Visuo-spatial complexity potentiates the body-part effect in intransitive imitation of meaningless gestures.

Recent studies on the imitation of intransitive gestures suggest that the body part effect relies mainly upon the direct route of the dual-route model through a visuo-transformation mechanism. Here, we test the visuo-constructive hypothesis which posits that the visual complexity may directly potentiate the body part effect for meaningless gestures. We predicted that the difference between imitation of hand and finger gestures would increase with the visuo-spatial complexity of gestures. Second, we aimed to identify some of the visuo-spatial predictors of meaningless finger imitation skills. Thirty-eight participants underwent an imitation task containing three distinct set of gestures, that is, meaningful gestures, meaningless gestures with low visual complexity, and meaningless gestures with higher visual complexity than the first set of meaningless gestures. Our results were in general agreement with the visuo-constructive hypothesis, showing an increase in the difference between hand and finger gestures, but only for meaningless gestures with higher visuo-spatial complexity. Regression analyses confirm that imitation accuracy decreases with resource-demanding visuo-spatial factors. Taken together, our results suggest that the body part effect is highly dependent on the visuo-spatial characteristics of the gestures.

The Neurocognitive Bases of Meaningful Intransitive Gestures: A Systematic Review and Meta-analysis of Neuropsychological Studies.

Researchers and clinicians have long used meaningful intransitive (i.e., not tool-related; MFI) gestures to assess apraxia-a complex and frequent motor-cognitive disorder. Nevertheless, the neurocognitive bases of these gestures remain incompletely understood. Models of apraxia have assumed that meaningful intransitive gestures depend on either long-term memory (i.e., semantic memory and action lexicons) stored in the left hemisphere, or social cognition and the right hemisphere. This meta-analysis of 42 studies reports the performance of 2659 patients with either left or right hemisphere damage in tests of meaningful intransitive gestures, as compared to other gestures (i.e., MFT or meaningful transitive and MLI or meaningless intransitive) and cognitive tests. The key findings are as follows: (1) deficits of meaningful intransitive gestures are more frequent and severe after left than right hemisphere lesions, but they have been reported in both groups; (2) we found a transitivity effect in patients with lesions of the left hemisphere (i.e., meaningful transitive gestures more difficult than meaningful intransitive gestures) but a "reverse" transitivity effect in patients with lesions of the right hemisphere (i.e., meaningful transitive gestures easier than meaningful intransitive gestures); (3) there is a strong association between meaningful intransitive and transitive (but not meaningless) gestures; (4) isolated deficits of meaningful intransitive gestures are more frequent in cases with right than left hemisphere lesions; (5) these deficits may occur in the absence of language and semantic memory impairments; (6) meaningful intransitive gesture performance seems to vary according to the emotional content of gestures (i.e., body-centered gestures and emotional valence-intensity). These findings are partially consistent with the social cognition hypothesis. Methodological recommendations are given for future studies.

Knowing "what for," but not "where": Dissociation between functional and contextual tool knowledge in healthy individuals and patients with dementia.

OBJECTIVE: Semantic tool knowledge underlies the ability to perform activities of daily living. Models of apraxia have emphasized the role of functional knowledge about the action performed with tools (e.g., a hammer and a mallet allow a "hammering" action), and contextual knowledge informing individuals about where to find tools in the social space (e.g., a hammer and a mallet can be found in a workshop). The goal of this study was to test whether contextual or functional knowledge, would be central in the organization of tool knowledge. It was assumed that contextual knowledge would be more salient than functional knowledge for healthy controls and that patients with dementia would show impaired contextual knowledge. METHODS: We created an original, open-ended categorization task with ambiguity, in which the same familiar tools could be matched on either contextual or functional criteria. RESULTS: In our findings, healthy controls prioritized a contextual, over a functional criterion. Patients with dementia had normal visual categorization skills (as demonstrated by an original picture categorization task), yet they made less contextual, but more functional associations than healthy controls. CONCLUSION: The findings support a dissociation between functional knowledge ("what for") on the one hand, and contextual knowledge ("where") on the other hand. While functional knowledge may be distributed across semantic and action-related factors, contextual knowledge may actually be the name of higher-order social norms applied to tool knowledge. These findings may encourage researchers to test both functional and contextual knowledge to diagnose semantic deficits and to use open-ended categorization tests.

