Interlimb coordination during fictive locomotion in the thalamic cat

Area of Science:

• Neuroscience
• Locomotion Control
• Motor Systems

Background:

• Understanding interlimb coordination is crucial for deciphering motor control.
• The role of central pattern generators (CPGs) in locomotion is a key area of research.
• Spinal cord circuits are known to generate rhythmic motor activity for stepping.

Purpose of the Study:

• To investigate how the central nervous system (CNS) controls interlimb coordination during locomotion.
• To determine the temporal and phase relationships between fictive stepping cycles of different limb pairs.
• To identify distinct patterns of interlimb coordination during spontaneous fictive locomotion.

Main Methods:

• Recorded efferent nerve discharges from muscles in all four limbs of thalamic cats.
• Simultaneously analyzed spontaneous fictive locomotion.
• Determined temporal and phase relationships of fictive step cycles using flexor muscle burst onsets.

Main Results:

• Strict alternation observed between forelimb fictive step cycles.
• Phasing of hindlimb, homolateral, and diagonal limb step cycles showed variability.
• Identified frequent coordination patterns mirroring walking and trotting gaits, suggesting CNS control independent of peripheral input.

Conclusions:

• The CNS can generate most interlimb coordination patterns observed in real locomotion without peripheral sensory input.
• Fictive locomotion studies reveal the intrinsic capabilities of the nervous system for generating complex motor behaviors.
• Results support the hypothesis of diagonal interactions between forelimb and hindlimb CPGs for interlimb coordination.