[blindza] Re: Fw: Konekt blog - Emotional machines: and the blind could see
- From: toni kruger <freeflyflow@xxxxxxxxx>
- To: blindza@xxxxxxxxxxxxx
- Date: Thu, 17 Mar 2011 10:45:19 +0200
That's fascinating, Jake, all the stuff about how the brain processes
signals.
Toni Kruger
freeflyflow.design
Cell: +27 83 387 0815
www.freeflyflowdesign.co.za
A member of: www.consultwomen.co.za
"Our listening creates a sanctuary for the homeless parts within another
person."
Rachel Naomi Remen
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Makes you want to move your dancing feet..."
Marley - "Sun is shining"
On Wed, Mar 16, 2011 at 6:31 PM, Jacob Kruger <jacobk@xxxxxxxxxxxxxx> wrote:
> ----- Original Message ----- Konekt blog - Emotional machines: and the
> blind could see.
>
> Jeff Fraser.
>
> 03/15/2011 – TVSS stands for Tactile Visual Sensory Substitution, an
> assistive
> technology pioneered by Paul Bach-y-Rita in the seventies to help blind
> persons
> sense and react to their physical environment. Although at the time the
> technology wasn’t capable of resolution beyond a measly 20×20 cells, what
> it
> taught us about the brain is that prosthetics are not only feasible,
> they’re a
> lot closer to our reach than one might expect.
>
> With the processing power we now have at our disposal, we could be seeing
> an
> elegant, noninvasive visual prosthesis for the blind within a couple of
> decades.
>
> TVSS is based on a similar principle as a walking cane or what’s known as
> the
> “facial vision” of the blind. Certain blind persons report a light touch on
> the
> forehead or cheeks, as if being brushed with a veil, when encountering
> large
> objects within 30cm-80cm from the face, and can reliably identify the
> objects
> causing it.
>
> When discovered in the late nineteenth century, facial vision was thought
> to be
> a kind of extrasensory perception; now, thanks to the work of Dallenbach et
> al.
> (1944), we know that facial vision isn’t tactile at all – it’s auditory.
> Facial
> vision is based on the ability to detect the intensity and direction of
> reflected sounds. Astonishingly, one researcher (Kohler 1967) went so far
> as to
> anesthetize subjects’ faces – and discovered that they still felt facial
> vision
> occurring in their cheeks or forehead!
>
> The TVSS system works like this: a sensor placed somewhere on the person’s
> face,
> for instance in a pair of glasses, maps the intensity of incident light.
> The
> sensor’s electrical output is then translated into a set of regular
> instructions
> for a tactile stimulation device – a pad about 8″ square that can be worn
> on the
> back, stomach, or forehead. The pad massages the skin in an analogue of the
> light hitting the sensor. The hope is that, just like auditory signals
> being
> transformed into feelings of touch in facial vision, here tactile signals
> will
> be transformed into something like sight.
>
> It’s so simple, you wouldn’t think it could work. But it does.
>
> With practice, wearers become adept at using the system to locate, react
> to, and
> manipulate objects in space. Regardless of where the pad is placed on the
> body,
> eventually the wearer comes to orient the sensation toward the space being
> sensed, so that, rather than having to actively “interpret” the incoming
> tactile
> signals, they can respond to the TVSS similar to a person responding to
> sight.
>
> In a telling anecdote given by Bach-y-Rita, a subject accidentally
> magnified the
> zoom on his camera, causing the object before him to suddenly “loom”
> bigger. The
> subject jumped backwards in surprise – despite the fact that the tactile
> stimulator was on his back.
>
> Some wearers report a vaguely vision-like sense of where things are in the
> room.
> (The “vagueness” here is usually explained as an effect of the system’s
> poor
> resolution – the original system was effectively colorblind, stereoblind,
> and
> incredibly myopic.) Even more interesting is the fact that once trained
> with the
> TVSS, a pad can be placed on any sensitive region of the body – even
> distributed
> in a metric-preserving way – without loss of aptitude. It’s as if the brain
> has
> learned to treat the TVSS as an extension of the sensory nervous system.
>
> What’s the explanation? It’s all about brain plasticity.
>
> Typically, blind persons have not lost the cortical regions that enable
> them to
> see, but only the retinal synapses that connect their eyes to their brain.
> Recent neuroimaging studies using PET and fMRI have shown that during
> tactile
> visual substitution, blind subjects recruit extra-striate occipital areas
> thought to be involved with visual processing.
>
> A Trans-Cranial Magnetic Stimulation (TMS) study, which simulated lesions
> in
> these areas, disrupted blind but not sighted blindfolded controls in
> performing
> a depth-perception task. All of the studies found that activation of the
> occipital areas was minimal upon introduction to the substitution system,
> but
> increased with training. Cheers to the brain that changes itself.
>
> On the other hand, brain plasticity can’t explain everything. The brain
> doesn’t
> need to be induced to transfer tactile stimulation to the visual processing
> areas – it does this automatically. How does the brain know that TVSS
> stimulation should be processed as sight, rather than some other perceptual
> modality? One possible explanation is that we use the same “mental imagery”
> apparatus to “picture” the unseen stimulus; however this fails to explain
> why
> blindfolded sighted controls show less activation in the same areas.
>
> If you read my last post, you may have guessed where this is going:
> sensorimotor
> contingencies.
>
> O’Regan and Noe (who are quickly becoming my heroes) have used TVSS as a
> foundational argument for their theory that sight is not just about where
> stimulus gets processed, but about the nature of the signal itself. TVSS is
> vision-like, in the sense that it responds in regular ways to the subject’s
> movements and associated changes in hearing and proprioception. The brain
> is
> able to tell that TVSS stimulation needs to be routed to visual centres
> because
> it bears distinctly “visual” relations to the rest of the sensorimotor
> system.
>
> As a final note, it’s worth pointing out that the strangeness of TVSS isn’t
> really all that unusual, if you consider the fact that when someone pokes
> your
> arm, you feel it in your arm – despite the fact that the sensory
> information is
> being processed in your brain. The fact that you hear at your ears, see at
> your
> eyes, and feel at your skin doesn’t have anything to do with where your
> sensory
> nerves are placed; it has to do with the way your brain projects perception
> onto
> your body.
>
> In just the same way, this kind of perceptual projection accounts for all
> sorts
> of strange phenomena – like sympathetic or remote tactile sensing, in which
> a
> subject feels an experimenter touch the arm of a mannequin as if it were
> her own
> arm. Another experiment showed that a subject can be “tricked” into feeling
> a
> touch on her index finger when the experimenter is actually poking her
> middle
> finger.
>
> The practical upshot of all this is that we don’t need to find the
> specifically
> “visual” neural submodule in the brain or nervous system in order to create
> sensory prostheses – we cam simply throw signals at the nervous system
> through
> auditory or tactile channels, and let brain plasticity do all the real
> work.
>
> If this interpretation of the research stands up, then given ten years and
> enough research dollars, sensory handicaps could be a thing of the past.
>
> To leave off with a promising example, researcher Kevin Warwick, aka
> “Captain
> Cyborg,” has shown that a form of sensory substitution can be interfaced
> directly with the human nervous system. In 2002, he had a chip implanted in
> his
> arm that allowed him to feel stimulation of a robotic hand and move it as
> if it
> was his own. This video presents some of his ideas on how cybernetic
> prostheses
> could change our future.
>
> Source URL:
> http://www.konekt.ca/blog/emotional-machines-athe-blind-could-see
>
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