Ever been in a spot where you can’t put a name to a face or a face to
a name? As this ScienCentral News video reports, neuroscientists have more
information about what happens in the brain as these memories are made.
Don’t You Forget About Me
You meet someone and later you’re trying to remember his or her name.
Sound familiar? Neuroscientists call it associative memory.
“It’s a critical form of memory because it really defines us as
individuals,” says Wendy
Suzuki, assistant professor of neuroscience and psychology at the Center
for Neural Science at New York University. “Our memories for the
facts that we’ve learned and the events that we’ve experienced
in our lives is really what makes us who we are. So that’s why it’s
the focus of so much cognitive neuroscience research today.” Associative
memory is, for example, the ability to learn the relationship between unrelated
items, such as the name of someone you just met and that person’s face.
“We specifically studied the situation where you meet somebody for the
first time and you learn that person’s name,” says Suzuki. “And
you may repeat it several times and by the end of the conversation, you are
able to recall that person’s name and evoke that person’s name
if somebody reminds you about the situation.”
Suzuki and her team studied two adult rhesus monkeys playing a memory-based
video game in which an image pops up on the computer screen with four targets—white
dots—superimposed on it. The monkeys’ task was to learn which target
on which image was associated with a reward (a drop of their favorite fruit
juice).
While the monkeys played the game, called a location-scene association, the
researchers used extremely thin electrodes to monitor the electrical activity
of cells in the monkeys’ brains, specifically in the hippocampus,
the banana-shaped area of the brain that’s a hub for learning and memory.
|
One line shows the monkey's learning curve, the other shows the activity level of nerve cells in the hippocampus.
|
“We found hippocampal cells change their activity
dramatically, directly in parallel with the animal’s behavioral learning
curve,” says Suzuki, who published her research in the June 6, 2003
issue of Science.
“So, as the animal got better and better at performing this location-scene
association, some cells increase their activity dramatically, or decrease
their activity dramatically, but both in parallel with the animal’s
learning. That allows us to conclude that these hippocampal cells are very
involved in the initial formation of these new memories that the animals are
forming each day. It was kind of like being able to watch the formation, or
the birth of a new memory.”
Suzuki and her team were also interested in those cells that not only changed
their activity when learning occurred, but also sustained that change during
the entire recording session. “That suggests that these cells may be
part of a longer term circuit that underlies the long term memories themselves,”
says Suzuki.
Knowing how the normal brain works is an important key towards understanding
and treating memory-related diseases like Alzheimer’s. “To be
able to go in and intervene in devastating situations like Alzheimer’s,
where the hippocampus is full of plaques
and tangles and the person has very, very poor memory, you need to understand
how the hippocampus works normally,” says Suzuki. “What is the
normal function? What is the normal neural code that allows the hippocampus
to form new memories or to help you retain new memories? That’s what
our studies help us understand, that basic understanding of what the hippocampus
does normally. Unless you understand that, there’s no way, there’s
no hope of intervening in a sophisticated way into the functions of the hippocampus.”
Suzuki says that although they studied the activity of the hippocampal cells,
there are other strongly inter-connected brain areas that are also involved
in learning and memory. The team plans to further study how those areas may
also be “contributing to the formation of new associations.”
Funding for this research came from the National
Institutes of Health, the National
Institute on Drug Abuse, the McKnight
Foundation and the John
Merck Fund.