A fist bump in a political meeting? The influence of social context on affordance selection.

Historically, understanding human cognition such as action processing has been a challenging issue in cognitive neuropsychology and the more we know about cognition, the more we shape it as a complex, multi-determined phenomenon that is embedded in a social context. The present study aimed at understanding how the social context could influence affordance selection. We hypothesized that affordance selection would be modulated by social context and that a given hand configuration would be considered appropriate or not, as a function of the presence or absence of social context. Twenty-six healthy participants were asked to judge the appropriateness of three variants of 10 hand-object interactions based on photographs presented with or without a visual, social context. In our results, hand configurations were intrinsically acceptable or not, but this effect was modulated by the social context. A three-step model of the influence of social context on affordance selection was proposed, according to which selection depends on social norms, in the form of social knowledge and social context analysis.

Is Shadowing Behavior Caused by Body Representation Disorders and Apraxia?

Shadowing is a person-following behavior, commonly observed in dementia (e.g., Alzheimer's disease). It may be caused by neuropsychological impairments associated with posterior brain lesions, as Kudo et al. described it in a patient with posterior cortical atrophy and no frontal signs. These authors have suggested that shadowing may arise from the combination of visuospatial impairments, aphasia, apraxia, and prosopagnosia. However, how these symptoms may contribute to shadowing remains unclear. It is suggested that the combination of visuospatial impairments, body representation disorders, and apraxia, may result in complete loss of spatial representations and hence, shadowing behavior.

Grip selection without tool knowledge: end-state comfort effect in familiar and novel tool use.

A well-known phenomenon for the study of movement planning is the end-state comfort (ESC) effect: When they reach and grasp tools, individuals tend to adopt uncomfortable initial hand postures if that allows a subsequent comfortable final posture. In the context of tool use, this effect is modulated by tool orientation, task goal, and cooperation. However, the cognitive bases of the ESC effect remain unclear. The goal of this study was to determine the contribution of semantic tool knowledge and technical reasoning to movement planning, by testing whether the ESC effect typically observed with familiar tools would also be observed with novel tools. Twenty-six participants were asked to reach and grasp familiar and novel tools under varying conditions (i.e., tool's handle downward vs. upward; tool transport vs. use; solo vs. cooperation). In our findings, the effects of tool orientation, task goal and cooperation were replicated with novel tools. It follows that semantic tool knowledge is not critical for the ESC effect to occur. In fact, we found an "habitual" effect: Participant adopted uncomfortable grips with familiar tools even when it was not necessary (i.e., to transport them), probably because of the interference of habitual movement programming with actual movement programming. A cognitive view of movement planning is proposed, according to which goal comprehension (1) may rely on semantic tool knowledge, technical reasoning, and/or social skills, (2) defines end-state configuration, which in turn (3) calibrates beginning-state comfort and hence the occurrence of the ESC effect.

Sensory Integration Deficits in Neurodegenerative Diseases: Implications for Apraxia.

OBJECTIVE: Apraxia is the inability to perform voluntary, skilled movements following brain lesions, in the absence of sensory integration deficits. Yet, patients with neurodegenerative diseases (ND) may have sensory integration deficits, so we tested the associations and dissociations between apraxia and sensory integration. METHODS: A total of 44 patients with ND and 20 healthy controls underwent extensive testing of sensory integration (i.e., localization of tactile, visual, and proprioceptive stimuli; agraphesthesia; astereognosis) and apraxia (i.e., finger dexterity, imitation, tool use). RESULTS: The results showed (i) that patients with Alzheimer's disease, corticobasal syndrome, or posterior cortical atrophy were impaired on both dimensions; (ii) An association between both dimensions; (iii) that when sensory integration was controlled for, the frequency of apraxia decreased dramatically in some clinical subgroups. CONCLUSION: In a non-negligible portion of patients, the hypothesis of a disruption of sensory integration can be more parsimonious than the hypothesis of apraxia in case of impaired skilled gestures. Clinicians and researchers are advised to integrate sensory integration measures along with their evaluation of apraxia.

