Inah Lee

Hippocampal place cells are a model system of how the brain constructs cognitive representations and of how these representations support complex behavior, learning, and memory. There is, however, a lack of detailed knowledge about the properties of hippocampal afferents. We recorded multiple single units from the hippocampus and the medial and lateral entorhinal areas of behaving rats. Although many medial entorhinal neurons had highly specific place fields, lateral entorhinal neurons displayed

The prefrontal cortex and the dorsal hippocampus have been studied extensively for their significant roles in spatial working memory. A possible time-dependent functional relationship between the prefrontal cortex and the dorsal hippocampus in spatial working memory was tested. A combined lesion and pharmacological inactivation technique targeting both the dorsal hippocampus and the medial prefrontal cortex was used (i.e., axon-sparing lesions of the dorsal hippocampus combined with reversible i

The hippocampus is an essential neural structure in developing contextual memory in a situation in which rapid development of associative learning should occur. We tested a subregion-specific contribution in the hippocampus to memory acquisition and retrieval, using the contextual fear-conditioning paradigm. The current results suggest that all three subregions (i.e., CA3, CA1, and dentate gyrus) of the hippocampus contribute to rapid acquisition of contextual memory in the initial phase of acqu

Previous literature suggests that the hippocampus subserves processes associated with the encoding of novel information. To investigate the role of different subregions of the hippocampus, the authors made neurotoxic lesions in different subregions of the dorsal hippocampus (i.e., CA1, dentate gyrus [DG], or CA3) of rats, followed by tests using a spontaneous object exploration paradigm. All lesion groups explored normally an object newly introduced in a familiar location. However, when some of

The hippocampus is an essential neural structure for spatial memory. Computational models suggest that the CA3 subregion of the hippocampus plays an essential role in encoding and retrieval of spatial memory. The perforant path (PPCA3) and dentate gyrus (DG)-mediated mossy fibers (MFs) compose major afferent inputs into CA3. A possible functional dissociation between these afferent inputs was attempted using a simple navigation test (i.e., the modified Hebb-Williams maze). Behavioral testing was

In order to determine the role of subregions of the hippocampus in spatial working memory, this study combined selective neurotoxic lesions of the hippocampal subregions with a simple delayed nonmatching-to-place task on a radial maze in rats. Lesions of the dentate gyrus or the CA3, but not the CA1, subregion of the hippocampus induced a deficit in the acquisition of the task with short-term delays (i.e., 10 sec) and impaired performance of the task in a novel environment. All subregional lesio

Although the roles of both the hippocampus and the medial prefrontal cortex (mPFC) have been suggested in a spatial paired-associate memory task, both areas were investigated separately in prior studies. The current study investigated the relative contributions of the hippocampus and mPFC to spatial paired-associate learning within a single behavioral paradigm. In a novel behavioral task, a pair of different objects appeared repeatedly across trials, but in different arms in a radial maze, and d

Hippocampus and prefrontal cortex (PFC) process spatiotemporally discrete events while maintaining goal-directed task demands. Although some studies have reported that neural activities in the two regions are coordinated, such observations have rarely been reported in an object-place paired-associate (OPPA) task in which animals must learn an object-in-place rule. In this study, we recorded single units and local field potentials simultaneously from the CA1 subfield of the hippocampus and PFC as

Objects are often remembered with their locations, which is an important aspect of event memory. Despite the well-known involvement of the hippocampus in event memory, detailed intrahippocampal mechanisms are poorly understood. In particular, no experimental evidence has been provided in support of the role of the dentate gyrus (DG) in disambiguating such events, even though computational models suggest otherwise. In the current study, rats encountered multiple objects in different locations and