A new study published in Nature Neuroscience suggests that nerve fibers, also known as axons, may not be the smooth lines that they are typically depicted as. Instead, researchers have found evidence that axons may actually be a series of bumps, resembling a garland of cranberries on a Christmas tree. This finding challenges the traditional view of axons and adds a new level of complexity to our understanding of the nervous system. However, it is important to note that this is still an emerging area of research and more studies are needed to confirm this unique structure.
Physicists have long known about the pearls-on-a-string shape observed in fluids when thin strands are stretched, forming beads. This phenomenon has been studied in viscous fluids like honey and aloe vera gel. Similarly, beads have been found on axons, which have malleable internal and external parts. The beaded structure of axons has not been systematically studied until recently, prompting researchers to investigate this unique feature further in mouse brains.
The researchers used a high-pressure freezing method to preserve mouse axons in their true state without altering their shape. This method allowed them to observe axons as a series of rotund blobs connected by thin tubes. While these experiments were conducted on a type of axon that lacks myelin, further experiments have shown similar structures in myelinated axons and human axons as well. The presence of nanoscopic varicosities or blobs in axons is believed to be a result of physical mechanics, as it requires less energy to form this structure compared to a cylinder.
The shape of an axon has been shown to impact the speed at which signals travel along it, according to modeling experiments and studies in mice axons. There is also evidence from the new study suggesting that the signals moving along the axons may influence the shape of the bumps as well. However, the researchers caution that more research is needed to confirm these findings, as the freezing method used in the study may have unintentionally altered the axons. Future studies will focus on understanding how pearled axons may be affected by factors such as sleep and observing axons inside living brains to further investigate their unique structure.
While the discovery of pearled axons introduces a new perspective on nerve fiber structure, it is important to approach these findings with caution. More research is needed to determine if this is a common trait among axons or a selective phenomenon. This study challenges established beliefs about axon structure, illustrating the need for continued exploration in this field. As researchers work to uncover the significance of these pearled axons, it is clear that this discovery has the potential to reshape our understanding of the nervous system. Despite the intriguing nature of this finding, it is essential to wait for further evidence before making definitive conclusions about the structure of axons.
