With the help of the rabies virus, McGowan Institute for Regenerative Medicine
affiliated faculty member Peter Strick, PhD, professor within the departments of Neurobiology and Psychiatry at the University of Pittsburgh and the co-director of the Center for the Neural Basis of Cognition, and his team are mapping the complex, intermingled neurologic circuitry of the brain. In her PittMed article, author Melinda Wenner Moyer describes how rabies helped Dr. Strick recently discover a division in the human motor cortex that could explain why we exhibit more finely tuned movements than other animals. Rabies also helped him uncover a surprising connection between two brain regions that solves a mystery about Parkinson’s disease.
Explains Dr. Strick, “We start by asking what the [brain’s] road map is. And viruses are a wonderful way of working out that road map.”
The results of Dr. Strick’s research efforts using rabies have been featured in the Proceedings of the National Academy of Sciences of the USA. His 2009 work helps scientists better understand human dexterity. In an animal model, he gave the virus enough time to infect not two but three steps back, traveling along two motor neurons on its journey. Earlier work by other researchers revealed that humans and rhesus monkeys—but not cats and rats—have some brain-to-muscle connections via just one neuron.
Dr. Strick and his colleagues have also used rabies to discover new connections between brain regions. In their 2010 paper, they showed that the cerebellum, a brain region involved in motor control and motor learning, communicates with the basal ganglia, a group of forebrain regions involved in movement and habit formation. Malfunctions in the basal ganglia are also thought to be responsible for producing tremors in patients with Parkinson’s disease. Earlier research by other scientists had shown that Parkinson’s patients have abnormal activity in the cerebellum, but no one knew why. When Strick’s colleagues injected rabies into the cerebellums of the animal model, he saw that they connected to the basal ganglia by way of two neurons. “It’s not a direct connection; that’s why it wasn’t seen with conventional tracers,” he says. Dr. Strick believes that the basal ganglia are sending abnormal signals to the cerebellum, which in turn is either trying to correct for them or is relaying them. If the latter is true, the cerebellum may be more directly responsible for Parkinson’s tremors, a finding that could have important implications for treatment.
Illustration: McGowan Institute for Regenerative Medicine.
PittMed (Winter 2010)
Bio: Dr. Peter Strick
Abstract (Proceedings of the National Academy of Sciences of the U S A. 2009 Jan 20;106(3):918-23.)
Abstract (Proceedings of the National Academy of Sciences of the U S A. 2010 May 4;107(18):8452-6.)