Dissertation
Intrinsic properties and connectivity of Shox2 interneurons in spinal locomotor networks
Doctor of Philosophy (Ph.D.), Drexel University
Nov 2019
DOI:
https://doi.org/10.17918/v1ww-9n74
Abstract
Hindlimb locomotion or walking is a highly stereotypical and coordinated activity that is characterized by alternation in flexor and extensor muscles on the same side of the body and alternation of the same muscle types on the opposite side of the body. This behavior is generated by a specialized neural network called the central pattern generator, located in the thoracolumbar region of the spinal cord. Among others, spinal central pattern generator consists of rhythm generating interneurons that are capable of generating the rhythm (or timing), and recruiting neurons controlling the pattern of muscle activation. The mechanisms contributing to rhythmogenesis in rhythm generating interneurons have been hypothesized but are still largely unknown. Spinal interneurons expressing the transcription factor Shox2 have recently been demonstrated to participate in locomotor rhythm generation and patterning. The purpose of this thesis is to explore cellular properties and interconnectivity of Shox2 interneurons as two potential mechanisms contributing to their rhythmic activity in neonatal mice. Connectivity studies revealed that Shox2 interneurons are connected primarily via electrical synapses, which function to promote synchrony in population activity. Electrical coupling is specific to functional rhythm and patterning populations. Shox2 interneurons can also be divided into flexor- or extensor-related neurons based on the locomotor phasing of their firing. Interconnectivity was also found to be specific to flexor- and to extensor-related Shox2 populations. Intrinsic properties and potential rhythmogenic currents were similarly expressed in Shox2 neurons, regardless of functional grouping. Altogether, our findings providing insight into the organization of the spinal locomotor network by suggesting that network properties and interconnectivity may play a more prominent role in contributing to rhythmic activity in Shox2 interneurons in neonatal mice.
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Details
- Title
- Intrinsic properties and connectivity of Shox2 interneurons in spinal locomotor networks
- Creators
- Ngoc T. B. Ha - DU
- Contributors
- Wen-jun Gao (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- x, 152 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Medicine; Neurology; Drexel University
- Other Identifier
- 11347; 991014632430304721