Corticothalamic communication for action coordination in a skilled motor behavior.

Area of Science:

• Neuroscience
• Motor Control
• Systems Neuroscience

Background:

• Coordinating forelimb and orofacial movements for behaviors like feeding requires complex neural communication across brain regions.
• Understanding the specific neural circuits involved in skilled motor behaviors is crucial for deciphering brain function.

Purpose of the Study:

• To identify the cortical network coordinating action progression in a mouse reach-and-withdraw-to-drink (RWD) behavior.
• To investigate the differential roles of specific projection neuron types and output channels within the secondary motor cortex (MOs-c).

Main Methods:

• Wide-field imaging and photoinhibition across the cortex to survey neural activity.
• Electrophysiology and targeted photoinhibition within the MOs-c to study projection neuron types.
• Analysis of reach-and-withdraw-to-drink (RWD) behavior in mice.

Main Results:

• A specific cortical network, including the MOs-c, was identified as coordinating RWD behavior progression.
• Corticothalamic (CT^MOs) output channels, but not pyramidal tract channels, showed differential contributions to action progression and hand-mouth coordination.
• CT^MOs neurons exhibited sustained firing during RWD actions and selectively enhanced activity in postsynaptic thalamus neurons, which also contribute to action coordination.

Conclusions:

• The motor cortex CT channel plays a selective role in amplifying thalamic integration of sensorimotor information.
• This amplification is critical for coordinating skilled motor behaviors by integrating cortical and subcortical inputs.
• The identified CT^MOs-thalamus pathway is a key component for coordinating complex, ethological motor actions.