It is perhaps the first comprehensive review on the active communication properties of astrocytes, from the basic mechanisms to the physiological and pathological implications. The topic is, at the same time, new and relevant to the understanding of brain function and dysfunction.

“The review describes the cellular mechanisms underlying the non-electrical language of astrocyte communication and highlights its distinctive features with respect to the electrical language of neurons.”

The brain contains two categories of cells, neurons and glial. Astrocytes, specialized glial cells, are the most abundant cells in the brain, accounting for about 90% of the whole brain cell population and 50% of the brain volume. Nonetheless, their function remains quite mysterious.

For more than a century they have been generally regarded as housekeeping cells, providing structural and metabolic support to neuronal function. The latter was considered only responsible for signal communication and the integration underlying higher brain functions.

This review summarizes findings of the last 15 years that completely modify such a view, showing that astrocytes themselves are capable of communication with neighboring cells, and that this communication exerts an active and coordinated control on both neuronal activity and cerebral blood flow.

The review describes the cellular mechanisms underlying the non-electrical language of astrocyte communication and highlights its distinctive features with respect to the electrical language of neurons. It also emphasizes that a dysfunction of astrocytic communication may contribute to the development of brain pathologies.

This is a quite new concept because the previous view was that astrocytes would undergo alterations only in response to neuronal damage, whereas new evidence indicates that an altered functioning of astrocytes could be among the causes of neuronal damage. Specific examples of the astrocytic contribution to the pathogenesis of AIDS-related dementia, Alzheimer's disease, Amyotrphic Lateral Sclerosis, and other brain diseases are provided.

My group has been studying the properties of astrocytes for approximately 15 years, as we initially realized the relevance of astrocytes in glutamatergic transmission. Our most recent discoveries—summarized in the review—required a combination of sophisticated methodological approaches aimed at "decoding" the non-electrical language of astrocytes, using mostly dynamic cellular imaging techniques.

A general problem encountered in our studies was the relative lack of a basic knowledge of the biology of glial cells, particularly when compared to the corresponding knowledge about neuronal cells. This situation reflects a large bias of the neuroscience community, which has, for a long time, considered the study of glial cell function of little or no interest for the understanding of brain function. This attitude is now changing, and this change may help explain the current interest in glial cells.

I think that the introduction of a new level of understanding of the role of astrocytes and other glial cells in neuropsychiatric disorders may lead to important new discoveries and hopefully, new therapies for several human diseases of the highest social impact.