Navigation Links
Scientists solving the mystery of human consciousness
Date:4/4/2012

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.

"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?


'/>"/>

Contact: Dr. Harry Scheinin
harry.scheinin@utu.fi
358-400-825-599
Academy of Finland
Source:Eurekalert  

Related medicine news :

1. Scientists Pinpoint Area of Brain That Fears Losing Money
2. Scientists Discover How HIV Is Transmitted Between Men
3. Prevention Is Key Research Goal for Premature Babies, Scientists Say
4. Scientists Discover Molecular Pathway for Organ Tissue Regeneration and Repair
5. Scientists find donut-shaped structure of enzyme involved in energy metabolism
6. Neuroscientists reveal new links that regulate brain electrical activity
7. Two UCSF Scientists to Receive Prestigious Dementia Research Honor
8. Johns Hopkins scientists develop personalized blood tests for cancer using whole genome sequencing
9. Scientists Spot Genetic Fingerprints of Individual Cancers
10. Scientists Unravel Mysteries of Intelligence
11. MSU scientists develop more effective method of predicting lead-poisoning risk
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Scientists solving the mystery of human consciousness
(Date:12/8/2016)... ... December 08, 2016 , ... The West Virginia ... 1, 2017. The name change aligns the entire company with its existing ... care quality. , “We are very proud of the achievements associated with the ...
(Date:12/8/2016)... ... December 08, 2016 , ... After enjoying record-breaking attendance at ... for its 33rd Annual Issues & Research Conference, March 2-3, 2017, at ... the conference is “Persistent Challenges and New Opportunities: Using Research to Accelerate the ...
(Date:12/8/2016)... ... December 08, 2016 , ... ... “Natural Language Processing–Enabled and Conventional Data Capture Methods for Input to Electronic Health ... . , Results of the comparative usability study demonstrate that a dictation-based method ...
(Date:12/8/2016)... ... December 08, 2016 , ... Mirixa Corporation , a ... other pharmacist-delivered patient care services, has announced the promotions of Karen Litsinger to ... president of sales. , Litsinger joined Mirixa in 2008 after serving as ...
(Date:12/8/2016)... ... ... With the increasing demand for dental implants, the National Association of Dental ... dentists and patients about the safety issues related to dental restorations. According to the ... is projected to reach $6.4 billion in 2018 with more than 30 million Americans ...
Breaking Medicine News(10 mins):
(Date:12/8/2016)... QUEBEC CITY , Dec. 8, 2016 /PRNewswire/ ... key US patents for improving the accuracy, reproducibility ... CD images in long and small bone orthopaedic ... proprietary approach to creating personalized orthopaedic restorations based ... create personalized orthopaedic restorations, the company harnesses the ...
(Date:12/8/2016)...  A new study by a pair of Geisinger ... therapy to treat chronic pain is not only ineffective, ... consequences, including death. Palliative care physicians ... , M.D., authored the study which provides a review ... study was published in the December 2016 edition of ...
(Date:12/8/2016)... Information products and services provider Elsevier has launched ... world,s largest abstract and citation database of peer-reviewed literature, providing the ... 5,000 publishers. The new set of metrics will improve decisions on ... adjust a journal,s editorial strategy. ... , CiteScore metrics comprise ...
Breaking Medicine Technology: