The University of Utah researcher's mathematical approach has resulted in a new paper about certain proteins that appear to play a major role in creating stable memories. Such findings could illuminate more details about not only memory and learning but could eventually relate to medical problems such as Alzheimer's disease.
Bressloff had spent years on vision systems, but decided to take on a more focused topic. He eventually settled on how memories are stored in the brain. The proteins related to memory are in a constant state of change, which led Bressloff to wonder how humans can have such stable memories.
"I just started thinking about the problem and reading the literature," he said.
Bressloff spent six months working with Berton Earnshaw, a graduate student in math, to simplify certain functions of the brain to the point where they could be studied using mathematical formulas and computer modeling.
The study focuses on synapses, which are the chemical junctions between nerve cells, or neurons.
The synapse allows two neurons to communicate with one another. Each synapse involves a transmission point that sends a signal across a small gap to a receiving area.
Signals are sent in the form of a chemical substance, known as a neurotransmitter. These chemicals move across the gap and bind to receptors embedded in the receiving area.
The U. paper examines specific receptors called AMPA. An important neurotransmitter, glutamate, binds to these AMPA receptors.
These receptors are "the main workhorses in getting and receiving information from one neuron to the next," explained Earnshaw.
At any given time, some AMPA receptors are moving inside the nerve cell where they are unable to receive signals. But to maintain memory, a number of AMPA receptors are anchored in place with what are known as scaffolding proteins, Bressloff said.
The computer models examined how many AMPA receptors are anchored at the receiving area on the surface as opposed to those found elsewhere in the nerve cell. The more AMPA receptors that are anchored in place, the stronger the synapse, he said.
Earnshaw said this is a rare instance where mathematicians have contributed a paper to a neuroscience journal, a place where biology and chemistry are the more typical approaches. Memories, such as that of a human face, are likely stored across several synapses.
"So if you have damage to a few synapses, you don't lose your memory," Bressloff said.
While the paper offers some answers, many more questions remain before such a finding could be useful in a medical treatment.
There are still questions about how AMPA receptors are formed as well as how these proteins move from one part of the neuron to the other.
"It's such a complicated story," Bressloff said of understanding memory formation, "it's going to take many years to unravel."
glavine@sltrib.com
