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When Our Eyes Work & When They Don’t

Posted by Ilena Di Toro | Posted on October 4, 2022

Admit it, you don’t think much about your eyes when they are working properly. After all, that is a sign that everything is healthy. The thing is how do things work between our eyes and brain and when things don’t work, can they be fixed on the cellular and genetic level. There are two research projects that looked into those things and this is what was found.

Gaze Anchoring
Scientists at New York University’s (NYU) Center for Neural Science studied the neural mechanisms that allow us to fix our gaze on something that we are reaching for. In other words, how we are able to keep our eyes on the baseball, as we are running toward it to make a catch. They wanted to learn more about the process of gaze anchoring and how different parts of the brain communicate with each other.

The researchers studied the brain activity in the arm and eye brain regions of primates as they reached for a target.The first reach involved a coordinated look and reach. Within 10 milliseconds, another target was presented whereby the subjects needed to look at as quickly as possible. It was the second target that showed the gaze anchoring effect. These results showed that during gaze anchoring, the neurons in the part of the brain used for reaching work, known as the parietal reach region, suppresses the neuron activity in the part of the used for eye movements, known as the parietal saccade region. This suppression inhibits eye movement, which keeps our eyes focused on the target in question. This in turn enhances our accuracy.

Scientists also found that this was linked to patterns of brain waves at 15-25 Hz, known as beta waves. These waves organize neural firing across different regions of the brain. Beta waves have been linked to attention and cognition and this study showed how these waves control brain mechanisms to coordinate our behavior.

Restoring Vision After Diagnosis of Night Blindness
Congenital stationary night blindness, as the name suggested, is a form of night blindness whereby people are unable to discern objects in low light conditions. Obviously, this can make driving at night difficult. Researchers at the University of Pennsylvania School of Veterinary Medicine found out in 2015 that dogs could develop this form of blindness and in 2019 they identified the gene responsible for this condition. They reported in March 2022 in the journal Proceedings of the National Academy of Sciences, that they were able to restore night vision to dogs with type of night blindness by way of gene therapy.

Earlier research found that dogs with this condition had a mutation in the LRIT3 gene, which is the same gene that causes night blindness in people. The dogs with congenital stationary night blindness received one injection of the gene therapy that allowed the LRIT3 gene to work correctly in the dogs’ retinas. The treatment appears to be long lasting since it lasts for more than a year.

This mutation affects the ON bipolar cells’ function. These cells provide the main path from the photoreceptor to the ganglion cells. In other words, it is the shortest and most direct path for the input and output of visual signals in the retina. Interestingly enough, the overall structure of the retina of dogs with congenital stationary night blindness remained intact. This was encouraging to researchers since it gave them the idea that supplying a normal copy of the LRIT3 gene would restore night vision.

In order to do they had to identify a path for the healthy LRIT3 gene that would allow the treatment to reach the intended target. After that was done, researchers had to pair the healthy gene with a promoter, which is a genetic sequence that starts the reading of the therapeutic gene, so that it will act in cell-specific manner.

Researcher felt that by restoring the LRIT3 gene allows signals to cross from the photoreceptor cells to the ON bipolar cells. In fact, the dogs who received the gene therapy were able to navigate a maze when the treated eye was uncovered. Researchers plan to modify the therapy to use the human version of the LRIT3 gene, so that there can eventually be a human trial.

So, keeping your eyes on the target will shed light on the workings of vision. Okay, that wasn’t such a great pun, but you get the idea.


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