The authors examined the effects of the degree of impairment of the contralesional upper limb and the side of the hemispheric damage on ipsilesional upper limb performance in chronic stroke individuals. Right- and left-side stroke resulting in mild-to-severe impairment and healthy participants took part in simple and choice reaction time tasks involving aiming movements. The stroke individuals performed the aiming movements with the ipsilesional upper limb using a digitizing tablet to ipsi- or contralateral targets presented in a monitor. The global performance of the group with severe right hemispheric damage was worse than that of the other groups, indicating that the side of hemispheric damage and degree of motor impairment can adversely affect aiming movement performance.

Aiming movements are part of daily activities but the brain hemispheres' role in targeted aiming sequential movements is not fully clear. Start and execution of discrete and sequential tasks toward targets were analyzed in 10 individuals with left-hemisphere damage, 10 right-hemisphere-damaged, and 10 healthy ones. Arm movements were performed over a digitizing tablet, following stimuli on a monitor, from initial position toward right and left-positioned targets. Poststroke individuals used their ipsilesional arm and healthy individuals, both arms. Right-hemisphere-damaged individuals showed higher reaction time and left-hemisphere-damaged individuals, lower smoothness. Due to spatial demand of tasks, the right hemisphere played a major role in movement planning, while the left, in movement execution.

Abstract--The purpose of this study was to analyze the influence of the uncertainty of target location on the planning and execution of aiming movements performed towards the ipsilateral and contralateral directions by the right and left upper limbs. In addition, the association between the performance of aiming movements and the performance of functional manual tasks was investigated. Two tasks were proposed: with prior knowledge of the movement direction (simple reaction time) or not (choice reaction time). The grip strength and manual dexterity were measured. The choice option in response (i.e. uncertainty) influenced planning of the aiming movements, but not its execution, while movements performed towards the contralateral direction were worse in execution as compared to the ipsilateral direction. Manual dexterity was significantly correlated with reaction times, while the performance during movement execution was significantly correlated with handgrip/pinch strength.Keywords: behavior, upper extremity, functional laterality, reaction time Resumo--"Incerteza de movimentos dirigidos ao alvo e sua associação com a função manual." O objetivo desse estudo foi avaliar a influência da incerteza da localização do alvo no planejamento e execução de movimentos dirigidos ao alvo realizados para as direções ipsilateral e contralateral pelos membros superiores direito e esquerdo. Em adição, a associação entre o desempenho do movimento dirigido ao alvo e o desempenho em tarefas manuais funcionais foi investigada. Duas tarefas foram propostas: com o conhecimento prévio da direção do movimento (tempo de reação simples) ou não (tempo de reação de escolha). Foram avaliadas a força de preensão palmar e a destreza manual. A opção de escolha na resposta (ex. incerteza) influenciou o planejamento do movimento dirigido ao alvo, mas não a sua execução, enquanto os movimentos realizados para a direção contralateral apresentaram pior execução quando comparados à direção ipsilateral. Destreza manual foi significativamente correlacionada com tempos de reação, enquanto o desempenho durante a execução do movimento foi significativamente correlacionado com forças de preensão/pinça. Palavras-chave: comportamento, membro superior, lateralidade funcional, tempo de reação Resumen--"La incertidumbre de movimientos dirigidos a la diana y su asociación con la función manual." El propósito de este estudio fue evaluar la influencia de la incertidumbre ubicación de la diana en la planificación y ejecución de movimientos dirigidos a la diana realizado por direcciones ipsilateral y contralateral por los miembros superiores derecho e izquierdo. Además, se investigó la asociación entre el rendimiento de movimiento dirigido a la diana y el rendimiento de la mano para tareas funcionales. Se propusieron dos tareas: con el conocimiento previo de la dirección del movimiento (tiempo de reacción simple) o no (tiempo de reacción del elección). Se evaluó la fuerza de prensión y la destreza manual. La opción de elección en responder (Incertidumbre por ejemplo....