# Top-down mechanisms underlying contextual and adaptive processing in the auditory system

> **NIH NIH K99** · UNIVERSITY OF PENNSYLVANIA · 2024 · $137,305

## Abstract

PROJECT SUMMARY
Sensory environments are cluttered and dynamic, with salient features 1) often masked or degraded by other
stimuli and 2) capable of holding multiple meanings depending on the surrounding context. To account for this
variability, sensory systems must process information in an adaptive manner by using contextual cues and prior
information to bias incoming sensory information. Though this flexibility is critical for accurate sensory
processing, the mechanisms underlying adaptive processing remain poorly understood. Descending projections
from hierarchically higher brain regions to lower regions are a hypothesized anatomical substrate for top-down
modulation of incoming sensory information. In the central auditory system, descending connections from the
auditory cortex target numerous subcortical structures and these cortico-fugal pathways have been implicated
in top-down processes such as predictive coding and attentional modulation of speech in noise. Specifically,
projections from the auditory cortex have been found to carry contextual information about sound statistics to
the auditory midbrain, or inferior colliculus, and to enhance responses to degraded sounds in the auditory
thalamus, or medial geniculate body. Though these cortico-fugal pathways have been implicated in contextual
processing and perceptual adaptation to degraded sounds, the broader circuit and physiological mechanisms
underlying these phenomena remain unknown. Therefore, the goal of this proposal is to 1) determine the
mechanisms by which cortico-fugal neurons enable contextual processing, with the hypothesis that they induce
receptive field plasticity in IC neurons, 2) determine if top-down inputs alter context-dependent network
reorganization, and 3) test how top-down circuits mediate adaptation to challenging listening conditions at the
physiological and network level. This proposal uses a combination of behavior, large-scale electrophysiology,
two-photon calcium imaging, optogenetics, and network analysis methods to address these aims. The results of
these studies will reveal the circuit and physiological mechanisms underlying auditory contextual processing and
perceptual adaptation. The impact of these experiments extends beyond the auditory system, as it may reveal
generalizable principles about adaptive processing and behavior.

## Key facts

- **NIH application ID:** 10986454
- **Project number:** 1K99DC021582-01A1
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Alexandria Marie Lesicko
- **Activity code:** K99 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $137,305
- **Award type:** 1
- **Project period:** 2024-07-01 → 2027-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10986454

## Citation

> US National Institutes of Health, RePORTER application 10986454, Top-down mechanisms underlying contextual and adaptive processing in the auditory system (1K99DC021582-01A1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10986454. Licensed CC0.

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