Contribution of motor representations to action verb processing

Imagining and reading actions: Towards similar motor representations

While action language and motor imagery both engage the motor system, determining whether these two processes indeed share the same motor representations would contribute to better understanding their underlying mechanisms. We conducted two experiments probing the mutual influence of these two processes. In Exp.1, hand-action verbs were presented subliminally, and participants (n = 36) selected the verb they thought they perceived from two alternatives. When congruent actions were imagined prior to this task, accuracy significantly increased, i.e. participants were better able to "see" the subliminal verbs. In Exp.2, participants (n = 19) imagined hand flexion or extension, while corticospinal excitability was measured via transcranial magnetic stimulation. Corticospinal excitability was modulated by action verbs subliminally presented prior to imagery. Specifically, the typical increase observed during imagery was suppressed after presentation of incongruent action verbs. This mutual influence of action language and motor imagery, both at behavioral and neurophysiological levels, suggests overlapping motor representations.

Does the Motor Cortex Want the Full Story? The Influence of Sentence Context on Corticospinal Excitability in Action Language Processing

The reading of action verbs has been shown to activate motor areas, whereby sentence context may serve to either globally strengthen this activation or to selectively sharpen it. To investigate this issue, we manipulated the presence of manual actions and sentence context, assessing the level of corticospinal excitability by means of transcranial magnetic stimulation. We hypothesized that context would serve to sharpen the neural representation of the described actions in the motor cortex, reflected in context-specific modulation of corticospinal excitability. Participants silently read manual action verbs and non-manual verbs, preceded by a full sentence (rich context) or not (minimal context). Transcranial magnetic stimulation pulses were delivered at rest or shortly after verb presentation. The coil was positioned over the cortical representation of the right first dorsal interosseous (pointer finger). We observed a general increase of corticospinal excitability while reading both manual action and non-manual verbs in minimal context, whereas the modulation was action-specific in rich context: corticospinal excitability increased while reading manual verbs, but did not differ from baseline for non-manual verbs. These findings suggest that sentence context sharpens motor representations, activating the motor cortex when relevant and eliminating any residual motor activation when no action is present.

Kinesthetic motor-imagery training improves performance on lexical-semantic access

The objective of this study was to evaluate the effect of Motor Imagery (MI) training on language comprehension. In line with literature suggesting an intimate relationship between the language and the motor system, we proposed that a MI-training could improve language comprehension by facilitating lexico-semantic access. In two experiments, participants were assigned to a kinesthetic motor-imagery training (KMI) group, in which they had to imagine making upper-limb movements, or to a static visual imagery training (SVI) group, in which they had to mentally visualize pictures of landscapes. Differential impacts of both training protocols on two different language comprehension tasks (i.e., semantic categorization and sentence-picture matching task) were investigated. Experiment 1 showed that KMI training can induce better performance (shorter reaction times) than SVI training for the two language comprehension tasks, thus suggesting that a KMI-based motor activation can facilitate lexico-semantic access after only one training session. Experiment 2 aimed at replicating these results using a pre/post-training language assessment and a longer training period (four training sessions spread over four days). Although the improvement magnitude between pre- and post-training sessions was greater in the KMI group than in the SVI one on the semantic categorization task, the sentence-picture matching task tended to provide an opposite pattern of results. Overall, this series of experiments highlights for the first time that motor imagery can contribute to the improvement of lexical-semantic processing and could open new avenues on rehabilitation methods for language deficits.

