Astrocytes, the new stars of our central nervous system?

astrocyte

What makes the human brain unique?  What feature supports intelligence and creative thinking?  Astrocytes?  Astrocytes are non-neuronal, star shaped glial cells that can be found numerously in the central nervous system.  Not only do they control synaptic strength between neurons but they also communicate amongst themselves and influence how well the brain performs.  Astrocytes release and absorb (regulate) chemicals and neurotransmitters to either amplify or suppress communication between neurons, which is the basic component of information processing and learning.

In March 2013, new studies were published in Cell Stem Cell detailing successful grafting of human astrocytes into the brains of mice.  They observed enhanced learning, memory, and synaptic transmission that surpassed normal mice.  Astrocytes undergo many changes and increase in complexity as the human brain evolves.

In 1985, neuroscientist Marian Diamond observed that Albert Einstein’s brain was no different as far as size or the number of neurons in the cortex.  However the association cortex, responsible for high-level cognition, contained many more astrocytes than the average man.  Not only did he have a generous number of astrocytes, but they were larger and had a more complex shape that penetrated many layers of the cortex.  They were able to communicate more effectively due to their expanded neural connection.  This report was groundbreaking because glia cannot generate electricity and it was previously assumed that they had nothing to do with information processing.

In 1996 S. Ben Kater and his colleagues at the University of Utah tested the potential of astrocytes by cutting a line through them with a sharp microelectrode.  This created a cell-free void between the two sides and when stimulating the calcium waves on one side the waves crossed the void to the other astrocytes with no difficulty.  These cells were sending signals through the extracellular medium rather than through physical contact.  With the advent of new technology and the research of Peter B. Guthrie, it was observed that astrocytes release ATP to stimulate the calcium ion wave.

But can genius really be linked to the individual difference in astrocytes?  There is still so much research to be done, especially in the field of psychiatric disorders.  Fewer astrocytes are seen in patients with depression while they are reactive in the brains of patients suffering from epilepsy, Parkinson’s disease, and Alzheimer’s disease.  Schizophrenia and alcohol addiction are also areas of focus.

After writing this I am left with more questions but look forward to the new developments.  What is the missing piece here?  If you have anything to add, please do!

 

More readings:

Carmignoto, G. and Haydon, P.  Astrocyte control of synaptic transmission and neurovascular coupling.  July 2006.

Astrocyte pathology and the absence of non-cell autonomy in an induced pluripotent stem cell model of TDP-43 proteinopathy.  http://www.pnas.org/content/110/12/4697.  March 2013.

 

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