New Neuronal Bridges Discovered in Mouse and Human Brains

Researchers using super-resolution microscopy have uncovered a previously unknown type of connection between neurons in both mouse and human brains.

At Johns Hopkins University, neuroscientist Minhyeok Chang and their team discovered tiny tubular structures in the tips of growing neurons in lab cultures. In subsequent studies involving mouse models of Alzheimer’s disease, it appeared these structures were facilitating the movement of calcium and other molecules related to the disease directly between cells.

The researchers noted that “similar structures can transport a vast range of materials, from small ions to large mitochondria,” as mentioned in their study.

They observed these nanotubes forming in cultured neurons and confirmed that they had a distinct internal architecture, distinguishing them from other types of neuronal extensions.

Neurons are well recognized for transmitting rapid signals via synapses—where they exchange both electrical and chemical information. However, it’s noted that different cell types use bridging tubes to trade molecules. The current study confirms that such tubular connections also exist in neurons, aided by advanced imaging techniques and machine learning.

During their experiments, the researchers saw these nanotubes transporting amyloid-beta molecules that were injected into mouse brain cells. This specific molecule is associated with neurodegenerative conditions like Alzheimer’s, where it tends to cluster abnormally.

When the scientists prevented the formation of these bridges, the spread of amyloid-beta between cells ceased, validating that the nanotubes acted as direct conduits for this substance.

The computational model aligned with these observations, suggesting that excessive activity within the nanotube network could accelerate toxic amyloid accumulation in specific neurons, linking changes in these structures to the progression of Alzheimer’s disease.

This research is still in its early stages. Given that these tubes are a novel discovery, there’s much to learn—including what substances they naturally transport and how frequently they operate within the human brain.

Moreover, the malfunctioning of these tubes might play a role in other diseases, which has spurred researchers’ interest in exploring these tiny bridges further.

This study appeared in the journal Science.