Task Specific Practice in Neurorehabilitation Darcy Reisman, PhD, PT Associate Professor Physical Therapy Biomechanics & Movement Science University of Delaware

Task-specific practice/training repetitive practice of a task that is specific to the intended outcome (Sullivan et al, 2007). systematic and repetitive practice of functional tasks (Winstein et al, 2004)

Why is task specific practice important in neurorehabilitation? Neuroplasticity Motor learning

…cells that fire together wire together… Kandel, Schwartz & Jessell, Principles of Neural Science, 2000

Principle 3: Specificity Matters Based on the article by Kleim and Jones, 2008 Principle 3: Specificity Matters Changes in specific brain areas occur relative to the task that is practiced Skilled practice results in changes in neural connectivity

Squirrel monkeys trained to retrieve pellets from the smallest well possible for 30 min for at least 11 days or until the number of daily retrievals was greater than 600 for 2 consecutive days showed substantial changes in their digit representations. Nudo et al, 1996

Skilled practice results in changes in neural connectivity Rats that learned to reach onto a rotating platform for pellets displayed more distal changes in their motor maps compared to rats who learned to press a bar. Kleim et al, 1998

Why is task specific practice important in neurorehabilitation? Neuroplasticity Motor learning

Motor Schema Theory (R. Schmidt, 1975, 2003) Subjects learn a schema or rule (algorithm) for producing an action. Learning the rule requires practice under a range of task conditions or environmental constraints. Once learned and practiced under a sufficient range of conditions, the rule can be used to extrapolate performance to a broader range of conditions or constraints not previously encountered.

Lashley (1942) classic study blindfolded subjects wrote words with their dominant hand, nondominant hand, and foot. The similarity of the individual’s handwriting characteristics under the different conditions and with different effectors was remarkable supported the argument that the representation that underlies handwriting skill was abstract—not stored in memory as a representation that was connected with neural commands to specific effectors.

Keetch et al (2005) Skilled basketball players produce set shots from a variety of locations. Greater percent success from the foul shot location, suggesting that massive amounts of practice from this location result in greater skill at this specific task.

Summary Data from animals and healthy humans suggests that specificity of training is important for neuroplasticity and motor learning

How does this apply to persons with neurological injury or disease? How specific should the practice be? Does my patient have to practice each specific task they need to accomplish? What about other important features of practice?

Task specific training How specific is specific enough? Shah et al 2012 Trained 20 spinal rats walking on the treadmill in either forward, sideways or backward directions over 28 sessions Tested walking in forward direction on treadmill Edee – I think these 3 slides would follow your slides discussing TM vs OG walking and transplant with UE vs LE training.

Rats trained in backward and sideways direction had greater step consistency and coordination and greater muscle activity during forward walking

Schaefer et al., 2013 Trained 11 persons with chronic stroke on a simulated feeding task over 5 days with 50 trials of practice/day

Tested for improvements on feeding task and on buttoning and sorting task Improvements observed on both the trained and non-trained tasks

Sullivan et al., 2007 Trained 80 persons with chronic stroke in 4 groups The resisted cycling program incorporated some of the weight-bearing and task-related demands of walking including cyclical activation of flexor and extensor muscles in a locomotor like pattern. Are similar improvements in walking speed observed between the 2 tasks?

4 one hour sessions/week for 6 weeks (24 sessions) BWSTT - 5 min bouts at 1.5-2.0 mph for total of 20 minutes of walking in the one hour session CYCLE - Loaded limb resisted cycling on Biodex semi-recumbent bike. 10 sets of 15 to 20 revolutions in each session. At least 2 minutes to rest between sets

 bwstt/ue-ex  cycle/ue-ex

Winstein et al, 1989 21 post-acute persons with stroke received standing balance training to improve asymmetry over a 3-4 week period. All subjects improved static standing asymmetry but did not improve asymmetry in walking after stroke

Summary Data suggests that when tasks share important key features, practice on one task will “transfer” to the other. Postural requirements critical?

Other important principles for neuroplasticity and motor learning

Principle 4: Repetition Matters Repetition of new task required to see neural changes Changes at the neuronal level not observed until significant repetition of new task, even when behavioral improvements observed Kleim & Jones, 2008

and 10 days, even though map changes continued. Rats trained in skilled reaching showed improved accuracy at 3, 7, 10 days of training. No difference in accuracy between 7 and 10 days, even though map changes continued. Kleim et al, 2004

Amount of practice is the single MOST important variable affecting motor learning (Schmidt & Lee, 2011) Ericsson et al, 1993

Baker and Cote, 2003

Principle 5: Intensity Matters (Kleim & Jones, 2008) High intensity stimulation = long-term potentiation Low intensity stimulation = long-term depression 1800 stimuli of 5 Hz transcranial magnetic stimulation, but not 150 stimuli, can induce a long-lasting and muscle-specific increase in resting corticospinal excitability (Peinemann et al, 2004). Need to differentiate between intensity and repetition

Intensity and repetition are as important as task specificity Yang et al, 2012 Trained 20 persons with chronic spinal cord injury on obstacle walking vs. BWSTT for speed and endurance Primary outcome: SCI-FAP - (7 tasks: (1) Carpet, (2) Up & Go, (3) Obstacles, (4) Stairs, (5) Carry, (6)Step, and (7) Door). Hypothesis was that task-specific over ground obstacle course training would result in greater improvements.

High specificity, but low intensity and limited repetition = less improvement

Duncan et al, 2011 LEAPS trial Randomized 408 sub-acute stroke survivors into 3 groups: early locomotor training, late locomotor training or home based PT. Average HR in locomotor training groups was 90 bpm and in home therapy group was 77 bpm

Variability, challenge and errors are critical aspects of task specific practice. Without these components, benefits of task-specific practice are reduced. Assist as needed robotic locomotor training is superior to standard robotic training providing full assistance in animal models of SCI…. Ziegler et al, 2010; Lee et al, 2011

…and in persons with chronic stroke (Krishnan et al, 2013) Full assist assist as needed

The opportunity to make and correct errors is important for learning Error augmented practice may be superior to repetitive task practice alone in those with chronic stroke (Reisman et al, 2013)

Summary Repetition, intensity and variability (opportunities to make and correct errors) are just as important as task specificity of practice and should be considered when designing neurorehabilitation interventions

How can I apply these principles in my patients with neurological injury/disease?

One major goal of PT is to return patients to their previous level of function and community participation

Recovery: return to, or emergence of, a desired level of function as viewed from the perspective of the patient and family What does the patient want/need to do that they currently cannot do Set goals relative to these activities and then….

PREPARE Preparation is key Identify all aspects of the desired activity

Need variety of objects

Need variety of contexts – total trips into community after stroke predicted by postural transitions and temporal characteristics (Robinson et al, 2013)

Need appropriate assistance

Need to increase intensity

Practice specific to goals, increase challenge and variability

Summary Task specific training of sufficient intensity and repetition is important following neurological injury/disease in order to optimize neuroplasticity and motor learning. Tasks trained need to share general characteristics with desired task

References