# Cortical circuits for spectro-temporal integration of multi-frequency sounds

> **NIH NIH R01** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2022 · $14,248

## Abstract

PROJECT SUMMARY
In our daily life, even in the face of multiple sound sources, our brain binds together frequency components
that belong to the same source and recognizes individual sound objects. In humans, the integration of spectral
components into single sound perception relies on the precise synchrony of their onset timings, and this
grouping plays a critical role in our perception of language. In our ongoing parent grant (R01 DC017516), we
have identified the mouse secondary auditory cortex, A2, as a locus of multi-frequency integration, whose
synchrony-dependent sound responses mirror perceptual binding in humans. However, the circuit mechanisms
underlying how A2 neurons integrate information across parallel auditory channels to achieve coherent
perception remain unknown. Secondary sensory cortices are generally considered to receive pre-processed
inputs from the primary cortices. Interestingly, recent studies across sensory modalities suggest that secondary
cortices may also receive sensory inputs directly from the periphery, bypassing primary cortical areas. In the
auditory system, both a recent paper and our preliminary data showed that A2 receives direct inputs from the
primary auditory thalamus (ventral division of the medial geniculate nucleus: MGv). These results require
reconsideration of the sensory pathways that underlie the specialized functions of higher-order cortical areas.
In this proposed project, we will delineate the MGv-A2 ascending pathway using anatomical and
electrophysiological techniques to understand its contribution to the integrative function of A2 circuits. Our
specific goals aim to 1) identify the inferior colliculus subdivision upstream to the MGv-A2 pathway using tracer
injections and 2) determine the contribution of MGv inputs to A2 sound representations using optogenetics
during in vivo electrophysiological recordings. These aims will expand the scope of the parent study, which
focuses on the cortical circuits within A2 that integrate multi-frequency sounds. Dissection of the ascending
pathways that reach A2 will provide insights into the mechanisms that shape A2 sound representations and
provide a step towards understanding the “feature binding” circuits that enable verbal communication. Through
the proposed Post-baccalaureate Supplement, Ms. Michellee Garcia will work closely with her mentor, Dr.
Kato, to receive training in cutting-edge neuroscience techniques, auditory systems neuroscience, and
writing/communication skills. Ms. Garcia’s long-term goal is to join a neuroscience Ph.D. program and continue
her career in academia as an independent scientist. This supplement project will help her career development
by preparing her to pursue neuroscience research as a graduate student and beyond.

## Key facts

- **NIH application ID:** 10552385
- **Project number:** 3R01DC017516-03S1
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Hiroyuki Kato
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $14,248
- **Award type:** 3
- **Project period:** 2019-07-01 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10552385

## Citation

> US National Institutes of Health, RePORTER application 10552385, Cortical circuits for spectro-temporal integration of multi-frequency sounds (3R01DC017516-03S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10552385. Licensed CC0.

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