About this Research Topic
Propriospinal neurons are contained entirely within the spinal cord and may have short segmental or multi-segment projections. Propriospinal neurons serve to convey a multitude of supraspinal descending commands and aid in the integration of these commands with sensory feedback from the body. They also serve to mediate and coordinate rhythmic motor output involving multiple joints and neurons across several spinal segments. Groups of propriospinal neurons constitute essential building blocks of the central pattern generators (CPGs) for respiration, locomotion and autonomic functions.
Given their complexity and diverse functions, how might we dissect these propriospinal circuits? Functional groups of propriospinal neurons have been identified based on input-output properties, their action potentials during reflex- or supraspinally-generated motor output, and by genetic markers. Connectivity mapping of propriospinal cells to other neurons and functional studies verifying the recruitment of propriospinal cells while measuring motor, sensory or autonomic output are also important for understanding propriospinal circuits. Projections of propriospinal cells to spinal motoneurons are extensive and they provide a large proportion of the excitatory and inhibitory inputs that the motoneurons receive. Consequently, propriospinal neurons are in a powerful position to influence the excitation of motoneurons both in health and disease. It is therefore not surprising that imbalances in this circuitry may play an excitotoxic role in diseases, for example in Amyotrophic Lateral Sclerosis.
Several researchers investigating functional recovery after spinal cord injury have recognized the essential contribution of activating propriospinal networks to enhance recovery of locomotion. After injury to neurons of the brain as during stroke, motor function recovery and plasticity can also be boosted by propriospinal neural activation. This highlights the unique potential of propriospinal neurons as novel therapeutic targets to modulate disease processes and expedite functional recovery. Combinatorial therapeutic approaches targeting propriospinal networks need to be recognized and developed for maximizing recovery after spinal cord injury and also in the case of other diseases affecting neural function.
This Research Topic on propriospinal neurons welcomes all submissions of original research papers, short communications or reviews involving:
1) Identification and characterization of identified propriospinal neuron populations
2) Plasticity of propriospinal neurons in spinal injury and disease
3) Functional characterization of propriospinal networks
4) Integration between locomotor and autonomic propriospinal networks
Keywords: spinal cord, plasticity, locomotion, respiration, autonomic functions
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