Motor Interference Research Articles

The articulatory in-out effect resists oral motor interference.

People prefer words with inward directed consonantal patterns (e.g., MENIKA) compared to outward patterns (KENIMA), because inward (outward) articulation movements resemble positive (negative) mouth actions such as swallowing (spitting). This effect might rely on covert articulation simulations, or subvocalizations, since it occurs also under silent reading. We tested to what degree these underlying articulation simulations are disturbed by oral motor interference. In 3 experiments (total N = 465) we interfered with these articulation simulations by employing concurrent oral exercises that induce oral motor noise while judging inward and outward words (chewing gum, Experiment 1; executing meaningless tongue movements, Experiment 2; concurrent verbalizations, Experiment 3). Across several word stimulus types, the articulatory in-out effect was not modulated by these tasks. This finding introduces a theoretically interesting case, because in contrast to many previous demonstrations regarding other motor-preference effects, the covert simulations in this effect are not susceptible to selective motor interference. (PsycINFO Database Record

Time-frequency analysis of event-related potentials associated with the origin of the motor interference effect from dangerous objects

Previous research has suggested that the motor interference effect of dangerous objects may originate from danger evaluations rather than direct response inhibition, as evidenced by a larger parietal P3 amplitude (which represents danger evaluations) under dangerous conditions than under safe conditions and an insignificant difference between dangerous and safe conditions in the frontal P3 component (which represents response inhibition). However, an alternative explanation exists for the null effect of the frontal P3 component. Specifically, this null effect may be attributed to cancellation between the theta and delta band oscillations, and only theta band oscillations represent response inhibition. To clarify this issue, the current study decomposed event-related potential data into different frequency bands using short-time Fourier transform. The results identified an insignificant difference of theta oscillations between dangerous and safe conditions in the mid-frontal area during a 200–500-ms time window. Instead, decreased alpha oscillations were identified in the dangerous compared with the safe condition in Go trials in the right parietal area during a 100–660-ms time window. Regression analyses further indicated that the alpha oscillations significantly contributed to the parietal P3 amplitude in the right parietal area. In summary, the results indicated that when an emergent dangerous object is encountered during the execution of prepared motor actions, an individual may tend to chiefly evaluate the potential dangerousness rather than directly suppress the prepared motor actions toward the dangerous object.

The modulation of motor control by imitating non-biological motions: a study about motor resonance.

[Purpose] Sensorimotor experience modulates motor resonance, such as motor interference, which occurs when observing others’ movements; however, it is unclear how motor resonance is modulated by intentionally imitating others’ movements. This study examined the effects of imitation experience on subsequent motor resonance. [Subjects and Methods] Twenty-seven healthy participants performed horizontal arm movements while observing non-biological, incongruent (vertical) movements of a visual stimulus (triangle object) in pre- and post-test procedures. Thirteen participants in the imitation group imitated vertical movements (non-biological motion) of the triangle object between pre- and post-test procedures and fourteen participants in the non-imitation group observed that. [Results] Variance in the executed movements was measured as an index of motor resonance. Although there was no significant difference in the non-imitation group, there was a significantly smaller variance for post-test compared to pre-test in the imitation group. [Conclusion] Motor resonance was inhibited by intentionally imitating non-biological motions. Imitating movements different from one’s own motor property might inhibit subsequent motor resonance. This finding might be applied to selectively using motor resonance as a form of rehabilitation.

Are We “Motorically” Wired to Others? High-Level Motor Computations and Their Role in Autism

High-level motor computations reflect abstract components far apart from the mere motor performance. Neural correlates of these computations have been explored both in nonhuman and human primates, supporting the idea that our brain recruits complex nodes for motor representations. Of note, these computations have exciting implications for social cognition, and they also entail important challenges in the context of autism. Here, we focus on these challenges benefiting from recent studies addressing motor interference, motor resonance, and high-level motor planning. In addition, we suggest new ideas about how one maps and shares the (motor) space with others. Taken together, these issues inspire intriguing and fascinating questions about the social tendency of our high-level motor computations, and this tendency may indicate that we are “motorically” wired to others. Thus, after furnishing preliminary insights on putative neural nodes involved in these computations, we focus on how the hypothesized social nature of high-level motor computations may be anomalous or limited in autism, and why this represents a critical challenge for the future.

