Astrocytes are a particular type of star-shaped cells that support neurons in the central nervous system ensuring the isolation of the nervous tissues and their protection from external objects in case of lesions.
They envelop synapses (structures that permit communication among cells in the central nervous system) like duct tape, but many of their features have not yet been explored.
Scientists have long debated on their possible role in the transmission of electrical impulses, and now a study published in “Neuron”, a highly regarded scientific journal, reconsiders their importance as regulators in the transmission of information.
It seems indeed that astrocytes are a fundamental element in the construction of long term memory, of the type of memory, in particular, that is responsible for the visual recognition of objects in the context of a very specific cortical area (the perirhinal cortex) and is compromised, sometimes seriously, in patients with neurodegenerative disease.
The study conducted by Marco Canossa, physiologist at the Centre for Integrative Biology (Cibio) of the University of Trento, underlines the importance of astrocytes as a catalyst for the transmission of signals from neuron to neuron.
«These cells do not only support neurons providing a sort of scaffolding that ensures communication among them, they also appropriately regulate and supply a protein, BDNF (brain-derived neurotrophic factor), that acts like an “endogenous drug”, amplifying the work of neural synapses and enabling us to learn and remember new information. They fulfil their function with great efficacy and accuracy because a single astrocyte can activate and regulate the information flow among over 100,000 neurons».
This discovery opens new perspectives in the treatment of conditions that involve memory loss in the visual recognition of objects. «The artificial administration of BDNF directly to neurons is technically difficult, and keeping the process under control is complicated. It is much better to exploit the effectiveness of astrocytes and let them work like a complex irrigation system that provides a controlled administration of BDNF. This facilitates the work of synapses and trains the brain to perform better».
BDNF belongs to the family of neurotrophins, whose discovery earned Rita Levi Montalcini the Nobel Prize in Medicine in 1986. Today, the attention of scientists from all over the world is directed to this family of growth factors, and even the University of Trento opened a research line on this scientific subject with the arrival of Macro Canossa.
The paper, whose leading author is researcher Beatrice Vignoli of Cibio, is the product of a concerted effort between the University of Trento and the European Brain Research Institute (EBRI) Rita Levi-Montalcini in Rome, with which Marco Canossa started a long and fruitful collaboration.
Canossa’s study reopens a decade-long debate on the role of astrocytes and places even more emphasis on possible developments, making it clear that these cells do play a role in processes that influence long term memory involved in object recognition. «We did know that astrocytes were not to be underestimated. After all, we have known for years that the human brain is different from the brain of other species because, among other things, has larger astrocytes that can connect a considerable number of neurons, and is therefore more efficient in managing memory information and stronger in terms of learning and memory abilities. The challenge for researchers now - added Canossa - is to find out if and how this discovery can have an impact on other memory areas of the cerebral cortex».
Read the article here: http://www.cell.com/neuron/fulltext/S0896-6273(16)30632-8