Researchers visualize the complex ramifications of the nervous system

Summary: The study unveils the molecular mechanism that allows neural networks to grow and branch.

Source: jale

Our nervous system is made up of billions of neurons that communicate with each other via axons and dendrites. As the human brain develops, these structures branch out in beautifully complex but poorly understood ways that allow neurons to form connections and send messages throughout the body. And now Yale researchers have uncovered the molecular mechanism behind the growth of this complex system.

Their results were published in Scientific progress.

“Neurons are highly branched cells, and that’s because each neuron is connected to thousands of other neurons,” says Joe Howard, Ph.D., Eugene Higgins professor of molecular biophysics and biochemistry and professor of physics and a senior researcher. study researcher.

“We are working on this branching process – how are branches formed and how do they grow? That’s behind the whole workings of the nervous system.”

The team studied the growth of neurons in fruit flies as they matured from embryo to larva. To make this process visible, they marked neurons with fluorescent markers and imaged them on a rotating disc microscope. Because nerve cells are located directly under the skin [outermost layer]The researchers were able to follow this process in real time on living larvae.

After imaging neurons at different developmental stages, the team was able to create time-lapse movies of growth.

In the early stages of development, sensory neurons started out with just one or three dendrites. But in less than five days, they had grown into large tree-like structures with thousands of branches.

Analysis of the dendritic tips revealed their dynamic and stochastic (randomly selected) growth, oscillating between growth, contraction and paused states.

“Prior to our study, there was a theory that neurons could expand and contract like a balloon,” says Sonal Shree, PhD, research scientist and lead author of the study. “And we found that instead of inflating like a balloon, they grow and branch out.”

“We find that we can explain neuronal growth and general morphology fairly well in terms of how cell terminals work,” says Sabyasachi Sutradhar, PhD, research scientist and study co-author.

“It means we can now focus on the tips because if we understand how they work, we can understand what the overall shape of the cell looks like,” Howard says.

From the veins and arteries of the circulatory system to the bronchioles of the lungs, there is a whole range of ramifications in biology. Howard’s lab hopes that a better understanding of branching at the cellular level will also shed light on these processes at the molecular and tissue levels.

About this research in Neuroscience News

Author: Isabella Bachman
Source: jale
Contact: Isabella Bachman—Yale
Picture: Photo credited to Howard Lab

original search: open access.
“The dynamic instability of dendrite tips creates the highly branched shapes of sensory neurons. From Sonal Shri et al. Scientific progress

summary

The dynamic instability of dendrite tips creates the highly branched forms of sensory neurons

The highly complex spines of neural dendrites provide the substrate for the brain’s increased connectivity and processing power. Altered dendritic morphology is associated with neurodegenerative diseases.

Several molecules have been shown to play critical roles in shaping and maintaining dendrite morphology. However, the basic principles by which molecular interactions produce branched shapes are poorly understood.

To illustrate these principles, we visualized the growth of dendrites during larval development fruit fly sensory neurons and found that dendrite tips are subject to dynamic instability, rapidly and randomly alternating between growth, contraction, and pauses.

By integrating these measured dynamics into a proxy-based computational model, we have shown that the complex and highly variable morphologies of these cells are a consequence of the stochastic dynamics of their dendrite tips.

These principles can be generalized to branching of other types of neurons, as well as branching at the cell and tissue level.