Dual-task mobility among individuals with chronic stroke: changes in cognitive-motor interference patterns and relationship to difficulty level of mobility and cognitive tasks

Dual-task mobility performance is compromised after stroke. This study evaluated how the difficulty level of mobility and cognitive tasks influenced the cognitive-motor interference pattern among individuals with chronic stroke and whether it differed from age-matched control participants. A cross-sectional study. University laboratory. Individuals with chronic stroke and age-matched controls. Sixty-one individuals with chronic stroke (mean age: 62.9±7.8 years) and 32 controls (mean age: 61.0±7.3 years) performed three mobility tasks (forward walking, obstacle-crossing, backward walking) and two cognitive tasks (serial-3-subtractions, serial-7-subtractions) in single-task and dual-task conditions. time to complete the mobility tasks and correct response rates were recorded. Serial subtractions significantly increased the walking time compared to single-task walking (P<0.001) without decreasing the correct response rate (P>0.05) in both groups, indicating cognitive-related motor interference. As the difficulty of the walking task was increased (i.e., obstacle crossing), the dual-task effect on the walking time was similar to that observed during forward walking, but the correct response rate significantly decreased (P<0.05), indicating that more attentional resources were allocated to the mobility task. When the walking task difficulty level increased further (i.e., backward walking), an exaggerated increase in the walking time (P<0.001) was observed in both groups, but the stroke group also had a decreased correct response rate (P<0.001), indicative of a mutual interference pattern. The control group, however, maintained the correct response rate (P>0.05) despite the slowed walking speed in this condition (P<0.001). The degree of dual-task interference and task prioritization strategies are highly specific to the combinations of the walking and cognitive tasks used and are affected by the presence of stroke. The study results may provide the basis for establishing assessment tools and creating intervention programs that address dual-task mobility function post-stroke.

The Role of Gesture in Supporting Mental Representations: The Case of Mental Abacus Arithmetic.

People frequently gesture when problem-solving, particularly on tasks that require spatial transformation. Gesture often facilitates task performance by interacting with internal mental representations, but how this process works is not well understood. We investigated this question by exploring the case of mental abacus (MA), a technique in which users not only imagine moving beads on an abacus to compute sums, but also produce movements in gestures that accompany the calculations. Because the content of MA is transparent and readily manipulated, the task offers a unique window onto how gestures interface with mental representations. We find that the size and number of MA gestures reflect the length and difficulty of math problems. Also, by selectively interfering with aspects of gesture, we find that participants perform significantly worse on MA under motor interference, but that perceptual feedback is not critical for success on the task. We conclude that premotor processes involved in the planning of gestures are critical to mental representation in MA.

Performance of Faller and Nonfaller Older Adults on a Motor–Motor Interference Task

ABSTRACTTypically, falls in older adults occur when 2 tasks are performed simultaneously, due to the increased motor demand required to maintain stability and attention to perform the other task. The authors' purpose was to investigate walking while grasping, transporting, and placing a dowel on a predetermined target while manipulating difficulty levels of the manual task. Faller and nonfaller older adults performed a walking block (manual tasks combined with gait) and a stationary block (upright stance combined with manual tasks). The manual task involved grasping, transporting, and placing the dowel over a target. The results showed that fallers underperformed when compared with nonfallers in the task of placing the dowel over the target. The main difference observed between the groups was found in the condition that required allocation of attention between tasks and greater accuracy in the final placement of the object. Fallers showed gait stability similar to the nonfallers, but fallers were less accurate than nonfallers in the object placement task, especially for the highest level of difficulty. Thus, fallers seem to use a stability-first strategy. Fallers had problems in executing the manual tasks, which suggests a more global change in motor behavior rather than specific changes to balance control.

