Diffusion Tensor Imaging of Rat Model of Obsessive-Compulsive Disorder

Introduction The localization of cognitive domains can be achieved by functional imaging modalities such as fMRI, PET and MEG. It was recently shown that voxel-wise correlation between high resolution quantitative structural MRI (e.g. diffusion tensor imaging indices, DTI) and various behavioral measures allows brain localization of cognitive performance. This approach hypothesizes that inter-subject behavioral variability is manifested by morphological tissue variability leading to functional differences. The power of this methodology was demonstrated on the memory cognitive domain, where DTI indices extracted from the hippocampus, septum, fimbria and amygdala were shown to be in correlation with learning and memory abilities. In the present study we used the same technique to localize the behavioral manifestation of the signal attenuation (SA) rat model of obsessivecompulsive disorder (OCD). This model includes several phases. In the first phases the rats learn a basic relation between light, sound, lever pressing and collection of reward. During an extinction test, excessive lever-pressing is observed without the attempt to collect the reward. This behavior reflects the same behavioral disorder that is present in clinical OCD. In this study we used a voxel-wise approach to compare regional DTI indices differences between control and SA rats.