How embodied is action language? Neurological evidence from motor diseases

Unveiling the Diagnostic Potential of Linguistic Markers in Identifying Individuals with Parkinson's Disease through Artificial Intelligence: A Systematic Review

While extensive research has documented the cognitive changes associated with Parkinson's disease (PD), a relatively small portion of the empirical literature investigated the language abilities of individuals with PD. Recently, artificial intelligence applied to linguistic data has shown promising results in predicting the clinical diagnosis of neurodegenerative disorders, but a deeper investigation of the current literature available on PD is lacking. This systematic review investigates the nature of language disorders in PD by assessing the contribution of machine learning (ML) to the classification of patients with PD. A total of 10 studies published between 2016 and 2023 were included in this review. Tasks used to elicit language were mainly structured or unstructured narrative discourse. Transcriptions were mostly analyzed using Natural Language Processing (NLP) techniques. The classification accuracy (%) ranged from 43 to 94, sensitivity (%) ranged from 8 to 95, specificity (%) ranged from 3 to 100, AUC (%) ranged from 32 to 97. The most frequent optimal linguistic measures were lexico-semantic (40%), followed by NLP-extracted features (26%) and morphological consistency features (20%). Artificial intelligence applied to linguistic markers provides valuable insights into PD. However, analyzing measures derived from narrative discourse can be time-consuming, and utilizing ML requires specialized expertise. Moving forward, it is important to focus on facilitating the integration of both narrative discourse analysis and artificial intelligence into clinical practice.

Ecological Meanings: A Consensus Paper on Individual Differences and Contextual Influences in Embodied Language

Embodied theories of cognition consider many aspects of language and other cognitive domains as the result of sensory and motor processes. In this view, the appraisal and the use of concepts are based on mechanisms of simulation grounded on prior sensorimotor experiences. Even though these theories continue receiving attention and support, increasing evidence indicates the need to consider the flexible nature of the simulation process, and to accordingly refine embodied accounts. In this consensus paper, we discuss two potential sources of variability in experimental studies on embodiment of language: individual differences and context. Specifically, we show how factors contributing to individual differences may explain inconsistent findings in embodied language phenomena. These factors include sensorimotor or cultural experiences, imagery, context-related factors, and cognitive strategies. We also analyze the different contextual modulations, from single words to sentences and narratives, as well as the top-down and bottom-up influences. Similarly, we review recent efforts to include cultural and language diversity, aging, neurodegenerative diseases, and brain disorders, as well as bilingual evidence into the embodiment framework. We address the importance of considering individual differences and context in clinical studies to drive translational research more efficiently, and we indicate recommendations on how to correctly address these issues in future research. Systematically investigating individual differences and context may contribute to understanding the dynamic nature of simulation in language processes, refining embodied theories of cognition, and ultimately filling the gap between cognition in artificial experimental settings and cognition in the wild (i.e., in everyday life).

Narrative discourse production in Parkinson's disease: Decoupling the role of cognitive-linguistic and motor speech changes

Introduction

the interplay between neuropsychological and communicative abilities in Parkinson's disease (PD) has been relatively overlooked, and it is not entirely understood which difficulties are consequent to impaired motor control, and which have a linguistic/cognitive basis. Here, we examined narrative discourse in PD using a multi-level analysis procedure considering sentence-level (productivity, lexical-grammatical processing) and discourse-level processes (narrative organization, informativeness), and partialling out patients' motor speech impairments. The interaction between cognitive (i.e. linguistic and executive) and communication abilities was also investigated.

Methods

Twenty-nine PD subjects in the mild stage of the disease were compared to 29 matched healthy comparators (HC) on quantitative measures of narrative discourse derived from two picture description tasks. Multivariate (considering articulation rate and educational attainment as covariates) and univariate (with group membership as independent variable) analyses of variance were conducted on separate linguistic domains. The contribution of executive/linguistic abilities to PD's narrative performance was explored by multiple regression analyses on narrative measures significantly differentiating patients from HC.

Results

significant reductions in patients were observed on measures of productivity (less well-formed words, shorter sentences) and informativeness (fewer conceptual units, less informative elements, lower number of details) and these alterations were explained by variations in linguistic abilities (action and object naming) rather than executive abilities. Articulation rate and educational attainment did not impact the observed reduced productivity and under-informativeness.

Conclusion

referential narrative discourse is altered in PD, regardless of motor impairments in speech production. The observed reductions in productivity/informativeness aspects of narratives were related to naming abilities and in particular to verbs processing, consistently with the neurocognitive model of motor language coupling. Since narratives are amenable to recurrent and automated analysis for the identification of linguistic patterns potentially anticipating the development of PD and the onset of cognitive deterioration, discourse abilities should be quantitatively and repeatedly profiled in the disorder.

Spatiotemporal Dynamics of Activation in Motor and Language Areas Suggest a Compensatory Role of the Motor Cortex in Second Language Processing

The involvement of the motor cortex in language understanding has been intensively discussed in the framework of embodied cognition. Although some studies have provided evidence for the involvement of the motor cortex in different receptive language tasks, the role that it plays in language perception and understanding is still unclear. In the present study, we explored the degree of involvement of language and motor areas in a visually presented sentence comprehension task, modulated by language proficiency (L1: native language, L2: second language) and linguistic abstractness (literal, metaphorical, and abstract). Magnetoencephalography data were recorded from 26 late Chinese learners of English. A cluster-based permutation F test was performed on the amplitude of the source waveform for each motor and language region of interest (ROI). Results showed a significant effect of language proficiency in both language and motor ROIs, manifested as overall greater involvement of language ROIs (short insular gyri and planum polare of the superior temporal gyrus) in the L1 than the L2 during 300-500 ms, and overall greater involvement of motor ROI (central sulcus) in the L2 than the L1 during 600-800 ms. We interpreted the over-recruitment of the motor area in the L2 as a higher demand for cognitive resources to compensate for the inadequate engagement of the language network. In general, our results indicate a compensatory role of the motor cortex in L2 understanding.

