# Viscerosensory Modulation of Brain Circuits in Larval Zebrafish

> **NIH NIH R34** · HARVARD UNIVERSITY · 2024 · $327,453

## Abstract

Project Summary/Abstract
How brain circuits are modulated by sensory signals from internal organs (viscera) during ethologically relevant
behaviors is a fundamental, yet largely unexplored question in neuroscience. Achieving a comprehensive
understanding of viscerosensory integration in the brain of unanesthetized animals has been challenging given
that neural activity measurements in the vagus nerve, the main viscerosensory input to the brain, require
invasive procedures in rodents. This project will address this challenge by using the zebrafish larva. Its
suitability for organism-wide neural activity measurement and genetic manipulation, as well as its well-
characterized behaviors, all make it an ideal system for a comprehensive systems-level investigation of
viscerosensory integration in the brain during naturalistic behaviors. In the R34 phase of the grant, this project
will focus on (1) probing visceral response dynamics like heart rate, gill ventilation, and gut motility in response
to environmental challenges; and (2) determining the viscerosensory inputs to the brain by studying the
encoding properties of vagal sensory neurons. Accomplishing Aims 1 and 2 would set the stage for
investigating the neural circuits that integrate viscerosensory information in different brain regions and their
role in behavior and decision-making.
Aim 1: Determine internal organ dynamics in response to environmental changes.
Aim 1 of the project will measure the changes in heart rate, gill ventilation, and gut motility in addition to
tracking behavioral variables like tail angle and eye position during responses to visual threat, oxygen
fluctuations, or temperature fluctuations. We will use machine learning techniques to identify discrete ‘visceral
states’ from measured internal organ dynamics. Then behavioral and visceral states will be merged using
multidimensional embedding techniques to identify discrete ‘organismal states’ and the transitions between
them.
Aim 2: Probe the encoding properties of vagal sensory neurons
Aim 2 will measure neural activity in the right and left vagal sensory ganglia of behaving fish while also
tracking the internal organ parameters described in aim 1. These datasets will be summarized using encoding
models to describe the visceral information represented in each cell of each vagal ganglion.

## Key facts

- **NIH application ID:** 10942990
- **Project number:** 1R34NS138096-01
- **Recipient organization:** HARVARD UNIVERSITY
- **Principal Investigator:** Luis Alonso Hernandez Nunez
- **Activity code:** R34 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $327,453
- **Award type:** 1
- **Project period:** 2024-08-06 → 2025-05-06

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10942990

## Citation

> US National Institutes of Health, RePORTER application 10942990, Viscerosensory Modulation of Brain Circuits in Larval Zebrafish (1R34NS138096-01). Retrieved via AI Analytics 2026-06-13 from https://api.ai-analytics.org/grant/nih/10942990. Licensed CC0.

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