that differences between 2C-B and psilocybin might be partly related to other systems, including 5-HT1A and the dopamine transporter THAT. This is not definitive proof of causality, but it does fit a broader trend: psychedelic effects cannot always be traced back to a single receptor. In addition to overlap, substances can also have unique pharmacological “signatures.”.
There is also an important uncertainty here: for 2C-B, there is not yet a strong basis of in vivo receptor occupancy data. As a result, some interpretations remain indirect and provisional.
What you can and cannot conclude from this study
Well: This study supports the finding that both 2C-B and psilocybin cause acute, measurable changes in brain networks, with both overlap and differences. It also shows that 2C-B can be scientifically investigated using modern neuroimaging and that it exhibits “psychedelic-like” patterns to multiple degrees.
Not: This study demonstrates no therapeutic effect, says nothing about safety in non-research contexts, and is no basis for drawing conclusions regarding the treatment of trauma, depression, or anxiety. The participants were healthy volunteers, and the outcome measures concerned brain organization, not clinical improvement.
An additional nuance is the sample size. With relatively few participants, effects may be missed or, conversely, appear unstable. “No significant difference” does not automatically mean “no difference” here.
From fundamental brain research to practice: why harm reduction remains important
Fundamental research helps to better understand what psychedelics do to brain organization in the short term. However, the step from scanner data to practical application is a big one. Context, screening, guidance, dosage, duration, and aftercare are all factors that cannot be deduced from fMRI alone.
Furthermore, for MDMA, sessions are currently only indoors. scientific research or in practice in a harm-reduction context can be discussed and shaped. That distinction is important: scientific research has strict protocols, while harm reduction focuses on risk reduction and practical safety without therapeutic claims or guarantees.
Those who are exploring guided sessions more broadly and want to understand the differences between frameworks can read the explanation about how MDMA sessions are still possible. This is not an invitation to use, but a way to keep facts, limitations, and safety thinking clear.
Conclusion
This 7T fMRI study shows that 2C-B and psilocybin alter the functional organization of brain networks in similar, but not identical, ways. Both substances appear to temporarily make network boundaries less strict and increase the complexity of brain signals. At the same time, the study points to substance-specific patterns and subjective differences, even at comparable acute intensity.
The most important nuance remains: this concerns fundamental research with healthy volunteers, not evidence for treatment or therapeutic application. Those wishing to delve into guided sessions from a harm-reduction perspective and explore whether signing up feels appropriate within that context can visit sign up for MDMA session.
Source for this article: 2C-B and psilocybin alter brain networks in similar, but not identical ways.
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