A new study from the META-BRAIN project has developed a computational framework to predict the electric fields generated by magnetoelectric nanoparticles (MENPs) in brain tissue, providing a new tool to guide the design of future neuromodulation experiments.
Published in Advanced Science, the research connects processes occurring at very different scales, from the behaviour of a single nanoparticle to the combined electric fields produced by multiple MENPs distributed within cortical tissue. This multi-scale approach makes it possible to investigate how factors such as nanoparticle size and concentration influence their potential for neuromodulation.
The study, “A Multi-Scale Computational Framework for Evaluating Wireless Neuromodulation Feasibility via Magnetoelectric Nanoparticles”, brings together researchers from META-BRAIN partners CNR-IEIIT, ETH Zurich and IDIBAPS. The authors are Marta Bonato, Elric Zhang, Emma Chiaramello, Serena Fiocchi, Giulia Suarato, Valentin Gantenbein, Nathalia Cancino Fuentes, Alejandro Suarez-Perez, Maria V. Sanchez-Vives, Salvador Pané and Marta Parazzini.
A digital twin for neuromodulation experiments
Testing different combinations of nanoparticle characteristics and stimulation conditions experimentally requires extensive laboratory work. Computational modelling offers a complementary way to reproduce experimental conditions virtually and investigate the physical processes involved.
The new framework connects three levels of analysis:
- First, at the individual nanoparticle level, the researchers modelled core-shell MENPs using experimental measurements of their physical and magnetic properties. The simulations showed that increasing the diameter of the magnetostrictive core from 15 to 20 nanometres increased the electric potential generated at the nanoparticle surface by approximately 49% under the conditions analysed.
- Second, at the experimental setup level, the model reproduced an in vitro configuration consisting of cortical tissue exposed to a magnetic field generated by a coil. Even with a magnetic field of 100 mT, the electric field induced by the coil remained below 1 V/m, allowing researchers to distinguish this baseline effect from the additional electric fields generated when MENPs are present.
- Third, at the tissue level, the framework modelled multiple MENPs distributed within cortical grey matter, combining their contribution with the electric field generated by the coil.
Concentration influences the predicted electric field distribution
At the tissue level, the researchers compared MENP concentrations of 0.1% and 0.2% w/v, using multiple random spatial distributions to account for variations in how the nanoparticles may be dispersed through the tissue.
The simulations predicted widespread electric fields above 10 V/m at both concentrations, covering approximately 77% of the simulated tissue at 0.1% and 92% at 0.2%. Increasing the concentration also expanded the areas exposed to stronger fields. The proportion of tissue above 100 V/m, for example, increased from approximately 11% to 20%.
“Our results show that nanoparticle concentration can substantially change both the extent and intensity of the predicted electric fields in the tissue. This gives us an important parameter to consider when designing and testing different stimulation conditions experimentally”, explains Marta Bonato, first author of the study and researcher at CNR-IEIIT.
The study does not establish these predicted electric fields as a direct measurement of neuronal response. The authors emphasise that electrophysiological validation remains necessary and identify several aspects to be incorporated into future models, including nanoparticle aggregation, interactions with cell membranes and realistic neuronal morphologies.
Connecting modelling with META-BRAIN experiments
“Computational modelling allows us to explore different conditions before moving to experimental validation and, importantly, to interpret experimental observations from a physical perspective. Bringing modelling and experiments together is essential for understanding and progressively optimising magnetoelectric neuromodulation within META-BRAIN”, says Marta Parazzini, senior author of the study and researcher at CNR-IEIIT.
This work complements experimental research recently published by META-BRAIN researchers in Advanced Science, which showed that MENPs can enable low-intensity magnetic fields to modulate cortical network activity in vitro. While that study provided experimental evidence of changes in neuronal activity, the new computational research helps quantify the electric fields that MENPs may generate and explore the physical conditions underlying this approach to neuromodulation.
The publication is available in Advanced Science: https://doi.org/10.1002/advs.77667
Other scientific papers related to META-BRAIN can be found in our Publications section: https://meta-brain.eu/publications/
