The blind man can pull

News portal - Ruhr University Bochum

If mice go blind shortly after birth due to a genetic defect, it has far-reaching effects on both the organization of the cerebral cortex and memory. This is the conclusion drawn by researchers at the Ruhr University Bochum in a study that they published online on December 7, 2018 in the journal "Cerebral Cortex". In all areas of the cerebral cortex that process information from the senses, the density of receptors for messenger substances that regulate excitation and are involved in memory formation changed. The hippocampus, a structure critical to memory, was also affected.

Mirko Feldmann, Daniela Beckmann, Prof. Dr. Ulf Eysel and Prof. Dr. Denise Manahan-Vaughan from the Department of Neurophysiology was heavily involved.

Other senses sharpen after going blind

As a result of going blind, other senses become more sensitive: the sense of touch, hearing and smell become more precise. This enables blind people to orientate themselves precisely and navigate through an environment, despite the lack of visual information. However, this adaptation takes time and practice. The changes are made possible by what is known as synaptic plasticity. The term describes the brain's ability to adapt and create memories beyond childhood. Researchers can determine whether an adaptative reorganization of the brain is taking place based on the density of neurotransmitters that are important for synaptic plasticity.

Adaptation is an act of strength for the brain

The Bochum researchers used mice to study what happens in the brain after going blind. They recorded the areas of the brain in which the density of the neurotransmitters relevant for plasticity changed and compared the results with the brains of healthy mice. They also tested how well the blind mice performed in orientation tests with the help of their other senses in order to be able to draw conclusions about the animals' memory performance.

After going blind, the density of neurotransmitter receptors in the hippocampus, the most important memory structure in the brain, changed. In the months that followed, the density of neurotransmitters also changed in the visual cortex, which receives information from the visual sense, and also in the areas of the cerebral cortex that process information from the other senses.

The orientation task challenged the hippocampus of the mice. The blind animals performed worse than the healthy ones. In addition, the synaptic plasticity in the hippocampus was impaired during this time. "Immediately after going blind, the brain tries to detect the missing signals by increasing its sensitivity to visual signals," explains Denise Manahan-Vaughan, who led the study. If this does not succeed, the process of entire reorganization of the sensory areas begins, which are supported by changes in the density and function of neurotransmitter receptors in the brain. "This is stressful for the brain, and during this phase the ability of the hippocampus to store spatial experiences is apparently more difficult," continues Manahan-Vaughan.

The study was funded by the Collaborative Research Center 874 (SFB 874) of the German Research Foundation. The SFB 874 "Integration and Representation of Sensory Processes" has existed since 2010 at the Ruhr University Bochum. The researchers dealt with the question of how sensory signals generate neural maps and how complex behavior and memory formation result from this.

Mirko Feldmann, Daniela Beckmann, Ulf T. Eysel, Denise Manahan-Vaughan: Early loss of vision results in extensive reorganization of plasticity-related receptors and alterations in hippocampal function that extend through adulthood, in: Cerebral Cortex, 2018, DOI: 10.1093 / cercor / bhy297

Prof. Dr. Denise Manahan-Vaughan
Department of Neurophysiology
Medical school
Ruhr-University Bochum
Tel .: 0234 32 22042
Email: [email protected]