How humor is experienced: An embodied metaphor account

The study explores the humor-body association from the perspective of embodied cognition. According to the Conceptual Metaphor Theory, abstract concepts tend to be understood with concrete experiences through embodied mappings. Therefore, the current study attempts to investigate how humor, an understudied abstract concept, is perceived in the Chinese context by means of textual analysis and a behavioral experiment. Firstly, 6,500 entries of the corpus data related to laughter and humor in Chinese were used for the textual analysis. Extensive uses of embodied humor metaphors were found, which provided important linguistic evidence for the interaction between laughter, humor, and body. Secondly, a behavioral study was conducted based on some frequently-used embodied metaphorical expressions of humor (e.g., pěngfù dàxiào 捧腹大笑, meaning ‘to hold one’s sides laughing’) identified in the corpus. Specifically, the participants were instructed to either do embodied metaphor or non-metaphor actions as bodily primes (i.e., ‘holding one’s belly while bending forward and backward repeatedly’ vs. ‘turning one’s upper body from side to side with both hands on the back’) or perform no actions before completing the subsequent joke rating task and the mood rating task. Results showed that the participants who were primed with the embodied metaphor actions rated the jokes higher than those in the control groups who were primed with non-metaphor actions or had no primes. Also, there was no significant difference in the mood ratings across the groups. These findings suggest that embodied humor metaphors indeed affect humor experience and shape how humor is conceptualized. The current study supports not only the embodied view of humor understanding but also the conceptual metaphor account of abstract reasoning, which sheds new light on the theoretical development of the embodiment of abstract concepts.

Is rushing always faster than strolling? A reaction time study on the processing of sentences containing manner of motion verbs

In the context of the embodied cognition debate, an effect of motion verb associated speed information has previously been detected using eye-tracking, functional magnetic resonance imaging (fMRI), and reaction times (RT). The latter, for instance, was implemented by Wender and Weber (1982), who observed that participants were faster in detecting motion in sentences associated with fast motion compared to sentences associated with slow motion after having formed mental images of the sentences' content. It remains open whether the reported effects of speed are associated with automatic lexical-semantic retrieval processes or whether they reflect higher top-down cognitive processes. To answer this question, the paradigm by Wender and Weber (1982) was adopted and further elaborated in the present study. In Experiment 1 visualization instructions were eliminated. Additionally, the stimulus material was manipulated in regards to the agent of the described movement (human vs. object motion) in order to determine the representation's modality (visual vs. motoric). In Experiment 2, the task to detect motion was replaced by the task to judge sensicality. The results suggest that the prompt to perform mental imagery is not a precondition for the engagement of modal representations in this speed of motion paradigm and that the involved representations' modality is visual rather than motoric. However, the modal representations' involvement is dependent on the task. They thus do not seem to be part of the invariant semantic representation of manner of motion verbs.

When the Action to Be Performed at the Stage of Retrieval Enacts Memory of Action Verbs

Abstract. According to the embodied approach of language, concepts are grounded in sensorimotor mental states, and when we process language, the brain simulates some of the perceptions and actions that are involved when interacting with real objects. Moreover, several studies have highlighted that cognitive performances are dependent on the overlap between the motor action simulated and the motor action required by the task. On the other hand, in the field of memory, the role of action is under debate. The aim of this work was to show that performing an action at the stage of retrieval influences memory performance in a recognition task (experiment 1) and a cued recall task (experiment 2), even if the participants were never instructed to consider the implied action. The results highlighted an action-based memory effect at the retrieval stage. These findings contribute to the debate about the implication of motor system in action verb processing and its role for memory.

Action verb processing specifically modulates motor behaviour and sensorimotor neuronal oscillations

Understanding action-related language recruits the brain’s motor system and can interact with motor behaviour. The current study shows MEG oscillatory patterns during verb-motor priming. Hand and foot verbs were followed by hand or foot responses, with faster reaction times for congruent conditions. In ROIs placed in the hand/arm and foot/leg portions of the sensorimotor cortex, this behavioural priming effect was accompanied by modulations in MEG oscillatory patterns preceding the responses. Power suppression in the alpha/beta frequency bands was reduced in congruent conditions in the body-part-specific ROIs. These results imply that the verb-motor priming effect may be a direct consequence of motor cortex contributions to action word processing.

Representation of action semantics in the motor cortex and Broca's area

Previous studies have shown that both reading action words and observing actions engage the motor cortex and Broca's area, but it is still controversial whether a somatotopic representation exists for action verbs within the motor cortex and whether Broca's area encodes action-specific semantics for verbs. Here we examined these two issues using a set of functional MRI experiments, including word reading, action observation and a movement localiser task. Results from multi-voxel pattern analysis (MVPA) showed a somatotopic organisation within the motor areas and action-specific activation in Broca's area for observed actions, suggesting the representation of action semantics for observed actions in these neural regions. For action verbs, however, a lack of finding for the somatotopic activation argues against semantic somatotopy within the motor cortex. Furthermore, activation patterns in Broca's area were not separable between action verbs and unrelated verbs, suggesting that Broca's area does not encode action-specific semantics for verbs.

For a cognitive neuroscience of concepts: Moving beyond the grounding issue

Cognitive neuroscience research on conceptual knowledge often is discussed with respect to "embodiment" or "grounding." We tried to disentangle at least three distinct claims made using these terms. One of these, the view that concepts are entirely reducible to sensory-motor representations, is untenable and diminishing in the literature. A second is the view that concepts and sensory-motor representations "interact," and a third view addresses the question of how concepts are neurally organized-the neural partitions among concepts of different kinds, and where these partitions are localized in cortex. We argue that towards the second and third issues, much fruitful research can be pursued, but that no position on them is specifically related to "grounding." Furthermore, to move forward on them, it is important to precisely distinguish different kinds of representations-conceptual vs. sensory-motor-from each other theoretically and empirically. Neuroimaging evidence often lacks such specificity. We take an approach that distinguishes conceptual from sensory-motor representations by virtue of two properties: broad generality and tolerance to the absence of sensory-motor associations. We review three of our recent experiments that employ these criteria in order to localize neural representations of several specific kinds of nonsensory attributes: functions, intentions, and belief traits. Building on past work, we find that neuroimaging evidence can be used fruitfully to distinguish interesting hypotheses about neural organization. On the other hand, most such evidence does not speak to any clear notion of "grounding" or "embodiment," because these terms do not make clear, specific, empirical predictions. We argue that cognitive neuroscience will proceed most fruitfully by relinquishing these terms.

Semantic discrimination impacts tDCS modulation of verb processing

Motor cortex activation observed during body-related verb processing hints at simulation accompanying linguistic understanding. By exploiting the up- and down-regulation that anodal and cathodal transcranial direct current stimulation (tDCS) exert on motor cortical excitability, we aimed at further characterizing the functional contribution of the motor system to linguistic processing. In a double-blind sham-controlled within-subjects design, online stimulation was applied to the left hemispheric hand-related motor cortex of 20 healthy subjects. A dual, double-dissociation task required participants to semantically discriminate concrete (hand/foot) from abstract verb primes as well as to respond with the hand or with the foot to verb-unrelated geometric targets. Analyses were conducted with linear mixed models. Semantic priming was confirmed by faster and more accurate reactions when the response effector was congruent with the verb's body part. Cathodal stimulation induced faster responses for hand verb primes thus indicating a somatotopical distribution of cortical activation as induced by body-related verbs. Importantly, this effect depended on performance in semantic discrimination. The current results point to verb processing being selectively modifiable by neuromodulation and at the same time to a dependence of tDCS effects on enhanced simulation. We discuss putative mechanisms operating in this reciprocal dependence of neuromodulation and motor resonance.

Communicative-Pragmatic Assessment Is Sensitive and Time-Effective in Measuring the Outcome of Aphasia Therapy

A range of methods in clinical research aim to assess treatment-induced progress in aphasia therapy. Here, we used a crossover randomized controlled design to compare the suitability of utterance-centered and dialogue-sensitive outcome measures in speech-language testing. Fourteen individuals with post-stroke chronic non-fluent aphasia each received two types of intensive training in counterbalanced order: conventional confrontation naming, and communicative-pragmatic speech-language therapy (Intensive Language-Action Therapy, an expanded version of Constraint-Induced Aphasia Therapy). Motivated by linguistic-pragmatic theory and neuroscience data, our dependent variables included a newly created diagnostic instrument, the Action Communication Test (ACT). This diagnostic instrument requires patients to produce target words in two conditions: (i) utterance-centered object naming, and (ii) communicative-pragmatic social interaction based on verbal requests. In addition, we administered a standardized aphasia test battery, the Aachen Aphasia Test (AAT). Composite scores on the ACT and the AAT revealed similar patterns of changes in language performance over time, irrespective of the treatment applied. Changes in language performance were relatively consistent with the AAT results also when considering both ACT subscales separately from each other. However, only the ACT subscale evaluating verbal requests proved to be successful in distinguishing between different types of training in our patient sample. Critically, testing duration was substantially shorter for the entire ACT (10–20 min) than for the AAT (60–90 min). Taken together, the current findings suggest that communicative-pragmatic methods in speech-language testing provide a sensitive and time-effective measure to determine the outcome of aphasia therapy.

