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Two central issues in the field of motor control are the coordinate frame in which movements are controlled and the distinction between movement planning and online correction. In this study we used these issues to frame several hypotheses about the deficits underlying ideomotor apraxia (IMA). In particular, we examined whether ideomotor apraxics e...
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... Gestures were imitated from a mirroring perspective. Participants were filmed and their imitation of each item was coded for accuracy (0 or 1) on arm posture, hand posture, amplitude, and timing components using a well-established coding system used in many prior studies (Buxbaum et al., 2005;Jax et al., 2006;Buxbaum et al., 2007;Kalénine et al., 2013;Garcea et al., 2020). Each gesture received a sum score ranging from 0 to 4 from which we calculated an overall average imitation accuracy. ...
... Imitation accuracy can be measured and defined in many different ways based on qualitative or quantitative methods, and there is no single solution for performance assessment [for a review, see (Liao et al., 2020)]. Given the variation in anatomies and kinematics between subjects that may preclude accurately quantifying imitation accuracy based on kinematics alone, we took an approach similar to the coding scheme used by Buxbaum et al. (2005). in many studies of imitation deficits in apraxia (Jax et al., 2006;Buxbaum et al., 2007;Kalénine et al., 2013;Garcea et al., 2020). This also allowed us to make more direct comparisons between our data and that of our conventional meaningless imitation task, for which the data were similarly coded. ...
... from a third-person mirroring perspective. Indeed, this measure of limb apraxia has been included in many studies, produces a robust range of scores in individuals with LCVA, correlates with other measures of apraxia, distinguishes individuals with LCVA from controls, and has neuroanatomic data to support its localization to fronto-parietal cortex (Buxbaum et al., 2005;Jax et al., 2006;Buxbaum et al., 2007;Kalénine et al., 2013;Buxbaum et al., 2014;Garcea et al., 2020). Thus, the VR task may not be sufficiently sensitive to limb apraxia. ...
Imitation is an important daily activity involved in social interactions, motor learning, and is commonly used for rehabilitation after stroke. Moreover, deficits in imitation of novel movements commonly occur after left hemisphere stroke (LCVA) in the syndrome of limb apraxia. In the current study, we used a novel virtual reality (VR) imitation paradigm to assess two factors that have remained underexplored in novel movement imitation: the imitation of complex, dynamic full-arm movements, and the effect of spatial perspective. VR holds promise as a tool for a number of clinical assessments and treatments, but has very rarely been studied in the context of imitation or diagnosis of apraxia. Thirty participants (18 with LCVA and 12 age- and education-matched controls) wore a VR headset and observed and imitated an instructor avatar demonstrating arm movements. Three spatial perspectives were examined within-subjects: first-person, third-person mirror, and third-person anatomical. Movements of the ipsilesional (left) arm were recorded and qualitatively coded for accuracy compared to the instructor avatar. Participants also completed embodiment questionnaires, a measure of limb apraxia (imitation of video-recorded meaningless movements), and three computerized background tasks that were hypothesized to evoke some of the same processing requirements of each of the three perspective conditions: a block-matching task, a block-mirroring task, and a mental rotation task. Imitation accuracy was highest in the first-person perspective, consistent with predictions, but did not differ between third-person mirror and anatomical. Surprisingly, patients and controls performed similarly on the imitation task for all spatial perspectives, with overall modest accuracy in both groups, and both patients and controls felt a moderate level of embodiment of their own avatar. Higher imitation accuracy related to quicker block-matching reaction times and higher mental rotation accuracy, regardless of perspective, but was unrelated to imitation of video-recorded meaningless movements. In sum, virtual reality provides advantages in terms of experimental manipulation and control but may present challenges in detecting clinical imitation deficits (limb apraxia).
... Repetition can bias future movements to resemble recently repeated ones [1], a phenomenon referred to as use-dependent learning (UDL). The effects of UDL can be seen in features such as the direction and speed of the current movement, and has been observed in movements ranging from single-joint actions to whole-body locomotion [2][3][4][5][6][7][8][9][10]. Theoretically, these movement biases have been attributed to shifts in the tuning of neurons towards the direction of a frequently practiced movement, a form of plasticity that alters the sensorimotor map underlying movement execution [11][12][13][14][15]. ...
