Walking but not barking improves verb recovery: implications for action observation treatment in aphasia rehabilitation

What Else Can Be Done by the Spinal Cord? A Review on the Effectiveness of Transpinal Direct Current Stimulation (tsDCS) in Stroke Recovery

Since the spinal cord has traditionally been considered a bundle of long fibers connecting the brain to all parts of the body, the study of its role has long been limited to peripheral sensory and motor control. However, in recent years, new studies have challenged this view pointing to the spinal cord's involvement not only in the acquisition and maintenance of new motor skills but also in the modulation of motor and cognitive functions dependent on cortical motor regions. Indeed, several reports to date, which have combined neurophysiological techniques with transpinal direct current stimulation (tsDCS), have shown that tsDCS is effective in promoting local and cortical neuroplasticity changes in animals and humans through the activation of ascending corticospinal pathways that modulate the sensorimotor cortical networks. The aim of this paper is first to report the most prominent tsDCS studies on neuroplasticity and its influence at the cortical level. Then, a comprehensive review of tsDCS literature on motor improvement in animals and healthy subjects and on motor and cognitive recovery in post-stroke populations is presented. We believe that these findings might have an important impact in the future making tsDCS a potential suitable adjunctive approach for post-stroke recovery.

Point-light display: a new tool to improve verb recovery in patients with aphasia? A pilot study

Some studies have demonstrated that Action Observation (AO) could help patients with aphasia to recover use of verbs. However, the role of kinematics in this effect has remained unknown. The main aim was to assess the effectiveness of a complementary intervention based on the observation of action kinematics in patients with aphasia. Seven aphasic patients (3 males, 4 females) aged between 55 and 88 years participated in the studies. All patients received a classical intervention and an additional, specific intervention based on action observation. This consisted in visualizing a static image or a point-light sequence representing a human action and in trying to name the verb representing the action. In each session, 57 actions were visualized: 19 represented by a static drawing, 19 by a non-focalized point-light sequence, i.e., a point-light display with all dots in white, and 19 by a focalized point-light sequence, i.e., a point-light display (PLD) with the dots corresponding to the main limbs in yellow. Before (pre-test) and after (post-test) the intervention, each patient performed the same denomination task, in which all actions were presented in photographs. The results showed a significant improvement in performance between pre and post-test, but only when the actions were presented in focalized and non-focalized point-light sequences during the intervention. The presentation of action kinematics seems crucial in the recovery of verbs in patients with aphasia. This should be considered by speech therapists in their interventions.

Transcranial Direct-Current Stimulation and Behavioral Training, a Promising Tool for a Tailor-Made Post-stroke Aphasia Rehabilitation: A Review

Aphasia is an acquired language disorder resulting from damage to portions of the brain which are responsible for language comprehension and formulation. This disorder can involve different levels of language processing with impairments in both oral and written comprehension and production. Over the last years, different rehabilitation and therapeutic interventions have been developed, especially non-invasive brain stimulation (NIBS) techniques. One of the most used NIBS techniques in aphasia rehabilitation is the Transcranial Direct-Current Stimulation (tDCS). It has been proven to be effective in promoting a successful recovery both in the short and the long term after a brain injury. The main strength of tDCS is its feasibility associated with relatively minor side effects, if safely and properly administered. TDCS requires two electrodes, an anode and a cathode, which are generally placed on the scalp. The electrode montage can be either unipolar or bipolar. The main aim of this review is to give an overview of the state of the art of tDCS for the treatment of aphasia. The studies described included patients with different types of language impairments, especially with non-fluent aphasia and in several cases anomia. The effects of tDCS are variable and depend on several factors, such as electrode size and montage, duration of the stimulation, current density and characteristics of the brain tissue underneath the electrodes. Generally, tDCS has led to promising results in rehabilitating patients with acquired aphasia, especially if combined with different language and communication therapies. The selection of the appropriate approach depends on the patients treated and their impaired language function. When used in combination with treatments such as Speech and Language Therapy, Constraint Induced Aphasia Therapy or Intensive Action Treatment, tDCS has generally promoted a better recovery of the impaired functions. In addition to these rehabilitation protocols, Action Observation Therapy, such as IMITAF, appeared to contribute to the reduction of post-stroke anomia. The potential of combining such techniques with tDCS would would therefore be a possibility for further improvement, also providing the clinician with a new action and intervention tool. The association of a tDCS protocol with a dedicated rehabilitation training would favor a generalized long-term improvement of the different components of language.

