Performance errors drive motor learning for many tasks. Some researchers have suggested that reducing performance errors with haptic guidance can benefit learning by demonstrating correct movements, while others have suggested that artificially increasing errors will force faster and more complete learning. This study compared the effect of these two techniques--haptic guidance and error amplification--as healthy subjects learned to play a computerized pinball-like game. The game required learning to press a button using wrist movement at the correct time to make a flipper hit a falling ball to a randomly positioned target. Errors were decreased or increased using a robotic device that retarded or accelerated wrist movement, based on sensed movement initiation timing errors. After training with either error amplification or haptic guidance, subjects significantly reduced their timing errors and generalized learning to untrained targets. However, for a subset of more skilled subjects, training with amplified errors produced significantly greater learning than training with the reduced errors associated with haptic guidance, while for a subset of less skilled subjects, training with haptic guidance seemed to benefit learning more. These results suggest that both techniques help enhanced performance of a timing task, but learning is optimized if training subjects with the appropriate technique based on their baseline skill level.

Background The liver is one of the most frequently injured abdominal organs. Hepatic hemorrhage is a complex and challenging complication following hepatic trauma. Significant shifts in the treatment of hepatic hemorrhage, including the increasing use of angioembolization, are believed to have improved patient outcomes. We aimed to describe the efficacy of angioembolization in the setting of acute hepatic arterial hemorrhage, as well as the complications associated with this treatment modality. Methods A systematic review of published literature (MEDLINE, SCOPUS, and Cochrane Library) describing hepatic angioembolization in the setting of trauma was performed. Articles that fulfilled the predetermined inclusion and exclusion criteria were included. We analyzed the efficacy rate of angioembolization in the setting of traumatic hepatic hemorrhage as well as the complications associated with hepatic angioembolization. Results Four hundred and fifty nine articles were identified in the literature search. Of these, 10 retrospective studies and 1 prospective study met inclusion and exclusion criteria. Efficacy rate of angioembolization was 93%. The most frequently reported complications following hepatic angioembolization included hepatic necrosis (15%), abscess formation (7.5%), and bile leaks. Conclusion Although the outcomes of hepatic angioembolization were generally favorable with a high success rate, the treatment modality is not without associated morbidity. The most frequently associated major complication was hepatic necrosis. Rates of complications were affected by study heterogeneity and should be better defined in future studies.