A team of engineers from the University of Alberta has developed a technique for connecting neurons using lasers. Though the procedure has so far only been conducted in a laboratory, the researchers hope that it may one day be used to create novel therapies for neuronal injuries and diseases.

Neurons – or nerve cells – conduct electrical impulses around the central nervous system, connecting with one another at junctions called synapses. Appendages called axons carry these signals away from the main body of the neuron, known as the soma, and meet with another neuron at the synapse. These components are insulated by a fatty substance called myelin, which protects the neuron and increases the speed at which signals are conducted.

If this myelin sheath becomes damaged, or indeed if any part of the neuron is severed, this transfer of information is impeded or halted, potentially leading to a wide range of health disorders such as paralysis. Because mature neurons do not divide, they are unable to heal themselves once damaged, which is why these medical conditions are so hard to treat.

However, using a type of laser called a femtosecond laser, researchers have managed to fuse neurons together in a petri dish, achieving connection with just one to two 15-millisecond pulses. Femtosecond lasers emit optical pulses with an ultrashort duration, measured in femtoseconds – which are 10⁻¹⁵ of a second each. In previous studies they have been used to successfully fuse other types of cells together, leading the researchers to speculate that they may prove effective at connecting neurons.

Describing their procedure in Scientific Reports, the authors explain how precise tuning of these lasers allowed them to induce a process called hemifusion at the point of contact between the axon of one neuron and the soma of the next. This occurs as the femtosecond pulses destabilize and break the bonds in the fatty molecules within the membrane of each neuron, causing them to form new bonds with that of an adjacent nerve cell.

This procedure yielded a 90 percent success rate, and all new connections were sturdy enough to remain intact even when the neurons were dragged around the dish and twisted using tweezers.

Commenting on this achievement, study coauthor Abdul Elezzabi explained that while it is still not possible to “go in and treat the human spine,” this new procedure does at least “bring you closer” to accomplishing that end.