From gestures to words: spontaneous verbal labeling of complex sequential hand movements reduces fMRI activation of the imitation-related regions

Language and gesture neural correlates: A meta-analysis of functional magnetic resonance imaging studies

BACKGROUND

Humans often use co-speech gestures to promote effective communication. Attention has been paid to the cortical areas engaged in the processing of co-speech gestures.

AIMS

To investigate the neural network underpinned in the processing of co-speech gestures and to observe whether there is a relationship between areas involved in language and gesture processing.

METHODS & PROCEDURES

We planned to include studies with neurotypical and/or stroke participants who underwent a bimodal task (i.e., processing of co-speech gestures with relative speech) and a unimodal task (i.e., speech or gesture alone) during a functional magnetic resonance imaging (fMRI) session. After a database search, abstract and full-text screening were conducted. Qualitative and quantitative data were extracted, and a meta-analysis was performed with the software GingerALE 3.0.2, performing contrast analyses of uni- and bimodal tasks.

MAIN CONTRIBUTION

The database search produced 1024 records. After the screening process, 27 studies were included in the review. Data from 15 studies were quantitatively analysed through meta-analysis. Meta-analysis found three clusters with a significant activation of the left middle frontal gyrus and inferior frontal gyrus, and bilateral middle occipital gyrus and inferior temporal gyrus.

CONCLUSIONS

There is a close link at the neural level for the semantic processing of auditory and visual information during communication. These findings encourage the integration of the use of co-speech gestures during aphasia treatment as a strategy to foster the possibility to communicate effectively for people with aphasia.

WHAT THIS PAPER ADDS

What is already known on this subject Gestures are an integral part of human communication, and they may have a relationship at neural level with speech processing. What this paper adds to the existing knowledge During processing of bi- and unimodal communication, areas related to semantic processing and multimodal processing are activated, suggesting that there is a close link between co-speech gestures and spoken language at a neural level. What are the potential or actual clinical implications of this work? Knowledge of the functions related to gesture and speech processing neural networks will allow for the adoption of model-based neurorehabilitation programs to foster recovery from aphasia by strengthening the specific functions of these brain networks.

Upper Limb Apraxia

PURPOSE OF REVIEW

Limb apraxia is one of the most common and most disabling disorders caused by brain damage. However, apraxia is one of the least recognized disorders associated with cerebral disease. This article discusses the signs and symptoms of, means of testing for, the pathophysiology of, and possible management of upper limb apraxia.

RECENT FINDINGS

Upper limb apraxia has four major forms: ideomotor, limb-kinetic, conceptual, and ideational. Although recent findings are included in this article, a full understanding of these disorders, including the means of testing, their possible pathophysiology, and the diseases that may cause these disorders, requires that some older literature is also discussed.

SUMMARY

This article guides clinicians in testing for and diagnosing the different forms of upper limb apraxia, identifying the underlying diseases that may cause apraxia, managing the different forms of the disorder, and possible forms of rehabilitation.

In which case is working memory for movements affected by verbal interference? Evidence from the verbal description of movement

Current perspectives on whether verbal interference affects working memory for movements have not yet reached a consensus. This study explored the causes of this controversy to reveal the relation between working memory for movements and the phonological loop. Experiment 1 explored whether the verbal description of movement moderated the effect of verbal interference (articulatory suppression) on working memory for movements. Verbal interference only affected working memory for easy-to-describe movements (lower accuracy). Experiment 2 excluded the interpretation of familiarity to the controversy and the effect of familiarity on the results of Experiment 1. Experiment 3 verified the results of Experiment 1 with another form of verbal interference, i.e., presenting irrelevant words visually. These three experiments suggest that the phonological loop is not recruited for processing working memory for movements in nature, but the two may interact through the verbal description prestored in the long-term memory. Thus, the current study provides a certain level of support for the separable movement-based subsystem hypothesis (Smyth, M. M., Pearson, N. A., & Pendleton, L. R. (1988). Movement and working memory: Patterns and positions in space. The Quarterly Journal of Experimental Psychology Section A: Human Experimental Psychology, 40(3), 497-514. doi:10.1080/02724988843000041).

What is the best strategy for retaining gestures in working memory?

This study aimed to determine whether the recall of gestures in working memory could be enhanced by verbal or gestural strategies. We also attempted to examine whether these strategies could help resist verbal or gestural interference. Fifty-four participants were divided into three groups according to the content of the training session. This included a control group, a verbal strategy group (where gestures were associated with labels) and a gestural strategy group (where participants repeated gestures and were told to imagine reproducing the movements). During the experiment, the participants had to reproduce a series of gestures under three conditions: "no interference", gestural interference (gestural suppression) and verbal interference (articulatory suppression). The results showed that task performance was enhanced in the verbal strategy group, but there was no significant difference between the gestural strategy and control groups. Moreover, compared to the "no interference" condition, performance decreased in the presence of gestural interference, except within the verbal strategy group. Finally, verbal interference hindered performance in all groups. The discussion focuses on the use of labels to recall gestures and differentiates the induced strategies from self-initiated strategies.