Tag Archives: Visual Disorders

Colour-blindness a variation in visual perception ability possibly endowing advantages relevant to work performance, rather than simply a disability

Payne, Rob Colour-blindness may aid in search and rescue effort. Science Network. November 11th 2015.
http://www.sciencewa.net.au/topics/health-a-medicine/item/3902-colour-blindness-may-aid-in-search-and-rescue-efforts

The idea that colour-blindness can be advantagous is not new to me, as last year I watched with great interest a story on ABC24’s News Breakfast in which the colour-blind presenter Michael Rowland explained his advantage over people with normal colour vision in visually detecting camouflaged items. Unfortunately the clip of this story is no longer available to view.

Vision scientist explains colour blindness. ABC News Breakfast. 7 Apr 2014.

http://www.abc.net.au/news/2014-04-07/vision-scientist-explains-colour-blindness/5371294

 

Time-blind, face-blind, smell-impaired, touch-disabled, dyslexic – there’s an amazing variety of disabilities of perception

It goes to show how common synaesthesia is, when a host of a radio show episode about super-recognition that I have referred to previously at this blog just happens to be a synaesthete. I know this because she was on the radio yesterday morning promoting her latest pop psychology book, which looks like it will be an interesting read. The BBC broadcaster, author and psychologist Claudia Hammond experiences the days of the week as having their own colours and insists that Monday is a pillar-box red, an assertion which to my mind does not seem odd but simply incorrect. Sure enough, the letter M is red (but certainly not pillar-box red) but surely it is plain to anyone that Mondays are white? Hammond and the cheery radio show host Natasha Mitchell also discussed other varieties of synaesthesia: time-space synaesthesia and mental number lines. Hammond’s new book is about the perception of time and it looks like it will include discussion of disability in perceiving time, and will also probably cover time-space synaesthesia.

I’ve had a look on the internet for more info about Hammond’s new book titled Time Warped, and while reading an excerpt of the book at Amazon I’ve found yet another obscure and highly specialized type of disability of perception, an inability to sense the passing of time, a condition which appears to be so obscure that it still has no name. Hammond gives a fascinating description of Eleanor, who has a deficit in sensing the passing of time that goes way beyond poor time management skills, and also has dyslexia, probably not coincidentally.

In this blog which is primarily about exploring possible links between synaesthesia and high ability in face perception and also an exploration of the opposite condition of prosopagnosia or face-blindness, I have discovered that prosopagnosia is by no means the only highly specialized disability of perception. Prosopagnosia is only one of a range of visual agnosias, which is a sub-set of the agnosias, which are a huge range of brain-based diabilities (not associated with memory loss) in recognizing specific things such as people, voices, shapes, smells, time, faces, colours, classes of objects, images of objects, pain, speech, text, body language, intonation, etc. Prosopagnosia appears to be often associated with another agnosia which is a disability in establishing visual memories of scenes, including things like streetscapes and buildings, and it seems possible that it could be linked with other better-known disabilities such as dyslexia. Each case is different, and prosopagnosia and other agnosias can be caused by genetics or damage in the brain, so one should not make sweeping generalizations. There appears to be no standard term or definition of the issue with place memory, with a variety of terms in use. I guess most people would be aware of the sensory and perception disabilities of blindness, deafness, paralysis and dyslexia, but there is also a huge range of other specific disabilities and disorders of perception and understanding, some affecting taste, smell, balance, mathematical and number sense, touch, music and tone perception. Many of these can be naturally-occuring or the result of brain injury. New Scientist magazine reported a while ago that a deficit in the sense of touch appears to be genetically linked with deafness. Scientists are only now beginning to establish knowledge about the nature of these disabilities and possible relationships between them. On top of this bewildering range of agnosias and disabilities are sensory disorders and visual disturbances that can be asociated with mental illness or are similar to mental illness. And on top of that are sensory-cognitive experiences that are simply odd or unusual but not disordered or a deficit. Synaesthesia fits into this category, of which there are more types than any sensible person would claim to know.

