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Movement corrections to somatosensory targets have been found to be shorter in latency and larger in magnitude than corrections to external visual targets. Somatosensory targets (e.g., body positions) can be identified using both tactile (i.e., skin receptors) and proprioceptive information (e.g., the sense of body position derived from sensory organs in the muscles and joints). Here, we investigated whether changes in tactile information alone, without changes in proprioception, can elicit shorter correction latencies and larger correction magnitudes than those to external visual targets. Participants made reaching movements to a myofilament touching the index finger of the non-reaching finger (i.e., a tactile target) and a light-emitting diode (i.e., visual target). In one-third of the trials, target perturbations occurred 100 ms after movement onset, such that the target was displaced 3 cm either away or toward the participant. We found that participants demonstrated larger correction magnitudes to visual than tactile target perturbations. Moreover, we found no differences in correction latency between movements to perturbed tactile and visual targets. Further, we found that while participants detected tactile stimuli earlier than visual stimuli, they took longer to initiate reaching movements to an unperturbed tactile target than an unperturbed visual target. These results provide evidence that additional processes may be required when planning movements to tactile versus visual targets and that corrections to changes in tactile target positions alone may not facilitate the latency and magnitude advantages observed for corrections to somatosensory targets (i.e., proprioceptive-tactile targets).

BACKGROUND: The burden of post-stroke cognitive impairment, as well as affective disorders, remains persistently high. With improved stroke survival rates and increasing life expectancy, there is a need for effective interventions to facilitate remediation of neurocognitive impairments and post-stroke mood disorders. OBJECTIVE: To investigate the effects of Therapeutic Instrumental Music Performance (TIMP) training with and without Motor Imagery on cognitive functioning and affective responding in chronic post-stroke individuals. METHODS: Thirty chronic post-stroke, community-dwelling participants were randomized to one of three experimental arms: (1) 45 minutes of active TIMP, (2) 30 minutes of active TIMP followed by 15 minutes of metronome-cued motor imagery (TIMP+cMI), (3) 30 minutes of active TIMP followed by 15 minutes of motor imagery without cues (TIMP+MI). Training took place three times a week for three weeks, using a selection of acoustic and electronic instruments. Assessments, administered at two baselines and post-training, included the Trail Making Test (TMT) - Part B to assess mental flexibility, the Digit Span Test (DST) to determine short-term memory capacity, the Multiple Affect Adjective Checklist - Revised (MAACL-R) to ascertain current affective state, and the General Self-Efficacy Scale (GSE) to assess perceived self-efficacy. The Self-Assessment Maniqin (SAM) was also administered prior to and following each training session. RESULTS: Thirty participants completed the protocol, ten per arm [14 women; mean age = 55.9; mean time post-stroke = 66.9 months]. There were no statistically significant differences between pooled group baseline measures. The TIMP+MI group showed a statistically significant decrease in time from pre-test 2 to post-test on the TMT. The TIMP group showed a significant increase on MAACL sensation seeking scores, as well as on the Valence and Dominance portions of the SAM; TIMP+cMI showed respective increases and decreases in positive and negative affect on the MAACL, and increases on the Valence, Dominance, and Arousal portions of the SAM. No statistically significant association between cognitive and affective measures was obtained. CONCLUSIONS: The mental flexibility aspect of executive functioning appears to be enhanced by therapeutic instrumental music training in conjunction with motor imagery, possibly due to multisensory integration and consolidation of representations through motor imagery rehearsal following active practice. Active training using musical instruments appears to have a positive impact on affective responding; however, these changes occurred independently of improvements to cognition.

During reaching and grasping movements tactile processing is typically suppressed. However, during a reception or catching task, the object can still be acquired but without suppressive processes related to movement execution. Rather, tactile information may be facilitated as the object approaches in anticipation of object contact and the utilization of tactile feedback. Therefore, the current study investigated tactile processing during a reception task. Participants sat with their upper limb still as an object travelled to and contacted their fingers. At different points along the object’s trajectory and prior to contact, participants were asked to detect tactile stimuli delivered to their index finger. To understand if the expectation of object contact contributed to any modulation in tactile processing, the object stopped prematurely on 20% of trials. Compared to a pre-object movement baseline, relative perceptual thresholds were decreased throughout the object’s trajectory, and even when the object stopped prematurely. Further, there was no evidence for modulation when the stimulus was presented shortly before object contact. The former results suggest that tactile processing is facilitated as an object approaches an individual’s hand. As well, we purport that the expectation of tactile feedback drives this modulation. Finally, the latter results suggest that peripheral masking may have reduced/abolished any facilitation.

A remote visual distractor increases saccade reaction time (RT) to a visual target and may reflect the time required to resolve conflict between target- and distractor-related information within a common retinotopic representation in the superior colliculus (SC) (i.e., the remote distractor effect: RDE). Notably, because the SC serves as a sensorimotor interface it is possible that the RDE may be associated with the pairing of an acoustic distractor with a visual target; that is, the conflict related to saccade generation signals may be sensory-independent. To address that issue, we employed a traditional RDE experiment involving a visual target and visual proximal and remote distractors (Experiment 1) and an experiment wherein a visual target was presented with acoustic proximal and remote distractors (Experiment 2). As well, Experiments 1 and 2 employed no-distractor trials. Experiment 1 RTs elicited a reliable RDE, whereas Experiment 2 RTs for proximal and remote distractors were shorter than their no distractor counterparts. Accordingly, findings demonstrate that the RDE is sensory specific and arises from conflicting visual signals within a common retinotopic map. As well, Experiment 2 findings indicate that an acoustic distractor supports an intersensory facilitation that optimizes oculomotor planning.

It has been argued that exercise-induced muscle fatigue and tendon vibration can alter proprioceptive estimates of limb position. While exercise-induced muscle fatigue may also affect central efferent processes related to limb position sense, tendon vibration specifically targets peripheral afferent signals. It is unclear, however, whether either of these perturbations (i.e., muscle fatigue or tendon vibration) can alter the multisensory weighting processes preceding goal-directed movements. The current study sought to specifically explore visual-proprioceptive weighting before or after eccentric exercise-induced antagonist muscle fatigue (experiment 1) versus with or without intertrial simultaneous agonist-antagonist tendon vibration (experiment 2). To assess sensory weighting, a visual-proprioceptive mismatch between the participant’s actual initial starting position and the associated visual cursor position was employed. This method provides an estimate of the participant’s reliance on the proprioceptive or visual starting limb position for their aiming movements. Although there was clear evidence of muscle fatigue, there was no systematic alteration of proprioceptive weighting after eccentric exercise and no relationship between sensory weighting and the level of fatigue. On the other hand, participants’ reliance on their actual (proprioceptive) limb position was systematically reduced when exposed to agonist-antagonist tendon vibration before each aiming movement. These findings provide seminal evidence that intertrial tendon vibration, but not exercise-induced fatigue, can alter the reliability of proprioceptive estimates and the relative contributions of visual and proprioceptive information for goal-directed movement. NEW & NOTEWORTHY Previous work has used muscle fatigue or tendon vibration to perturb proprioceptive limb position estimates. This study sought to determine whether exercise-induced muscle fatigue versus intertrial tendon vibration can alter multisensory weighting for upper limb-aiming movements. By introducing a discrepancy between participants’ actual proprioceptive and visual finger position, this study provides seminal evidence for the reduction of proprioceptive-to-visual weighting using intertrial tendon vibration but no evidence for a systematic reduction following exercise-induced fatigue.

