Textbooks may have misdrawn this basic brain structure for 100 years

Scientists discovered that brain-cell axons may not be smooth tubes as textbooks have shown for more than a century, but instead naturally resemble strings of tiny pearls. Those pearl-like structures can change with neural activity and may help control how quickly electrical signals travel through the brain. Textbooks may have misdrawn this basic brain structure for 100 years.

Instead of the smooth, narrow tubes commonly drawn extending from nerve cells, some axons resemble strings of tiny pearls. These repeating bulges are not simply decorative details. Their shape appears to influence how electrical messages travel.

Researchers at Johns Hopkins Medicine brought this unexpected architecture into focus in a study published online in Nature Neuroscience on December 2, 2024. Working with mouse neurons, they found evidence that a familiar picture of brain cell anatomy may overlook an important feature of the cells’ signal-carrying extensions. Related research has since documented pearled axons in human brain tissue, extending the observations beyond mice.