I find these things endlessly fascinating because it gives an insight into the significant fact that there can be many important differences between the way that apparently normal, intelligent people percieve and understand what appear to be simple sensory inputs from the world around us. The more I study this subject, the more I understand that there is nothing simple about perception and the understanding of sensory inputs. This kind of brain-work is hugely complex and it is no wonder that many areas of the brain are involved in this kind of work, and that sensory processing is very much involved in thinking in general. It is impossible to guess how many different ways that the person sitting next to you on the train might differ from you in perception and sensing, and it isn’t only about disability. For many of the agnosias and diabilities of perception and sensing there are conditions that are opposites or give rise to superior abilities that are like opposites. Does the old bloke across the way see violet mauve in his mind’s eye when he hears the train driver sound her horn, because the horn is at a pitch that his mind links with this colour, in an interaction between his perfect pitch and his coloured sound synesthesia? Does the super-recognizer in the carriage feel a tingle of familiarity from looking at two of the faces in the carriage? Is the super-taster still recovering from the second-rate coffee that he paid too much for at a fancy cafe? Is one passenger watching the screen display of info about which station the train is at like a hawk, instead of using her spare time to catch up on some reading, because she was born without any sense of time passing and can’t remotely judge the duration of her planned train journey?

Time warped: changing your perception of time. Life Matters. Radio National. July 2 2012. http://www.abc.net.au/radionational/programs/lifematters/claudia-hammond/4100994

Is synaesthesia caused by low levels of complement? Is Benson’s syndrome (PCA) caused by too much complement C3? Could synesthesia and posterior cortical atrophy be considered in some way opposites?

A note of warning – If you are thinking about copying or plagiarizing any of the text, ideas or descriptions in this post and using it as your own work without giving me (C. Wright, author of the blog “Am I a Super-recognizer?”) the proper acknowledgement and citations, then think again. If you do that you will be found out and you will regret it. If you want to make reference to this post or any of the ideas in it make sure that you state in your work exactly where you first read about these ideas. If you wish to quote any text from this post be sure to cite this post at this blog properly. There are many established citation methods. If you quote or make reference to material in this blog in your work, it would be a common courtesy to let me know about your work (I’m interested!) in a comment on any of the posts in this blog. Thank you.

Top of C3 theory post

A quote from New Scientist magazine about a study of microglia responding to changes in synaptic function in mice by Assistant Professor Beth Stevens and colleagues:

“Synapses were marked out for destruction through labelling with an immune chemical called C3”

Immune cells gobble up healthy but idle brain cells. 1 June 2012 by Andy Coghlan New Scientst. Magazine issue 2867. http://www.newscientist.com/article/mg21428675.500-immune-cells-gobble-up-healthy-but-idle-brain-cells.html

A quote about her research at Prof Stevens’ professional web page:

“C1q and downstream complement proteins target synapses and are required for synapse elimination in the developing visual system.”

Beth Stevens, PhD, Boston Children’s Hospital http://www.childrenshospital.org/cfapps/research/data_admin/Site2674/mainpageS2674P0.html

A quote from Wikipedia about synaesthesia:

“This cross-activation may arise due to a failure of the normal developmental process of pruning, which is one of the key mechanisms of synaptic plasticity, in which connections between brain regions are partially eliminated with development.”

Wikipedia contributors Neural basis of synesthesia.  Wikipedia, The Free Encyclopedia, 25 May 2012, 01:45 UTC, http://en.wikipedia.org/w/index.php?title=Neural_basis_of_synesthesia&oldid=494244732

A quote from Wikipedia about Benson’s syndrome or Posterior Cortical Atrophy:

“The disease causes atrophy of the back (posterior) part of the cerebral cortex, resulting in the progressive disruption of complex visual processing.

Wikipedia contributors Posterior cortical atrophy Wikipedia, The Free Encyclopedia, 4 February 2012, 22:34 UTC, http://en.wikipedia.org/w/index.php?title=Posterior_cortical_atrophy&oldid=475033670

Two quotes by me from this blog:

“The idea that I have something like the opposite of Benson’s syndrome would neatly draw together all the elements of some odd phenomena that I have observed over a number of years…”

“I guess the million-dollar question is  – why does Benson’s syndrome affect only some specific parts of the brain? What is it about a certain group of areas of the brain that appear to make these areas prone to hyperconnectivity in some families, and vulnerable to dysfunction in Benson’s syndrome? Is there some magic chemical or process that regulates growth in these areas of the brain? I doubt that the answer could be so simple.”

