title: Spatial and stimulus-type tuning in the LEC, MEC, POR, PrC, CA1, and CA3 during spontaneous item recognition memory.
abstract: According to the "two streams" hypothesis, the lateral entorhinal (LEC) and the perirhinal (PrC) cortices process information related to items (a "what" stream), the postrhinal (POR) and the medial entorhinal cortices (MEC) process spatial information (a "where" stream), and both types of information are integrated in the hippocampus (HIP). However, within the framework of memory function, only the HIP is reliably shown to preferentially process spatial information, and the PrC items' features. In contrast, the role of the LEC and MEC in memory is virtually unexplored, and conflicting results emerge for the POR. Moreover, the specific contribution of the hippocampal subfields CA1 and CA3 to spatial and non-spatial memory is not thoroughly understood. To investigate which of these areas is specifically tuned to spatial demands or stimulus identity (odor or object), we assessed the pattern of activation of these areas during recognition memory by detecting the immediate-early gene Arc, commonly used as a marker of neuronal activation. We report that all MTL areas were recruited during the spatial and the non-spatial tasks. However, the LEC, MEC, POR, and CA1 were activated to a comparable level in spatial and non-spatial tasks, while the PrC was tuned to stimulus-type, not spatial demands, and CA3 to spatial demands but not stimulus-type. Results are discussed within the frame of a recent model suggesting that the MTL could be segregated in terms of memory processes, such as recollection and familiarity, rather than information content.
authors: Functional Architecture of Memory Unit, Mercator Research Group, Faculty of Medicine, Ruhr University Bochum, 44801 Bochum, Germany.
authors: Zachery
authors: Z
authors: Beer
authors: Caroline
authors: C
authors: Chwiesko
authors: Takashi
authors: T
authors: Kitsukawa
authors: Magdalena M
authors: MM
authors: Sauvage
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003598:Cytoskeletal Proteins / Q000378:metabolism; D018728:Entorhinal Cortex / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009434:Neural Pathways / Q000502:physiology; D021641:Recognition, Psychology / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013028:Space Perception / Q000502:physiology*
chemical_list: D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C092069:activity regulated cytoskeletal-associated protein
keywords: Arc (Arg3.1); lateral entorhinal cortex; medial entorhinal cortex; postrhinal cortex; recognition memory