Brain dopamine is critical for normal motor control, as evidenced by its importance in Parkinson Disease and related disorders. Current hypotheses are that dopamine influences motor control by 'invigorating' movements and regulating motor learning. Most evidence for these aspects of dopamine function comes from simple tasks (e.g., lever pressing). Therefore, the influence of dopamine on motor skills requiring multi-joint coordination is unknown. To determine the effects of precisely-timed dopamine manipulations on the performance of a complex, finely coordinated dexterous skill, we optogenetically stimulated or inhibited midbrain dopamine neurons as rats performed a skilled reaching task. We found that reach kinematics and coordination between gross and fine movements progressively changed with repeated manipulations. However, once established, rats transitioned abruptly between aberrant and baseline reach kinematics in a dopamine-dependent manner. These results suggest that precisely-timed dopamine signals have immediate and long-term influences on motor skill performance, distinct from simply 'invigorating' movement.

Health care workers at an academic medical center in the Midwest were surveyed to identify common practices regarding heat use during peripheral intravenous (PIV) catheter insertion. Of the 907 who responded, the majority used heat to facilitate PIV insertion at least sometimes, when veins were not easily seen or not palpable, applying a commercial dry hot pack for 2 to 5 minutes before selecting an insertion site. Heat use correlated with practice role and population, frequency of PIV insertion, and perceived PIV skill. Findings will guide development of a research protocol to compare the effects of dry heat, moist heat, and no heat on PIV insertion success.

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