Descending pathways in motor control.

@article{Lemon2008DescendingPI,
  title={Descending pathways in motor control.},
  author={Roger Lemon},
  journal={Annual review of neuroscience},
  year={2008},
  volume={31},
  pages={
          195-218
        }
}
  • R. Lemon
  • Published 17 June 2008
  • Biology, Psychology
  • Annual review of neuroscience
Each of the descending pathways involved in motor control has a number of anatomical, molecular, pharmacological, and neuroinformatic characteristics. They are differentially involved in motor control, a process that results from operations involving the entire motor network rather than from the brain commanding the spinal cord. A given pathway can have many functional roles. This review explores to what extent descending pathways are highly conserved across species and concludes that there are… 

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References

SHOWING 1-10 OF 140 REFERENCES
Neural mechanisms underlying corticospinal and rubrospinal control of limb movements.
Spinal cord pattern generators for locomotion
  • V. Dietz
  • Biology, Psychology
    Clinical Neurophysiology
  • 2003
Comparing the function of the corticospinal system in different species: Organizational differences for motor specialization?
TLDR
Two critical functions of the corticospinal tract are discussed: first, the role of descending projections to the dorsal horn in the control of sensory afferent input, and second, the capacity of direct cortico‐motoneuronal projections to support voluntary execution of skilled hand and finger movements.
Locomotor role of the corticoreticular-reticulospinal-spinal interneuronal system.
Red nucleus projections to distinct motor neuron pools in the rat spinal cord
TLDR
A specific, preferential role of the RST in distal forelimb muscle control is supported, and rubrospinal axons were seen in close apposition to the distal and intermediate muscle motoneurons, but were consistently absent in the most ventrally situated motor column projecting to proximal muscles.
PRIMARY MOTOR CORTEX INFLUENCES ON THE DESCENDING AND ASCENDING SYSTEMS
Cortical and brainstem control of locomotion.
The complex structure of a simple memory
Striking differences in transmission of corticospinal excitation to upper limb motoneurons in two primate species.
TLDR
The results suggest that in primates with more advanced hand function, the CM system effectively replaces PN-mediated control, and the positive correlation across species between moreadvanced hand function and the strength of theCM system is accompanied by a negative correlation between hand functions and thestrength of the PN system.
...
...