They are little “brain stars” that store our memories

Researchers from Baylor College of Medicinein the United States, have investigated the astrocytesstar-shaped cells that live in our brains and act as microscopic storage boxes for all our memories.

This unique filing system is accessed by a set of neurons, known as engrams, that manage the “brain stars,” regulating and retrieving memories.

Until now, it was thought that neural networks were solely responsible for learning and memory, but this is not true.

“The prevailing idea is that the formation and recall of memories involve only neuronal engrams that are activated by certain experiences and maintain and retrieve a memory,” explained Benjamin Deneen, quoted by .

“We discovered that these cells interact closely with each other, both physically and functionally, and that this is essential for proper brain function. However, the role of astrocytes in memory storage and retrieval has never been investigated,” he added.

In this research, the team used rats that were conditioned to feel fear in the face of a situation. When they were exposed to a completely different environment, they did not have the same fear response.

This fear conditioning – a learning process – triggered a subset of astrocytes that express fear. gene c-Foswhich plays a fundamental role in the circuits of this region of the brain.

“The c-Fos-expressing astrocytes are physically close to the engram neurons,” said expert Michael Williamson. “We also found that the engram neurons and the physically associated set of astrocytes are also functionally connected.”

In the background, the activation of the astrocyte pool specifically stimulates synaptic activityan astrocyte-neuron communication that flows both ways. This means that only when the mice were in a fear-associated environment were c-Foss-expressing astrocytes activated.

“But when the pool of astrocytes in the fearless environment was activated, the animals froze in the same way, which proves that activating astrocytes stimulates fear. memory recovery”, said scientist Wookbong Kwon.

Given these results, the team discovered that activated astrocytes had high levels of protein NFIA and that, when suppressed, neurons failed to retrieve memories from storage.

“When we knocked out the NFIA gene in astrocytes that were active during a learning event, the animals were unable to remember the specific memory associated with the learning event, but they managed to remember other memories”, Kwon said.

These findings, which appear in a published in Naturecould have important implications for research into conditions in which memory retrieval is compromised, such as Alzheimer’s disease or post-traumatic stress disorder.