Brief windows of vision presented during reaching movements contribute to endpoint error estimates. It is not clear whether such error detection processes depend on other sources of information (e.g., proprioception and efference). In the current study, participants were presented with a brief window of vision and then judged whether their movement endpoint under- or over-shot the target after: 1) performing an active reach; 2) being passively guided by a robotic arm; and 3) observing a fake hand moved by the robot arm. Participants were most accurate at estimating their endpoint error in the active movement conditions and least accurate in the action observation condition. Thus, both efferent and proprioceptive information significantly contribute to endpoint error detection processes even with brief visual feedback.

Background: Older and younger adults utilize sensory information differently to plan and control their reaching movements to visual targets. In addition, younger adults appear to utilize di...

The current study examined how the deployment of spatial attention at the onset of a pointing movement influenced audiovisual crossmodal interactions at the target of the pointing action and at nontarget locations. These interactions were quantified by measuring the susceptibility to the fission (i.e., reporting two visual flashes under one flash and two auditory beep pairings) and fusion (i.e., reporting one flash under two flashes and one beep pairing) audiovisual illusions. At movement onset, unimodal, or auditory and visual bimodal stimuli were either presented at the target of the pointing action or in an adjacent, nontarget location. In Experiment 1, perceptual accuracy within the unimodal and bimodal conditions was lower in the nontarget relative to the target condition. The fission illusion was uninfluenced by target condition. However, the fusion illusion was more likely to be reported at the target relative to the nontarget location. In Experiment 2, the stimuli from Experiment 1 were further presented at a location near where the eyes were fixated (i.e., congruent condition), where the hand was aiming (i.e., target), or in a location where neither the eyes were fixated nor the hand was aiming. The results yielded the greatest susceptibility to the fusion illusion when the visual location and movement end points were congruent relative to when either movement or fixation was incongruent. Although attention may facilitate the processing of unisensory and multisensory cues in general, attention might have the strongest influence on the audiovisual integration mechanisms that underlie the sound-induced fusion illusion.

Many researchers have proposed that when an individual observes the actions of another individual, the observer simulates the action using many of the same neural areas that are involved in action production. The present study was designed to test this simulation hypothesis by comparing the perception of multisensory stimuli during both the execution and observation of an aiming action. The present work used the fusion illusion - an audio-visual illusion in which two visual stimuli presented with one auditory stimulus are erroneously perceived as being one visual stimulus. Previous research has shown that, during action execution, susceptibly to this illusion is reduced early in the execution of the movement when visual information may be more highly weighted than other sensory information. We sought to determine whether or not a non-acting observer of an action showed a similar reduction in susceptibility to the fusion illusion. Participants fixated a target and either executed or observed a manual aiming movement to that target. Audiovisual stimuli were presented at 0, 100, or 200 ms relative to movement onset and participants reported the number of perceived flashes after the movement was completed. Analysis of perceived flashes revealed that participants were less susceptible to the fusion illusion when the stimuli were presented early (100 ms) relative to later in the movement (200 ms). Critically, this pattern emerged in both execution and observation tasks. These findings support the hypothesis that observers simulate the performance of the actor and experience comparable real-time alterations in multisensory processing.

Manual handling training may be improved if it relied on the provision of individualized, augmented feedback about key movement features. The purpose of this study was to compare the reduction in sagittal spine motion during manual lifting tasks following two training approaches: didactic (DID) and augmented feedback (AUG). Untrained participants (n = 26) completed lifting tests (box, medication bag, and paramedic backboard) and a randomly-assigned intervention involving 50 practice box lifts. Lifting tests were performed immediately before and after training, and one-week after interventions. Both groups exhibited reductions in spine motions immediately and one-week after the interventions. However, the AUG intervention group elicited significantly greater reductions in 5 of 12 between-group comparisons (3 tasks × 4 spine motion variables). The results of the current study support the use of augmented feedback-based approaches to manual handling training over education-based approaches.

When moving our upper-limb towards a single target, movement times are typically shorter than when movement to a second target is required. This is known as the one-target advantage. Most studies that have demonstrated the one-target advantage have employed separate trial blocks for the one- and two-segment movements. To test if the presence of the one-target advantage depends on advance knowledge of the number of segments, the present study investigated whether the one-target advantage would emerge under different trial orders/sequences. One- and two-segment responses were organized in blocked (i.e., 1-1-1, 2-2-2), alternating (i.e., 1-2-1-2-1-2), and random (i.e., 1-1-2-1-2-2) trial sequences. Similar to previous studies, where only blocked schedules have typically been utilized, the one-target advantage emerged during the blocked and alternate conditions, but not in the random condition. This finding indicates that the one-target advantage is contingent on participants knowing the number of movement segments prior to stimulus onset.

Movement times are significantly shorter when moving from a start position to a single target, compared to when one has to continue onto a second target (i.e., the one-target advantage [OTA]). To explain this movement time difference, both the movement integration and the movement constraint hypotheses have been proposed. Although both hypotheses have been found to have explanatory power as to why the OTA exists, the support for each has been somewhat equivocal. The current review evaluated the relative support in the literature for these two hypotheses. Ultimately, preferential support for each theoretical explanation was found to be related to the higher indices of difficulty (IDs: Fitts, 1954) employed. That is, studies that included higher IDs (i.e., 6-8 bits) were more likely to provide more support for the movement constraint hypothesis, whereas studies employing lower IDs (i.e., 1-4 bits) were more likely to provide more support for the movement integration hypothesis. When the IDs employed were relatively intermediate (i.e., 5 bits), both hypotheses were mostly supported. Thus, task difficulty is crucial when determining which hypothesis better explains the planning and control of sequential goal-directed movements. Critically, the OTA most likely always involves integration but may also involve constraining if the accuracy demands are sufficiently high.

