Cortical connectivity maps reveal anatomically distinct areas in the parietal cortex of the rat

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Wilber, Aaron A.
Clark, Benjamin J.
Demecha, Alexis J.
Mesina, Lilia
Vos, Jessica M.
McNaughton, Bruce L.
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Frontiers Media
A central feature of theories of spatial navigation involves the representation of spatial relationships between objects in complex environments. The parietal cortex has long been linked to the processing of spatial visual information and recent evidence from single unit recording in rodents suggests a role for this region in encoding egocentric and world-centered frames. The rat parietal cortex can be subdivided into four distinct rostral-caudal andmedial-lateral regions,which includesazonepreviously characterized as secondary visual cortex. At present, very little is known regarding the relative connectivity of these parietal subdivisions. Thus, we set out to map the connectivity of the entire anterior-posterior and medial-lateral span of this region. To do this we used anterograde and retrograde tracers in conjunction with open source neuronal segmentation and tracer detection tools to generate whole brain connectivity maps of parietal inputs and outputs. Our present results show that inputs to the parietal cortex varied significantly along the medial-lateral, but not the rostral-caudal axis. Specifically, retrosplenial connectivity is greater medially, but connectivity with visual cortex, though generally sparse, is more significantlaterally.Finally,basedonconnectiondensity,theconnectivitybetweenparietal cortex and hippocampus is indirect and likely achieved largely via dysgranular retrosplenial cortex. Thus, similar to primates, the parietal cortex of rats exhibits a difference in connectivity along the medial-lateral axis, which may represent functionally distinct areas.
Sherpa Romeo green journal; open access
Posterior parietal cortex , Retrosplenial cortex , Connectivity analysis , Automated tracing , Cortical flat maps , Connectome , Segmentation , Thalamus
Wilber, A. A., Clark, B. J., Demecha, A. J., Mesina, L., Vos, J. M., & McNaughton, B. L. (2015). Cortical connectivity maps reveal anatomically distinct areas in the parietal cortex of the rat. Frontiers in Neural Circuits, 8(146). doi: 10.3389/fncir.2014.00146