Abstract: OBJECTIVE. The dart-throwing motion (DTM) is a multiplane wrist motion that is needed for many daily occupations. Mobilization along the DTM plane may be essential for rehabilitation after wrist injury, but DTM angles are reported for the dominant hand alone, so their relevance to injury in the nondominant hand cannot be surmised. The aim of this study was to quantify the DTM plane angles for both hands during different activities of daily living (ADLs).
METHOD. Forty-three healthy participants wore a twin-axis electrogoniometer during ADLs.
RESULTS. No significant differences were found between the DTM plane angles of the dominant (20°�45°) and nondominant (15°�40°) hands. These angles varied by task and across participants.
CONCLUSION. The DTM plane is a functional motion used by both hands during ADLs. Because the DTM plane angle differs among hands, tasks, and individual clients, wrist rehabilitation involving the DTM plane should not be limited to a singular DTM plane angle.OBJECTIVE. The dart-throwing motion (DTM) is a multiplane wrist motion that is needed for many daily occupations. Mobilization along the DTM plane may be essential for rehabilitation after wrist injury, but DTM angles are reported for the dominant hand alone, so their relevance to injury in the nondominant hand cannot be surmised. The aim of this study was to quantify the DTM plane angles for both hands during different activities of daily living (ADLs).
METHOD. Forty-three healthy participants wore a twin-axis electrogoniometer during ADLs.
RESULTS. No significant differences were found between the DTM plane angles of the dominant (20°�45°) and nondominant (15°�40°) hands. These angles varied by task and across participants.
CONCLUSION. The DTM plane is a functional motion used by both hands during ADLs. Because the DTM plane angle differs among hands, tasks, and individual clients, wrist rehabilitation involving the DTM plane should not be limited to a singular DTM plane angle.

Abstract: Numerous studies have examined control of force magnitude, but relatively little research has considered force direction control. In this study, subjects applied isometric forces to a handle and we compared within-trial variability when producing force in different directions. The standard deviation (SD) of the force parallel to the prescribed direction of force production increased linearly with the targeted force level, as did the SD of the force perpendicular to the instructed direction. In contrast, the SD of the angle of force production decreased with increased force level. In the four (of eight) instructed force directions where the endpoint force was generated due to a joint torque in only one joint (either the shoulder or elbow) the principal component axes in force space were well aligned with the prescribed direction of force production. In the other directions, the variance was approximately equal along the two force axes. The variance explained by the first principal component was significantly larger in torque space compared to the force space, and mostly corresponded to positive correlation between the joint torques. Such coordinated changes suggest that the torque variability was mainly due to the variability of the common drive to the muscles serving two joints, although this statement needs to be supported by direct studies of muscle activation in the future.

Abstract: Mu suppression is the attenuation of EEG power in the alpha frequency range (8-12 Hz), recorded over the sensorimotor cortex during execution and observation of motor actions. Based on this dual characteristic it is thought to signalize activation of a human analogue of the mirror neuron system (MNS) found in macaque monkeys, though much uncertainty remains concerning its specificity and full significance. To further explore the hypothesized relationship between mu suppression and MNS activation, we investigated how it is affected by damage to cortical regions, including areas where the MNS is thought to reside. EEG was recorded in 33 first-event stroke patients during observation of video-clips showing reaching and grasping hand movements. We examined the modulation of EEG oscillations at central and occipital sites, and analyzed separately the lower (8-10 Hz) and higher (10-12 Hz) segments of the alpha/mu range. Suppression was determined relative to observation of a non-biological movement. Normalized lesion data were used to investigate how damage to regions of the fronto-parietal cortex affects the pattern of suppression. The magnitude of mu suppression during action observation was significantly reduced in the affected hemisphere compared to the unaffected hemisphere. Differences between the hemispheres were significant at central (sensorimotor) sites but not at occipital (visual) sites. Total hemispheric volume loss did not correlate with mu suppression. Suppression in the lower mu range in the unaffected hemisphere (C3) correlated with lesion extent within the right inferior parietal cortex. Our lesion study supports the role of mu suppression as a marker of MNS activation, as suggested by findings gathered in previous studies in normal subjects.