The adaptive process of motor learning by stroke survivors as a function of task complexity

This study investigated the effects of task complexity on the adaptive process of motor learning by stroke survivors considering the side (hemisphere) of injury, level of cognitive impairment, time since injury, and participants’ age. They were 28 stroke survivors, volunteers, with lesions in the right ( n = 14) and left ( n = 14) hemispheres, aged between 37 and 75 years, with time since injury between 0.5 and 16.7 years, and classified on the MoCA test between 10 and 28. The learning task involved demands of sequential movements and coincident timing performed on a computer. Participants had to click the mouse cursor on two (simple task) or three (complex) targets to that the last click coincided, in a certain location (coincidence zone), with a moving ball. The practice comprised the following sequential phases: stabilization 1 (140 trials), adaptation 1 (10 trials), stabilization 2 (30 trials), and adaptation 2 (10 trials). The dependent variables were the absolute and variable errors, which were analyzed considering the first and last blocks of trials in the stabilization phases and the blocks of the adaptation phases. The results showed that: (i) task complexity affected the adaptive process of motor learning by stroke survivors, regardless of the hemisphere of the lesion, level of cognitive impairment, time since the lesion, and age; (ii) stroke survivors adapted themselves to perturbation in simple and complex tasks by parameterizing and structure reorganizing, respectively; and (iii) stroke survivors were able to explore the micro-redundancy when practicing the simple task.