Repetition of specific movement biases subsequent actions towards the practiced movement, a phenomenon known as use-dependent learning (UDL). Recent experiments that impose strict constraints on planning time have revealed two sources of use-dependent biases, one arising from dynamic changes occurring during motor planning and another reflecting a stable shift in motor execution. Here, we used a distributional analysis to examine the contribution of these biases in reaching. To create the conditions for UDL, the target appeared at a designated ‘frequent’ location on most trials, and at one of six ‘rare’ locations on other trials. Strikingly, the heading angles were bimodally distributed, with peaks at both frequent and rare target locations. Despite having no constraints on planning time, participants exhibited a robust bias towards the frequent target when movements were self-initiated quickly, the signature of a planning bias; notably, the peak near the rare target was shifted in the frequently practiced direction, the signature of an execution bias. Furthermore, these execution biases were not only replicated in a delayed-response task but were also insensitive to reward. Taken together, these results extend our understanding of how volitional movements are influenced by recent experience.
... SMG is often implicated in tasks that tap into the knowledge for actions, and lesions to this region and pMTG lead to ideomotor apraxia (Buxbaum, Kyle, & Menon, 2005;Haaland, Harrington, & Knight, 2000;Jax, Buxbaum, & Moll, 2006;Tranel, Kemmerer, Adolphs, H. Damasio, & A. Damasio, 2003). Consistent with this region's role in the praxis features of object knowledge (e.g., Buxbaum, Kyle, Tang, & Detre, 2006), repetitive TMS to left SMG in a picture naming task selectively impairs the naming of manipulable artifacts (Pobric, Jefferies, & Lambon Ralph, 2010). ...
Traditionally, psycholinguistic models and models of speech motor control have approached the word production process from different angles and have remained, to a large extent, separate from one another. Ultimately, however, the process entails the entire pathway from semantic processing to articulation: producing a word from meaning requires activating a concept, retrieving the word, selecting its segments, ordering those segments into the right sequence, and finally articulating them with the correct timing. This chapter reviews the neural basis of word production from the complementary perspectives of the psycholinguistic literature and the speech motor control literature.
... aIPL has a well-established role in tool use, action planning, and goal-oriented action execution from numerous neuroimaging and lesion studies (Binkofski et al., 2016;Buxbaum et al., 2007;Jax et al., 2006;Peeters et al., 2013;Randerath et al., 2017;Vingerhoets, 2014) in addition to action semantics in single-word studies (e.g., Kuhnke et al., 2020). It is the central node in a tool use network formed by structural connections to posterior middle temporal and inferior frontal regions (Ramayya et al., 2010). ...
... Similarly during action execution, they suggested that aIPS is associated with planning the grasp, and aSMG with planning the tool movement to achieve a goal. Ideomotor apraxia is often the result of damage to aIPL (Haaland et al., 2000;Jax et al., 2006). It results in impairments in imitating actions and gestures, pantomiming, recognizing object-related pantomimes, and planning object-related actions (Buxbaum et al., 2005;Goldenberg & Karnath, 2006;Varney & Damasio, 1987). ...
Abstract concepts can potentially be represented using metaphorical mappings to concrete domains. This view predicts that when linguistic metaphors are processed, they will invoke sensory-motor simulations. Here, I examine evidence from neuroimaging and lesion studies that addresses whether metaphors in language are embodied in this manner. Given the controversy in this area, I first outline some criteria by which the quality of neuroimaging and lesion studies might be evaluated. I then review studies of metaphors in various sensory-motor domains, such as action, motion, texture, taste, and time, and examine their strengths and weaknesses. Studies of idioms are evaluated next. I also address some neuroimaging studies that can speak to the question of metaphoric conceptual organization without explicit use of linguistic metaphors. I conclude that the weight of the evidence suggests that metaphors are indeed grounded in sensory-motor systems. The case of idioms is less clear, and I suggest that they might be grounded in a qualitatively different manner than metaphors at higher levels of the action hierarchy. While metaphors are unlikely to explain all aspects of abstract concept representation, for some specific abstract concepts, there is also nonlinguistic neural evidence for metaphoric conceptual organization.
... Imitation impairments in these patients also dissociate from deficits in the ability to recognize gestures, suggesting that imitation deficits are not due to more general cognitive impairments (Mozaz, 1992). Our work as well as that of others has revealed that patients with apraxia are overly reliant on visual feedback to guide their movements (Howard et al., 2019;Jax et al., 2006;Mutha et al., 2010;Okita et al., 2017). Depriving patients of visual feedback through blindfolding, for example, results in significantly worse imitation performance for apraxic versus non-apraxic individuals (Jax et al., 2006). ...
