To Watch is to Work: a Review of NeuroImaging Data on Tool Use Observation Network

Organization of conceptual tool knowledge following left and right brain lesions: Evidence from neuropsychological dissociations and multivariate disconnectome symptom mapping

The aim of this work was to better understand the organization of conceptual tool knowledge following stroke. We explored specifically the link between manipulation kinematics and manipulation hand posture; and the link between manipulation kinematics and function relations in left brain-damaged (n = 30) and right brain-damaged (n = 30) patients. We examined the performance of brain-damaged patients in conceptual tool tasks using neuropsychological dissociations and disconnectome symptom mapping. Our results suggest that manipulation kinematics is more impaired than function relations, following left or right brain lesions. We also observed that manipulation kinematics and manipulation hand posture are dissociable dimensions but are still highly interrelated, particularly in left brain-damaged patients. We also found that the corpus callosum and bilateral superior longitudinal fasciculus are involved in action and semantic tool knowledge following left brain lesions. Our results provide evidence that the right hemisphere contains conceptual tool representations. Further studies are needed to better understand the mechanisms supporting the cognitive recovery of conceptual tool knowledge. An emerging hypothesis is that the right hemisphere may support functional recovery through interhemispheric transfer following a left hemisphere stroke.

The primacy of experience in language processing: Semantic priming is driven primarily by experiential similarity

The organization of semantic memory, including memory for word meanings, has long been a central question in cognitive science. Although there is general agreement that word meaning representations must make contact with sensory-motor and affective experiences in a non-arbitrary fashion, the nature of this relationship remains controversial. One prominent view proposes that word meanings are represented directly in terms of their experiential content (i.e., sensory-motor and affective representations). Opponents of this view argue that the representation of word meanings reflects primarily taxonomic structure, that is, their relationships to natural categories. In addition, the recent success of language models based on word co-occurrence (i.e., distributional) information in emulating human linguistic behavior has led to proposals that this kind of information may play an important role in the representation of lexical concepts. We used a semantic priming paradigm designed for representational similarity analysis (RSA) to quantitatively assess how well each of these theories explains the representational similarity pattern for a large set of words. Crucially, we used partial correlation RSA to account for intercorrelations between model predictions, which allowed us to assess, for the first time, the unique effect of each model. Semantic priming was driven primarily by experiential similarity between prime and target, with no evidence of an independent effect of distributional or taxonomic similarity. Furthermore, only the experiential models accounted for unique variance in priming after partialling out explicit similarity ratings. These results support experiential accounts of semantic representation and indicate that, despite their good performance at some linguistic tasks, the distributional models evaluated here do not encode the same kind of information used by the human semantic system.

Sensitivity and specificity of the action observation network to kinematics, target object, and gesture meaning

Hierarchical models have been proposed to explain how the brain encodes actions, whereby different areas represent different features, such as gesture kinematics, target object, action goal, and meaning. The visual processing of action-related information is distributed over a well-known network of brain regions spanning separate anatomical areas, attuned to specific stimulus properties, and referred to as action observation network (AON). To determine the brain organization of these features, we measured representational geometries during the observation of a large set of transitive and intransitive gestures in two independent functional magnetic resonance imaging experiments. We provided evidence for a partial dissociation between kinematics, object characteristics, and action meaning in the occipito-parietal, ventro-temporal, and lateral occipito-temporal cortex, respectively. Importantly, most of the AON showed low specificity to all the explored features, and representational spaces sharing similar information content were spread across the cortex without being anatomically adjacent. Overall, our results support the notion that the AON relies on overlapping and distributed coding and may act as a unique representational space instead of mapping features in a modular and segregated manner.