Involvement of the posterior tool processing network during explicit retrieval of action tool and semantic tool knowledge: an fMRI study.

Our ability to understand how to interact with familiar objects is supported by conceptual tool knowledge. Conceptual tool knowledge includes action tool and semantic tool knowledge which are supported by the ventro-dorsal and the ventral pathways, respectively. This apparent functional segregation has been recently called into question. In a block-design fMRI study, 35 participants were asked to complete manipulation, function, and association judgment tasks about pairs of familiar objects. Our results showed that lateral occipitotemporal cortex in the ventral pathway was more sensitive to manipulation and function judgment tasks compared with association judgment tasks. Functional connectivity analyses revealed distinct coupling patterns between inferior parietal lobule, lateral occipitotemporal cortex, and fusiform gyrus. Taken together, these data indicate that action tool and semantic tool knowledge are both supported by ventral and ventro-dorsal pathways. Moreover, the explicit retrieval of these representations is supported by the functional coupling of common and distinct brain regions of the posterior tool processing network varying according to the kind of relations to be retrieved.

Imitation of meaningless gestures in the Alzheimer's disease: influence of egocentric and allocentric spatial reference frames / Imitation de gestes non significatifs dans la maladie d'Alzheimer : l'influence des cadres de référence spatiale égocentrique et allocentrique

Imitation of meaningless gestures is a frequently used task to assess praxis skills in Alzheimer's disease (AD). The visuospatial analysis is considered to be one of the cognitive mechanisms most involved in perceiving the gestures of the other (i.e. model to imitate) in the imitation of meaningless gestures. However, in order to perform a classic gesture imitation task (i.e. face model), it is also necessary to transpose the representation of the other's gestures to better represent one's own gestures. This transposition can be superimposed on the dichotomy of egocentric spatial reference frames (i.e. self-gestures) and allocentric spatial reference frames (i.e. gestures of the other). Given previous researches on the relation between hippocampus and allocentric performance, we predicted that AD patients could have imitation difficulties specifically for the allocentric imitation. We thus propose a specific methodology to evaluate the imitation of meaningless gestures in both egocentric and allocentric conditions using unimanual ( i.e. one hand gestures) as well bimanual (i.e. two hand gestures) gest modalities for each condition. Our results show significant differences between the AD group and control group, except under the bimanualallocentric condition. Moreover, correlation analyses with visuospatial assessments do not validate the essential role of visuospatial abilities in our gestural imitation tasks. The comparison of the within-group results shows a significant difference between egocentric and allocentric conditions only for the elderly control group suggesting that the impact of spatial reference frames in gestural imitation would not be specific to AD. However, one should also be alert to within-pathological variability in AD, which would require a future study with several subgroups of AD patients.

L'imitation de gestes non significatifs est une tâche fréquemment utilisée pour évaluer les aptitudes praxiques de la maladie d'Alzheimer (MA). L'analyse visuospatiale est considérée comme un des mécanismes cognitifs les plus impliqués dans l'imitation de gestes non significatifs pour percevoir les gestes de l'autre (i.e., modèle à imiter). Cependant pour réaliser une tâche d'imitation de gestes en forme classique (i.e., modèle situé de face), il est également nécessaire de transposer la représentation des gestes de l'autre pour mieux se représenter ses propres gestes. Cette transposition peut être superposée à la dichotomie de l'espace égocentrique (cf. gestes de soi) et l'espace allocentrique (cf. gestes de l'autre). Nous proposons ainsi une méthodologie spécifique afin d'évaluer l'imitation de gestes à la fois en condition égocentrique et en condition allocentrique. Nos résultats montrent des différences significatives entre le groupe MA et le groupe contrôle dans toutes les conditions sauf en condition allocentrique de la modalité bimanuelle (i.e., en deux mains). De plus, les analyses de corrélation avec des évaluations visuo-spatiales ne valident pas le rôle essentiel des capacités visuo-spatiales dans nos tâches d'imitation de gestes non significatifs. La comparaison des résultats en intragroupe montrent une différence significative entre les conditions égocentrique et allocentrique uniquement pour le groupe contrôle âgé, laissant supposer que l'impact des cadres de référence spatiale dans l'imitation de gestes ne serait pas spécifique à la MA. Toutefois, il faudrait également être attentif à une variabilité intrapathologique de la MA, ce qui requerrait une future étude avec plusieurs sous-groupes des patients MA.

