# Mapping cerebellar granule cell function with novel genetic and optical tools

> **NIH NIH F32** · PRINCETON UNIVERSITY · 2020 · $70,310

## Abstract

Project Summary/Abstract
Recent evidence from multiple laboratories in both human and animal models supports a role for the granule cell (GrC)
pathway of the cerebellum in representing a wide range of sensory, motor, and internal information. Classical theories of
cerebellar function proposed that activity in a small number of GrCs (<1%) encodes a particular sensorimotor context.
However, recent population level calcium imaging studies of GrC somata indicate that populations of GrCs encode
sensory and motor events, and complex properties such as reward and motor preparation. However, these studies lacked
the temporal resolution to identify specific relationships between those events and GrC firing. Both study designs also
precluded direct determination of what input pathways drove the observed patterns of GrC activity. A comprehensive
understanding of the input-output transform performed by GrCs will require the ability to precisely perturb anatomically
specific descending inputs while densely recording the resultant patterns of activity with high spatiotemporal precision.
To approach this set of methodological gaps, I propose to (1) holistically develop a spike-counting method for genetically
encoded indicators (GECIs) by adjusting current sensor properties and creating a biophysical in vivo model of the calcium
sensor GCaMP, (2) optogenetically perturb neocortex to map its functional inputs to GrCs while optically accessing the
entire cerebellar surface, and (3) use a rodent behavioral task to disambiguate sensory, motor and internal-state
contributions to granule cell activity patterns. Completion of these aims will allow a direct test of whether GrCs indeed
make a sparse representation of their input signals. I also aim to provide the most comprehensive analysis to date on the
makeup of the inputs that drive GrC activity.

## Key facts

- **NIH application ID:** 10001987
- **Project number:** 5F32MH120887-02
- **Recipient organization:** PRINCETON UNIVERSITY
- **Principal Investigator:** Gerard Joey Broussard
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $70,310
- **Award type:** 5
- **Project period:** 2019-09-17 → 2022-09-16

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10001987

## Citation

> US National Institutes of Health, RePORTER application 10001987, Mapping cerebellar granule cell function with novel genetic and optical tools (5F32MH120887-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10001987. Licensed CC0.

---

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