Human Brain Cells Make Mice Smarter
The results of a study conducted by scientists at the University of Rochester indicate that the evolution of astrocytes – the most famous microglial cells of the brain – may be one of the key mechanisms that endowed a person with intelligence that distinguishes him from other representatives of the animal world.
As is known, in addition to neurons, brain tissue is formed by glial cells, the most famous representatives of which are astrocytes. The role of glial cells is to ensure the vital activity of nerve cells, including the formation of conditions optimal for the transmission of nerve signals.
Compared to the brain tissue of other animals, human brain tissue contains a larger number of astrocytes, which are characterized by larger sizes and greater diversity. Human astrocytes can form many fibrous processes that simultaneously connect with a large number of neurons, especially with synapses – places of contact between the processes of neurons through which nerve impulses are transmitted from cell to cell. As a result, individual human astrocytes have the ability to coordinate the activity of thousands of synapses, which far exceeds the capabilities of mouse astrocytes.
This observation formed the basis of the assumption that astrocytes may play an important role in providing the most complex signaling activity of the human brain and, accordingly, the mind.
To test this hypothesis, the authors isolated glial progenitor cells from human brain tissue and implanted them into the brains of newborn mice. As the animals matured, human cells practically displaced their own glial cells, which did not entail changes in the neural network of the mouse brain.
The study of the consequences of such transplantation revealed two important indicators indicating a significant increase in the functionality of the animal brain. One of them was a significant increase in the speed of the so–called calcium wave - the process of signal propagation through contacting astrocytes. The second indicator was faster and more stable long–term potentiation, a process considered one of the main molecular mechanisms underlying memory and learning, and estimated as the duration of the period of neuronal response to short-term electrical stimulation.
To obtain practical confirmation of improving the functionality of the brain, animals were subjected to a series of behavioral tests designed to assess memory and learning ability. The results showed that mice with human microglia learned much faster, as well as formed new associations and performed various tasks much faster than ordinary animals.
The authors believe that the animal model created by them is a valuable tool that provides specialists with new opportunities to study and develop methods for the treatment of neurological diseases, the development of which involves microglial abnormalities.
Article by Han et al. Forebrain engagement by human glial progenitor cells enhances synaptic plasticity and learning in adult mice is published in the journal Cell Stem Cell.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Futurity: Human brain cells make mice smarter.
12.03.2013