Molecular and Cellular Neuroscience Commons^™

Effects Of Picrotoxin Application On The Cardiac Ganglion Of The American Lobster, Homarus Americanus, John T. Woolley

Honors Projects

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 …

The Relationship Between Circadian Rhythms And Neurodegenerative Disease, Christopher Simpson

Honors Projects

Neurodegenerative disease is a pervasive and insidious disease affecting a large proportion of the elderly population. Leading to the degeneration of neural tissue throughout the nervous system, it is a slow and progressive disorder. Because of its nature, it is possible that it has a connection to circadian rhythms. Circadian rhythms are the endogenous approximately 24-hour rhythms of the body commonly associated with the sleep-wake cycle, but they account for much more. This review aims to ascertain the relationship between the two by covering several facets of research pursued in the past five years. Beginning with establishing a basic understanding …

The Current Hunt For Nitric Oxide's Effects On The Homarus Americanus Cardiac Ganglion, Joanna Lin

Honors Projects

The crustacean heartbeat is produced and modulated by the cardiac ganglion (CG), a central pattern generator. In the American lobster, Homarus americanus, the CG consists of 4 small premotor cells (SCs) that electrically and chemically synapse onto 5 large motor cells (LCs). Rhythmic driver potentials in the SCs generate bursting in the LCs, which elicit downstream cardiac muscle contractions that are essential for physiological functions.

Endogenous neuromodulators mediate changes in the CG to meet homeostatic demands caused by environmental stressors. Nitric oxide (NO), a gaseous neuromodulator, inhibits the lobster CG. Heart contractions release NO, which directly decreases the CG burst …

Effects Of Myosuppressin, A Peptide Neuromodulator, On Membrane Currents In The Crustacean Cardiac Ganglion, Anthony Yanez

Honors Projects

Central pattern generators are neural circuits that can independently produce rhythmic patterns of electrical activity without central or periphery inputs. They control rhythmic behaviors like breathing in humans and cardiac activity in crustaceans. Rhythmic behaviors must be flexible to respond appropriately to a changing environment; this flexibility is achieved through the action of neuromodulators. The cardiac ganglion of Homarus americanus, the American lobster, is a central pattern generator made up of four premotor neurons and five motor neurons. Membrane currents in each cell type, which can be targeted for modulation by various molecules, generate rhythmic bursts of action potentials. …

Semaphorin-Induced Plasticity In The Nervous System Of The Cricket, Gryllus Bimaculatus, Alicia G. Edwards

Honors Projects

The adult auditory system of the cricket, Gryllus bimaculatus, exhibits a rare example of neuronal plasticity. Upon deafferentation, we observe medial dendrites that normally respect the midline of the PTG in the central nervous system sprouting across the boundary and forming synaptic connections with the contralateral auditory afferents. The Horch Lab has investigated key molecular factors that might play a causal role in this paradigm. Specifically, the protein Sema1a.2 comes from a guidance molecule family and has a role in developmental neuronal plasticity in other organisms. In this study, I explored the role of Sema1a.2 in the neuronal plasticity of …

Characterization Of Expression Of Sema1a Variants In High-Plasticity Areas Of The Gryllus Bimaculatus Nervous System, Sara Spicer

Honors Projects

The well-conserved semaphorin family of guidance molecules is known to play multiple complex roles in directing the growth and orientation of dendrites and axons within the developing invertebrate central and peripheral nervous system. Additionally, the expression of select semaphorins is maintained within some highly plastic areas of the adult central nervous system, such as the mushroom bodies, where they are associated with guidance of newly-born neurons as well as with synapse formation and modification. Within the cricket species Gryllus bimaculatus, deafferentation of the prothoracic ganglia and subsequent dendritic rearrangement of the auditory interneurons is associated with fluctuations in the expression …