Inside every neuron, there's a long, thin channel, the axon, through which signals travel from the cell body to other cells. To keep this channel working, mitochondria constantly shuttle along it. These tiny organelles produce energy and move in both directions, like cars on a narrow road. But what happens if the road is too narrow and the cars are too varied?

Scientists assembled a computer model where mitochondria are not just points but objects with their own shape, flexibility, and ability to push each other. The model showed that if mitochondria are elongated and rigid, they line up and move quickly, like race cars. But short, flexible ones start interfering with each other, creating bottlenecks. The jam grows, and movement nearly stops.

The worst happens when a jam persists: mitochondria press against the axon's walls, and it starts to bulge like an overfilled hose. This could be the first step toward nerve fiber damage. So the balance between mitochondrial fission and fusion isn't just cellular housekeeping: it's a matter of neuronal survival.

This perspective helps explain why in certain nervous system disorders, such as Parkinson's disease, mitochondria become too short and jams occur in axons. The model suggests where to look for a cure: not in the mitochondria themselves, but in how they change shape and push against each other.