Procedural Learning through Action Observation: Preliminary Evidence from Virtual Gardening Activity in Intellectual Disability

Intellectual disability (ID) compromises intellectual and adaptive functioning. People with an ID show difficulty with procedural skills, with loss of autonomy in daily life. From an embodiment perspective, observation of action promotes motor skill learning. Among promising technologies, virtual reality (VR) offers the possibility of engaging the sensorimotor system, thus, improving cognitive functions and adaptive capacities. Indeed, VR can be used as sensorimotor feedback, which enhances procedural learning. In the present study, fourteen subjects with an ID underwent progressive steps training combined with VR aimed at learning gardening procedures. All participants were trained twice a week for fourteen weeks (total 28 sessions). Participants were first recorded while sowing zucchini, then they were asked to observe a virtual video which showed the correct procedure. Next, they were presented with their previous recordings, and they were asked to pay attention and to comment on the errors made. At the end of the treatment, the results showed that all participants were able to correctly garden in a real environment. Interestingly, action observation facilitated, not only procedural skills, but also specific cognitive abilities. This evidence emphasizes, for the first time, that action observation combined with VR improves procedural learning in ID.

The role of mirror mechanism in the recovery, maintenance, and acquisition of motor abilities

While it is well documented that the motor system is more than a mere implementer of motor actions, the possible applications of its cognitive side are still under-exploited, often remaining as poorly organized evidence. Here, we will collect evidence showing the value of action observation treatment (AOT) in the recovery of impaired motor abilities for a vast number of clinical conditions, spanning from traumatological patients to brain injuries and neurodegenerative diseases. Alongside, we will discuss the use of AOT in the maintenance of appropriate motor behavior in subjects at risk for events with dramatic physical consequences, like fall prevention in elderly people or injury prevention in sports. Finally, we will report that AOT can help to tune existing motor competencies in fields requiring precise motor control. We will connect all these diverse dots into the neurophysiological scenario offered by decades of research on the human mirror mechanism, discussing the potentialities for individualization. Empowered by modern technologies, AOT can impact individuals' safety and quality of life across the whole lifespan.

Increased links between language and motor areas: A proof-of-concept study on resting-state functional connectivity following Personalized Observation, Execution and Mental imagery therapy in chronic aphasia

A tight coupling of language and motor processes has been established, which is consistent with embodied cognition theory. However, very few therapies have been designed to exploit the synergy between motor and language processes to help rehabilitate people with aphasia (PWA). Moreover, the underlying mechanisms supporting the efficacy of such approaches remain unknown. Previous work in our laboratory has demonstrated that personalized observation, execution, and mental imagery therapy (POEM)-a new therapy using three sensorimotor strategies to trigger action verb naming-leads to significant improvements in verb retrieval in PWA. Moreover, these improvements were supported by significant activations in language and sensorimotor processing areas, which further reinforce the role of both processes in language recovery (Durand et al., 2018). The present study investigates resting state functional connectivity (rsFC) changes following POEM in a pre-/post-POEM therapy design. A whole brain network functional connectivity approach was used to assess and describe changes in rsFC in a group of four PWA, who were matched and compared with four healthy controls (HC). Results showed increased rsFC in PWA within and between visuo-motor and language areas (right cuneal cortex-left supracalcarin (SCC) cortex/right precentral gyrus (PreCG)-left lingual gyrus (LG)) and between areas involved in action processing (right anterior parahippocampal gyrus (aPaHC)-left superior parietal lobule (SPL). In comparison to HC, the PWA group showed increased rsFC between the right inferior frontal gyrus (IFG) and left thalamus, which are areas involved in lexico-semantic processing. This proof-of-concept study suggests that the sensorimotor and language strategies used in POEM may induce modifications in large-scale networks, probably derived from the integration of visual and sensorimotor systems to sustain action naming, which is consistent with the embodied cognition theory.

