How We Learn
By Mason Conen, UM Neuroscience Major
As a senior in high school, I took an AP psychology class, mostly because my mom wanted me to. However, as the class went on, I found each topic more interesting than the last. My fascination peaked when we began looking at how the brain learns—a process known as long-term potentiation (LTP). Not only was I amazed by the idea of learning about learning, but this process sparked an interest that stuck with me. It wasn’t until I began studies at the University of Montana as a Neuroscience student that I was able to look at how LTP plays a crucial role in learning and memory. I learned how this phenomenon occurs when two neurons send synchronized signals that strengthen their connection over time.
To make a memory, information must first be introduced to the brain. This happens when we are exposed to something for the first time. We remember it for a while, but soon forget if the information is not repeated. Short-term potentiation (STP) is the name of this initial process, and it lays the foundation for LTP. On a cellular level, one neuron sends a signal to another in the form of the neurotransmitter glutamate. This signal is received by the second neuron when one type of glutamate receptor, known as the NMDA receptor, is activated. Between the sending and receiving neurons, NMDA receptors trigger a slow response and initiate a weak preliminary connection.
On the other hand, when both neurons respond repeatedly, the connection is strengthened. The sending neuron releases more glutamate which is picked up by the receiving neuron, and the receiving neuron increases the number of a second type of glutamate receptor on its surface. These receptors are called AMPA receptors, and they act more quickly than NMDA receptors. AMPA receptors convey the signal so quickly that the receiving neuron is able to provide feedback to the sending neuron. This dialogue solidifies the connection between the two neurons, which ultimately converts memories from short term to long term.
Researchers can gain insight into how vital this process is by looking at the malfunction of LTP in Alzheimer’s disease. Sic L. Chan and his colleagues at the University of Kentucky found that memory loss in Alzheimer’s patients is likely due to the destruction of AMPA receptors by a protein called caspase. As caspase destroys AMPA receptors, connections between neurons are weakened and eventually eliminated altogether. These weakened connections not only result in memory loss, but also prevent new memories from being formed.
There is still much to understand about how the brain learns under normal conditions and how to treat learning and memory deficits to restore healthy function. Perhaps in time, we will be able to help those who are afflicted with Alzheimer’s and other learning or memory deficits. As I understand more about this process, I’ll think back to my first day of AP psych class, when my mom said, “You’ll thank me one day.”