EEG beta-power changes reflect motor involvement in abstract action language processing

Brain oscillations in the α- and β-range become suppressed during motor processing and motor imagery. It has recently been discussed that such power changes also occur during action language processing. In our study, we compared β₂-oscillations (16-25Hz) during the observation of prototypical arm movements (revealed via motion tracking) as well as during semantic processing of concrete and abstract sentences containing arm-related action verbs. Whereas we did find a strong desynchronization in the β₂-range during action observation, the processing of action sentences evoked a rather weak desynchronization. However, this desynchronization occurred for action verbs in both concrete and abstract contexts. These results might indicate a tendency for abstract action language to be processed similar to concrete action language rather than abstract sentences. The oscillation patterns reflect the close relationship between language comprehension and motor functions - one of the core claims of current theories on embodied cognition.

Does Motor Simulation Theory Explain the Cognitive Mechanisms Underlying Motor Imagery? A Critical Review

Motor simulation theory (MST; Jeannerod, 2001) purports to explain how various action-related cognitive states relate to actual motor execution. Specifically, it proposes that motor imagery (MI; imagining an action without executing the movements involved) shares certain mental representations and mechanisms with action execution, and hence, activates similar neural pathways to those elicited during the latter process. Furthermore, MST postulates that MI works by rehearsing neural motor systems off-line via a hypothetical simulation process. In this paper, we review evidence cited in support of MST and evaluate its efficacy in understanding the cognitive mechanisms underlying MI. In doing so, we delineate the precise postulates of simulation theory and clarify relevant terminology. Based on our cognitive-level analysis, we argue firstly that the psychological mechanisms underlying MI are poorly understood and require additional conceptual and empirical analysis. In addition, we identify a number of potentially fruitful lines of inquiry for future investigators of MST and MI.

Auditory perception modulated by word reading

Theories of embodied cognition positing that sensorimotor areas are indispensable during language comprehension are supported by neuroimaging and behavioural studies. Among others, the auditory system has been suggested to be important for understanding sound-related words (visually presented) and the motor system for action-related words. In this behavioural study, using a sound detection task embedded in a lexical decision task, we show that in participants with high lexical decision performance sound verbs improve auditory perception. The amount of modulation was correlated with lexical decision performance. Our study provides convergent behavioural evidence of auditory cortex involvement in word processing, supporting the view of embodied language comprehension concerning the auditory domain.

Sentence plausibility influences the link between action words and the perception of biological human movements

The present study aimed to assess the role of sentence plausibility in the functional link between action words and visual judgments of point-light human actions. Following the oral presentation of action verbs included in a plausible or implausible sentence, participants were asked to detect the presence of congruent or incongruent biological movements. Sentence plausibility was manipulated by inverting the positions of the subject and the complement (e.g., the neighbor is running in the garden vs the garden is running in the neighbor). The results showed that for both plausible and implausible sentences, the detection of human movements is greater following presentation of congruent action verbs. These results suggest that the presentation of action verbs affects the subsequent perception of point-light human movements, regardless of the associated semantic context. However, the link between action verbs and judgment of biological movements is strengthened when plausible sentences are presented, as illustrated by the increase in visual detection capacity in plausible congruent conditions. Concerning the analysis of the detection speed, the performance is only affected in plausible sentences with slower response times associated with the presentation of an incongruent action verb. These findings are discussed in light of an embodied mechanism and the domain of biological movement perception.