The neural correlates of limb apraxia: An anatomical likelihood estimation meta-analysis of lesion-symptom mapping studies in brain-damaged patients

Limb apraxia is a motor disorder frequently observed following a stroke. Apraxic deficits are classically assessed with four tasks: tool use, pantomime of tool use, imitation, and gesture understanding. These tasks are supported by several cognitive processes represented in a left-lateralized brain network including inferior frontal gyrus, inferior parietal lobe (IPL), and lateral occipito-temporal cortex (LOTC). For the past twenty years, voxel-wise lesion symptom mapping (VLSM) studies have been used to unravel the neural correlates associated with apraxia, but none of them has proposed a comprehensive view of the topic. In the present work, we proposed to fill this gap by performing a systematic Anatomic Likelihood Estimation meta-analysis of VLSM studies which included tasks traditionally used to assess apraxia. We found that the IPL was crucial for all the tasks. Moreover, lesions within the LOTC were more associated with imitation deficits than tool use or pantomime, confirming its important role in higher visual processing. Our results questioned traditional neurocognitive models on apraxia and may have important clinical implications.

Hemispheric asymmetry of hand and tool perception in left- and right-handers with known language dominance

Regions in the brain that are selective for images of hands and tools have been suggested to be lateralised to the left hemisphere of right-handed individuals. In left-handers, many functions related to tool use or tool pantomime may also depend more on the left hemisphere. This result seems surprising, given that the dominant hand of these individuals is controlled by the right hemisphere. One explanation is that the left hemisphere is dominant for speech and language in the majority of left-handers, suggesting a supraordinate control system for complex motor sequencing that is required for skilled tool use, as well as for speech. In the present study, we examine if this left-hemispheric specialisation extends to perception of hands and tools in left- and right-handed individuals. We, crucially, also include a group of left-handers with right-hemispheric language dominance to examine their asymmetry biases. The results suggest that tools lateralise to the left hemisphere in most right-handed individuals with left-hemispheric language dominance. Tools also lateralise to the language dominant hemisphere in right-hemispheric language dominant left-handers, but the result for left-hemispheric language dominant left-handers are more varied, and no clear bias towards one hemisphere is found. Hands did not show a group-level asymmetry pattern in any of the groups. These results suggest a more complex picture regarding hemispheric overlap of hand and tool representations, and that visual appearance of tools may be driven in part by both language dominance and the hemisphere which controls the motor-dominant hand.

Forward effects from action observation: the role of attentional focus

After viewing an image representing an action on an object, we recognize the forward states of the seen action faster than the backward states. The present study exploits a variant of a new experimental paradigm to investigate cognitive mechanisms underlying this effect. Participants viewed a series of still photos of unfolding actions on objects, each followed by a photo depicting either one of three (instead of two of the original paradigm) different and temporally distant moments after the image or one moment before the image, along with photos of different actions. Experiment 1 revealed the classical forward effects in this new context: when the task was to judge whether the action in the second photo was the same as in the first photo, evaluations were faster for all forward photos than for backward photos. In Experiment 2, we examined the role of participants' attention to the object alongside the role of attention to action kinematics in triggering these "forward effects" by manipulating participants' attentional focus. As the results showed, evaluations were faster for all forward photos when the focus was on the action kinematics, but when the focus was on the object, evaluations were faster only for the last forward photo showing the final action state. These results seem to suggest that focusing on the object triggers a representation of the action goal and thus modulates the mental simulation underlying action anticipation.

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.

fMRI evidence of movement familiarization effects on recognition memory in professional dancers

Dual-process theories propose that recognition memory involves recollection and familiarity; however, the impact of motor expertise on memory recognition, especially the interplay between familiarity and recollection, is relatively unexplored. This functional magnetic resonance imaging study used videos of a dancer performing International Latin Dance Styles as stimuli to investigate memory recognition in professional dancers and matched controls. Participants observed and then reported whether they recognized dance actions, recording the level of confidence in their recollections, whereas blood-oxygen-level-dependent signals measured encoding and recognition processes. Professional dancers showed higher accuracy and hit rates for high-confidence judgments, whereas matched controls exhibited the opposite trend for low-confidence judgments. The right putamen and precentral gyrus showed group-based moderation effects, especially for high-confidence (vs. low-confidence) action recognition in professional dancers. During action recognition, the right superior temporal gyrus and insula showed increased activation for accurate recognition and high-confidence retrieval, particularly in matched controls. These findings highlighting enhanced action memory of professional dancers-evident in their heightened recognition confidence-not only supports the dual-processing model but also underscores the crucial role of expertise-driven familiarity in bolstering successful recollection. Additionally, they emphasize the involvement of the action observation network and frontal brain regions in facilitating detailed encoding linked to intention processing.

The Primacy of Experience in Language Processing: Semantic Priming Is Driven Primarily by Experiential Similarity

The organization of semantic memory, including memory for word meanings, has long been a central question in cognitive science. Although there is general agreement that word meaning representations must make contact with sensory-motor and affective experiences in a non-arbitrary fashion, the nature of this relationship remains controversial. One prominent view proposes that word meanings are represented directly in terms of their experiential content (i.e., sensory-motor and affective representations). Opponents of this view argue that the representation of word meanings reflects primarily taxonomic structure, that is, their relationships to natural categories. In addition, the recent success of language models based on word co-occurrence (i.e., distributional) information in emulating human linguistic behavior has led to proposals that this kind of information may play an important role in the representation of lexical concepts. We used a semantic priming paradigm designed for representational similarity analysis (RSA) to quantitatively assess how well each of these theories explains the representational similarity pattern for a large set of words. Crucially, we used partial correlation RSA to account for intercorrelations between model predictions, which allowed us to assess, for the first time, the unique effect of each model. Semantic priming was driven primarily by experiential similarity between prime and target, with no evidence of an independent effect of distributional or taxonomic similarity. Furthermore, only the experiential models accounted for unique variance in priming after partialling out explicit similarity ratings. These results support experiential accounts of semantic representation and indicate that, despite their good performance at some linguistic tasks, the distributional models evaluated here do not encode the same kind of information used by the human semantic system.

On the functional brain networks involved in tool-related action understanding

Tool-use skills represent a significant cognitive leap in human evolution, playing a crucial role in the emergence of complex technologies. Yet, the neural mechanisms underlying such capabilities are still debated. Here we explore with fMRI the functional brain networks involved in tool-related action understanding. Participants viewed images depicting action-consistent (e.g., nail-hammer) and action-inconsistent (e.g., scarf-hammer) object-tool pairs, under three conditions: semantic (recognizing the tools previously seen in the pairs), mechanical (assessing the usability of the pairs), and control (looking at the pairs without explicit tasks). During the observation of the pairs, task-based left-brain functional connectivity differed within conditions. Compared to the control, both the semantic and mechanical conditions exhibited co-activations in dorsal (precuneus) and ventro-dorsal (inferior frontal gyrus) regions. However, the semantic condition recruited medial and posterior temporal areas, whereas the mechanical condition engaged inferior parietal and posterior temporal regions. Also, when distinguishing action-consistent from action-inconsistent pairs, an extensive frontotemporal neural circuit was activated. These findings support recent accounts that view tool-related action understanding as the combined product of semantic and mechanical knowledge. Furthermore, they emphasize how the left inferior parietal and anterior temporal lobes might be considered as hubs for the cross-modal integration of physical and conceptual knowledge, respectively.

Understanding the concept of a novel tool requires interaction of the dorsal and ventral streams

The left hemisphere tool-use network consists of the dorso-dorsal, ventro-dorsal, and ventral streams, each with distinct computational abilities. In the dual-loop model, the ventral pathway through the extreme capsule is associated with conceptual understanding. We performed a learning experiment with fMRI to investigate how these streams interact when confronted with novel tools. In session one, subjects observed pictures and video sequences in real world action of known and unknown tools and were asked whether they knew the tools and whether they understood their function. In session two, video sequences of unknown tools were presented again, followed again by the question of understanding their function. Different conditions were compared to each other and effective connectivity (EC) in the tool-use network was examined. During concept acquisition of an unknown tool, EC between dorsal and ventral streams was found posterior in fusiform gyrus and anterior in inferior frontal gyrus, with a functional interaction between BA44d and BA45. When previously unknown tools were presented for a second time, EC was prominent only between dorsal stream areas. Understanding the concept of a novel tool requires an interaction of the ventral stream with the dorsal streams. Once the concept is acquired, dorsal stream areas are sufficient.

A Selective Hand Posture Apraxia in an Individual With Posterior Cortical Atrophy and Probable Corticobasal Syndrome

A selective impairment for making hand postures that are required to use specific tools has rarely been reported in individuals with acquired brain injury, and such an impairment has not been documented at all in individuals with degenerative disorders. We describe an individual with posterior cortical atrophy and probable corticobasal syndrome who was unable to use tools because of an inability to make the proper hand posture required for each tool. This individual was, however, able to use the tools properly once her hand postures were corrected, and her ability to manipulate the tools (ie, timing, arm posture, and amplitude) was intact. Also, she had no difficulty with a test of her manipulation knowledge. Areas of hypoperfusion observed by single-photon emission computerized tomography included the anterior intraparietal sulcus in the left parietal lobe, which is an area that has been proposed to control hand postures. This selective impairment might be explained by the reasoning-based hypothesis for apraxia, which attributes hand posture errors in the absence of manipulation errors to dysfunction in one of the three independent pathways that subserve tool use, rather than the manipulation-based hypothesis for apraxia, which attributes hand posture errors to impaired manipulation knowledge. This is the first case with a degenerative disorder that revealed a selective impairment for making hand postures for tool use, which might be explained mainly by apraxia of hand postures along with visuospatial dysfunction (simultanagnosia) and/or sensory disturbance.

The implicit effect of action mental simulation on action evaluation

The main assumption underlying the present investigation is that action observation elicits a mandatory mental simulation representing the action forward in time. In Experiment 1, participants observed pairs of photos portraying the initial and the final still frames of an action video; then they observed a photo depicting the very same action but either forward or backward in time. Their task was to tell whether the action in the photo portrayed something happened before or after the action seen at encoding. In this explicit task, the evaluation was faster for forward photos than for backward photos. Crucially, the effect was replicated when instructions asked only to evaluate at test whether the photo depicted a scene congruent with the action seen at encoding (implicit task from two still frames, Experiment 2), and when at encoding, they were presented a single still frame and evaluated at test whether a photo depicted a scene congruent with the action seen at encoding (implicit task from single still frame; Experiment 3). Overall, the results speak in favour of a mandatory mechanism through which our brain simulates the action also in tasks that do not explicitly require action simulation.

Action Observation Network Activity Related to Object-Directed and Socially-Directed Actions in Adolescents

The human action observation network (AON) encompasses brain areas consistently engaged when we observe other's actions. Although the core nodes of the AON are present from childhood, it is not known to what extent they are sensitive to different action features during development. Because social cognitive abilities continue to mature during adolescence, the AON response to socially-oriented actions, but not to object-related actions, may differ in adolescents and adults. To test this hypothesis, we scanned with functional magnetic resonance imaging (fMRI) male and female typically-developing teenagers (n = 28; 13 females) and adults (n = 25; 14 females) while they passively watched videos of manual actions varying along two dimensions: sociality (i.e., directed toward another person or not) and transitivity (i.e., involving an object or not). We found that action observation recruited the same fronto-parietal and occipito-temporal regions in adults and adolescents. The modulation of voxel-wise activity according to the social or transitive nature of the action was similar in both groups of participants. Multivariate pattern analysis, however, revealed that decoding accuracies in intraparietal sulcus (IPS)/superior parietal lobe (SPL) for both sociality and transitivity were lower for adolescents compared with adults. In addition, in the lateral occipital temporal cortex (LOTC), generalization of decoding across the orthogonal dimension was lower for sociality only in adolescents. These findings indicate that the representation of the content of others' actions, and in particular their social dimension, in the adolescent AON is still not as robust as in adults.SIGNIFICANCE STATEMENT The activity of the action observation network (AON) in the human brain is modulated according to the purpose of the observed action, in particular the extent to which it involves interaction with an object or with another person. How this conceptual representation of actions is implemented during development is largely unknown. Here, using multivoxel pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data, we discovered that, while the action observation network is in place in adolescence, the fine-grain organization of its posterior regions is less robust than in adults to decode the abstract social dimensions of an action. This finding highlights the late maturation of social processing in the human brain.

Bringing cumulative technological culture beyond copying versus reasoning

The dominant view of cumulative technological culture suggests that high-fidelity transmission rests upon a high-fidelity copying ability, which allows individuals to reproduce the tool-use actions performed by others without needing to understand them (i.e., without causal reasoning). The opposition between copying versus reasoning is well accepted but with little supporting evidence. In this article, we investigate this distinction by examining the cognitive science literature on tool use. Evidence indicates that the ability to reproduce others' tool-use actions requires causal understanding, which questions the copying versus reasoning distinction and the cognitive reality of the so-called copying ability. We conclude that new insights might be gained by considering causal understanding as a key driver of cumulative technological culture.

A Longitudinal Relationship Between Mother's Smartphone Addiction to Child's Smartphone Addiction

Children are more likely to become addicted as they become accustomed to using smartphones, and as they observe and imitate their parents using smartphones. This study aims to confirm longitudinally the effect of mother's smartphone addiction on children's smartphone addiction. Latent growth modeling was used to analyze longitudinal relationships between 3615 pairs of children and their mothers from the Korean Children and Youth Panel Survey (KCYPS) (2018-2020). As a result, both the mothers and children's smartphone addiction significantly increased over time. The initial value of the mother's smartphone addiction was found to have a significant effect on the child's initial value and the change rate. Moreover, children's smartphone addiction change rate was significantly affected by the change rate of the mother's smartphone addiction. To intervene in children's smartphone addiction, a family-level approach, as well as parental addiction, must also be addressed, and a preventive approach should focus on those with a low risk of addiction.

The cortical thickness of the area PF of the left inferior parietal cortex mediates technical-reasoning skills

Most recent research highlights how a specific form of causal understanding, namely technical reasoning, may support the increasing complexity of tools and techniques developed by humans over generations, i.e., the cumulative technological culture (CTC). Thus, investigating the neurocognitive foundations of technical reasoning is essential to comprehend the emergence of CTC in our lineage. Whereas functional neuroimaging evidence started to highlight the critical role of the area PF of the left inferior parietal cortex (IPC) in technical reasoning, no studies explored the links between the structural characteristics of such a brain region and technical reasoning skills. Therefore, in this study, we assessed participants’ technical-reasoning performance by using two ad-hoc psycho-technical tests; then, we extracted from participants’ 3 T T1-weighted magnetic-resonance brain images the cortical thickness (i.e., a volume-related measure which is associated with cognitive performance as reflecting the size, density, and arrangement of cells in a brain region) of all the IPC regions for both hemispheres. We found that the cortical thickness of the left area PF predicts participants’ technical-reasoning performance. Crucially, we reported no correlations between technical reasoning and the other IPC regions, possibly suggesting the specificity of the left area PF in generating technical knowledge. We discuss these findings from an evolutionary perspective, by speculating about how the evolution of parietal lobes may have supported the emergence of technical reasoning in our lineage.

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.

Decoding grasp and speech signals from the cortical grasp circuit in a tetraplegic human

The cortical grasp network encodes planning and execution of grasps and processes spoken and written aspects of language. High-level cortical areas within this network are attractive implant sites for brain-machine interfaces (BMIs). While a tetraplegic patient performed grasp motor imagery and vocalized speech, neural activity was recorded from the supramarginal gyrus (SMG), ventral premotor cortex (PMv), and somatosensory cortex (S1). In SMG and PMv, five imagined grasps were well represented by firing rates of neuronal populations during visual cue presentation. During motor imagery, these grasps were significantly decodable from all brain areas. During speech production, SMG encoded both spoken grasp types and the names of five colors. Whereas PMv neurons significantly modulated their activity during grasping, SMG's neural population broadly encoded features of both motor imagery and speech. Together, these results indicate that brain signals from high-level areas of the human cortex could be used for grasping and speech BMI applications.

On the psychological origins of tool use

The ubiquity of tool use in human life has generated multiple lines of scientific and philosophical investigation to understand the development and expression of humans' engagement with tools and its relation to other dimensions of human experience. However, existing literature on tool use faces several epistemological challenges in which the same set of questions generate many different answers. At least four critical questions can be identified, which are intimately intertwined-(1) What constitutes tool use? (2) What psychological processes underlie tool use in humans and nonhuman animals? (3) Which of these psychological processes are exclusive to tool use? (4) Which psychological processes involved in tool use are exclusive to Homo sapiens? To help advance a multidisciplinary scientific understanding of tool use, six author groups representing different academic disciplines (e.g., anthropology, psychology, neuroscience) and different theoretical perspectives respond to each of these questions, and then point to the direction of future work on tool use. We find that while there are marked differences among the responses of the respective author groups to each question, there is a surprising degree of agreement about many essential concepts and questions. We believe that this interdisciplinary and intertheoretical discussion will foster a more comprehensive understanding of tool use than any one of these perspectives (or any one of these author groups) would (or could) on their own.

Technical reasoning is important for cumulative technological culture

Human technology has evolved in an unparalleled way, allowing us to expand across the globe. One fascinating question is, how do we understand the cognitive origins of this phenomenon, which is known as cumulative technological culture (CTC)? The dominant view posits that CTC results from our unique ability to learn from each other. The cultural niche hypothesis even minimizes the involvement of non-social cognitive skills in the emergence of CTC, claiming that technologies can be optimized without us understanding how they work, but simply through the retention of small improvements over generations. Here we conduct a partial replication of the experimental study of Derex et al. (Nature Human Behaviour, 2019) and show that the improvement of a physical system over generations is accompanied by an increased understanding of it. These findings indicate that technical-reasoning skills (non-social cognitive skills) are important in the acquisition, understanding and improvement of technical content-that is, specific to the technological form of cumulative culture-thereby making social learning a salient source of technical inspiration.

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. .

On the Neurocognitive Co-Evolution of Tool Behavior and Language: Insights from the Massive Redeployment Framework

Understanding the link between brain evolution and the evolution of distinctive features of modern human cognition is a fundamental challenge. A still unresolved question concerns the co-evolution of tool behavior (i.e., tool use or tool making) and language. The shared neurocognitive processes hypothesis suggests that the emergence of the combinatorial component of language skills within the frontal lobe/Broca's area made possible the complexification of tool-making skills. The importance of the frontal lobe/Broca's area in tool behavior is somewhat surprising with regard to the literature on neuropsychology and cognitive neuroscience, which has instead stressed the critical role of the left inferior parietal lobe. Therefore, to be complete, any version of the shared neurocognitive processes hypothesis needs to integrate the potential interactions between the frontal lobe/Broca's area and the left inferior parietal lobe as well as their co-evolution at a phylogenetic level. Here, we sought to provide the first elements of answer through the use of the massive deployment framework, which posits that evolutionarily older brain areas are deployed in more cognitive functions (i.e., they are less specific). We focused on the left parietal cortex, and particularly the left areas PF, PGI, and anterior intraparietal (AIP), which are known to be involved in tool use, language, and motor control, respectively. The deployment of each brain area in different cognitive functions was measured by conducting a meta-analysis of neuroimaging studies. Our results confirmed the pattern of specificity for each brain area and also showed that the left area PGI was far less specific than the left areas PF and AIP. From these findings, we discuss the different evolutionary scenarios depicting the potential co-evolution of the combinatorial and generative components of language and tool behavior in our lineage.

Improvement of Apraxia With Augmented Reality: Influencing Pantomime of Tool Use via Holographic Cues

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.

Learning versus reasoning to use tools in children

Tool behavior might be based on two strategies associated with specific cognitive mechanisms: cued-learning and technical-reasoning strategies. We aimed to explore whether these strategies coexist in young children and whether they are manifest differently through development. We presented 216 3- to 9-year-olds with a vertical maze task consisting in moving a ball from the top to the bottom of a maze. Two tool-use/mechanical actions were possible: rotating action and sliding action. Three conditions were tested, each focused on a different strategy. In the Opaque-Cue condition (cued-learning strategy), children could not see the mechanical action of each tool. Nevertheless, a cue was provided according to the tool needed to solve the problem. In the Transparent-No Cue condition (technical-reasoning strategy), no cue was presented. However, children could see the mechanical actions associated with each tool. In the Transparent-Cue condition (cued-learning and/or technical-reasoning strategies) children saw both the mechanical actions and the cues. Results indicated that the Opaque-Cue and Transparent-Cue conditions were easier than the Transparent-No-Cue condition in all children. These findings stress that children can use either cued learning or technical reasoning to use tools, according to the available information. The behavioral pattern observed in the Transparent-Cue condition suggests that children might be inclined to use technical reasoning even when the task can be solved through cued learning.