The control of ongoing goal-directed reaches is influenced by both visual and nonvisual sensorimotor processes. Notably, intentions to produce accurate movements also influence reaching performance. However, it is not known whether these improvements associated with accuracy-based intentions can be attributed to changes in movement planning and/or online control. Notably, such improvements may come about via both visual and nonvisual online control processes. Using frequency domain analyses, the relative online contributions of visual and nonvisual subprocesses to reaching performance have been previously identified (e.g., de Grosbois & Tremblay, 2018a, 2018b). Thus, the current study tested whether the relative contributions of these online control subprocesses are influenced by instructions to be accurate. Reaching movements were completed in the presence of 3 experimental manipulations. First, vision during voluntary reaches was either provided or occluded. Second, high- and low-accuracy instruction sets were provided. And third, the predictability of visual information was manipulated through blocked and randomized feedback scheduling. The results indicated that the contribution of online visuomotor processes (i.e., visual subprocess) was increased by the availability of online vision and instructions to be accurate. In contrast, the nonvisual subprocess was promoted in the absence of online vision, but suppressed when a randomized feedback schedule was implemented with instructions to be accurate. Ultimately, instructions to be accurate increase the relative contribution of vision-based online sensorimotor processes and can decrease the contributions of nonvisual online sensorimotor processes. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

When a person executes a movement, the movement is more errorful while observing another person's actions that are incongruent rather than congruent with the executed action. This effect is known as "motor contagion". Accounts of this effect are often grounded in simulation mechanisms: increased movement error emerges because the motor codes associated with observed actions compete with motor codes of the goal action. It is also possible, however, that the increased movement error is linked to eye movements that are executed simultaneously with the hand movement because oculomotor and manual-motor systems are highly interconnected. In the present study, participants performed a motor contagion task in which they executed horizontal arm movements while observing a model making either vertical (incongruent) or horizontal (congruent) movements under three conditions: no instruction, maintain central fixation, or track the model's hand with the eyes. A significant motor contagion-like effect was only found in the 'track' condition. Thus, 'motor contagion' in the present task may be an artifact of simultaneously executed incongruent eye movements. These data are discussed in the context of stimulation and associative learning theories, and raise eye movements as a critical methodological consideration for future work on motor contagion.

The utilization of visual information for the control of ongoing voluntary limb movements has been investigated for more than a century. Recently, online sensorimotor processes for the control of upper-limb reaches were hypothesized to include a distinct process related to the comparison of limb and target positions (i.e., limb-target regulation processes: Elliott et al. in Psychol Bull 136:1023–1044. doi: 10.1037/a0020958 , 2010). In the current study, this hypothesis was tested by presenting participants with brief windows of vision (20 ms) when the real-time velocity of the reaching limb rose above selected velocity criteria. One experiment tested the perceptual judgments of endpoint bias (i.e., under- vs. over-shoot), and another experiment tested the shifts in endpoint distributions following an imperceptible target jump. Both experiments revealed that limb-target regulation processes take place at an optimal velocity or “sweet spot” between movement onset and peak limb velocity (i.e., 1.0 m/s with the employed movement amplitude and duration). In contrast with pseudo-continuous models of online control (e.g., Elliott et al. in Hum Mov Sci 10:393–418. doi: 10.1016/0167-9457(91)90013-N , 1991), humans likely optimize online limb-target regulation processes by gathering visual information at a rather limited period of time, well in advance of peak limb velocity.

At rest, the central nervous system combines and integrates multisensory cues to yield an optimal percept. When engaging in action, the relative weighing of sensory modalities has been shown to be altered. Because the timing of peak velocity is the critical moment in some goal-directed movements (e.g., overarm throwing), the current study sought to test whether visual and auditory cues are optimally integrated at that specific kinematic marker when it is the critical part of the trajectory.Participants performed an upper-limb movement in which they were required to reach their peak limb velocity when the right index finger intersected a virtual target (i.e., a flinging movement). Brief auditory, visual, or audiovisual feedback (i.e., 20 ms in duration) was provided to participants at peak limb velocity. Performance was assessed primarily through the resultant position of peak limb velocity and the variability of that position.Relative to when no feedback was provided, auditory feedback significantly reduced the resultant endpoint variability of the finger position at peak limb velocity. However, no such reductions were found for the visual or audiovisual feedback conditions. Further, providing both auditory and visual cues concurrently also failed to yield the theoretically predicted improvements in endpoint variability.Overall, the central nervous system can make significant use of an auditory cue but may not optimally integrate a visual and auditory cue at peak limb velocity, when peak velocity is the critical part of the trajectory.

Rapid motor learning may occur in situations where individuals perceive a threat if they do not perform a task well. This rapid motor learning may be facilitated by improved motor performance and, consequently, more errorless practice. As a first step towards understanding the role of perceived threat on rapid motor learning, the purpose of this study was to determine how performance of a motor task is affected in situations where perceived threat is high. We hypothesized that perceived threat in a virtual environment would result in improved performance of a walking task (i.e., walking on a narrow beam). Results demonstrated that increased perceived threat did not yield statistically significantly greater balance performance in the high-threat virtual environment (median percentage of successful steps: 78.8%, 48.3%, and 55.2% in the real low-threat, virtual low-threat, and virtual high-threat environments, respectively). These results may be partially attributed to habituation to threat over time and practice. If implemented carefully, virtual reality technology can be an effective tool for investigating walking balance in environments that are perceived as threatening.

Reaches with overlapping stimulus-response spatial relations (propointing) adhere to speed–accuracy relations as defined by Paul Fitts’ index of difficulty equation (IDFitts: in bits of information). This movement principle is attributed to response mediation via the “fast” visuomotor networks of the dorsal visual pathway. It is, however, unclear whether the executive demands of dissociating stimulus-response spatial relations by reaching mirror-symmetrical to a target (antipointing) elicits similar adherence to Fitts’ equation. Here, pro- and antipointing responses were directed to a constant target amplitude with varying target widths to provide IDFitts values of 3.0, 3.5, 4.3, and 6.3 bits. Propointing movement times linearly increased with IDFitts—a result attributed to visually based trajectory corrections. In contrast, antipointing movement times, deceleration times, and endpoint precision did not adhere to Fitts’ equation. These results indicate that antipointing renders a “slow” and offline mode of control mediated by the visuoperceptual networks of the ventral visual pathway.

