Date of Award

Spring 5-2022

Document Type

Honors Thesis

Degree Name

Bachelor of Science

Department

Biological Science

Advisor/Committee Chair

Gregory Lnenicka

Committee Member

Damian G. Zuloaga

Abstract

An activity-dependent increase in postsynaptic currents produced by a single vesicle of neurotransmitter is an important mechanism for synaptic plasticity in the central nervous system (CNS) and possibly involved in learning and memory. We have found a similar form of postsynaptic potentiation at the D. Melanogaster neuromuscular junction (NMJ) where a brief increase in impulse activity results in an increase in the amplitude of spontaneous miniature excitatory postsynaptic currents (mEPSCs), resulting in miniature excitatory postsynaptic potentials (mEPSPs). To visualize sites of postsynaptic potentiation along the synaptic terminal, we have used a Ca2+ indicator, GCaMP to observe postsynaptic Ca2+ signals. Since the postsynaptic glutamate receptors admit Ca2+, these postsynaptic Ca2+ signals should reflect the magnitude of the mEPSCs. We can observe the postsynaptic potentiation using this technique since a brief increase in impulse activity produces an increase in the amplitude of the Ca2+ signal. To confirm that the Ca2+ signals are responsible for the previously observed increases in mEPSPs, I have developed an analysis technique to match the Ca2+ signals and mEPSPs produced by the same vesicle of neurotransmitter. This approach matches the two events correctly. Our data suggests that in most cases, there is a correlation between Ca2+ signal amplitudes and mEPSP amplitudes in unstimulated preparations. This will allow us to use GCaMP imaging to study postsynaptic potentiation at these synapses. We also found no correlation in unstimulated preparations that would suggest a possible function of the muscle subsynaptic reticulum in filtering synaptic current.

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