Researchers show astrocytes are crucial for establishing long-term memory in mice.
Astrocytes are the most numerous cell type present in the brain, and perform a variety of tasks, such as axon guidance, synaptic support, and homeostasis. Astrocytes have been hypothesized as contributing to memory consolidation and memory performance, however, the roles played by astrocytes im memory are not fully understood. Now, a study from researchers at Salk Institute shows that astrocytes help the brain establish long-lasting memories in mice. The team state their data suggests that 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 utilises genetically engineered animals lacking a receptor called IP3R2, which astrocytes rely on to release calcium for communication. 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 2 to 4 weeks, the trained mice were retested; results show the mice missing the receptor performed much worse, making more than twice as many errors when completing the maze. Data findings, after a few-weeks 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 surmise they have shown for the first time that 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