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Neural correlates of motor recovery after stroke: a longitudinal fMRI study
N S Ward1, M M Brown, A J Thompson
1Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London, UK. n.ward@fil.ion.ucl.ac.uk
Abstract:
Recovery of motor function after stroke may occur over weeks or months and is often attributed to cerebral reorganization. We have investigated the longitudinal relationship between recovery after stroke and task-related brain activation during a motor task as measured using functional MRI (fMRI). Eight first-ever stroke patients presenting with hemiparesis resulting from cerebral infarction sparing the primary motor cortex, and four control subjects were recruited. Subjects were scanned on a number of occasions whilst performing an isometric dynamic visually paced hand grip task. Recovery in the patient group was assessed using a battery of outcome measures at each time point. Task-related brain activations decreased over sessions as a function of recovery in a number of primary and non-primary motor regions in all patients, but no session effects were seen in the controls. Furthermore, consistent decreases across sessions correlating with recovery were seen across the whole patient group independent of rate of recovery or initial severity, in primary motor cortex, premotor and prefrontal cortex, supplementary motor areas, cingulate sulcus, temporal lobe, striate cortex, cerebellum, thalamus and basal ganglia. Although recovery-related increases were seen in different brain regions in four patients, there were no consistent effects across the group. These results further our understanding of the recovery process by demonstrating for the first time a clear temporal relationship between recovery and task-related activation of the motor system after stroke.
Insights
Brain activity in motor regions decreases over time as motor function recovers after stroke. This study shows a clear temporal link between brain activation changes and motor recovery in stroke patients.
Area of Science:
- Neuroscience
- Rehabilitation Medicine
- Medical Imaging
Background:
- Stroke often leads to motor deficits, with recovery influenced by cerebral reorganization over weeks to months.
- Understanding the neural mechanisms underlying motor recovery is crucial for developing effective rehabilitation strategies.
Purpose of the Study:
- To investigate the longitudinal relationship between motor function recovery after stroke and task-related brain activation using functional MRI (fMRI).
- To identify specific brain regions and patterns of activation changes associated with motor recovery.
Main Methods:
- Functional MRI (fMRI) was used to measure task-related brain activation during a hand grip task in eight stroke patients and four controls.
- Patients underwent multiple scanning sessions over time, with motor function assessed using outcome measures at each session.
- Analysis focused on changes in brain activation patterns longitudinally and their correlation with motor recovery.
Main Results:
- Task-related brain activations decreased over time in primary and non-primary motor regions in stroke patients, correlating with motor recovery.
- Consistent decreases in activation were observed across multiple brain areas, including the motor cortex, prefrontal cortex, cerebellum, and basal ganglia, irrespective of recovery rate or initial severity.
- No significant session-related changes in brain activation were observed in control subjects.
Conclusions:
- Demonstrates a clear temporal relationship between decreasing task-related brain activation and motor function recovery post-stroke.
- Suggests that changes in motor system activation patterns are a key component of the stroke recovery process.
- Provides insights into the neural dynamics of motor relearning and recovery after cerebral infarction.