Detecting Parkinson's disease and its cognitive phenotypes via automated semantic analyses of action stories

Action-concept outcomes are useful targets to identify Parkinson's disease (PD) patients and differentiate between those with and without mild cognitive impairment (PD-MCI, PD-nMCI). Yet, most approaches employ burdensome examiner-dependent tasks, limiting their utility. We introduce a framework capturing action-concept markers automatically in natural speech. Patients from both subgroups and controls retold an action-laden and a non-action-laden text (AT, nAT). In each retelling, we weighed action and non-action concepts through our automated Proximity-to-Reference-Semantic-Field (P-RSF) metric, for analysis via ANCOVAs (controlling for cognitive dysfunction) and support vector machines. Patients were differentiated from controls based on AT (but not nAT) P-RSF scores. The same occurred in PD-nMCI patients. Conversely, PD-MCI patients exhibited reduced P-RSF scores for both texts. Direct discrimination between patient subgroups was not systematic, but it yielded best outcomes via AT scores. Our approach outperformed classifiers based on corpus-derived embeddings. This framework opens scalable avenues to support PD diagnosis and phenotyping.

Tracing embodied word production in persons with Parkinson's disease in distinct motor conditions

Embodied cognition theories posit direct interactions between sensorimotor and mental processing. Various clinical observations have been interpreted in this controversial framework, amongst others, low verb generation in word production tasks performed by persons with Parkinson's disease (PD). If this were the consequence of reduced motor simulation of prevalent action semantics in this word class, reduced PD pathophysiology should result in increased verb production and a general shift of lexical contents towards particular movement-related meanings. 17 persons with PD and bilateral deep brain stimulation (DBS) of the subhtalamic nucleus (STN) and 17 healthy control persons engaged in a semantically unconstrained, phonemic verbal fluency task, the former in both DBS-off and DBS-on states. The analysis referred to the number of words produced, verb use, and the occurrence of different dimensions of movement-related semantics in the lexical output. Persons with PD produced fewer words than controls. In the DBS-off, but not in the DBS-on condition, the proportion of verbs within this reduced output was lower than in controls. Lowered verb production went in parallel with a semantic shift: in persons with PD in the DBS-off, but not the DBS-on condition, the relatedness of produced words to own body-movement was lower than in controls. In persons with PD, DBS induced-changes of the motor condition appear to go along with formal and semantic shifts in word production. The results are compatible with the idea of some impact of motor system states on lexical processing.

The action-sentence compatibility effect (ACE): Meta-analysis of a benchmark finding for embodiment

The embodied account of language comprehension has been one of the most influential theoretical developments in the recent decades addressing the question how humans comprehend and represent language. To examine its assumptions, many studies have made use of behavioral paradigms involving basic compatibility effects. The action-sentence compatibility effect (ACE) is one of the most influential of these compatibility effects and is the most widely cited evidence for the embodied account of language comprehension. However, recently there have been difficulties in extending or even in reliably replicating the ACE. The conflicting findings concerning the ACE and its extensions lead to the discussion of whether the ACE is indeed a reliable effect. In a first step we conducted a meta-analysis using a random-effects model. This analysis revealed a small but significant effect size of the ACE. Furthermore, the task-parameter Delay occurred as a factor of interest in whether the ACE appears with positive or negative effect direction. A second meta-analytic approach (Fisher's method) supports these findings. Additionally, an analysis of publication bias suggests that there is bias in the ACE literature. In post-hoc analyses of the recent multi-lab investigation of the ACE (Morey et al., 2021), evidence for individual differences in the ACE was found. However, further analyses indicate that these differences are likely due to item-specific variability and the specific way in which items were assigned to conditions in the counterbalancing lists.

Impaired processing of conspecifics in Parkinson's disease

Experimental evidence indicates that the inferior frontal gyrus (IFG) processes emotional/affective features crucial to elaborate knowledge about social groups and that knowledge of social concepts is stored in the anterior temporal lobe (ATL).We investigated whether knowledge about social groups is impaired in Parkinson's disease (PD), in which dysfunctional connectivity between IFG and ATL has been demonstrated.PD patients (N = 20) and healthy controls (HC, N = 16) were given a lexical decision task in a semantic priming paradigm: the prime-targets included 144 words and 144 pseudowords, each preceded by three types of prime ("animals," "things," "persons"). Out of these 288 prime-targets, forty-eight were congruent (same category) and 96 incongruent (different category). Out of 48 congruent prime-targets, 24 denoted social items and 24 nonsocial items. Thus, four types of trials were obtained: congruent social; congruent nonsocial; incongruent social; incongruent nonsocial.Congruent target-words were recognized better than incongruent target-words by all groups. The semantic priming effect was preserved in PD; however, accuracy was significantly lower in PD than in HC in social items. No difference emerged between the two groups in nonsocial items.Impaired processing of words denoting social groups in PD may be due to impairment in accessing the affective/emotional features that characterize conceptual knowledge of social groups, for the functional disconnection between the IFG and the ATL.

Action Fluency in Parkinson's Disease: A Mini-Review and Viewpoint

Increasing evidence shows that the typical motor symptoms of Parkinson's disease (PD) are often accompanied, if not preceded, by cognitive dysfunctions that are potentially linked to further complications of the disease. Notably, these cognitive dysfunctions appear to have a significant impact in the domain of action processing, as indicated by specific impairments for action-related stimuli in general, and verbs in particular. In this mini-review, we focus on the use of the action fluency test as a tool to investigate action processing, in PD patients. We discuss the current results within the embodied cognition framework and in relation to general action-related impairments in PD, while also providing an outlook on open issues and possible avenues for future research. We argue that jointly addressing action semantic processing and motor dysfunctions in PD patients could pave the way to interventions where the motor deficits are addressed to improve both motor and communicative skills since the early disease stages, with a likely significant impact on quality of life.

Structural and functional motor-network disruptions predict selective action-concept deficits: Evidence from frontal lobe epilepsy

Built on neurodegenerative lesions models, the disrupted motor grounding hypothesis (DMGH) posits that motor-system alterations selectively impair action comprehension. However, major doubts remain concerning the dissociability, neural signatures, and etiological generalizability of such deficits. Few studies have compared action-concept outcomes between disorders affecting and sparing motor circuitry, and none has examined their multimodal network predictors via data-driven approaches. Here, we first assessed action- and object-concept processing in patients with frontal lobe epilepsy (FLE), patients with posterior cortex epilepsy (PCE), and healthy controls. Then, we examined structural and functional network signatures via diffusion tensor imaging and resting-state connectivity measures. Finally, we used these measures to predict behavioral performance with an XGBoost machine learning regression algorithm. Relative to controls, FLE (but not PCE) patients exhibited selective action-concept deficits together with structural and functional abnormalities along motor networks. The XGBoost model reached a significantly large effect size only for action-concept outcomes in FLE, mainly predicted by structural (cortico-spinal tract, anterior thalamic radiation, uncinate fasciculus) and functional (M1-parietal/supramarginal connectivity) motor networks. These results extend the DMGH, suggesting that action-concept deficits are dissociable markers of frontal/motor (relative to posterior) disruptions, directly related to the structural and functional integrity of motor networks, and traceable beyond canonical movement disorders.

Semantic Memory and Lexical Availability in Parkinson's Disease: A Statistical Learning Study

Parkinson’s disease (PD) is a neurodegenerative disorder that causes a progressive impairment in motor and cognitive functions. Although semantic fluency deficits have been described in PD, more specific semantic memory (SM) and lexical availability (LA) domains have not been previously addressed. Here, we aimed to characterize the cognitive performance of PD patients in a set of SM and LA measures and determine the smallest set of neuropsychological (lexical, semantic, or executive) variables that most accurately classify groups. Thirty early-stage non-demented PD patients (age 35–75, 10 females) and thirty healthy controls (age 36–76, 12 females) were assessed via general cognitive, SM [three subtests of the CaGi battery including living (i.e., elephant) and non-living things (i.e., fork)], and LA (eliciting words from 10 semantic categories related to everyday life) measures. Results showed that PD patients performed lower than controls in two SM global scores (picture naming and naming in response to an oral description). This impairment was particularly pronounced in the non-living things subscale. Also, the number of words in the LA measure was inferior in PD patients than controls, in both larger and smaller semantic fields, showing a more inadequate recall strategy. Notably, the classification algorithms indicated that the SM task had high classification accuracy. In particular, the denomination of non-living things had a classification accuracy of ∼80%. These results suggest that frontostriatal deterioration in PD leads to search strategy deficits in SF and the potential disruption in semantic categorization. These findings are consistent with the embodied view of cognition.

Rekindling Action Language: A Neuromodulatory Study on Parkinson's Disease Patients

Impairments of action semantics (a cognitive domain that critically engages motor brain networks) are pervasive in early Parkinson's disease (PD). However, no study has examined whether action semantic skills in persons with this disease can be influenced by non-invasive neuromodulation. Here, we recruited 22 PD patients and performed a five-day randomized, blinded, sham-controlled study to assess whether anodal transcranial direct current stimulation (atDCS) over the primary motor cortex, combined with cognitive training, can boost action-concept processing. On day 1, participants completed a picture-word association (PWA) task involving action-verb and object-noun conditions. They were then randomly assigned to either an atDCS (n = 11, 2 mA for 20 m) or a sham tDCS (n = 11, 2 mA for 30 s) group and performed an online PWA practice over three days. On day 5, they repeated the initial protocol. Relative to sham tDCS, the atDCS group exhibited faster reaction times for action (as opposed to object) concepts in the post-stimulation test. This result was exclusive to the atDCS group and held irrespective of the subjects' cognitive, executive, and motor skills, further attesting to its specificity. Our findings suggest that action-concept deficits in PD are distinctively grounded in motor networks and might be countered by direct neuromodulation of such circuits. Moreover, they provide new evidence for neurosemantic models and inform a thriving agenda in the embodied cognition framework.

Functional connectivity of spoken language processing in early-stage Parkinson's disease: An MEG study

Parkinson's disease (PD) is a neurodegenerative disorder, well-known for its motor symptoms; however, it also adversely affects cognitive functions, including language, a highly important human ability. PD pathology is associated, even in the early stage of the disease, with alterations in the functional connectivity within cortico-subcortical circuitry of the basal ganglia as well as within cortical networks. Here, we investigated functional cortical connectivity related to spoken language processing in early-stage PD patients. We employed a patient-friendly passive attention-free paradigm to probe neurophysiological correlates of language processing in PD patients without confounds related to active attention and overt motor responses. MEG data were recorded from a group of newly diagnosed PD patients and age-matched healthy controls who were passively presented with spoken word stimuli (action and abstract verbs, as well as grammatically correct and incorrect inflectional forms) while focussing on watching a silent movie. For each of the examined linguistic aspects, a logistic regression classifier was used to classify participants as either PD patients or healthy controls based on functional connectivity within the temporo-fronto-parietal cortical language networks. Classification was successful for action verbs (accuracy = 0.781, p-value = 0.003) and, with lower accuracy, for abstract verbs (accuracy = 0.688, p-value = 0.041) and incorrectly inflected forms (accuracy = 0.648, p-value = 0.021), but not for correctly inflected forms (accuracy = 0.523, p-value = 0.384). Our findings point to quantifiable differences in functional connectivity within the cortical systems underpinning language processing in newly diagnosed PD patients compared to healthy controls, which arise early, in the absence of clinical evidence of deficits in cognitive or general language functions. The techniques presented here may aid future work on establishing neurolinguistic markers to objectively and noninvasively identify functional changes in the brain's language networks even before clinical symptoms emerge.

Does embodied cognition allow a better management of neurological diseases? A review on the link between cognitive language processing and motor function

Embodied cognition (EC) refers to the interplay occurring in thinking among individual's sensorimotor capacities (i.e., the ability of the body to respond to its senses with movement), the body itself, and the environment. The aim of the present narrative review is to provide an overall understanding of whether and how motor training could lead to language recovery, consistently with EC theories (action-perception cycle, mirror neuron systems -MNS-, and embodied semantics). We therefore reviewed the works dealing with EC in terms of the link between language processing, mirror neuron system (MNS), and motor function, evaluating the potential clinical implications for better managing neurological deficits. Connections between body and mind were found, as body states influence cognitive functions, such as perception and reasoning, as well as language processing, especially in neurological disorders. In fact, abnormalities in "embodied language" were found in movement disorders and neurodegenerative diseases, negatively affecting patients' rehabilitation outcomes. Understanding the link between language processing and motor outcomes is fundamental in the rehabilitation field, given that EC can be targeted to improve patients' functional recovery and quality of life.

Action fluency identifies different sex, age, global cognition, executive function and brain activation profile in non-demented patients with Parkinson's disease

Patients with Parkinson's disease (PD) have difficulties processing action words, which could be related to early cognitive decline. The action fluency test can be used to quickly and easily assess the processing of action words in PD. The goal of this study was to characterize how the action fluency test relates to personal characteristics, disease factors, cognition, and neural activity in PD. Forty-eight participants with PD (34 male, 14 female) and 35 control participants (16 male, 19 female) completed functional neuroimaging using a set-shifting task and a neuropsychological assessment including the action fluency test. PD participants with a score one standard deviation below the norm or lower on the action fluency test were identified. All PD participants with poor performance (PD-P, n = 15) were male. They were compared to male PD participants with scores within the normal range (PD-N, n = 19) and male healthy controls (HC, n = 16). PD-P were older, had lower global cognition scores, lower executive functions scores, and decreased activity in fronto-temporal regions compared with PD-N. There was no difference between the two PD groups in terms of the duration of the disease, dose of dopaminergic medication, and severity of motor symptoms. PD-N were younger than HC, but there was no other significant difference between these groups. The action fluency test identified a subgroup of PD patients with distinct sex, age, global cognition, executive functions, and brain activity characteristics. Implications for the evaluation of cognition are discussed.

From discourse to pathology: Automatic identification of Parkinson's disease patients via morphological measures across three languages

Embodied cognition research on Parkinson's disease (PD) points to disruptions of frontostriatal language functions as sensitive targets for clinical assessment. However, no existing approach has been tested for crosslinguistic validity, let alone by combining naturalistic tasks with machine-learning tools. To address these issues, we conducted the first classifier-based examination of morphological processing (a core frontostriatal function) in spontaneous monologues from PD patients across three typologically different languages. The study comprised 330 participants, encompassing speakers of Spanish (61 patients, 57 matched controls), German (88 patients, 88 matched controls), and Czech (20 patients, 16 matched controls). All subjects described the activities they perform during a regular day, and their monologues were automatically coded via morphological tagging, a computerized method that labels each word with a part-of-speech tag (e.g., noun, verb) and specific morphological tags (e.g., person, gender, number, tense). The ensuing data were subjected to machine-learning analyses to assess whether differential morphological patterns could classify between patients and controls and reflect the former's degree of motor impairment. Results showed robust classification rates, with over 80% of patients being discriminated from controls in each language separately. Moreover, the most discriminative morphological features were associated with the patients' motor compromise (as indicated by Pearson r correlations between predicted and collected motor impairment scores that ranged from moderate to moderate-to-strong across languages). Taken together, our results suggest that morphological patterning, an embodied frontostriatal domain, may be distinctively affected in PD across languages and even under ecological testing conditions.

Degradation of Praxis Brain Networks and Impaired Comprehension of Manipulable Nouns in Stroke

Distributed brain systems contribute to representation of semantic knowledge. Whether sensory and motor systems of the brain are causally involved in representing conceptual knowledge is an especially controversial question. Here, we tested 57 chronic left-hemisphere stroke patients using a semantic similarity judgment task consisting of manipulable and nonmanipulable nouns. Three complementary methods were used to assess the neuroanatomical correlates of semantic processing: voxel-based lesion-symptom mapping, resting-state functional connectivity, and gray matter fractional anisotropy. The three measures provided converging evidence that injury to the brain networks required for action observation, execution, planning, and visuomotor coordination are associated with specific deficits in manipulable noun comprehension relative to nonmanipulable items. Damage or disrupted connectivity of areas such as the middle posterior temporal gyrus, anterior inferior parietal lobe, and premotor cortex was related specifically to the impairment of manipulable noun comprehension. These results suggest that praxis brain networks contribute especially to the comprehension of manipulable object nouns.

The role of motor system in action-related language comprehension in L1 and L2: An fMRI study

The framework of embodied cognition has challenged the modular view of a language-cognition divide by suggesting that meaning-retrieval critically involves the sensory-motor system. Despite extensive research into the neural mechanisms underlying language-motor coupling, it remains unclear how the motor system might be differentially engaged by different levels of linguistic abstraction and language proficiency. To address this issue, we used fMRI to quantify neural activations in brain regions underlying motor and language processing in Chinese-English speakers' processing of literal, metaphorical, and abstract language in their L1 and L2. Results overall revealed a response in motor ROIs gradually attenuating in intensity from literal to abstract via metaphorical language in both L1 and L2. Furthermore, contrast analyses between L1 and L2 showed overall greater activations of motor ROIs in the L2. We conclude that motor involvement in language processing is graded rather than all-or-none and that the motor system has a dual-functional role.

Action Semantic Deficits and Impaired Motor Skills in Autistic Adults Without Intellectual Impairment

Several studies indicate the functional importance of the motor cortex for higher cognition, language and semantic processing, and place the neural substrate of these processes in sensorimotor action-perception circuits linking motor, sensory and perisylvian language regions. Interestingly, in individuals with autism spectrum disorder (ASD), semantic processing of action and emotion words seems to be impaired and is associated with hypoactivity of the motor cortex during semantic processing. In this study, the relationship between semantic processing, fine motor skills and clinical symptoms was investigated in 19 individuals with ASD and 22 typically-developing matched controls. Participants completed two semantic decision tasks involving words from different semantic categories, a test of alexithymia (the Toronto Alexithymia Scale), and a test of fine motor skills (the Purdue Pegboard Test). A significant Group × Word Category interaction in accuracy (p < 0.05) demonstrated impaired semantic processing for action words, but not object words in the autistic group. There was no significant group difference when processing abstract emotional words or abstract neutral words. Moreover, our study revealed deficits in fine motor skills as well as evidence for alexithymia in the ASD group, but not in neurotypical controls. However, these motor deficits did not correlate significantly with impairments in action-semantic processing. We interpret the data in terms of an underlying dysfunction of the action-perception system in ASD and its specific impact on semantic language processing.