Response inhibition or evaluation of danger? An event-related potential study regarding the origin of the motor interference effect from dangerous objects

Previous studies have identified an interference effect from dangerous objects on prepared responses. However, its origin remains arguable. This study investigated the neural processes of this motor interference effect. The design adopted a motor priming paradigm mixed with a Go/NoGo task. Pictures of a left or right hand were used as primes, and green (Go signal) or red (NoGo signal) circles superimposed on dangerous or safe objects were used as targets. Participants were instructed to prepare the corresponding key press using the hand that was consistent with the handedness of the prime and not to execute until a Go signal appeared. Behavioral results indicated longer reaction times and a trend that participants made more errors for the dangerous condition than for the safe condition in the Go trials. However, the difference between the error rates for the dangerous and safe conditions did not emerge in the NoGo trials. Event-related potential analysis revealed a similar effect on the P3 component, which may reflect an assignment of cognitive resources to evaluate danger. More positive parietal P3 amplitudes were identified in response to the dangerous condition in the Go trials. However, the difference in the P3 amplitudes between the dangerous and safe conditions was not significant in the NoGo trials. Together, the motor interference effect from dangerous objects may originate from the danger evaluations. Furthermore, differences between the dangerous and safe conditions also emerged in the P1, posterior N1, P2, and posterior N2 components; the possible processes that underlie these components were discussed.

Sensorimotor simulation and emotion processing: Impairing facial action increases semantic retrieval demands.

Sensorimotor models suggest that understanding the emotional content of a face recruits a simulation process in which a viewer partially reproduces the facial expression in their own sensorimotor system. An important prediction of these models is that disrupting simulation should make emotion recognition more difficult. Here we used electroencephalogram (EEG) and facial electromyogram (EMG) to investigate how interfering with sensorimotor signals from the face influences the real-time processing of emotional faces. EEG and EMG were recorded as healthy adults viewed emotional faces and rated their valence. During control blocks, participants held a conjoined pair of chopsticks loosely between their lips. During interference blocks, participants held the chopsticks horizontally between their teeth and lips to generate motor noise on the lower part of the face. This noise was confirmed by EMG at the zygomaticus. Analysis of EEG indicated that faces expressing happiness or disgust-lower face expressions-elicited larger amplitude N400 when they were presented during the interference than the control blocks, suggesting interference led to greater semantic retrieval demands. The selective impact of facial motor interference on the brain response to lower face expressions supports sensorimotor models of emotion understanding.

Effect of Constrained Arm Posture on the Processing of Action Verbs.

Evidence is increasing that brain areas that are responsible for action planning and execution are activated during the information processing of action-related verbs (e.g., pick or kick). To obtain further evidence, we conducted three experiments to see if constraining arm posture, which could disturb the motor planning and imagery for that arm, would lead to delayed judgment of verbs referring to arm actions. In all experiments, native Japanese speakers judged as quickly as possible whether the presented object and the verb would be compatible (e.g., ball–throw) or not (e.g., ball–pour). Constrained arm posture was introduced to the task by asking participants to keep both hands behind their back. Two types of verbs were used: manual action verbs (i.e., verbs referring to actions performed on an object by a human hand) and non-manual action verbs. In contrast to our hypothesis that constrained arm posture would affect only the information processing of manual action verbs, the results showed delayed processing of both manual action and non-manual action verbs when the arm posture was constrained. The effect of constrained arm posture was observed even when participants responded with their voice, suggesting that the delayed judgment was not simply due to the difficulty of responding with the hand (i.e., basic motor interference). We discussed why, contrary to our hypothesis, constrained arm posture resulted in delayed CRTs regardless of the “manipulability” as symbolized by the verbs.

The effects of a single bout of exercise on motor memory interference in the trained and untrained hemisphere

Increasing evidence suggests that cardiovascular exercise has positive effects on motor memory consolidation. In this study, we investigated whether a single session of high-intensity interval training (HIIT) mitigates the effects of practicing an interfering motor task. Furthermore, learning and interference effects were assessed in the actively trained and untrained limb as it is known that unilateral motor learning can cause bilateral adaptations.Subjects performed a ballistic training and then the HIIT either before (HIIT_before) or after (HIIT_after) practicing an interfering accuracy task (AT). The control group (No_HIIT) did not participate in the HIIT but rested instead. Performance in the ballistic task (BT) was tested before and after the ballistic training, after the exercise and practice of the AT and 24h later. After ballistic training, all groups showed comparable increases in performance in the trained and untrained limb. Despite the practice of the AT, HIIT_before maintained their BT performance after the high-intensity interval training whereas HIIT_after (trend) & No_HIIT showed prominent interference effects. After 24h, HIIT_before still did not show any interference effects but further improved ballistic motor performance. HIIT_after counteracted the interference resulting in a comparable BT performance after 24h than directly after the ballistic training while No_HIIT had a significantly lower BT performance in the retention test. The results were similar in the trained and untrained limb. The current results imply that a single session of cardiovascular exercise can prevent motor interference in the trained and untrained hemisphere. Overall learning was best, and interference least, when HIIT was performed before the interfering motor task.

