A Diffusion Tensor Imaging-Based Study on the Construction of Cortical-Hippocampal Fiber Pathways in Epileptic Mice

¹ Institute of Electrical Engineering, Chinese Academy of Sciences, China
² University of Chinese Academy of Sciences, China

^a 15138584420@163.com
^b* Corresponding author: zhangchengcc@mail.iee.ac.cn

Abstract

OBJECTIVE This study investigated the structural connectivity between the prefrontal cortex (PFC) and hippocampus (HPC) in both normal and epileptic mice using diffusion tensor imaging (DTI) ,with a focus on the pattern of structural changes in the brain during the acute phase of epilepsy. METHODS Healthy male C57BL/6J mice (SPF grade) and epileptic mice induced by kainic acid (KA) injection via the tail vein were randomly assigned to the control group (NS, n = 5) and the epileptic group (KA, n = 5). The fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) values of both groups were compared and analyzed. Results from FA, MD, RD, and fiber tracking were also evaluated between the two groups. RESULTS (1) Diffusion tensor imaging findings: Compared to the NS group, the PFC-HPC pathways in the KA group showed varying degrees of FA reduction, with increases in both MD and RD. These differences were statistically significant (P < 0.05). (2) Distribution of fiber bundles across the whole brain: The total number of fiber bundles in the brains of NS and KA mice was 55,722 ± 3,798 and 50,969 ± 1,948, respectively, indicating a significant reduction in fiber count in the KA group (P < 0.05). (3) Region of interest (ROI) fiber bundle connectivity and distribution: The number of cortical-hippocampal fiber bundles in the NS and KA groups was 146 ± 39 and 70 ± 61, respectively. In the NS group, ROI connection sites were predominantly concentrated in the anterior and sublateral limbic regions of the PFC and the CA1 region of the HPC. In contrast, the KA group showed ROI connections primarily located in the prelimbic and sublimbic regions of the PFC and the dentate gyrus (DG) region of the hippocampus. CONCLUSION The present study successfully mapped the whole-brain fiber connectivity for both groups of mice. Compared to the NS group, the KA group exhibited significant reductions in fiber integration and connectivity, accompanied by myelin damage. These results suggest that the original PFC-HPC fiber pathway in the KA group was partially disrupted, with the potential generation of new fiber connections. Such alterations may contribute to the abnormal structural connectivity observed in the brain tissue of epileptic individuals.