The present study was conducted to examine the process of consolidation when learning a difficult bimanual coordination pattern. There are two phenomena associated with the process of consolidation, an enhancement in performance without additional practice and the stabilization observed as resistance to interference from a similar task after acquisition of a novel skill. Both phenomena have been widely examined in sequence skill learning studies. However, few studies have examined the consolidation effect after training of a continuous and rhythmic bimanual coordination pattern. The first goal of this study was to determine if sleep enhances the performance of a minimally trained 1:2 pattern of bimanual coordination in a manner that has been observed with sequencing skills, that is, performance significantly improves after an overnight sleep. A recent study by Buchanan & Wang (in-press) showed that by manipulating the position of a visual-augmented-feedback cursor, either behind or to-the-side of a 1:2 bimanual coordination template, an advantage of the side cursor position was found in the no-feedback retention test after a fifteen-minute break. The second goal was to test whether an overnight sleep may reduce the guidance effect associated with the behind cursor position as reported in Buchanan & Wang (in-press). In the present experiment, the effect of an overnight sleep on learning a 1:2 pattern of bimanual coordination was accessed with six test trials presented immediately (IMM group) or 24 hours (SLEEP group) after 5 minutes of practice. The test trials included three trials with feedback and three trials with feedback removed. For either the IMM or SLEEP group, half of the participants practiced with the behind cursor position and the other half practiced with the side cursor position. The results indicated that the SLEEP group showed an improvement in performance from the acquisition trials to the feedback test trials whereas the IMM group did not. The advantage of the side cursor position at the no-feedback retention test was not evident in the current study. These results are consistent with our two predictions and provide evidence of enhancement in learning a 1:2 pattern bimanual coordination skill.

Grasping and functionally interacting with a relatively large or awkwardly shaped object requires the independent and cooperative coordination of both limbs. Acknowledging the vital role of visual information in successfully executing any prehensile movements, the present study aimed to clarify how well existing bimanual coordination models (Kelso et al, 1979; Marteniuk & Mackenzie, 1980) can account for bimanual prehension movements targeting a single end-point under varying visual conditions. We therefore, employed two experiments in which vision of the target object and limbs was available or unavailable during a bimanual movement in order to determine the affects of visual or memory-guided control (e.g. feedback vs. feed forward) on limb coordination.<p>Ten right-handed participants (mean age = 24.5) performed a specific bimanual prehension movement targeting a solitary, static object under both visual closed loop (CL) and open loop 2s delay (OL2) conditions. Target location was varied while target amplitude remained constant. Kinematic data (bimanual coupling variables) indicated that regardless of target location, participants employed one of two highly successful movement execution strategies depending on visual feedback availability. During visual (CL) conditions participants employed a dominant-hand initiation strategy characterized by a significantly faster right-hand (RH) reaction time and simultaneous hand contact with the target. In contrast, when no visual feedback was available (OL2), participants utilized a search and follow strategy characterized by limb coupling at movement onset and a reliance on the dominant RH to contact the target ~62 ms before the left.<p>In conclusion, the common goal parameters of targeting a single object with both hands are maintained and successfully achieved regardless of visual condition. Furthermore, independent programming of each limb is undeniably evident within the behaviours observed providing support for the neural cross-talk theory of bimanual coordination (Marteniuk & Mackenzie, 1980). Whether movement execution is visually (CL) or memory-guided (OL2) there is a clear preference of RH utilization possibly due to its dynamic and/or hemispheric advantages in controlling complex motor behaviours (Gonzalez et al., 2006). Therefore, we propose that bimanual grasping to a solitary target is possibly governed globally by a higher-level structure and successful execution is achieved via independent spinal pathway modulation of limbs.

Grasping and functionally interacting with a relatively large or awkwardly shaped object requires the independent and cooperative coordination of both limbs. Acknowledging the vital role of visual information in successfully executing any prehensile movements, the present study aimed to clarify how well existing bimanual coordination models (Kelso et al, 1979; Marteniuk & Mackenzie, 1980) can account for bimanual prehension movements targeting a single end-point under varying visual conditions. We therefore, employed two experiments in which vision of the target object and limbs was available or unavailable during a bimanual movement in order to determine the affects of visual or memory-guided control (e.g. feedback vs. feed forward) on limb coordination.<p>Ten right-handed participants (mean age = 24.5) performed a specific bimanual prehension movement targeting a solitary, static object under both visual closed loop (CL) and open loop 2s delay (OL2) conditions. Target location was varied while target amplitude remained constant. Kinematic data (bimanual coupling variables) indicated that regardless of target location, participants employed one of two highly successful movement execution strategies depending on visual feedback availability. During visual (CL) conditions participants employed a dominant-hand initiation strategy characterized by a significantly faster right-hand (RH) reaction time and simultaneous hand contact with the target. In contrast, when no visual feedback was available (OL2), participants utilized a search and follow strategy characterized by limb coupling at movement onset and a reliance on the dominant RH to contact the target ~62 ms before the left.<p>In conclusion, the common goal parameters of targeting a single object with both hands are maintained and successfully achieved regardless of visual condition. Furthermore, independent programming of each limb is undeniably evident within the behaviours observed providing support for the neural cross-talk theory of bimanual coordination (Marteniuk & Mackenzie, 1980). Whether movement execution is visually (CL) or memory-guided (OL2) there is a clear preference of RH utilization possibly due to its dynamic and/or hemispheric advantages in controlling complex motor behaviours (Gonzalez et al., 2006). Therefore, we propose that bimanual grasping to a solitary target is possibly governed globally by a higher-level structure and successful execution is achieved via independent spinal pathway modulation of limbs.