Can Alzheimer's Disease Be Prevented? First Evidence from Spinal Stimulation Efficacy on Executive Functions

BACKGROUND

Recently, a growing body of evidence has shown that, from the early stage of impairment, Alzheimer's patients (AD) present difficulties on a variety of tasks mostly relying on executive functions. These strongly impact their daily life activities causing a severe loss of independency and autonomy.

OBJECTIVE

To evaluate the efficacy of transpinal direct current stimulation (tsDCS) combined with cognitive trainings for improving attentional and executive function abilities in a group of AD patients.

METHODS

In a randomized-double blind design, sixteen AD patients underwent different cognitive trainings combined with tsDCS. During the treatment, each subject received tsDCS (20 min, 2 mA) over the thoracic vertebrae (IX-X vertebrae) in two different conditions: 1) anodal, and 2) sham while performing three computerized tasks: alertness, selective attention, and executive functions. Each experimental condition was run in ten consecutive daily sessions over two weeks.

RESULTS

After anodal tsDCS, a greater improvement in executive functions compared to sham condition was found. More importantly, the follow-up testing revealed that these effects lasted over 1 month after the intervention and generalized to the different neuropsychological tests administered before, after the treatment and at one month after the end of the intervention. This generalization was present also in the attentional domain.

CONCLUSION

This evidence emphasizes, for the first time, that tsDCS combined with cognitive training results efficacious for AD patients. We hypothesize that enhancing activity into the spinal sensorimotor pathways through stimulation improved cognitive abilities which rely on premotor activity, such as attention and executive functions.

Conversational Therapy through Semi-Immersive Virtual Reality Environments for Language Recovery and Psychological Well-Being in Post Stroke Aphasia

Aphasia is a highly disabling acquired language disorder generally caused by a left-lateralized brain damage. Even if traditional therapies have been shown to induce an adequate clinical improvement, a large percentage of patients are left with some degree of language impairments. Therefore, new approaches to common speech therapies are urgently needed in order to maximize the recovery from aphasia. The recent application of virtual reality (VR) to aphasia rehabilitation has already evidenced its usefulness in promoting a more pragmatically oriented treatment than conventional therapies (CT). In the present study, thirty-six chronic persons with aphasia (PWA) were randomly assigned to two groups. The VR group underwent conversational therapy during VR everyday life setting observation, while the control group was trained in a conventional setting without VR support. All patients were extensively tested through a neuropsychological battery which included not only measures for language skills and communication efficacy but also self-esteem and quality of life questionnairies. All patients were trained through a conversational approach by a speech therapist twice a week for six months (total 48 sessions). After the treatment, no significant differences among groups were found in the different measures. However, the amount of improvement in the different areas was distributed over far more cognitive and psychological aspects in the VR group than in the control group. Indeed, the within-group comparisons showed a significant enhancement in different language tasks (i.e., oral comprehension, repetition, and written language) only in the VR group. Significant gains, after the treatment, were also found, in the VR group, in different psychological dimensions (i.e., self-esteem and emotional and mood state). Given the importance of these aspects for aphasia recovery, we believe that our results add to previous evidence which points to the ecological validity and feasibility of VR treatment for language recovery and psychosocial well-being.

A Systematically Conducted Scoping Review of the Evidence and Fidelity of Treatments for Verb Deficits in Aphasia: Verb-in-Isolation Treatments

