Offset responses in primary auditory cortex are enhanced after notched noise stimulation.

Area of Science:

• Neuroscience
• Auditory Perception
• Sensory Processing

Background:

• Sensory aftereffects are illusions arising from prolonged sensory stimulation.
• The Zwicker tone (ZT) is an auditory aftereffect linked to tinnitus, triggered by notched noise (NN).
• Mechanisms of ZT and NN effects on the central auditory system remain poorly understood.

Purpose of the Study:

• Investigate the neural activity in the auditory cortex during and after NN stimulation.
• Analyze the laminar structure of neural responses to NN.
• Explore the link between NN-induced responses and the Zwicker tone.

Main Methods:

• Recorded neural activity (spiking and local field potentials) in the guinea pig auditory cortex.
• Utilized white noise (WN) and notched noise (NN) stimulation in anesthetized and awake animals.
• Performed current source density analysis to map neural activity.

Main Results:

• NN stimulation caused significantly increased offset responses compared to WN.
• Offset responses were concentrated in the granular and upper infragranular layers.
• Responses were strongest when neuronal best frequency matched the NN's missing band.

Conclusions:

• NN elicits prominent excitatory offset responses in the auditory cortex.
• These responses, particularly in specific layers, may underlie the Zwicker tone percept.
• Findings provide insights into sensory deprivation effects and potential tinnitus models.