RGS14414 protein-mediated enhancement in encoding of both object and associative spatial memory in perirhinal cortex

M Masmudi-Martín1,2, E Martin-Montañez1, E Castilla-Ortega3, I Navarro-Lobato1,2, MD Domínguez-Pinos1, FJ Barón López1, M Cuadros Romero1, LJ Santín3, J Pavía1, ZU Khan1,2. 1University of Malaga, Dept. Medicina, Faculty of Medicine, Spain, 2University of Malaga, Lab. Neurobiology, CIMES, Spain, 3University of Malaga, Dept. Psychobiology, Faculty of Psychology, Spain

Within the medial temporal lobe (MTL), perirhinal cortex (PRh) is thought to be essential for processing of object visual memory (OVM). PRh receives the object information input through ventral stream areas, whereas spatial information input to the postrhinal cortex comes from dorsal stream areas. It is believed that information processing in ventral and dorsal streams remains largely segregated and that they do not converge within the PRh. In imaging experiments, PRh was activated significantly more by pictures of objects and pictures of novel spatial arrangements produced no effect. Thus, PRh is important in OVM and not in spatial memory. Recently, we observed that the overexpression of a regulator of G-protein signaling 14 of 414 amino acids (RGS14414) into area V2 of visual cortex led to the conversion of short-term OVM of 45 minutes into long lasting long-term OVM. However, it remains to be tested of whether this protein can produce memory enhancement effect into PRh. Therefore, we have explored the effect of overexpression of RGS14414 protein into PRh on both object and spatial memory. Lentivirus of RGS14414 gene were delivered in perirhinal cortex through steriotaxic injection. After 3 weeks of the injection in animals when RGS14 protein expressions were observed to be optimal, memory tests were started. Statistical analysis was performed using a one way ANOVA followed by Tukey-Kramer post hoc tests. Our results show that RGS14414 protein into PRh not only promoted enhancement in object memory but also boosted the spatial memory in rats. In contrast, expression of RGS14414 in area V2 showed no effect on spatial memory. Thus, in addition to the role of PRh in the formation of both object and spatial memory, these findings suggest that RGS14414 protein might activate a pathway common for both object and spatial components of visual memory.

This work was supported by the projects from Ministerio de Ciencia e Innovación (BFU2010-16500) y Junta de Andalucía (CTS-586).