Purpose Aphasia research demonstrates increasing interest in the treatment of verb retrieval deficits. This systematically conducted scoping review reports on the level and fidelity of the current evidence for verb treatments; on its effectiveness regarding the production of trained and untrained verbs, functional communication, sentences, and discourse; and on the potential active ingredients. Recommendations to guide clinical decision making and future research are made. Method The computerized database search included studies from January 1980 to September 2018. The level of evidence of each study was documented, as was fidelity in terms of treatment delivery, enactment, and receipt. Studies were also categorized according to the treatment methods used. Results Thirty-seven studies were accepted into the review, and all but 1 constituted a low level of evidence. Thirty-three studies (89%) described treatment in sufficient detail to allow replication, dosage was poorly reported, and the fidelity of treatment was rarely assessed. The most commonly reported treatment techniques were phonological and semantic cueing in 25 (67.5%) and 20 (54%) studies, respectively. Retrieval of trained verbs improved for 80% of participants, and improvements generalized to untrained verbs for 15% of participants. There was not sufficient detail to evaluate the impact of treatment on sentence production, functional communication, and discourse. Conclusions The evidence for verb treatments is predominantly of a low level. There are encouraging findings in terms of treatments being replicable; however, this is tempered by poor monitoring of treatment fidelity. The quality of verb treatment research would be improved by researchers reaching consensus regarding outcome measures (including generalization to, e.g., sentences and discourse) by manualizing treatment to facilitate implementation and exploring the opinions of participants. Finally, while treatment is largely effective in improving production of trained verbs, lack of generalization to untrained items leads to the recommendation that personally relevant verbs are prioritized.

Looking at ancillary systems for verb recovery: Evidence from non-invasive brain stimulation

Several behavioural and neuroimaging studies have suggested that the language function is not restricted into the left areas but it involves regions not predicted by the classical language model. Accordingly, the Embodied Cognition theory postulates a close interaction between the language and the motor system. Indeed, it has been shown that non-invasive brain stimulation (NIBS) is effective for language recovery also when applied over sensorimotor regions, such as the motor cortex, the cerebellum and the spinal cord. We will review a series of NIBS studies in post-stroke aphasic people aimed to assess the impact of NIBS on verb recovery. We first present results which, following the classical assumption of the Broca's area as the key region for verb processing, have shown that the modulation over this area is efficacious for verb improvement. Then, we will present experiments which, according to Embodied Cognition, have directly investigated through NIBS the role of different sensorimotor regions in enhancing verb production. Since verbs play a crucial role for sentence construction which are most often impaired in the aphasic population, we believe that these results have important clinical implications. Indeed, they address the possibility that different structures might support verb processing.

Physical and observational practices of unusual actions prime action verb processing

Numerous studies have highlighted a strong relationship between language and sensorimotor processes, showing, for example, that perceiving an action influences subsequent language processing. Moreover, previous studies have demonstrated that the context in which actions are perceived is crucial to enable this action-language relationship. In particular, action verb processing is facilitated when an action is perceived in its usual context (e.g., someone watering a plant) but not in an unusual context (e.g., someone watering a computer). This difference could be explained in terms of experience; because people always practice actions in accordance with the context, they have no (visual or motor) experience related to the unusual context. The aim of the present study was to test this assumption by assessing and comparing the effect of physical practice and observational learning on the action-language relationship. The results of two experiments showed a facilitation effect of both training methods. Whereas usual actions systematically prime action verb processing, the link between action and language appears for unusual actions only after training by practicing (experiment 1, physical practice) or observing (experiment 2, observational learning). Overall, these findings support the role of experience in the activation of sensorimotor representations during action verb processing.

Poststroke Aphasia Rehabilitation: Why All Talk and No Action?

There is ample agreement in the scientific literature, across diverse areas of study, that suggests that language and movement are interrelated. In particular, it is widely held that the upper limb and hand play a key role in language use. Aphasia, a common, disabling language disorder frequently associated with stroke, requires new restorative methods. A combinatorial hand-arm-language paradigm that capitalizes on shared neural networks may therefore prove beneficial for aphasia recovery in stroke patients and requires further exploration.

Time-Frequency Analysis of Mu Rhythm Activity during Picture and Video Action Naming Tasks

This study used whole-head 64 channel electroencephalography to measure changes in sensorimotor activity—as indexed by the mu rhythm—in neurologically-healthy adults, during subvocal confrontation naming tasks. Independent component analyses revealed sensorimotor mu component clusters in the right and left hemispheres. Event related spectral perturbation analyses indicated significantly stronger patterns of mu rhythm activity (pFDR < 0.05) during the video condition as compared to the picture condition, specifically in the left hemisphere. Mu activity is hypothesized to reflect typical patterns of sensorimotor activation during action verb naming tasks. These results support further investigation into sensorimotor cortical activity during action verb naming in clinical populations.

