Excitatory and inhibitory crossed reflex pathways in mice

Area of Science:

• Neuroscience
• Motor Control
• Spinal Cord Reflexes

Background:

• Crossed reflexes, where sensory input from one limb affects the other, are well-documented in cats and humans.
• Previous studies in mice detailed commissural pathways using various physiological and genetic techniques.
• The direct link between mouse commissural pathways and crossed reflex pathways in other species remained unclear.

Purpose of the Study:

• To analyze crossed reflex pathways in mice using in vivo methods.
• To provide a detailed description of both excitatory and inhibitory crossed reflex pathways.
• To investigate the modulation of these pathways during locomotion.

Main Methods:

• In vivo electromyographic (EMG) recording techniques in mice.
• Peripheral nerve stimulation protocols.
• Analysis of reflex responses during resting and locomotion.

Main Results:

• Excitatory crossed reflexes are activated by both proprioceptive and cutaneous afferent inputs.
• A short-latency inhibitory crossed reflex pathway, likely mediated by cutaneous feedback, was identified.
• This short-latency crossed inhibition is reduced in knee extensor and ankle flexor muscles during walking.

Conclusions:

• This study provides the first in vivo characterization of excitatory and inhibitory crossed reflex pathways in the mouse spinal cord.
• The findings reveal that inhibitory crossed reflexes are modulated during locomotion.
• This research establishes a foundation for future genetic studies on crossed reflexes in mice.