Mind the Gap: Two Dissociable Mechanisms of Temporal Processing in the Auditory System

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Sensory Processing

Background:

• High temporal acuity is vital for processing speech and rapid sounds.
• Gap-detection deficits are linked to sluggish auditory processing and developmental disorders.
• Current understanding often assumes general temporal processing impairment.

Purpose of the Study:

• To investigate auditory brain sensitivity to brief gaps in noise in a mouse model.
• To determine if deficits are specific to gap detection or reflect general temporal acuity loss.
• To identify neural mechanisms underlying gap-detection deficits in the auditory thalamus.

Main Methods:

• Extracellular recordings in subdivisions of the auditory thalamus in anesthetized mice.
• Stimulus presentation included brief gaps in noise and other rapidly changing sounds.
• Experimental and computational modeling were used to analyze neural population activity.

Main Results:

• A stimulus-specific and subdivision-specific deficit in thalamic sensitivity to brief gaps in noise was observed.
• Reduced neural responses to gaps were found in lemniscal and nonlemniscal medial geniculate body subdivisions.
• Deficits arose from reduced neural activity following noise offsets, not onsets.

Conclusions:

• Auditory processing involves dissociable sound-onset-sensitive and sound-offset-sensitive channels.
• Gap-detection deficits can result from specific impairment of sound-offset-sensitive pathways.
• This challenges the notion of solely "sluggish" auditory processing and points to specific neural channel dysfunction.