Neurological Rehabilitation

Thehumanmotor systemhas the capacity to learn through practice and experience. Motor learning is a loosely defined term that encompassesmotor adaptation, skill acquisition, anddecision-making (Shadmehr andWise, 2005; Krakauer, 2006; Krakauer and Mazzoni, 2011; Wolpert et al., 2011). This chapter will focus on what we, and others, consider to be twodistinct types ofmotor learning (Agostino et al., 1996; Huang and Krakauer, 2009; Reis et al., 2009;Krakauer andMazzoni, 2011; Shmuelof etal., 2012): adaptation and skill acquisition. In adaptation, the motor system responds to altered environmental conditions to regain a former level of performance in the new setting. For example,when one first puts on prismgoggles and attempts to reach to a target, there is a misalignment between the actual and visually perceived position of the target, resulting in reach errors. Through adaptation, the discrepancy between the predicted position of the arm at the end of the reaching movement and the observed positionof the arm is gradually reduceduntil one can reach the target as well as one could before putting on the goggles. Adaptation can therefore be understood as the learning of a new relationship betweenwell-learnedmovements and a new spatial goal (Krakauer, 2009). In contrast, skill learning (e.g., learning to ride a bike or to play tennis) involves acquiring new patterns ofmuscle activation and achieving a higher level of performance by reducing errorswithout a reduction inmovement speed (Hallett andGrafman, 1997; Reis et al., 2009; Shmuelof et al., 2012). This chapter will first review the basic principles underlying motor adaptation and skill learning, with a focus on studies involving the upper extremity, although similar principles are likely to underlie learning with the lower extremity. The second part of the chapter will discuss the relevance of these learning principles to neurorehabilitation for stroke patients and their application through rehabilitative techniques.