You are currently browsing the thoughts on thoughts weblog archives for the day 21/01/2010.
| M | T | W | T | F | S | S |
|---|---|---|---|---|---|---|
| « Dec | Feb » | |||||
| 1 | 2 | 3 | ||||
| 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| 11 | 12 | 13 | 14 | 15 | 16 | 17 |
| 18 | 19 | 20 | 21 | 22 | 23 | 24 |
| 25 | 26 | 27 | 28 | 29 | 30 | 31 |
- 05/02/2012: Failure of conscious thought suppression
- 02/02/2012: What is the preconscious?
- 30/01/2012: Are there two types of cognition?
- 27/01/2012: The new way to view cognition
- 24/01/2012: About the claustrum
- 21/01/2012: Two sides of synchrony
- 18/01/2012: Skull shape changes are not independent
- 15/01/2012: the other way around
- 12/01/2012: A look at the dogma
- 09/01/2012: the Freud hangup
- February 2012
- January 2012
- December 2011
- November 2011
- October 2011
- September 2011
- August 2011
- July 2011
- June 2011
- May 2011
- April 2011
- March 2011
- February 2011
- January 2011
- December 2010
- November 2010
- October 2010
- September 2010
- August 2010
- July 2010
- June 2010
- May 2010
- April 2010
- March 2010
- February 2010
- January 2010
- December 2009
- November 2009
- October 2009
- September 2009
- August 2009
- July 2009
- June 2009
- May 2009
- April 2009
- March 2009
- February 2009
- January 2009
- December 2008
- November 2008
- October 2008
- September 2008
- August 2008
- July 2008
- June 2008
Archive for 21/01/2010
Ignition of consciousness
21/01/2010 by admin.
ScienceDaily has a report (here) on research by R. Malach, L. Fisch and I. Fried published in Neuron. They found an ‘ignition’ of intense neural activity associated with consciously seeing an image. They use a very powerful method (not available to everyone). Epileptic patients who have electrodes implanted in their brains in preparation for surgery are asked to volunteer of tests on perceptual awareness.
The subjects looked at a computer screen, which briefly presented a ‘target’ image… followed by a ‘mask’ … at different time intervals after the target image had been presented. This allowed the experimenter to control the visibility of the images — the patients sometimes recognized the targets and sometimes failed to do so. By comparing the electrode recordings to the patients’ reports of whether they had correctly recognized the image or not, the scientists were able to pinpoint when, where and what was happening in the brain as transitions in perceptual awareness took place.
Malach: ‘We found that there was a rapid burst of neural activity occurring in the high-order visual centers of the brain (centers that are sensitive to entire images of objects, such as faces) whenever patients had correctly recognized the target image.’ The scientists also found that the transition from not seeing to seeing happens abruptly. Fisch: ‘When the mask was presented too soon after the target image, it ‘killed’ the visual input signals, resulting in the patients being unable to recognize the object. The patients suddenly became consciously aware of the target image at a clear threshold, suggesting that the brain needs a specific amount of time to process the input signals in order for conscious perceptual awareness to be ‘ignited.”
This study is the first of its kind to uncover strong evidence linking ‘ignition’ of bursts of neural activity to perceptual awareness in humans. More questions remain: Is this the sole mechanism involved in the transition to perceptual awareness? To what extent is it a local phenomenon?
Posted in Uncategorized | 1 Comment »