Scientists solving the mystery of human consciousness

Awakening from anesthesia is often associated with an initial phase of delirious struggle before the full restoration of awareness and orientation to one’s surroundings. Scientists now know why this may occur: primitive consciousness emerges first. Using brain imaging techniques in healthy volunteers, a team of scientists led by Adjunct Professor Harry Scheinin, M.D. from the University of Turku, Turku, Finland in collaboration with investigators from the University of California, Irvine, USA, have now imaged the process of returning consciousness after general anesthesia. The emergence of consciousness was found to be associated with activations of deep, primitive brain structures rather than the evolutionary younger neocortex.

These results may represent an important step forward in the scientific explanation of human consciousness. The study was part of the Research Programme on Neuroscience by the Academy of Finland.


Caption: This image shows one returning from oblivion — imaging the neural core of consciousness. Positron emission tomography (PET) findings show that the emergence of consciousness after anesthesia is associated with activation of deep, phylogenetically old brain structures rather than the neocortex. Left: Sagittal (top) and axial (bottom) sections show activation in the anterior cingulate cortex (i), thalamus (ii) and the brainstem (iii) locus coeruleus/parabrachial area overlaid on magnetic resonance image (MRI) slices. Right: Cortical renderings show no evident activations.

Credit: Turku PET Center

“We expected to see the outer bits of brain, the cerebral cortex (often thought to be the seat of higher human consciousness), would turn back on when consciousness was restored following anesthesia. Surprisingly, that is not what the images showed us. In fact, the central core structures of the more primitive brain structures including the thalamus and parts of the limbic system appeared to become functional first, suggesting that a foundational primitive conscious state must be restored before higher order conscious activity can occur” Scheinin said.

Twenty young healthy volunteers were put under anesthesia in a brain scanner using either dexme-detomidine or propofol anesthetic drugs. The subjects were then woken up while brain activity pictures were being taken. Dexmedetomidine is used as a sedative in the intensive care unit setting and propofol is widely used for induction and maintenance of general anesthesia. Dexmedetomidineinduced unconsciousness has a close resemblance to normal physiological sleep, as it can be reversed with mild physical stimulation or loud voices without requiring any change in the dosing of the drug. This unique property was critical to the study design, as it enabled the investigators to separate the brain activity changes associated with the changing level of consciousness from the drugrelated effects on the brain. The staterelated changes in brain activity were imaged with positron emission tomography (PET).

The emergence of consciousness, as assessed with a motor response to a spoken command, was associated with the activation of a core network involving subcortical and limbic regions that became functionally coupled with parts of frontal and inferior parietal cortices upon awakening from dexme-detomidine-induced unconsciousness. This network thus enabled the subjective awareness of the external world and the capacity to behaviorally express the contents of consciousness through voluntary responses.

Interestingly, the same deep brain structures, i.e. the brain stem, thalamus, hypothalamus and the anterior cingulate cortex, were activated also upon emergence from propofol anesthesia, suggesting a common, drugindependent mechanism of arousal. For both drugs, activations seen upon regaining consciousness were thus mostly localized in deep, phylogenetically old brain structures rather than in the neocortex.

The researchers speculate that because current depth-of-anesthesia monitoring technology is based on cortical electroencephalography (EEG) measurement (i.e., measuring electrical signals on the sur-face of the scalp that arise from the brain’s cortical surface), their results help to explain why these devices fail in differentiating the conscious and unconscious states and why patient awareness during general anesthesia may not always be detected. The results presented here also add to the current understanding of anesthesia mechanisms and form the foundation for developing more reliable depth-of-anesthesia technology.

The anesthetized brain provides new views into the emergence of consciousness. Anesthetic agents are clinically useful for their remarkable property of being able to manipulate the state of consciousness. When given a sufficient dose of an anesthetic, a person will lose the precious but mysterious capacity of being aware of one’s own self and the surrounding world, and will sink into a state of oblivion. Conversely, when the dose is lightened or wears off, the brain almost magically recreates a subjective sense of being as experience and awareness returns. The ultimate nature of consciousness remains a mystery, but anesthesia offers a unique window for imaging internal brain activity when the subjective phenomenon of consciousness first vanishes and then re-emerges. This study was designed to give the clearest picture so far of the internal brain processes involved in this phenomenon.

The results may also have broader implications. The demonstration of which brain mechanisms are involved in the emergence of the conscious state is an important step forward in the scientific explanation of consciousness. Yet, much harder questions remain. How and why do these neural mechanisms create the subjective feeling of being, the awareness of self and environment the state of being conscious?


10 thoughts on “Scientists solving the mystery of human consciousness

  1. If we needed any more proof I’d say this demonstrates evolution in action. The organism develops the simplest and most necessary survival mechanisms over millions and millions of years before it develops the mechanism that enables it to become conscious of its surroundings. I believe this response as observed demonstrates that “conscioness” develops in response to the complexity of surviving in an ever more complex and demanding physical enviroment.

