INTRINSIC PROPERTIES OF LARVAL DROSOPHILA MOTONEURONS AND THEIR CONTRIBUTION TO MOTONEURON RECRUITMENT AND FIRING BEHAVIOR DURING FICTIVE LOCOMOTION

Persistent Link:
http://hdl.handle.net/10150/194655
Title:
INTRINSIC PROPERTIES OF LARVAL DROSOPHILA MOTONEURONS AND THEIR CONTRIBUTION TO MOTONEURON RECRUITMENT AND FIRING BEHAVIOR DURING FICTIVE LOCOMOTION
Author:
Schaefer, Jennifer
Issue Date:
2010
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Locomotion is controlled in large part by neural circuits (CPGs) that generate rhythmic stereotyped outputs in the absence of descending or sensory inputs. The output of a neural circuit is determined by the configuration of the circuit, synapse properties, and the intrinsic properties of component neurons. In order to understand how a neural circuit functions component neurons, their connections, and their intrinsic properties must be characterized. Motoneurons are a useful cell in which to begin investigation of CPG function because they are accessible and provide a measure of the cumulative activity of the circuit. Drosophila is a potentially useful model system for the study of motoneuron intrinsic properties, their contribution to locomotion, and of locomotor CPGs because the genetic and molecular techniques available in Drosophila are surpassed in no other organism and because the Drosophila nervous system is small in comparison to vertebrate nervous systems. Further, whole-cell in situ patch clamp recordings from adult and larval motoneurons in relatively intact preparations are possible. Therefore, the first goal of this work was to investigate whether the firing behavior and recruitment of identified Drosophila 1b and 1s motoneurons is analogous to the recruitment of high-threshold, phasic and low-threshold, tonic motoneurons in other organisms. The second goal was to determine whether active conductances influence motoneuron recruitment in response to synaptic input. The final aim was to investigate how these factors influence CPG output to muscles. Findings from current clamp studies indicate that1b motoneurons are more easily recruited than 1s motoneurons, in agreement with the hypothesis that 1b motoneurons are analogous to low-threshold motoneurons described in other organisms. Further, orderly recruitment of Drosophila 1b motoneurons before 1s motoneurons is not a result of passive properties. Instead, the Shal channel that encodes a large portion of IA in motoneuron somatodendritic regions is a critical determinant of delay-to-spike in larval Drosophila motoneurons. These findings are behaviorally-relevant because the same recruitment order is seen in simultaneous recordings from motoneuron pairs recruited by synaptic input.
Type:
text; Electronic Dissertation
Keywords:
Drosophila; excitability; motor neuron; recruitment
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Physiological Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Levine, Richard B.
Committee Chair:
Levine, Richard B.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleINTRINSIC PROPERTIES OF LARVAL DROSOPHILA MOTONEURONS AND THEIR CONTRIBUTION TO MOTONEURON RECRUITMENT AND FIRING BEHAVIOR DURING FICTIVE LOCOMOTIONen_US
dc.creatorSchaefer, Jenniferen_US
dc.contributor.authorSchaefer, Jenniferen_US
dc.date.issued2010en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractLocomotion is controlled in large part by neural circuits (CPGs) that generate rhythmic stereotyped outputs in the absence of descending or sensory inputs. The output of a neural circuit is determined by the configuration of the circuit, synapse properties, and the intrinsic properties of component neurons. In order to understand how a neural circuit functions component neurons, their connections, and their intrinsic properties must be characterized. Motoneurons are a useful cell in which to begin investigation of CPG function because they are accessible and provide a measure of the cumulative activity of the circuit. Drosophila is a potentially useful model system for the study of motoneuron intrinsic properties, their contribution to locomotion, and of locomotor CPGs because the genetic and molecular techniques available in Drosophila are surpassed in no other organism and because the Drosophila nervous system is small in comparison to vertebrate nervous systems. Further, whole-cell in situ patch clamp recordings from adult and larval motoneurons in relatively intact preparations are possible. Therefore, the first goal of this work was to investigate whether the firing behavior and recruitment of identified Drosophila 1b and 1s motoneurons is analogous to the recruitment of high-threshold, phasic and low-threshold, tonic motoneurons in other organisms. The second goal was to determine whether active conductances influence motoneuron recruitment in response to synaptic input. The final aim was to investigate how these factors influence CPG output to muscles. Findings from current clamp studies indicate that1b motoneurons are more easily recruited than 1s motoneurons, in agreement with the hypothesis that 1b motoneurons are analogous to low-threshold motoneurons described in other organisms. Further, orderly recruitment of Drosophila 1b motoneurons before 1s motoneurons is not a result of passive properties. Instead, the Shal channel that encodes a large portion of IA in motoneuron somatodendritic regions is a critical determinant of delay-to-spike in larval Drosophila motoneurons. These findings are behaviorally-relevant because the same recruitment order is seen in simultaneous recordings from motoneuron pairs recruited by synaptic input.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectDrosophilaen_US
dc.subjectexcitabilityen_US
dc.subjectmotor neuronen_US
dc.subjectrecruitmenten_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePhysiological Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLevine, Richard B.en_US
dc.contributor.chairLevine, Richard B.en_US
dc.contributor.committeememberDuch, Carstenen_US
dc.contributor.committeememberFregosi, Ralphen_US
dc.contributor.committeememberFuglevand, Andrewen_US
dc.contributor.committeememberRankin, Lucindaen_US
dc.identifier.proquest10995en_US
dc.identifier.oclc659754927en_US
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