Matisse at Tate Modern
“An artist should never be a prisoner of himself, a prisoner of style, a prisoner of a reputation, a prisoner of success,” wrote Henri Matisse in his book Jazz (1947). It was with this book that the French painter, then already in his seventies, radically challenged his own practice.
By predicting our eye movements, our brain creates a stable world for us. Researchers used to think that those predictions had so much influence that they could cause us to make errors in estimating the position of objects. Neuroscientists at Radboud University have shown this to be incorrect. The Journal of Neuroscience published their findings – which challenge fundamental knowledge regarding coordination between brain and eyes – on 15 April.
You continually move your eyes all day long, yet your perception of the world remains stable. That is because the brain processes predictions about your eye movements while you look around. Without these predictions, the image would shoot back and forth constantly.
Errors of estimation
People sometimes make mistakes in estimating the positions of objects – missing the ball completely during a game of tennis, for example. Predictions on eye movements were long held responsible for such localization errors: if the prediction does not correspond to the eventual eye movement, a mismatch between what you expect to see and what you actually see could be the result. Jeroen Atsma, a PhD candidate at the Donders Institute of Radboud University, wanted to know how that worked. ‘If localization errors really are caused by predictions, you would also expect those errors to occur if an eye movement, which has already been predicted in your brain, fails to take place at the very last moment.’ Atsma investigated this by means of an ingenious experiment.
Localizing flashes of light
Atsma asked test subjects to look at a computer screen where a single small ball appeared at various positions at random. The subjects followed the balls with their eyes while an eye-tracker registered their eye movements. The experiment ended with one last ball on the screen, followed by a short flash of light near that ball. The person had to look at the last, stationary ball while using the computer mouse to indicate the position of the flash of light. However, in some cases, a signal was sent around the time the last ball appeared, indicating that the subject was NOT allowed to look at the ball. In other words, the eye movement was cancelled at the last moment. The person being tested still had to indicate where the flash was visible.
Even when test subjects heard at very short notice that they should not look at the ball – in other words when the brain had already predicted the eye movement – they did not make any mistakes in localizing the flash of light. ‘That demonstrates you don’t make localization errors solely on the basis of predictions’, Atsma explained. ‘So far, literature has pretty much suggested the exact opposite. That is why we repeated the experiment several times to be sure.’
The findings of the neuroscientists in Nijmegen are remarkable because they challenge much of the existing knowledge about eye-brain coordination. Atsma: ‘This has been an issue ever since we started studying how the eyes function. For the first time ever our experiment offered the opportunity to research brain predictions when the actual eye movement is aborted. Therefore I expect our publication to lead to some lively discussions among fellow researchers.’
How To: Improve your Memory
Nearly everyone wants a better memory. To just be able to remember the last item on a shopping list, or where they put their car keys. But most importantly, remember all the information for exams. This video has tips and tricks to improving your memory in all kinds of ways.
How did the zebra get its stripes? A new paper suggests one theory to explain this biological mystery: that the stripes repel insects. http://nyr.kr/1ehD1uA
“Discouraging bites from flies is obviously useful, since the insects often carry fatal diseases. Also, while a single bite from blood-eating flies extracts just a tiny droplet of blood, thousands of bites per day can add up to significant blood loss.”
Photograph: Valerie Shaff/Getty
Ian Crouch on Stephen Colbert’s transition to late night: http://nyr.kr/1ehLde8
“In a way, we’ve been more eager than Colbert himself to protect his conservative-host persona, not by believing explicitly in the fictional construct of the show, but by agreeing instead to act like we believe it.”
Photograph by Jim Lo Scalzo/EPA/Corbis.
Insights into how brain cells are produced could lead to treatments for brain cancer and other brain-related disorders.
Scientists have gained new understanding of the role played by a key molecule that controls how and when nerve and brain cells are formed - a process that allows the brain to develop and keeps it healthy.
Their findings could help explain what happens when cell production goes out of control, which is a fundamental characteristic of many diseases including cancer.
Researchers have focused on a RNA molecule, known as miR-9, which is linked to the development of brain cells, known as neurons and glial cells.
They have shown that a protein called Lin28a regulates the production of miR-9, which in turn controls the genes involved in brain cell development and function.
Scientists carried out lab studies of embryonic cells, which can develop into neurons, to determine how Lin28a controls the amount of miR-9 that is produced.
They found that in embryonic cells, Lin28a prevents production of miR-9 by triggering the degradation of its precursor molecule.
In developed brain cells, Lin28a is no longer produced, which enables miR-9 to accumulate and function.
In cancer cells, Lin28a production is re-established, and as a result this natural process is disrupted.
Researchers used a series of lab tests to unravel the complex processes that are directed by the Lin28a protein.
They say further studies could help explain fully the role of Lin28a and miR-9 in brain development, and pave the way to the development of novel therapies.
The study, published in Nature Communications, was supported by the Wellcome Trust and the Medical Research Council.
Understanding more of the complex science behind the fundamental processes of cell development will helps us learn more about what happens when this goes wrong – and what might be done to prevent it. -Dr Gracjan Michlewski (School of Biological Sciences)
Exhibitions bring out the stylish, edgy side of Collier Schorr, Malick Sidibé, Amy Arbus, Harold Edgerton, and more