Showing 1 - 10 of 11 Items
Effects of octopamine and tyramine on the cardiac system of the lobster, Homarus americanus
Date: 2019-05-01
Creator: Casey Breslow
Access: Open access
- Modulation in neural systems is important for regulating physiology and behavior (Wright et al., 2010). Peptides, hormones, and amines are common neural modulators, acting on many neural systems across species. One group of neural networks that can be regulated are central pattern generators (CPGs), which generate rhythmic neural patterns, which drive behaviors (Marder and Bucher, 2001). Octopamine, and its precursor tyramine, are two amines that have been found to regulate (CPGs) across species (Cooke, 2002; Fussnecker et al., 2006). One role of octopamine in the decapod neurogenic heart is regulating the frequency and the duration of heart beats. However, the precise site of octopamine modulation within the cardiac system is not yet known (Kurumoto and Ebara, 1991). One possible site of action is the cardiac ganglion (CG), the CPG in decapod hearts. The transcripts for the enzymes required to synthesize octopamine from tyramine have been identified and localized in the CG (Christie et al., 2018). This would suggest that octopamine is produced in the CG, where it could have a direct action on those neurons, or it could be released peripherally. We have found individual variation in the response to octopamine and its precursor tyramine, and significant effects of frequency and contraction amplitude in the whole heart.
Stretch Feedback in the Lobster Heart: Experimental and Computational Analysis
Date: 2016-05-01
Creator: Katelyn J Suchyta
Access: Open access
Neurophysiological Effects of Temperature on the Mammalian Spinal Central Pattern Generator (CPG) Network for Locomotion Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2026-06-01
Date: 2023-01-01
Creator: Eliza M. Rhee
Access: Access restricted to the Bowdoin Community
Rhythmic behaviors: Understanding neuromodulation at the neuromuscular level
Date: 2023-01-01
Creator: Kenneth Garcia
Access: Open access
- Neuromodulation allows for the flexibility of neural circuit dynamics and the outputs they produce. Studies of the stomatogastric nervous system (STNS) have expanded our knowledge on the actions of neuromodulators, small molecules that most often activate G-protein coupled receptors and reconfigure circuit activity and composition. In these systems, modulation has been found to occur at every level, from sensory-motor coupling to neuromuscular transmission (Harris-Warrick and Marder 1991). Neuromodulators have complex effects on motor output; they can alter the firing of individual neurons while also modulating muscle properties, neuromuscular transmission, and sensory neuron response to muscle activity (Fort et al. 2004). We investigated this further by recording the motor output produced by the gastric mill rhythm of the lobster STNS under neuromodulator conditions. How is this neuromuscular system as a whole modulated to produce motor flexibility? We hypothesized that these neuromodulators act on individual receptors of component neurons of central pattern generator (CPG)-effector system themselves and at the periphery, coordinately altering muscle contraction by altering all levels of the crustacean neuromuscular system. Application of NRNFLRFamide, RPCH, oxotremorine, and proctolin to the gastric mill 4 (gm4) muscles of the Cancer crab showed that neuromodulators that have been found to have variable, yet significant effects on the activity of the neurons of the STNS directly alter the activity of the gm4 muscles as well, suggesting that coordination of peripheral actions and direct neuronal modulation regulates patterned motor output.
Ultrasonic vocalization playback as an affective assay at both neural and behavioral levels: Implications for understanding adversity-induced emotional dysfunction Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Sydney M Bonauto
Access: Access restricted to the Bowdoin Community
Dietary diversity correlates with the neuromodulatory capacity of the stomatogastric nervous system in three species of majoid crabs
Date: 2023-01-01
Creator: Elise Martin
Access: Open access
- This project sought to answer the following question: what is the relationship between the extent of neuromodulation in a nervous system, and the behavioral demands on that system? A well-characterized CPG neuronal circuit in decapod crustaceans, the stomatogastric nervous system (STNS), was used as a model circuit to answer this question. The stomatogastric ganglion (STG) in the STNS is responsible for muscular contractions in the stomach that aid in digestion. It has been shown that the neural networks in the STG are subject to neuromodulation. One feature of neuromodulation is that it enables circuit flexibility, which confers upon a system the ability to produce variable outputs in response to specific physiological demands. It was hypothesized that opportunistic feeders require more extensively modulated digestive systems compared to exclusive feeders, because opportunistic feeders require a greater variety of digestive outputs to digest their varied diets. In this study, Chionoecetes opilio and Libinia emarginata, the opportunistic feeders, showed greater neuromodulatory capacity of the STNS than Pugettia producta, the exclusive feeder. The hypothesis that neuromodulatory capacity of the STNS correlates with dietary diversity was supported. The results detailed in this study lend credence to the idea that evolutionary basis for neuromodulatory capacity of a system is related to the behavioral demands on that system.
Effects of Picrotoxin Application on the Cardiac Ganglion of the American Lobster, Homarus americanus
Date: 2023-01-01
Creator: John T Woolley
Access: Open access
- Picrotoxin (PTX) has been employed extensively as a tool within the crustacean stomatogastric nervous system (STNS) for its efficacy in blocking K+ and Cl+ currents gated by both GABA and glutamate. Through blocking some currents in the STNS, PTX allows for examination of other components without their presence. However, effects of PTX are relatively unknown within the lobster’s cardiac ganglion (CG). As an incredibly small nervous system of only nine neurons, the lobster CG presents an excellent model system for studying neural circuits. Given that the chemical synapses in the CG are mediated by glutamate, the present study aimed to investigate the action of PTX in the lobster CG with the intent of better understanding its pharmacological impacts as a potential tool for studying the system. Therefore, this study aimed to establish the effects of PTX on CG responses to the application of exogenous GABA or glutamate. When data from both modulators were pooled, PTX applied at a concentration of 10-5M had significant effects on burst duration but not duty cycle or burst frequency of the CG. PTX did suppress GABA (5x10-5M) mediated inhibition of burst duration and duty cycle. PTX did not have any significant effects on burst duration, duty cycle, or frequency compared to exogenous glutamate application. These results indicate that glutamatergic inhibitory synapses are not present in the CG and PTX partially suppresses only GABAergic responses in this system.
The impact of plastic contaminants and neuroprotectants on spinal neural circuits controlling vertebrate locomotion This record is embargoed.
- Embargo End Date: 2026-05-18
Date: 2023-01-01
Creator: Violet Louise Rizzieri
Access: Embargoed
Characterization and distribution of allatostatin type-C (AST-C) neuropeptides and receptors in crustaceans Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2016-05-01
Creator: Tess Lameyer
Access: Access restricted to the Bowdoin Community
The Role of the Nitric Oxide Negative Feedback Loop in the Stability of the Lobster Cardiac Ganglion Homarus americanus Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Marie Marjorie Bergsund
Access: Access restricted to the Bowdoin Community