A dissociation between syntactic and lexical processing in Parkinson's disease

Parkinson's disease (PD), which involves the degeneration of dopaminergic neurons in the basal ganglia, has long been associated with motor deficits. Increasing evidence suggests that language can also be impaired, including aspects of syntactic and lexical processing. However, the exact pattern of these impairments remains somewhat unclear, for several reasons. Few studies have examined and compared syntactic and lexical processing within subjects, so their relative deficits remain to be elucidated. Studies have focused on earlier stages of PD, so syntactic and lexical processing in later stages are less well understood. Research has largely probed English and a handful of other European languages, and it is unclear whether findings generalize more broadly. Finally, few studies have examined links between syntactic/lexical impairments and their neurocognitive substrates, such as measures of basal ganglia degeneration or dopaminergic processes. We addressed these gaps by investigating multiple aspects of Farsi syntactic and lexical processing in 40 Farsi native-speaking moderate-to-severe non-demented PD patients, and 40 healthy controls. Analyses revealed equivalent impairments of syntactic comprehension and syntactic judgment, across different syntactic structures. Lexical processing was impaired only for motor function-related objects (e.g., naming 'hammer', but not 'mountain'), in line with findings of PD deficits at naming action verbs as compared to objects, without the verb/noun confound. In direct comparisons between lexical and syntactic tasks, patients were better at naming words like 'mountain' (but not words like 'hammer') than at syntactic comprehension and syntactic judgment. Performance at syntactic comprehension correlated with the last levodopa equivalent dose. No other correlations were found between syntactic/lexical processing measures and either levodopa equivalent dose or hypokinesia, which reflects degeneration of basal ganglia motor-related circuits. All critical significant main effects, interactions, and correlations yielded large effect sizes. The findings elucidate the nature of syntactic and lexical processing impairments in PD.

Information Content and Efficiency in the Spoken Discourse of Individuals With Parkinson's Disease

PURPOSE

This study compared the information content and information efficiency of spoken language in individuals with Parkinson's disease (PD) to a healthy comparator group.

METHOD

Nineteen participants with PD and 19 healthy older adults completed the prospective, cross-sectional study. In the primary analysis, 2 language samples elicited by standardized protocols were analyzed for group differences using standard discourse informativeness measures including main events (MEs; Wright, Capilouto, Wagovich, Cranfill, & Davis, 2005) analyzed as %MEs and correct information units (CIUs; Nicholas & Brookshire, 1993) analyzed as %CIUs and CIUs/min. In exploratory analyses, the following were examined: (a) associations among conceptual (%MEs) and lexical (%CIUs and CIUs/min) measures and (b) associations among informativeness measures and age, education, disease severity/duration, global cognition, speech intelligibility, and a verb confrontation naming measure.

RESULTS

In the primary analysis, the PD group differed significantly from the control group on conceptual (%MEs) and lexical measures of content (%CIUs) and efficiency (CIUs/min). In exploratory analyses, for the control group %MEs were significantly correlated with CIUs/min. Significant associations among conceptual and lexical measures of informativeness were not found in the PD group. For controls, there were no significant correlations between informativeness measures and any of the demographic or speech/cognitive/language variables. In the PD group, there was a significant and positive association between CIUs/min and Dementia Rating Scale-Second Edition scores (Mattis, 2001). A significant but negative correlation was found between CIUs/min and motor severity scores. However, %MEs and verb naming were significantly and positively correlated.

CONCLUSIONS

Individuals with PD without dementia demonstrated reduced discourse informativeness that reflects disruptions to both conceptual and lexical discourse processes. In exploratory analyses, reduced efficiency of information content was associated with global cognition and motor severity. Clinical and research implications are discussed within a Cognitivist framework of discourse production (Sheratt, 2007).

The strength of weak embodiment

While popular within some cognitive science approaches, the embodiment approach has still found resistance, particularly in light of evidence arguing against strong forms of embodiment. Among other things, the embodiment approach breaks away from the Cartesian ontology of the modulatory system. We claim that the advantages of the embodiment approach are: a) it grounds cognition into modal experience, b) it is harmonious with a materialist philosophy of mind (emergent materialism), and c) it is supported by experimental research in various fields. However, embodiment must still address abstractions, theoretical misunderstandings (representations vs non-representations) and neuroscientific findings that challenge the extension and relevance of sensorimotor properties into cognitive processes. While the strong version of embodiment is seriously challenged by conceptual and physiological setbacks, its weak version is supported by compelling evidence. We suggest future research focus on the psychophysiological bases of grounded cognition and redirect efforts towards the field of cross-modal correspondence.

Progressive Compromise of Nouns and Action Verbs in Posterior Cortical Atrophy

Processing of nouns and action verbs can be differentially compromised following lesions to posterior and anterior/motor brain regions, respectively. However, little is known about how these deficits progress in the course of neurodegeneration. To address this issue, we assessed productive lexical skills in a patient with posterior cortical atrophy (PCA) at two different stages of his pathology. On both occasions, he underwent a structural brain imaging protocol and completed semantic fluency tasks requiring retrieval of animals (nouns) and actions (verbs). Imaging results were compared with those of controls via voxel-based morphometry (VBM), whereas fluency performance was compared to age-matched norms through Crawford's t-tests. In the first assessment, the patient exhibited atrophy of more posterior regions supporting multimodal semantics (medial temporal and lingual gyri), together with a selective deficit in noun fluency. Then, by the second assessment, the patient's atrophy had progressed mainly toward fronto-motor regions (rolandic operculum, inferior and superior frontal gyri) and subcortical motor hubs (cerebellum, thalamus), and his fluency impairments had extended to action verbs. These results offer unprecedented evidence of the specificity of the pathways related to noun and action-verb impairments in the course of neurodegeneration, highlighting the latter's critical dependence on damage to regions supporting motor functions, as opposed to multimodal semantic processes.

Selection Processing in Noun and Verb Production in Left- and Right-Sided Parkinson's Disease Patients

Verbs are more difficult to produce than nouns. Thus, if executive resources are reduced as in Parkinson's disease (PD), verbs are penalized compared to nouns. However, in an experimental condition in which it is the noun that must be selected from a larger number of alternatives compared to the verb, it is the noun production that becomes slower and more prone to errors. Indeed, patients are slower and less accurate than normal subjects when required to produce nouns from verbs (VN) in a morphology derivation tasks (e.g., "osservazione" from "osservare") ["observation" from "observe"] than verbs from nouns in a morphology generation task, in which only a verb can be generated from the noun (NV) (e.g., "fallire" from "fallimento") ["to fail" from "failure"]. In the Italian language morphology, in fact, generation and derivation tasks differ in the number of lexical entries among which the response must be selected. The left Inferior Frontal Gyrus (IFG) has been demonstrated to be involved in selection processes. In the present study, we explored if the ability to select words is related to the cortical thickness of the left IFG. Twelve right-sided PD with nigrostriatal hypofunctionality in the left hemisphere (RPD-LH), 9 left-sided PD with nigrostriatal hypofunctionality in the right hemisphere (LPD-RH) and 19 healthy controls (HC) took part in the study. NV and VN production tasks were administered; accuracy and reaction times (RTs) were collected. All 40 subjects received a structural MRI examination. Cortical thickness of the IFG and volumetric measurements for subcortical regions, thought to support selection processes, were computed using FreeSurfer. In VN derivation tasks RPD-LH patients were less accurate than LPD-RH patients (accuracy: 66% vs. 77%). No difference emerged among the three groups in RTs. Task accuracy/RTs and IFG thickness showed a significant correlation only in RPD-LH. Not only nouns (as expected) but also verbs were correlated with cortical thickness. This suggests that the linguistic nature of the stimuli along with executive resources are both relevant during word selection processes. Our data confirm that executive resources and language interact in the left IFG in word production tasks.

Action Semantics at the Bottom of the Brain: Insights From Dysplastic Cerebellar Gangliocytoma

Recent embodied cognition research shows that access to action verbs in shallow-processing tasks becomes selectively compromised upon atrophy of the cerebellum, a critical motor region. Here we assessed whether cerebellar damage also disturbs explicit semantic processing of action pictures and its integration with ongoing motor responses. We evaluated a cognitively preserved 33-year-old man with severe dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease), encompassing most of the right cerebellum and the posterior part of the left cerebellum. The patient and eight healthy controls completed two semantic association tasks (involving pictures of objects and actions, respectively) that required motor responses. Accuracy results via Crawford’s modified t-tests revealed that the patient was selectively impaired in action association. Moreover, reaction-time analysis through Crawford’s Revised Standardized Difference Test showed that, while processing of action concepts involved slower manual responses in controls, no such effect was observed in the patient, suggesting that motor-semantic integration dynamics may be compromised following cerebellar damage. Notably, a Bayesian Test for a Deficit allowing for Covariates revealed that these patterns remained after covarying for executive performance, indicating that they were not secondary to extra-linguistic impairments. Taken together, our results extend incipient findings on the embodied functions of the cerebellum, offering unprecedented evidence of its crucial role in processing non-verbal action meanings and integrating them with concomitant movements. These findings illuminate the relatively unexplored semantic functions of this region while calling for extensions of motor cognition models.

Is procedural memory enhanced in Tourette syndrome? Evidence from a sequence learning task

Procedural memory, which is rooted in the basal ganglia, underlies the learning and processing of numerous automatized motor and cognitive skills, including in language. Not surprisingly, disorders with basal ganglia abnormalities have been found to show impairments of procedural memory. However, brain abnormalities could also lead to atypically enhanced function. Tourette syndrome (TS) is a candidate for enhanced procedural memory, given previous findings of enhanced TS processing of grammar, which likely depends on procedural memory. We comprehensively examined procedural learning, from memory formation to retention, in children with TS and typically developing (TD) children, who performed an implicit sequence learning task over two days. The children with TS showed sequence learning advantages on both days, despite a regression of sequence knowledge overnight to the level of the TD children. This is the first demonstration of procedural learning advantages in any disorder. The findings may further our understanding of procedural memory and its enhancement. The evidence presented here, together with previous findings suggesting enhanced grammar processing in TS, underscore the dependence of language on a system that also subserves visuomotor sequencing.

Words That Move Us. The Effects of Sentences on Body Sway

According to the embodied cognition perspective, cognitive systems and perceptuo-motor systems are deeply intertwined and exert a causal effect on each other. A prediction following from this idea is that cognitive activity can result in subtle changes in observable movement. In one experiment, we tested whether reading various sentences resulted in changes in postural sway. Sentences symbolized various human activities involving high, low, or no physical effort. Dutch participants stood upright on a force plate, measuring the body center of pressure, while reading a succession of sentences. High physical effort sentences resulted in more postural sway (greater SD) than low physical effort sentences. This effect only showed up in medio-lateral sway but not anterio-posterior sway. This suggests that sentence comprehension was accompanied by subtle motoric activity, likely mirroring the various activities symbolized in the sentences. We conclude that semantic processing reaches the motor periphery, leading to increased postural activity.

A Novel Integrating Virtual Reality Approach for the Assessment of the Attachment Behavioral System

Virtual reality (VR) technology represents a novel and powerful tool for behavioral research in psychological assessment. VR provides simulated experiences able to create the sensation of undergoing real situations. Users become active participants in the virtual environment seeing, hearing, feeling, and actuating as if they were in the real world. Currently, the most psychological VR applications concern the treatment of various mental disorders but not the assessment, that it is mainly based on paper and pencil tests. The observation of behaviors is costly, labor-intensive, and it is hard to create social situations in laboratory settings, even if the observation of actual behaviors could be particularly informative. In this framework, social stressful experiences can activate various behaviors of attachment for a significant person that can help to control and soothe them to promote individual’s well-being. Social support seeking, physical proximity, and positive and negative behaviors represent the main attachment behaviors that people can carry out during experiences of distress. We proposed VR as a novel integrating approach to measure real attachment behaviors. The first studies on attachment behavioral system by VR showed the potentiality of this approach. To improve the assessment during the VR experience, we proposed virtual stealth assessment (VSA) as a new method. VSA could represent a valid and novel technique to measure various psychological attributes in real-time during the virtual experience. The possible use of this method in psychology could be to generate a more complete, exhaustive, and accurate individual’s psychological evaluation.

Word selection processing in Parkinson's disease: When nouns are more difficult than verbs

Patients with Parkinson's disease (PD) are impaired in verb production. Interpretations range from grammatical deficits to semantic-conceptual decay of action representation. The verb production deficit in PD can also be considered a dysexecutive disorder, specifically, a deficit of selection processing during word production, due to corticostriatal damage. Producing verbs is "more difficult" than producing nouns, because verb-forms must be selected from a large set of word-forms which share the verb-root, and the set of possible verb-forms is larger than the set of possible noun-forms when a noun has to be produced. However, if we devise a condition in which a noun must be selected from a set of alternatives larger than the set of alternative forms from which a verb must be selected, we expect an opposite pattern, with nouns becoming more difficult than verbs. We used morphological tasks varying in the number of alternative responses during word production. Fourteen PD patients and 14 healthy Controls participated in the study. Participants performed a noun-from-verb ('observation' from 'to observe') and a noun-from adjective derivation task ('kindness' from 'kind'), and a verb-from-noun ('to observe' from 'observation') and an adjective-from-noun generation task ('kind' from 'kindness'). Input-stimuli were presented singularly on a screen and participants produced the response as fast as possible. Response latencies were longer in derivation tasks (several alternative responses) than in generation tasks (one possible response), irrespective of the grammatical class of the target word, with no difference between groups. PD patients were significantly less accurate than Controls only in the noun-from-verb derivation task, that is, in the task with the highest number of alternative responses (PD: 60%; Controls: 81%). Results suggest that the verb production disorder in PD patients may reflect disturbed selection processes among competitors: the higher the number of alternative responses the more severe the impairment.

