In the past two years, researchers in Kaun’s lab have used the SoRa for projects involving genetic and epigenetic regulation of how alcohol impacts memory circuits. They have also used the microscope for improving ways of visualizing dopamine and neuropeptide receptors in specific cells in memory circuits. These proteins can have complex expression patterns in memory circuits, Kaun said, so it’s critical to identify how these receptors are localized and change with the animal's experiences in each type of neuron.

Data obtained using SoRa was a key part of a collaborative project between Kaun, Professor of Brain Science Kate O’Connor-Giles, and Associate Professor of Molecular Biology, Cell Biology and Biochemistry Erica Larschan, which studied how the abuse of multiple substances influences gene regulation in memory circuits, and is being funded by the National Institute on Drug Abuse.

Analyzing synapses to understand how form influences function

Researchers in the lab of Professor of Brain Science Kate O’Connor-Giles study communication — not between humans, or flies, for that matter, but between neurons. 

“Neurons communicate with each other and target cells such as muscle at chemical synapses, where neurons release and respond to neurotransmitters,” O’Connor-Giles said. “So we're very interested in how synapses form and are organized for specific communication properties.”

Researchers in O’Connor-Giles’ lab have used the SoRa to understand how synapse architecture relates to synaptic function, as well as how synapse structure changes during plasticity.   

Audrey Medeiros, who conducted research in O'Connor-Giles' lab as a Ph.D. student and a postdoctoral researcher, used the SoRa, as well as a companion microscopy approach called STORM, to isolate, measure and analyze the differences in key aspects of synapse organization between neurons. Synapses are tiny — about 2,000 times smaller than a poppy seed — and the part that interests Medeiros is less than 50 nanometers in diameter.

“The SoRa is more user-friendly than some other approaches, and the super high resolution allows us to differentiate between objects on an extremely small scale,” said Medeiros, who recently joined the Scientific Innovation and Strategic Investments team at the Massachusetts Life Science Center. “We have images where the synapse components we’re interested in look, for example, like blobs on a traditional microscope — on the SoRa we can see we’re actually looking at one molecule with a donut shape surrounding a core cluster of a second molecule.” 

In a study published in eLife, Medeiros led a team of researchers in the O’Connor-Giles lab that used the SoRa and other tools to illuminate how differences in synapse organization between neurons with similar roles can shape functional synaptic diversity, which allows the nervous system to perform complex functions.

Building on seed funding from the institute’s Zimmerman Innovation Awards program, the team is now partnering with researchers in Kaun’s lab to bring some of the approaches they use to study synapse structure to an investigation of reward-relevant neural circuits.

“We've done a really good job using the SoRa to answer some of the questions we had about synapse reorganization during plasticity,” Medeiros said. “For example, we discovered that certain protein molecules are rapidly increased at synapses to support changes in function. Now we're working with Karla's lab to try to see how synapses are reorganized during the formation of reward memories.”

Untangling the wiring of the nervous system

In the lab of Alexander Jaworski, an associate professor of brain science, researchers are studying the cellular and molecular mechanisms of nervous system wiring. For one project, they used the SoRa to characterize the functions of a novel molecule that helps developing neurons follow the right path to establish proper synaptic connections, Jaworski explained.

“Understanding this process could reveal strategies for helping re-establish connections lost due to injury or neurodegenerative disease,” he said.

The research team focuses on the brains of mouse embryos to understand how neurons wire up with one another and form functional circuits. They have been studying one particular signaling molecule that turns out to be particularly important for wiring sensory neurons, and the researchers were able to use the SoRa to see what happened to developing sensory neurons when they inactivated the gene encoding this protein.

“Each segment of the spinal cord has some of the sensory neurons involved in controlling the body's sensation of touch, pain and other stimuli,” Jaworski said. “These neurons appear in repeated patterns. We wanted to be able to acquire images of an entire segment of the spinal cord to see these patterns, and for that, the SoRa was really instrumental.”

The SoRa microscope in confocal mode allowed the team to peer through thicker sample sections than they could study with a regular microscope, and to see a 3D view of entire segments of the spinal cord. 

For this study, which is currently published as a pre-print, Jaworski’s team identified a “guidance molecule” involved in the wiring of mouse peripheral sensory neurons, as well as the receptors that mediate the responses to this molecule. 

Because the molecule is also expressed in other parts of the developing nervous system, the team is now exploring its functions beyond its role in sensory neurons.

“We still have a lot of questions about the precise molecular mechanisms involved in signaling,” Jaworski said. “There's also the potential that this guidance molecule might actually control the wiring of many different types of neurons during brain development. That's something we're trying to drill down on.”