Recipient organisationNIHR Wellcome Trust Imperial Clinical Research Facility
NIHR supportRecorded as supported by this research centre
PeriodMar 2025 — Jul 2025
In plain English
AI plain-English summary
After a stroke, some people lose the ability to perform simple learned movements—like picking up a mug or making tea—even though their muscles are not paralysed. This condition, limb apraxia, is poorly understood and linked to worse recovery after stroke. Current rehabilitation often misses the mark because the underlying brain mechanisms are unclear. The researchers hypothesise that the core problem is not weakness, but an inability to select the correct action among competing possibilities—for example, choosing to grasp a cup by its handle rather than its rim. In the first phase, stroke patients and people with Parkinson’s disease will perform movements toward handheld objects while researchers measure their speed, accuracy, and movement patterns. The second phase uses brain imaging to identify which motor pathways are damaged in apraxia, comparing stroke patients with and without the condition. If successful, this work will reveal the specific neural circuits behind apraxia. That could lead to targeted therapies—for instance, retraining action selection rather than general motor skills—and improve functional recovery for stroke survivors. The research is fundamental science: it first aims to explain a poorly understood disorder before designing treatments.
View original technical description
Limb apraxia is a disorder in performing skilled/learnt movements often observed in patients after a stroke, but also in neurodegenerative diseases and movement disorders such as Parkinson's disease. Patients typically have problems with using everyday objects or sequencing actions as simple as making a cup of tea. Studies have shown that this condition is associated with worse functional recovery after a stroke. Despite implications on recovery - this condition is still poorly understood.We have obtained a BMA award which aims to understand the mechanisms underlying this disorder so as to target more appropriate therapies. We hypothesize that an important reason patients with apraxia have higher order motor deficits relates to an inability to select among competing actions. In an initial behavioural study, participants will be tested in conditions where they have to perform movements towards handheld objects. We will vary the familiarity of the action they have to perform by changing object characteristics (such as its position) and task instruction. We will measure their responses with quantitative methods (speed and accuracy of movement, as well as movement kinematics). We will compare any deficits obtained in patients with limb apraxia secondary to stroke versus those with Parkinson's disease. We hypothesise that deficits in action selection in those two groups would differ in this task. In the second phase of the study, we will use well established brain imaging techniques to identify the motor pathways which may be implicated in this disorder by comparing brain activations during such task performance, together with functional and structural connectivity measures of brain pathways in stroke patients with limb apraxia versus stroke patients without apraxia and healthy volunteers.
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