# Influence of T-Stellate Cell Input on Sound Processing in the Inferior Colliculus

> **NIH NIH F31** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2024 · $42,555

## Abstract

Abstract: The inferior colliculus (IC) is the midbrain hub of the auditory system and is important for the
processing of speech and other vocalizations. T-stellate neurons provide the only direct projection from the
anteroventral cochlear nucleus (AVCN) to the IC and have been implicated in the processing of vocalization
cues since they encode information about sound frequency and amplitude modulations (AM). However, how T-
stellate cells influence specific populations of IC neurons and how they shape speech and vocalization coding
in the IC is unknown. One barrier to studying T-stellate input to the IC has been a lack of molecular markers for
IC neuron classes. Recently, we overcame this barrier by identifying two novel classes of IC neurons:
glutamatergic VIP neurons and GABAergic NPY neurons. Together, VIP and NPY neurons represent ~55-75%
of stellate cells within the central nucleus of the IC. Using channelrhodopsin assisted circuit mapping and
fluorescence-targeted whole cell recordings in brain slices, our preliminary data show that both VIP and NPY
neurons receive functional synaptic input from T-stellate cells. Interestingly, the excitatory postsynaptic
potentials (EPSPs) evoked by T-stellate input to NPY neurons are larger in amplitude than those evoked in VIP
neurons. In addition, optogenetic activation of T-stellate terminals can elicit feedforward inhibition in both NPY
and VIP neurons, suggesting that T-stellate afferents can recruit local inhibitory circuits in the IC. To investigate
how T-stellate cells influence frequency tuning and AM selectivity in the IC, we will make in-vivo single-unit
recordings from IC neurons before and after silencing T-stellate inputs using chemogenetics with the inhibitory
receptor hM4Di. In preliminary experiments, we have validated our chemogenetic approach by showing that
co-expression of hM4Di and the excitatory opsin Chronos in T-stellate cells enables us to reduce the amplitude
of light-evoked EPSPs in IC neurons with an hM4Di agonist. The overall objective of this proposal is to
determine differences in the prevalence, dynamics, and pharmacology of T-stellate cell inputs to NPY and VIP
neurons, and to determine how T-stellate input influences frequency tuning and AM coding in vivo. In Aim 1,
we will determine the prevalence, short-term plasticity, and receptor pharmacology of T-stellate input to NPY
and VIP neurons in vitro using whole cell recordings in IC slices. In Aim 2, we will determine how T-stellate
neurons shape frequency tuning and AM coding in the IC by selectively inhibiting T-stellate with
chemogenetics while recording from IC neurons. The expected results will provide direct evidence about how a
specific source of ascending input to the IC supports the processing of auditory cues that are important for
understanding speech and other vocalizations.

## Key facts

- **NIH application ID:** 10928744
- **Project number:** 5F31DC021618-02
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Yoani Natalie Herrera
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $42,555
- **Award type:** 5
- **Project period:** 2023-09-01 → 2027-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10928744

## Citation

> US National Institutes of Health, RePORTER application 10928744, Influence of T-Stellate Cell Input on Sound Processing in the Inferior Colliculus (5F31DC021618-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10928744. Licensed CC0.

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