International audience; Prior to goal-directed actions, somatosensory target positions can be localized using either an exteroceptive or an interoceptive body representation. The goal of the present study was to investigate if the body representation selected to plan reaches to somatosensory targets is influenced by the sensory modality of the cue indicating the target's location. In the first experiment, participants reached to somatosensory targets prompted by either an auditory or a vibrotactile cue. As a baseline condition, participants also performed reaches to visual targets prompted by an auditory cue. Gaze-dependent reaching errors were measured to determine the contribution of the exteroceptive representation to motor planning processes. The results showed that reaches to both auditory-cued somatosensory targets and auditory -cued visual targets exhibited larger gaze-dependent reaching errors than reaches to vibrotactile-cued somatosensory targets. Thus, an exteroceptive body representation was likely used to plan reaches to auditory-cued somatosensory targets but not to vibrotactile-cued somatosensory targets. The second experiment examined the influence of using an exteroceptive body representation to plan movements to somatosensory targets on pre-movement neural activations. Cortical responses to a task-irrelevant visual flash were measured as participants planned movements to either auditory-cued somatosensory or auditory -cued visual targets. Larger responses (i.e., visual-evoked potentials) were found when participants planned movements to somatosensory vs. visual targets, and source analyses revealed that these activities were localized to the left occipital and left posterior parietal areas. These results suggest that visual and visuomotor processing networks were more engaged when using the exteroceptive body representation to plan movements to somato-sensory targets, than when planning movements to external visual targets.

Aims To systematically evaluate the literature on interventions that improve skills retention following advanced structured resuscitation training programs designed for healthcare professionals. Methods A systematic review of MEDLINE, EMBASE, CENTRAL, CINAHL, PsycINFO, ERIC, and Scopus was performed. Only randomized controlled trials investigating skills retention following advanced structured resuscitation training programs for healthcare professionals between inception to November 21, 2018 were included. Publications that assessed only knowledge acquisition were excluded. Relevant data from included studies were extracted and study quality was critically appraised, both independently and in duplicate by multiple reviewers. The risk of bias was assessed with the Cochrane Risk of Bias tool and the Medical Education Research Study Quality Instrument (MERSQI). Due to significant clinical heterogeneity in SRT training, study designs and interventions, a qualitative synthesis was used to summarize findings. Main results Sixteen studies, with a combined total of 1192 participants, were included in the final analysis. The majority of studies were conducted in North America and involved trainees or novice learners. ACLS was the most extensively studied, followed by NRP, ALS, and ATLS. Skills retention at 6 months was the most commonly used primary endpoint assessed using a simulated resuscitation checklist with either an adopted or created assessment tool. Most studies demonstrated a positive impact on skills retention when an interactive intervention or simulation was used. However, merely having a high-fidelity mannequin alone for simulation was found to have minimal effect on skills retention in the absence of other changes in content delivery. Booster sessions were found to be minimally effective in reinforcing long-term skills retention; however, most studies examining this intervention had small sample sizes and were underpowered. Conclusions Simulation-based interventions, refresher courses and adjustments to the content delivery of advanced structured resuscitation training courses were found to have the greatest impact on skills retention. However, due to significant heterogeneity and methodological flaws in the available studies, no definitive conclusions can be made regarding other interventions. Overall, there is a paucity of skills retention research and further high-quality randomized controlled trials are needed to determine the optimal intervention and design for resuscitation training that would maximize skills retention.

International audience; When performing upper limb reaches, the sensorimotor system can adjust to changes in target location even if the reachinglimb is not visible. To accomplish this task, sensory information about the new target location and the current position of theunseen limb are used to program online corrections. Previous researchers have argued that, prior to the initiation of corrections,somatosensory information from the unseen limb must be transformed into a visual reference frame. However, mostof these previous studies involved movements to visual targets. The purpose of the present study was to determine if visualsensorimotor transformations are also necessary for the online control of movements to somatosensory targets. Participantsperformed reaches towards somatosensory and visual targets without vision of their reaching limb. Target positions wereeither stationary, or perturbed before (~ 450 ms), or after movement onset (~ 100 ms or ~ 200 ms). In response to targetperturbations after movement onset, participants exhibited shorter correction latencies, larger correction magnitudes, andsmaller movement endpoint errors when they reached to somatosensory targets as compared to visual targets. Because referenceframe transformations have been shown to increase both processing time and errors, these results indicate that handposition was not transformed into visual reference frame during online corrections for movements to somatosensory targets.These findings support the idea that different sensorimotor transformations are used for the online control of movementsto somatosensory and visual targets.

A major challenge to the measurement of online control is the contamination by offline, planning-based processes. The current study examined the sensitivity of four measures of online control to offline changes in reaching performance induced by prism adaptation and terminal feedback. These measures included the squared Z scores (Z2) of correlations of limb position at 75% movement time versus movement end, variable error, time after peak velocity, and a frequency-domain analysis (pPower). The results indicated that variable error and time after peak velocity were sensitive to the prism adaptation. Furthermore, only the Z2 values were biased by the terminal feedback. Ultimately, the current study has demonstrated the sensitivity of limb kinematic measures to offline control processes and that pPower analyses may yield the most suitable measure of online control.

The utilization of sensory information during activities of daily living is ubiquitous both prior to and during movements (i.e., related to planning and online control, respectively). Because of the overlapping nature of online corrective processes, the quantification of feedback utilization has proven difficult. In the present study, we primarily sought to evaluate the utility of a novel analysis in the frequency domain for identifying visuomotor feedback utilization (i.e., online control). A second goal was to compare the sensitivity of the frequency analysis to that of currently utilized measures of online control. Participants completed reaching movements to targets located 27, 30, and 33 cm from a start position. During these reaches, vision of the environment was either provided or withheld. Performance was assessed across contemporary measures of online control. For the novel frequency analysis presented in this study, the acceleration profiles of reaching movements were detrended with a 5th-order polynomial fit, and the proportional power spectra were computed from the residuals of these fits. The results indicated that the use of visual feedback during reaching movements increased the contribution of the 4.68-Hz frequency to the residuals of the acceleration profiles. Comparisons across all measures of online control showed that the most sensitive measure was the squared Fisher transform of the correlation between the positions at 75 % and 100 % of the movement time. However, because such correlational measures can be contaminated by offline control processes, the frequency-domain analysis proposed herein represents a viable and promising alternative to detect changes in online feedback utilization.

Presenting target and non-target information in different modalities influences target localization if the non-target is within the spatiotemporal limits of perceptual integration. When using auditory and visual stimuli, the influence of a visual non-target on auditory target localization is greater than the reverse. It is not known, however, whether or how such perceptual effects extend to goal-directed behaviours. To gain insight into how audio-visual stimuli are integrated for motor tasks, the kinematics of reaching movements towards visual or auditory targets with or without a non-target in the other modality were examined. When present, the simultaneously presented non-target could be spatially coincident, to the left, or to the right of the target. Results revealed that auditory non-targets did not influence reaching trajectories towards a visual target, whereas visual non-targets influenced trajectories towards an auditory target. Interestingly, the biases induced by visual non-targets were present early in the trajectory and persisted until movement end. Subsequent experimentation indicated that the magnitude of the biases was equivalent whether participants performed a perceptual or motor task, whereas variability was greater for the motor versus the perceptual tasks. We propose that visually induced trajectory biases were driven by the perceived mislocation of the auditory target, which in turn affected both the movement plan and subsequent control of the movement. Such findings provide further evidence of the dominant role visual information processing plays in encoding spatial locations as well as planning and executing reaching action, even when reaching towards auditory targets.

