Investigating Consolidation of Motor Learning in the Context of Recovery After Stroke

Rehabilitation of movement after stroke depends on motor learning. Motor learning involves not only improvement during practice but also improvement between sessions, known as consolidation of learning. Consolidation of learning depends on good sleep quality. However, there is growing evidence that sleep is disrupted after stroke, and it was recently shown that patients with poorer sleep show slower recovery of function and worse motor outcomes. This might occur because sleep disruption impairs consolidation directly or might reflect other factors that influence both sleep and clinical outcomes. This study aims to test whether the relationship between sleep disruption and clinical outcomes after stroke depends on consolidation of motor learning.

In people with stroke affecting the upper limb, the investigators will (1) test whether sleep measures in the sub-acute phase explains variation in clinical motor outcomes, taking into account recovery potential (as per the PREP2 algorithm(Predict REcovery Potential; www.presto.auckland.ac.nz)), demographic factors (age and sex) and other covariates as required (e.g. stroke severity, presence of sleep disorders, mood, physical activity), and (2) test whether this relationship is mediated by variation in behavioural measures of overnight motor consolidation.

The design is a longitudinal observational study. Participants will be recruited within 1 month of stroke onset from stroke wards. At baseline (≤ 1 month post-stroke), the investigators will use the PREP2 algorithm (www.presto.auckland.ac.nz) to ascertain expected upper limb recovery potential. This involves an assessment of arm movement and, for some participants, Transcranial Magnetic Stimulation to assess corticospinal tract integrity. The investigators will also record participant demographics, stroke severity (National Institute for Health Stroke Scale; NIHSS), and medications.

At approximately 1 month post-stroke the investigators will obtain sleep measures (actigraphy, electroencephalography, and questionnaires), assess mood (questionnaire) and test for motor consolidation (using an upper limb motor learning task). The investigators will also record medications, stroke severity (modified Rankin Scale questionnaire), and assess the possible presence of sleep disorders (sleep screening questionnaires), physical activity (actigraphy). The investigators will collect information about how much, if any, motor rehabilitation and sleep therapy the participants have received (questionnaire).

At 6 months post-stroke the investigators will obtain sleep measures (actigraphy, and questionnaire) and assess motor outcomes (upper limb ability, whole body motor impairment, hand dexterity, and mobility). The investigators will also record medications and assess mood (questionnaire), stroke severity (modified Rankin Scale questionnaire), physical activity (actigraphy), and information about how much, if any, motor rehabilitation and sleep therapy the participants have had (questionnaire).