Evaluating the Acute Contributions of Dopaminergic Replacement to Gait With Obstacles in Parkinson's Disease

The influence of dopaminergic replacement (DR) on gait in people with Parkinson's disease (PD) is well documented. However, little is known about the acute effects of dopamine on more complex locomotor tasks that require visual guidance to avoid obstacles during gait. The authors investigated the influence of DR on locomotor behavior in a task where movement planning and control might be challenged by the height of the obstacle. The PD group included patients diagnosed with idiopathic PD (n = 12), as well as healthy controls (n = 12). Patients walked and stepped over obstacles of different heights before (OFF) and after (ON) levodopa intake. Spatial adjustments were not modulated by DR, but the step time to perform these anticipatory gait adjustments was longer only in PD-OFF (compared with healthy controls) when approaching the highest obstacle, but not PD-ON. During the crossing phase, trail limb toe clearance of PD patients was shorter than healthy controls only during the OFF state. ON-OFF comparisons were significantly different only for the time to reach the lead foot clearance over the highest obstacle. In summary, DR partially improved movement slowness but did not directly affect movement amplitude of lower limb regulation in this gait task.     

Getting down and dirty: An exploration of participation in the field of obstacle challenges

This paper examines the contemporary phenomenon of obstacle challenges and why people participate in events that result in them getting soaking wet, freezing cold, and dirtier than they have ever been while also getting shot with pellets and receiving “electric shocks.” Many participants in these challenges have taken part numerous times and keep coming back for more. Using multiple research methods including questionnaires, participant observation where the author completed one of Ireland's more well‐known and “toughest physical and mental endurance challenges,” and also depth interviews with challenge participants has resulted in a rich and detailed account of the obstacle challenge experience. These events are so much more than a few hours of strenuous and muddy physical exercise. The sense of community and camaraderie that people experience during these challenges could be described as “transformative” with participants in many cases more rewarded and moved by this collaborative aspect than the gruelling physical endeavour that they undertake. The escapism provided by the experience is also one its main rewards, relief from the quotidian and the chance to just “be.” The servicescape proves to be critically important to the experience but in ways that are largely incompatible with research in this area to date in that the comfort and cleanliness expected of more traditional servicescapes are spurned and physical hardship is welcomed. As this is an exploratory and novel research topic, suggestions for further research are plentiful.     

Reach/Grasp Times with Lateral Reach Obstructions

When moving to grasp an object having adjacent obstacles that limit the space available for placing the fingers, the time for the reach/grasp is dependent on the distance of reaching and the space available for finger placement. Here we model the time taken in terms of these variables and develop mathematical models for the reach and grasp phases of the task and the location of obstacles. Data show that the movement to the target may be made under visual control and that, when the obstacles are close to the target object, a visually-controlled movement is made that is modeled by a modified form of Fitts' law. The time for the two components of the reach/grasp appear to be independent and linearly additive.