Locomotion in intact and in brain cortex-ablated cats

Area of Science:

• Neuroscience
• Motor Control Research
• Animal Models in Physiology

Background:

• Existing decerebration methods incompletely isolate motor control pathways.
• Decortication removes the cortex but leaves subcortical regions, creating a gap in understanding motor control.
• The thalamus's role in motor control remains partially unexplored due to current preparation limitations.

Purpose of the Study:

• To introduce and characterize a novel animal preparation, the Brain Cortex-Ablated Cat (BCAC).
• To investigate the impact of ablating the frontal and parietal cortices on hindlimb motor control during locomotion.
• To assess the role of the thalamus and subcortical structures in motor control and cutaneous reflexes.

Main Methods:

• Development of the Brain Cortex-Ablated Cat (BCAC) preparation, involving removal of frontal/parietal cortices and underlying white matter.
• Analysis of hindlimb electromyograms (EMG) and kinematics during locomotion in both intact and BCAC cats.
• Evaluation of cutaneous reflexes (CR) elicited by electrical stimulation of the sural or saphenous nerves in both preparations.

Main Results:

• BCAC cats exhibited increased flexor and decreased extensor hindlimb EMG amplitudes compared to intact cats.
• Bifunctional muscle EMGs showed complex, speed-dependent amplitude variations in BCAC.
• Cutaneous reflexes were largely absent in BCAC, though some reappeared at higher locomotion speeds.

Conclusions:

• The BCAC preparation allows for suprathalamic decerebration, preserving thalamic function.
• Subcortical locomotor networks in BCAC cats partially compensate for cortical ablation, enabling near-normal locomotion.
• This model offers new insights into the subcortical control of locomotion and sensory-motor integration.