# Modulation of sensory representations in the auditory cortex by callosal inputs

> **NIH NIH F32** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2020 · $29,513

## Abstract

ProjectAbstract
 Interhemispheric (callosal) connections between the right and left auditory cortex
are suggested to participate in sound localization and speech processing. Furthermore,
pathophysiology of auditory callosal projections is proposed to underlie language
deficits and auditory hallucinations associated with brain disease. Despite the potential
importance of cortical callosal projections in auditory processing, the functional
properties of interhemispheric connections are not well understood. Here, we use
optogenetic, electrophysiological and imaging approaches in awake, head-fixed mice to
determine how callosal projections contribute to sensory coding in primary auditory
cortex (A1). Initial anatomical and physiological experiments in brain slices will
determine the layer and cell type specificity of callosal inputs. Next, acute and reversible
optogenetic silencing of the left auditory cortex combined with linear silicon probe
recordings in A1 of the right cortex in awake, head fixed mice will establish how one
cortex influences tone-evoked responses in the other. Finally, we will use in vivo two-
photon calcium imaging to determine the tonotopic organization of callosal projections
and whether it is similar to the tonotopic gradient of target regions. Completion of this
work will lend insight into the function of the interhemispheric callosal pathway in the
auditory system and will shed light on the mechanisms it uses to modulate sensory
representations. A deeper understanding of this pathway will inform the diagnosis and
treatment of patients with communication disorders, where the callosum is impacted, in
diseases such as multiple sclerosis, schizophrenia, and autism.
Hypothesis: Callosal inputs modulate auditory sensory representations in a tonotopic,
layer and cell type specific manner.
Aim 1. Determine the anatomical distribution of callosal projections and their impact on
local circuits in slices of primary auditory cortex.
Aim 2. Determine the role of callosal input in primary auditory cortex in awake mice.
Aim 3. Define the frequency response properties and tonotopic organization of axonal
boutons originating from callosal projections in awake mice using two-photon calcium
imaging.

## Key facts

- **NIH application ID:** 9852880
- **Project number:** 5F32DC017906-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** Bernard Slater
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $29,513
- **Award type:** 5
- **Project period:** 2019-04-01 → 2020-09-29

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9852880

## Citation

> US National Institutes of Health, RePORTER application 9852880, Modulation of sensory representations in the auditory cortex by callosal inputs (5F32DC017906-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9852880. Licensed CC0.

---

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