This shows a head.
But this sensation of detachment wasn't an out-of-body experience. Credit: Neuroscience News

Sense of Self: The Brain Structure That Holds Key to “I”

Summary: Researchers identified a small structure in the brain, the anterior precuneus or aPCu, as a crucial component in establishing our physical self or “I”.

The aPCu is part of a network of brain regions that integrate information regarding our location, motion, and bodily sensations to form our self-awareness. When electrical activity in the aPCu is disrupted, people experience altered perceptions of their position in the world.

The findings further our understanding of self-awareness and consciousness.

Key Facts:

  1. The anterior precuneus (aPCu) in the brain plays a critical role in forming our physical sense of self or “I”, as revealed by Stanford Medicine.
  2. When activity in the aPCu is disrupted, people’s perceptions of their place in the world dramatically change, invoking feelings of depersonalization.
  3. The aPCu works as part of a network of brain regions that integrate various types of bodily information to create our self-awareness.

Source: Stanford

Ever wonder where in your brain that interesting character called “I” lives? Stanford Medicine physician-scientist Josef Parvizi, MD, Ph.D., has news of its whereabouts.

If skulls were transparent, you still wouldn’t see much going on in someone else’s brain. But Parvizi has ways of peeking into people’s heads and finding out what makes us tick. His experiments have pinpointed specific brain regions crucial to capabilities ranging from perceiving faces to recognizing numerals.

Credit: Neuroscience News

Parvizi’s most recent sighting, described in a paper published June 8 in Neuron, unveils the surprising role of a small structure sandwiched between the brain’s two hemispheres.

The structure, called the anterior precuneus or aPCu, is the epicenter of a system of distributed brain regions that hum in synch—their activity rising and falling in coordination with one another’s, indicating teamwork.

(Spoiler alert: Speaking of rising and falling, stay tuned for a description of people’s altered perceptions of their place in the world when their aPCu gets fiddled with.)

Parvizi, postdoctoral scholar Dian Lu, Ph.D., and their colleagues discovered that this archipelago of collaborating brain regions spearheaded by the aPCu is crucial for integrating information about your location, motion, muscle and joint positions and sensations to form a mental map of your sense of bodily, or physical, self.

To explain the system’s significance, Parvizi invoked that odd couple, “I” and “me.”

“For every action we take, even during dreams,” he said, “there’s always an agent behind it: We call that agent ‘I’. ‘Me’ is everything we have stored in our memories about the ‘I'”.

The two selves

Neuroanatomically, there’s a separate archipelago of brain structures governing each. These two systems are continuously interacting with each other.

The physical/bodily sense of self—”I”—contrasts with another, narrative aspect of self—”me”—that has to do with actively or passively thinking about your past life or planning your future: things like memory, habits, personality, emotions, feelings for others, what lies ahead, etc.

The narrative self—”me”—dwells in a well-studied network called the default mode network. (To the non-specialist ear, the three words “default,” “mode” and “network” read like a trio of random words singing off-key. But the term actually makes sense: It designates a brain network that’s active when we’re daydreaming, recalling past events and so forth.)

There’s no official name yet for the bodily-self network, although it’s known to exist. Previous studies have highlighted a set of structures composing it, but didn’t say a lot about its now-apparent kingpin, the aPCu.

To further delineate the brain network captained by the aPCu, Parvizi’s team obtained brain-imaging data from five of his patient-participants as well as from nearly 1,000 participants in the Human Connectome Project, launched in 2010 to map the human brain’s neural connections.

“We’ve shown the precise location of key cells in the aPCu and, Dian’s map clearly shows how they connect with the rest of the brain,” Parvizi said.

The aPCU is located close to a brain structure that’s considered a key node in the default mode network. But it’s not part of that network, even though it communicates intensely with it.

“Electrically stimulating the default mode network doesn’t do anything at all to one’s sense of self or consciousness,” Parvizi said.

“Your sense of physical or bodily self represents your organism in the immediate here and now, with a particular point of view that is yours alone, your first-person perspective on the world around you. Nobody shares it,” Parvizi said.

“You may not be conscious of your point of view. But you will be if I disrupt the network that generates it. Your place in the world around you will suddenly seem unreal.”

Probing the brain

Parvizi makes his observations in his patients who are being evaluated for possible surgical treatment of recurring, drug-resistant epileptic seizures. Fine needles that serve as electrodes are inserted in the brain by a neurosurgeon under anesthesia.

