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Better attention linked to bigger visual cortex

Brain focus The ability to focus your visual attention is linked to the size of your primary visual cortex, scientists have found.

The findings may help researchers better understand and ultimately treat attention problems in people who have dyslexia, autism and schizophrenia.

Vision scientist Dr Ashika Verghese from the University of Melbourne is presenting her preliminary research today at the Australasian Neuroscience Society conference in Adelaide.

"Attention is involved in any task that we do these days," says Verghese. "Understanding how attention operates has tremendous impacts."

"In the everyday world we are bombarded with so much visual information, so we need to process only that which is relevant to us," says Verghese.

Visual attention is the process that lets you select relevant information from what you are looking at.

But each of us has different visual attention abilities, and Verghese and colleagues wanted to investigate why this is so.

One theory, proposed by Professor Vidyasagar from the University Melbourne, is that while visual attention originates in the higher visual areas in the front of the brain, it requires communication between this part and the early visual areas in the back of the brain - specifically, the primary visual cortex, or V1.

To see if this was the case, the researchers investigated whether the size of the V1 is linked to the performance of visual attention tasks such as visual searching and reading.

Visual searching

The researchers carried out a visual search experiment involving 21 participants recruited from Monash University and the University of Melbourne.

"It's like a Finding Waldo game except that instead of finding Waldo, you're finding a particular shape," says Verghese.

Verghese and colleagues measured how long it took participants to find a small vertical bar hidden amongst horizontal and larger vertical bars.

They then used an MRI scan to image the size of the V1.

"There was a nice correlation between how large your V1 is with how well you performed," says Verghese.

A doubling in size of the visual cortex was associated with a four times higher attentional ability.

Verghese says the findings do not have any clinical application yet, but the size of V1 may in the future be used to better objectively quantify whether therapy for particular attention problems is working.

Reading speed

Reading also relies on good visual attention.

Previous studies have found that visual attention influences reading in children and in people with reading problems such as dyslexia.

While Verghese and colleagues found that participants that performed best at the attentional test also had faster reading times, they did not find that people with a larger visual cortex could read faster.

"V1 size only predicts attention," she says. "Just looking at V1 wouldn't predict how well you would do at reading."

This suggests the role of the size of V1 in reading speed is not so straight forward.

Verghese says this is likely because the attention required in reading involves a lot more areas of the brain than the primary visual cortex, for example the word-forming area of the brain.

Her research has been submitted for publication.