Adam, Mol, Pratt, and Fischer (2006) reported what they termed “a violation of Fitts’s Law” – when participants aimed to targets in an array, movement times (MTs) to the last target location (highest index of difficulty (ID)) were shorter than predicted by Fitts’s Law. Based on the results of subsequent studies in which placeholders were present either during planning and/or execution stages of the movements, it was suggested that the violation may emerge because of context-dependent changes in planning processes. The present study examined this planning explanation by conducting detailed kinematic analyses of movements. Participants performed aiming movements to sets of 3 targets in different placeholder arrays with different movement amplitudes. Consistent with previous Fitts’s Law violation findings, MTs were not significantly longer for movements to the last versus middle target location. Interestingly, the pattern of peak limb velocities (typically associated with planning processes) did not mirror the changes in MTs. On the other hand, analyses of the effector’s spatial variability during the movement suggested greater involvement of online control processes when the target was in the last position. Based on these results, we suggest that the Fitts’ Law violation observed here occurred because of more efficient online control processes.

Ideomotor theory states that the neural codes that represent action and the perceptual consequences of those actions are tightly bound in a common code. For action imagination, bound action, and perceptual codes are thought to be internally activated at a sub-threshold level through action simulation. In support of this hypothesis, previous research revealed that imagined movement times (MTs) for reciprocal aiming movements were closer to actual execution MTs after the participants gained experience executing the task. The current study examined the task-specific nature of the effects of experience on imagination by determining if improvements in accuracy in the imagination of reciprocal aiming movements occur only with experience of the reciprocal aiming task or with any aiming task. To this end, one group of participants executed a reciprocal pointing task, whereas a second group executed a discrete aiming task with comparable accuracy requirements before and after imagining reciprocal aiming movements. Influence of task specificity on imagination was assessed by evaluating the changes in imagined MTs before and after execution. Consistent with previous findings, there was a reduction in imagined MTs following task execution. Critically, there was a significant time by group interaction revealing a significant pre/post reduction in imagined MTs for the group that executed the reciprocal aiming movements, but not for the group that executed the discrete aiming movements. These data support ideomotor accounts of action imagination because it appears that the imagination of a movement is affected by task-specific experience with that movement.

The authors investigated how visual information from the nondominant and dominant eyes are utilized to control ongoing dominant hand movements. Across 2 experiments, participants performed upper-limb pointing movements to a stationary target or an imperceptibly shifted target under monocular-dominant, monocular-nondominant, and binocular viewing conditions. Under monocular-dominant viewing conditions, participants exhibited better endpoint precision and accuracy. On target jump trials, participants spent more time after peak limb velocity and significantly altered their trajectories toward the new target location only when visual information from the dominant eye was available. Overall, the results suggest that the online visuomotor control processes that typically take place under binocular viewing conditions are significantly influenced by input from the dominant eye.

Visual feedback is crucial for movement accuracy (e.g., Keele and Posner, J Exp Psychol 77:155–158, 1968). As well, proprioception has been argued to be important for the control of voluntary movements (e.g., Bagesteiro et al., Exp Brain Res 171:358–370, 2006; Rossetti et al., J Neurophysiol 74:457–463, 1995). While tendon vibration (TVib) has been used to perturb proprioceptive information during limb matching tasks (Goodwin et al., Science 175:1382–1384, 1972), the current study employed between-trial dual-muscle TVib, coupled with vision occlusion, to assess the use of vision and proprioception for the online control of voluntary movements. Participants (n = 17) performed an upper-limb reaching task (30 cm). TVib influenced both accuracy and precision of movement endpoint. Critically, variability analyses showed that participant’s performance was most affected by TVib at 75% of the movement duration, even in the presence of vision. These findings demonstrate that between-trial dual-muscle tendon vibration can perturb proprioceptive feedback, and further, suggest that proprioception can be important for the online control of reaches, even when vision is available.

The commentary by Errol Hoffmann asserts that previous work by our group provides the spurious conclusion that amplitude and width manipulations to a movement environment elicit dissociable relations between movement time (MT) and P. M. Fitts' (1954) index of difficulty (ID). Hoffmann concludes that any such dissociation is the result of actions evoked entirely as ballistic. In this reply, we demonstrate that Hoffmann's commentary is a clear misrepresentation of the study goals and conclusions stated by our group. Additionally, we provide kinematic evidence that actions involving online trajectory amendments are associated with dissociable MT-ID relations for amplitude versus width manipulations. Finally, we contend that the kinematic analyses of movement trajectories, and Hoffmann's failure to acknowledge its importance, is an important step in further understanding speed-accuracy relations in human movement.

Humans can perform, perceive, and imagine voluntary movement. Numerous investigations of these abilities have employed variants of goal-directed aiming tasks because the Fitts's law equation reliably captures the mathematical relationship between movement time (MT) and accuracy requirements. The emergence of Fitts's speed-accuracy relationship during movement execution, perception, and imagination has led to the suggestion that these processes rely on common neural codes. This common coding account is based on the notion that the neural codes used to generate an action are tightly bound to the codes that represent the perceptual consequences of that action. It is suggested that during action imagination and perception the bound codes are activated offline through an action simulation. The present study provided a comprehensive testing of this common coding hypothesis by examining the characteristics of the Fitts relationship in movement execution, perception, and imagination within the same individuals. Participants were required to imagine and perceive reciprocal aiming movements with varying accuracy requirements before and after actually executing the movements. Consistent with the common coding account, the Fitts relationship was observed in all conditions. Critically, the slopes of the regression lines across tasks were not different suggesting that the core of the speed-accuracy trade-off was consistent across conditions. In addition, it was found that incidental limb position variability scaled to the amplitude of imagined movements. This motor overflow suggests motor system activation during action imagination. Overall, the results support the hypothesis that action execution, perception, and imagination rely on a common coding system.

