# Extratelencephalic contributions to auditory categorization

> **NIH NIH R01** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2024 · $82,567

## Abstract

Project Summary
Auditory-guided behavior is ubiquitous in everyday life, whenever auditory information is used to guide the
decisions we make and the actions we take. One such behavior is auditory categorization, a process that reflects
the ability to transform bottom-up sensory stimuli into discrete perceptual categories and use these perceptual
categories to drive a subsequent action. Although this process is well-documented at the behavioral and
cognitive levels, surprisingly little is known about the explicit neural circuit mechanisms that underlie categorical
computation and how the result of this computation drives behavioral outcomes.
We believe that the transformation of auditory information into an appropriate behavioral response is necessarily
a brain-wide endeavor. The deep layers of the auditory cortex give rise to several massive projection systems
that exert influence over many downstream brain areas. Of these, extratelencephalic (ET) neurons within layer
5b have long been regarded as canonical “broadcast” neurons, pooling inputs from a variety of sources and
transmitting signals throughout the brain. These neurons are unique in that they provide the only direct
connection between the neocortex and various behaviorally relevant subcortical structures, placing them in a
privileged position where they can readily influence auditory-guided behavior.
To understand the role that ET neurons play in auditory-guided behavior necessitates in vivo, cell-type specific
recordings, in awake behaving animals. To this end, we have designed a novel auditory categorization task that
can be readily learned by head-fixed mice. Our preliminary data, both anatomical and physiological, posits that
ET neurons become selective to discrete perceptual categories across learning, and this selectivity is mediated
by top-down input from higher-order cortex. The goal of this proposal is to leverage cutting-edge techniques to
test three specific hypotheses: (1) ET neurons are necessary for auditory categorization, and this necessity is
both learning-dependent and specific to distinct axon collaterals (Aim 1), (2) ET response properties change
across learning to reflect discrete perceptual categories (Aim 2), and (3) ET learned categorical selectivity is
shaped via top-down inputs from higher-order cortex that act as a flexible, task-dependent filter (Aim 3).
Combined, this research will take an important first step towards understanding the role of descending circuits
in auditory-guided behavior will unveil the greater auditory pathway that lies beyond its classical terminus in
primary auditory cortex.

## Key facts

- **NIH application ID:** 10952149
- **Project number:** 3R01DC020459-03S1
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** Ross Stewart Williamson
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $82,567
- **Award type:** 3
- **Project period:** 2022-06-10 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10952149

## Citation

> US National Institutes of Health, RePORTER application 10952149, Extratelencephalic contributions to auditory categorization (3R01DC020459-03S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10952149. Licensed CC0.

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