Alterations in Nerve Terminal Arborization do not Correlate with Increased Synaptic Efficacy in the Lobster Neuromuscular Junction.

Neurotransmitter release is essential for chemical synaptic transmission, and the efficacy of synaptic transmission depends on how much transmitter is released from discrete sites in the axon terminal called active zones. The number and structural organization of active zones are important for governing synaptic efficacy, and may play a central role in synaptic plasticity. One method to enhance synaptic strength could be to expand the nerve terminal arborization to accommodate an increase in the number of active zones. The possibility that experimentally induced increases in synaptic efficacy correlate with increases in the amount of nerve terminal arborization is tested in this Master of Science Thesis. The lobster distal accessory flexor muscle DAFM is an excellent model for studying the relationship between synaptic efficacy and the structural organization of the presynaptic axon terminal A single excitatory and inhibitory motor neuron innervate the DAFM, and the amount of transmitter they release is regionally differentiated. Regional differences in both the number and structure of active zones contribute to the regional differences in the amount of transmitter released.