How can the study of action kinematics inform our understanding of human social interaction?

The kinematics of human actions are influenced by the social context in which they are performed. Motion-capture technology has allowed researchers to build up a detailed and complex picture of how action kinematics vary across different social contexts. Here we review three task domains—point-to-point imitation tasks, motor interference tasks and reach-to-grasp tasks—to critically evaluate how these tasks can inform our understanding of social interactions. First, we consider how actions within these task domains are performed in a non-social context, before highlighting how a plethora of social cues can perturb the baseline kinematics. We show that there is considerable overlap in the findings from these different tasks domains but also highlight the inconsistencies in the literature and the possible reasons for this. Specifically, we draw attention to the pitfalls of dealing with rich, kinematic data. As a way to avoid these pitfalls, we call for greater standardisation and clarity in the reporting of kinematic measures and suggest the field would benefit from a move towards more naturalistic tasks.

The influence of environmental context in interpersonal observation-execution.

Cyclical upper-limb movements involuntarily deviate from a primary movement direction when the actor concurrently observes incongruent biological motion. We examined whether environmental context influences such motor interference during interpersonal observation-execution. Participants executed continuous horizontal arm movements while observing congruent horizontal or incongruent curvilinear biological movements with or without the presence of an object positioned as an obstacle or distractor. When participants were observing a curvilinear movement, an object located within the movement space became an obstacle, and, thus, the curvilinear trajectory was essential to reach into horizontal space. When acting as a distractor, or with no object, the curvilinear trajectory was no longer essential. For observing horizontal movements, objects were located at the same relative locations as in the curvilinear movement condition. We found greater involuntary movement deviation when observing curvilinear than horizontal movements. Also, there was an influence of context only when observing horizontal movements, with greater deviation exhibited in the presence of a large obstacle. These findings suggest that the influence of environmental context is underpinned by the (mis-)matching of observed and executed actions as incongruent biological motion is primarily coded via bottom-up sensorimotor processes, whilst the congruent condition incorporates surrounding environmental features to modulate the bottom-up sensorimotor processes.

The influence of action observation on action execution: Dissociating the contribution of action on perception, perception on action, and resolving conflict.

For more than 15 years, motor interference paradigms have been used to investigate the influence of action observation on action execution. Most research on so-called automatic imitation has focused on variables that play a modulating role or investigated potential confounding factors. Interestingly, furthermore, a number of functional magnetic resonance imaging (fMRI) studies have tried to shed light on the functional mechanisms and neural correlates involved in imitation inhibition. However, these fMRI studies, presumably due to poor temporal resolution, have primarily focused on high-level processes and have neglected the potential role of low-level motor and perceptual processes. In the current EEG study, we therefore aimed to disentangle the influence of low-level perceptual and motoric mechanisms from high-level cognitive mechanisms. We focused on potential congruency differences in the visual N190 - a component related to the processing of biological motion, the Readiness Potential - a component related to motor preparation, and the high-level P3 component. Interestingly, we detected congruency effects in each of these components, suggesting that the interference effect in an automatic imitation paradigm is not only related to high-level processes such as self-other distinction but also to more low-level influences of perception on action and action on perception. Moreover, we documented relationships of the neural effects with (autistic) behavior.