Treatment of verb anomia in aphasia: efficacy of self-administered therapy using a smart tablet

Aphasia is a chronic condition that usually requires long-term rehabilitation. However, even if many effective treatments can be offered to patients and families, speech therapy services for individuals with aphasia often remain limited because of logistical and financial considerations, especially more than 6 months after stroke. Therefore, the need to develop tools to maximize rehabilitation potential is unquestionable. The aim of this study was to test the efficacy of a self-administered treatment delivered with a smart tablet to improve written verb naming skills in CP, a 63-year-old woman with chronic aphasia. An ABA multiple baseline design was used to compare CP's performance in verb naming on three equivalent lists of stimuli trained with a hierarchy of cues, trained with no cues, and not trained. Results suggest that graphemic cueing therapy, done four times a week for 3 weeks, led to better written verb naming compared to baseline and to the untrained list. Moreover, generalization of the effects of treatment was observed in verb production, assessed with a noun-to-verb production task. Results of this study suggest that self-administered training with a smart tablet is effective in improving naming skills in chronic aphasia. Future studies are needed to confirm the effectiveness of new technologies in self-administered treatment of acquired language deficits.

Enhanced Neurobehavioral Outcomes of Action Observation Prosthesis Training

Background Previous studies have demonstrated improved neurobehavioral outcomes when prosthesis users learn task-specific behaviors by imitating movements of prosthesis users (matched limb) compared with intact limbs (mismatched limb). Objective This study is the first to use a unique combination of neurophysiological and task performance methods to investigate prosthetic device training strategies from a cognitive motor control perspective. Intact nonamputated prosthesis users (NAPUs) donned specially adapted prosthetic devices to simulate the wrist and forearm movement that persons with transradial limb loss experience. The hypothesis is that NAPUs trained with matched limb imitation would show greater engagement of parietofrontal regions and reduced movement variability compared with their counterparts trained with a mismatched limb. Methods Training elapsed over 3 days comprised alternating periods of video demonstration observation followed by action imitation. At the beginning and end of the training protocol, participants performed a cued movement paradigm while electroencephalography and electrogoniometry data were collected to track changes in cortical activity and movement variability, respectively. Results Matched limb participants showed greater engagement of motor-related areas while mismatched limb participants showed greater engagement of the parietooccipital system. Matched limb participants also showed lower movement variability. Conclusions These results indicate that the type of limb imitated influences neural and behavioral strategies for novel prosthetic device usage. This finding is important, as customary prosthetic rehabilitation with intact therapists involves mismatched limb imitation that may exacerbate challenges in adapting to new motor patterns demanded by prosthesis use.

Mirror neuron therapy for hemispatial neglect patients

Mirror neuron system(MNS) based therapy has been employed to treat stroke induced movement disorders. However, its potential effects on patients with hemispatial neglect were uninvestigated. The present study set out to test the therapeutic efficiency of video watching of series of hand actions/movements (protocol A) in two patients with left hemispatial neglect, due to the right hemisphere stroke. The video containing dynamic landscape of natural scene or cities but not human/animals was used as the protocol B. The "ABA" training procedure for 3 weeks therefore allows us to internally control the individual differences. Before and after each week of training, the Chinese behavioral inattention test- Hongkong version (CBIT-HK) was implemented to evaluate the hemispatial neglect severity. Functional magnetic resonance imaging (fMRI) experiment was implemented in two health subjects to reveal the difference of brain activation between protocol A and B. The results showed that protocol A rather than protocol B significantly improved the CBIT-HK scores at first and third weeks, respectively. Protocol A induced more bilateral activations including right inferior parietal lobe (supramarginal gyrus), which belongs to MNS and is also critical region resulting to hemineglect.

