Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons
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Case Western Reserve University School of Graduate Studies / OhioLINK
2014
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ndltd-OhioLink-oai-etd.ohiolink.edu-case13966176342021-08-03T06:23:19Z Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons McManus, Jeffrey M. Biology Neurobiology multifunctionality Aplysia feeding neuromodulation regional muscle activation motor neurons Animals must use the same peripheral structures to generate different behaviors. What are the mechanisms by which a nervous system uses the same muscles in the generation of distinctly different tasks? In this dissertation, this question is addressed through studies of the I3 muscle of the marine mollusk Aplysia californica’s multifunctional feeding system. The I3 muscle is known as the primary retractor of the animal’s food grasper, contracting to push the grasper toward the esophagus. The motor pool for I3 contains identified motor neurons with different, overlapping regions of innervation, so that it is possible to activate the entire muscle or a single region of the muscle. The studies in this dissertation focus on three mechanisms for the generation of multifunctionality: differential deployment of motor neurons, regional muscle activation, and neuromodulation.To understand the roles of muscles and the identified neurons that activate them in generating multifunctionality, it is important to place their activity in a behavioral context. Thus, a novel experimental preparation for eliciting behavioral movements in vitro while recording from single neurons was developed. Following the description of this protocol are studies of two identified motor neurons for I3: B38 and B39. Both activate I3’s anterior, and thus cause regionally specific muscle activation. Both neurons are shown to be recruited at specific times in specific behaviors. B38 is active during the protraction phase of swallowing behaviors and mediates jaw closure to hold food, providing an additional function for the retractor muscle I3. I3 is thus shown to be a multifunctional muscle. B39 is active during the early retraction phase of rejection behaviors, and could help initiate retraction without closing the grasper on the object being rejected. Using knowledge of the biomechanical contexts, explanations are provided for the reasons it is critical that B38 and B39 specifically activate a region and not the whole muscle, and the reasons it is critical that they are recruited in specific behaviors. Additionally, for B38, quantifications of in vivo activity are used to show that neuromodulation is necessary for in vivo activity to cause significant muscle contractions. This neuromodulation aids in the generation of multifunctionality by preparing the system for switches from one behavior to another.Differential deployment of the elements of a motor pool in different behaviors, regional heterogeneity of muscle activation and function, and neuromodulation are all important research topics that have been studied in many different systems. By examining all three of these mechanisms together and tying them to the activity of individual, identified neurons in a behavioral context, this dissertation provides novel findings of how nervous systems generate multifunctionality and helps lay the groundwork for several lines of future research. 2014-06-11 English text Case Western Reserve University School of Graduate Studies / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=case1396617634 http://rave.ohiolink.edu/etdc/view?acc_num=case1396617634 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Biology Neurobiology multifunctionality Aplysia feeding neuromodulation regional muscle activation motor neurons |
| spellingShingle |
Biology Neurobiology multifunctionality Aplysia feeding neuromodulation regional muscle activation motor neurons McManus, Jeffrey M. Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons |
| author |
McManus, Jeffrey M. |
| author_facet |
McManus, Jeffrey M. |
| author_sort |
McManus, Jeffrey M. |
| title |
Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons |
| title_short |
Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons |
| title_full |
Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons |
| title_fullStr |
Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons |
| title_full_unstemmed |
Multifunctionality of the I3 Muscle of Aplysia via Regional Activation by Identified Neurons |
| title_sort |
multifunctionality of the i3 muscle of aplysia via regional activation by identified neurons |
| publisher |
Case Western Reserve University School of Graduate Studies / OhioLINK |
| publishDate |
2014 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=case1396617634 |
| work_keys_str_mv |
AT mcmanusjeffreym multifunctionalityofthei3muscleofaplysiaviaregionalactivationbyidentifiedneurons |
| _version_ |
1719435800892932096 |