Navigation Links
Scientists explore consciousness
Date:2/18/2008

An international team of scientists led by a University of Leicester researcher has carried out a scientific study into the realm of consciousness.

The scientists have made a significant step into the understanding of conscious perception, by showing how single neurons in the human brain reacted to perceived and nonperceived images.

University of Leicester bioengineer Dr Rodrigo Quian Quiroga is spearheading this study which is opening new possibilities of exploring a hitherto relatively unchartered scientific area.

The team have today (MONDAY FEB 18) published a paper in an international journal, the Proceedings of the National Academy of Sciences (PNAS) revealing new discoveries in the field of consciousness studies.

Dr Quian Quiroga said: There has been much interest in recent years in consciousness, which is considered by many as one of the major scientific challenges to be solved, or at least addressed in a scientific -rather than just philosophical- way.

In fact, there are a few centres, journals and conferences dedicated to this topic. The problem with consciousness is that it is very hard to be defined and it implicates too many different things. For this reason, several researchers started to specify more clearly what they mean by consciousness (even if this is a limited view of the whole issue) and think about ways to study it in a scientific way. This approach was championed by the late Francis Crick and my former supervisor at Caltech, Christof Koch.

Following this line, the paper in PNAS asks how the activity of single neurons in the human brain can reflect conscious perception.

Recordings were done in epileptic patients candidates of curative surgery in which intracranial electrodes are implanted to establish the location of the epileptic focus and evaluate the potential outcome of the surgery. Patients usually stay for 1 or 2 weeks in the guard and this gives us the extraordinary opportunity to perform experiments and study how neurons in the human brain respond to different perceptual and behavioural tasks.

In this particular study we showed pictures in a computer screen very briefly, at the threshold of conscious recognition. Subjects had to report whether they recognized or not the particular picture showed in each trial. The key point is that, since the pictures are shown very briefly, for exactly the same visual input sometimes the subjects reported recognizing the picture and sometimes not recognizing it. Then we could ask whether the neurons fire according to the subjects' conscious perception or the actual visual inputs.

We found that the neurons we recorded responded to the conscious perception in an "all-or-none" way by dramatically changing their firing rate only when the pictures were recognized.

For example, a neuron in the hippocampus of one patient fired very strongly to a picture of the patient's brother when recognized and remained completely silent when it was not, another neuron behaved in the same manner with pictures of the World Trade Centre, etc.

Interestingly, based on the firing of these neurons it was possible to predict far above chance whether a picture was recognized or not. Another interesting observation is that a picture flashed very briefly generated nearly the same response -if recognized- as when shown for much longer periods of time. This means that a single snapshot as brief as 33 ms was sufficient to trigger strong neuronal responses far outlasting the stimulus presentation, signaling the conscious perception of the picture shown.

Dr Quian Quiroga said the study had important implications. Potential applications of this discovery include the development of Neural Prosthetic devices to be used by paralysed patients or amputees. A patient with a lesion in the spinal cord (as with the late Christopher Reeves), can still think about reaching a cup of tea with his arm, but this order is not transmitted to the muscles.

The idea of Neural Prostheses is to read these commands directly from the brain and transmit them to bionic devices such as a robotic arm that the patient could control directly from the brain.

Dr Quian Quirogas work showing that it is possible to read signals from the brain is a good step forward in this direction. But there are still clinical and ethical issues that have to be resolved before Neural Prosthetic devices can be applied in humans.

In particular, these would involve invasive surgery, which would have to be justified by a clear improvement for the patient before it could be undertaken.

Dr Quian Quirogas discovery has far-reaching implications not only for the development of neuronal prostheses, but for treatment of patients with pathologies involving the hippocampal formation, such as epilepsy, Alzheimers and schizophrenia and for further understanding of how perceptions and memories are represented in the brain.


'/>"/>

Contact: Rodrigo Quian Quiroga
rqqg1@le.ac.uk
01-162-522-314
University of Leicester
Source:Eurekalert

Related medicine news :

1. Scientists using laser light to detect potential diseases via breath samples, says new study
2. Scientists move towards stem cell therapy trials to mend shattered bones
3. U-M scientists develop tool to probe role of oxidative stress in aging, disease
4. Scientists Show Stem Cells Dont Cause Cancer
5. Microbial cheaters help scientists ID social genes
6. Scientists solve structure of gene regulator that plays key role in cancer
7. VEGF Neutralization Can Damage Brain Vessels, Say Schepens Eye Research Institute Scientists
8. VEGF neutralization can damage brain vessels, say Schepens Eye Research Institute scientists
9. Precious Time - Scientists discover how long heart failure patients can expect to live
10. UCLA stem cell scientists reprogram human skin cells into embryonic stem cells
11. Scientists Reprogram Human Skin Cells Into Embryonic Stem Cells
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... The temporary closing of Bruton Memorial Library ... City Observer , brings up a new, often overlooked aspect of head lice: the parasite’s ... for fumigation is not a common occurrence, but a necessary one in the event that ...
(Date:6/25/2016)... , ... June 25, 2016 , ... ... and non-athletes recover from injury. Recently, he has implemented orthobiologic procedures as a ... area —Johnson is one of the first doctors to perform the treatment. Orthobiologics ...
(Date:6/24/2016)... ... June 24, 2016 , ... Those who have experienced traumatic events may ... to unhealthy avenues, such as drug or alcohol abuse, as a coping mechanism. To ... for healthy coping following a traumatic event. , Trauma sufferers tend to feel a ...
(Date:6/24/2016)... ... , ... Global law firm Greenberg Traurig, P.A. announced that 20 Florida attorneys ... peers for this recognition are considered among the top 2 percent of lawyers practicing ... members of this year’s Legal Elite Hall of Fame: Miami Shareholders Mark D. ...
(Date:6/24/2016)... ... 2016 , ... People across the U.S. are sharpening their pencils and honing ... contest in which patients and their families pay tribute to a genetic counselor by ... Society of Genetic Counselors (NSGC) Annual Education Conference (AEC) this September. , In ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... N.C. , June 24, 2016  Consumers ... decisions and regulators/payers have placed more emphasis on ... environment, patient support programs in the pharmaceutical industry ... patients, medications. Consequently, pharmaceutical companies are focusing on ... they are providing products and services that improve ...
(Date:6/24/2016)... June 24, 2016  Global Blood Therapeutics, Inc. (GBT) ... developing novel therapeutics for the treatment of grievous ... the closing of its previously announced underwritten public ... the public offering price of $18.75 per share. ... offered by GBT. GBT estimates net proceeds from ...
(Date:6/24/2016)... , June 24, 2016 ... has announced the addition of the " Global ... This report ... provides an updated review, including its applications in various ... total market, which includes three main industries: pharmaceutical and ...
Breaking Medicine Technology: