Thursday, May 30, 2013

Image post 5: eye nerves shed light on memory disorders

While most posts from The Mix feature a science story, we have also begun sharing images coming out of UAB research. Below is a brief description of what we are looking at and how related work may contribute to a better understanding of Alzheimer's disease.

Pictured here is a retinal ganglion (center), a kind of nerve cell near the eye’s retina that helps to process light into the images we perceive. It had been injected with a fluorescent dye, which made it glow green along with the cells connected to it electrically. In each of our eyes, 125 million photoreceptors capture light. They then trigger nerve messages in 1.5 million retinal ganglion cells, long extensions of which bundle together to form the optic nerve.

Captured by Christianne Strang, Ph.D., research instructor in the Department of Vision Sciences within the UAB School of Optometry, this image represents signaling mechanisms between the retina and surrounding nerve cells. Strang's lab seeks to understand how photoreceptors connect to surrounding nerve pathways, as well as the degree to which they signal using the neurotransmitter acetylcholine.

Within nerve pathways, each nerve cell sends an electric pulse down an extension of itself called an axon until it reaches a synapse, a gap between itself and the next cell in line. When it reaches an axon’s end, the pulse triggers the release of chemicals called neurotransmitters that float across the gap. Upon reaching the other side, they either cause the downstream nerve cell to “fire” and pass on the message, or stop the message. Certain neurological diseases, including Alzheimer’s, have been linked to a decrease in acetylcholine signals in nerve pathways related to vision and memory.

As for rest of the color scheme, the pictured eye tissue has also been treated with dyes that interact with choline acetyltransferase (blue), which helps to produce acetylcholine, and synaptophysin (red), which reveals the location of synapses. The work was done in the lab of Kent Keyser, Ph.D., professor in the School of Optometry.

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