According to action-centred models of attention, there is a tight coupling between attention and response planning processes. In support of these models, previous research has shown that reach trajectories deviate towards a cue at short (100ms) cue-target onset asynchronies (CTOAs) and away from a cue presented at longer CTOAs (750ms). These deviations resemble the pattern of facilitatory and inhibitory reaction time (RT) effects observed in keypress studies. Here, participants reached to targets following a non-predictive cue and 5 CTOAs (from 100 to 600ms in 125ms intervals) were used to gain a deeper understanding of the relationship between RT and trajectory effects. Consistent with action-centred attention, facilitatory and inhibitory cuing after-effects were present in RTs and trajectories. Interestingly, RT and trajectory effects were temporally staggered: facilitatory effects were present in trajectories at the 100ms CTOA when they had already dissipated in RTs, and inhibitory effects were present in RTs (≥350ms CTOAs) before they were detected in trajectories (600ms CTOA). The time courses of the cuing effects suggest that, although action and attention systems are tightly coupled, the facilitatory and inhibitory mechanisms operate in attention before affecting action planning.

Cheng et al. (2008) showed that when goal-directed reaching movements are performed with a 2.5 s inter-trial interval (ITI) under a randomized visual feedback schedule, individuals use online visual information on trial n to perform efficient online corrections on trial n + 1 (i.e., “reminiscence” effect). These results persisted even when participants were given knowledge of the up-coming vision condition. In this study, the ITI was extended to 5 s in an attempt to negate any effects of the preceding trial. Results from this study revealed that trials with vision were always more accurate than trials performed without vision, suggesting that individuals relied significantly on online information. Furthermore, aiming precision improved when participants knew the vision condition before each trial. It is thus suggested that the reminiscence effects are not longer evident with a 5 s ITI, which in turn allows prior knowledge of visual feedback to influence the use of online vision.

Recently, D. Elliott et al. (2010) asserted that the current control phase of a movement could be segregated in multiple processes, including impulse and limb-target regulation processes. The authors aimed to provide further empirical evidence and determine some of the constraints that govern these visuomotor processes. In 2 experiments, vision was presented or withdrawn when limb velocity was above or below selected velocity criteria. The authors observed that vision provided between 0.8 and 0.9 m/s significantly improved impulse regulation processes while vision provided up to 1.1 m/s significantly increased limb-target regulation processes. These results lend support to D. Elliott et al. and provide evidence that impulse regulation and limb-target regulation can take place at different velocities during a movement.

Elliott et al. (Hum Mov Sci 10:393–418, 1991) proposed a pseudocontinuous model of online control whereby overlapping corrections lead to the appearance of smooth kinematic profiles in the presence of online feedback. More recently, it was also proposed that online control is not a singular process [see Elliott et al. (Psychol Bull 136(6):1023–1044, 2010)]. However, support for contemporary models of online control were based on methodologies that were not designed to be sensitive to different online control sub-processes. The current study sought to evaluate the possibility of multiple distinct (i.e., visual and non-visual) mechanisms contributing to the control of reaching movements completed in either a full-vision, a no-vision, or a no-vision memory-guided condition. Frequency domain analysis was applied to the acceleration traces of reaching movements. In an attempt to elicit a modulation in the online control mechanisms, these movements were completed at two levels of spatio-temporal constraint, namely with 10 and 30 cm target distances. One finding was that performance in the full-vision relative to both no-vision conditions could be distinguished via two distinct frequency peaks. Increases in the peak magnitude at the lower frequencies were associated with visuomotor mechanisms and increases in the peak magnitude at the higher frequencies were associated with non-visual mechanisms. In addition, performance to the 30-cm target led to a lower peak at a lower frequency relative to the 10 cm target, indicating that the iterative rates of visuomotor control mechanisms are flexible and sensitive to the spatio-temporal constraints of the associated movement.

Cognitive impairment represents a significant source of disability among individuals with schizophrenia. Therefore, the aim of this study was to investigate, at a proof-of-concept level, whether one single bout of exercise can improve executive function among these individuals. In this within-participant, counterbalanced experiment, participants with schizophrenia ( n =36) completed two sessions (cycling at moderate-intensity and passively sitting) for 20 min, with a one-week washout period between the two sessions. Participants completed the Wisconsin Card Sorting Test (WCST) before and after each session to measure changes in executive function. The inclusion of both sessions completed by each participant in the analyses revealed a significant carryover effect. Consequently, only the WCST scores from the first session completed by each participant was analyzed. There was a significant time by session interaction effect for non-perseverative errors. Post-hoc Tukey's HSD contrasts revealed a significant reduction in non-perseverative errors in the exercise group that was of moderate-to-large effect. Furthermore, there was also a moderate between-group difference at post-testing. Therefore, an acute bout of exercise can improve performance on an executive function task in individuals with schizophrenia. Specifically, the reduction in non-perseverative errors on the WCST may reflect improved attention, inhibition and overall working memory.

Objective.To determine the proportion of patients with rheumatoid arthritis (RA) under rheumatologic care treated with disease-modifying antirheumatic drugs (DMARD) within 6 months from symptom onset and the components of time to treatment and its predictors.Methods.A historical inception cohort of 339 patients with RA randomly selected from 18 rheumatology practices was audited. The proportion that initiated DMARD treatment within 6 months from symptom onset was estimated using Kaplan-Meier analysis. Time to each component of the care pathway was estimated. Multivariable modeling was used to determine predictors of early treatment using 12 preselected variables available in the clinical charts. Bootstrapping was used to validate the model.Results.Within 6 months from symptom onset, 41% (95% CI 36%−46%) of patients were treated with DMARD. The median time to treatment was 8.4 (interquartile range 3.8−24) months. Events preceding rheumatology referral accounted for 78.1% of the time to treatment. The most prominent predictor of increased time to treatment was a concomitant musculoskeletal condition, such as osteoarthritis or fibromyalgia. The significance of other variables was less consistent across the models investigated. Included variables accounted for 0.69 ± 0.03 of the variability in the model.Conclusion.Fewer than 50% of patients with RA are treated with DMARD within 6 months from symptom onset. Time to referral to rheumatology represents the greatest component delay to treatment. Concomitant musculoskeletal condition was the most prominent predictor of delayed initiation of DMARD. Implications of these and other findings warrant further investigation.

This study reveals that residence time distribution (RTD) analysis with pH monitoring after acid bolus injection can be used to globally study the flow dynamics of a perfusion bioreactor, while fluorescence microscopy and magnetic resonance imaging (MRI) were used to locally investigate mass transport within a hydrogel scaffold seeded or not with cells. The bioreactor used in this study is a close-loop tubular reactor. A dispersion model in one dimension has been used to describe the non-ideal behavior of the reactor. From open-loop experiments (single-cycle analysis), the presence of stagnant zones and back mixing were observed. The impact of the flow rate, the compliance chamber volume and mixing were investigated. Intermediate flows (30, 45, 60, and 90 mL min(-1)) had no effect over RTD function expressed in reduced time (θ). Lower flow rates (5 and 15 mL min(-1)) were associated to smaller extent of dispersion. The compliance chamber volume greatly affected the dynamics of the RTD function, while the effects of mixing and flow were small to non-significant. An empirical equation has been proposed to localize minima of the RTD function and to predict Per . Finally, cells seeded in a gelatin gel at a density of 800,000 cells mL(-1) had no effect over the permeability and the apparent diffusion coefficient, as revealed by fluorescent microscopy and MRI experiments.

