Virtual Reality Assessment of Arm Non-Use After Stroke

After a stroke, 80% of survivors show reduced use of the weaker arm during their activities of daily living. While conventional wisdom and previous research has attributed this reduced arm use to physical abilities (e.g., weakness) of the more affected arm, recent work is beginning to reveal a more complex and perplexing story. Research has uncovered a mismatch between the physical ability and actual use of the more affected arm in daily life, called arm non-use. In other words, some stroke survivors can do more with their weaker arm than they choose to do when given the option of which arm to use. Arm non-use is an urgent problem for stroke recovery because it suggests that improvements in the more affected arm during rehabilitation may not translate to improved use in daily life.

But why does arm non-use occur and what contributes to its severity? These questions are at the heart of new research by Cory Potts, PhD, Shailesh Kantak, PhD, PT, and Laurel Buxbaum, PsyD, at Moss Rehabilitation Research Institute. Specifically, they are interested in how psychological variables, like attentional demands, interact with arm non-use. Recently, they designed a new virtual reality (VR) reaching task to test whether use of the more affected arm decreases under more difficult, attention-demanding conditions. In the experiment, participants with stroke and healthy controls wore a VR headset and hand-held controllers that allowed them to interact with a virtual environment. They saw a virtual shelf with different objects and were asked to reach out with the hand of their choice and touch a target object (e.g., a pear) specified prior to each trial (Fig. 1). Researchers systematically varied the difficulty of the task in three different conditions. In the easy condition, the virtual objects were from different categories (produce, animals, household objects) so that the target object stood out (as shown in Fig 1). In the hard condition, the virtual objects were from the same category (i.e., all produce). In the third, most difficult condition, the participants had to multitask by responding to the sounds they heard while reaching and touching the target object in an array of other objects from the same category.

The results of this experiment have opened a new window into the interplay between cognition and physical action in stroke survivors. As task difficulty increased, participants with stroke were less likely to use their more affected arm, despite being able to reach with it. This suggests that more difficult, attention-demanding tasks may increase the severity of arm non-use in individuals with stroke. Interestingly, the demands on attention also affected how participants moved. Participants produced more curved, slower reaches under more demanding conditions, particularly when using their more affected arm. Though cognition and action are often thought as separate domains, our results show that the interaction of cognitive-motor processes affect the planning and performance of movements after stroke.

The research described here is just the beginning of a much larger project investigating the cognitive, physical, and neural factors contributing to arm non-use. Drs Potts, Kantak, and Buxbaum are currently working with their research team to develop an updated version of the virtual arm nonuse task. This version will use movement tracking to allow participants to freely grasp and pick up objects in the virtual environment and will also allow participants to receive feedback about their reaching performance. The broader goal of this experiment will be to investigate how reward and effort interact with the use of the more affected arm. Moreover, we hope that such a tool could be used as a quick assay of arm non-use in clinical settings to evaluate and potentially predict arm non-use. Rehabilitation strategies can then be targeted to remediate arm non-use in those identified through such a test. Through this project, we not only hope to build a clearer picture of the underpinnings of arm non-use but also develop clinical tools to improve diagnosis and treatments for this puzzling feature of motor disability.


Figure 1. Screenshot of the virtual reality reaching task. Participants’ hands appeared as gloves in the virtual display. The target object for this trial was the pear. The image shows the easier condition, where the objects on the shelf were from mixed categories (produce, animals, and household objects).

New Research by Scientists at MRRI and UCL Investigates the Impacts of Gesture on Naming Ability in People with Aphasia

Communication is more than just talking. In a face-to-face conversation, we also use gestures and facial expressions alongside speech to convey information. For example, the concept of waving your hand to greet someone can be expressed by saying the word “waving” or by performing the gesture itself. These concepts stored in long-term memory are thought to be shared across networks of brain areas responsible for speech and gesture. Gestures may also support word-finding: some studies have shown that when people struggle to retrieve words, producing a corresponding gesture also triggers production of the word. Other studies, however, have shown no effect of gesture on word-finding.

For individuals with aphasia, a language disorder that is common after a stroke or brain injury, word-finding difficulties are frequent. Because of this, some types of speech-language therapy encourage individuals with aphasia to rely on gesture to help them retrieve words more easily. However, an alternative approach known as constraint-induced language therapy requires individuals to rely on speech alone and restricts the use of gesture. While some individuals with aphasia benefit from constraint-induced language therapy, others benefit from therapy that allows for the use of gesture. It is unclear why different individuals with aphasia benefit from different types of therapy.

Approximately half of individuals with aphasia following a stroke also suffer from limb apraxia, a disorder which results in the impaired production of gestures and other skilled actions. One possibility is that individuals with limb apraxia will benefit less from the observation and use of gesture during speech-language therapy. To investigate this possibility, researchers from Moss Rehabilitation Research Institute (MRRI) and University College London (UCL) Amy Lebkuecher, PhD, Laurel Buxbaum, PsyD, Isobel Chick, MSc, and Gabriella Vigliocco, PhD, are conducting a study about the effect of gesture on naming ability in individuals with aphasia after stroke. In this experiment, the researchers are using gamified tasks, specifically “Go Fish” and “Heads Up”, to evaluate naming ability in an engaging and naturalistic context. Individuals with aphasia participating in this experiment are asked to complete these gamified tasks in two conditions: one that permits the use of gesture, and one that constrains it. In the condition where use of gesture is permitted, participants also observe the researcher performing gestures that are conceptually related to the objects and actions being named or described. In the condition where the use of gesture is constrained, both participant and researcher are not allowed to use gestures to communicate.

