Spontaneous gestures following right hemisphere infarct

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

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

Production of co-speech gestures in the right hemisphere: Evidence from individuals with complete or anterior callosotomy

INTRODUCTION

A right-hand preference for co-speech gestures in right-handed neurotypical individuals as well as the co-occurrence of speech and gesture has induced neuropsychological research to primarily target the left hemisphere when investigating co-speech gesture production. However, the substantial number of spontaneous left-hand gestures in right-handed individuals has, thus far, been unexplained. Recent studies in individuals with complete callosotomy and exclusive left hemisphere speech production show a reliable left-hand preference for co-speech gestures, indicating a right hemispheric generation. However, the findings raise the issue if the separate right hemisphere is able to also generate representational gestures. The present study challenges the proposition of a specific right hemispheric contribution to gesture production by differentiating gesture types including representational ones in individuals with complete callosotomy and by including individuals with anterior callosotomy in whom neural reorganization is less extensive.

METHODS

Three right-handed individuals with complete commissurotomy (A.A., N.G., G.C.) and three right-handed individuals with anterior callosotomy (C.E., S.R., L. D), all with left hemisphere language dominance, and a matched right-handed neurotypical control group (n = 10) were examined in an experimental setting, including re-narration of a nonverbal animated cartoon and responding to intelligence questions. The participants' video-taped hand movement behavior was analyzed by two independent certified raters with the NEUROGES-ELAN system for nonverbal behavior and gesture. Unimanual right-hand and left-hand gestures were classified into eight gesture types.

RESULTS

The individuals with complete and anterior callosotomy performed unimanual co-speech gestures with the left as well as the right hand, with no significant preference of one hand for gestures overall. Concerning the specific gesture types, the group with complete callosotomy showed a significant right-hand preference for pantomime gestures, which also applied to the callosotomy total group. The group with anterior callosotomy displayed a significant left-hand preference for form presentation gestures. As a trend, the callosotomy total group differed from the neurotypical group as they performed more left-hand egocentric deictic and left-hand form presentation gestures.

DISCUSSION

The present study replicates the finding of a substantial left-hand use for unimanual co-speech gestures in individuals with complete callosotomy. The proposition of a right hemispheric contribution to gesture production independent from left hemispheric language production is corroborated by the finding that individuals with anterior callosotomy show a similar pattern of hand use for gestures. Representational gestures were displayed with either hand, suggesting that in particular right hemispheric spatial cognition can be directly expressed in gesture. The significant right-hand preference for pantomime gesture was outstanding and compatible with the established left hemispheric specialization for tool use praxis. The findings shed a new light on the left-hand gestures in neurotypical individuals, suggesting that these can be generated in the right hemisphere.

Unaided communication behaviours displayed by adults with severe cerebrovascular accidents and little or no functional speech: A scoping review

BACKGROUND

Unaided communication behaviours may provide communication support for persons with severe cerebrovascular accidents (CVA), as these individuals often experience severe communication difficulties, regardless of the aetiology. Though often subtle, these behaviours are present during all stages of recovery, and therefore communication partners need to know not only which unaided strategies are used as communication attempts, but also what their function is (i.e., what the person aims to achieve with the communication).

AIM

To identify the unaided communication behaviours that adults with severe CVA and little or no functional speech use to communicate, and to determine the communication functions addressed by these behaviours.

METHODS & PROCEDURES

The study used a scoping review methodology and included articles on communication partners of persons with CVA published between 1986 and 2020. Initially the searches yielded 732 studies from which 211 duplicates were identified. The remaining studies (n = 531) were then screened on title, abstract and full-text level resulting in a final inclusion of 18 studies. Of the 18 studies, five were qualitative and 13 consisted of quantitative methodologies.

MAIN CONTRIBUTION

The subtle communication behaviours used by persons with CVA (and resultant severe communication difficulties) are often misinterpreted or overlooked by their partners. If partners are trained to recognise such subtle or unaided communication behaviours, they can provide adequate support to access a range of communication functions. The unaided communication behaviours, which include 13 primary behaviours ranging from non-linguistic to linguistic, were utilised to convey 31 communication functions classified into four main communication categories.

