Cochlear neural degeneration disrupts hearing in background noise by increasing auditory cortex internal noise.

Summary

Cochlear neural degeneration (CND) in adult mice caused selective difficulty detecting sounds in background noise. Two-photon imaging of layer 2/3 PV interneurons and pyramidal cells revealed plasticity that culminated in net cortical hyperactivity, higher gain, and reduced adaptation to noise, an internal cortical 'noise' that predicted perceptual failures.

Key findings

• CND causes behavioral detection deficits specifically in background noise.
• Distinct plasticity in excitatory vs. PV inhibitory neurons yields net cortical hyperactivity and increased gain.
• Surges of hypercorrelated cortical activity before target onset predict impending detection failures.
• Establishes internal cortical noise as a central determinant of a peripheral hearing disorder.