the last frontier of sense science (Wired UK)


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Touch, says David J.
Linden
, is something we take for granted. “It’s very hard to
imagine it gone,” he tells WIRED.co.uk. “You can imagine what it’s
like to be blind or deaf, or have no sense of smell, but there’s no
way to turn off touch”.

Touch might not be an obvious starting point for
Linden, who is a professor of neuroscience at the John Hopkins
University, studying learning and memory. But according to the
professor, “the story of the neuroscience underlying touch has yet
to be told”. Pointing to the advances made in touch research over
the last 20 years, Linden tells us that his own interest in the
topic was sparked over lunch by colleagues working in the School of
Medicine. 

Making the complex links between the brain and our
sense of touch accessible to a wider audience is no easy feat. Yet
in his recent book entitled, Touch: The Science of Hand, Heart,
and Mind
, Linden offers anecdotal and factual ways in to
exploring different aspects of touch, whether that be in the form
of pain, itches, hot and cold sensations or caresses.

“We think of touch as being a one sense modality, but
it’s many different sensors in the skin acting in parallel,” says
Linden. He explains how the information in the form of, for
example, an itch, pain or caress relays to the brain, dividing them
into either discriminative or emotional forms of touch.

The discriminative touch allows a person to understand
where the body is being touched, or to understand if an object is
textured, smooth or 3D. While emotional touch is what makes pain
feel emotionally negative, or an orgasm feel positive, says
Linden.

“We think of touch sensation as being a default. We
don’t associate fact with emotion, but though computed differently,
they are blended together,” he says. This, however, is only
revealed when either the discriminative or emotional relays are
damaged. “If you damage the sensory cortex, then you lose the
ability to decode the factual abilities of touch. If you damage the
emotional touch region of the brain, you will lose the ability to
decipher emotional touch”.

Touch also plays a dramatic role for infants. “If you
don’t receive loving touch as a toddler, at the age of two, you
will have attachment disorders, mental retardation, physical,
immune and digestive problems,” says Linden, who refers to an
understaffed orphanage in Romania, where lack of tactile
interactions negatively impacted children. He adds, however, that
interventions of even 38 minutes can prevent such damaging
effects.


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Interpersonal touch also acts as a social glue,
binding families, sexual partners, and where appropriate fosters
emotions of cooperation, gratitude and trust among colleagues, says
Linden. But outlawing touch in offices and schools, he says, can
often lead to unintended consequences. “Regulations on touching in
schools and workplaces come from good motivations as you don’t want
predators to be encouraged,” says Linden, who points, however, that
predators will ignore such rules. “In most government-funded
schools teachers are prevented from touching kids when they’re
upset. They [teachers] must run away, and this makes children feel
bad”.

While Linden explores the repercussions of touch deprivation in
his book, he also tells us of his particular interest in the more
carnal sides of touch. “Sexual sensation is so important, we spend
so much energy thinking about it, but we don’t understand how it
originates,” says Linden. “Embarrassingly for the field of biology, we know very little about the sensors
of the skin. If you wanted to know how taste originated, you’d
point to the taste buds in the tongue, for a banana smell, you’d
point to the gene that encodes the main odour of a banana. But for
sexual sensation, I can’t tell you the cells or the molecules,
which is astonishingly ignorant”.

Just last year, a team of researchers from¬†South Korea’s
Seoul National University conducted research on the possibility of
attaching
“smart skin” to prosthetics
. This aimed to reconfer a sense of
touch to those who had lost limbs, or received irreparable damage
to their skin. As surgical robots such as Da Vinci increasingly aid surgeons carry out operations
on patients, the idea of incorporating haptics with robotics comes
increasingly to the fore.

“Right now people are working hard to integrate haptics into
robots working autonomously, as well as a robotic arm used by a
robot,” says Linden. “But right now, if you use a robot arm, you
don’t have feedback from that tool when you use it”.

When humans play a violin, the sensors in our fingertips allow
us to sense the vibrations, or when you plunge a shovel into the
sand, you can tell from the vibrations whether you are digging sand
or soil, explains Linden. “Those sensations are lacking from human
controlled and autonomous sensors,” says Linden. “Right now, what
people are trying to build is only the factual system of touch, I’m
not aware of a robot which has the emotional touch system”.

Touch:
The Science of Hand, Heart and Mind is out now

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20 March 2015 | 4:11 pm – Source: wired.co.uk

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