A trial-by-trial analysis was used to systematically examine the influence of switching visual conditions on visual feedback utilization for a manual aiming movement. In experiment one, vision was randomly manipulated from trial to trial with no more than four consecutive trials in the same visual condition. In experiment two, participants were provided with certainty of visual feedback availability prior to every trial. Results of both studies revealed that movement endpoint variability was most associated with visual feedback availability on the previous trial. Furthermore, correlation analyses comparing movement trajectory at 25, 50 and 75% with movement end (i.e. 100%) revealed that the efficiency of online corrections also depends on the availability of visual feedback on the previous trial. These results suggest that the accuracy of an aiming movement is highly dependent on processing of offline visual information from the preceding trial.

This study examined the spatial and temporal limitations of the visual corrective process in the control of upper limb movements. Real-time calculation of kinematic data was used to trigger a prismatic displacement of the movement environment during manual aiming. Using an OptoTrak motion tracking system, a data acquisition unit, and a custom-made program, perturbations were triggered at peak acceleration, peak velocity, and the estimated time of peak deceleration. Movement outcome was significantly influenced only when the visual displacement occurred at peak acceleration. The results support models of visual control that posit that early visual information is required for accurate limb control.

Metastatic spreading is a dreadful complication of neoplastic diseases that is responsible for most deaths due to cancer. It consists in the formation of secondary neoplasms from cancer cells that have detached from the primary site. The formation of these secondary sites is not random and several clinical observations indicate that the metastatic colonization exhibits organ selectivity. This organ tropism relies mostly on the complementary adhesive interactions between the cancer cells and their microenvironment. In particular, several lines of evidence suggest that the organ selectivity of colon cancer cells for the liver involves the binding of the circulating cancer cells to endothelial E-selectin. The aim of this review is to make an integrative up-date of the mechanisms that govern the organ selectivity of the metastatic process focusing more especially on the role of selectins and selectin ligands.

We examined the spatial and temporal limitations of the visual corrective process in goal-directed aiming, as well as gender differences in online control. An initial experiment was conducted to test the utility of a monocular switch procedure as a method of rapidly introducing a visual perturbation. The results revealed minimal effect of the monocular switch on movement time and the endpoint error. Following this control experiment, prismatic displacement was introduced at the initiation of and during the movement. In the third experiment, the prism was presented prior to movement initiation, and then removed at the beginning of or during the movement. Movement trajectories were most influenced by the early presentation and removal of the prism, and female performance was significantly more affected by both perturbations than male performance.

It is widely held that discrete goal-directed eye movements (saccades) are ballistic in nature because their durations are too short to allow for sensory-based online correction. Recent studies, however, have provided evidence that saccadic endpoints can be mediated via online corrections. Specifically, it has been reported that saccade trajectories adapt to the eccentricity of an unexpectedly perturbed target location (i.e., target 'jump' paradigm). If saccades are subject to online correction mechanisms, then the magnitude of such changes should scale to the amplitude of the target jump. To test this hypothesis, saccadic endpoints for trials on which the target jumped one of three amplitudes (Small: 2.5°, Medium: 5.0°, and Large: 7.5°; i.e., Jump trials) immediately after saccade onset were compared with the endpoints of trials in which the target location did not change (i.e., Reference trials). Results showed that primary saccade endpoints for Jump trials were longer than for Reference trials. Importantly, the magnitude of this increase in endpoint scaled with the amplitude of the target jump. Thus, these results support emerging and coalescent evidence that saccade trajectories are subject to online corrections.

The efficiency of online visuomotor processes was investigated by manipulating vision based on real-time upper limb velocity. Participants completed rapid reaches under two control (full vision, no vision) and three experimental visual window conditions. The experimental visual windows were early: 0.8–1.4 m/s, middle: above 1.4 m/s, and late: 1.4 to 0.8 m/s. The results indicated that endpoint consistency comparable to that of full-vision trials was observed when using vision from the early (43 ms) and middle (89 ms) windows, but vision from the middle window entailed a longer deceleration phase (i.e., a temporal cost). The late window was not useful to implement online trajectory amendments. This study provides further support for the idea of early visuomotor control, which may involve multiple online control processes during voluntary movement.

The invasive properties of cancer cells depend on their intrinsic motile potential and on their ability to breach the endothelial barrier. In the present work, we investigated the mechanisms by which adhesion of colon cancer cells to E-selectin expressed by endothelial cells regulates the barrier function of these cells and modulates transmigration of cancer cells. We found that the stimulation of E-selectin by activating antibodies or the adhesion of HT-29 cells results in an increase in the activity of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinases. In turn, the activation of p38 and ERK enhances transendothelial permeability and migration of HT-29 cells. We also obtained evidence suggesting that p38-mediated increase in transendothelial migration of cancer cells depends on a myosin light chain phosphorylation-mediated formation of stress fibres. On the other hand, the activation of ERK by E-selectin modulates the opening of interendothelial spaces by initiating the activation of Src kinase activities and the dissociation of the VE-cadherin/beta-catenin complex. We conclude that activation of E-selectin by adhering cancer cells is an important process that regulates the extravasation of colon cancer cells by initiating p38- and ERK-dependent mechanisms that both contribute to regulate the integrity of the endothelial layer.

