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.

This thesis investigates human behaviour when controlling Six Degree of Freedom (DoF) Interfaces. A substantial literature review forms the basis for the design of an experimental framework. An assertion is made which states that effective control interfaces will support a broad range of activity in a virtual environment. A review of motor control facilitates the design of a set of appropriate tasks and measures A series of seven experiments are presented. The series of experiments are [sic] partitioned into three studies: Object Rotation in 3DoF (three experiments); Object Manipulation in 6DoF (three experiments); Egomotion in a 3D environment (one experiment). A new rotation controller which maps 2D mouse input to 3DoF rotation is designed and implemented. It is then compared against an "integrated" 6DoF controller. The purpose of these studies is to establish an experimental paradigm that will enable designers to examine operator strategies with input devices and interfaces. From the experiments described in the studies a number of conclusions are made: (1) operator strategies cannot be identified by single measures—rather a variety of measures help disambiguate singular performance scores; (2) control strategies can be employed due to the characteristics of one interface component but can leak into behaviour with other interface components which are related in terms of the task; (3) a variety of tasks must be employed to develop a rich picture of operator behaviour with a particular interface; (4) certain characteristics of an interface can mask other performance issues when comparing interfaces; (5) travel can be analysed with a traditional tracking task; (6) the control structure of the interface must match the control structure of the task domain—if this is exceeded then in some cases performance can actually be degraded.

Reaching with altered visual feedback of the hand’s position in a virtual environment leads to reach adaptation in the trained hand, and also in the untrained hand (Wang & Sainburg, 2002). In the current study, we asked if reach adaptation in the untrained (right) hand is due to transfer of explicit (i.e., EA; conscious strategy) and/or implicit adaptation (i.e., IA; unconscious) from the left (trained) hand, and if the transfer of EA and IA changes depending on how one is made aware of the visuomotor distortion. We further asked if EA and IA are retained in the trained and untrained hand for 24 hours. Participants (n=60) were evenly divided into 3 groups (Strategy, No-Strategy, and Control). All participants reached to visual targets while seeing a cursor on the screen that was rotated 40° clockwise relative to their hand motion. Participants in the Strategy group were instructed on how to counteract the visuomotor distortion. The No-Strategy group was not told of the upcoming visuomotor distortion but was later asked to reach while engaging in any strategy they had learned in order to assess EA. Participants in the Control group were also not told of the upcoming visuomotor distortion and were never instructed to engage in any strategy when reaching. EA and IA were assessed in both the trained and untrained hands immediately following rotated reach training, and 24 hours later by having participants reach without the cursor when instructed to: (1) aim so that your hand lands on the target (to assess IA) and (2) use what was learned during training so that the cursor lands on the target (to assess EA + IA; exception of Control group). Results revealed that the groups differed with respect to the extent of reach adaptation achieved when initially training with the rotated cursor, such that the Strategy group had greater EA and less IA compared to the No-Strategy group in the trained hand. Unexpectedly, the Control group also showed less IA compared to the No-Strategy group, but was similar to the Strategy group. For both the Strategy and No-Strategy groups, EA was transferred between hands and was retained over time. While the extent of IA varied between groups in the trained (left) hand immediately following reach training trials, significant transfer of IA was not found in any of the three groups. Retention of IA was observed in the trained hand but decayed over testing days. Together, these results suggest that while initial EA and IA in the trained hand is dependent on how one is made aware of the visuomotor distortion, transfer and retention of visuomotor adaptation is driven almost exclusively by EA, regardless of instructions provided.

In the absence of treatment following strokes, both humans and model organisms demonstrate partial improvements in motor function. Several endogenous mechanisms, such as cortical reorganization, are hypothesized to cause this spontaneous biological recovery. Reorganization of the motor cortex occurs within a time sensitive period and involves both proximal and distal sites of the intact brain. Despite these advancements, whether the same or different cells are used in the reorganized cortex after stroke remains unknown. In order to identify the motor networks involved in recovery, our lab has begun using the inducible Arc-CreERᵀ²:Rosa-YFPᶠᐟᶠ mice. In conjunction with the bimanual string-pulling task, this inducible model allows for the labelling of active cells throughout stroke recovery; either pre, 2 days post-stroke (dps) and 2 weeks post-stroke (wps). Behavioural deficits on the string-pull task were observed at 2 dps and accompanied by a decrease in active cells in the ipsilesional secondary motor (M2) cortex of stroke mice. By 2 wps, stroke mice had partial recovery of motor function with no differences in active cells in the ipsilesional M2. Interestingly, ~40% of cell in the motor cortex of sham and stroke mice were activated more than once while performing the string-pull task until 2 wps. Deeplabcut kinematic analysis of the string-pull task was also unable to identify differences in motor performance between stroke and sham mice. In addition, irrelevant of stroke injuries, only 60% of cells co-expressed the pan-neuronal marker NeuN after surgeries. Together these findings suggest that 40% of cells are reactivated up to 2 weeks post-stroke during the performance of a motor task, despite the acute decreases in active cells in the ipsilesional M2 of stroke mice. DeepLabCut kinematic results also highlight the need to redefine kinematic outcomes to better assess the full spectrum of stroke deficits.

