Myelin Supports Cortical Circuit Function Underlying Skilled Movement

Area of Science:

• Neuroscience
• Motor Control
• Myelination Biology

Background:

• The primary motor cortex (M1) is crucial for skilled movement and heavily myelinated.
• Myelin loss, as seen in multiple sclerosis, causes motor impairment.
• The precise role of myelination in M1 neuronal activity during skilled behavior is not fully understood.

Purpose of the Study:

• To investigate how myelination influences neuronal activity and synchrony in M1 during dexterous reaching.
• To identify the cellular and circuit mechanisms linking myelin loss to motor deficits.

Main Methods:

• Combined in vivo imaging of oligodendrocytes with high-density Neuropixels recordings in mice during reaching tasks.
• Induced demyelination using cuprizone.
• Utilized a computational model constrained by experimental data.

Main Results:

• Cuprizone-induced demyelination impaired movement efficiency and altered cell-type-specific neuronal activity and synchrony.
• Identified inhibitory axonal propagation failures as a mechanism linking myelin loss to altered circuit function.
• Partial remyelination improved network metrics and reach consistency but not smooth movement, indicating selective vulnerability in inhibitory circuits.

Conclusions:

• Myelination is critical for supporting cortical circuit dynamics essential for skilled motor behavior.
• Inhibitory circuits show selective vulnerability to myelin loss, impacting motor control.
• These findings bridge cellular demyelination models with clinical motor impairments.