Abrain is nothing if not communicative. Neurons are the chatterboxes of this conversational organ, and they speak with one another. By exchanging pulses of electricity using chemical messengers called neurotransmitters. By repeating this process billions of times per second. A brain converts clusters of chemicals into coordinated actions, memories and thoughts. Researchers study how the brain works by eavesdropping on that chemical conversation. But neurons talk so loudly and often that if there are other, quieter voices, it might be hard to hear them. For most of the 20th century, neuroscientists largely agreed that neurons are the only brain cells that propagate electrical signals.
A Communicative Web
The catch-all name “glia” — from the Phone Number List Greek word for “glue” — for all brain cells that aren’t neurons, like astrocytes. Conveys scientists’ initial view that their main purpose was to hold neurons together. However, since the first description of astrocytes in 1865. Researchers have discovered that they can do much more. For one thing, they have glutamate receptors. Which they use to detect and clean up excess neurotransmitters in the spaces around neurons. What’s been less clear is whether they can use glutamate to generate an electrical signal on their own. In 1994, researchers stimulated astrocytes in a dish and saw nearby neurons appear to respond by preparing to send a signal.
A New Class of Brain Cell
Volterra took advantage of a new approach Chine Directory to studying the brain. Single-cell RNA sequencing. Which takes a snapshot of the complete suite of genes active in individual cells throughout a tissue. Combing through eight databases of mouse hippocampal cells, he identified nine clusters of astrocytes. Distinguished by their gene activity. Astrocytes in one — and only one — of the clusters transcribed proteins known. To be involved in neurotransmitter storage, release and transport using vesicles, as occurs in neurons. The cells were not evenly distributed across the brain region, or even throughout specific circuits. To see whether people have these cells, Volterra and his team searched three databases of human hippocampal cells for the same protein signatures they had seen in the mouse astrocytes.