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

<p> This study was designed to examine three issues concerning the learning of a new coordination pattern. The first issue examined was the root of the conflicting findings of previous work concerning the effect of learning a novel coordination pattern on the performance an intrinsically stable antiphase pattern (Fontaine, Lee, & Swinnen, 1997; Lee, Verschueren & Swinnen, 1995; Zanone & Kelso, 1992). Consideration of these experiments revealed that different metronomes were used, and that this metronome difference is critical because it may have influenced the learners' attentional focus during learning. Therefore, the present experiment sought to examine whether a difference of attentional focus was the cause of this conflict. The second issue was whether the superiority of an external focus over internal focus of attention during learning would be evident in the learning of a new coordination pattern. And last, this study set out to examine the issue of prior learning of a bimanual coordination pattern on the learning of a new coordination pattern. Two groups of participants (one with an. internal focus of attention, and the other with an external focus of attention) learned to perform a 90° relative phase (RP) coordination pattern over two practice sessions, and were then asked to perform a 135° RP pattern in a third session. An additional two groups of participants (one with an internal focus of attention, and the other with an external focus of attention), served as controls, and learned to perform the 135° RP pattern over all three sessions. Results of this experiment did not support the hypothesis that a difference in attentional focus during learning is responsible for the conflicting findings concerning the effect of learning on intrinsic pattern performance. Although the results seem to indicate that an external focus of attention is more beneficial than an internal focus of attention during learning of a new coordination pattern, further work without feedback as a confounding factor is required. Finally, results show that prior learning does influence the learning of a new coordination pattern in that positive transfer of learning was evident (prior learning of the 90° pattern facilitated performance of the 135° pattern), and findings provide evidence for the creation of a new attractor with learning. </p> / Thesis / Master of Science (MSc)

Estudos prévios têm indicado a capacidade de aprender diferentes movimentos simultaneamente, sugerindo que a aprendizagem motora pode ocorrer a partir de uso parcial de recursos atencionais. Porém, não se conhece a extensão em que a aprendizagem em tarefas motoras duais é afetada pela distribuição da atenção entre as tarefas durante a prática. O objetivo deste estudo foi avaliar o efeito da distribuição de diferentes proporções da atenção a cada componente de uma tarefa motora dual durante a prática sobre sua aprendizagem e automatização. Participaram deste estudo 35 estudantes universitários, destros, que realizaram as seguintes tarefas: traçar uma estrela baseada em feedback visual invertido com a mão esquerda e realizar toques sequenciais dos dedos com a mão direita. A execução simultânea das duas tarefas correspondeu à tarefa dual. Para estimar a demanda de atenção para execução das tarefas foi realizada a medida de tempo de reação probatório com estímulo auditivo e resposta vocal. Os participantes foram divididos em três grupos: prática na tarefa dual com distribuição assimétrica de atenção, alocando maior atenção à tarefa de traçado de estrela e mínima atenção à tarefa de toques dos dedos (Dass); prática na tarefa dual com atenção distribuída simetricamente entre ambas as tarefas (Dsim); e prática na tarefa singular, com prática exclusiva na tarefa de traçado (Sing). Os resultados mostraram que os três grupos diminuíram o tempo de reação probatório nos desempenhos das tarefas singulares e dual, indicando ganho de automatização com a prática. Na tarefa de toques dos dedos, os grupos Dsim e Dass tiveram melhor desempenho do que o grupo Sing, indicando que esta tarefa foi aprendida com baixa alocação de atenção. Na tarefa de traçado de estrela, os três grupos melhoraram de forma similar o desempenho com a prática. A avaliação na tarefa dual revelou que ambos os grupos de prática na tarefa dual, independentemente da distribuição de atenção, tiveram melhor desempenho após a prática em relação ao grupo Sing. Não foram encontradas diferenças entre os grupos Dsim e Dass tanto para a tarefa de toques dos dedos quanto para a tarefa de traçado de estrela, indicando que estas tarefas foram aprendidas de forma equivalente para diferentes regimes de distribuição de atenção. Estes resultados sugerem que a melhora de desempenho com a prática, e automatização de movimentos associada, pode ser atingida com alocação de recursos atencionais parciais durante a prática na tarefa / Previous studies have indicated the human ability to learn different movements simultaneously, suggesting that motor learning can be achieved from partial use of attentional resources. However, the extent to which learning dual motor tasks is affected by the distribution of attention between tasks during practice is unknown. The aim of this study was to evaluate the effect of distribution of different proportions of attention to each component of a dual motor task during practice on its learning and automaticity. Thirty-five right-handed university students participated of the study. They performed the following tasks: drawing of a star-shaped figure based on inverted visual feedback with their left hand and sequentially touching the fingers with their right hand. The dual task consisted of the simultaneous execution of the two tasks. To evaluate movement\'s automatization due to practice, we used a probe reaction time task consisting of an auditory stimulus and a vocal response. Participants were assigned to one of three groups: practice of the dual task with asymmetric distribution of attention, allocating major attentional resources to the star drawing task and minimal attention to the fingers touching task (Dasy); practice of the dual task with symmetric distribution of attention between both tasks (Dsym); and practice of the single star drawing task (Sing). Results showed that after practice, the probing reaction time was reduced in the performance of the single and dual tasks in all groups, indicating augmented automaticity after practice. In the fingers touching task, the Dsym and Dasy groups outperformed the Sing group, indicating that this task was learned with reduced attention. In the star drawing task, the three groups improved similarly their performance after practice. Evaluation of the dual task revealed that both dual task practice groups, independently of the attention distribution regime, performed better than the Sing group after practice. No differences were found between the Dsym and Dasy groups across tasks, suggesting that they learned to a similar extent both tasks regardless of the attention distribution regime. These results suggest that performance improvement from practice, and associated movements automatization, can be achieved with allocation of partial attentional resources during the task acquisition