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.

Characterising factors underlying praxis deficits in chronic left hemisphere stroke patients

Limb apraxia, a disorder of skilled action not consequent on primary motor or sensory deficits, has traditionally been defined according to errors patients make on neuropsychological tasks. Previous models of the disorder have failed to provide a unified account of patients' deficits, due to heterogeneity in the patients and tasks used. In this study we hypothesised that we may be able to map apraxic deficits onto principal components, some of which may be specific, whilst others may align with other cognitive disorders. We implemented principal component analysis (PCA) to elucidate core factors of the disorder in a preliminary cohort of 41 unselected left hemisphere chronic stroke patients who were tested on a comprehensive and validated apraxia screen. Three principal components were identified: posture selection, semantic control and multi-demand sequencing. These were submitted to a lesion symptom mapping (VBCM) analysis in a subset of 24 patients, controlled for lesion volume, age and time post-stroke. The first component revealed no significant structural correlates. The second component was related to regions in inferior frontal gyrus, primary motor area, and adjacent parietal opercular (including inferior parietal and supramarginal gyrus) areas. The third component was associated with lesions within the white matter underlying the left sensorimotor cortex, likely involving the 2nd branch of the left superior longitudinal fasciculus as well as the posterior orbitofrontal cortex (pOFC). These results highlight a significant role of common cognitive functions in apraxia, which include action selection, and sequencing, whilst more specific deficits may relate to semantic control. Moreover, they suggest that previously described 'ideomotor' and 'ideational' deficits may have a common neural basis within semantic control. Further research using this technique would help elucidate the cognitive processes underlying limb apraxia, its neural correlates and their relationship with other cognitive disorders.

Hazardous tools: the emergence of reasoning in human tool use

Humans are unique in the way they understand the causal relationships between the use of tools and achieving a goal. The idea at the core of the present research is that tool use can be considered as an instance of problem-solving situations supported by technical reasoning. In an eye-tracking study, we investigated the fixation patterns of participants (N = 32) looking at 3D images of thematically consistent (e.g., nail-steel hammer) and thematically inconsistent (e.g., scarf-steel hammer) object-tool pairs that could be either "hazardous" (accidentally electrified) or not. Results showed that under thematically consistent conditions, participants focused on the tool's manipulation area (e.g., the handle of a steel hammer). However, when electrified tools were present or when the visual scene was not action-prompting, regardless of the presence of electricity, the tools' functional/identity areas (e.g., the head of a steel hammer) were fixated longer than the tools' manipulation areas. These results support an integrated and reasoning-based approach to human tool use and document, for the first time, the crucial role of mechanical/semantic knowledge in tool visual exploration.

The Pedagogue, the Engineer, and the Friend : From Whom Do We Learn?

Humans can follow different social learning strategies, sometimes oriented toward the models' characteristics (i.e., who-strategies). The goal of the present study was to explore which who-strategy is preferentially followed in the technological context based on the models' psychological characteristics. We identified three potential who-strategies: Copy the pedagogue (a model with high theory-of-mind skills), copy the engineer (a model with high technical-reasoning skills), and copy the friend (a model with high level of prosocialness). We developed a closed-group micro-society paradigm in which participants had to build the highest possible towers. Participants began with an individual building phase. Then, they were gathered to discuss the best solutions to increase tower height. After this discussion phase, they had to make a new building attempt, followed by another discussion phase, and so forth for a total of six building phases and five discussion rounds. This methodology allowed us to create an attraction score for each participant (the more an individual was copied in a group, the greater the attraction score). We also assessed participants' theory-of-mind skills, technical-reasoning skills, and prosocialness to predict participants' attraction scores based on these measures. Results show that we learn from engineers (high technical-reasoning skills) because they are the most successful. Their attraction power is not immediate, but after they have been identified as attractors, their technique is copied irrespective of their pedagogy (theory-of-mind skills) or friendliness (prosocialness). These findings open avenues for the study of the cognitive bases of human technological culture.