CONCLUSIONS & IMPLICATIONS

Although unaided communication behaviours often appear as limiting, they can be utilised to communicate various communication functions. The findings of this review support the training of partners to identify these behaviours and improve person-partner communication. WHAT IS KNOWN?: Unaided communication has been widely researched. However, a summary is needed of the various unaided communication behaviours and of the different communication functions addressed by these behaviours. What the paper adds… This paper emphasises that unaided communication behaviours range from non-linguistic to linguistic, and they can support unintentional, pre-intentional and intentional communication functions. Clinical implications Even though aided communication is preferred, unaided communication behaviours are generally used in contexts with limited resources, as well as among culturally and linguistically diverse populations. This study advocates the identification of unaided communication behaviours by partners as well as the support and provision of access to communication strategies for persons with severe CVA. Future research should include more untrained communication partners.

Hemispheric specialization for nonverbal gestures depicting motion and space

INTRODUCTION

The right hemispheric specialisation for mental rotation suggests a left hand preference for nonverbal gestures that depict spatial information. We therefore hypothesized that nonverbal depictions of spatial information are preferentially demonstrated by the left hand, i.e., are grounded in right hemispheric functions.

METHODS

Right-handed participants were asked in two experiments to nonverbally demonstrate how to move tachistoscopically presented (in the left or right visual hemifields) geometric objects of different rotations into an identical final position. Two independent blind raters evaluated the videotaped hand gestures employing the Neuropsychological Gesture (NEUROGES) Coding System.

RESULTS

Pantomime gestures increase in order to rotate gravitationally unstable objects whereas spatial relation presentation gestures increase when to nonverbally demonstrate a gravitationally stable object. Individuals preferred the right hand for pantomime gestures but the left hand for spatial relation presentation gestures.

DISCUSSION

Individuals increase their pantomime gestures to nonverbally depict motion particularly with the right hand, i.e. the left hemisphere. In contrast, increased left hand spatial relation presentations gestures indicate that those gestures are of right hemispheric origin. Thus, the hemispherical lateralization of nonverbal gestures seems to depend on the hands' functional depiction.

Nonverbal Semantics Test (NVST)-A Novel Diagnostic Tool to Assess Semantic Processing Deficits: Application to Persons with Aphasia after Cerebrovascular Accident

Assessment of semantic processing capacities often relies on verbal tasks which are, however, sensitive to impairments at several language processing levels. Especially for persons with aphasia there is a strong need for a tool that measures semantic processing skills independent of verbal abilities. Furthermore, in order to assess a patient’s potential for using alternative means of communication in cases of severe aphasia, semantic processing should be assessed in different nonverbal conditions. The Nonverbal Semantics Test (NVST) is a tool that captures semantic processing capacities through three tasks—Semantic Sorting, Drawing, and Pantomime. The main aim of the current study was to investigate the relationship between the NVST and measures of standard neurolinguistic assessment. Fifty-one persons with aphasia caused by left hemisphere brain damage were administered the NVST as well as the Aachen Aphasia Test (AAT). A principal component analysis (PCA) was conducted across all AAT and NVST subtests. The analysis resulted in a two-factor model that captured 69% of the variance of the original data, with all linguistic tasks loading high on one factor and the NVST subtests loading high on the other. These findings suggest that nonverbal tasks assessing semantic processing capacities should be administered alongside standard neurolinguistic aphasia tests.

The Role of Gesture in Communication and Cognition: Implications for Understanding and Treating Neurogenic Communication Disorders

When people talk, they gesture. Gesture is a fundamental component of language that contributes meaningful and unique information to a spoken message and reflects the speaker's underlying knowledge and experiences. Theoretical perspectives of speech and gesture propose that they share a common conceptual origin and have a tightly integrated relationship, overlapping in time, meaning, and function to enrich the communicative context. We review a robust literature from the field of psychology documenting the benefits of gesture for communication for both speakers and listeners, as well as its important cognitive functions for organizing spoken language, and facilitating problem-solving, learning, and memory. Despite this evidence, gesture has been relatively understudied in populations with neurogenic communication disorders. While few studies have examined the rehabilitative potential of gesture in these populations, others have ignored gesture entirely or even discouraged its use. We review the literature characterizing gesture production and its role in intervention for people with aphasia, as well as describe the much sparser literature on gesture in cognitive communication disorders including right hemisphere damage, traumatic brain injury, and Alzheimer's disease. The neuroanatomical and behavioral profiles of these patient populations provide a unique opportunity to test theories of the relationship of speech and gesture and advance our understanding of their neural correlates. This review highlights several gaps in the field of communication disorders which may serve as a bridge for applying the psychological literature of gesture to the study of language disorders. Such future work would benefit from considering theoretical perspectives of gesture and using more rigorous and quantitative empirical methods in its approaches. We discuss implications for leveraging gesture to explore its untapped potential in understanding and rehabilitating neurogenic communication disorders.

