Functional differentiation of the hippocampus along its longitudinal septotemporal axis is beyond doubt, though the factors determining this subregional specificity remain controversial. The spatial specificity gradient of hippocampal place cells decreases along its longitudinal axis from the septal pole to the temporal area. This difference in the scale of spatial representation suggests differences in the involvement of neurons in these subregions in the exploration and mapping of territories of different sizes. Using c-Fos as a marker for hippocampal neuron activation in novel environments, we studied the influences of exploration of arenas of different sizes on neuron activation in the septal and temporal subregions of fields CA1 and CA3 and the dentate fascia (DF) in C57BL/6 mice. The results of these studies showed that expression intensity was influenced by arena size, and a relationship between subregion activation factors and area size was found. Elevated c-Fos expression was seen only in the temporal part of the hippocampus, while significant changes in activation were noted in field CA3 and the DF in mice exploring the largest arena. c-Fos expression in the septal subregions showed no differences in arenas of different sizes. However, repeat testing of animals in an arena of a different size led to additional activation of expression in the temporal part of CA3 and the septal part of the DF. High neuron activity in the temporal subregion of the hippocampus may be due not only to the size of the arena explored, but also to the greater indeterminacy of a large space in terms of the biological significance of its different areas.
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Translated from Zhurnal Vysshei Nervnoi Deyatel’nosti imeni I. P. Pavlova, Vol. 70, No. 6, pp. 763–769, November–December, 2020.
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Kuptsov, P.A., Pleskacheva, M.G. & Anokhin, K.V. The Size of an Explored Space Is Reflected Differently in the Activity of Different Subregions of the Hippocampus along Its Septotemporal Axis. Neurosci Behav Physi 51, 734–738 (2021). https://doi.org/10.1007/s11055-021-01129-8
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DOI: https://doi.org/10.1007/s11055-021-01129-8