The ventral fiber pathway for pantomime of object use.

The current concept of a dual loop system of brain organization predicts a domain-general dual-pathway architecture involving dorsal and ventral fiber connections. We investigated if a similar dichotomy of brain network organization applies for pantomime (P) and imitation of meaningless gestures (I). Impairments of these tasks occur after left hemispheric brain lesions causing apraxia. Isolated impairments and double-dissociations point towards an anatomical segregation. Frontal and parietal areas seem to contribute differently. A special role of the inferior frontal gyrus and underlying fiber pathways was suggested recently. Using a combined fMRI/DTI-approach, we compared the fiber pathway architecture of left hemispheric frontal, temporal and parietal network components of pantomime and imitation. Thereby, we separated object effects from pantomime-specific effects. P and I both engage a fronto-temporo-parietal network of cortical areas interconnected by a dorsal fiber system (superior longitudinal fascicle) for direct sensory-motor interactions. The pantomime-specific effect additionally involved the triangular part of the inferior frontal gyrus, the middle temporal gyrus, the inferior parietal cortex and the intraparietal sulcus, interconnected by ventral fibers of the extreme capsule, likely related to higher-order conceptual and semantic operations. We discuss this finding in the context of the dual loop model and recent anatomical concepts.

Interactive cueing with Walk-Mate for hemiparetic stroke rehabilitation.

BACKGROUND: Many techniques that compensate for locomotion problems in daily life using externally controlled stimulation have recently been reported. These techniques are beneficial for effortlessly supporting patients' locomotive functions, but the users of such devices must necessarily remain dependent on them. It is possible that some individuals with gait impairment may be prevented recovering locomotive function. From a rehabilitation viewpoint, it may therefore be supposed that ideally, devices that can be used in daily life to improve the locomotive functions of the body itself should be proposed. METHODS: We evaluate the effectiveness of Walk-Mate, which has been used mainly as a gait compensation device, as a gait rehabilitation training device by analyzing improvement in locomotion before, during and after rehabilitation in hemiparetic patients and comparing it with a previous gait training method. Walk-Mate generates a model walking rhythm in response to a user's locomotion in real time, and by indicating this rhythm using auditory stimuli, provides a technology that supports walking by reducing asymmetries and fluctuations in foot contact rhythm. If patients can use the system to learn a regulated walking rhythm, then it may also be expected to fulfil the functions of a gait rehabilitation training device for daily life. RESULTS: With regard to asymmetry, significantly improvements were seen for compensatory movement during training using Walk-Mate, but improvements were not retained as rehabilitative results. Regarding fluctuations in the foot contact period, significant improvement was observed for compensatory movement during training and these significant improvements were retained as rehabilitative results. In addition, it became clear that such improvement could not be adequately obtained by the previously proposed training technique utilizing constant rhythmic auditory stimulation. CONCLUSIONS: Walk-Mate effectively compensated for locomotion problems of hemiparetic patients by improving gait rhythm both during and after training, suggesting that locomotive function can be effectively recovered in some patients. The interactive mechanism of Walk-Mate may be capable of simultaneously achieving the aims of gait compensation and gait rehabilitation training methods previously developed under individual frameworks. Walk-Mate is a promising technology for assisting the reintegration of disabled persons into society.