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Scientists explore consciousness

19.02.2008
Research into ‘one of the major scientific challenges to be solved’
New results published in the Proceedings of the National Academy of Sciences

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, signalling 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 Quiroga’s 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 Quiroga’s 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.

For more information contact:

Rodrigo Quian Quiroga
Reader in Bioengineering
Department of Engineering, University of Leicester
LE1 7RH Leicester, United Kingdom
Tel / Fax: +44 (0)116 252 2314 / 2619
email rqqg1@le.ac.uk
Issued by:

Ather Mirza
Press and Corporate Communications
Division of Marketing and Communications
University of Leicester
University Road
Leicester
LE1 7RH
tel: 0116 252 3335
email: pressoffice@le.ac.uk

UNIVERSITY OF LEICESTER
- A member of the 1994 Group of universities that share a commitment to research excellence, high quality teaching and an outstanding student experience.
Ranked top for student satisfaction in England (jointly with Oxford) among mainstream universities (average score of 4.4 out of 5 for overall satisfaction)
Ranked as a Top 20 university by The Sunday Times University Guide, The Guardian University Guide and the UK Good University Guide

One of just 23 UK universities to feature in world’s top 200- Shanghai Jiao Tong International Index, 2005-07.

Ranked in top 200 world universities by the THES (Times Higher Education Supplement)

Short listed University of the Year in 2007 by The Sunday Times and Short listed Higher Education Institution of the Year - THES awards 2005 and 2006
Ranked top 10 in England for research impact by The Guardian
Students’ Union of the Year award 2005, short listed 2006 and 2007
Founded in 1921, the University of Leicester has 19,000 students from 136 countries. Teaching in 18 subject areas has been graded Excellent by the Quality Assurance Agency- including 14 successive scores - a consistent run of success matched by just one other UK University. Leicester is world renowned for the invention of DNA Fingerprinting by Professor Sir Alec Jeffreys and houses Europe's biggest academic Space Research Centre. 90% of staff are actively engaged in high quality research and 13 subject areas have been awarded the highest rating of 5* and 5 for research quality, demonstrating excellence at an international level. The University's research grant income places it among the top 20 UK research universities. The University employs over 3,000 people, has an annual turnover of £184m, covers an estate of 94 hectares and is engaged in a £300m investment programme- among the biggest of any UK university.

Ather Mirza | University of Leicester
Further information:
http://www.le.ac.uk/neuroengineering
http://www.le.ac.uk/press/experts/intro.html

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