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| Jennifer Morgan | |
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Assistant Professor Ph.D. Office PAT 522 Morgan Lab home page |
| The process by which neurons communicate with each other is called synaptic transmission, and it underlies all human social, cognitive, motor and sexual behaviors. Communication between neurons occurs at specialized contact sites, chemical synapses, where one neuron releases neurotransmitters onto the other neuron. In this way the two neurons “talk to” one another. Thus, the structural and functional integrity of synapses must be maintained in order for the neurons to communicate over the long term. Yet synapses must be dynamic and flexible in order to adapt to changes in the environment. In my lab, we are exploring the molecular mechanisms underlying both synaptic maintenance and synaptic plasticity. The actin cytoskeleton may be a key player at synapses. In non-neuronal cells, the actin cytoskeleton can be stable, providing structural support for a cell, or it can be dynamic, generating the forces that drive many cellular functions. However, in neurons, particularly at the pre-synapse, the roles of actin are still unclear. Thus, the current goals of our research are: 1) to elucidate the roles of presynaptic actin in synapse maintenance (vesicle trafficking; cell adhesion) and 2) to determine whether actin participates in synapse regeneration following axonal injury. My experiments take advantage of the giant synapses found within axons of the lamprey spinal cord. Each synapse has a prominent ring of actin surrounding sites of neurotransmitter release, making this the ideal preparation in which to study presynaptic actin. We use electrophysiology, imaging, biochemistry, and molecular biology techniques toward our goals. Recently, we have also developed behavioral and anatomical assays with which to explore the role of actin during spinal cord regeneration. Since synaptic actin has been implicated in a wide variety of neurological and neuromuscular disorders, our studies have wide-ranging implications for human health. 
Actin is present at lamprey giant synapses. A) Confocal image showing a
single lamprey axon injected with a fluorescent marker for actin. Each
actin ring represents a giant synapse. B) Higher magnification image
showing that the actin ring (green) surrounds vesicle clusters (red) at
sites of neurotransmitter release. Bar in each panel equals 5 µm.
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