no abstract provided / Thesis / Master of Science (MSc)

The purpose of this study was to investigate the influence of amplitude scaling on bimanual coordination in a circle drawing task. Eleven right-handed subjects traced the perimeter of 5 circles measuring 3, 6, 9, 12, and 15 cm in diameter under the following coordination conditions: (1) both hands move inward together (symmetric coordination pattern), and (2) both hands move counterclockwise together (asymmetric coordination pattern). In a set of self-paced trials, subjects traced each circle separately at a preferred frequency and separately for each coordination pattern. Although subjects matched the required amplitude of the target circles quite well, radial amplitude variability increased with increasing circle diameter. No transitions or movement reversals were observed in the self-paced trials, and the symmetric pattern was more stable than the asymmetric pattern. In a set of amplitude scaling trials, subjects continuously traced the 5 circles from small (3 cm) to big (15 cm) (SB) and from big to small (BS) at two fixed pacing frequencies (1.25 Hz and 1.5 Hz). Observed cycling frequency decreased with increasing circle diameter, and observed radial amplitude was most accurate when tracing the 9 cm diameter circle, with larger than required amplitude when tracing the 3 cm and 6 cm diameter circles, and smaller than required amplitude when tracing the 12 cm and 15 cm diameter circles. Radial amplitude variability also increased with increasing circle diameter in the amplitude scaling trials. The symmetric coordination pattern was more stable than the symmetric coordination pattern. Transitions from the asymmetric to symmetric coordination pattern as well as movement reversals were observed in both scaling directions. No transitions occurred while producing the symmetric pattern in any scaling direction or pacing frequency condition. The results show that amplitude scaling influenced the spatiotemporal aspects of bimanual circle drawing. Moreover, amplitude scaling induced more transitions than previous research that scaled movement frequency as a control parameter in bimanual circle drawing tasks.

Grasping is fundamentally important for our successful interaction with the environment. Grasping with both hands is phylogenetically older than the hand yet its underlying mechanisms are poorly understood. The objective of this research is to examine bimanual grasping and its underlying mechanisms. Two experiments were conducted to examine whether bimanual grasping involves both hemispheres equally or only one dominant hemisphere, and to examine whether information crosses at an early visual level and/or at later sensorimotor/motor levels. The first experiment examined participants’ grasping and reaching movements while they fixated either to the left or right of the object. For the second experiment, EEG data was recorded while participants performed a similar task. The results from both experiments suggested that when we grasp an object with both hands, the left and right hemispheres control the action equally, and visual information is shared before it reaches areas that are involved in motor control.

Grasping is fundamentally important for our successful interaction with the environment. Grasping with both hands is phylogenetically older than the hand yet its underlying mechanisms are poorly understood. The objective of this research is to examine bimanual grasping and its underlying mechanisms. Two experiments were conducted to examine whether bimanual grasping involves both hemispheres equally or only one dominant hemisphere, and to examine whether information crosses at an early visual level and/or at later sensorimotor/motor levels. The first experiment examined participants’ grasping and reaching movements while they fixated either to the left or right of the object. For the second experiment, EEG data was recorded while participants performed a similar task. The results from both experiments suggested that when we grasp an object with both hands, the left and right hemispheres control the action equally, and visual information is shared before it reaches areas that are involved in motor control.

The purpose of this study was to investigate the influence of amplitude scaling on bimanual coordination in a circle drawing task. Eleven right-handed subjects traced the perimeter of 5 circles measuring 3, 6, 9, 12, and 15 cm in diameter under the following coordination conditions: (1) both hands move inward together (symmetric coordination pattern), and (2) both hands move counterclockwise together (asymmetric coordination pattern). In a set of self-paced trials, subjects traced each circle separately at a preferred frequency and separately for each coordination pattern. Although subjects matched the required amplitude of the target circles quite well, radial amplitude variability increased with increasing circle diameter. No transitions or movement reversals were observed in the self-paced trials, and the symmetric pattern was more stable than the asymmetric pattern. In a set of amplitude scaling trials, subjects continuously traced the 5 circles from small (3 cm) to big (15 cm) (SB) and from big to small (BS) at two fixed pacing frequencies (1.25 Hz and 1.5 Hz). Observed cycling frequency decreased with increasing circle diameter, and observed radial amplitude was most accurate when tracing the 9 cm diameter circle, with larger than required amplitude when tracing the 3 cm and 6 cm diameter circles, and smaller than required amplitude when tracing the 12 cm and 15 cm diameter circles. Radial amplitude variability also increased with increasing circle diameter in the amplitude scaling trials. The symmetric coordination pattern was more stable than the symmetric coordination pattern. Transitions from the asymmetric to symmetric coordination pattern as well as movement reversals were observed in both scaling directions. No transitions occurred while producing the symmetric pattern in any scaling direction or pacing frequency condition. The results show that amplitude scaling influenced the spatiotemporal aspects of bimanual circle drawing. Moreover, amplitude scaling induced more transitions than previous research that scaled movement frequency as a control parameter in bimanual circle drawing tasks.

