Multiple Practice Contexts to Reduce Context-dependent Learning in PD

Context-dependent learning (CDL) is a phenomenon that an individual demonstrates superior motor performance in the environmental context in which a task was originally learned and practiced, while the performance may decrease if carried out in a novel context. It has often been observed that after individuals with Parkinson's disease (PD) learned how to walk in a clinical setting, they appear to have difficulty generalizing the learned walking ability back to their home or community. To date, no effective intervention approaches have been designed to resolve this CDL for people with PD. One approach that could potentially reduce CDL is to practice a motor task in multiple contexts. Learning a task in multiple contexts would make the participants less likely to rely on the inconsistent ambient contextual information, and could facilitate the generation of stronger motor program and schema. No studies to date have investigated the effects of multiple practice contexts on reducing CDL in people with PD. It is also not clear the characteristics of the participants who would benefit from this type of intervention.

This study aims to investigate the effects of gait training in multiple practice contexts on CDL in individuals with PD. Additionally, this study aims to identify the characteristics of the participants who benefit from the intervention.

Sixty-four participants diagnosed with idiopathic PD will be recruited and randomized into 2 groups: Single-room and Two-room groups. The participants will receive 45 minutes of treadmill training and 15 minutes of over-ground gait training for 12 sessions. Throughout the training sessions, the Single-room group will practice walking in the same room, while the Two-room group will receive gait training in 2 distinct rooms. All participants will be assessed by a blinded evaluator before, immediately after, and 4 weeks after the intervention. The participants will undergo a series of cognitive, motor behavior, and neurophysiological examinations.

Group × time repeated measures analysis of variance (ANOVA) and the partial eta square (η2) will be calculated to determine the intervention effects on the outcome measures. Multiple linear regression analyses will be performed to determine the demographic, cognitive and motor behavior, and neurophysiological characteristics of participants who benefit from the proposed interventions.

Background: Recent evidence suggested that individuals with Parkinson's disease (PD) demonstrated greater context-dependency during motor learning than age-matched non-disabled adults. Context-dependent learning (CDL) is a phenomenon that an individual demonstrates superior motor performance in the environmental context in which a task was originally learned and practiced, while the performance may decrease if carried out in a novel context. It has often been observed that after individuals with PD learned how to walk in a clinical setting, they appear to have difficulty generalizing the learned walking ability back to their home or community. To date, no effective intervention approaches have been designed to resolve this CDL for people with PD.

One approach that could potentially reduce CDL is to practice a motor task in multiple contexts. Based on the research conducted with healthy young adults, learning a task in multiple contexts would make the participants less likely to rely on the inconsistent ambient contextual information. Multiple practice contexts could also facilitate the generation of stronger motor program and schema, leading to better transfer performance and less context-dependency. No studies to date have investigated the effects of multiple practice contexts on reducing CDL in people with PD. It is also not clear the characteristics of the participants who would benefit from this type of intervention.

Objectives: This study aims to investigate the effects of gait training in multiple practice contexts on CDL in individuals with PD. Additionally, this study aims to identify the characteristics of the participants who benefit from the intervention.

Methods: A total of 64 participants diagnosed with idiopathic PD will be recruited and randomized into 2 groups: Single-room and Two-room groups. The participants will receive one-on-one therapy including 45 minutes of treadmill training and 15 minutes of over-ground gait training for a total of 12 sessions. Throughout the 12 training sessions, the Single-room group will practice walking in the same room, while the Two-room group will receive gait training in 2 distinct rooms. All participants will be assessed by a blinded evaluator before, immediately after, and 4 weeks after the intervention. The participants will undergo a series of cognitive, motor behavioral, and neurophysiological examinations. Cognitive assessments will include measures of CDL, Montreal Cognitive Assessment, and the Stroop Color-Word test. Motor behavioral measures will include the Unified Parkinson's Disease Rating Scale, five times sit-to-stand test, 10-meter walk test, timed up and go test, the Activities-Specific Balance Confidence Scale, and Parkinson's Disease Questionnaire-39. Neurophysiological outcomes will be examined with transcranial magnetic stimulation to determine the changes in corticomotor excitability associated with the interventions.

Group × time repeated measures analysis of variance (ANOVA) and the partial eta square (η2) will be calculated to determine the intervention effects on the outcome measures. Multiple linear regression analyses will be performed to determine the demographic, cognitive and motor behavior, and neurophysiological characteristics of participants who benefit from the proposed interventions.

Eligibility Criteria:
Inclusion Criteria:

* able to follow instructions to perform the tasks (Mini Mental State Examination ≥ 24)
* able to read and hear properly without or with aids (e.g., eyeglasses or hearing aids)
* can walk independently with or without devices

Exclusion Criteria:

* has other neurological disorders in addition to PD
* has deep brain stimulation or pacemaker implanted in their body
* has a family-history of epilepsy
* has a self-history of seizure
* has unstable medical conditions