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Newsletter 19

Hi,

Anatomy & Function - Which Comes First?

At CVI Scotland we love sharing publications with you, for many reasons, but the main reason is because some are really exciting. One area we find especially interesting, have written about quite a bit and shared several publications on, is blindsight.

We all have blindsight, but it is a non-conscious reflex, and whilst it can't be controlled, with a little practice it can be identified when it happens. For those who drive, when someone suddenly pulls out from a side road, possibly hoping you will stop and let them out, your reaction, whether it was to brake, honk your horn or look (or all three!) would have been triggered by your blindsight, which would have processed the scene and identified a threat, and triggered your reactions, faster than your conscious vision and mind could. Your conscious vision is still pretty fast, and the difference between conscious vision and blindsight is likely less than a second in most circumstances, but blindsight is faster. For non-drivers, just being somewhere busy like walking through a mall, someone might dash past you, making you jump or startle, or pull your arms towards yourself. Maybe walking through the woods, you might blink to prevent a twig going into your eye before you've even seen it. All of these reactions are triggered by your blindsight, protecting its master.

That is typical blindsight assisting a person who sees typically, but blindsight seems to have a capacity to function and even evolve where the visual brain is affected and not working so well. In some people perception of movement, in an area of vision that does not see things that are still, can even become conscious. George Riddoch (1842-1919) first reported this in his paper 'Dissociation of visual perceptions due to occipital injuries, with especial reference to appreciation of movement', published in 1917 - over a hundred years ago! How did he spot it? Because the visual function of his patients did not match their anatomy. Very simply, they could definitely see when they should not have been able to see (anatomically).

The case of 'The blind woman who could see rain' (links below) is another example of function not matching anatomy, where a woman who had no vision after a brain injury, sometime later became aware of seeing rain drops running down a window, despite not being able to see the still scene through the window. At first, she thought it must be some sort of distant visual memory - because the anatomy dictated she couldn't see - but she could (and was prescribed a rocking chair to help her to start to make use of this vision!).

And so we reach a sort of chicken and egg position, when thinking of the relationship between anatomy and function. Should the starting point be anatomy and from that should we consider what is 'known' to be possible, and impossible? Or should we start with function and look back towards the anatomy and think 'how on earth can they do that?' as we imagine George Riddoch must have thought over a hundred years ago.

We see anatomy and function like a close brother and sister, who fight but ultimately need each other. Anatomy is careful and measured and evidenced - he is the sensible one. Function is carefree, wild and refuses to be contained, and she continues to amaze with what she can do. When it comes to supporting those affected by CVI, we need both. We need to understand what has been sensibly and well researched and reported, whilst keeping an open mind as to what might be possible, including things that seem impossible, like blind people who can see.

A new paper we feature is about a girl who lost the vision on her right side (right homonymous hemianopia) following a brain injury. All the cases we have previously reported involved the brain finding a way on its own (links to papers below). This case was different though, the patient deliberately set out to develop her blindsight and try to shift it into conscious vision, through exercises, and succeeded in improving her functional vision! A bit like function saying to anatomy 'right, I'll show you!'.

This is anatomy and function together in a beautiful dance, one creating new pathways and the other exploring the unknown, seemingly without limits.

Like the brother and sister team of function and anatomy, we are carefully very excited about the possibilities.

Best wishes

The CVI Scotland Team

PS Everything new can be found in our Updates section, and via Twitter @scotlandcvi and our Facebook page.

In this issue...

  • Hemianopia (New Vision In Absent Visual Field) Paper
  • Blindsight Newspaper Feature
  • The Blind Woman Who Saw Rain (film)
  • Child with 'More Than Blindsight' Paper
  • CVI Film (from Holland)

Hemianopia (New Vision In Absent Visual Field) Paper

Introduction to paper explaining how a woman, through exercise and 'personal endeavour' evolved her blindsight to conscious vision.

Blindsight Newspaper Feature

Another look at the incredible case of the blind woman who could see rain (film below).

The Blind Woman Who Saw Rain (film)

This was the first film we ever posted on our website, fascinating and brilliant!

Child with 'More Than Blindsight' Paper

Featured before, but so important in understanding the extraordinary capacity of the brain.

CVI Film (from Holland)

A great 9 minute film with English subtitles, explaining both the experience and challenges of CVI through the world of three young people.

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About Us

At CVI Scotland we are devoted to helping people understand cerebral visual impairments, and together working towards developing the understanding of this complex condition.