Uk-Su Choi: “Functional characteristics expected to be measured by 7T high resolution fMRI”
CiNet 1F Conference Room
Neuroscience Research Institute
Host : Yoshichika Yoshioka (PI)
Refractory suppression seen in fMRI signals is known to reflect suppression occurring during signal processing in neuronal level and we can use it for examining functional selectivity. But in case that the suppression occurs in the early stage it is difficult to know whether a refractory suppression observed in a high order area is originated from the lower order areas or the high order area. In an our previous study, by devising a paired stimulation scheme, we could measure the refractory suppression at high order areas of the fusiform face area (FFA) and occipital face area (OFA) without the inheritance of refractory suppression from the primary visual area (V1). In addition, we could estimate different signal processing time between two areas. These can make possible for us to examine functional selectivity in high order areas and signal transfer between brain areas. In another our study, we have measured a functional specificity in high order areas by ultra-high spatial resolution imaging (1mm x 1mm x 1mm). We could find, by using lateralized visual stimulation, that a significant number of ipsilateral-dominant voxels were present with contralateral-dominant voxels in a larger voxel (3mm x 3mm x 3mm) of the FFA, and that these voxels were distributed heterogeneously in the large voxel and the area, and that those ipsi- and contra-lateral voxels responded differently to a face stimulus.
This suggests that a spatial resolution of 1 mm^3 order gives more information for functional specificity. Through a study in which we used structural MRI and resting-state fMRI, we could also observe some neural plasticity reflecting musical training effects.
High spatial resolution image available with 7T scanner gives hopeful advances in fMRI studies. However, it is not so obvious what aspects of functional characteristics could be examined by 7T fMRI but not by 3T fMRI in the practical meaning. Our previous studies suggest the aspects of functional characteristics such as spatial and temporal specificities and brain plasticity to be examined more effectively by 7T fMRI.