From Affordances to Abstract Words: The Flexibility of Sensorimotor Grounding

The sensorimotor system plays a critical role in several cognitive processes. Here, we review recent studies documenting this interplay at different levels. First, we concentrate on studies that have shown how the sensorimotor system is flexibly involved in interactions with objects. We report evidence demonstrating how social context and situations influence affordance activation, and then focus on tactile and kinesthetic components in body–object interactions. Then, we turn to word use, and review studies that have shown that not only concrete words, but also abstract words are grounded in the sensorimotor system. We report evidence that abstract concepts activate the mouth effector more than concrete concepts, and discuss this effect in light of studies on adults, children, and infants. Finally, we pinpoint possible sensorimotor mechanisms at play in the acquisition and use of abstract concepts. Overall, we show that the involvement of the sensorimotor system is flexibly modulated by context, and that its role can be integrated and flanked by that of other systems such as the linguistic system. We suggest that to unravel the role of the sensorimotor system in cognition, future research should fully explore the complexity of this intricate, and sometimes slippery, relation.

Rehabilitation approaches in cervical dystonia

Cervical dystonia (CD) is a form of focal muscular dystonia. The pathophysiology of CD includes central and peripheral sensorimotor mechanisms that lead to a pathological posture, imbalance, gait disturbances, and pain. Current CD treatment guidelines include botulinum toxin (BT) injections as first-line therapy. It has been established that a combination of BT injections and rehabilitation programs can reduce the disease severity, disability, and pain, improve the quality of life, and increase the duration and intensity of the BT. Even though different opinions exist on rehabilitation standards in patients with CD, several strategies are distinguished for its different types. Currently, complex kinesiotherapy for CD is being introduced, proposed by the French specialist J.P. Bleton and based on sensorimotor retraining. Other rehabilitation methods include biofeedback, transcutaneous electrical neurostimulation, and proprioceptive rehabilitation. Each of these methods has its own pathophysiological rationale in CD.

The Sensorimotor Dynamics of Joint Attention

Social interactions are composed of coordinated, multimodal behaviors with each individual taking turns and sharing attention. By the second year of life, infants are able to engage in coordinated interactions with their caregivers. Although research has focused on the social behaviors that enable parent-infant dyads to engage in joint attention, little work has been done to understand the sensorimotor mechanisms underlying coordination. Using wireless head-mounted eye trackers and motion sensing, we recorded 31 dyads as they played freely in a home-like laboratory. We identified moments of visual joint attention, when parent and infant were looking at the same object, and then measured the dyad’s head and hand movements during and around joint attention. We found evidence that both parents and infants still their bodies during joint attention. We also compared instances of joint attention that were led by the parent or by the infant and identified different sensorimotor pathways that support the two types of joint attention. These results provide the foundation for continued exploration of the critical role of sensorimotor processes on coordinated social behavior and its development.

Facial responses during listening predict authenticity judgments of vocal emotions

The ability to recognize the emotions of others is a crucial skill. In the visual modality, sensorimotor mechanisms provide an important route for emotion recognition. Perceiving facial expressions often evokes activity in facial muscles and in motor and somatosensory systems, and this activity relates to performance in emotion tasks. It remains unclear, however, whether and how similar mechanisms extend to audition. To address this issue, we examined facial electromyographic and electrodermal responses to nonverbal vocalizations that varied in emotional authenticity. Participants (N = 100) passively listened to laughs and cries that could reflect a genuine or a posed emotion. Bayesian mixed models indicated that listening to laughter evoked stronger facial responses than listening to crying. These responses were sensitive to emotional authenticity. Genuine laughs evoked more activity than posed laughs in the zygomaticus and orbicularis, muscles typically associated with positive affect. We also found that activity in the orbicularis and corrugator related to performance in a subsequent authenticity detection task. Stronger responses in the orbicularis predicted improved recognition of genuine laughs. Stronger responses in the corrugator, a muscle associated with negative affect, predicted improved recognition of posed laughs. Moreover, genuine laughs elicited stronger skin conductance responses than posed laughs. This arousal effect did not predict task performance, though. For crying, physiological responses were not associated with authenticity judgments. Altogether, these findings indicate that emotional authenticity affects peripheral nervous system responses to vocalizations. They point to a role of sensorimotor mechanisms in the evaluation of authenticity in the auditory modality.

The Human Dynamic Clamp Reveals the Fronto-Parietal Network Linking Real-Time Social Coordination and Cognition

How does the brain allow us to interact with others? Social neuroscience has already provided some answers to these questions but has tended to treat high-level, cognitive interpretations of social behavior separately from the sensorimotor mechanisms upon which they rely. The goal here is to identify the underlying neural processes and mechanisms linking sensorimotor coordination and intention attribution. We combine the human dynamic clamp, a novel paradigm for studyingrealistic social behavior, with high-resolution electroencephalography. The collection of humanness and intention attribution reports, kinematics, and neural data affords an opportunity to relate brain activity to the ongoing social behavior. Behavioral results demonstrate that sensorimotor coordination influences the judgments of cooperativeness and humanness. Analysis of brain dynamics reveals two distinct networks related to the integration of visuo-motor information from self and other which overlap over the right parietal region. Furthermore, judgment of humanness and cooperation of others modulate the functional connectivity between this right parietal hub and the prefrontal cortex. These results reveal how distributed neural dynamics integrates information from “low-level” sensorimotor mechanisms and “high-level” social cognition to support the realistic social behaviors that play out in real time during interactive scenarios.

