From: UFO UpDates - Toronto <ufoupdates.nul>
Date: Fri, 26 Dec 2008 10:04:45 -0500
Archived: Fri, 26 Dec 2008 10:04:45 -0500
Subject: The Brain's Subconscious Visual Sense




The lead to the article below came from 'The Norm',
who included this in his e-mail:

"Perhaps this article has some relevance to abductees recalling
details of their traumatic experience under hypnosis.

People who are allegedly abducted and have their conscious
memories of the event blocked out by their alien abductors (via
chemcial agents or something else) might later be able to
retrieve relevant information about the abduction experience
(under hypnosis) that had been subconsciously processed (via
bio-evolutionary "primitive" neural mechanisms) during the
abduction episode. This is pure conjecture. "

-----


Source: The New York Times - New York, USA

http://www.nytimes.com/2008/12/23/health/23blin.html?_r=3D2

December 22, 2008

[Several links in article


Blind, Yet Seeing: The Brain's Subconscious Visual Sense

By Benedict Carey
Published: December 22, 2008

The man, a doctor left blind by two successive strokes, refused
to take part in the experiment. He could not see anything, he
said, and had no interest in navigating an obstacle course - a
cluttered hallway - for the benefit of science. Why bother?

When he finally tried it, though, something remarkable happened.
He zigzagged down the hall, sidestepping a garbage can, a
tripod, a stack of paper and several boxes as if he could see
everything clearly. A researcher shadowed him in case he
stumbled.

"You just had to see it to believe it," said Beatrice de Gelder,
a neuroscientist at Harvard and Tilburg University in the
Netherlands, who with an international team of brain researchers
reported on the patient on Monday in the journal Current
Biology. A video is online at:

www.beatricedegelder.com/books.html

The study, which included extensive brain imaging, is the most
dramatic demonstration to date of so-called blindsight, the
native ability to sense things using the brain's primitive,
subcortical - and entirely subconscious - visual system.

Scientists have previously reported cases of blindsight in
people with partial damage to their visual lobes. The new report
is the first to show it in a person whose visual lobes - one in
each hemisphere, under the skull at the back of the head - were
completely destroyed. The finding suggests that people with
similar injuries may be able to recover some crude visual sense
with practice.

"It's a very rigorously done report and the first demonstration
of this in someone with apparent total absence of a striate
cortex, the visual processing region," said Dr. Richard Held, an
emeritus professor of cognitive and brain science at the
Massachusetts Institute of Technology, who with Ernst P=F6ppel and
Douglas Frost wrote the first published account of blindsight in
a person, in 1973.

The man in the new study, an African living in Switzerland at
the time, suffered the two strokes in his 50s, weeks apart, and
was profoundly blind by any of the usual measures. Unlike people
suffering from eye injuries, or congenital blindness in which
the visual system develops abnormally, his brain was otherwise
healthy, as were his eyes, so he had the necessary tools to
process subconscious vision. What he lacked were the circuits
that cobble together a clear, conscious picture.

The research team took brain scans and magnetic resonance images
to see the damage, finding no evidence of visual activity in the
cortex. They also found no evidence that the patient was
navigating by echolocation, the way that bats do. Both the
patient, T. N., and the researcher shadowing him walked the
course in silence.

The man himself was as dumbfounded as anyone that he was able to
navigate the obstacle course.

"The more educated people are," Dr. de Gelder said, "in my
experience, the less likely they are to believe they have these
resources that they are not aware of to avoid obstacles. And
this was a very educated person."

Scientists have long known that the brain digests what comes
through the eyes using two sets of circuits. Cells in the retina
project not only to the visual cortex - the destroyed regions in
this man - but also to subcortical areas, which in T. N. were
intact. These include the superior colliculus, which is crucial
in eye movements and may have other sensory functions; and,
probably, circuits running through the amygdala, which registers
emotion.

In an earlier experiment, one of the authors of the new paper,
Dr. Alan Pegna of Geneva University Hospitals, found that the
same African doctor had emotional blindsight. When presented
with images of fearful faces, he cringed subconsciously in the
same way that almost everyone does, even though he could not
consciously see the faces. The subcortical, primitive visual
system apparently registers not only solid objects but also
strong social signals.

Dr. Held, the M.I.T. neuroscientist, said that in lower mammals
these midbrain systems appeared to play a much larger role in
perception. In a study of rats published in the journal Science
last Friday, researchers demonstrated that cells deep in the
brain were in fact specialized to register certain qualities of
the environment.

They include place cells, which fire when an animal passes a
certain landmark, and head-direction cells, which track which
way the face is pointing. But the new study also found strong
evidence of what the scientists, from the Norwegian University
of Science and Technology in Trondheim, called "border cells,"
which fire when an animal is close to a wall or boundary of some
kind.

All of these types of neurons, which exist in some form in
humans, may too have assisted T. N. in his navigation of the
obstacle course.

In time, and with practice, people with brain injuries may learn
to lean more heavily on such subconscious or semiconscious
systems, and perhaps even begin to construct some conscious
vision from them.

"It's not clear how sharp it would be," Dr. Held said. "Probably
a vague, low-resolution spatial sense. But it might allow them
to move around more independently."



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