The science of first sight: Researchers reveal how a baby’s brain learns to see

Newborns start out with blurry vision but their vision focuses in a few months
The researchers raised mice in darkness to see what impact it had on their brain
The research could help with vision restoration for people with sight problems
Visual experience early in life is key in developing parts of the brain responsible for seeing moving objects

Cecile Borkhataria For Dailymail.com

Published:
15:22 EST, 9 January 2017

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Updated:
15:22 EST, 9 January 2017

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When a newborn first opens its eyes, it sees the world around it as blurry shapes.

But a few months later, its vision starts to focus and it will start to recognize people and objects.

Researchers at UNC’s School of Medicine have found out more about how the brains of baby mammal’s develop as they refine their sense of sight, and the research may also help restore sight for people with vision problems.

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The research, which was conducted on mice and published in the journal Nature Neuroscience, is part of a wider project that aims to maps the areas of the brain that play key roles in vision processing.

The proper functioning of these brain areas is also key for vision restoration in people who have vision problems.

The head researcher of the lab, Dr Spencer Smith, said: ‘Early on, there are genetic programs and chemical pathways that position cells in the brain and help wire up a ‘rough draft’ of the circuitry.

‘Later, after birth, this circuitry is actively sculpted by visual experience: simply looking around our world helps developing brains wire up the most sophisticated visual processing circuitry the world has ever known.

‘Even the best supercomputers and our latest algorithms still can’t compete with the visual processing abilities of humans and animals.

‘We want to know how neural circuitry does this.’

Using his imaging system and precision surgical methods, Dr Smith and his team could view specific areas of the brain at the level of the neuron: The cells in the brain that transmit signals

There are two subnetworks of visual circuitry, called the ventral and dorsal streams, and the latter of these is important for motion perception.

In one set of experiments, the team raised mice in complete darkness for several weeks.

Even the daily care of the mice was in darkness with the aid of night-vision goggles.

Using his imaging system and precision surgical methods, Dr Smith and his team could view specific areas of the brain at the level of the neuron: The cells in the brain that transmit signals.

They showed that the ventral visual stream in mice functioned immediately, with individual neurons firing as the mice responded to visual stimuli.

But the dorsal stream did not.

‘Keeping the mice in darkness significantly degraded the magnitude of visual responses in the dorsal stream – responses to what they were seeing,’ Dr Smith said.

The neurons in the dorsal area weren’t firing as strongly as they did in mice raised with normal visual experience.

‘Interestingly, even after a recovery period in a normal light-dark cycle, the visual deficit in the dorsal stream persisted.’

This is similar to the persistent visual problems seen in humans with cataracts in both eyes that aren’t repaired until later in life.

‘Not only did the mice need visual experience to develop their dorsal stream of visual processing, but they needed it in an early developmental time window to refine the brain circuitry,’ said Dr Smith.

‘Otherwise, their vision never properly developed.’

These experiments can help explain what happens in the ventral and dorsal streams of humans when we’re babies, when part of our vision slowly develops and we try to make sense of the world moving around us during the first few months after birth.