Estudos prévios têm indicado a capacidade de aprender diferentes movimentos simultaneamente, sugerindo que a aprendizagem motora pode ocorrer a partir de uso parcial de recursos atencionais. Porém, não se conhece a extensão em que a aprendizagem em tarefas motoras duais é afetada pela distribuição da atenção entre as tarefas durante a prática. O objetivo deste estudo foi avaliar o efeito da distribuição de diferentes proporções da atenção a cada componente de uma tarefa motora dual durante a prática sobre sua aprendizagem e automatização. Participaram deste estudo 35 estudantes universitários, destros, que realizaram as seguintes tarefas: traçar uma estrela baseada em feedback visual invertido com a mão esquerda e realizar toques sequenciais dos dedos com a mão direita. A execução simultânea das duas tarefas correspondeu à tarefa dual. Para estimar a demanda de atenção para execução das tarefas foi realizada a medida de tempo de reação probatório com estímulo auditivo e resposta vocal. Os participantes foram divididos em três grupos: prática na tarefa dual com distribuição assimétrica de atenção, alocando maior atenção à tarefa de traçado de estrela e mínima atenção à tarefa de toques dos dedos (Dass); prática na tarefa dual com atenção distribuída simetricamente entre ambas as tarefas (Dsim); e prática na tarefa singular, com prática exclusiva na tarefa de traçado (Sing). Os resultados mostraram que os três grupos diminuíram o tempo de reação probatório nos desempenhos das tarefas singulares e dual, indicando ganho de automatização com a prática. Na tarefa de toques dos dedos, os grupos Dsim e Dass tiveram melhor desempenho do que o grupo Sing, indicando que esta tarefa foi aprendida com baixa alocação de atenção. Na tarefa de traçado de estrela, os três grupos melhoraram de forma similar o desempenho com a prática. A avaliação na tarefa dual revelou que ambos os grupos de prática na tarefa dual, independentemente da distribuição de atenção, tiveram melhor desempenho após a prática em relação ao grupo Sing. Não foram encontradas diferenças entre os grupos Dsim e Dass tanto para a tarefa de toques dos dedos quanto para a tarefa de traçado de estrela, indicando que estas tarefas foram aprendidas de forma equivalente para diferentes regimes de distribuição de atenção. Estes resultados sugerem que a melhora de desempenho com a prática, e automatização de movimentos associada, pode ser atingida com alocação de recursos atencionais parciais durante a prática na tarefa / Previous studies have indicated the human ability to learn different movements simultaneously, suggesting that motor learning can be achieved from partial use of attentional resources. However, the extent to which learning dual motor tasks is affected by the distribution of attention between tasks during practice is unknown. The aim of this study was to evaluate the effect of distribution of different proportions of attention to each component of a dual motor task during practice on its learning and automaticity. Thirty-five right-handed university students participated of the study. They performed the following tasks: drawing of a star-shaped figure based on inverted visual feedback with their left hand and sequentially touching the fingers with their right hand. The dual task consisted of the simultaneous execution of the two tasks. To evaluate movement\'s automatization due to practice, we used a probe reaction time task consisting of an auditory stimulus and a vocal response. Participants were assigned to one of three groups: practice of the dual task with asymmetric distribution of attention, allocating major attentional resources to the star drawing task and minimal attention to the fingers touching task (Dasy); practice of the dual task with symmetric distribution of attention between both tasks (Dsym); and practice of the single star drawing task (Sing). Results showed that after practice, the probing reaction time was reduced in the performance of the single and dual tasks in all groups, indicating augmented automaticity after practice. In the fingers touching task, the Dsym and Dasy groups outperformed the Sing group, indicating that this task was learned with reduced attention. In the star drawing task, the three groups improved similarly their performance after practice. Evaluation of the dual task revealed that both dual task practice groups, independently of the attention distribution regime, performed better than the Sing group after practice. No differences were found between the Dsym and Dasy groups across tasks, suggesting that they learned to a similar extent both tasks regardless of the attention distribution regime. These results suggest that performance improvement from practice, and associated movements automatization, can be achieved with allocation of partial attentional resources during the task acquisition

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.