Limbic-Motor Networks and Action Control

Abstract

Traditionally, the circuits responsible for processing cortical information of different modalities and communicating with the striatum for the purpose of guiding behavior were believed to act in separate, parallel courses. However, recent research has proposed that cortico-basal ganglia-thalamocortical loops can process limbic and sensorimotor streams in a single, open network. These novel interpretations advance the historical understanding of the ventral striatum as a limbic-motor interface by theorizing its function in influencing motor cortex activity. Yet, even as a connection between limbic function and movement is tenable, the limbic-motor junction has remained insufficiently characterized. An understanding of this intersection hinges on resolving the key players, including extrastriatal regions, messenger systems, and information domains. We sought to further examine the role of the mesial temporal lobe in motor output by concentrating on an executive function necessary for regulating movement, namely action control. We investigated dopaminergic and oscillatory features of mesolimbic regions as correlated with inhibitory tasks. To accomplish this, we first explored associations between response inhibition and mesial temporal dopamine receptor availability in a cohort of Parkinson’s disease patients. An analysis of our data revealed correlations between dopamine in the amygdala and hippocampus and response inhibition proficiency. Next, we followed up this study by considering the components of an interference inhibition task in relation to binding potential in mesolimbic structures. Here, we observed a connection between dopamine availability in the amygdala and orbitofrontal cortex and sensory motor processing. Finally, we investigated the development of neural oscillations in mesolimbic nodes during movement and non-movement. An examination of oscillatory changes in the amygdala and hippocampus disclosed evidence of beta, gamma, and delta power modulation with movement. Together, these findings demonstrate the unique interactions that exist between mesolimbic areas and movement, illustrating a compelling influence of mesial temporal regions over motor control.