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Introduction: The relationship between the entorhinal cortex (EC) and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing., Objective: We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the EC and in the granular layer of the dentate gyrus (DG) of the hippocampus., Methods: We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the DG and the adjacent EC were stained according to the Klüver-Barrera method, then the ImageJ software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the EC and layer II of the DG. Statistical analysis was subsequently performed., Results: We observed an age-related reduction in the cell population of the external pyramidal layer of the EC, and in the number of neurons in the granular layer of the DG., Conclusion: Our results indicate that ageing causes a decrease in the size and density of grid cells of the EC and place cells of the DG., (Copyright © 2021 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.)

Introduction: The relationship between the entorhinal cortex and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing., Objective: We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the entorhinal cortex and in the granular layer of the dentate gyrus of the hippocampus., Methods: We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the dentate gyrus and the adjacent entorhinal cortex were stained according to the Klüver-Barrera method, then the Image J software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the entorhinal cortex and layer II of the dentate gyrus. Statistical analysis was subsequently performed., Results: We observed an age-related reduction in the cell population of the external pyramidal layer of the entorhinal cortex, and in the number of neurons in the granular layer of the dentate gyrus., Conclusion: Our results indicate that ageing causes a decrease in the size and density of grid cells of the entorhinal cortex and place cells of the dentate gyrus., (Copyright © 2021 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.)

Kallmann syndrome (KS) is a genetic disorder which combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is characterized by the absence or reduced levels of gonadotropin-releasing hormone and anosmia due to olfactory bulb aplasia. KS treatment usually begins just before puberty, but brain sexual maturation occurs long before puberty normally at perinatal age. As brain cells implicated in the development of the olfactory and reproductive system have a rostral and a caudal origin, and the rostral origin is affected by aplasia in KS and the caudal origin does not seem to be affected, the early treatment of KS, as proposed in this paper, is to attain brain sexual maturation at the most appropriate age possible to prevent the eunuchoid behavior and appearance observed in KS., (Copyright © 2013 Elsevier Ltd. All rights reserved.)