Study Results from University of Edinburgh Update Understanding of Physiology (Segmentation of the mouse fourth deep lumbrical muscle connectome reveals concentric organisation of motor units)
By a News Reporter-Staff News Editor at Life Science Weekly -- Investigators discuss new findings in Life Science Research. According to news reporting out of Edinburgh, United Kingdom, by NewsRx editors, research stated, "Connectomic analysis of the nervous system aims to discover and establish principles that underpin normal and abnormal neural connectivity and function. Here we performed image analysis of motor unit connectivity in the fourth deep lumbrical muscle (4DL) of mice, using transgenic expression of fluorescent protein in motor neurones as a morphological reporter."
Our news journalists obtained a quote from the research from the University of Edinburgh, "We developed a method that accelerated segmentation of confocal image projections of 4DL motor units, by applying high resolution (63 x , 1.4 NA objective) imaging or deconvolution only where either proved necessary, in order to resolve axon crossings that produced ambiguities in the correct assignment of axon terminals to identified motor units imaged at lower optical resolution (40 x , 1.3 NA). The 4DL muscles contained between 4 and 9 motor units and motor unit sizes ranged in distribution from 3 to 111 motor nerve terminals per unit. Several structural properties of the motor units were consistent with those reported in other muscles, including suboptimal wiring length and distribution of motor unit size. Surprisingly, however, small motor units were confined to a region of the muscle near the nerve entry point, whereas their larger counterparts were progressively more widely dispersed, suggesting a previously unrecognised form of segregated motor innervation in this muscle. We also found small but significant differences in variance of motor endplate length in motor units, which correlated weakly with their motor unit size. Thus, our connectomic analysis has revealed a pattern of concentric innervation that may perhaps also exist in other, cylindrical muscles that have not previously been thought to show segregated motor unit organisation."
According to the news editors, the research concluded: "This organisation may be the outcome of competition during postnatal development based on intrinsic neuronal differences in synaptic size or synaptic strength that generates a territorial hierarchy in motor unit size and disposition."
For more information on this research see: Segmentation of the mouse fourth deep lumbrical muscle connectome reveals concentric organisation of motor units. Journal of Physiology, 2013;591(Pt 19):4859-75. (Wiley-Blackwell - www.wiley.com/; Journal of Physiology - onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-7793)
Our news journalists report that additional information may be obtained by contacting T.C. Hirst, R R Ribchester: Euan Macdonald Centre for Motor Neurone Disease Research, Centre for Integrative Physiology, The University of Edinburgh, Edinburgh EH8 9XD, UK (see also Life Science Research).
Keywords for this news article include: Edinburgh, United Kingdom, Europe, Life Science Research.
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