... Our work as well as that of others has revealed that patients with apraxia are overly reliant on visual feedback to guide their movements (Howard et al., 2019;Jax et al., 2006;Mutha et al., 2010;Okita et al., 2017). Depriving patients of visual feedback through blindfolding, for example, results in significantly worse imitation performance for apraxic versus non-apraxic individuals (Jax et al., 2006). Blindfolding also reduces the number of error-correction attempts made by individuals with apraxia, as well as the success of those attempts (Howard et al., 2019). ...
... Note that testing a truly visual-only imitation task would have required blocking or disrupting proprioceptive feedback of the limb in some way. Here we simply provide cursor-only feedback that includes no information about the desired arm configuration; previous research suggests that neurotypical individuals and (to an even greater degree) patients with left hemisphere stroke rely primarily on visual feedback when it is available (Bagesteiro et al., 2005;Block & Bastian, 2010;Howard et al., 2019;Jax et al., 2006;Mutha et al., 2010;Okita et al., 2017;Over, 1966). Hence our two conditions likely biased individuals to imitate using the sensory modality in which they were cued. ...
The ability to imitate observed actions serves as an efficient method for learning novel movements and is specifically impaired (without concomitant gross motor impairments) in the neurological disorder of limb apraxia, a disorder common after left hemisphere stroke. Research with apraxic patients has advanced our understanding of how people imitate. However, the role of proprioception in imitation has been rarely assessed directly. Prior work has proposed that proprioceptively sensed body position is transformed into a visual format, supporting the attainment of a desired imitation goal represented visually (i.e., how the movement should look when performed). In contrast, we hypothesized a more direct role for proprioception: we suggest that movement goals are also represented proprioceptively (i.e., how a desired movement should feel when performed), and the ability to represent or access such proprioceptive goals is deficient in apraxia. Using a novel imitation task in which a robot cued meaningless trajectories proprioceptively or visually, we probed the role of each sensory modality. We found that patients with left hemisphere stroke were disproportionately worse than controls at imitating when cued proprioceptively versus visually. This proprioceptive versus visual disparity was associated with apraxia severity as assessed by a traditional imitation task, but could not be explained by general proprioceptive impairment or speed-accuracy trade-offs. These data suggest that successful imitation depends in part on the ability to represent movement goals in terms of how those movements should feel, and that deficits in this ability contribute to imitation impairments in patients with apraxia.
... Contextual information may provide critical cues facilitating the access to an adequate motor concept and may constrain the possibilities for action production (15)(16)(17). While tactile feedback alone, such as a stick that resembles the handle of a tool, seems to be inefficient in evoking the correct motor program of an action (20,21), several studies underlined the role of visual feedback (11,17,22). In this regard, it has been shown that the perception of object affordances (i.e., action possibilities offered by the environment and the object's properties) and its visual attributes is influenced by its visuo-perceptual context, such as thematic and functional properties but also by space (23). ...
... The realness and high spatial presence evoked by our holograms may have made pantomiming less symbolic as it was rather influenced by the strong external cues. Further, it has been shown that apraxics have deficits in intrinsic coordinate control (11,22). In such, participants might have extrinsically coordinated their movements in reference to the dynamic or holographic objects. ...
... Another likely explanation for the improvements is that both the dynamic and holographic information provided error signals for the perceptual-motor system as suggested by Jax et al. (11). While patients with apraxia often struggle in movement preparation (i.e., planning) the adjustment of the movement plan (i.e., online correction) is often intact (22). Similar to reports of Jax and colleagues (11) about the observed "conduit d'approche" in some patients, we also noted an increase in accuracy after multiple repetitions. ...
Background: Defective pantomime of tool use is a hall mark of limb apraxia. Contextual information has been demonstrated to improve tool use performance. Further, knowledge about the potential impact of technological aids such as augmented reality for patients with limb apraxia is still scarce.
Objective: Since augmented reality offers a new way to provide contextual information, we applied it to pantomime of tool use. We hypothesize that the disturbed movement execution can be mitigated by holographic stimulation. If visual stimuli facilitate the access to the appropriate motor program in patients with apraxia, their performance should improve with increased saliency, i.e., should be better when supported by dynamic and holographic cues vs. static and screen-based cues.
Methods: Twenty one stroke patients and 23 healthy control subjects were randomized to mime the use of five objects, presented in two Environments (Screen vs. Head Mounted Display, HMD) and two Modes (Static vs. Dynamic) resulting in four conditions (ScreenStat, ScreenDyn, HMDStat, HMDDyn), followed by a real tool demonstration. Pantomiming was analyzed by a scoring system using video recordings. Additionally, the sense of presence was assessed using a questionnaire.
