The efforts of scientists made to further unlock the mysteries of the ways neurons function in the human body, particularly the brain, is providing a wealth of technological applications, from artificial intelligence (AI)-based replications to chips.
For this reason, mapping out new ways of understanding the communication patterns between neurons is essential.
A team of researchers from the Laboratory for fundamental BioPhotonics (LBP) within Ecole Polytechnique Fédérale de Lausanne (EPFL) 's School of Engineering (STI) designed a study aimed at studying this phenomenon.
The Answer is in the Ions
The researchers specifically looked at the membrane potential of neurons, which refers to the resting potential of the cell's inner and outer regions created by the transfer of ions during the transmission of electrochemical signals. They observed the process in water molecules.
"Neurons are surrounded by water molecules, which change orientation in the presence of an electric charge," says Sylvie Roke, director of the LBP and co-author on the paper.
"When the membrane potential changes, the water molecules will re-orient - and we can observe that."
Their work has a two-fold importance, in the sense that:
(1) it was carried out without the "aid of (toxic) fluorescent labels or invasive electrical probes" thanks to their opting for combined illumination, patch-clamp and second harmonic imaging,
(2) its potential to offer more options to medical professionals for monitoring brain activities.
By applying this alternative technique, the researchers were able to achieve a threefold increase, resulting in "an [overall] improvement in label-free second harmonic neuroimaging sensitivity."
Improved Methods Offer More Tangible Results
Enhanced and more efficient optical imaging made all the difference in the team's work.
In fact, thanks to the contributions of the physicists Donna Strickland and Gérard Mourou, who were recipients of the 2018 Nobel Prize in Physics (along with a third scientist Arthur Ashkin for a different innovation) in October.
They received the prestigious award "for their method of generating high-intensity, ultra-short optical pulses," which means that there has already been a strong ripple effect in the scientific community in terms of applications of their techniques.
The dual laser beams used in this study involved femtosecond laser pulses. Roke elaborates on the significance of Mourou and Strickland's research to their study:
"We see both fundamental and applied implications of our research. Not only can it help us understand the mechanisms that the brain uses to send information, but it could also appeal to pharmaceutical companies interested in vitro product testing."
"And we have now shown that we can analyze a single neuron or any number of neurons at a time." No doubt the Prize-winning pair are delighted to see that their work is not only of great use to the scientific community but is promising to offer several real-world applications.
Details about the study appear in a paper, titled "Membrane water for probing neuronal membrane potentials and ionic fluxes at the single cell level", which was published December 11th in the Nature Communications journal.