Neuropsychologia 40 (2002) 1313–1323 Error correction strategies for motor behavior after unilateral brain damage: short-term motor learning processes Numa Dancause a,1 , Alain Ptito b , Mindy F. Levin a,c,d,∗ a Physiology Department, Neurological Sciences Research Center, University of Montreal, C.P. 6128, Succursale Centre-ville, Montreal, Que., Canada H3C 3J7 b Cognitive Neuroscience Unit, Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Que., Canada c School of Rehabilitation, University of Montreal, Montreal, Que., Canada d Research Center, Rehabilitation Instituteof Montreal, Montreal, Que., Canada Received 20 October 2000; received in revised form 2 November 2001; accepted 2 November 2001 Abstract In order to identify the mechanisms underlying motor impairments and motor learning following stroke-related brain damage, we analyzed correction strategies used by hemiparetic individuals to produce precise elbow flexion movements of the paretic arm and compared them to those of healthy individuals. Participants made rapid elbow flexion movements to a 6 ◦ wide target and were instructed to correct movement errors as quickly as possible when a spring-like load was unexpectedly introduced. Angular positions and torques before correction were used to identify error patterns. Results showed that participants with mild hemiparesis minimized movement errors within three trials, as did healthy participants. In contrast, severely affected individuals needed more trials to diminish errors and their movements were inconsistent. Participants with a moderate motor disability used both typical and atypical correction strategies. The differences in correction behaviors likely reflect deficits in arm motor function (r = 0.79) and executive function (r = 0.58) rather than levels of intellectual function (IQ ratings). Results indicate that the deficits that individuals with stroke experience when adapting their movements to changed load conditions may be due to difficulty in rapidly integrating visual and proprioceptive information. Deficits in executive function could also contribute to problems in producing accurate and consistent movements from trial to trial. Taken together, these results imply that all hemiparetic individuals would not benefit equally from the same motor re-training approaches. © 2002 Elsevier Science Ltd. All rights reserved. Keywords: Rehabilitation; Stroke; Motor control; Motor learning; Models; Short-term memory 1. Introduction Motor skill acquisition in healthy individuals is well documented. For example, repeated practice of even very simple movements, such as rapid single-joint elbow dis- placements to a target results in a decrease of movement time and an increase of peak velocity, both of which have been associated with motor learning [13]. In assuming that movement repetition leads to functional improvement in individuals with stroke-related brain damage as it does in healthy individuals, therapists encourage patients to prac- ∗ Corresponding author. Present address: IRM Site, Center for Interdis- ciplinary Research in Rehabilitation, Institut de r´ eadaptation de Montr´ eal, 6300 Av. Darlington, Montreal, Que., Canada H3S 2J4. Tel.: +1-514-340-2780; fax: +1-514-340-2154. E-mail address: levinm@poste.umontreal.ca (M.F. Levin). 1 Present address: Center on Aging and Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, MO, USA. tice different patterns of movement or different specific movements. However, well-controlled and systematic stud- ies of how new motor skills are acquired in patients with central nervous system (CNS) damage due to stroke are few and have mainly focused on the analysis of the effects of different treatment approaches on specific motor outcome measures [2,12,19,30,37]. There is little empirical evidence supporting the notion that the same type of motor learning as that seen in healthy individuals occurs in the hemiparetic arm of stroke patients. Indeed, some or all of the components necessary for the ac- quisition of new movements may be impaired after a stroke [31]. In addition, the presence of cognitive impairments may have considerable influence on adapting movements to new conditions since modification of the motor plan requires the integration, storage and use of sensory information from the previous movement for the initiation of subsequent move- ments. This plasticity of thought, which requires working memory within the domain of executive functions has been 0028-3932/02/$ – see front matter © 2002 Elsevier Science Ltd. All rights reserved. PII:S0028-3932(01)00218-4