The vast majority of theses in this collection are open access and freely available. There are a small number of theses that have access restricted to the WWU campus. For off-campus access to a thesis labeled "Campus Only Access," please log in here with your WWU universal ID, or talk to your librarian about requesting the restricted thesis through interlibrary loan.
Date Permissions Signed
Date of Award
Master of Science (MS)
Serrano-Moreno, José Ramón
Retrograde signaling from downstream effectors (i.e., motor neurons) can modulate plasticity. Much research has focused on the learned association of closely timed sensory stimuli. By comparison, there is less research probing the potential influence of how or if activation at downstream neuromuscular junctions (NMJ) could modulate associative conditioning. Using channelrhodopsin activation of body wall muscle and different motor neuron subsets (cholinergic motor neurons that drive contraction and GABAergic motor neurons that drive relaxation of muscle) in the Caenorhabditis elegans (C. elegans) model system, we examined if concurrent excitation in these downstream circuits influences associative conditioning.
Conditioning consisted of pairing two distinct sensory stimuli, mechanosensory (vibration) and blue light (~480nm). Each stimulus drives a locomotor response on its own and we have shown that pairing delivery of these two stimuli alters the subsequent locomotor response to vibration. Animals that expressed channelrhodopsin in the body wall muscle (pmyo-3::ChR2), excitatory motor neurons (punc-17::ChR2) or the inhibitory motor neurons (punc-47::ChR2) received associative vibration-light conditioning. Thus, the blue light stimulus simultaneously functioned as both associating sensory stimulus and activator of channelrhodopsin, when the necessary cofactor was present, all-trans-retinol (ATR+).
Results showed wild type C. elegans typically pause for a longer duration following associative vibration-light conditioning. Following vibration-light conditioning, pmyo-3::ChR2 exhibited a complete disruption of learning. While trained ATR+ punc-17::ChR2 and punc-47::ChR2 animals showed partially disrupted conditioned locomotor behavior, as compared to controls. Together, this data suggests that co-activation of the downstream body wall muscle and motorneurons interferes with upstream associative conditioning.
Acetylcholine, Associative Conditioning, Body Wall Muscle, GABA, Learning, Neuromuscular Junction
Western Washington University
Subject – LCSH
Caenorhabditis elegans--Nervous system; Neuromuscular transmission; Motor neurons; Conditioned response; Optogenetics
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.
Pribic, Micaela R., "Neural Signaling Dynamics of Conditioning in C. elegans" (2020). WWU Graduate School Collection. 931.