Axon Architecture

What am I looking at?

This video features the axons and dendrites of 1,227 different neurons in the mouse brain (a small fraction of the mouse’s estimated 70-75 million neurons), appearing in sequence as the video progresses. The axons and dendrites were colored to help researchers keep track of individual projections, however, the dendrites are much smaller than the axons and colored the same hue so they can be hard to pick out in this video.

Biology in the Background

Neurons have three main structures that allow them to carry out their functions: the neuron cell body, dendrites, and axon(s). Axons are responsible for sending outgoing signals to other cells. They can form projections that travel long distances (relative to the size of the cell body) within the brain. They can stretch from one brain region to another, enabling communication between brain regions.  

Neurons communicate with other neurons in the brain, forming large networks known as neural circuits, which carry out the brain’s essential functions. Researchers can use videos like these to illustrate how different brain regions are connected at the single cell level. Understanding the organization of neural circuits and their connectivity could reveal the physical mechanisms behind complex processes like learning, memory, perception, and cognition as well as disorders that involve neuronal communication like epilepsy, anxiety and other mood disorders.

The axons you see in this video can be up to 60 centimeters (almost two feet) long.

Technique

These images were created using two-photon microscopy.