By Lauren Quinn
It is common to forget where you put your keys or that you have an assignment due, but what if you forget where you worked or that you have a family in the blink of an eye?
Dr. James Briggs, a professor of psychology at Susquehanna University, spoke as the annual John C. Horn lecturer on Thursday, March 27 at 4:15 p.m. in Isaacs Auditorium.
The title of his talk was: “Toward a Retrieval Model of Retrograde Amnesia: Are Memories Really Forgotten?” Briggs’ research focuses on retrograde amnesia, and how and why people forget things.
Retrograde amnesia is when someone forgets information from the past but can still form new memories.
“I might forget that I have a wife and kids,” said Briggs, as he gave an example of what may occur when someone experiences trauma that induces retrograde amnesia.
Briggs focused on two ideas as to what occurs with retrograde amnesia throughout his talk. The first was the memory consolidation theory. There are three stages to the formation and storage of memories, explained Briggs. They include encoding, storage and retrieval.
“Memories become fixated over time. According to the consolidation theory, the storage is disrupted,” Briggs explained.
Briggs explained that the consolidation theory states that new memories are vulnerable but then become more stable over time. Retrograde amnesia disrupts this process. If someone experiences a head injury that induces retrograde amnesia, they may forget what they had for breakfast that morning or dinner the night before because those memories did not have proper time to be permanently stored.
The second idea Briggs discussed was the retrieval failure hypothesis. He explained that this idea states that memories may be stored, but the retrieval process is disrupted. If a memory is in someone’s brain but the person cannot retrieve it, then it is unable to be remembered.
Briggs used mice to perform his experiments. He explained that no major harm was done to them during the procedures. To conduct his research, Briggs utilized a chamber with a black side and a white side separated by a door. The mice start in the white side.
“After a few seconds the door opens up and the animal feels exposed in that white side, they’re also curious so they scurry over to that black side, and we shut the door behind them and then we present a very brief foot shock… it’s just enough to scare them.”
Because of this, the mice associate the white side with safety and the black side with fear, explained Briggs.
Once the mice are allowed to return to the white side, they exhibit what is known as passive avoidance, Briggs elaborated.
“They remember that shock on that black side. They passively avoid that, and they say, ‘No thanks, I’m going to stay right here on this white side.’”
Briggs then explained that he observed to see how long it took for the mice to venture back over to the black side on their own, exhibiting what is called extinction.
Extinction is the weakening of a learned behavior or memory. The mice will eventually forget that the black side is associated with foot shock
Briggs also included in his talk the concept of stress and re-exposure, and how it may be possible to bring back memories and impair the extinction process.
To test this, Briggs explained how he presents a stressor to the mice during the chamber experiment, which will make them forget their fear. They then are administered cycloheximide, which Briggs stated is a substance that imitates the effects of amnesia. After a while, another stressor is presented to the mice, bringing back the fear that was knocked out from the cycloheximide.
Briggs stated, “We were able to uncover that forgotten stress memory by re-exposure.”
This is similar to the “two-bump theory,” elaborated Briggs, which is the idea that if you bump your head and forget something, then if you bump your head again, the memory will return. Despite the initial logic of this theory, there is not a lot of solid evidence to support it.
Dr. Briggs continues to actively research retrograde amnesia and memory loss, hoping to unlock even more secrets behind the how and the why.