Brain / Research at the Hebrew University: the part responsible for analyzing visual messages is used by the blind from birth for other operations - such as verbal memory
Yuval Dror
Direct link to this page: https://www.hayadan.org.il/visionbrain.html
The visual cortex is the part of the brain responsible for analyzing visual messages. In the case of the blind from birth, naturally, it is not used for this purpose. Until recent years, scientists believed that the lack of use of the visual cortex in people blind from birth causes its degeneration. A new study conducted at the Hebrew University reveals that it is possible that the visual cortex, which is located in the back of the brain, changes in the first years of blind people's lives, so that it can perform other actions such as using verbal memory - which are not
are carried out in this part of the brain in sighted people.
As part of the study, two groups - one of sighted people and the other of blind people - were asked to memorize dozens of words and then repeat them. This, in order to check the activity taking place in their minds. About six months later, both groups were called to the researchers. "We read them a group of words and they were asked to say which of the words had been mentioned half a year before," said one of the study's editors, Dr. Ehud Zahari. "The blind could say with 90% accuracy what the words were that they were asked to memorize. The sighted group remembered the words in much lower percentages."
The research, conducted by Dr. Zahari and doctoral students Amir Amadi and Naa Raz from the Department of Neurobiology at the Institute of Life Sciences and the Center for Neural Computation at the Hebrew University, in collaboration with Prof. Rafi Malach from the Weizmann Institute, is published in the American magazine "Nature Neuroscience
In recent years there have been studies that have shown that the brains of people blind from birth use the visual cortex to analyze messages that come through touch. It turned out that when blind people read Braille, activity occurs in this cortex. In the new study, 10 blind from birth were examined using functional imaging technologies (fMRI) at the Ichilov Hospital. It turned out that the visual cortex in their brains came into action not only when touching objects, but also when they were asked to perform actions that require the use of verbal memory, such as retrieving the names of objects.
"The visual cortex, which is used to process visual messages in sighted people, became active in the blind when they were asked to read words they had previously memorized, or performed other actions related to verbal memory," said Zohari. "In sighted people, there is no such activity in these areas when performing memory tasks. Our conclusion is that, contrary to what was accepted until recently, the visual cortex is probably used to perform high cognitive functions." According to him, the blind from birth are better at verbal memory tasks than the sighted population.
According to Zohari, it is not yet known how the change taking place in the brain takes place. "One of the possibilities is that the change is based on existing connections between the visual cortex and the areas responsible for memory in the frontal cortex and the lateral lobe," he explained. "There is evidence that these connections are stronger in babies but gradually weaken. It is possible that these connections in the blind from birth are preserved or even strengthened in the absence of visual messages, thus enabling the active participation of the visual cortex in higher functions."
A few months ago, Dr. Zahari was at the center of a petition submitted to the High Court against him and the university, in which organizations opposed to animal experiments demanded that he stop his experiments on monkeys. The claim was rejected. Zohari emphasized that monkeys were not used in the current study. "The imaging method makes it possible to learn about processes that occur in the brain at the macro level. However, in order to understand how the memory mechanisms work, the neural mechanisms must be studied at the cellular level in animals," he said.
