# Multisite analysis of hippocampal neuronal ensembles

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 2020 · $502,933

## Abstract

PROJECT SUMMARY
The hippocampus is a brain structure that is critical for normal learning and memory functions. One of the first
brain regions to deteriorate in Alzheimer's Disease is the entorhinal cortex, the key processing stage between
the neocortex and the hippocampus. This degeneration correlates with the memory deficits that are among the
first cognitive symptoms of the disease. To understand why hippocampal damage causes such severe
memory deficits, it is necessary to understand the basic computational functions of this brain region. The
entorhinal cortex is divided into two regions: the medial entorhinal cortex (MEC) and the lateral entorhinal
cortex (LEC). A long-standing theory hypothesizes that the hippocampus supports the conscious recall of
autobiographical events (“episodic memory”) by binding the different aspects of an experience—the sights,
sounds, thoughts, emotions, etc., experienced at a moment in one's life—onto a framework that represents the
spatial context in which that experienced occurred. The MEC is thought to provide the hippocampus with this
spatial framework, whereas the LEC is thought to represent the “item and events” of experience. Much is
known about how the MEC represents space, but how the LEC represents experience is much less
understood. The specific aims of this project are to test the hypothesis that the LEC encodes the location of
attended items in the external world relative to the individual (i.e., an egocentric framework), whereas the MEC
encodes both the locations of attended external items and the location of the individual in a world-centered
coordinate system (i.e., an allocentric framework). Furthermore, we will test the hypothesis that the
hippocampus incorporates new information within the spatial framework by creating new place fields when the
rat performs a discrete, attentive behavior known as head scanning, especially when that behavior is
accompanied by a reward. Finally, we will test the hypothesis that the hippocampus explicitly encodes the
identity of nonspatial, surface texture cues experienced at a given location by modulating the firing rate of the
place cell at that location (so-called rate remapping). The results of these experiments will provide crucial
knowledge about how the brain encodes and stores representations of events within their spatial contexts,
which underlies our abilities to form conscious memories of our life experiences.

## Key facts

- **NIH application ID:** 9959475
- **Project number:** 5R01NS039456-21
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** JAMES J KNIERIM
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $502,933
- **Award type:** 5
- **Project period:** 1999-12-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9959475

## Citation

> US National Institutes of Health, RePORTER application 9959475, Multisite analysis of hippocampal neuronal ensembles (5R01NS039456-21). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9959475. Licensed CC0.

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