The relationship between co-speech gesture production and macrolinguistic discourse abilities in people with focal brain injury

Brain damage is associated with linguistic deficits and might alter co-speech gesture production. Gesture production after focal brain injury has been mainly investigated with respect to intrasentential rather than discourse-level linguistic processing. In this study, we examined 1) spontaneous gesture production patterns of people with left hemisphere damage (LHD) or right hemisphere damage (RHD) in a narrative setting, 2) the neural structures associated with deviations in spontaneous gesture production in these groups, and 3) the relationship between spontaneous gesture production and discourse level linguistic processes (narrative complexity and evaluation competence). Individuals with LHD or RHD (17 people in each group) and neurotypical controls (n = 13) narrated a story from a picture book. Results showed that increase in gesture production for LHD individuals was associated with less complex narratives and lesions of individuals who produced more gestures than neurotypical individuals overlapped in frontal-temporal structures and basal ganglia. Co-speech gesture production of RHD individuals positively correlated with their evaluation competence in narrative. Lesions of RHD individuals who produced more gestures overlapped in the superior temporal gyrus and the inferior parietal lobule. Overall, LHD individuals produced more gestures than neurotypical individuals. The groups did not differ in their use of different gesture forms except that LHD individuals produced more deictic gestures per utterance than RHD individuals and controls. Our findings are consistent with the hypothesis that co-speech gesture production interacts with macro-linguistic levels of discourse and this interaction is affected by the hemispheric lateralization of discourse abilities.

The relationship between handedness and valence: A gesture study

People with different hand preferences assign positive and negative emotions to different sides of their bodies and produce co-speech gestures with their dominant hand when the content is positive. In this study, we investigated this side preference by handedness in both gesture comprehension and production. Participants watched faceless gesture videos with negative and positive content on eye tracker and were asked to retell the stories after each video. Results indicated no difference in looking preferences regarding being right- or left-handed. Yet, an effect of emotional valence was observed. Participants spent more time looking to the right (actor's left) when the information was positive and to the left (actor's right) when the information was negative. Participants' retelling of stories revealed a handedness effect only for different types of gestures (representational vs beat). Individuals used their dominant hands for beat gestures. For representational gestures, while the right-handers used their right hands more, the left-handers gestured using both hands equally. Overall, the lack of significant difference between handedness and emotional content in both comprehension and production levels suggests that body-specific mental representations may not extend to the conversational level.

Effect of Stress Level on Different Forms of Self-Touch in Pre- and Postadolescent Girls

Self-touch serves for regulation of both hyper- and hypoarousal. It remains unclear if different forms of self-touch occur in different contexts, and if the regulatory mechanisms are learned or innate. The authors describe forms and context of self-touch, and explore age differences in stress processing. They analyzed hand movements of 10 pre- and 10 postadolescent girls in low-stress and high-stress settings and found 3 forms of self-touch. In postadolescent participants, self-touch 2 (irregular structure, rhythmical, medium intensity) and 3 (phasic structure, single accent, medium intensity) were used for self-regulation, whereas self-touch 1 (irregular structure, single accent, low intensity) had conversational reasons. Increasing immobility might represent the inward focus of stressed participants that tried to focus on the task. No differences were found for preadolescent participants. Differences between pre- and postadolescent participants might be due to brain development during adolescence.

Proximal and distal. Rethinking linguistic form and use for clinical purposes

With clinical purposes in mind, a review of the proximal/distal opposition is carried out in order to define a universal parameter of variability in semiotic procedures. By taking into consideration different-although notionally inter-related-senses of the proximal/distal opposition, a cluster of semiotic properties is proposed, which initially permits one to characterize dimensions of variability in the form and use of gestures. The subsequent and central aim of this paper is, however, to demonstrate that the same, or homologous, properties can also serve to characterize variability in the use of language, by assuming a basic connection between gesturing and linguistic behaviour. The main focus of interest and the starting point for reflections are communicative impairments as manifested in apraxia and aphasia.