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  3. Anirudh Kumar Satsangi


    What is consciousness? We should define it first. Just as heat or smoke are symptoms of fire, so consciousness is symptom of soul or spirit. The energy of the soul or self is produced in the shape of consciousness. Indeed consciousness proves that the soul is present. This is not only the philosophy of Bhagavad-gita but the conclusion of all Vedic Literature including all Eastern Philosophy.

    Consciousness is both physical and spiritual.
    “Physicist Roger Penrose and neurophysiologist Stuart Hameroff claim that consciousness emerges from quantum-level elements of the brain’s cytoskeleton. The cytoskeleton is a protein based structure that maintains the integrity of living cells, including neurons. The neurons in the brain are organize into a network of microtubules of microscopic size but astronomical number. The network of microtubule is known a s “microtrabecular lattice”. It could be responsible for the quantum-receptivity of our brain, picking up, transforming, and interpreting information based on phase-conjugate resonance. But I feel that this is contrary to all religious belief particularly Eastern Philosophy. Penrose-Hameroff Model of Quantum Consciousness deals with physical consciousness. In this model brain receives (quantum -hologram receptivity) information and process them. In this model physical consciousness dominates over spiritual consciousness. The domain of physical consciousness extends up to the region of Brahmn. In English Brahmn means ever expanding. This region was created after the first Big Bang and the universe is expanding ever since. Ever expanding means ever changing. Quantum theory can be applied in this region since it deals with probability.

    Spiritual consciousness deals with Self-Realization. In State of Samadhi, when soul transcends for journey into higher spiritual regions brain does not accompany Soul. It is the Soul only which realizes Itself. However, brain of the enlightened persons gets the knowledge of this experience simultaneously. It is worth mentioning here that in disembodied spirits (subtle body) there is no brain but they receive information and process them and also sometimes communicate with us. So Quantum Theory cannot be applied at the level of Spiritual Consciousness.

    His Holiness Maharaj Sahab (1861-1907) wrote in Dicourses on Radhasoami Faith: “During satyauga, the creational current, having freshly descended into the third division, was highly charged with the spiritual energy which it infused in every form of animate and inanimate existence…………………………

    And the human entities, in consequence of their comparatively greater spirituality and of high purity of their heart, had no difficulty in getting access at times into the astral planes and holding communion with the departed spirits. This yuga was of the longest duration” Here again there’s no brain in departed spirits and no neural or cortical activity is involved in holding communion into the astral planes. This experience is purely at spiritual level. This is the difference in physical consciousness and spiritual consciousness.

    I would also like to quote few lines from Hidayatnama from Sar Bachan (Poetry) by August Founder of Radhasoami Faith His Holiness Soamiji Mahraj.

    “When your eye turns inward in the brain and you see the firmament within, and your spirit leaves the body and rises upward, you will see the Akash in which is located Sahas-dal-kanwal, the thousand petals of which perform the various functions pertaining to the three worlds. …….At the apex of this Akash, there is a passage which is very small like the eye of a needle. Your Surat (spirit) should penetrate this eye. Further on, there is Banknal, the crooked path, which goes straight and then downward and again upwards. Beyond this passage comes the second stage.

    Trikuti (Region having three prominences) is situated here. It is one Lakhi Yojan2 in length and one Lakh Yojan in width. There are numerous varieties of glories and spectacles at that plane which are difficult to describe. Thousands of suns and moons look pale in comparison to the light there. All the time, melodious sounds of Ong Ong and Hoo Hoo, and the sounds resembling thunder of clouds, reverberate there. On attaining this region, the spirit becomes very happy, and purified and subtle.

    From here onward, it becomes cognizant of the spiritual regions. “

    Quantum theory can also not be applied in Pure Spiritual Region which was created before the first Big Bang where Time and Space does not exist. Nothing can be assumed of this Region.

    There is no Brain-Realization, there’s Self-Realization. Brain cannot know itself. Brain can know only surroundings. Soul or Spirit can know Itself and its surrounding. Know thyself is for God-Realization. ‘Apni khudi ko jo jana usne khuda ko pehchana’ (those who know themselves, recognize God).”

    1. Flora Light

      Thank you for this beautiful remark which clearified and explained for me very well some of the states of elevated (or spiritual) consciousness – spontaneously experienced by me over the past decades :))

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  5. Pingback: Mystery of human consciousness illuminated: Primitive consciousness emerges first as you awaken from anesthesia « Talesfromthelou's Blog

  6. I’d like to hear from bloggers if they can recall the epithany moment, the sudden realization or comprehension of themselves as living, being, seperate and distinct entities – ie “a person.”
    At what age did this occur? Do you remember where you were or what you had been doing immediately prior to this “awakening” experience? Was it a religious, pseudo-religious or spiritual experience? What did you feel? Were you surprised? Did you smile? Did you ever tell anyone?

  7. Pingback: How electrical brain stimulation can change the way we think — State of Globe

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