Through a new study on rodents, scientists have made first-of-a-kind observations of the brain mistakenly recalling a memory. The researchers were able to identify patterns of brain cell activation as mistakes were made during memory experiments, which the scientists believe lays the groundwork for understanding the mechanisms at play in memory disorders such as Alzheimer's disease.
The work was carried out at the University of Texas at Austin, where neuroscientists carried out experiments on rats that were tasked with remembering the location of food throughout a series of mazes. The researchers used electrophysiological recordings to gather and analyze brain signals as the rats completed the memory tasks, with a focus on the hippocampus, the brain region where memories are stored.
In experiments where the rats were able to correctly remember where the food was and locate it, the scientists were able to identify a specific pattern of brain cells activating, with similar timing.
“We could see the memories activating,” says Laura Colgin, an associate professor of neuroscience at the University of Texas at Austin and lead author of the paper. “It’s like dominoes falling. One cell activates and then the next fires.”
In experiments where the rats incorrectly recalled the location of the food, the scientists observed the same patterns but the timing of cell activation differed. This came as a surprise to the scientists, who instead expected to see the cells activate in a jumbled sequence.
“The activation started later and it was slower, but the same pattern fired,” Colgin says. “There may be less energy in the network to drive the cells, and that may be why memory was not connected with action.”
Interestingly, the scientists found the rats that were able to correctly recall the location of the food were tapping into that memory between tests, with the same pattern of cells activating even when resting. The scientists liken this to the way someone might practice a speech before delivering it, and found that when the rats made mistakes, they weren't accessing the memory and activating the cells during their periods of rest.
Because the hippocampus is a region of the brain that deteriorates in Alzheimer's patients and is where humans also store most of their memories, the scientists believe the findings can inform these fields of research moving forward. This could include not just coming up with treatments for memory disorders like Alzheimer's, but helping our broader understanding of how memories are formed and even how they might be retrieved.
“If we can understand how these large ensembles of neurons that represent memories are formed and what’s happening when these memories are being properly retrieved, someday we may be able to decipher and store memories,” Colgin says.
The research was published in the journal Nature Communications.
Source: University of Texas at Austin