Orientador: Ana Maria Pellegrini / Banca: Sérgio Tosi Rodrigues / Banca: Cynthia Yukiko Hiraga / Resumo: A coordenação bimanual é um comportamento manifestado diariamente pelas pessoas na execução de tarefas do dia-a-dia. Controlar as duas mãos para varrer a casa, soltar pipa, costurar ou tocar piano são situações rotineiras que podem ser melhoradas e desempenhadas com precisão como resultado da prática. As tarefas unimanuais e as tarefas bimanuais que devem ser lideradas por uma das mãos, geralmente, são executadas apenas com a mão preferida, a mão direita para o maior número de pessoas. As ferramentas utilizadas nas tarefas do dia-a-dia são fabricadas para a mão direita e como conseqüência a diferença no desempenho é menor entre as mãos de pessoas com preferência manual esquerda. Manter um ritmo qualquer ou acertar alvos são tarefas que requeiram integridade de estruturas orgânicas, como por exemplo, os membros superiores e os sistemas visual e auditivo. O direcionamento da atenção visual pode ser muito importante na captura da informação para tocar alvos no plano horizontal, principalmente se as características espaciais e temporais das tarefas das duas mãos são diferentes. Contudo, as duas mãos estão separadas fisicamente e no desempenho em uma tarefa que requeira deslocamentos diferentes para as duas mãos o executante deve identificar a informação de uma das mãos para a execução precisa. O objetivo deste estudo foi verificar o efeito do direcionamento da atenção visual a uma das mãos no desempenho de uma tarefa bimanual com diferentes níveis de complexidade, em função da preferência manual. Pessoas com preferência manual direita e esquerda executaram uma tarefa de coordenação bimanual com deslocamentos dos membros superiores para o toque em um ou mais alvos que estavam igualmente distantes no plano horizontal e em intervalos temporais iguais ou diferentes. O direcionamento da atenção visual foi manipulado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Bimanual coordination is a behavior showed by people during the performance of many daily tasks. Actions that require the control of the hands as to sweep the room, to free pipe, to sew or to play piano are very common actions that can be improved and performed with accuracy as a result of practice. The unimanual tasks and the bimanual tasks that must be led by one of the hands, in general, are performed by the preferred hand, the right hand for a large number of individuals. Tools used in daily tasks are tailored for right hand and as a consequence the difference in performance between hands is smaller for those left-handed. To keep moving in a rhythm or to reach targets are tasks that require a full functioning of organic structures as the upper limbs or visual and auditory systems. The direction of visual attention can be very important in capturing relevant information for touching targets in the horizontal plane mainly if the characteristics of tasks of the two hands are different. However, the hands are physically apart and in the performance of a task that requires different displacements for the two hands the performer must pick up information from one of the hands for performance accuracy. The objective of the present study was to verify the effect of directing visual attention to one of the hands in the performance of bimanual tasks with different levels of complexity as a function of hand preference. Right- and left-handers performed a bimanual coordination task with displacement of the upper arms to reach one or more targets that were equally distant in the horizontal plane and in equal or different temporal intervals. The direction of visual attention was manipulated in three experimental conditions, in a condition directed to the right hand, in another to the left hand and in a third condition of free choice of the performer. The variables selected... (Complete abstract click electronic access below) / Mestre

The human hand is critically important for the performance of many activities of daily living (ADL). This dissertation used three human subject studies to investigate how different types of motor repetition interact with the process of sensorimotor adaptation and learning in complex dexterous manipulation tasks that depend on finger force control or bimanual coordination. Moreover, these investigations were conducted in both young adults (YA) and older adults (OA) to reveal the extent to which the process of aging may alter such interactions. In the first study, it was found that the repetition of simple ballistic force exertion allowed YA to better adapt to external mechanical perturbation with their dominant hand during fast object transport than the repetition of continuous movement. In contrast, OA were not differently affected by these two types of repetition training. In the second study, the effect of the same two repetition types on learning to perform an inverted pendulum balance task was examined. It was found that OA but not YA were able to balance the pendulum longer with the ballistic force repetition than the continuous movement repetition. In the last study, participants must move both hands to simultaneously follow moving targets. It was revealed that adaption to unilateral visual or mechanical constraints was driven by the dominant hand in YA, but OA were not able to adapt to these constraints. Together with additional findings about balance control and visual attention, these results on the effect of motor repetition provide new insights into the mechanisms underlying sensorimotor learning, which will support future studies to improve the efficacy of neurorehabilitation for dexterous manual functions.