The Chemical Process of Learning in Brain Cells Revealed by Advanced Microscope

Updated | Researchers at Thomas Jefferson University have imaged the hidden biological process that takes place inside the brain during learning.

When we learn, the connections between neurons—or nerve cells—in the brain, which are related to the specific task in hand, strengthen and become larger. These connections can also be strengthened in the same way by addictions and other neurological diseases.

It is this biological process that the scientists were able to image at the cellular level using an extremely high-resolution microscopic technique, revealing structural changes that have never been seen before.

The findings, which are published in the journal Nature Neuroscience, could have important implications for our understanding of how both normal learning and "maladaptive learning" behaviors—like those seen in neurological disorders—may occur, according to Matthew Dalva, a neuroscientist from the Synaptic Biology Center at Jefferson and lead author of the study.

Using a relatively new technique called Stimulated Emission Depletion microscopy (STED), the Jefferson team zoomed right to the scale of individual cells in order to observe the connecting points between neurons—known as synapses—in real time. Synapses are where information is passed from one neuron to another via chemical messengers, enabling learning and other brain functions.

The neurons were taken from rats and mice and grown in cell cultures on a petri dish. Despite not being in the brain, these neurons still form connections with each other that grow stronger or weaker in response to different stimuli, making them a useful model for understanding what's going on in the human brain.

Not only did the team witness the strengthening of connections when they activated the neurons with learning-like signals—which has been observed by scientists before—they also found that these chemical messengers appeared to organize themselves in clumps, or "nanomodules", which dance around and multiply. This behavior was surprising, Dalva said.

These are images of nanomodules in the synapses. Matthew Dalva Lab, Jefferson (Philadelphia University + Thomas Jefferson University)

The results of the new research could have implications for our understanding of neurological disorders, according to Dalva.

"Fundamentally [the findings] help us understand how synapses are organized in a way that we hadn't before," he told Newsweek. "Many diseases are diseases of the synapse, particularly ones that we understand poorly like autism and Alzheimer's disease, so the more we can know about how synapses work, I think the better chance we have of figuring out ways to attack these diseases or treat them that we didn't know before."

This article was updated to include more information on the microscopy technique.