Our nerve cells, or neurons, communicate by sending fast electrical signals called action potentials. These signals always begin in a specific part of the neuron known as the axon initial segment (AIS). The AIS is the first section of the axon — the long, thin extension of the neuron that transmits signals to other nerve cells. It acts like a control center, deciding when to start an action potential before it travels down the axon to relay information.
Scientists previously discovered that the AIS is not a fixed structure but can change in response to activity levels in the brain. This adaptability, known as plasticity, allows the brain to adjust its connections and structures to regulate electrical activity — an essential process for learning and memory. When brain activity is high, the AIS can shorten; when activity is low, it can lengthen. However, the exact mechanisms behind these changes and the speed at which they occur were unclear.
Researchers Amélie Fréal and Nora Jamann, working in Maarten Kole’s lab, have now observed this adaptability in real time for the first time. Their groundbreaking work has also identified the molecular processes that drive these changes within the axon.
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