The Opposite of Benson’s Syndrome? by C. Wright Am I a Super-recognizer? January 4, 2011. https://superrecognizer.wordpress.com/2011/01/04/the-opposite-of-bensons-syndrome/

My doubt has suddenly evaporated! Could complement be the “magic chemical”? Where’s my Nobel Prize in Physiology or Medicine?

The DOI link in the New Scientist article discussed above doesn’t work, but I’m quite sure this is the journal paper that the article is about:

Dorothy P. Schafer, Emily K. Lehrman, Amanda G. Kautzman, Ryuta Koyama, Alan R. Mardinly, Ryo Yamasaki, Richard M. Ransohoff, Michael E. Greenberg, Ben A. Barres, Beth Stevens Microglia Sculpt Postnatal Neural Circuits in an Activity and Complement-Dependent Manner. Neuron. Volume 74 Issue 4 691-705, 24 May 2012. 10.1016/j.neuron.2012.03.026 http://www.cell.com/neuron/retrieve/pii/S0896627312003340

A number of other interesting journal papers can be found through Prof. Steven’s web page, some available to read in full text (if you can find the button to click on in the top right corner of the PubMed page). I also found a recently published item by Stevens and colleagues that looks like it is about the same subject as the New Scientist article, published in a conference abstract supplement of the journal Schizophrenia Research, which is a bit of a mystery as I didn’t think the title suggested schizophrenia. You need to pay to read the full text, which I didn’t. http://www.sciencedirect.com/science/article/pii/S0920996412700397

Here’s something else to read, if you’re keen. You can read the whole thing for free:

Marie-Ève Tremblay, Beth Stevens, Amanda Sierra, Hiroaki Wake, Alain Bessis and Axel Nimmerjahn The Role of Microglia in the Healthy Brain. Journal of Neuroscience. 9 November 2011, (45): 16064-16069; doi:10.1523/JNEUROSCI.4158-11.2011  http://www.jneurosci.org/content/31/45/16064.long

 

C3, C4, C5....

C3, C4, C5….

Does The Strange Phenomenon have implications for scientific understanding of object recognition and face recognition?

All around our house I have half-read copies of New Scientist magazine lying about, some months old. I had put aside an August issue because there was a story in it about visual disorders that looked like it could have been interesting. I’ve recently found the time to read it, and I’ve read it again with my brain fully switched on, and it looks as though there is an interesting relationship between The Strange Phenomenon, a face-recognition related thing that I’ve described in the first post of this blog, and two competing scientific theories about object recognition. I’m no scientist, but from what I can grasp from the science magazine article, there is one theory about visual object recognition that “we flick through a mental catalogue of objects we have seen before-and preferably, a view of these objects from every vantage point-to try to find a best fit with the current image.” I think The Strange Phenomenon indicates that face recognition works in this way, at least in my brain. The Strange Phenomenon certainly, definitely seems to work on memories of faces that are like two-dimensional photographs rather than three-dimensional models of objects. The New Scientist article reports a study by researcher Marlene Behrmann from Carnegie Mellon University in the US that is consistent with a competing theory about object recognition, that it works by memorizing objects as constructions of generic building blocks, rather than storing memories of objects as “pictures” or “scenes”.

So, does this all put together indicate that face recognition works very differently than object recognition? Does face recognition work like one theory of object recognition, while object recognition actually works like the other theory? Do our brain modules specialized for object recognition and for face recognition work very differently? Is this why prosopagnosia can be a very specific disability?  I’m just an educated housewife interpreting a report in a science magazine, so if you really want to know if this is a sensible interpretation of the research and the current theories of how our visual systems work, I strongly recommend that you go ask a person who actually works in a university.

It’s a pity the article discussed is behind a paywall on the New Scientist website.

Robson, David Seeing isn’t believing. New Scientist. August 28th 2010. Volume 207 Number 2775 p.30-33.

Online version:

Robson, David The mind’s eye: How the brain sorts out what you see. New Scientist. August 30th 2010.

http://www.newscientist.com/article/mg20727751.200-the-minds-eye-how-the-brain-sorts-out-what-you-see.html