The elephant in the China shop: When technical reasoning meets cumulative technological culture

The commentaries have both revealed the implications of and challenged our approach. In this response, we reply to these concerns, discuss why the technical-reasoning hypothesis does not minimize the role of social-learning mechanisms - nor assume that technical-reasoning skills make individuals omniscient technically - and make suggestions for overcoming the classical opposition between the cultural versus cognitive niche hypothesis of cumulative technological culture.

Technition: When Tools Come Out of the Closet

People are ambivalently enthusiastic and anxious about how far technology can go. Therefore, understanding the neurocognitive bases of the human technical mind should be a major topic of the cognitive sciences. Surprisingly, however, scientists are not interested in this topic or address it only marginally in other mainstream domains (e.g., motor control, action observation, social cognition). In fact, this lack of interest may hinder our understanding of the necessary neurocognitive skills underlying our appetence for transforming our physical environment. Here, we develop the thesis that our technical mind originates in perhaps uniquely human neurocognitive skills, namely, technical-reasoning skills involving the area PF within the left inferior parietal lobe. This thesis creates an epistemological rupture with the state of the art that justifies the emergence of a new field in the cognitive sciences (i.e., technition) dedicated to the intelligence hidden behind tools and other forms of technologies, including constructions.

Looking to recognise: the pre-eminence of semantic over sensorimotor processing in human tool use

Alongside language and bipedal locomotion, tool use is a characterizing activity of human beings. Current theories in the field embrace two contrasting approaches: "manipulation-based" theories, which are anchored in the embodied-cognition view, explain tool use as deriving from past sensorimotor experiences, whereas "reasoning-based" theories suggest that people reason about object properties to solve everyday-life problems. Here, we present results from two eye-tracking experiments in which we manipulated the visuo-perceptual context (thematically consistent vs. inconsistent object-tool pairs) and the goal of the task (free observation or looking to recognise). We found that participants exhibited reversed tools' visual-exploration patterns, focusing on the tool's manipulation area under thematically consistent conditions and on its functional area under thematically inconsistent conditions. Crucially, looking at the tools with the aim of recognising them produced longer fixations on the tools' functional areas irrespective of thematic consistency. In addition, tools (but not objects) were recognised faster in the thematically consistent conditions. These results strongly support reasoning-based theories of tool use, as they indicate that people primarily process semantic rather than sensorimotor information to interact with the environment in an agent's consistent-with-goal way. Such a pre-eminence of semantic processing challenges the mainstream embodied-cognition view of human tool use.

The elephant in the room: What matters cognitively in cumulative technological culture

Cumulative technological culture (CTC) refers to the increase in the efficiency and complexity of tools and techniques in human populations over generations. A fascinating question is to understand the cognitive origins of this phenomenon. Because CTC is definitely a social phenomenon, most accounts have suggested a series of cognitive mechanisms oriented toward the social dimension (e.g., teaching, imitation, theory of mind, and metacognition), thereby minimizing the technical dimension and the potential influence of non-social, cognitive skills. What if we have failed to see the elephant in the room? What if social cognitive mechanisms were only catalyzing factors and not the sufficient and necessary conditions for the emergence of CTC? In this article, we offer an alternative, unified cognitive approach to this phenomenon by assuming that CTC originates in non-social cognitive skills, namely technical-reasoning skills which enable humans to develop the technical potential necessary to constantly acquire and improve technical information. This leads us to discuss how theory of mind and metacognition, in concert with technical reasoning, can help boost CTC. The cognitive approach developed here opens up promising new avenues for reinterpreting classical issues (e.g., innovation, emulation vs. imitation, social vs. asocial learning, cooperation, teaching, and overimitation) in a field that has so far been largely dominated by other disciplines, such as evolutionary biology, mathematics, anthropology, archeology, economics, and philosophy.