Like a myriad of stars interacting with the expanse of space, the brain contains billions of interlaced and communicating neurons supported by the brain’s immune cells, known as glia. The most numerous of these are astrocytes known to perform a variety of tasks, such as axon guidance, synaptic support, and homeostasis. Moreover, new roles for this brain cell are discovered every year.

Astrocytes have been hypothesized as contributing to memory consolidation and memory performance, however, the roles played by astrocytes in memory are not fully understood.

Glia supports long-term memory

Now, a study from researchers at Salk Institute shows astrocytes help the brain establish long-lasting memories in mice. The team states their data suggests astrocytes play an important role in how information is transmitted and stored in the brain. The study is published in the journal Glia.

Previous studies show understanding the role of astrocytes in cognitive processes may advance the understanding of how these processes go awry in pathological conditions. Recent studies from the group showed disabling the release of gliotransmitters in astrocytes turned down a type of electrical rhythm known as a gamma oscillation, important for cognitive skills.

When the researchers tested the learning and memory skills of mice with disabled astrocytes, they identified deficits in their ability to discriminate new from familiar objects, and surroundings. The current study investigates the long-term memory of mice with disrupted astrocytes.

The current study utilizes genetically engineered animals lacking a receptor called IP3R2. Accordingly, astrocytes rely on these receptors to release calcium for communication. Hence, the mice were tested with three different types of learning and memory challenges.

Results show mice lacking IP3R2 showed the same ability to learn as normal mice. Data findings show when tested in the 24-48 hours after each initial learning process, the mice with disrupted astrocytes could still retain the information.

After two-four weeks, the trained mice were retested. It was observed that the mice missing the receptor performed much worse, making more than twice as many errors when completing the maze.

Long-term learning & memory

Data findings, after a few weeks of delay, show normal mice actually performed better than they did right after training because their brain had gone through a process of memory consolidation, however, the mice lacking the IP3R2 receptor performed much worse.

The team surmises they have shown for the first time defects in astrocytes are linked to defects in memory consolidation or remote memory. For the future, the researchers state they are planning studies to map the pathways astrocytes use to affect the long-term memory.

Source: Salk Institute

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