Motor control mechanisms of whisking in rat.

摘要

Rhythmic movements underlie a large number of critically important motor behaviors. How different levels of neural organization and control interact to produce these movements, then, is a central question in motor control. Using the whisker system in rat we investigate the role played by the motor cortex, a key structure in the generation of complex movements, in the control of whisking. We begin by measuring the movements of the whiskers and the mastacial pad, controlled by the intrinsic and extrinsic muscles, respectively, to clarify the interaction of these two components in the organization of whisking. We find that though both contribute to movement kinematics, the whisker alone makes a relatively larger contribution. We next investigate the relationship between local field potential (LFP) activity and exploratory whisking and find that brief increases in vMCx activity precede both whisking onset and changes in whisking patterns. Lastly, we investigate the relationship between unit activity in the rhythmic subregion of vMCx and whisking in head-fixed rats engaged in one of two behavioral tasks. We find that spike rate is most often correlated with whisking amplitude/velocity, and that this relationship is independent of behavioral context. We also find occurrences of significant coherence between whisker movements and unit activity, which vary with behavioral task. These results suggest that, though the motor pattern underlying whisking is generated subcortically, vMCx plays a role in both initiating movement and modulating kinematic properties of whisking.