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Proprioceptive input resets central locomotor rhythm in the spinal cat
B A Conway1, H Hultborn, O Kiehn
1Department of Neurophysiology, Panum Institute, University of Copenhagen, Denmark.
Experimental Brain Research
|January 1, 1987
Summary
Muscle proprioceptors, specifically from extensor muscles, can adjust the nervous system's rhythmic locomotion. This finding is crucial for understanding how the body adapts stepping to environmental changes.
Area of Science:
- Neuroscience
- Locomotion research
- Motor control
Background:
- The reflex regulation of stepping is vital for environmental adaptation.
- Muscle proprioceptors significantly influence centrally generated locomotor activity.
Purpose of the Study:
- To investigate the impact of muscle proprioceptors on fictive locomotion.
- To identify the specific afferent pathways involved in regulating step cycles.
Main Methods:
- Utilized decerebrate, unanesthetized cats with spinal transection.
- Induced fictive locomotion using nialamide and L-DOPA.
- Stimulated group I afferents from knee and ankle extensors and recorded motoneuron activity.
Main Results:
- Group I afferent stimulation from extensors reset fictive locomotion.
- Stimuli terminated flexor bursts and initiated extensor bursts, or prolonged extensor activity.
- Intracellular recordings showed premotoneuronal inhibition/excitation mediated the effects.
Conclusions:
- Extensor group I afferents access central rhythm generators, influencing stepping.
- Golgi tendon organ Ib afferents are the primary source of this input.
- Increased extensor load during stance prolongs extensor activity and delays swing phase initiation.