Blindsight: How brain sees what you do not see

Oct 14, 2008

Blindsight is a phenomenon in which patients with damage in the primary visual cortex of the brain can tell where an object is although they claim they cannot see it. A research team led by Prof. Tadashi Isa and Dr. Masatoshi Yoshida of the National Institute for Physiological Sciences, Japan, provides compelling evidence that blindsight occurs because visual information is conveyed bypassing the primary visual cortex. Japan Science and Technology Agency supported this study. The team reports their finding in the Journal of Neuroscience on Oct 15, 2008.

The researchers recorded eye movements of Japanese monkeys that had damage in one side of the primary visual cortex. Training with an eye movement task for 2-3 months enabled the monkeys to move their eyes to the correct direction where an object was even in the affected side of their visual fields. Brain became able to feel where an object was without 'seeing' it. After the training, their eye movements looked almost normal; they discriminated five different directions even in the affected visual field.

To investigate how eyes move, the monkeys' eye movements to targets in their affected visual field were compared with those to dark targets in their normal visual field. Both were 'equally difficult to see'. By this trick, the researchers found two differences from the normal: 1) the trajectory of their eye movements was straight and 2) the response time of their eye movement was short. These differences were thought to be due to the damage of eye movement control and decision making, not purely on that of vision. Therefore, the researchers concluded that the monkeys' eye movements after damage in the primary visual cortex were mediated by a qualitatively different vision which is supported by alternative brain circuits bypassing the primary visual cortex.

"Our finding will provide a new strategy for rehabilitation of these patients with damage in the primary visual cortex. That will be a rehabilitation training to activate alternative brain circuits to see what you do not see", said Dr. Yoshida. "A similar training may help the patients to know where an object is even without 'seeing' it."

Source: National Institute for Physiological Sciences

Explore further: Unprecedented germ diversity found in remote Amazonian tribe

Related Stories

Researchers identify new neurological deficit behind lazy eye

Sep 10, 2010

Researchers at New York University's Center for Neural Science have identified a new neurological deficit behind amblyopia, or "lazy eye." Their findings, which appear in the most recent issue of the Journal of Neuroscience, shed a ...

Mystery of funky "disco clam" flashing revealed

Jan 05, 2015

In the dark, underwater caves of the Indo-Pacific Ocean, a lucky diver may be treated to a rare underwater light show: the flashing of the clam Ctenoides ales, also known as the 'disco' clam. How and why ...

Recommended for you

Bacteria play only a minor role stomach ulcers in cattle

Apr 17, 2015

Scientists at the University of Veterinary Medicine Vienna investigated whether stomach ulcers in cattle are related to the presence of certain bacteria. For their study, they analysed bacteria present in ...

New research reveals how our skeleton is a lot like our brain

Apr 17, 2015

Researchers from Monash University and St Vincent's Institute of Medical Research in Melbourne have used mathematical modelling combined with advanced imaging technology to calculate, for the first time, the number and connectivity ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

gmurphy
5 / 5 (2) Oct 15, 2008
this isn't new research. This is a well known phenomenon in neural visual aphasias. It's not worth blinding a few monkeys for this. There are people who suffer from these conditions who could provide more accurate feedback to the researchers. I'm not against experimenting on animals when there's a real chance to learn something. But intentionally harming a cognizant animal simply to confirm what was already known has no justification.
holmstar
not rated yet Oct 15, 2008
this isn't new research. This is a well known phenomenon in neural visual aphasias. It's not worth blinding a few monkeys for this. There are people who suffer from these conditions who could provide more accurate feedback to the researchers. I'm not against experimenting on animals when there's a real chance to learn something. But intentionally harming a cognizant animal simply to confirm what was already known has no justification.


Seriously... this would be a non-invasive test for a human who already has the injury. What a waste of good monkeys. :-P
QubitTamer
not rated yet Oct 15, 2008
And what's not fun about blinding monkey? Have you ever taunted a blind monkey? They don't know where to throw the dung!!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.