Meaningless imitation in neurodegenerative diseases: Effects of body part, bimanual imitation, asymmetry, and body midline crossing.

Visuo-imitative apraxia has been consistently reported in patients with dementia, yet there have been substantial methodological differences between studies, while multiple, sometimes competing hypotheses have been put forward to explain this syndrome. Our goals were to study specific imitation deficits in groups of patients who have been selected and assigned to a group solely based on clinical criteria. We tested the effects of body part, bimanual imitation, asymmetry of the model, and body midline crossing, in patients with cortical atrophy of the temporal lobes (semantic dementia, SD), frontal-parietal networks (FPN, i.e., posterior cortical atrophy and corticobasal syndrome) or both (Alzheimer's disease, AD). Sixty-three patients and 32 healthy controls were asked to imitate 45 meaningless finger/hand, uni-/bimanual, asymmetrical/symmetrical, and crossed/uncrossed postures. SD patients had subnormal imitation scores. FPN patients showed frequent and marked deficits in most conditions, better performance with hand than finger postures (probably because of visuo-constructive deficits), and better performance with uncrossed than crossed configurations (probably because of body schema disorganization). Bimanual configurations were difficult for AD patients, not because of bimanual activity in itself, but rather because of the complexity of the model. The finding of dissociations in 34/63 cases (54%) suggests that some patients, even within the same clinical category, can have variable performance in imitation tests as a function of the abovementioned factors. Clinicians are advised to use tests with a large array of items to properly capture patients' imitation skills. This provides a new basis for future research to unpack which neurocognitive mechanisms are disrupted to cause specific patterns of impaired imitation.

Semantic and action tool knowledge in the brain: Identifying common and distinct networks.

Most cognitive models of apraxia assume that impaired tool use results from a deficit occurring at the conceptual level, which contains dedicated information about tool use, namely, semantic and action tool knowledge. Semantic tool knowledge contains information about the prototypical use of familiar tools, such as function (e.g., a hammer and a mallet share the same purpose) and associative relations (e.g., a hammer goes with a nail). Action tool knowledge contains information about how to manipulate tools, such as hand posture and kinematics. The present review aimed to better understand the neural correlates of action and semantic tool knowledge, by focusing on activation, stimulation and patients' studies (left brain-damaged patients). We found that action and semantic tool knowledge rely upon a large brain network including temporal and parietal regions. Yet, while action tool knowledge calls into play the intraparietal sulcus, function relations mostly involve the anterior and posterior temporal lobe. Associative relations engaged the angular and the posterior middle temporal gyrus. Moreover, we found that hand posture and kinematics both tapped into the inferior parietal lobe and the lateral occipital temporal cortex, but no region specificity was found for one or the other representation. Our results point out the major role of both posterior middle temporal gyrus and inferior parietal lobe for action and semantic tool knowledge. They highlight the common and distinct brain networks involved in action and semantic tool networks and spur future directions on this topic.

The challenge of apraxia: Toward an operational definition?

