A novel prefrontal cortex and hippocampus combined brain slice based on in vivo diffusion tensor imaging of healthy male rats

Abstract

The pathway between the prefrontal cortex (PFC) and hippocampus (HPC) has been associated with various psychiatric disorders. While hippocampal brain slices are extensively utilized, their use has traditionally been constrained in studying long connectivity between PFC and HPC due to nerve fiber rupture during the slicing process. Consequently, optimizing brain slice preparation is crucial. The experiment consisted of three phases. Initially, the structural connection of the PFC-HPC pathway was examined using diffusion tensor imaging (DTI) data from healthy male rats. Subsequently, combined PFC-HPC brain slices were created through vibratome based on imaging acquisition. Finally, the morphology and electrophysiology of the combined brain slices were analyzed. DTI findings revealed numerous nerve fibers linking the two brain regions in the rat brain. Subsequently, a successful preparation of combined PFC-HPC brain slices cut at a 7 – 8° angle relative to the middle sagittal plane was achieved using a vibratome. Hematoxylin and eosin staining results confirmed that PFC-HPC fibers remained well-preserved in the combined brain slice. Electrophysiological recordings indicated that synchronized neuronal activity occurred in the HPC upon PFC stimulation, which depended on hippocampal activity and the integrity of PFC-to-HPC connectivity. A novel procedure for the successful preparation of healthy combined HPC-PFC brain slices, maintaining a complete fiber bundle connection between PFC and HPC, is proposed. This methodology enhances the understanding of the preservation of PFC-HPC connectivity in specific angled brain slice preparations, thereby facilitating neuroscience research focused on the longrange circuitry of subregions of interest.