>>
http://news.yahoo.com/s/livescience/20080818/sc_livescience/scientistssaywecanseesound...
>> Scientists Say We Can See Sound
>> by Robin Nixon
>> Special to LiveScience
>>
LiveScience.com
>>
>> Turning conventional neuroscience on its head, new research suggests the
>> human
>> visual system processes sound and helps us see.
>>
>> Here's the basics of what was Neuroscience 101: The auditory system
>> records
>> sound, while the visual system focuses, well, on the visuals, and never
>> do they
>> meet. Instead, a "higher cognitive" producer, like the brain's superior
>> colliculus, uses these separate inputs to create our cinematic
>> experiences.
>>
>> The textbook rewrite: The brain can, if it must, directly use sound to
>> see and
>> light to hear.
>>
>> The study was published last week in the journal BMC Neuroscience.
>>
>> Monkey hear, monkey see
>>
>> Researchers trained monkeys to locate a light flashed on a screen. When
>> the
>> light was very bright, they easily found it; when it was dim, it took a
>> long
>> time. But if a dim light made a brief sound, the monkeys found it in no
>> time -
>> too quickly, in fact, than can be explained by the old theories.
>>
>> Recordings from 49 neurons responsible for the earliest stages of visual
>> processing, researchers found activation that mirrored the behavior. That
>> is,
>> when the sound was played, the neurons reacted as if there had been a
>> stronger
>> light, at a speed that can only be explained by a direct connection
>> between the
>> ear and eye brain regions, said researcher Ye Wang of the University of
>> Texas in
>> Houston.
>>
>> The study presents the first evidence that a sensory cell can process an
>> alternative sensation, said head researcher Pascal Barone of the
>> Universite Paul
>> Sabatier in Toulouse, France, who discovered a contender for the
>> anatomical
>> connection in 2002.
>>
>> Emergency broadcast
>>
>> The discovery likely explains the tremendously quick reactions of most
>> animals,
>> including humans, to stimuli that cue multiple senses, such as a rustling
>> tiger
>> or a honking bus.
>>
>> Especially in the corners of the visual field, where eyesight is poor,
>> the ears
>> take up the slack and stimulate the visual system, Barone said.
>>
>> An extra benefit, Wang explained, is the early visual system's spatial
>> precision, something higher brain regions fudge in favor of prioritizing
>> our
>> central gaze. By sending sound inputs directly to our image processor,
>> the
>> auditory system can avoid playing telephone with time-sensitive
>> information.
>>
>> Extra-sensory power
>>
>> The discovery is likely unrelated to the rare experience of synesthesia,
>> a
>> bizarre condition experienced by a few people who can feel, here and
>> taste
>> colors. In synesthesia, for example, more complicated sensations combine
>> at
>> later stages of brain processing, so that just the mention of a color, a
>> letter
>> or a shape can automatically trigger the perception of a certain note.
>>
>> What most excites Barone about the new findings is the potential for
>> "cortical
>> plasticity" in sensory areas.
>>
>> For example, the blind, by definition, do not use the visual system to
>> see. But
>> they can, this research suggests, use it to hear. This may explain how
>> blind
>> people develop such advanced hearing skills and, similarly, why the deaf
>> often
>> possess superior sight, said Barone.
>>
>> The primary visual system is also directly activated by touch - perhaps
>> helping
>> us slap that mosquito before it stings.
>> --
>> Frederick Martin McNeill
>> Poway, California, United States of America
>> mmcneill@
fuzzysys.com
>> ******************************************
>> "I never cease being dumbfounded by the unbelievable things people
>> believe."
>> - Leo Rosten
>> ******************************************
