Auditory Corticothalamic Neurons Are Recruited by Motor Preparatory Inputs

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Sensory Processing

Background:

• Corticothalamic (CT) neurons form a major descending sensory pathway, but their precise function is unclear.
• Layer 6 (L6) CT neurons' role in sensory processing, particularly auditory, requires further investigation.

Purpose of the Study:

• To test if L6 CT neurons activate due to extra-sensory inputs preceding anticipated sounds.
• To explore the contribution of L6 CT neurons to active sensing and motor modulation of auditory input.

Main Methods:

• Optogenetically targeted single-unit recordings and two-photon imaging of Ntsr1-Cre+ L6 CT neurons in the primary auditory cortex (A1) of mice.
• Mice performed an active listening task involving sound presentation and reward.
• Monosynaptic input tracing using rabies virus in A1 L6 CT neurons.

Main Results:

• L6 CT neurons and other L6 units exhibited spiking activity preceding orofacial movements linked to sound and reward.
• This pre-movement activity was specific to task-related movements, not general locomotion.
• Cholinergic and non-cholinergic projection neurons in the external globus pallidus were identified as potential monosynaptic inputs to A1 L6 CT neurons.

Conclusions:

• L6 CT neurons are activated by motor-related inputs prior to anticipated auditory stimuli and associated movements.
• New pathways for motor modulation of sound processing involving the external globus pallidus and L6 CT neurons are identified.
• CT neurons may play a significant role in active sensing, integrating motor commands with sensory information.