دانلود رایگان مقاله درک اختلال حرکات انسان در بیماری پارکینسون

ABSTRACT

Interacting with other individuals in a social world requires fast and accurate perception of other individuals’ identity, actions, or intentions. Humans are very efficient in these social tasks, as they can extract social information even if the actor is represented only by a handful of point-lights on an otherwise invisible body. Theories have argued that efficient visual perception of actions is based on intact motor system functioning. The motor system provides visuo-motor action representations shaped by the observer’s own movements or motor repertoire. If the observer’s motor repertoire is impaired, this should lead to impaired visuo-motor representations and ultimately to impaired visual perception of movements. Here we tested this hypothesis in a behavioral study with patients suffering from Parkinson’s disease (PD). PD patients are typically impaired in movement execution. We tested these patients and a matched control group in a visual discrimination task on human movement perception. The results showed that PD patients were significantly impaired in the perception of human movements. This impairment was most prominent for transitive (object-related) movements. The results indicate that impaired movement execution critically influences movement perception. The results support the hypothesis that the motor system plays a causal role for the visual perception of human movements

4. Discussion

We assessed the perception of human point-light actions in patients with Parkinson’s disease (PD) and a healthy control group. We tested the ability to recognize the actions in three tasks in which subjects had to discriminate a natural human movement from different types of unnatural movements. PD patients showed lower recognition rates in all conditions compared to control subjects, albeit only the difference in the natural/incoherent condition was statistically significant. In post-hoc tests, we found that this difference was due to significant lower recognition rates for natural movements, while the recognition of incoherent movements was similar to the control group. Finally, we found that the difference between PD and control groups was significantly stronger for transitive compared to intransitive movements. The results confirmour hypothesis that PD patients are impaired in the perception of human movements. It is unlikely that the impairment is induced by the medication the patients are regularly taking, because medication was withdrawn for >12 h. 12 h withdrawal is a standard procedure regularly applied in studies and sufficient to reduce the concentration of the medication to a negligible concentration [35–37,45]. The impairment is unlikely to arise from general impairments of visual perception or cognitive abilities, or by a bias to towards reporting unnatural movements,because both effects should have affected perception of natural and unnatural movements.