51. Reference data for quantitative motor unit potential and interference pattern analysis in the genioglossus muscle

Needle electromyography (EMG) of the genioglossus muscle is a useful tool in patients with swallowing problems, that are common in many muscle and nerve diseases. Characteristic changes in motor unit potentials (MUPs) can be distinguished with MUP and interference pattern (IP) analysis. The purpose of this study was to establish reference intervals for MUP parameters using template operated multi-MUP analysis and to evaluate the IP features in the genioglossus muscle (GM) of healthy adults. We studied 28 healthy volunteers (11 men, 17 women, mean age 39 ± 12 years) with standard disposable concentric EMG needles (recording area 0.07 mm2) and an EMG system with standard settings (filters: 5 Hz–10 kHz), using an inframandibular approach. For each MUP parameter (amplitude, duration, turns) mean values and outlier limits (5th and 95th percentile) were calculated from the first 20 sampled MUPs. Data from IP plots (turns/amplitude, activity/envelope and activity/NSS) were collected in order to build normal clouds which contain >90% of the data points. MUP parameters obtained from the GM are similar to those published in literature. IP analysis is not available for healthy GM to our knowledge and could be an objective tool to quantitate the degree of abnormality in muscle and nerve diseases.

The ERP Effects of Combined Cognitive Training on Intention-Based and Stimulus-Based Actions in Older Chinese Adults

Age-related decreases in action are caused by neuromuscular weakness and cognitive decline. Although physical interventions have been reported to have beneficial effects on cognitive function in older adults, whether cognitive training improves action-related function remains unclear. In this study, we investigated the effects of combined cognitive training on intention-based and stimulus-based actions in older adults using event-related potentials (ERPs). A total of 26 healthy older adults (16 in the training group and 10 in the control group) participated in the study. The training group received 16 sessions of cognitive training, including eight sessions of executive function training and eight sessions of memory strategy training. Before and after training, both groups of participants underwent cognitive assessments and ERP recordings during both the acquisition and test phases with a motor cognitive paradigm. During the acquisition phase, subjects were asked to press one of two keys, either using a self-selected (intention-based) method or based on the preceding stimulus (stimulus-based). During the test phase, subjects were asked to respond to the pre-cues with either congruent or incongruent tasks. Using ERP indices—including readiness potential, P3 and contingent negative variation to identify motor preparation, stimulus processing and interference effect, respectively—we revealed the effects of training on both intention-based and stimulus-based actions. The correlations were also computed between the improved cognitive performance and the ERP amplitudes. It was shown that the improved executive function might extend substantial benefits to both actions, whereas associative memory may be specifically related to the bidirectional action-effect association of intention-based action, although the training effect of memory was absent during the insufficient training hours. In sum, the present study provided empirical evidence demonstrating that action could benefit from cognitive training. Clinical Trial Registration: www.chictr.org.cn, identifier: ChiCTR-OON-16007793.

The Facilitative Effect of Transcranial Direct Current Stimulation on Visuospatial Working Memory in Patients with Diabetic Polyneuropathy: A Pre-post Sham-Controlled Study.

Diabetes mellitus can lead to diabetic polyneuropathy (DPN) and cognitive deficits that manifest as peripheral and central neuropathy, respectively. In this study we investigated the relationship between visuospatial working memory (VSWM) capacity and DPN severity, and attempted to improve VSWM in DPN patients via the use of transcranial direct current stimulation (tDCS). Sixteen DPN patients and 16 age- and education-matched healthy control subjects received Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) and Montreal Cognitive Assessment (MOCA) for baseline cognitive assessment. A forward- and backward-recall computerized Corsi block tapping task (CBT), both with and without a concurrent motor interference task was used to measure VSWM capacity. Each DPN patient underwent a pre-treatment CBT, followed by tDCS or sham treatment, then a post-treatment CBT on two separate days. We found that although patients with severe DPN (Dyck’s grade 2a or 2b) showed comparable general intelligence scores on WAIS-IV as their age- and education-matched healthy counterparts, they nonetheless showed mild cognitive impairment (MCI) on MOCA and working memory deficit on digit-span test of WAIS-IV. Furthermore, patients’ peripheral nerve conduction velocity (NCV) was positively correlated with their VSWM span in the most difficult CBT condition that involved backward-recall with motor interference such that patients with worse NCV also had lower VSWM span. Most importantly, anodal tDCS over the right DLPFC was able to improve low-performing patients’ VSWM span to be on par with the high-performers, thereby eliminating the correlation between NCV and VSWM. In summary, these findings suggest that (1) MCI and severe peripheral neuropathy can coexist with unequal severity in diabetic patients, (2) the positive correlation of VSWM and NCV suggests a link between peripheral and central neuropathies, and (3) anodal tDCS over the right DLPFC can improve DPN patients’ VSWM, particularly for the low-performing patients.

