Offset Responses in the Auditory Cortex Show Unique History Dependence.

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Sensory Processing

Background:

• Sensory neuron responses are influenced by recent stimulus history, crucial for adaptation and efficient coding.
• Auditory cortex (AC) neurons exhibit well-characterized history dependence for sound-evoked onset responses.
• The history dependence of sound termination (offset) responses in the AC remains largely unexplored.

Purpose of the Study:

• To investigate the history dependence of auditory offset responses.
• To compare the dynamics of onset and offset responses in the AC.
• To examine how these dynamics are distributed across different auditory neuron types.

Main Methods:

• Recorded single-unit activity in the primary auditory cortex of awake mice.
• Presented repeating noise burst stimuli to evoke onset and offset responses.
• Used optotagging to identify parvalbumin and somatostatin interneurons.
• Classified units as narrow-spiking or broad-spiking.

Main Results:

• Offset responses were generally less depressive than onset responses across various stimulus parameters.
• A cell's onset response characteristic (facilitatory or depressive) did not predict its offset response characteristic.
• Cell types showed differences in onset response dynamics and the prevalence of offset responses, but not in offset response dynamics.
• Clustering of spiking responses revealed associations with cell types, with some cell type-specific dynamics observed even within clusters.

Conclusions:

• Onset and offset responses in the auditory cortex are differentially modulated by recent sound history.
• Offset responses exhibit unique dynamics, being more facilitatory and less dependent on cell type compared to onset responses.
• These distinct properties suggest specialized functional roles for encoding sound cessation in the auditory system.