# Understanding neural circuits for associative memory in the lateral entorhinal cortex

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2021 · $393,910

## Abstract

Abstract
The entorhinal cortex (EC) and the hippocampus are the brain areas which are critically involved in the formation
and retrieval of declarative memory, and damage to this circuit results in memory impairment. In order to cure
dementias, including Alzheimer’s disease, which currently affects 5 million people in the United States, it is critical
to forward an understanding of the cellular and circuit mechanisms involved in the encoding and retrieval of
memory in this entorhinal-hippocampal circuit. The EC is anatomically segregated into two halves, the lateral
entorhinal cortex (LEC), and the medial entorhinal cortex (MEC). Although previous studies have significantly
advanced our understanding of the functional role of the MEC in spatial memory and navigation, our
understanding of the functions of the LEC remain largely unclear. Here we propose studies to investigate the
function of the LEC in the associative memory to address this critical gap in knowledge. Our approach involves
multi-faceted analytical methods including in vivo electrophysiology, associative learning tasks, optogenetic
circuit analysis methods, optical imaging and transgenic mouse lines that express Cre mice under the promoter
of cell-type-specific markers. There are three Specific Aims to the studies: (Aim 1) identify functional roles of
LEC layer II cell types in associative learning; (Aim 2) identify the role of LEC dopamine input in associative
learning; and (Aim 3) determine the causal role of LEC 20-40Hz oscillations in associative learning. If successful,
our studies will identify the circuit mechanisms for associative memory formation in the LEC and will help
establish new frameworks for understanding how the entorhinal-hippocampal circuit enables the formation of
declarative memory via the integration of multiple dimensions of sensory information.

## Key facts

- **NIH application ID:** 10198703
- **Project number:** 5R01MH121736-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Kei M Igarashi
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $393,910
- **Award type:** 5
- **Project period:** 2019-09-12 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10198703

## Citation

> US National Institutes of Health, RePORTER application 10198703, Understanding neural circuits for associative memory in the lateral entorhinal cortex (5R01MH121736-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10198703. Licensed CC0.

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