Cajal-Retzius (CR) cells were discovered at the end of the 19th century by one of the founding fathers of Neuroscience - Ramon y Cajal. Hundred years have passed and yet, we still know very little about these neurons. CR cells are crucial during prenatal development for the correct formation of the cortex. Most CR cells die soon after birth. However, there is one specific part of the brain, the hippocampus, a region important for learning and memory, where these cells survive for a long time.
The role that CR cells play in hippocampus-dependent memories is still unknown. The hippocampal-parahippocampal region forms a network responsible for spatial representation in rodents and humans. In both species, spatial navigation shows a delayed postnatal maturation, which correlates with the persistence of CR cells. CR cells are indeed located in a key position to control the development of the entorhinal-hippocampal connections. It has been previously shown that CR cells are an active part of the hippocampal circuit. The CaRe-Space project aimed to establish the role that CR cells play in the postnatal hippocampus and their contribution to the development of spatial mapping. To reach this goal, I used specific genetic and molecular tools, to ablate hippocampal CR cells at early postnatal stages. I then analyzed alterations of both the circuit of the hippocampal region and the spatial navigation system. Results collected through CaRe-Space show that the persistence of CR cells is critical for the proper maturation of the hippocampal circuit.
The last decade has seen a major global effort in trying to understand how the brain processes information. Indeed, several research groups are investigating how spatial maps are created in the brain. However, few studies have focused on how the involved circuits actually develop and what the consequences of an improper maturation are. The CaRe-Space project results are giving us a new understanding on the role that specific type of neurons play in the development of the circuits supporting learning and memory. This knowledge is fundamental to fully grasp the phenotype of neurodevelopmental disorders in which the hippocampal region is affected. Additionally, it paves the way for studies focusing on the role of CR cells in such disorders.
