My lab focuses on three main questions: 1) How do neural circuits through the basal ganglia, cerebellum and motor cortex enable skillful movement in the healthy brain? 2) How do abnormalities in these neural circuits produce the symptoms of basal ganglia-related disorders such as Parkinson's disease and dystonia? 3) How does deep brain stimulation (DBS) work to alleviate symptoms in these disorders?
For most of us reaching to grasp an object seems an almost effortless task, despite the profound difficulty of the underlying control problems. The central network that solves this problem includes regions of cortex, the basal ganglia, cerebellum, and thalamus. One goal of my research is to tease apart the relative roles of the basal ganglia and motor cortices in learning and controlling skillful arm movements. In recent results we found, contrary to expectation, that the basal ganglia circuit is not necessary for the execution of well-learned motor sequences. We plan to extend this work to test basal ganglia roles in several forms of motor learning (i.e., sequence learning and adaptation).
Pathology within the basal ganglia, such as the degeneration of dopamine cells in Parkinson's disease, leads to distinct disorders of movement. Another central theme in my research is to understand the physiologic mechanisms that lead from local pathology to specific behavioral impairments (i.e., parkinsonian akinesia, bradykinesia and rigidity). We are currently testing hypotheses concerning roles of the motor cortices in these parkinsonian signs.
High frequency electrical stimulation through electrodes implanted deep in the brain (i.e., Deep Brain Stimulation, DBS) is a highly effective therapy for several medically intractable disorders. Despite the growing popularity of DBS, we are only beginning to understand the physiologic mechanisms that mediate its therapeutic effect. An ongoing project investigates the local and network-wide mechanisms of action of DBS with the goal of improving its efficacy.
Projects in my lab typically use a combination of multi-electrode neuronal recording and pharmacologic manipulations of local neuronal activity in awake behaving animals. Most experiments are conducted in non-human primates trained to perform motor tasks.
Turner RS, Desmurget M. Basal ganglia contributions to motor control: a vigorous tutor. Curr Opin Neurobiol. 2010; 20:704-16. PMCID: PMC3025075
Pasquereau B, Turner RS. Dopamine neurons encode errors in predicting movement trigger occurrence. J Neurophysiol. 2015; 113:1110-23. PMCID:PMC432943
Zimnik AJ, Nora GJ, Desmurget M, Turner RS. Movement-related discharge in the macaque globus pallidus during high frequency stimulation of the subthalamic nucleus. J Neurosci. 2015; 35:3978-89. PMCID: PMC4348192
Pasquereau B, DeLong, MR, Turner RS. Primary motor cortex of the parkinsonian monkey: Altered encoding of active movement. Brain 2016; 139:127-43. PMCID: PMC4794619
Pasquereau B, Turner RS. A selective role for ventromedial subthalamic nucleus in inhibitory control. eLife 2017; 6: e31627. PMCID: PMC5730370
Pasquereau B, Tremblay L, Turner RS. Local field potentials reflect dopaminergic and nondopaminergic activities within the primate midbrain. Neurosci. 2018; 399:167-183. PMCID: PMC6475451