Results: Healthy control participants performed close to ceiling and significantly better than patients. Patients achieved significantly higher scores with holographic or dynamic cues. Remarkably, when their performance was supported by animated holographic cues (e.g., striking hammer), it did not differ significantly from real tool demonstration. As the sense of presence increases with animated holograms, so does the pantomiming.
Conclusion: Patients' performance improved with visual stimuli of increasing saliency. Future assistive technology could be implemented upon this knowledge and thus, positively impact the rehabilitation process and a patient's autonomy.
... Imitation impairments in these patients also dissociate from deficits in the ability to recognize gestures, suggesting that imitation deficits are not due to more general cognitive impairments (Mozaz, 1992). Our work as well as that of others has revealed that patients with apraxia are overly reliant on visual feedback to guide their movements (Howard et al., 2019;Jax et al., 2006;Mutha et al., 2010;Okita et al., 2017). Depriving patients of visual feedback through blindfolding, for example, results in significantly worse imitation performance for apraxic versus non-apraxic individuals (Jax et al., 2006). ...
... Our work as well as that of others has revealed that patients with apraxia are overly reliant on visual feedback to guide their movements (Howard et al., 2019;Jax et al., 2006;Mutha et al., 2010;Okita et al., 2017). Depriving patients of visual feedback through blindfolding, for example, results in significantly worse imitation performance for apraxic versus non-apraxic individuals (Jax et al., 2006). Blindfolding also reduces the number of error-correction attempts made by individuals with apraxia, as well as the success of those attempts (Howard et al., 2019). ...
... /2021 limb apraxia. Unlike neurotypical controls, these patients are particularly impaired at imitating and in correcting their errors when blindfolded (Howard et al., 2019;Jax et al., 2006), suggesting that they are overly reliant on visual versus proprioceptive feedback when imitating. Here, we observed that in comparison to neurotypical controls, patients with left hemisphere stroke are indeed particularly impaired when asked to imitate movements that are cued purely proprioceptively. ...
The ability to imitate observed actions serves as an efficient method for learning novel movements and is specifically impaired (without concomitant gross motor impairments) in the neurological disorder of limb apraxia, a disorder common after left hemisphere stroke. Research with apraxic patients has advanced our understanding of how people imitate. However, the role of proprioception in imitation has been rarely assessed directly. Prior work has proposed that proprioceptively sensed body position is transformed into a visual format, supporting the attainment of a desired imitation goal represented visually (i.e., how the movement should look when performed). In contrast, we hypothesized a more direct role for proprioception: we suggest that movement goals are also represented proprioceptively (i.e., how a desired movement should feel when performed), and the ability to represent or access such proprioceptive goals is deficient in apraxia. Using a novel imitation task in which a robot cued meaningless trajectories purely proprioceptively or visually, we separately probed the role of each sensory modality. We found that patients with left hemisphere stroke were disproportionately worse than controls at imitating when cued proprioceptively versus visually. The proprioceptive versus visual disparity was associated with apraxia severity as assessed by a traditional imitation task, but could not be explained by general proprioceptive impairment or speed-accuracy trade-offs. These data suggest that successful imitation depends in part on the ability to represent movement goals in terms of how those movements should feel, and that deficits in this ability contribute to imitation impairments in patients with apraxia.
... Damasio et al. (2001) demonstrated involvement of the aIPL when comparing the naming of actions performed with an implement with the naming of actions performed without an implement. Ideomotor apraxia, a condition characterized by damage to the aIPL/IPL, typically leads to impairments in skilled motor performance, problems in gesture imitation and difficulty in initiating the appropriate action in response to an object (Heilman et al., 1982;Heilman and Rothi, 1993;Haaland et al., 2000;Jax et al., 2006). ...
Studies on the organization of conceptual knowledge have examined categories of concrete nouns extensively. Less is known about the neural basis of verb categories suggested by linguistic theories. We used functional MRI to examine the differences between manner verbs, which encode information about the manner of an action, versus instrument verbs, which encode information about an object as part of their meaning. Using both visual and verbal stimuli and a combination of univariate and multivariate pattern analyses, our results show that accessing conceptual representations of instrument class involves brain regions typically associated with complex action and object perception, including the anterior inferior parietal cortex and occipito-temporal cortex. On the other hand, accessing conceptual representations of the manner class involves regions that are commonly associated with the processing of visual and biological motion, in the posterior superior temporal sulcus. These findings support the idea that the semantics of manner and instrument verbs are supported by distinct neural mechanisms.
