Perhaps less known than neurons, glial cells represent on average 50% of the brain cells and they form the interneural matrix. Astrocytes belong to glial cells and they are a heterogeneous population with a characteristic star-shaped form. They were visualized for the first time by Camilo Golgi – who developed a cell staining technique. But only when Ramón y Cajal published his incredible illustrations, we began to glimpse their true complexity.
For a while we thought that astrocytes only had “accessory” functions, but little by little we are discovering that they are much more. For example, astrocytes supply energy – in the form of glucose – to neurons. They have extensions or “feet” that connect with the walls of the brain blood vessels, from where they obtain glucose, partially metabolize it and transfer it to neurons. In addition, these astrocytes can be connected to each other to circulate metabolites, which would allow them to “clean” the extracellular space. Thus, astrocytes assure a mechanical support, deliver nutrients, maintain the balance in the extracellular environment and fulfill protective and regenerative functions for neurons.
And there is more. There are specific subgroups of primates’ astrocytes, such as interlaminar astrocytes. The functional implication of these interlaminar astrocytes is not yet clear, but it is postulated that they would be important for long distance communication or even higher cognitive functions. In several neuropathies, such as Alzheimer’s disease and Down syndrome, a significant reduction in these cells has been observed. Other studies also suggest that astrocytes may be involved in novel object recognition, information processing, and other cognitive behaviors. Moreover, in 1985 Marian Diamond compared some regions of A. Einstein’s brain with other men’s brain and she found that the only difference was that Einstein had more astrocytes (at least 1 of the studied regions). Although we cannot conclude that these “extra” astrocytes are responsible for the genius of Einstein, it is interesting to think about the multifactorial properties of our intelligence.