1. The aim of this study was to find kinematic patterns that are invariant across the normal range of locomotion speeds. Subjects walked at different, freely chosen speeds ranging from 0 9 to 2 1 m s-', while motion and ground reaction forces on the right side of the body were recorded in three-dimensional space. 2. The time course of the anatomical angles of flexion-extension at the hip and ankle was variable not only across subjects, but even from trial to trial in the same subject. By contrast, the time course of the changes in the angles of elevation of each limb segment (pelvis, thigh, shank and foot) relative to the vertical was stereotyped across subjects. 3. To compare the waveforms across speeds, data were scaled in time relative to gait cycle duration. The pattern of ground reaction forces was highly speed dependent. Several distinct families of curves could be recognized in the flexion-extension angles at the hip and ankle. Instead, the waveforms of global length and elevation of the limb, elevation angles of all limb segments and flexion-extension at the knee were invariant with speed. 4. When gait trajectories at all speeds are plotted in the position space defined by the elevation angles of the limb segments, they describe regular loops on a plane. The statistical characteristics of these angular covariations were quantified by means of principal component analysis. The first two principal components accounted together for > 99 % of the total experimental variance, and were quantitatively comparable in all subjects. 5. This constraint of planar covariation of the elevation angles is closely reminiscent of that previously described for the control of posture. The existence of laws of intersegmental co-ordination, common to the control of posture and locomotion, presumably assures the maintenance of dynamic equilibrium during forward progression, and the anticipatory adaptation to potentially destabilizing factors by means of co-ordinated kinematic synergies of the whole body.

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Regional cerebral blood flow (rCBF) PET scans were used to study the physiological bases of lipreading, a natural skill of extracting language from mouth movements, which contributes to speech perception in everyday life. Viewing connected mouth movements that could not be lexically identified and that evoke perception of isolated speech sounds (nonlexical lipreading) was associated with bilateral activation of the auditory association cortex around Wernicke's area, of left dorsal premotor cortex, and left opercular-premotor division of the left inferior frontal gyrus (Broca's area). The supplementary motor area was active as well. These areas have all been implicated in phonological processing, speech and mouth motor planning, and execution. In addition, nonlexical lipreading also differentially activated visual motion areas. Lexical access through lipreading was associated with a similar pattern of activation and with additional foci in ventral- and dorsolateral prefrontal cortex bilaterally and in left inferior parietal cortex. Linear regression analysis of cerebral blood flow and proficiency for lexical lipreading further clarified the role of these areas in gaining access to language through lipreading. The results suggest cortical activation circuits for lipreading from action representations that may differentiate lexical access from nonlexical processes.

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Background: Post-stroke recovery benefits from structured, intense, challenging, and repetitive therapy. Exergames have emerged as promising to achieve sustained therapy practice and patient motivation. This study assessed the usability and effects of exergames on balance and gait. Subjects and Methods: Sixteen elderly participants were provided with the study intervention based on five newly developed exergames. The participants were required to attend 36 training sessions; lasting for 20 minutes each. Adherence, attrition and acceptance were assessed together with (1) Berg Balance Scale, (2) 7-m Timed Up and Go, (3) Short Physical Performance Battery, (4) force platform stance tests, and (5) gait analysis. Results: Thirteen participants completed the study (18.8 percent attrition), without missing a single training session (100 percent adherence). Participants showed high acceptance of the intervention. Only minor adaptations in the program were needed based on the users' feedback. No changes in center of pressure area during quiet stance on both stable and unstable surfaces and no changes of walking parameters were detected. Scores for the Berg Balance Scale (P = 0.007; r = 0.51), the 7-m Timed Up and Go (P = 0.002; r = 0.56), and the Short Physical Performance Battery (P = 0.013; r = 0.48) increased significantly with moderate to large effect sizes. Conclusion: Participants evaluated the usability of the virtual reality training intervention positively. Results indicate that the intervention improves gait-and balance-related physical performance measures in untrained elderly. The present results warrant a clinical explorative study investigating the usability and effectiveness of the exergame-based program in stroke patients.