Month: October 2013

Raising awareness for nystagmus

Nystagmus is the word we use to describe an involuntary oscillation of the eyes. While it can be a normal physiological response to visual and vestibular sensations, there are unfortunate pathological variations which cause visual impairment. It is a relatively common condition affecting one in every two to three thousand people in the UK, and researchers are very interested in trying to determine the causes of pathological nystagmus and to understand how it might be effectively treated.

Nystagmus network is a charity dedicated to improving patient information, support and scientific research into nystagmus. I was recently at their 3rd international nystagmus research workshop to present some research findings from an investigation into physiological nystagmus. The workshop was particularly interesting because of the scope of different scientific disciplines represented. The programme started on the first day with presentations on mathematical and animal models of nystagmus. On the second day we discussed the results of retinal imaging studies, the genetics of nystagmus, and the impact of living with nystagmus on the quality of life of patients. Presentations on the final day were focused on tentative suggestions for both surgical and medical treatments.

wobblywed2013Nystagmus Network are currently raising awareness of nystagmus in the run-up to their first International Nystagmus Awareness Day on November 6th. The awareness day has been labelled “Wobbly Wednesday” as nystagmus is often referred to as “wobbly eyes”. If you have been affected by nystagmus or know anyone who has you might wish to organise an event for the day, and you can register for a supporters pack by emailing info@nystagmusnet.org. Alternatively there is a Facebook group where supporters can interact with each other.

“Remember, remember, the 6th of November”.

Hubel and Wiesel’s visual feature detectors

The announcements for the 2013 Nobel Laureates are ongoing this week, with Peter Higgs and Francois Englert sharing the Nobel Prize in Physics 2013 for their theoretical discovery of the now famous Higgs boson. As a neuroscientist interested in visual impairment it seemed appropriate to consider two important contributors to the field who shared the Nobel Prize in Physiology or Medicine in 1981 for their discoveries concerning information processing in the visual system. David Hubel and Torsten Wiesel shared the Nobel Prize in Physiology and Medicine with Roger Sperry for his separate work on the functional specialisation of the two hemispheres of the brain.

Hubel and Wiesel made some of their most important discoveries during their investigations recording the responses of individual cells in the cat primary visual cortex. Unlike many of the cells in the retina, which respond to spots of light or dark, they found that cells in the visual cortex were highly selective for edges (or lines) of a specific orientation.hypercolumn

They proposed an organisational hierarchy within which individual cells were tuned to respond to features such as the angle of visual objects. Individual cells that shared the same tuning for features were thought to be interconnected and arranged in a regular manner. They presented these concepts in the classic “hypercolumn” model wherein vertical ocular dominance columns represent input from the left or right eye and orientation columns represent neurons that are selectively tuned to edges of a specific orientation. The exact organisation of cortical columns within the visual cortex remains an interesting topic of current research.

Later, Hubel and Wiesel performed pioneering work in the area of visual development. They found that during a sensitive period early in infancy if animals were deprived of vision from one eye the ocular dominance columns for that eye would regress while the columns representing the eye that still received vision would dominate the visual cortex. This research was critical in changing clinical practice for the childhood eye disorder amblyopia (or “lazy eye”), and highlighted the importance of early corrective treatment during the critical period of visual development for children with visual impairment.

Sadly, just two weeks ago on Sunday 22nd September we heard that David Hubel had died at the age of 87. His collaborative work with Torsten Wiesel stands as having transformed our understanding of vision and childhood visual impairment.