The diagnosis of limb apraxia relies mainly on exclusion criteria (e.g., elementary motor or sensory deficits, aphasia). Due to the diversity of apraxia definitions and assessment methods, patients may or may not show apraxia depending on the chosen assessment method or theory, making the definition of apraxia somewhat arbitrary. As a result, "apraxia" may be diagnosed in patients with different cognitive impairments. Based on a quantitative and critical review of the literature, it is argued that this situation has its roots in the evolution from a task-based approach (i.e., the use of gold standard tests to detect apraxia) toward a process-based approach, namely, the deconstruction of the conceptual or production systems of action into multiple cognitive processes: language, executive functions, working memory, semantic memory, body schema, body image, visual-spatial skills, social cognition, visual-kinesthetic engrams, manipulation knowledge, technical reasoning, structural inference, and categorical apprehension. The coexistence of both approaches in the current literature is a major challenge that stands in the way of a scientific definition of apraxia. As a step toward a solution, we suggest to focus on symptoms, and on two complementary definition criteria (in addition with traditional exclusion criteria): Specificity (i.e., is apraxia explained by the alteration of cognitive processes specifically dedicated to gesture production?), and consistency (i.e., is the gesture production impairment consistent across tasks?). Two categories of limb apraxia are proposed: symptomatic apraxia (i.e., gesture production deficits that are secondary to more general cognitive impairments) and idiopathic apraxia (i.e., gesture production deficits that can be observed in isolation). It turns out that the only apraxia subtype that fulfills exclusion, specificity, and consistency criteria is limb-kinetic apraxia. A century after Liepmann's demonstration of the autonomy of apraxia toward language, the autonomy of this syndrome toward the rest of cognition remains an open question, while it poses new challenges to apraxia studies.

Physical understanding in neurodegenerative diseases.

This quantitative review gives an overview of physical understanding (i.e., the ability to represent and use the laws of physics to interact with the physical world) impairments in Alzheimer's disease (AD), semantic dementia (SD), and corticobasal syndrome (CBS), as assessed mainly with mechanical problem-solving and tool use tests. This review shows that: (1) SD patients have apraxia of tool use because of semantic tool knowledge deficits, but normal performance in tests of physical understanding; (2) AD and CBS patients show impaired performance in mechanical problem-solving tests, probably not because of intrinsic deficits of physical understanding, but rather because of additional cognitive (AD) or motor impairments (CBS); (3) As a result, the performance in mechanical problem-solving tests is not a good predictor of familiar tool use in dementia; (4) Actual deficits of physical understanding are probably observed only in late stages of neurodegenerative diseases, and associated with functional loss.

Pantomime of tool use: looking beyond apraxia.

Pantomime has a long tradition in clinical neuropsychology of apraxia. It has been much more used by researchers and clinicians to assess tool-use disorders than real tool use. Nevertheless, it remains incompletely understood and has given rise to controversies, such as the involvement of the left inferior parietal lobe or the nature of the underlying cognitive processes. The present article offers a comprehensive framework, with the aim of specifying the neural and cognitive bases of pantomime. To do so, we conducted a series of meta-analyses of brain-lesion, neuroimaging and behavioural studies about pantomime and other related tasks (i.e. real tool use, imitation of meaningless postures and semantic knowledge). The first key finding is that the area PF (Area PF complex) within the left inferior parietal lobe is crucially involved in both pantomime and real tool use as well as in the kinematics component of pantomime. The second key finding is the absence of a well-defined neural substrate for the posture component of pantomime (both grip errors and body-part-as-tool responses). The third key finding is the role played by the intraparietal sulcus in both pantomime and imitation of meaningless postures. The fourth key finding is that the left angular gyrus seems to be critical in the production of motor actions directed towards the body. The fifth key finding is that performance on pantomime is strongly correlated with the severity of semantic deficits. Taken together, these findings invite us to offer a neurocognitive model of pantomime, which provides an integrated alternative to the two hypotheses that dominate the field: The gesture-engram hypothesis and the communicative hypothesis. More specifically, this model assumes that technical reasoning (notably the left area PF), the motor-control system (notably the intraparietal sulcus), body structural description (notably the left angular gyrus), semantic knowledge (notably the polar temporal lobes) and potentially theory of mind (notably the middle prefrontal cortex) work in concert to produce pantomime. The original features of this model open new avenues for understanding the neurocognitive bases of pantomime, emphasizing that pantomime is a communicative task that nevertheless originates in specific tool-use (not motor-related) cognitive processes. .

Daily life activities in patients with Alzheimer's disease or semantic dementia: Multitasking assessment.

