Skill learning encoded via brain’s parallel processing in cortex and striatum
Changes in two brain areas — the cortex and striatum — underlie the transition from novel actions to refined motor skills. How discrete neuronal connections between the cortex and striatum function to encode skill learning remains unclear. Direct measurement of nerve fiber activity in vivo throughout the learning and performance of a motor skill is needed to assess how corticostriatal projections participate in skill learning.
IRP researchers led by David Lovinger, Ph.D., used a fiber photometry technique developed in intramural NIH laboratories to measure calcium signals within neurons, enabling the team to measure presynaptic activity in defined corticostriatal nerve fibers for the first time in vivo throughout the learning and refinement of a motor skill. The researchers found that associative and sensorimotor neuronal connections between the cortex and striatum are both active early in action learning, but fewer of these nerve pathways remain active as actions are refined. Furthermore, disengagement of associative, but not sensorimotor, pathways predicts individual differences in subsequent skill learning.
This information not only increases understanding of how key cortical and basal ganglia neurons interact to refine new movements into motor skills, but it may also be useful in designing external stimulation of the brain to restore movement or control unwanted movements. The study also paves the way for future research using in vivo fiber photometry to measure neuronal activity and brain changes related to a variety of behaviors.
Kupferschmidt DA, Juczewski K, Cui G, Johnson KA, Lovinger DM. (2017). Parallel, but Dissociable, Processing in Discrete Corticostriatal Inputs Encodes Skill Learning. Neuron. 96(2):476-489.