Parkinson’s disease (PD) is a progressive neurodegenerative disorder resulting from a loss of multisystem degenerations and neurotransmitter deficiencies such as dopaminergic and cholinergic degenerations –. The degenerations lead to typical clinical manifestation in people with PD is primarily motor functions such as postural instability, impairments in gait, rigidity, tremor, and bradykinesia , –, but also a wide range of cognitive dysfunctions such as deficits in executive functions and visuospatial processing –. These symptoms exacerbate as the disease progresses and lead to declines in locomotion and high risk of falls , , –. Among individuals with PD, 5068% of them experience one or more falls every year related to walking , , , . Moreover, PD results in a disturbance in the ability to negotiate obstacles due to difficulties in gait initiation, switching locomotor commands, or adapting to perturbations. These difficulties are related to high risk of falls. Therefore, typical walking rehabilitation for people with PD focuses on obstacle negotiation training in the clinic , . Despite multisystem involvement in PD, dopamine replacement therapy (DRT) is a standard treatment to alleviate many PD-related motor symptoms such as bradykinesia, rigidity, and tremor. Other motor symptoms such as gait impairments and postural instability, however, are not well responsive to DRT. Moreover, DRT may cause impairments on relatively intact structures in the early stages of PD , . The relationship between the level of dopamine and its performance works in the inverted U-shape relationship such that there is an optimal level of dopamine to function its optimal performance. Therefore, both a lack of or excessive level of dopamine can cause impaired performance . This is referred to as an overdose hypothesis. The neural structures such as the caudate nucleus and ventral striatum, which is less affected by dopamine depletion, are important motor skill acquisition and motivational contributions to motor learning –. Therefore, the overdose effect may negatively alter the process of motor learning during gait in people with PD . In addition, people with PD often have difficulty executing acquired motor skills in different contexts –. More strikingly, the problem executing the skill also occurs when seemingly irrelevant contextual cues (i.e., incidental context) such as a background color of the scene are different , . This challenge is commonly referred to as context-dependent learning (CDL) . CDL is defined as superior retention of learned skills when retention is performed in the same context as the training . Over-reliance on irrelevant contextual cues may limit the generalization of learned skills. Although CDL has been observed during upper extremity tasks in people with PD, limited evidence for CDL during locomotion exists. Consequently, it is crucial to understand the effect of PD on context-dependent locomotor learning. Here, the goal of this project was to assess the influence of PD on locomotor skill learning and CDL using immersive virtual reality (VR). Recent advances in technology have allowed us to use cost-effective and high-quality VR to investigate motor tasks that are difficult to create in typical clinical environments–. Therefore, we aimed to develop a task in VR to investigate obstacle negotiation skill learning in people with PD and age-matched controls and to determine how environmental context affects retention performance
Kim, Aram, "Using immersive virtual reality to assess context-dependency of locomotor skill learning in people with Parkinson's disease" (2019). Link Foundation Modeling, Simulation and Training Fellowship Reports. 2.