The aim of the present study was to compare patients with mild to moderate Alzheimer's disease (AD) or semantic dementia (SD) on their cognitive processes and the severity of their daily life activity impairments. Three types of tasks were administered to patients (SD = 15; AD = 31) and 30 healthy controls (HC): 1) informant-based scales and questionnaires, 2) a neuropsychological assessment exploring executive functions, episodic and semantic memory, and 3) a new original test featuring multi-step naturalistic actions and multitasking: the Sequential Daily Life Multitasking (SDLM). We predicted that patients with AD would mainly exhibit task perplexity, associated with episodic and executive deficits on the SDLM, while the behavior of patients with SD would mostly be characterized by object perplexity, associated with semantic memory deficits. Results showed that patients with AD or SD were impaired across all neuropsychological tests, particularly episodic memory in AD and semantic memory in SD. General performance on the SDLM also appeared dramatically impaired in both patient groups, and correlated with results of questionnaires about instrumental activities and memory impairments. However, specific qualitative measurements on the SDLM did not allow us to pinpoint different patterns of errors and behavior in patients with AD versus SD. We suggest that the inability of patients in both groups to perform the SDLM may derive from a constellation of disorders or else from more subtle impairment of cognitive and conative processes that requires further exploration.

Effect of object substitution, spontaneous compensation and repetitive training on reaching movements in a patient with optic ataxia.

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.

Imitation of meaningless gestures in normal aging.

While imitation of meaningless gestures is a gold standard in the assessment of apraxia in patients with either stroke or neurodegenerative diseases, little is known about potential age-related effects on this measure. A significant body of literature has indicated that different mechanisms (i.e., executive functioning, visuospatial skills, sensory integration, body knowledge, categorical apprehension) may underlie the performance depending on imitation conditions (i.e., finger/hand, uni-/bimanual, symmetric/asymmetric, crossed/uncrossed configurations). However, neither the effects of these conditions on performance, nor the contribution of the abovementioned mechanisms to imitation have been explored in normal aging. The aim of the present study was to fill this gap. To do so, healthy adults (n = 103) aged 50 to 89 were asked to imitate 45 meaningless gestures. The authors controlled for general cognitive function, motor function, visual-spatial skills, executive function, sensory integration, body knowledge, and mechanical problem-solving skills. The results showed that asymmetry, body-midline crossing and, to a lesser extent, bimanual activity added an additional layer of difficulty to imitation tasks. After controlling for motor speed and cognitive function, age had an effect on imitation skills after 70 years old. This may reflect a decline in body knowledge, sensory integration, and executive functions. In contrast, the visuospatial and mechanical problem-solving hypotheses were ruled out. An additional motor simulation hypothesis is proposed. These findings may prove useful for clinicians working in memory clinics by providing insights on how to interpret imitation deficits. Lower performance after 70 years old should not be considered abnormal in a systematic manner.

The - weak - role of memory in tool use: Evidence from neurodegenerative diseases.

OBJECTIVE: Although tool use disorders are frequent in neurodegenerative diseases, the question of which cognitive mechanisms are at stake is still under debate. Memory-based hypotheses (i.e., the semantic knowledge hypothesis and the manipulation knowledge hypothesis) posit that tool use relies solely on stored information about either tools or gestures whereas a reasoning-based hypothesis (i.e., the technical-semantic hypothesis) suggests that loss of semantic knowledge can be partially compensated by technical reasoning about the physical properties of tools and objects. METHOD: These three hypotheses were tested by comparing performance of 30 healthy controls, 30 patients with Alzheimer's disease and 13 patients with semantic dementia in gesture production tasks (i.e., pantomime of tool use, single tool use, real tool use) and tool or gesture recognition tasks (i.e., functional and contextual matching, recognition of tool manipulation). Individual, item-based patterns of performance were analyzed to answer the following question: Could participants demonstrate the use of tools about which they had lost knowledge? With this aim in mind, "validation" and "rebuttal" frequencies were calculated based on each prediction. RESULTS: Predictions from the technical-semantic hypothesis were more frequently observed than memory-based predictions. A number of patients were able to use and demonstrate the use of tools for which they had lost either semantic or manipulation knowledge (or both). CONCLUSIONS: These data lead to question the role of different types of memory in tool use. The hypothesis of stored, tool-specific knowledge does not predict accurately clinical performances at the individual level. This may lead to explore the influence of either additional memory systems (e.g., personal/impersonal memory) or other modes of reasoning (e.g., theory of mind) on tool use skills.