Stability of subicular place fields across multiple light and dark transitions

Although hippocampal CA1 place cells can be strongly modulated by visual inputs, the effect of visual modulation on place cells in other areas of the hippocampal formation, such as the subiculum, has been less extensively explored. Here, we investigated the role of visual inputs on the activity of subicular place cells by manipulating ambient light levels while freely-moving rats foraged for food. Rats were implanted with tetrodes in the dorsal subiculum and units were recorded while the animal performed a pellet-chasing task during multiple light-to-dark and dark-to-light transitions. We found that subicular place fields presented a somewhat heterogeneous response to light-dark transitions, with 45% of pyramidal units showing stable locational firing across multiple light-dark-light transitions. These data suggest that visual inputs may participate in spatial information processing by the subiculum. However, as a plurality of units was stable across light-dark transitions, we suggest that the subiculum supports, probably in association with the grid cells of the entorhinal cortex, the neurocognitive processing underlying path integration. © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.The grant sponsor were the European Commission (MSVS) Higher Education Authority Programme for Research in Third-Level Institutions (SMOM). The grant number was PRESENCCIA EU FP6-027731 and SF (Synthetic Forager) FP7- ICT-217148 to M.V.S.-V.Peer Reviewe