Sniffing out Parkinson's

September 23, 2011 By Christine Buckley
Brain signaling, Parkinson's disease, and the sense of smell are all related in unexpected ways in a study by associate professor Joanne Conover, right, and graduate student Jessica Lennington. Credit: Daniel Buttrey/UConn Photo

A team of neuroscientists in UConn's College of Liberal Arts and Sciences has mapped the brain’s nerve connections that help control the sense of smell, which could add another brain region to the list of those affected by Parkinson’s Disease.

“Scientists are very interested in the connectivity of the brain,” says Joanne Conover, associate professor in the Department of Physiology and Neurobiology. “The better we can define the neuron populations in the brain, the better we can grasp how they are targeted for degeneration in diseases like Parkinson’s.”

Conover’s graduate student Jessica Lennington led a study focused on one of the few parts of the brain that continues to produce new neurons from stem cells after embryonic development and throughout adulthood. The region, called the subventricular zone, or SVZ, is in the center of the brain and plays a role in controlling animals’ sense of smell.

Clinical studies show that patients with Parkinson’s disease often gradually lose their sense of smell as the disease progresses. Neurobiologists think that this loss has to do with changes in signaling by – one of the most important signaling molecules in the brain – within and around the SVZ.

“People are looking for factors that regulate the SVZ, and dopamine is one of these factors,” Conover says. “We wanted to know: where is the dopamine coming from?”

Scientists previously thought a nearby brain region that controls motor function was sending dopamine to the SVZ. Lennington tested this idea using a fluorescent dye to trace the path of the dopamine neurons from the SVZ to their site of origin in the midbrain, which she visualized under a confocal microscope.

A segment of the mouse brain glows with fluorescent markers that show dopamine neurons. The green cells provide dopamine to the subventricular zone, a region that produces new neurons throughout adulthood to regulate the sense of smell. Credit: Jessica Lennington

What she found was completely unexpected.

“In all cases, there was a little region that was lighting up in a different part of the midbrain, not the region that others had previously assumed to be the origin,” she says.

The midbrain area that glowed with dopamine molecules is involved in basic processes like motivation, aversion, and rewards, which Conover and Lennington point out are intuitively associated with smell.

And being able to smell things, says Lennington, has been associated throughout evolution not just with deciding whether something’s good to eat, but with a host of survival decisions.

“It’s also involved in mating, parenting, and sensing seasonal changes,” she says.

This discovery, says Conover, suggests that Parkinson’s disease may also affect an area of the brain not previously associated with the disease. Although this study looked at mouse brains according to National Institutes of Health standards, Conover thinks the same could be true in the human brain.

Studies like these are the necessary small steps in understanding how all the many sections of the brain communicate with one another, she says.

“This was not an easy project because our data suggested something different from what others had previously reported. We had to prove what was going on while disproving others’ work,” says Conover. “It’s exciting to have it all come together.”

Lennington, who will defend her doctoral dissertation this semester, says that future work in this area will continue identifying the differences between populations of nerve cells that use dopamine in the .

“It’s still not known why the neurons involved in Parkinson’s degenerate,” says Conover. “We can speculate, but we don’t have this all figured out.”

Also involved in the study were former student Sara Pope, and current undergraduates Anna Goodheart and Linda Drozdowicz, physiology and neurobiology majors, and Board of Trustees Distinguished Professor of Psychology John Salamone. Stephen Daniels of the Department of Physiology and Neurobiology also participated in the study. The study was published on Sept. 14 in the Journal of Neuroscience.

Explore further: Nerve cells grown from stem cells give new insight into Parkinson's

Related Stories

Nerve cells grown from stem cells give new insight into Parkinson's

June 20, 2011
Oxford University researchers have succeeded in using stem cell technology to grow nerve cells in the laboratory from initial skin samples taken from Parkinson’s patients. It’s the first large-scale effort of its ...

Falls may be early sign of Alzheimer's

July 18, 2011
Falls and balance problems may be early indicators of Alzheimer’s disease, researchers at Washington University School of Medicine in St. Louis report July 17, 2011, at the Alzheimer’s Association International ...

How the brain processes humour helps us understand emotions felt by vegetative state patients

July 7, 2011
(Medical Xpress) -- How the human brain processes jokes may help researchers determine if a person in a vegetative state can experience positive emotions – a breakthrough that could help friends, relatives and doctors ...

Recommended for you

Researchers make surprising discovery about how neurons talk to each other

August 17, 2017
Researchers at the University of Pittsburgh have uncovered the mechanism by which neurons keep up with the demands of repeatedly sending signals to other neurons. The new findings, made in fruit flies and mice, challenge ...

How we recall the past: Neuroscientists discover a brain circuit dedicated to retrieving memories

August 17, 2017
When we have a new experience, the memory of that event is stored in a neural circuit that connects several parts of the hippocampus and other brain structures. Each cluster of neurons may store different aspects of the memory, ...

Researchers show how particular fear memories can be erased

August 17, 2017
Researchers at the University of California, Riverside have devised a method to selectively erase particular fear memories by weakening the connections between the nerve cells (neurons) involved in forming these memories.

Neurons involved in learning, memory preservation less stable, more flexible than once thought

August 17, 2017
The human brain has a region of cells responsible for linking sensory cues to actions and behaviors and cataloging the link as a memory. Cells that form these links have been deemed highly stable and fixed.

Scientists identify central neural circuit for itch sensation

August 17, 2017
Itching is an unpleasant sensation associated with the desire to scratch, and the itch sensation is an important protective mechanism for animals. However, chronic itch, often seen in patients with skin and liver diseases, ...

Study uncovers specialized mouse neurons that play a unique role in pain

August 17, 2017
Researchers from the National Institutes of Health have identified a class of sensory neurons (nerve cells that electrically send and receive messages between the body and brain) that can be activated by stimuli as precise ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.