Retop-MRI

Real-time, optogenetic-fMRI

Summary

In-vivo brain stimulations are often applied in basic research to study the brain architecture, investigate the impact of stimulations on the behavior, or to test possible treatments of disease symptoms. In rodent studies, optogenetic and electrical tools are commonly used to target specific brain regions. However, these stimulations may not only induce activity at the stimulation site, but also influence remote, functionally connected areas. Which areas are affected is often unknown because the propagation of activity can depend on the stimulation parameters (e.g. frequency) and in the case of disease models, the brain-wide connectivities may have undergone alterations. Non-invasive functional MRI (fMRI) can be used during these stimulations to analyses the effects in the whole brain.

The main goal of this project is to optimize und measure fMRI during various applications of rodent brain stimulations and complement in this way other findings based on histology, electroencephalography or behavior.

Research Status

We implemented multi-echo fMRI protocols to improve the sensitivity and established the methods on two preclinical MRI systems at 7 and 9.4 Tesla for mouse and rat studies. In cooperation with the groups of Prof. Haas and Prof. Diester, MRI compatible ways to implant optical fibers for optogenetic stimulations were successfully conducted. In addition, MRI compatible electrodes have been designed which are now regularly used for EEG recordings and electrical stimulations during fMRI.

In collaboration with the project team of Prof. Haas, we have investigated the functional alterations and the effect of various stimulation paradigms in the mouse model of epilepsy. In collaboration with Prof. Diester, we have started to investigate the fMRI response upon optogenetic stimulation in different prefrontal areas in rats.