Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598148
Title: The development of motor coordination in Drosophila
Author: Crisp, S. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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Abstract:
We know little about how motor circuits are assembled to produce appropriately coordinated behaviours. Drosophila is an excellent system in which to investigate this topic. I therefore developed an imaging technique which enables contraction-relaxation cycles in individual muscles in intact, freely behaving embryos and larvae, to be visualised and documented for quantitative analysis. I have used this technique to document the ventral longitudinal muscle contractions in the embryo. I found that movement begins two thirds of the way through embryonic development. Embryos then go through a sequence of distinct phases, characterised by particular patterns of muscle contractions, before the first sequences resembling larval crawling emerge, some four hours after the first movements. Interestingly, the earliest movements in Drosophila embryos occur before neurons become capable of firing action potentials. I was able to prove that these movements are myogenic in origin. I next pinpointed when the transition to neurogenic movement occurs. Then, by disabling the sensory systems, I demonstrated that the onset of neurogenic movement is not a reflex response to sensory stimulation. On the other hand, I found evidence that spontaneous firing in the nervous system, as neurons acquire their electrical properties, could be responsible for the first neurally-driven muscle contractions. The first motor output in embryos is a disorganised burst of activity, which bears no resemblance to larval crawling. Over the next hour, I find that motor output occurs as repeated bursts, separated by log period of inactivity. Within these bursts increasingly coordinated patterns of muscle contractions are seen, eventually culminating in the first complete waves of peristaltic crawling. These bursts of activity, like the first motor output, do not require sensory input to occur. Instead, I find evidence that they are the consequence of a network which is spontaneously active and subject to activity-dependent depression. Intrinsic episodic activity of this kind is also a feature of maturing networks in vertebrates.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.598148  DOI: Not available
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