A new paper out in Nature Communications explores a form of motor learning known as “motor adaptation,” or the capacity to maintain motor performance in an ever fluctuating environment. Research like this has implications for neurological disorders such as ataxia and motor coordination deficits. Max Planck Florida postdoc Dr. Audrey Bonnan is the lead author on this new paper.
Audrey’s research focuses on the neuronal basis of motor learning in the cerebellum, a brain structure primarily studied for its role in motor functions. More specifically, she studies how neuronal signaling and plasticity in cerebellar microcircuits contribute to changes in motor performance during learning, using vestibulo-ocular reflex adaptation as a model system. For her latest paper, Audrey worked in the MPFI Christie lab, but collaborated with the neighboring Bolton lab to take advantage of new techniques for isolating and manipulating signals at the cellular level.
“We used a combination of techniques to study how different instructive signals impose learned changes at the neuronal and behavioral level. We found that manipulating calcium activity in Purkinje cell dendrites (Purkinje cells are the sole output of the cerebellum) can result in different sign of plasticity at the cellular level (i.e. a potentiation or a depression of synaptic strength) and in different direction of learning at the behavioral level (i.e. either a strengthening or weakening of the motor response to the same stimulation), depending on the level of calcium,” she explained.
As an electrophysiologist by training, one of the challenges for Audrey was learning how to do behavioral experiments. But Audrey was up for the challenge, and was even awarded an International Training Support grant from the Max Planck society to visit labs in Germany and the Netherlands and get immersive experience in new skills for her project such as best practices and techniques to track eye movements in mice. “I use optogenetics to manipulate cellular activity in vitro and in vivo and the first time I successfully targeted the appropriate brain region and was able to “artificially” evoke an eye movement was pretty crazy! I was really excited, until then I was always recording neuronal activity but now I was able to alter behavior in order to study memory formation in the cerebral circuit,” she shared.
The cerebellum is not only important for motor coordination and balance. There is now accumulating evidence that it also plays a role in more cognitive functions and that cerebellar dysfunctions could contribute to the pathophysiology of neurodevelopmental disorders such as Autism Spectrum Disorder and Schizophrenia. As Audrey makes plans to start a lab of her own, this will continue to be a line of questioning she will pursue. “I plan to continue to dissect the neuronal basis of motor memory formation during physiological learning, looking at the role of different cell types such as molecular layer interneurons. My long-term goal is to use the same learning paradigm to study how cerebellar circuits might be altered in neurodevelopmental disorders resulting in aberrant motor learning,” she said.
Audrey brings a natural talent and curiosity to the lab, which has been a big part of her success. But she also points to the environment at Max Planck Florida for making this latest project possible. “MPFI provides an excellent scientific environment, allowing to take risks such as using cutting edge, new techniques to answer our scientific questions. It also fosters collaborations between teams that allow the projects to move forward.”
Dr. Bonnan’s new paper “Autonomous Purkinje cell activation instructs bidirectional motor learning through evoked dendritic calcium signaling” is in the April 2021 edition of Nature Communications and can be found here.