# Temporally coordinated activity in the primate hippocampus supporting memory formation

> **NIH NIH R01** · UNIVERSITY OF WASHINGTON · 2021 · $551,386

## Abstract

Project Summary/Abstract
 The hippocampus plays a critical role in the formation of new memories; however, it is not clear how
information is structured and processed by the hippocampal network in the service of memory formation. The
microcircuitry of the hippocampus is richly interconnected, which produces robust, temporally-structured
activity spanning ensembles of neurons. Microcircuit motifs resonate at characteristic frequencies when they
become active, recruiting hippocampal neurons into coordinated circuits that can be detected in the rhythmicity
of local field potentials (LFP). The hippocampal LFP in primates demonstrates a complex mixture of oscillatory
signatures, and there is often no dominant frequency in the signal during memory tasks. This stands in stark
contrast to the prominent theta band (6-10 Hz) oscillation that occurs in rodents selectively during exploration
and task performance as the animal actively processes incoming information. Theta-rhythmic activity in the
rodent hippocampus is coordinated by input from the medial septum, which is a connectional pathway that is
conserved across all mammals. Although monkeys lack this sustained archetypal theta-band activity in the
LFP, the preservation of anatomy across species suggests the presence of a circuit that would similarly govern
hippocampal information processing in primates. In this proposal, we will combine newly available
electrophysiological technology with innovative computational approaches to quantify and model complex
signals of the primate LFP. Single-unit and LFP activity will be simultaneously recorded from the full extent of
the hippocampus using chronically-implanted hyperdrives and linear electrode arrays while monkeys perform a
spatial memory task in virtual reality. In addition, we will examine the effects of medial septum stimulation on
hippocampal oscillatory dynamics and behavior. We will take advantage of novel spectral analysis techniques
to improve interpretation of LFPs characterized by transient and irregular oscillations. The proposed
experiments have the following potential outcomes: 1) to determine the relationship of hippocampal oscillatory
states to neuronal spiking and memory task events, 2) to develop data-driven computational models that
characterize patterns in hippocampal oscillations as they unfold in time and across hippocampal subfields
during memory task events, and 3) to identify the extent to which the medial septum drives oscillatory activity
mediating active processing in the hippocampus.

## Key facts

- **NIH application ID:** 10205975
- **Project number:** 5R01MH117777-04
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Elizabeth A Buffalo
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $551,386
- **Award type:** 5
- **Project period:** 2018-08-14 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10205975

## Citation

> US National Institutes of Health, RePORTER application 10205975, Temporally coordinated activity in the primate hippocampus supporting memory formation (5R01MH117777-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10205975. Licensed CC0.

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