The researchers will compare participants’ performance on the gamified tasks across these conditions to determine whether the ability to name objects and actions improves when individuals with aphasia are allowed to use and observe meaningful, co-speech gestures. Additionally, the researchers will examine whether the benefit of gesture differs for individuals with and without limb apraxia, and explore whether there are other individual differences that affect whether gestures support word retrieval in aphasia. Data collection for this study is currently in progress. This research aims to advance our scientific understanding of the connection between speech and gesture in the brain. From a clinical perspective, the findings of this study may also help identify which individuals with aphasia are likely to benefit from the

use of gesture during speech-language therapy, potentially leading to more personalized therapy.

Interview with MRRI Postdoc Dr. Simon Thibault

Moss Rehabilitation Research Institute (MRRI) was pleased to welcome Simon Thibault, PhD, in January of 2022. Since joining the Institute, Dr. Thibault has been working with Institute Scientists Aaron Wong, PhD, and Laurel Buxbaum, PsyD, to further his training and his scientific research. In this interview, Dr. Thibault shares more about his career and his work.

1) Can you tell us more about your academic background and training?

I did my studies in France with my undergraduate and postgraduate degrees in Sports and Human Movement Sciences at the University of Nantes. In Nantes, I became interested in research quite early, and I was at that time mentored by Dr. Thibault Deschamps. Afterwards, I did a 5-month postgraduate internship at the University of Queensland in Australia in Dr. Timothy Carroll’s lab which focuses on exercise science and motor control. My early research projects were related to the interaction between cognition and the motor system, or more general motor control projects. After this internship, I started my PhD at the University of Lyon under the supervision of Dr. Claudio Brozzoli and Dr. Alice Roy. During my PhD, I continued investigating interactions between cognition and the motor system, particularly focusing on the interaction between tool-use and language. I started my postdoc at MRRI about one year ago under the supervision of Dr. Aaron Wong and Dr. Laurel Buxbaum, and my current research projects are examining tool-use impairments in patients with neurological conditions such as stroke.

2) What attracted you to science?

I think I find science attractive because you work at the edge of current knowledge, and you can participate in extending this knowledge. I think that is the thing that excites me the most about science. Also, I like the fact that it requires me to learn and master multiple skills for various tasks, such as creating a new project from scratch, setting up a new experiment, analyzing data, and then sharing these results with the community through conferences or journal papers. More specifically, I have been particularly attracted to neuroscience because the brain is an intriguing part of our body, in which the mechanisms for many functions are still unclear. It is definitely exciting to be part of the research community trying to disentangle how this structure works.

3) Why did you choose to work at MRRI?

MRRI has given me the opportunity to pursue my main research interest in tool-use and complex motor behaviors (and how these motor functions interact with the cognitive system) by studying patients with apraxia. Apraxia occurs after a left-hemisphere cerebrovascular accident, and it impacts the actions of daily life, the use of tools, and complex motor behavior without apparent low-level sensorimotor deficits. For me, this is also a real opportunity to learn about the neuropsychological approach from experts in the field.

4) What are some of the research questions you are currently working to address?

Currently, I am working on determining what makes tools difficult to use for patients with apraxia. Dr. Wong, Dr. Buxbaum, and I think the degree to which the hand motion and tool tip motion differ makes these tools difficult to use for these patients. In parallel, I am planning to lead a project to better understand what makes it difficult for stroke patients (with or without apraxia) to perform an action sequence.

5) What have been some of the key findings of your research thus far?

During my PhD, I demonstrated that that tool-use abilities and syntactic abilities in language involved similar parts of the brain, and they reciprocally influence each other at the behavioral level. This finding has been of interest for a large community of scientists but also therapists because it introduces questions regarding whether patient populations with language or motor impairment may recover function by training the non-impaired ability (either language or motor function).

6) Can you tell us more about the impact or potential impact of your research?

Despite several years of research, apraxia is still a poorly understood deficit, and there are a lot of debates about what is really impaired in these patients and what the underlying mechanisms are. I hope my work will help to better clarify the underlying mechanisms, which could result in the development of new rehabilitation strategies to help these patients to cope with the difficulties they experience in their daily lives.

7) What is something that you have learned or hope to learn during your postdoc at MRRI?

Starting my postdoc at MRRI has been exciting and informative on many levels. First, I needed to familiarize myself with this novel environment and a new country. MRRI has a great environment for training and performing neuropsychological research thanks to the MRRI Research Registry. It has been interesting to learn more about how research is funded and conducted in the United States. Also, I was glad to gain experience working with patients. There are many considerations when conducting research with patient populations, and it is very different from working with neurotypical participants. By coming here, I hope to learn new skills, especially in grant-writing, to become a more independent researcher, as well as to gain new skills in neuroimaging analyses of patients’ data.

8) What is one of your favorite MRRI memories?

I would say the inclusion of the first patient in my study was a stressful but an exciting moment. Given some patients may have some language impairments, it is an additional challenge to make sure they can understand me with my (strong) French accent. However, most of them have been able to understand my instructions so far, and there is always a research assistant around that can help me handle more complex situations. I also have to acknowledge that I was particularly well trained by my advisors before this first patient inclusion to avoid these potentials misunderstandings.

9) What are your long-term career goals?

I would like to get a permanent research position in academia. Most likely, I will return to France for my next position, but I am open to any other interesting opportunities that may arise.

10) What do you like to do in your free time?

I am a big fan of sports, especially basketball, so I am happy to live in the U.S. where basketball is popular. I like to go to the 76ers games, and I also try to keep playing basketball at least once each week. In addition, I spend a lot of time with a group of French expats that are now my friends.