Two Distinct Systems Represent Contralateral and Ipsilateral Sensorimotor Processes in the Human Premotor Cortex: A Dense TMS Mapping Study

Animal brains contain behaviorally committed representations of the surrounding world, which integrate sensory and motor information. In primates, sensorimotor mechanisms reside in part in the premotor cortex (PM), where sensorimotor neurons are topographically clustered according to functional specialization. Detailed functional cartography of the human PM is still under investigation. We explored the topographic distribution of spatially dependent sensorimotor functions in healthy volunteers performing left or right, hand or foot, responses to visual cues presented in the left or right hemispace, thus combining independently stimulus side, effector side, and effector type. Event-related transcranial magnetic stimulation was applied to single spots of a dense grid of 10 points on the participants’ left hemiscalp, covering the whole PM. Results showed: (1) spatially segregated hand and foot representations, (2) focal representations of contralateral cues and movements in the dorsal PM, and (3) distributed representations of ipsilateral cues and movements in the ventral and dorso-medial PM. The present novel causal information indicates that (1) the human PM is somatotopically organized and (2) the left PM contains sensory-motor representations of both hemispaces and of both hemibodies, but the hemispace and hemibody contralateral to the PM are mapped on a distinct, nonoverlapping cortical region compared to the ipsilateral ones.

The Human Dynamic Clamp reveals the fronto-parietal network linking real-time social coordination and cognition

How does the brain allow us to interact with others, and above all how does it handle situations when the goals of the interactors overlap (i.e. cooperation) or differ (i.e. competition)? Social neuroscience has already provided some answers to these questions but has tended to treat high-level, cognitive interpretations of social behavior separately from the sensorimotor mechanisms upon which they rely. The goal here is to identify the underlying neural processes and mechanisms linking sensorimotor coordination and intention attribution. We combine the Human Dynamic Clamp (HDC), a novel paradigm for studying realistic social behavior between self and other in well-controlled laboratory conditions, with high resolution electroencephalography (EEG). The collection of humanness and intention attribution reports, kinematics and neural data affords an opportunity to relate brain activity to the behavior of the HDC as well as to what the human is doing. Behavioral results demonstrate that sensorimotor coordination influences judgements of cooperativeness and humanness. Analysis of brain dynamics reveals two distinct networks related to integration of visuo-motor information from self and other. The two networks overlap over the right parietal region, an area known to be important for interpersonal motor interactions. Furthermore, connectivity analysis highlights how the judgement of humanness and cooperation of others modulate the connection between the right parietal hub and prefrontal cortex. These results reveal how distributed neural dynamics integrates information from ‘low-level’ sensorimotor mechanisms and ‘high-level’ social cognition to support the realistic social behaviors that play out in real time during interactive scenarios.Significance StatementDaily social interactions require us to coordinate with others and to reflect on their potential motives. This study investigates the brain and behavioral dynamics of these two key aspects of social cognition. Combining high-density electroencephalography and the Human Dynamic Clamp (a Virtual Partner endowed with human-based coordination dynamics), we show first, that several features of sensorimotor coordination influence attribution of intention and judgement of humanness; second, that the right parietal lobe is a key integration hub between information related to self- and other-behavior; and third, that the posterior online social hub is functionally coupled to anterior offline brain structures to support mentalizing about others. Our results stress the complementary nature of low-level and high-level mechanisms that underlie social cognition.

Affordance-based altruistic robotic architecture for human–robot collaboration

This article proposes a computational model for altruistic behavior, shows its implementation on a physical robot, and presents the results of human–robot interaction experiments conducted with the implemented system. Inspired from the sensorimotor mechanisms of the primate brain, object affordances are utilized for both intention estimation and action execution, in particular, to generate altruistic behavior. At the core of the model is the notion that sensorimotor systems developed for movement generation can be used to process the visual stimuli generated by actions of the others, infer the goals behind, and take the necessary actions to help achieving these goals, potentially leading to the emergence of altruistic behavior. Therefore, we argue that altruistic behavior is not necessarily a consequence of deliberate cognitive processing but may emerge through basic sensorimotor processes such as error minimization, that is, minimizing the difference between the observed and expected outcomes. In the model, affordances also play a key role by constraining the possible set of actions that an observed actor might be engaged in, enabling a fast and accurate intention inference. The model components are implemented on an upper-body humanoid robot. A set of experiments are conducted validating the workings of the components of the model, such as affordance extraction and task execution. Significantly, to assess how human partners interact with our altruistic model deployed robot, extensive experiments with naïve subjects are conducted. Our results indicate that the proposed computational model can explain emergent altruistic behavior in reference to its biological counterpart and moreover engage human partners to exploit this behavior when implemented on an anthropomorphic robot.