A new paper with the help of a University of Arizona author is offering new insights in how the brain learns and forgets fears.
The research looked at the most common type of cell in the brain called astrocytes, which are star-shaped glial cells that are present throughout the brain. They are not well understood, but they have widely been considered to be support cells that help connect other neurons together.
“We ultimately found that astrocytes are quite important for your memory storage and retrieval,” said UA professor and study author Lindsay Halladay.
The researchers used various methods across different teams to study how astrocytes might work with other parts of the brain as they exposed them to fear-inducing stimuli.
One team hooked up brain implants to monitor astrocytes in the amygdala of mice and exposed them to noise coinciding with low current electric shocks.
Halladay’s team used electrodes to watch neurons communicating with other parts of the brain as they manipulated astrocytes.
“To record activity and these other methods of specifically targeting circuits such as the amygdala projections to the prefrontal cortex, which is important for decision-making,” Halladay said.
Both teams manipulated the astrocytes during the experiments and as they did so, the intensity of the fear response in the mice changed in real time.
The researchers worked to extinguish the fears developed in the mice by playing just the sound without any aversive stimulus.
“Instead of having a passive role in the brain, which we used to think until we had tools to delve deeper, we now know that astrocytes are critical for fear-memory storage and expression,” Halladay said.
The strength of the role that astrocytes played in forming, remembering and moving on from fears was supported by something else.
Halladay said the findings could help with treatments in psychological conditions.
“One of the important questions in addition to how our fear memory is stored in the brain is how can we reduce fear expression when it's appropriate to do so? For example, if someone struggles with an anxiety disorder or PTSD, we want to know how can we tone down the fear if it's not appropriate to have a fearful expression,” Halladay said.
The study was published in the journal Nature.
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