# Research Project 4 - Internal state dynamics of navigation and memory

> **NIH NIH U19** · STANFORD UNIVERSITY · 2021 · $373,762

## Abstract

Research Project 4 – Internal state dynamics of navigation and memory
 Lead: Lisa Giocomo PhD
 Project Summary
In RP4 (Navigation and memory) we leverage the navigation system to experimentally investigate
theoretical and computational principles for how external sensory inputs and internal network dynamics, across
different brain states, interact to generate the neural computations necessary for navigation. We focus on four
brain regions that provide complementary computations for visually guided navigation in mice: primary visual
cortex (V1), medial entorhinal cortex (MEC), hippocampus (HPC) and retrosplenial cortex (RSC). In our first
aim, we consider how internal dynamics interact with external sensory inputs to generate a unified percept of
position. We leverage virtual reality and the high density recording capabilities of Neuropixel silicon probes to
explicitly test predictions of a Bayesian cue integration framework developed in RP3 (Theory and
computation of internal state dynamics). Here, internal dynamics reflect intrinsic path integration
calculations, while external inputs include visual landmark and optic flow inputs. In our second aim, we consider
how a change in behavioral state impacts the stability of neural maps of space and test theoretical principles,
developed in RP3 and applied to V1 in RP1 (Motivation and perception) and RP2 (Primate decision
making), for how spontaneous activity influences the detection or amplification of weak sensory inputs in the
navigation circuit. As in Aim 1, we leverage virtual reality and the high density recording capabilities of
Neuropixel silicon probes. Here, we consider a change in spontaneous activity as analogous to a change in
internal behavioral state (satiety or arousal) and consider how this impacts the stability of internal position
estimates, as measured by the spatial firing patterns of neurons, across environments with parametrically
differing external landmark strength (cue rich or cue poor conditions). In our third aim, we consider whether
driving the activity of single neurons can establish causality between neural representations in RSC and visually-
guided navigation. By applying a MultiSLM 2-photon Ca2+ imaging method developed in RP1, which enables
wide-field optical access for visualization and control of cellular ensembles in real time, we will test theories
developed in RP2 regarding attractor states and whether critically excitable regimes capable of driving behavior,
which have been observed in V1, exist in non-sensory cortical regions. Here, external input is manipulated with
single-cell resolution optogenetically, and intrinsic network dynamics for encoding internal position estimates
measured using 2P Ca2+ imaging. Together, across all of our aims, our approach of investigating multiple
navigationally relevant brain regions alongside V1 will allow us to rigorously consider the degree to which
foundational theories for classes of neural computation – developed in RP3 –...

## Key facts

- **NIH application ID:** 10047735
- **Project number:** 1U19NS118284-01
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** Lisa Giocomo
- **Activity code:** U19 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $373,762
- **Award type:** 1
- **Project period:** 2021-09-17 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10047735

## Citation

> US National Institutes of Health, RePORTER application 10047735, Research Project 4 - Internal state dynamics of navigation and memory (1U19NS118284-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10047735. Licensed CC0.

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