Bridging the Gap: Why neuroplasticity matters
In the Bridging the Gap series we are making comparisons between strategies and ideas used in training for elite sport and seeing if they are relevant to rehabilitation. In this article we are looking at the natural “learning process” of neuroplasticity which is the source of much hope and effort in rehabilitation.
The exciting discovery, revealed in glimpses over the last century, that the nervous system is plastic and adaptable even in adulthood, is a source of great hope to people with a spinal cord injury and other disorders such as stroke. We now call this inherent ability of the body to adapt, neuroplasticity, and recognise that the central nervous system (CNS) can undergo structural and functional change in response to new experiences.
What we don't know yet, is how to best take full advantage of this ability. Neuroplasticity represents the “potential” for some functional recovery but certainly does not guarantee it.
There are now plentiful books that “hype” the possibilities of plasticity and this is not particularly helpful when thinking about practical applications or goal setting for rehabilitation.
This discovery has led to promising new treatments and technologies for a range of conditions and, as we learn more about exploiting neuroplasticity, this should continue to lead to progress in rehabilitation. We could think of neuroplasticity as skill learning dependent – a process of applying a controlled “stimulus” of some sort and getting a beneficial outcome as a result.
In popular brain science literature, neuroplasticity is generally looked upon as a positive thing, but this is not always the case; without a training intervention, the body naturally adapts in response to injury and we might not like the result. (Kandel et al, 2013).
Currently, repeated practice and specific motor training are thought to provide the best opportunities to reverse the maladaptive plasticity associated with neuropathology. These should promote instead, the adaptive plasticity supportive of improved function. Basically - “we use it or lose it”. We can become a victim of the nervous system’s plasticity if we don’t act to take advantage of it.
How best to intervene?
There is a general consensus in the literature that it is best to intervene early in the recovery stages from a neurological condition and that there are several factors,commonly considered to be involved in motor learning and hence neuroplasticity. To some extent, they overlap:
Carrying out a motor skill practice - a physical activity, that is challenging, but not too difficult.
Practice should be specific.
Skill learning practice must be intense.
Technology can augment motor training.
Practice should be progressive.
Timing matters. Start early
Continuation of motor training for the long term
Engage intrinsic motivation to enhance the learning.
Availability of feedback to support learning
Let’s describe these in a bit more detail.
Research evidence shows that the difficulty of the task matters to the process of learning (Magness, 2022). The challenge is how to create a situation where practice is difficult and cognitively engaging, but not impossible. If the effort is perceived to be too much then frustration can be the result which is counterproductive. This is where technology can be very helpful and a skilled therapist who understands how to coach the patient.
Specificity effects have been recognised in learning research for more than 100 years, the general finding being that transfer of skills from practice to real-world application will be small unless the skills required are nearly identical. What this means is that general exercise and activities like strength training are most effective when combined with task-specific training programmes. Research is now looking at how easily practice in one task can transfer to another task in a meaningful way.
What do we mean by ‘intense’? Intensity implies that some combination of the training dose - overall volume, frequency and duration of training practice - is important to getting results. Although this suggestion is supported by research results, there is a lack of detail available when we try to pin down what exactly is a necessary and sufficient level of intensity for an individual case.
Technology can (indeed should) be a useful tool in motor training, as it can provide feedback, monitor progress, and enhance motivation. Examples of technology that can be used in motor training include virtual reality, robotics, and exergaming systems.
Some researchers point out that being able to tap into someone’s motivation to practise may be more effective in learning the skills for recovery than simply cranking up the intensity of the practice. The idea here is that focusing on practice simply to reduce impairment, is less motivating than looking at seeking benefits that might directly impact on the person’s quality of life.
There is no doubt that repeated attempts to solve a motor-control task benefit neuroplasticity and motor learning, but tasks must not be too simple or repetitive.
Simple tasks well within the capability of the performer will not induce neural plasticity but will produce boredom and lack of progress. Feedback is important in motor training too, as it helps the person to adjust their movements and improve their performance. Feedback that motivates can be provided by a therapist or through the use of technology such as sensors.
What’s really needed could be described as ‘repetition without repetition’.
Imagine learning a golf swing. This is an activity that involves lots of repetition. Let’s say you have been coached well, and you understand that learning the golf swing takes more than just rapidly hitting 1,000 golf balls down the driving range.
For each golf club swing, you learn to follow the same thoughtful process with careful setup and close attention to detail. However carefully you try to replicate each golf swing, there are going to be lots of small deviations in muscle and limb joint activity, and so on. What seems like exact repetition is not exactly so, but over time, you may consciously learn from your results and refine your swing. Sports people might refer to this as “greasing the groove”. It’s about paying careful attention to the detail of the movement and then carrying out many repetitions.
When I took up karate years ago I was told it would take a year to learn how to punch properly. On the face of it, this seems ridiculous - how hard can it be? Experienced practitioners of the art will understand that significant skill is involved in what seems like such a simple act.
When it comes to robotic systems that allow repetitive practice, (for example, the Indego Exoskeleton) perhaps the same observations hold. For example, the Icone robot for upper-limb rehabilitation allows the user to practise arm movement guided within an adjustable ‘haptic tunnel’. This allows the task to take place repetitively without constraining the movement to be the same with each repetition. Over time, the haptic tunnel’s size can be adjusted as the user’s performance improves.
Different forms of plasticity occur at different times during training. This implies that the timing of an intense therapy programme is important. Some researchers are advocating early interventions, for example, in the first month after a stroke. This seems to make sense, but a lot of stroke research has actually only been carried out in the chronic phase of recovery.
Many therapeutic interventions rely on extrinsic motivation to be effective. It seems to me that the best results come when motivation is intrinsic and the person’s mindset is adjusted to provide a consistent drive to work at improvement.
A final point should be an obvious one. Continuation of training is important: Motor training should be continued over a long period of time, even after the person has made significant progress. This helps to maintain gains and prevent regression. When you think about it, you and I do not go to the gym for a few weeks and expect to be fit for the rest of our lives.
Reading
Kandel, E.; Koster, J.; Mack, S.; Siegelbaum, S. (2013) Principles of Neural Science, 5th ed.; McGraw-Hill: New York, NY, USA, 2013.