Impaired Comprehension of Speed Verbs in Parkinson's Disease

OBJECTIVES

A wealth of studies provide evidence for action simulation during language comprehension. Recent research suggests such action simulations might be sensitive to fine-grained information, such as speed. Here, we present a crucial test for action simulation of speed in language by assessing speed comprehension in patients with Parkinson's disease (PD). Based on the patients' motor deficits, we hypothesized that the speed of motion described in language would modulate their performance in semantic tasks. Specifically, they would have more difficulty processing language about relatively fast speed than language about slow speed.

METHODS

We conducted a semantic similarity judgment task on fast and slow action verbs in patients with PD and age-matched healthy controls. Participants had to decide which of two verbs most closely matched a target word.

RESULTS

Compared to controls, PD patients were slower making judgments about fast action verbs, but not for judgments about slow action verbs, suggesting impairment in processing language about fast action. Moreover, this impairment was specific to verbs describing fast action performed with the hand.

CONCLUSIONS

Problems moving quickly lead to difficulties comprehending language about moving quickly. This study provides evidence that speed is an important part of action representations. (JINS, 2017, 23, 412-420).

Action-semantic and syntactic deficits in subjects at risk for Huntington's disease

Frontostriatal networks play critical roles in grounding action semantics and syntactic skills. Indeed, their atrophy distinctively disrupts both domains, as observed in patients with Huntington's disease (HD) and Parkinson's disease, even during early disease stages. However, frontostriatal degeneration in these conditions may begin up to 15 years before the onset of clinical symptoms, opening avenues for pre-clinical detection via sensitive tasks. Such a mission is particularly critical in HD, given that patients' children have 50% chances of inheriting the disease. Against this background, we assessed whether deficits in the above-mentioned domains emerge in subjects at risk to develop HD. We administered tasks tapping action semantics, object semantics, and two forms of syntactic processing to 18 patients with HD, 19 asymptomatic first-degree relatives, and sociodemographically matched controls for each group. The patients evinced significant deficits in all tasks, but only those in the two target domains were independent of overall cognitive state. More crucially, relative to controls, the asymptomatic relatives were selectively impaired in action semantics and in the more complex syntactic task, with both patterns emerging irrespective of the subjects' overall cognitive state. Our findings highlight the relevance of these dysfunctions as potential prodromal biomarkers of HD. Moreover, they offer theoretical insights into the differential contributions of frontostriatal hubs to both domains while paving the way for innovations in diagnostic procedures.

Effect of Constrained Arm Posture on the Processing of Action Verbs

Evidence is increasing that brain areas that are responsible for action planning and execution are activated during the information processing of action-related verbs (e.g., pick or kick). To obtain further evidence, we conducted three experiments to see if constraining arm posture, which could disturb the motor planning and imagery for that arm, would lead to delayed judgment of verbs referring to arm actions. In all experiments, native Japanese speakers judged as quickly as possible whether the presented object and the verb would be compatible (e.g., ball–throw) or not (e.g., ball–pour). Constrained arm posture was introduced to the task by asking participants to keep both hands behind their back. Two types of verbs were used: manual action verbs (i.e., verbs referring to actions performed on an object by a human hand) and non-manual action verbs. In contrast to our hypothesis that constrained arm posture would affect only the information processing of manual action verbs, the results showed delayed processing of both manual action and non-manual action verbs when the arm posture was constrained. The effect of constrained arm posture was observed even when participants responded with their voice, suggesting that the delayed judgment was not simply due to the difficulty of responding with the hand (i.e., basic motor interference). We discussed why, contrary to our hypothesis, constrained arm posture resulted in delayed CRTs regardless of the “manipulability” as symbolized by the verbs.

Attention to body-parts varies with visual preference and verb-effector associations

Theories of embodied conceptual meaning suggest fundamental relations between others' actions, language, and our own actions and visual attention processes. Prior studies have found that when people view an image of a neutral body in a scene they first look toward, in order, the head, torso, hands, and legs. Other studies show associations between action verbs and the body-effectors used in performing the action (e.g., "jump" with feet/legs; "talk" with face/head). In the present experiment, the visual attention of participants was recorded with a remote eye-tracking system while they viewed an image of an actor pantomiming an action and heard a concrete action verb. Participants manually responded whether or not the action image was a good example of the verb they heard. The eye-tracking results confirmed that participants looked at the head most, followed by the hands, and the feet least of all; however, visual attention to each of the body-parts also varied as a function of the effector associated with the spoken verb on image/verb congruent trials, particularly for verbs associated with the legs. Overall, these results suggest that language influences some perceptual processes; however, hearing auditory verbs did not alter the previously reported fundamental hierarchical sequence of directed attention, and fixations on specific body-effectors may not be essential for verb comprehension as peripheral visual cues may be sufficient to perform the task.

Lexical-retrieval and semantic memory in Parkinson's disease: The question of noun and verb dissociation

The dissociation between the processing of verbs and nouns has been debated in light of the Embodied Cognition Theory (EC). The objective of this paper is to verify how action and verb processing deficits of PD patients are modulated by different tasks with different cognitive demands. Action and object lexical-semantic processing was evaluated in patients with Parkinson's Disease (PD) and cognitively healthy controls through three different tasks (verbal fluency, naming and semantic association). Compared to controls, PD patients presented worse performance in naming actions and in the two semantic association tasks (action/object). Action verbal fluency performance was significantly associated with PD severity whereas object semantic association deficits and noun verbal fluency scores were associated to lower scores in measures of global cognitive functioning. Our data suggest that semantic deficits are related to the type of cognitive processing and this is in the line with more flexible EC accounts.

Language Deficits as a Preclinical Window into Parkinson's Disease: Evidence from Asymptomatic Parkin and Dardarin Mutation Carriers

OBJECTIVES

The worldwide spread of Parkinson's disease (PD) calls for sensitive and specific measures enabling its early (or, ideally, preclinical) detection. Here, we use language measures revealing deficits in PD to explore whether similar disturbances are present in asymptomatic individuals at risk for the disease.

