Those who see without looking: the curious phenomenon of hemineglect.

A rare disorder caused by a brain lesion that makes us ignore half of reality.

A camera, when recording, captures images. But behind that camera there is always a production team that pays attention and gives importance to the information that has been captured. It elaborates the information, manipulates it, selects it, understands it. It processes it and then shows the result of that processing to an audience that will store that information and use it later.

Our brain works in the same way. We capture stimuli, we receive information from the outside constantly through our eyes and, just as an equipment would do, it is processed by our brain, and stored, to use it in other moments of our day to day.

But what would happen if the lens of that camera captured images for a while, but then all the information it captured was not paid attention to and just sat there, useless, useless? This is what happens to people who have an attention disorder called hemineglect, or spatial neglect. or spatial neglect.

What is hemineglect?

The hemineglect is a disorder that appears as a consequence of an acquired brain damage (for example, a brain tumor, an ischemia or a hemorrhage) in the right posterior parietal lobe, mainly. Precisely because it is in the right hemisphere and because the pathways that go up to the brain are contralateral (they cross each other, going from one side to the other), everything that is captured by the left eye is what is not processed.

The key to this disorder is that the left part of what is in the attentional focus is not processed, no attention is paid to it.is not paid attention to.

People suffering from this disorder experience some situations in their daily life such as the following: they make up only the left side of their face (since the right side of the face reflected in the mirror is captured by the left eye), at mealtime they only eat the right side of the plate and everything must be placed on this side. When they try to read, they fragment sentences and words, so what they read does not make any sense and they have to make it up. They also have problems writing, since they do not handle spaces well. In addition, this disorder also affects the limbs on the left side, since they do not see them and forget to use them.

How is it different from blindness?

The difference between blindness and hemineglect is that a person with blindness can learn to locate objects in 360-degree space. a person with blindness can learn to locate objects in a 360-degree space, with difficulty, of course, but with success.with difficulty, of course, but they can do it. This is due, in part, to the fact that the person knows that there is "something" in that space and is aware that, although he/she does not see the objects that are there, in the end he/she manages to achieve a small degree of normality in his/her life despite the limitations. On the other hand, for a person with hemineglect his space has only 180 degrees, because the other 180 for him are not there. People with this disorder have anosognosia (lack of awareness of illness).

As a result of this one can think that, sometimes, it is more important that "realization equipment" that we have in our brain than the lens that captures images, because in the future we may be able to change that lens for another one if it is damaged. But... Will we ever be able to change an impaired cognitive function into a functional one?

Currently, there are several techniques to rehabilitate people suffering from this pathology. The aim of such rehabilitation is not to cure hemineglect, as this is a chronic disorder. However, work is being done to teach people who suffer from the disorder to live with it and to have a better quality of life. Some of the most effective techniques are the use of prisms (placing them next to the right eye so that the person could see what is to the left looking in the mirror) and cognitive reeducation (teaching the patient to turn his head to the left enough to perceive his entire visual field with the right eye).

Author: Maria Vega Sanz