“Simply put, we can use genetic tools to inject mice with drugs that artificially cause other genes and proteins to be expressed when astrocytes are activated,” says the Baylor University scientist. says Wookbong Kwon, a bioengineer and co-author of the book. the study.
These proteins of interest were primarily fluorescent proteins that cause cells to emit bright red fluorescence. In this way, the research team was able to discover astrocytes in the mouse brains that were activated during learning scenarios. Once the tagging system was in place, Williamson and his colleagues spooked the mice a bit.
“This is called fear conditioning, and it’s a very simple idea. You pick up a mouse and put it in a new box that it’s never seen before. While the mouse explores this new box, We simply deliver a series of electric shocks to the floor,” Williamson explains. Mice treated this way will remember this as an unpleasant experience and associate it with contextual cues such as the box’s appearance, smells and sounds that are present there.
The tagging system lit up all astrocytes expressing the c-Fos gene in response to fear conditioning. Williamson’s team speculated that this is where the mouse brain’s memories are stored. Once they knew that, they could move on to their next question: whether and how astrocytes and engram neurons interact during this process.
Regulation of engram neurons
“Astrocytes are really bushy,” Williamson says. They have a complex morphology with numerous micro- or nanoscale processes that permeate the surrounding area. One astrocyte can contact approximately 100,000 synapses, not all of which are involved in learning events. The researchers therefore investigated the correlation between astrocytes, which are activated during memory formation, and neurons that are tagged at the same time.