Patients stay hooked up to the monitoring apparatus for several days, while the electrodes pick up electrical activity within the brain and report back to a computer.

The procedure eventually captures the inevitable repeated seizures, allowing neurologists to determine the exact spot in each patient’s brain where the seizures are originating. A substantial number of patients gain freedom from recurring seizures as a result of this invasive approach.

With these patients’ consent, Parvizi passes tiny pulses of current through a series of individual electrodes, stimulating or disrupting activity in tiny discrete patches of brain matter and watching what happens. (The procedure is safe and the brain feels no pain.)

One day a patient told him, “Every time I have a seizure, I have a sense of depersonalization and dissociation. Everything’s unreal, not happening to me.”

The patient’s seizures turned out to originate from the aPCu. Wanting to learn more about what was going on, Parvizi and his colleagues found eight more patients with implanted electrodes passing through their aPCu. The patients agreed to let him disrupt this structure’s activity with electrical pulses.

When he did that, Parvizi said, “All of them reported something weird happening to their sense of physical self. In fact, three of them reported a clear sense of depersonalization, similar to taking psychedelics.”

But this sensation of detachment wasn’t an out-of-body experience.

“In an out-of-body experience, you see yourself from the top,” Parvizi said.

“Our subjects did not report that at all. They still felt like they’re inside their bodies. But they typically reported a change in their sense of their location and orientation.

“If the right side of the brain was stimulated, they felt as though they were floating; if the left side was stimulated, they felt as if they were falling. As they looked around, it didn’t make sense.

“They shouldn’t be floating or sinking, but it felt like they were. The world around them seemed unreal.”

Oddly, patients’ reports of flying or floating versus falling or plunging were accompanied by relatively positive versus negative emotions, respectively, depending on whether the right or the left aPCu had been electrically stimulated. (Like many brain structures, the aPCu turns up on both hemispheres of the brain.)

“Why that happens, I have no clue,” Parvizi said. “I am absolutely puzzled why stimulating the left versus the right side elicits opposite effects, but we’re going to figure that out.”

About this consciousness and self-awareness research news

Author: Bruce Goldman
Source: Stanford
Contact: Bruce Goldman – Stanford
Image: The image is credited to Neuroscience News

Original Research: Open access.
Causal evidence for the processing of bodily self in the anterior precuneus” by Josef Parvizi et al. Neuron


Causal evidence for the processing of bodily self in the anterior precuneus


  • We studied anterior precuneus (aPCu) with fMRI, intracranial EEG, and electrical stimulations
  • Stimulation of aPCu caused distortions in core body schema and self-dissociation
  • Responsive aPCu sites were not part of, but were connected with, a default mode network
  • We present a brain-wide map of structures that are causally connected with the aPCu


To probe the causal importance of the human posteromedial cortex (PMC) in processing the sense of self, we studied a rare cohort of nine patients with electrodes implanted bilaterally in the precuneus, posterior cingulate, and retrosplenial regions with a combination of neuroimaging, intracranial recordings, and direct cortical stimulations.

In all participants, the stimulation of specific sites within the anterior precuneus (aPCu) caused dissociative changes in physical and spatial domains.

Using single-pulse electrical stimulations and neuroimaging, we present effective and resting-state connectivity of aPCu hot zone with the rest of the brain and show that they are located outside the boundaries of the default mode network (DMN) but connected reciprocally with it.

We propose that the function of this subregion of the PMC is integral to a range of cognitive processes that require the self’s physical point of reference, given its location within a spatial environment.

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  1. The question is whether those dissociative changes are indicative of the self or ‘I’. Did these investigations affect the ego? This would require a theory of the ego. In my opinion, mere empirical findings are not enough, because they are then arbitrary.

  2. How wonderful to read the discovery of the aPCu and its relation to I and Me.

    I have been studying, writing, and teaching human behavior as it applies to personal growth and business success for the last 50 years. It was most exciting to me to read that stimulating different sides of the brain created identifiable emotional effects.

    As have I taught, and demonstrated thousands of times in high percentage of individuals, our past (have experienced), is to our left and our future (have not experienced) is to our right. Could this be the answer to the researchers question, “Why does stimulating right or left sides of the brain have different emotional effects?”

    I propose this answer.

    That is, when stimulating the left side of the brain (Me) the subjects had negative shifts in perceptive reality. This is what is real, or known to us, therefore creating confusion and discomfort.

    And when stimulating the right side of the brain, (I) the subjects had positive shifts in alternated reality. As this, the future, is what most of us fear. We too often project our learned, negative not yet experienced, fears into the future. However, the study shows, when positively stimulated, we experience a form of euphoria free from our fears.

