A Virginia Tech-led study reports that baseline firing in cerebellar Purkinje cells does not reliably predict activity in deep cerebellar nuclei neurons in several mouse models used to study movement disorders, challenging a common assumption in cerebellar research.
A study from Virginia Tech’s Fralin Biomedical Research Institute at VTC is prompting researchers to reconsider a widely used shortcut in cerebellar research: using Purkinje-cell signals as a stand-in for what is happening in the cerebellum’s output neurons.
Published in The Journal of Physiology, the work found that activity in Purkinje cells did not reliably predict activity in deep cerebellar nuclei neurons, despite the direct anatomical link in which Purkinje cells inhibit nuclei cells.
"We see that there's not a clear linear relationship between activity in the Purkinje cells and in the deep nuclei cells. So there's very limited predictive power in monitoring one to understand what's going on in the other," said Meike van der Heijden, an assistant professor at the Fralin Biomedical Research Institute at VTC.
The study’s first author, Alyssa Lyon—a doctoral candidate in Virginia Tech’s Translational Biology, Medicine, and Health Graduate Program—said the findings matter because both Purkinje and deep-nuclei activity can be disrupted in disease states.
"Purkinje and cerebellar deep nuclei cell activity is disrupted in a disease state, and a better understanding of the relationship between these neuron types will ultimately help optimize treatments for diseases such as dystonia, ataxia, and tremor," Lyon said.
One reason Purkinje cells have been studied more extensively is practical: they lie in the cerebellar cortex, closer to the brain surface, making them easier to measure than deep nuclei neurons, which are located farther below.
To test whether Purkinje-cell activity can serve as a reliable proxy, the team analyzed electrophysiology recordings from pre-clinical (mouse) models of cerebellar disease and found no significant correlation between the two cell populations.
"We suggest that if you want to know how the cerebellum is behaving in a disease state, you have to look at the deep nuclei neurons, not just the Purkinje cells," van der Heijden said.
Van der Heijden also urged caution in assuming that treatments aimed at changing Purkinje-cell activity will predictably translate into changes in deep nuclei activity.
"This is a cautionary tale for understanding cerebellar activity in disease, but also for treating these challenging diseases," she said. "We need to be very careful in making assumptions, and to actually do experiments to test our hypotheses."
Tags: ["Research","Health","Neuroscience","Brain Disorders"]