Our objective was to improve the currently imperfect classifications of idiopathic inflammatory myopathies (IIM). In clinical practice, overlap features are common in IIM. This provided a rationale for positioning overlap clinical features at the core of a new classification system. We conducted a longitudinal study of 100 consecutive adult French Canadian patients with IIM. Clinical and laboratory data were obtained by retrospective chart review. Sera were analyzed for autoantibodies (aAbs) by protein A-assisted immunoprecipitation and double immunodiffusion. Overlap aAbs encompassed aAbs to synthetases, systemic sclerosis-associated aAbs, anti-signal recognition particle (SRP) and anti-nucleoporins. Patients were classified both at IIM diagnosis, based on data at presentation, and at the end of follow-up, based on cumulative findings. Three classifications were used: 1) the Bohan and Peter original classification, 2) a new version of that classification as modified by us, and 3) a novel clinicoserologic classification. As investigators were blinded to aAb results, the modified classification is strictly a clinical classification. Its core concept is the attribution of diagnostic significance to the presence of overlap features, that is, their presence resulted in a diagnosis of overlap myositis (OM). This approach allowed direct comparison with the original Bohan and Peter classification. By integrating aAb results to the modified classification, we also defined the clinicoserologic classification, which allowed to examine the added value of aAbs to diagnostic, therapeutic and prognostic stratification. Whereas polymyositis (PM) was the most common IIM according to the original classification, accounting for 45% of the cohort at diagnosis, its frequency fell to 14% with the modified classification. Conversely, while the frequency of myositis associated with connective tissue disease was 24% according to the original classification, the frequency of OM was 60% when using the modified classification. At last follow-up, the frequency of PM fell further to only 9%, while the frequency of OM rose to 67%. Systemic sclerosis was the most common connective tissue disease associated with IIM, accounting for 42.6% of OM patients and 29% of the cohort. The frequencies of overlap aAbs in the cohort and in OM patients were 48% and 70.5% (n =48/68), respectively. The presence of overlap aAbs at IIM diagnosis identified additional OM patients unrecognized by the modified classification. The sensitivity of the modified classification for OM at diagnosis was 87%, suggesting that clinicians may rely on the modified classification for identification of most OM patients, while awaiting results of aAb assays. The new classifications predicted the response to prednisone and IIM course. Using stringent definitions, IIM was classified as responsive or refractory after an adequate initial corticosteroid therapy, and the disease course as monophasic or chronic after a single adequate trial of prednisone. PM was always chronic and was associated with the highest rate (50%) of refractoriness to initial corticosteroid treatment. Dermatomyositis was almost always chronic (92% rate); however, its responsiveness to initial corticosteroid treatment was high (87%). OM was almost always responsive to corticosteroids (89%-100% rates). When OM patients were divided according to aAb subsets, anti-synthetase, SRP, or nucleoporin aAbs were markers for chronic myositis, whereas aAbs to U1RNP, Pm-Scl, or Ku were markers for monophasic myositis. We conclude that the original Bohan and Peter classification should be abandoned as it leads to misclassification of patients. Much of IIM is composed of OM. The proposed modified and clinicoserologic classifications have diagnostic, prognostic, and therapeutic value.

The major limitation for the application of an autologous in vitro tissue-engineered reconstructed skin (RS) for the treatment of burnt patients is the delayed vascularization of its relatively thick dermal avascular component, which may lead to graft necrosis. We have developed a human endothelialized reconstructed skin (ERS), combining keratinocytes, fibroblasts and endothelial cells (EC) in a collagen sponge. This skin substitute then spontaneously forms a network of capillary-like structures (CLS) in vitro. After transplantation to nude mice, we demonstrated that CLS containing mouse blood were observed underneath the epidermis in the ERS in less than 4 days, a delay comparable to our human skin control. In comparison, a 14-day period was necessary to achieve a similar result with the non-endothelialized RS. Furthermore, no mouse blood vessels were ever observed close to the epidermis before 14 days in the ERS and the RS. We thus concluded that the early vascularization observed in the ERS was most probably the result of inosculation of the CLS network with the host's capillaries, rather than neovascularization, which is a slower process. These results open exciting possibilities for the clinical application of many other tissue-engineered organs requiring a rapid vascularization.

A four-component aiming movement was used to examine the relative effectiveness of part and whole practice. Following a pretest, participants were assigned to one of three practice groups. Participants in a "Whole" group practiced the four components together as a unit. A "No Overlap" group practiced the first two and last two components of the task, alternating every fifth trial. An "Overlap" group practiced the transition between the second and third components on every trial by alternating practice of the first three and last three components every five trials. Participants in all groups improved significantly from pretest to immediate posttest and maintained their performance over a 24-hr delay. Contrary to the "chunking hypothesis," participants in the No Overlap group improved as much as those in the other two groups. Kinematic data indicated that participants in all three groups learned to use response-produced feedback earlier in the individual movement trajectories. Moreover, participants appeared to acquire a general ability to make transitions between movement components rather than specific transitions. The results suggest that segmented or segmented "overlap" practice regimes may benefit learning movement sequences of short duration.

The study of cerebral specialization in the Down syndrome (DS) population has revealed an anomalous pattern of organization. In particular, dichotic-listening studies have suggested a left-ear/right hemisphere dominance for speech perception, whereas motor control research has revealed a left hemisphere dominance for executive-motor control. In the present investigation, we employed a recent adaptation of the dichotic listening procedure to examine interhemispheric integration during the performance of a lateralized verbal-motor task. Specifically, using the selective dichotic-listening procedure, participants were required to complete a rapid left or right hand pointing movement to one of two pictorial icons corresponding to the word presented to their precued ear. We observed that persons with DS (N = 17) and age-matched controls (N = 35) exhibited a right-ear advantage (REA) for our dichotic-aiming task. While these results appear to contradict previous dichotic listening studies, we propose that the manifestation of a lateral ear advantage in the DS population may have more to do with the response requirements of the task than with the characteristics or complexity of the stimulus material.

Three experiments were conducted with right-handed participants to examine between-trial inhibition and facilitation effects in goal-directed aiming. Participants were required to execute rapid left-hand or right-hand aiming movements upon illumination of a target light in left or right space. Thus, from trial to trial, participants executed movements to either the same target location or a different target location with the either same hand or the other hand. Our reaction time results indicated that participants were particularly slow in initiating their movements when they were required to return to the same target location with the other hand. This was especially the case when the right hand was required to move to a target just occupied by the left hand. For both reaction time and movement time the right hand but not the left hand exhibited an advantage when it was required to perform the same movement two times in a row. Taken together these results suggest that inhibition of return, in a target-target paradigm, is more associated with the particular spatial location of the target than the organization of a specific movement to that location. Moreover, the between-trial facilitation observed for the right hand may reflect the ability of the left cerebral hemisphere to maintain an already parameterized motor program over a short intertrial interval.

We evaluated the contribution of attentional strategy to the perception of self-orientation with and without a body tilt in the median plane. Reinking et al (1974 Journal of Personality and Social Psychology30 807–811) found that the frame dependence of females on the rod-and-frame test could be mediated by instructions prompting them to focus on internal cues (ie arising from inside of the body). Here, we measured the influence of attentional instructions on the perception of the morphological horizon. Eleven females and thirteen males estimated their morphological horizon in an upright and a 45° body tilt in the median plane under three instruction conditions. All participants first performed without attentional instructions. Then, participants performed under both internal and external attentional instructions. For females, but not for males, perception of morphological horizon was more footward in the supine than in the upright orientation. Although instructions did not eliminate gender differences, internal instructions allowed females to reduce their perceptual bias in the supine orientation.