  3. Fun fact… the anterior precuneus is located at what we call “the crown of the head,” and this place is where a lot of religions always have some very heavy symbolism (I don’t know all of them, but here are some examples).

    1 – In Hinduism, it is the place of the Sahasrara, where the sense of “I” is destroyed and becomes one with the “All” when the coiled energy stored around the Coccyx flows upwards and joins the whole (Shiva) at the crown of the head. Yogis use matted hair on that location as a form of “insulation” so they can meditate without breaking once and for all the link with this world (Mahasamadhi). In Robert Svoboda account of the Aghoris, the final ritual they perform (where they attain mahasamadhi and die)… it is explained that when they attain the final goal, that part of the head ejects a jet of blood as they die.

    Funnier still: in Hinduism, there are two paths for enlightenment: the right-hand path (positive and calm, represented by deities like Saraswati and Vishnu) and the left-hand path (aggressive and terrifying, represented by Kali in scary forms).

    DMT users report an oppressive feeling of fear, and they also say they see a black dog or black wolf. In Hinduism, one of the scariest forms of Kali appears as a black wolf in some very dark rituals in cremation grounds using corpses. Perhaps the same region of the brain is activated (i.e., the left side of the anterior precuneus).

    2 – In Judaism, it is where the Kipá is worn.

    3 – In Catholicism, they have something similar to the Kipá, called the Zuccheto. Also, the crown used by Mary (Mother of Jesus) is placed in that region, not on the whole head (not always, but in many images).

  4. Some of the phrasing at the beginning of this article implies that one’s experience of one’s “physical self” is equivalent to one’s sense of “I.” Sorry, but this is a false equivalency error. When dreaming, I no longer experience my “physical self” yet I retain my sense of “I” or non-physical self-awareness. The article even quotes Parvizi as follows: “For every action we take, even during dreams, there’s always an agent behind it: We call that agent ‘I’. ‘Me’ is everything we have stored in our memories about the ‘I.‘“ In other words, Parvizi acknowledges that during non-physical dreaming, a sense of self is retained. Additionally, the article quotes one of the test subjects as follows: “Every time I have a seizure, I have a sense of depersonalization and dissociation. Everything’s unreal, not happening to me.” Ergo, the test subject states that during the “depersonalization and dissociation” experience, they retain a sense of self or “me.” All that this study implies is that the aPCu is responsible for integrating one’s consciousness into one’s bodily experience as a single entity — it isn’t responsible for one’s sense of non-physical self or “I.”

    1. I agree with this take. It sounds more like the aPCu is in charge of the proprioceptive-like sensation of consciousness, but that’s about all this seems to show.

      1. Interesting thoughts and well written. I am healing from dissociation and depersonalization and find some associations with my somatic and reintegration experience.

  5. This is off the wall, but if one or more of you might humor me, I’d appreciate it.

    I am seriously perceptive and conceptual but not an MD or shrink. I’m writing my third novel in which the protagonist is a psychiatrist. He is called to the ER for a psych consult and determines that the patient is not truly suicidal or dangerous and dismisses her. She then goes out and calmly and successfully kills herself.

    During their conversations, she reveals a history of making up fake names for herself and attempting to start over in life. The names are clever, like Beverly Hill and Penny Nichols.

    So, I’m wondering if she might have a derailed sense of self which might lead to her being unable to distinguish between rational and irrational. The book is not about psychiatry but about the doctor’s attempt to deal with what he perceives as a colossal and fatal personal and professional failure. Additional characters, events, and adventures ensue, of course. The title of the novel will be Alas Prometheus.

    Any thoughts any of you might toss my way would be enormously appreciated. Thank you.

    1. It’s nice to have a writer contact us.

      I’d take a look into personality disorders as some of them are associated with identity disturbances. Borderline personality disorder (BPD) and Histrionic personality disorder (HPD) may be good starting points.

      Good luck with your writing!

    2. I would be careful about “creating personalities”. The Dissociative Disorder Community (which includes not only Dissociative Identity Disorder, Other Specified Dissociative Disorder, Unspecified Dissociative Disorder, Dissociative Amnesia, but also Depersonalization/Derealization – which is discussed in the article) are often maligned in media and art.

      I understand that your protagonist is not the one who creates these personalities, I just think you should communicate with someone from the Dissociative Disorder Community to more carefully flesh out your character.