METHODS

We administered executive, semantic, verb-production, and syntactic tasks to sporadic PD patients, genetic PD patients with PARK2 (parkin) or LRRK2 (dardarin) mutation, asymptomatic first-degree relatives of the latter with similar mutations, and socio-demographically matched controls. Moreover, to detect sui generis language disturbances, we ran analysis of covariance tests using executive functions as covariate.

RESULTS

The two clinical groups showed impairments in all measures, most of which survived covariation with executive functions. However, the key finding concerned asymptomatic mutation carriers. While these subjects showed intact executive, semantic, and action-verb production skills, they evinced deficits in a syntactic test with minimal working memory load.

CONCLUSIONS

We propose that this sui generis disturbance may constitute a prodromal sign anticipating eventual development of PD. Moreover, our results suggest that mutations on specific genes (PARK2 and LRRK2) compromising basal ganglia functioning may be subtly related to language-processing mechanisms. (JINS, 2017, 23, 150-158).

Developmental Coordination Disorder Affects the Processing of Action-Related Verbs

Processing action-language affects the planning and execution of motor acts, which suggests that the motor system might be involved in action-language understanding. However, this claim is hotly debated. For the first time, we compared the processing of action-verbs in children with Developmental Coordination Disorder (DCD), a disease that specifically affects the motor system, with children with a typical development (TD). We administered two versions of a go/no-go task in which verbs expressing either hand, foot or abstract actions were presented. We found that only when the semantic content of a verb has to be retrieved, TD children showed an increase in reaction times if the verb involved the same effector used to give the response. In contrast, DCD patients did not show any difference between verb categories irrespective of the task. These findings suggest that the pathological functioning of the motor system in individuals with DCD also affects language processing.

A Lesion-Proof Brain? Multidimensional Sensorimotor, Cognitive, and Socio-Affective Preservation Despite Extensive Damage in a Stroke Patient

In this study, we report an unusual case of mutidimensional sensorimotor, cognitive, and socio-affective preservation in an adult with extensive, acquired bilateral brain damage. At age 43, patient CG sustained a cerebral hemorrhage and a few months later, she suffered a second (ischemic) stroke. As a result, she exhibited extensive damage of the right hemisphere (including frontal, temporal, parietal, and occipital regions), left Sylvian and striatal areas, bilateral portions of the insula and the amygdala, and the splenium. However, against all probability, she was unimpaired across a host of cognitive domains, including executive functions, attention, memory, language, sensory perception (e.g., taste recognition and intensity discrimination), emotional processing (e.g., experiencing of positive and negative emotions), and social cognition skills (prosody recognition, theory of mind, facial emotion recognition, and emotional evaluation). Her functional integrity was further confirmed through neurological examination and contextualized observation of her performance in real-life tasks. In sum, CG's case resists straightforward classifications, as the extent and distribution of her lesions would typically produce pervasive, multidimensional deficits. We discuss the rarity of this patient against the backdrop of other reports of atypical cognitive preservation, expound the limitations of several potential accounts, and highlight the challenges that the case poses for current theories of brain organization and resilience.

A touch with words: Dynamic synergies between manual actions and language

Manual actions are a hallmark of humanness. Their underlying neural circuitry gives rise to species-specific skills and interacts with language processes. In particular, multiple studies show that hand-related expressions - verbal units evoking manual activity - variously affect concurrent manual actions, yielding apparently controversial results (interference, facilitation, or null effects) in varied time windows. Through a systematic review of 108 experiments, we show that such effects are driven by several factors, such as the level of verbal processing, action complexity, and the time-lag between linguistic and motor processes. We reconcile key empirical patterns by introducing the Hand-Action-Network Dynamic Language Embodiment (HANDLE) model, an integrative framework based on neural coupling dynamics and predictive-coding principles. To conclude, we assess HANDLE against the backdrop of other action-cognition theories, illustrate its potential applications to understand high-level deficits in motor disorders, and discuss key challenges for further development. In sum, our work aligns with the 'pragmatic turn', moving away from passive and static representationalist perspectives to a more dynamic, enactive, and embodied conceptualization of cognitive processes.

Hands typing what hands do: Action-semantic integration dynamics throughout written verb production

Processing action verbs, in general, and manual action verbs, in particular, involves activations in gross and hand-specific motor networks, respectively. While this is well established for receptive language processes, no study has explored action-semantic integration during written production. Moreover, little is known about how such crosstalk unfolds from motor planning to execution. Here we address both issues through our novel "action semantics in typing" paradigm, which allows to time keystroke operations during word typing. Specifically, we created a primed-verb-copying task involving manual action verbs, non-manual action verbs, and non-action verbs. Motor planning processes were indexed by first-letter lag (the lapse between target onset and first keystroke), whereas execution dynamics were assessed considering whole-word lag (the lapse between first and last keystroke). Each phase was differently delayed by action verbs. When these were processed for over one second, interference was strong and magnified by effector compatibility during programming, but weak and effector-blind during execution. Instead, when they were processed for less than 900ms, interference was reduced by effector compatibility during programming and it faded during execution. Finally, typing was facilitated by prime-target congruency, irrespective of the verbs' motor content. Thus, action-verb semantics seems to extend beyond its embodied foundations, involving conceptual dynamics not tapped by classical reaction-time measures. These findings are compatible with non-radical models of language embodiment and with predictions of event coding theory.

The Influence of Motor Imagery on Postural Sway: Differential Effects of Type of Body Movement and Person Perspective

The present study examined the differential effects of kinesthetic imagery (first person perspective) and visual imagery (third person perspective) on postural sway during quiet standing. Based on an embodied cognition perspective, the authors predicted that kinesthetic imagery would lead to activations in movement-relevant motor systems to a greater degree than visual imagery. This prediction was tested among 30 participants who imagined various motor activities from different visual perspectives while standing on a strain gauge plate. The results showed that kinesthetic imagery of lower body movements, but not of upper body movements, had clear effects on postural parameters (sway path length and frequency contents of sway). Visual imagery, in contrast, had no reliable effects on postural activity. We also found that postural effects were not affected by the vividness of imagery. The results suggest that during kinesthetic motor imagery participants partially simulated (re-activated) the imagined movements, leading to unintentional postural adjustments. These findings are consistent with an embodied cognition perspective on motor imagery.