Neuroimaging in animal models
We have developed a new platform for longitudinal structural and functional MRI in rats and mice in vivo using an 11.7 Tesla Bruker Biospin animal bore. High-resolution scans are collected using Bruker’s cryoprobe pictured below, which uses cryogenically cooled gradients that minimize thermal vibration leading to superior signal-to-noise while at the same time maintaining a warm internal temperature suitable for in vivo scanning.
We have developed protocols for structural (in-plane spatial resolution of 60 μm), resting state functional (in-plane resolution of 75 μm), and diffusion weighted scans (in-plane resolution of 200 μm) in-plane, and are applying these sequences to several rodent models including mice and rats.
Reverse engineering neuroimaging signals
By conducting neuroimaging in well-characterized animal models, the neural basis of imaging signals can be validated. For example, we can quantify changes in immunofluorescence staining for the presynaptic vesicle glycoprotein, synaptophysin (SYN), in the principal hippocampal circuits to examine pre-synaptic integrity. To investigate post-synaptic integrity throughout hippocampal subfields and laminae corresponding to connectional anatomy, we quantify changes in immunostaining for the actin-associated protein synaptopodin (SYNPO), which labels dendritic spines (Deller et al. 2000) as well as the ubiquitous dendritic marker, microtubule-associated protein 2 (MAP-2). Making these critical links between brain structure and neuroimaging signals is necessary for the platform to be used effectively for longitudinal intervention studies in animals.