Behavioral and TMS Markers of Action Observation Might Reflect Distinct Neuronal Processes.

Transcranial magnetic stimulation (TMS) studies have shown that observing an action induces muscle-specific changes in corticospinal excitability. From a signal detection theory standpoint, this pattern can be related to sensitivity, which here would measure the capacity to distinguish between two action observation conditions. In parallel to these TMS studies, action observation has also been linked to behavioral effects such as motor priming and interference. It has been hypothesized that behavioral markers of action observation could be related to TMS markers and thus represent a potentially cost-effective mean of assessing the functioning of the action-perception system. However, very few studies have looked at possible relationships between these two measures. The aim of this study was to investigate if individual differences in sensitivity to action observation could be related to the behavioral motor priming and interference effects produced by action observation. To this end, 14 healthy participants observed index and little finger movements during a TMS task and a stimulus–response compatibility task. Index muscle displayed sensitivity to action observation, and action observation resulted in significant motor priming+interference, while no significant effect was observed for the little finger in both task. Nevertheless, our results indicate that the sensitivity measured in TMS was not related to the behavioral changes measured in the stimulus–response compatibility task. Contrary to a widespread assumption, the current results indicate that individual differences in physiological and behavioral markers of action observation may be unrelated. This could have important impacts on the potential use of behavioral markers in place of more costly physiological markers of action observation in clinical settings.

Cognitive-motor interference during fine and gross motor tasks in children with Developmental Coordination Disorder (DCD)

BackgroundWhile typically developing children produce relatively automatized postural control processes, children with DCD seem to exhibit an automatization deficit. Dual tasks with various cognitive loads seem to be an effective way to assess the automatic deficit hypothesis. AimsThe aims of the study were: (1) to examine the effect of a concurrent cognitive task on fine and gross motor tasks in children with DCD, and (2) to determine whether the effect varied with different difficulty levels of the concurrent task. Methods and proceduresWe examined dual-task performance (Trail-Making-Test, Trail-Walking-Test) in 20 children with DCD and 39 typically developing children. Based on the idea of the Trail-Making-Test, participants walked along a fixed pathway, following a prescribed path, delineated by target markers of (1) increasing sequential numbers, and (2) increasing sequential numbers and letters. The motor and cognitive dual-task effects (DTE) were calculated for each task. ResultsRegardless of the cognitive task, children with DCD performed equally well in fine and gross motor tasks, and were slower in the dual task conditions than under single task-conditions, compared with children without DCD. Increased cognitive task complexity resulted in slow trail walking as well as slower trail tracing. The motor interference for the gross motor tasks was least for the simplest conditions and greatest for the complex conditions and was more pronounced in children with DCD. Cognitive interference was low irrespective of the motor task. Conclusions and implicationsChildren with DCD show a different approach to allocation of cognitive resources, and have difficulties making motor skills automatic. The latter notion is consistent with impaired cerebellar function and the “automatization deficit hypothesis”, suggesting that any deficit in the automatization process will appear if conscious monitoring of the motor skill is made more difficult by integrating another task requiring attentional resources.

Interference effects between memory systems in the acquisition of a skill.

There is now converging evidence that the declarative memory system (hippocampus dependent) contributes to sequential motor learning in concert with the procedural memory system (striatum dependent). Because of the competition for shared neuronal resources, introducing a declarative memory task can impair learning of a new motor sequence and interference may occur during the procedural consolidation process. Here, we investigated the extent to which interference effects between memory systems are seen at the retrieval phase of skill learning. Healthy participants were assigned to a control (n=15) or a declarative condition (n=15) and trained on a sequence of finger movements (FOS task). Both groups showed similar improvement at the end of the practice session on the first day. Twenty-four hours later, controls were tested solely on the FOS task, while subjects in the declarative condition first engaged in a visuospatial task. Additional offline gains in performance were observed only in the control condition. The introduction of a visuospatial memory task just before retrieval of the motor skill was sufficient to eliminate these gains. This suggests that interference between procedural and declarative memory systems may also occur during subsequent motor recall. It is proposed that the interference effects are linked, in part, to the spatial nature of the motor and declarative tasks, which specifically depends upon hippocampal involvement.