      Your perspective of the patient is very important, and even addresses TWO very dangerous reality for those of us who have DID, OSDD, and UDD… The first, a disregard from the medical community – even by some in the mental health community: We often fail to get taken seriously or fail to be treated with Trauma Informed Care. The second the incredibly high incidence of suicide amount the Dissociative Disorder Community, as well as those with BPD (who are often misdiagnosed as having BPD ALONE, rather than in combination with Dissociative Disorder , or just outright Dissociative Disorder .)

      Unless your patient is malingering – which is another problem altogether! However, as someone from the Dissociative Disorder Community, I would ask, for the safety and credibility of so many of us, please do NOT let her be a malingerer of a Dissociative Disorder. There are so many who already dismiss us, or outright call us liars. Our suffering comes from early childhood trauma. All these people do is retraumatize us and reinforce the idea that we don’t need the care we need. Don’t be like them.

      Personally, I’m very curious if and/or how this aPCu might be implicated in Dissociative Disorders, since those of us who struggle and live with this so often have a lost sense of self and identity; and the researchers also talk about patients experiencing dissociation… My question comes in part because in the mid 90’s, those writing this section of the DSM4(?), recognized that Multiple Personality Disorder was not so much a personality disorder, but more of a *dissociative* disorder, so they renamed MPD to DID and so on. Not only that, but as fMRI’s were done on people with DID, it was found to be in the general area, yet just beyond were PTSD & CPTSD is typically “found” on these types of brain scans.

      Returning to your idea for a novel, the “creative beauty” is that each Dissociative Disorder System is unique, and so many are covert – because this is not only a maligned disorder, it hides in plain sight. I’d recommend for information, including the statistical prevalence of Dissociative Disorders in the general population (which can range between 10-13% .) Why unique? Because each brain is unique, what one person finds traumatic may not faze another, and no two traumas will be the same: location, age, cause/perpetrator, violence… So the brain will decide what the child needs to survive. Another thing of note is that these Dissociative Disreders cannot form after the onset of early puberty – most often between 7-10 years old. Oh! And Alters are usually NOT violent towards others outside their System. In fact they are far more likely to be violent and a danger to the body (self harm from ED to pretty much anything imaginable) and their own System (deprivation, hatred, demeaning violence…).

      Hope this helps!

  6. Do animals have a similar network of neurons that would allow them to have a sense of “self”? Animals seem to have a sense of self when they recognize another animal as one of their own species, which is a consistent and dramatic recognition of “one of their own”, but also within species, they recognize their status in relation to others within their social group. It would seem that this definitely qualifies as a sense of self. Also, they recognize their individual name being called from within a group of consorts with different given names. Is there a consensus on this?

  7. It’s becoming clear that with all the brain and consciousness theories out there, the proof will be in the pudding. By this I mean, can any particular theory be used to create a human adult level conscious machine. My bet is on the late Gerald Edelman’s Extended Theory of Neuronal Group Selection. The lead group in robotics based on this theory is the Neurorobotics Lab at UC at Irvine. Dr. Edelman distinguished between primary consciousness, which came first in evolution, and that humans share with other conscious animals, and higher order consciousness, which came to only humans with the acquisition of language. A machine with primary consciousness will probably have to come first.

    What I find special about the TNGS is the Darwin series of automata created at the Neurosciences Institute by Dr. Edelman and his colleagues in the 1990’s and 2000’s. These machines perform in the real world, not in a restricted simulated world, and display convincing physical behavior indicative of higher psychological functions necessary for consciousness, such as perceptual categorization, memory, and learning. They are based on realistic models of the parts of the biological brain that the theory claims subserve these functions. The extended TNGS allows for the emergence of consciousness based only on further evolutionary development of the brain areas responsible for these functions, in a parsimonious way. No other research I’ve encountered is anywhere near as convincing.

    I post because on almost every video and article about the brain and consciousness that I encounter, the attitude seems to be that we still know next to nothing about how the brain and consciousness work; that there’s lots of data but no unifying theory. I believe the extended TNGS is that theory. My motivation is to keep that theory in front of the public. And obviously, I consider it the route to a truly conscious machine, primary and higher-order.

    My advice to people who want to create a conscious machine is to seriously ground themselves in the extended TNGS and the Darwin automata first, and proceed from there, by applying to Jeff Krichmar’s lab at UC Irvine, possibly. Dr. Edelman’s roadmap to a conscious machine is at

  8. Fascinating. My reads an psychedelics, meditation and the book “The Master and his Emissary” start interacting with this in my mind

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