The default mode network is one of the most studied structures in modern neuroscience, and it is central to how researchers currently explain why psychedelics can produce experiences that feel — and sometimes measurably are — durable rather than transient. This piece walks through what the DMN actually is, what the peer-reviewed literature reports about psychedelics' effect on it, and where the strong claims outrun the evidence.
Learn what actually happens during the ayahuasca ceremony itself — ritual structure, facilitator's role, the purge, and next-morning integration.
What the DMN Is
The default mode network — first formally described by Raichle and colleagues in the early 2000s — is a set of brain regions including the medial prefrontal cortex, posterior cingulate cortex, and precuneus, along with parts of the inferior parietal lobule and medial temporal lobe. It is the network that is most active when a person is notexternally focused: when they are remembering, planning, imagining the future, or thinking about themselves and other people.
The DMN in Depression
A large body of resting-state fMRI research has associated depression with altered DMN activity — often described as hyperconnectivity within the network and difficulty disengaging from self-referential thought. Persistent rumination is not just a symptom of depression; it appears to be tied to the way the DMN is functioning. Hamilton et al. (Biological Psychiatry, 2015) reviewed the evidence linking DMN activity to depressive rumination and argued that DMN dynamics may represent a mechanistically meaningful target for intervention rather than a downstream correlate.
What Psychedelics Appear to Do
In a series of neuroimaging studies beginning in 2012, Robin Carhart-Harris and colleagues reported that psilocybin acutely reduces blood flow and coordinated activity in DMN hub regions, while increasing communication between networks that are normally more segregated from each other. Related studies have reported similar effects with LSD and ayahuasca (Palhano-Fontes et al., PLoS One, 2015). The 2014 paper "The entropic brain" proposed a broader framework: that classical psychedelics increase the diversity of moment-to-moment brain states — a rise in neural "entropy" — and that the DMN's loosened grip is one signature of that shift.
The 2022 Longitudinal Follow-up
Daws, Timmermann, and colleagues (Nature Medicine, 2022) followed patients treated with psilocybin for depression and reported that the acute reduction in DMN integrity was followed, at three weeks, by increased functional connectivity between the DMN and other networks — and that the magnitude of that change correlated with clinical improvement. This is one of the first datasets to link the acute neuroimaging signature to a longer-term clinical outcome in the same participants, and it moves the DMN story from correlation toward mechanism.
Why That Might Produce Lasting Change
If the DMN is the substrate of habitual self-narrative, and depression involves a stuck, inward-turned version of that narrative, then a temporary, supported disruption of the DMN may open a window in which patterns can reconfigure. This is the working hypothesis behind much of contemporary psychedelic therapy research, and it is consistent with the clinical observation that the subjective intensity of the experience often correlates with clinical outcome. It also explains why "set and setting" — preparation, environment, integration — are treated as clinically relevant rather than peripheral.
What the Evidence Does Not Say
The evidence does not support the strong claim that a single psychedelic experience permanently "resets" the brain. What it supports is: acute DMN disruption during the experience, meaningful correlations between that disruption and subjective and clinical outcomes, and — in the case of psilocybin for depression — genuine but still-early evidence of sustained effects in controlled trials. The DMN framework is a promising organizing story for what these compounds do, but it is not a completed neuroscience.
Why the DMN Is Not the Whole Story
The DMN framework is useful but incomplete. Psychedelics also modulate the salience network, the frontoparietal control network, and thalamocortical connectivity, and the broader finding across neuroimaging studies is that between-network segregation decreases while moment-to-moment global integration increases. The "loosened DMN" story captures one striking piece of that broader shift, but it is not the whole shift. Newer analyses using dynamic functional connectivity and complexity measures argue that what really changes on psychedelics is the diversity of accessible brain states over time, of which DMN disintegration is a signature rather than the cause.
Ego Dissolution as a Correlate
One of the more replicated findings across the neuroimaging literature is that the degree of subjective ego dissolution during a psychedelic experience correlates with the degree of acute DMN disintegration measured on fMRI. This is a rare instance of a subjective psychological construct — the felt loss of ordinary self-boundaries — mapping onto a specific neural signature. It doesn't prove the DMN is the seat of the self; it does suggest the DMN is a load-bearing substrate for the ordinary sense of continuous self-narrative that ego dissolution disrupts. Whether that dissolution is therapeutically necessary, or merely correlated with therapeutic outcome, is one of the open questions the Phase 3 trials will help answer.
Implications for Practice
If the working hypothesis — acute network disruption creates a plasticity window that integration then consolidates — is even approximately right, several practical implications follow. The pre-session state matters: entering the experience anxious or distracted biases which regions are active and which shift. The environment matters: external context shapes what the loosened network reorganizes toward. And the integration period matters: what a patient does with new patterns of thought and feeling in the days and weeks after a session probably determines whether the acute change consolidates or dissipates. None of this is unique to psychedelic therapy — it is standard for any intervention that produces a temporary window of increased plasticity — but it is why responsible programs treat set, setting, and integration as parts of the treatment rather than accessories to the drug.
A Brief Note on Sanctuary Tulum
Sanctuary Tulum's work with ayahuasca, ibogaine, 5-MeO-DMT, and psilocybin is framed around preparation, medically supervised administration, and integration — the parts of the process the neuroscience suggests actually matter. For details, see our ayahuasca retreat, psilocybin therapy, and 5-MeO-DMT ceremony pages.
References
- Raichle ME, MacLeod AM, Snyder AZ, Powers WJ, Gusnard DA, Shulman GL. "A default mode of brain function." Proc Natl Acad Sci USA. 2001;98(2):676–682.
- Carhart-Harris RL, Erritzoe D, Williams T, et al. "Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin." Proc Natl Acad Sci USA. 2012;109(6):2138–2143.
- Carhart-Harris RL, Leech R, Hellyer PJ, et al. "The entropic brain." Front Hum Neurosci. 2014;8:20.
- Palhano-Fontes F, Andrade KC, Tofoli LF, et al. "The psychedelic state induced by ayahuasca modulates the activity and connectivity of the default mode network." PLoS One. 2015;10(2):e0118143.
- Hamilton JP, Farmer M, Fogelman P, Gotlib IH. "Depressive rumination, the default-mode network, and the dark matter of clinical neuroscience." Biol Psychiatry. 2015;78(4):224–230.
- Daws RE, Timmermann C, Giribaldi B, et al. "Increased global integration in the brain after psilocybin therapy for depression." Nat Med. 2022;28(4):844–851.