Coding gestural behavior with the NEUROGES--ELAN system

We present a coding system combined with an annotation tool for the analysis of gestural behavior. The NEUROGES coding system consists of three modules that progress from gesture kinetics to gesture function. Grounded on empirical neuropsychological and psychological studies, the theoretical assumption behind NEUROGES is that its main kinetic and functional movement categories are differentially associated with specific cognitive, emotional, and interactive functions. ELAN is a free, multimodal annotation tool for digital audio and video media. It supports multileveled transcription and complies with such standards as XML and Unicode. ELAN allows gesture categories to be stored with associated vocabularies that are reusable by means of template files. The combination of the NEUROGES coding system and the annotation tool ELAN creates an effective tool for empirical research on gestural behavior.

Gesture and aphasia: Helping hands?

BACKGROUND: The study of communicative gestures is one of considerable interest for aphasia, in relation to theory, diagnosis, and treatment. Significant limitations currently permeate the general (psycho)linguistic literature on gesture production, and attention to these limitations is essential for both continued investigation and clinical application of gesture for people with aphasia. AIMS: The aims of this paper are to discuss issues imperative to advancing the gesture production literature and to provide specific suggestions for applying the material herein to studies in gesture production for people with aphasia. MAIN CONTRIBUTION: Two primary perspectives in the gesture production literature are distinct in their proposals about the function of gesture, and about where gesture arises in the communication stream. These two perspectives will be discussed, along with three elements considered to be prerequisites for advancing the research on gesture production. These include: operational definitions, coding systems, and the temporal synchrony characteristics of gesture. CONCLUSIONS: Addressing the specific elements discussed in this paper will provide essential information for both continued investigation and clinical application of gesture for people with aphasia.

Speech-independent production of communicative gestures: Evidence from patients with complete callosal disconnection

Recent neuropsychological, psycholinguistic, and evolutionary theories on language and gesture associate communicative gesture production exclusively with left hemisphere language production. An argument for this approach is the finding that right-handers with left hemisphere language dominance prefer the right hand for communicative gestures. However, several studies have reported distinct patterns of hand preferences for different gesture types, such as deictics, batons, or physiographs, and this calls for an alternative hypothesis. We investigated hand preference and gesture types in spontaneous gesticulation during three semi-standardized interviews of three right-handed patients and one left-handed patient with complete callosal disconnection, all with left hemisphere dominance for praxis. Three of them, with left hemisphere language dominance, exhibited a reliable left-hand preference for spontaneous communicative gestures despite their left hand agraphia and apraxia. The fourth patient, with presumed bihemispheric language representation, revealed a consistent right-hand preference for gestures. All four patients displayed batons, tosses, and shrugs more often with the left hand/shoulder, but exhibited a right hand preference for pantomime gestures. We conclude that the hand preference for certain gesture types cannot be predicted by hemispheric dominance for language or by handedness. We found distinct hand preferences for specific gesture types. This suggests a conceptual specificity of the left and right hand gestures. We propose that left hand gestures are related to specialized right hemisphere functions, such as prosody or emotion, and that they are generated independently of left hemisphere language production. Our findings challenge the traditional neuropsychological and psycholinguistic view on communicative gesture production.

Development of procedures for rating posed emotional expressions across facial, prosodic, and lexical channels

A number of rating systems are available to evaluate emotional communication in a single modality. The main purpose of this study was to develop procedures to train human raters to evaluate posed expressions of emotion across three different channels of communication, i.e., facial, prosodic/intonational, and lexical/verbal. These procedures were used to evaluate posed emotional expressions produced by individuals with unilateral brain lesions from stroke. Posers in this preliminary report were two right brain-damaged, two left brain-damaged, and two normal control right-handed adults who were matched on demographic and neurological factors. Eight emotional expressions, both positive and negative, were produced in three channels and rated for intensity, pleasantness, and category accuracy. 15 normal adults served as raters, five per channel. The rating procedures were comparable across channels, with analogous properties, and yielded substantial interrater agreement. In this small sample of posers, it was observed that the expressions of the right brain-damaged group were rated as the least accurate and those of the left brain-damaged group as the most intense. When patterns of individual performance across the channels were examined, performance was quiet consistent for the normal controls yet variable for the right brain-damaged persons. These observations are in keeping with the notion that patients with right hemisphere pathology have difficulty in emotional communication. In summary, these findings suggest that comparison of emotional expressions across multiple channels is feasible.