ABSTRACT
A new functional MR technique, manganese-enhanced MRI (MEMRI), has been successfully proven on various vertebrate animal models. There are several advantages of MEMRI over traditional fMRI techniques such as Blood Oxygen Level Dependent (BOLD). Herberholz et al. extended the use of MEMRI to the study of invertebrate animal models. The authors succeeded in labeling activity-dependent uptake in the nervous system of crayfish and produced activation maps with 78 isotropic resolution. The experimental protocol for manganese administration in rodents has been adapted to the Aplysia. It is has been found that the optimum time for imaging was between 45 and 90 after the injection. This short time compared to vertebrate protocols is due to the open circulatory system found in this animal species. Despite its simplicity the nervous system of Aplysia can constitute a good model for studying agerelated conditions or specific diseases. Electrophysiological experiments showed that aging perturbs the neuronal circuit for tail withdrawal reflex resulting in learning failure.
