Hierarchical Deviant Processing in Auditory Cortex of Awake Mice.

Area of Science:

• Neuroscience
• Auditory Processing
• Sensory Perception

Background:

• Detecting environmental patterns and changes is crucial for sensory processing.
• Auditory system studies show adaptation and prediction error responses are dissociable.
• Previous research often used simple stimuli (e.g., pure tones) lacking ecological validity.

Approach:

• Investigated auditory cortical activity in awake mice (N=8) using wide-field calcium imaging.
• Utilized an auditory oddball paradigm with complex sound patterns (bisyllabic pairs).
• Compared neural responses to single stimulus probability violations versus complex order-based violations.

Key Points:

• Auditory cortex (ACtx) responses were sensitive to both single stimulus probability and global pattern violations.
• Both substitution and transposition deviants elicited mismatch signals.
• Area A2 showed stronger mismatch signaling than primary auditory cortex (A1) for complex violations.

Conclusions:

• A hierarchical gradient of prediction error signaling exists in the auditory cortex.
• This hierarchy, particularly for late neural response peaks, reflects processing of complex sensory pattern violations.
• Findings suggest late-stage auditory cortex activity is vital for predicting and responding to intricate auditory sequences.