# Circadian output mechanisms in nocturnal and diurnal animals

> **NIH NIH R35** · TEXAS A&M UNIVERSITY · 2024 · $158,907

## Abstract

Project Summary
Animals have evolved circadian (near-24 h) rhythms to anticipate and adjust their behavior to daily
opportunities and challenges such as mating, food availability, and predation. These behavioral rhythms are
synchronized to the solar day by the central circadian pacemaker, the suprachiasmatic nucleus (SCN). SCN
neurons exhibit daily rhythms in firing rate and clock gene expression that communicate circadian time to the
rest of the brain and body. However, critically, we do not know how SCN signals interact with molecular and
neuronal clocks in downstream neurons to generate circadian outputs. Our lab’s overarching goal is thus to
understand how circadian input from the SCN is encoded by target neurons to ultimately generate diverse
behavioral rhythms that peak at different times of day. To address this, over the next five years, our research
program will focus on several interrelated but independent themes, including defining the “transfer function” for
circadian output circuits, determining how molecular clocks in target neurons contribute to behavioral
rhythmicity, and understanding how target neurons integrate diverse inputs to generate behavioral rhythms.
We propose that endogenous rhythmicity in downstream neurons and daily input from SCN neurons are each
required to drive appropriately timed circadian behavioral outputs. Here, we will use multi-level analysis at the
molecular, circuit, and behavioral levels including targeted genomic editing of clock genes, in vivo and ex vivo
imaging of rhythmic neurons, and machine learning analysis of behavior to dissect circadian output circuitry in
two complementary species, the nocturnal laboratory mouse and the diurnal African striped mouse. Curiously,
molecular and neuronal activity rhythms in the SCN peak at similar times in diurnal and nocturnal animals. How
does an ostensibly identical SCN rhythm determine these dramatically different temporal niches? Our
approach will allow us to address this and other long-standing questions in chronobiology by identifying both
the mechanisms that temporally organize behaviors and the differences in molecular and neural function that
decide an animal’s temporal niche preference. Identifying the genes, neurons, and circuits that regulate the
timing of behavior in both laboratory mice and striped mice will also provide a novel framework for
understanding the biological basis of chronotype in humans and the etiology of circadian rhythm sleep
disorders. The discoveries we will make through our research program can generalize beyond circadian
biology to reveal fundamental mechanisms linking genes and circuits to behavior.

## Key facts

- **NIH application ID:** 11032284
- **Project number:** 3R35GM151020-01S1
- **Recipient organization:** TEXAS A&M UNIVERSITY
- **Principal Investigator:** JEFFREY R JONES
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $158,907
- **Award type:** 3
- **Project period:** 2023-08-01 → 2028-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11032284

## Citation

> US National Institutes of Health, RePORTER application 11032284, Circadian output mechanisms in nocturnal and diurnal animals (3R35GM151020-01S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/11032284. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*