CONCLUSION

MNS activation can provide a novel therapy for hemispatial neglect patients.

The contrast between cueing and/or observation in therapy for verb retrieval in post-stroke aphasia

BACKGROUND

Studies measuring treatment efficacy for post-stroke verb anomia are scarce. These studies mainly assessed the efficacy of three strategies: semantic, phonological and sensorimotor. Following these previous treatments, the performance of most participants improved on treated verbs, while improvement on untreated stimuli and tasks was inconsistent.

AIMS

This study aimed to measure the effectiveness of a semantic-phonological strategy and a sensorimotor strategy for verb anomia in post-stroke aphasia.

METHODS

A multiple baseline single-subject experimental study was conducted with two participants (9-37 years post-stroke). Four phases were completed: (1) background assessment, (2) baselines, (3) therapy, and (4) follow-up. Three equivalent lists of verbs were created for each participant and two of them were trained with a different strategy: action observation+semantic-phonological cues, action observation alone. The stimuli of the third list (control list) were not treated.

RESULTS

The semantic-phonological cueing strategy led to a significant improvement. No improvement was observed after action observation. No generalization to untreated verbs was found.

CONCLUSIONS

Verb naming can be enhanced by semantic/phonological cueing. In addition, other studies (clinical, neuroimaging, etc.) are needed to document the effect of action observation for the treatment of verb anomia.

LEARNING OUTCOMES

The reader will be able to (1) describe semantic-phonological therapies used in post-stroke verb anomia, (2) describe sensorimotor therapies used in post-stroke verb anomia, and (3) identify factors contributing to the efficacy of therapies to improve action naming in aphasia.

Improving verb anomia in the semantic variant of primary progressive aphasia: the effectiveness of a semantic-phonological cueing treatment

The semantic variant of primary progressive aphasia (svPPA) is known to affect the comprehension and production of all content words, including verbs. However, studies of the treatment of anomia in this disorder focused on relearning object names only. This study reports treatment of verb anomia in an individual with svPPA. The semantic-phonological cueing therapy resulted in significant improvement in naming abilities, for treated verbs only. This case study demonstrates that improvement in verb-naming abilities may be possible in svPPA. The almost complete maintenance of the treatment's effects in the patient 4 weeks after the end of the therapy also suggests improvements may be durable, at least in the short term, for some individuals with svPPA.

Are judgments for action verbs and point-light human actions equivalent?

The aim of the present study was to examine whether the ability to judge action words and the ability to judge human actions share common mechanisms. With this purpose in mind, we proposed both a lexical and an action decision task to twenty-four healthy participants. For both tasks, the participants had to judge whether the stimulus that was presented (a letter string or a point-light sequence) was valid or not (i.e. a word vs. a pseudo-word, an action vs. a pseudo-action). The data analysis showed that the action decision task has common characteristics with the lexical decision task. As for verbal material, judgements of pseudo-actions were slower than judgements for actions. Moreover, we demonstrated that the ability to judge an action verb was positively correlated with the ability to judge a point-light human action, whereas no significant correlation appeared between nouns and point-light judgements abilities. This dissociation supports the argument that the judgement of action words and the judgement of human actions share a common but specific basis through the involvement of motor representations.

Options to enhance recovery from aphasia by means of non-invasive brain stimulation and action observation therapy

Aphasia is a highly disabling language disorder usually caused by a left-lateralized brain damage. Even if traditional linguistic-based therapies have been proved to induce an adequate clinical improvement, a large percentage of patients are left with some degree of language impairments. Therefore, new approaches to common speech therapies are urgently needed in order to maximize the recovery from aphasia. The recent application of non-invasive neurostimulation techniques to language rehabilitation has already provided promising results particularly for the recovery of word-retrieval deficits in chronic stroke aphasic patients. Positive outcomes also come from action observation therapy. Indeed, some very recent studies have shown that the observation and/or execution of gestures positively influences language recovery especially for words related to human actions. This article gives an overview of the most important results achieved using these two approaches and discusses how the application of these treatments might potentiate aphasia recovery.