Jun-Cheng Weng1, 2, Liang-Chun Lin1, Guan-Ming Chen1, Yeu-Sheng Tyan1, 2
1School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan; 2Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan
Visual system is an important and well-known example of brain function. The well-defined relationship between animal visual cortical activity and light stimulation makes this system a unique model to study neuronal function and plasticity. Response to light stimulation has been investigated by non-invasive methods, such as positron emission tomography (PET) and blood oxygen level dependent functional MRI (BOLD fMRI). However, application of the above functional mapping methods to rat cortex remains challenging because stimulation should be given during scanning. Appropriate anesthesia and stable hemodynamic conditions must be maintained throughout the whole course of experiment. In the study, we sought to establish an alternative working protocol of applying manganese-enhanced MRI (MEMRI) to map the visual cortex following light stimulation. In the results, we have mapped rat visual cortex using MEMRI and have shown a clear relationship between manganese enhanced cortical regions and light-evoked activity. It will be potentially useful to study plasticity in surgically or genetically manipulated rat brains.