The Entropic Brain: Why Psychedelics Make the Mind More Flexible
Summary of of “The Entropic Brain: A Theory of Conscious States Informed by Neuroimaging Research with Psychedelic Drugs”
https://pmc.ncbi.nlm.nih.gov/articles/PMC3909994/
What if consciousness isn’t fixed—but varies in how ordered or disordered it is?
That’s the central idea behind a highly influential paper by Robin Carhart-Harris and colleagues, often referred to as the entropic brain theory.
It’s a deceptively simple proposal:
The richness and flexibility of conscious experience depend on how “entropic” (i.e., variable and less constrained) brain activity is.
And psychedelics, according to this theory, push the brain toward higher entropy—with profound effects on how we think, perceive, and feel.
The Core Idea: Consciousness Has Levels of Order
In everyday waking life, your brain is highly organized.
Patterns of activity are stable
Thoughts follow predictable paths
Perception is constrained and consistent
This is useful. It keeps you functional.
But the paper argues that this low-entropy state is just one mode of consciousness.
Under psychedelics like psilocybin, something changes:
Brain activity becomes more variable
Networks loosen their usual constraints
New patterns emerge
In short:
The brain becomes more entropic—more flexible, less rigid
Primary vs. Secondary Consciousness
The authors introduce an important distinction:
Secondary consciousness: normal waking state
Ordered
Stable
Constrained
Primary consciousness: psychedelic, dream-like, or early developmental states
Less ordered
More flexible
More associative
Psychedelics, they argue, temporarily shift the brain from secondary → primary consciousness.
This explains why experiences often feel:
More emotional
More vivid
Less bound by logic
Why Entropy Matters
“Entropy” here doesn’t mean chaos in a negative sense.
It means diversity of possible brain states.
A higher-entropy brain can:
Explore more mental configurations
Break out of rigid patterns
Generate novel associations
This has major implications.
In conditions like depression or addiction, the brain can become overly rigid—locked into repetitive loops of thought and behavior.
Psychedelics may help by:
Temporarily increasing entropy and allowing the system to “reset”
This aligns with modern findings that psychedelics increase the diversity of brain activity and disrupt rigid network patterns
The Ego and the Default Mode Network
One of the most discussed findings tied to this theory involves the default mode network (DMN)—a brain system associated with:
Self-reflection
Narrative identity
Ego
Under psychedelics:
DMN activity decreases
Its dominance over the brain weakens
The result?
Reduced sense of self
“Ego dissolution”
A more fluid sense of identity
This fits neatly with the entropic brain idea:
When rigid control systems relax, consciousness becomes more flexible.
From Neuroscience to Experience
The theory doesn’t just explain brain scans—it explains subjective experience.
Why do people report:
Seeing patterns and connections everywhere?
Feeling emotionally open or overwhelmed?
Experiencing unity or dissolution of boundaries?
Because the brain is:
Less constrained
More interconnected
More exploratory
In high-entropy states, the boundaries that normally organize experience begin to soften.
The Risk: Too Much Entropy
The paper is clear about one thing:
More entropy isn’t always better.
If the brain becomes too disordered, you get:
Confusion
Anxiety
Loss of coherent thought
In extreme cases, this may resemble:
Psychosis
Severe disorganization of perception
So the goal isn’t maximum entropy.
It’s flexible balance.
Why This Paper Matters
The entropic brain theory has become one of the most influential frameworks in psychedelic science.
It connects:
Neuroscience (brain activity patterns)
Psychology (experience and emotion)
Clinical research (treatment of mental disorders)
It also bridges earlier philosophical ideas—like those of Aldous Huxley—with modern data.
Huxley suggested psychedelics “open the reducing valve.”
Carhart-Harris suggests they increase entropy.
Different language.
Same intuition.
Final Take
The entropic brain theory reframes consciousness as something dynamic—not fixed.
Your normal waking mind is just one point on a spectrum:
Too ordered → rigid, repetitive
Too disordered → chaotic, unstable
In between → flexible, adaptive
Psychedelics push the brain toward the higher end of that spectrum.
And in doing so, they reveal something fundamental:
Consciousness is not just about what you experience—but how constrained your brain is while experiencing it.
Carhart-Harris RL, Leech R, Hellyer PJ, Shanahan M, Feilding A, Tagliazucchi E, Chialvo DR, Nutt D. The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs. Front Hum Neurosci. 2014 Feb 3;8:20. doi: 10.3389/fnhum.2014.00020. PMID: 24550805; PMCID: PMC3909994.