The research team has validated a non-invasive experimental method that can be used to study how variations in anatomical systems affect their behaviour

URV researcher Jordi Marcé-Nogué and Juan Liu from the University of Berkeley (USA) have worked together to analyse the bones of the Weberian apparatus – a part of the auditory system – of zebrafish (Danio Rerio). They have confirmed that the resonance frequency of the ear ossicles of fish coincides with their audible spectrum and that the size of these small bones does not affect how they behave. Their research has led to the development of a method to study anatomical systems in a non-invasive way, with the potential to understand and study the human body. The results have been published in the Royal Society of London’s journal Interface.

The Weberian system is part of the hearing system of zebrafish and connects their inner ear with their swim bladder, a buoyancy organ found in many fish and cetaceans. “The analogy between some human organs and the organs of these animals means that lately they have become a popular object of study,” explains Marcé-Nogué, a researcher from the Department of Mechanical Engineering. Discoveries about this species could be useful to better understand the functioning of organs in the human body or to make medical advances.

Marcé-Nogué and Liu developed a three-dimensional virtual model of the ossicles in the apparatus based on previous research and established anatomical models. This virtual model was subjected to a sweep of sound frequencies in a simulation that used the finite element method, a computational method quite common in mechanical engineering. That is, the vibration of the bones was studied when they were subjected to different sound frequencies. These sounds are transmitted through bodies and make them vibrate to a greater or lesser extent depending on the material they are made of and their structure. This analysis determined that the resonance frequency of the ossicles – that is to say, the frequency at which the bones vibrate most intensely – coincides with the audible spectrum of the animals. At the same time, they generated ten models by modifying the size of the ossicles and repeated the experimental method. The results indicate that the resonance frequency does not depend on the size of the bones, but on other factors.

The research by Marcé-Nogué and Liu has validated a methodological model that makes it possible to carry out virtual experiments on the basis of anatomical models. According to Marcé-Nogué, this allows us to use non-invasive methods to study how changes in anatomical systems affect how they behave, either because some organs cannot be accessed or because they do not even exist.

Reference: Marcé-Nogué Jordi and Liu Juan, 2024. Finite element modeling of sound transmission in the Weberian apparatus of zebrafish (Danio rerio). R. Soc. Interface. 21: 20230553. 20230553. http://doi.org/10.1098/rsif.2023.0553