# Population coding of complex auditory stimuli in auditory cortex

> **NIH NIH F31** · JOHNS HOPKINS UNIVERSITY · 2024 · $48,974

## Abstract

Project Summary
The processing and categorization of complex sounds is a skill critical to interacting with one’s environment for
many animals, the disruption of which can negatively affect quality of life for individuals suffering from auditory
processing disorders. Despite this importance, the processing and categorization of complex auditory stimuli
have yet to be fully understood. Existing work largely investigates the encoding of pure tone stimuli, which are
scarce in nature and not behaviorally relevant for most animals. Moreover, few studies have attempted to
prove causal relationships between neural activity correlated with stimulus presentation, and perception of a
given sound. Some such studies have shown improvements in behavior following optogenetic activation
strategies that stimulate broad subfields of auditory cortex; however, these strategies have been too spatially
coarse to interrogate the precise circuitry underlying encoding of stimuli. In this project we thus propose to
investigate the neural circuitry involved in categorization of auditory stimuli in mice performing a two-alternative
forced choice (2AFC) discrimination task, at three different levels along the auditory cortical pathway. We will
examine auditory cortical population dynamics first during categorization of unfamiliar pure tones (intermediate
between trained categories), identifying networks using Granger causality analysis and probing causality using
holographic stimulation. Given the importance of stimulus identity in 2AFC tasks, we expect to identify GC
subnetworks that show an overrepresentation of cells tuned to the frequencies of trained stimuli, and expect
that stimulation of strongly linked cells during presentation of intermediate stimuli will bias behavioral response
towards the category associated with activity of those cells. We will subsequently examine network dynamics
during presentation of more behaviorally relevant harmonic stimuli. Although harmonic structure has been
shown to be necessary for perception of vocalizations by mice, the processing of periodicity by the mouse
auditory system remains poorly understood. We hypothesize that primary auditory cortex (A1) layer 4 (L4) cells
tuned to the components of harmonics carry stimulus information to harmonicity-sensitive cells in layer 2/3,
which in turn is passed to cells sensitive to category membership as well as to periodicity-sensitive cells in
secondary auditory cortex. We expect this work to lead to a more complete picture of the processing of
harmonic sounds along the cortical hierarchy, as well as shed light on the neural encoding of categories
through examination of the causal relationship between ensemble activity and behavior.

## Key facts

- **NIH application ID:** 11071254
- **Project number:** 1F31DC022515-01
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Jade Daher
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $48,974
- **Award type:** 1
- **Project period:** 2024-09-01 → 2027-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11071254

## Citation

> US National Institutes of Health, RePORTER application 11071254, Population coding of complex auditory stimuli in auditory cortex (1F31DC022515-01). Retrieved via AI Analytics 2026-05-31 from https://api.ai-analytics.org/grant/nih/11071254. Licensed CC0.

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