... The SMG, especially anteriorly, is considered part of the somatosensory association cortex, implicated in storing proprioceptive information for complex motor sequences, planning and performing skilled actions, and reaching and grasping. Lesions to the anterior SMG have been associated with action knowledge impairment, apraxia, and impairments in tool use (Buxbaum & Saffran, 2002;Buxbaum, Veramontil, & Schwartz, 2000;Goldenberg & Spatt, 2009;Haaland, Harrington, & Knight, 2000;Jax, Buxbaum, & Moll, 2006;Randerath, Goldenberg, Spijkers, Li, & Hermsd€ orfer, 2010;Tranel, Damasio, & Damasio, 1997;Tranel et al., 2003). Imaging studies implicate anterior SMG and surrounding anterior inferior parietal cortex with complex actions (Brandi, Wohlschlager, Sorg, & Hermsdorfer, 2014;Frey, Vinton, Norlund, & Grafton, 2005;Hermsdorfer, Terlinden, Muhlau, Goldenberg, & Wohlschlager, 2007;Johnson-Frey, Newman- Norlund, & Grafton, 2005;Peeters et al., 2009) and action semantics ( Binder et al., 2009;Desai, Binder, Conant, & Seidenberg, 2010;Desai, Choi, Lai, & Henderson, 2016;Desai et al., 2013;Kable et al., 2005;Noppeney, Price, Penny, & Friston, 2006;Rueschemeyer, van Rooij, Lindemann, Willems, & Bekkering, 2010). ...
The neural bases of action and abstract concept representations remain a topic of debate. While several lines of research provide evidence for grounding of action-related conceptual content into sensory-motor systems, results of traditional lesion-deficit studies have been somewhat inconsistent. Further, few studies have directly compared the neural substrates of action and relatively abstract verb comprehension post-stroke. Here, we investigated the impact of the disruption of two neural networks on comprehension of action and relatively abstract verbs in 48 unilateral left-hemisphere stroke patients using two methodologies: 1) lesion-deficit association and 2) resting-state functional connectivity (RSFC) analyses. Disruption of RSFC between the left inferior frontal gyrus and right hemisphere primary and secondary sensory-motor areas predicted greater relative impairment of action semantics. Voxel-based lesion-symptom mapping revealed that damage to frontal white matter, extending towards the inferior frontal gyrus, also predicted greater relative impairment of action semantics. On the other hand, damage to the left anterior middle temporal gyrus significantly impaired the more abstract category relative to action. These findings support the view that action and non-action/abstract semantic processing rely on partially dissociable brain networks, with action concepts relying more heavily on sensory-motor areas. The results also have wider implications for lesion-deficit association studies and show how the contralateral hemisphere can play a compensatory role following unilateral stroke.
... That being said, the grasping component is in an intermediate position between reaching and using in that it can be viewed as a high-level perceptual-motor skill (Rosenbaum, Chapman, Weigelt, Weiss, & Van der Wel, 2012). Indeed, grasping may depend not only on structural information (i.e., the shape or size of the object; Ellis & Tucker, 2000) but also on functional information (i.e., knowledge about the function and the prototypical manipulation of an object; Buxbaum, Kyle, Tang, & Detre, 2006;Jax, Buxbaum, & Moll, 2006) and intentional/teleological information (i.e., the action to be done with the object; Osiurak et al., 2008;Rosenbaum et al., 2012). Function-based grasping may depend on the left inferior parietal lobe whereas structure-based grasping is associated with the left superior parietal lobe (Buxbaum, Sirigu, Schwartz, & Klatzky, 2003). ...
We report the case of M.B. who demonstrated severe optic ataxia with the right hand following stroke in the left hemisphere. The clinical picture may shed light on both the pathological characteristics of reaching and grasping actions, and potential rehabilitation strategies for optic ataxia. First, M.B. demonstrated a dissociation between severely impaired reaching and relatively spared grasping and tool use skills and knowledge, which confirms that grasping may be more intermingled with non-motoric cognitive mechanisms than reaching. Besides, M.B.’s reaching performance was sensitive to movement repetition. We observed a substitution effect: Reaching time decreased if M.B. repeatedly reached toward the same object but increased when object identity changed. This may imply that not only object localization but also object identity, is integrated into movement programming in reach-to-grasp tasks. Second, studying M.B.’s spontaneous compensation strategies ascertained that the mere repetition of reaching movements had a positive effect, to the point M.B. almost recovered to normal level after an intensive one-day repetitive training session. This case study seems to provide one of the first examples of optic ataxia rehabilitation. Reaching skills can be trained by repetitive training even two years post-stroke and despite the presence of visuo-imitative apraxia.
