Those were the days of stenographers and typists, and manual typewriters
at every office. And there used to be competitions for speed-typing. Our
stenographer at Centre for Cellular and Molecular Biology, the late Mr.
Ramarao, was a champion, typing away at break-neck speed. Well, those days are
gone. Most of us today are our own typists, touching away text message and
emails at our PCs or tablets, or gripping the Smartphone with the right palm
and using the right thumb with great rapidity. Not everyone has a touch-screen
phone. Many still use the old-fashioned ones, where you have to push buttons
for each letter or number. The way the two grip the phones and enter the
characters is quite different. How then do their touch-sensitive (tactile)
areas of the brain differ from those of the touch-screen-wallas? Just as what
we see is captured and processed in the brain by the visual cortex, the region
called the somatosensory cortex receives and responds to tactile signals. This
question of the difference between those who use touch-screen devices and those
who are still ‘classical’ has attracted the attention Dr. Arko Ghosh and
colleagues at the University of Zurich, Switzerland. They note that
touch-screen phone screens demand repetitive finger movements. But whether and
how the somatosensory cortex conforms to this is not known. To this end, they
analysed how the cortical processing of signals coming from fingertips in
touch-screen phone users differs from ones from those using traditional
old-fashioned phones.
How the brain registers and reacts was monitored by placing a
tight-fitting skullcap with over 62 surface electrodes distributed over the
entire scalp. This helped detect the electrical signals evoked by touch on the
thumb, index and middle fingers of the right hand. (Note that the phone is
grabbed by the entire palm, with the first three fingers clutching it, while
the thumb touches the various letters and numbers.) Thirty-seven right-handed
volunteers were analysed, of whom 26 had touch screen phones and 11 had old
technology mobile phones.
Several results came out. One was that the touch-screen phone users
spent far more than with their phones than did the non-users. And they relied
mostly on their thumbs to interact with the screen. Yet, the electrical
potentials recorded on the somatosensory cortex associated with the first three
fingertips were higher than those in non-users.
Is this because of a more intense use of the hand or due to greater
“skill” to touch than to push the buttons in the old technology by mobile
phones? To check this, the researchers looked into the time used by the
batteries of the phones and found that the cortical signals were directly
proportional to how much each person used his or her phone. The more they used
the thumb, the greater this signal.
But does practice make perfect, like what is seen in, say, musicians?
Apparently not. The thumb signal measurements fluctuated. The greatest response
was seen when the telephone was most recently used; it was not a linear or
cumulative build-up as with musicians, but depended on recent use. Musicians
start an early age, and go through disciplined practice. For touch-screen phone
users, if appears more like a “temporary reallocation of neuronal resources.”
The price you pay
Alas, the downside for Ramarao was recurrent pain in his right forearm
and wrist. Doctors call this the Carpal Tunnel syndrome, a muscular fatigue and
consistent pain resulting from an excessive use of the wrist and fingers. He
had to be rested often and given painkillers and physiotherapy. His speed came
at a cost.
The modern day avatar of this is seen in youngsters. Researches at the
University of Waterloo, Canada, studied 140 university students and found 84
per cent of them had pain in at least one part of the body related to the time
spent on browsing the Internet; and with the touch-screen phone users, the pain
was most common in the thumb. And Hazel Parry, in her article “The curse of
iPhone” in China Daily of Hong Kong, points out that many constant users
who arch down their necks to read their touch-screen phone screens suffer from
bad posture, and pain in the wrist and neck (called Tech-neck) and “Blackberry
Thumb.” The worst is to use smart phones while travelling in subways and local
trains. This affects your balance and eyesight as well; Parry compares
Tech-neck with Tennis Elbow or Washerwomen’s Sprain.
Ghosh and colleagues propose in their above paper (published in Current
Biology, on January 5, 2015) that “cortical sensory processing in the
contemporary brain is continuously shaped by the use of personal digital
technology”. Well, not only sensory processing but sensory pain as well.
Source | The Hindu | 2 August 2015
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