Finnish scientist gets partially blind patient to see colours

Study awakens international interest

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A Finnish scientist and his colleagues at Britain’s Essex University have succeeded in restoring the ability to perceive colours to a partially blind patient.
     The study, by Juha Silvanto and his colleagues, was published on Tuesday, and has sparked interest around the world.
     
Silvanto and his team studied the case of a patient suffering from damage to the visual cortex in the brain.
     As a child, the patient had suffered an injury to the left side of the cortex in a car accident. The injury prevents signals that reach the brain from being passed on to the patient’s consciousness. Because of the injury, affecting the left side of the visual cortex, the patient is unable to see the right side of his field of vision at all.
     
Silvanto and his group stimulated the patient's visual cortex with a rapidly fluctuating magnetic field, which was created with a magnetic device placed close to the patient’s head.
     When colours were shown in the patient’s healthy field of vision, the patient saw glistening coloured stars in both the healthy and blind part of the field of vision.
     The result is seen as interesting, because all sensations of sight have been seen to be dependent on a healthy visual cortex.
     The results suggest that at least some sensations can be seen even if the area is damaged.
     Also significant was that the researchers were able to stimulate an experience of sight without going into the patient’s brain.
     The study, published in the journal Current Biology, has been quoted in a number of magazines, including New Scientist and Der Spiegel.
     
“The result was a big surprise for us as well. our starting point has been that this area is necessary for making observations”, Silvanto says.
     Silvanto says that brain damage of the kind that were under investigation is common among victims of strokes, for instance. He adds that there is still a long way to go before sight can actually be restored to those who have suffered such injuries.


Links:
  Current Biology - summary: Inducing conscious perception of colour in blindsight

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