Dussaux, C., Szabo, V., Chastagnier, Y. et al. Fast confocal fluorescence imaging in freely behaving mice. Sci Rep 8, 16262 (2018). https://doi.org/10.1038/s41598-018-34472-x
'I was one of the first users of the mouse implant model A1. I was doing long-term 2-photon imaging of the mouse auditory cortex. I needed a fixation system that held the mouse in an upright position and allowed access of the microscope objective to the temporal side of the brain. None of the existing fixation methods suited my needs. So Jozsua designed a brand new implant. He took into considerations of the dimensions of the imaging setup, the position of the mouse, the location and the size of the optical window and all other details. The result was perfect. The implant was simple to install, easily to be fixed onto the setup, and the reproducibility was impressive: I could find back my field of view in minutes with days apart between imaging sessions. The movement of the mouse head was mostly unobservable. The firmness of the implant was also excellent. Some of mice were used for more than 5 months. Their implants stayed in place till the end. I highly recommend researchers with specific experimental needs to try out his system.’
Xinhe Liu, former post-doc at IBENS, ENS, Paris
'I was looking for a head fixation system that would give optical access to mouse primary and secondary visual cortex with sub-micron mechanical stability during mouse motor performance on a treadmill and without elements of the fixation system jeopardizing animal vision by occluding parts of the visual field of the animal. While I have been using different self-built fixations before, no method was truly satisfying my criteria. In this situation, additive manufacturing provided a new approach to the mechanical design problem. With YMETRY we started to develop a fixation system using a metal-printed implant as core fixation element. Profiting from the structural engineering competence of its founder, Jozsua Fodor, we followed a design process that started from 3D biometric data of the mouse head and involved structural modeling, 3D visualization, iterative optimization and prototype testing. The entire process was guided by sharing relevant information and soliciting user feedback at every stage which was a very appreciable experience of collaborative work. Since then, and after receiving approval by the institutional animal care oversight, the fixation was validated in dozens of successful experiments and proved to be tolerated extremely well by the animals. Working with YMETRY gave me access to a professional skill and tool base for mechanical micro-engineering usually not available in biomedical research institutions. Based on my own experience, I highly recommend the services offered by YMETRY for design and manufacture of fully customized biometric implants and animal experimentation systems.'
Walther Akemann, post-doc CNRS, Paris, January 2020
'In order to record activity in both the primary S1 and secondary S2 somatosensory cortices by means of electrophysiology and 2-photon calcium imaging in head-fixed mice performing a sensorimotor task, I needed head fixation implants which are: 1) strong and light; 2) quick to slide into the head fixation holder; 3) providing easy access to S1 and S2 regardless of the recording method 4) and limiting motion artifacts related to the motor activity of the animal. To fulfil these requirements, Jozsua designed titanium implants of less than 2 g, which fit closely the curves of the skull, making the implantation process simple and reproducible from one mouse to another. The implants were also engineered to maximize the skull adhesion, by using a large contact surface that recover sa widepart of the parietal and occipital bone. Their porous texture creates an excellent surface for attachment to dental cement. This makes Jozsua’s implants highly resistant to the forces exerted by head-fixed mice wiggling in their holder, and limits implant detachment accidents during training. The major innovation of the implants designed by Jozsua specifically for this project consists in the inclusion of a thin titanium ring around S1-S2, making the skull around this region firmly anchored to the implant, and by extension, to the entire head fixation system. The head of the animal when attached in such a manner by Jozsua‘s head-post is then highly stable, thereby minimizing mechanical artifacts and increasing the quality of neural recordings. Lastly, the dovetail-shaped head of the implant designed by Jozsua is optimal to ensure a very quick and simple insertion into the holder, thus contributing to reduce the stress of mice during the fixation process.'
Sophie Hubatz, PhD student at NeuroPSI, CNRS, Gif-sur-Yvette.