Professor Stephan Swinnen of KU Leuven, Belgium, links behavioural sciences and neurosciences to study movement and neuroplasticity
Professor Stephan Swinnen’s movement control and neuroplasticity research group at KU Leuven has built a bridge between the behavioural sciences and the neurosciences in order to provide a multi-disciplinary study of movement control and neuroplasticity in normal and pathological conditions. As the cross-sectoral nature of this work suggests, various scientific disciplines are involved in this endeavour in order “to better understand normal ageing”, Swinnen said, adding:
“We study age-related changes in motor behaviour and learning/neuroplasticity and how these interact with alterations in brain function, brain structure (grey and white matter structure), brain connectivity and brain neurochemicals.”
Generating actions requires a good balance between the excitation and inhibition of neural networks. Swinnen said: “This balance can be affected as a result of ageing. We therefore want to better understand how brain activation patterns change as a function of ageing in terms of increased (or reduced) brain activity as compared to younger adults during the performance of simple and complex motor tasks.
Speaking to PEN, he said: “We have discovered that the integrity of brain structure is deterministic for motor performance quality. For example, the structure of the corpus callosum (white matter bundles connecting both hemispheres) determines the quality of the interactions between both hands.”
Swinnen’s team has also discovered that older adults often recruit a more extensive cortical territory (including prefrontal areas) than young adults to perform the same task, exemplifying how cognition penetrates into action as one ages.
Having established or described what these age-related changes in brain and motor behaviour are, the next question is how to improve or optimise this interplay via intervention. In other words, how plastic is the older brain?
“Traditionally, mainstream thinking was that the central nervous system is very plastic at a young age and becomes rigid … We often read about ageing as a biological mechanism that is both irreversible and inevitable, but we think this vastly underestimates the potential of the ageing brain.
“What the recent explosion of medical imaging research in neuroscience has revealed is a continuing or enduring plasticity of the brain into old age, not only functional but also structural, including brain re-organisation and rewiring that can be induced by task practice. As such, there is compensation, brain re-organisation and plasticity to preserve function against the backdrop of the degeneration that ultimately takes place.
“Our own medical imaging work demonstrates training-induced plastic changes in brain activation that are quite similar between young and old adults,” Swinnen explained.
This then begs the question about how neuroplasticity can be maximised in the ageing brain. The professor continued: “Optimising training protocols and providing the right task practice conditions is one approach. Physical activity/exercise is also critical for brain health.
“Additionally, non-invasive brain stimulation techniques (NIBS) can be used to enhance neuroplasticity. This can be done with various techniques that alter excitability in brain areas such as Transcranial Magnetic Stimulation (TMS), or the provision of direct or alternating currents to brain areas of interest. These may not only induce local effects at the targeted brain region but also global effects on the brain networks that orchestrate motor functions, perception, attention, etc. There is still quite some controversy surrounding the efficacy of these brain stimulation techniques, but massive scientific efforts will lead to improvements in the future.
“Since no perfect medical cure or pharmacological intervention exists to treat the degeneration of the brain and behavioural function during normal ageing, we need to rely on the lifelong plasticity of the brain that can be supported by mental and physical activity.”
Multidisciplinary approach – techniques
Swinnen’s multimodal/multidisciplinary approach requires the application of an umbrella of techniques:
1) Behavioural measurements, kinematics analysis and muscle registration techniques to determine the underlying patterns of muscle activity;
2) Imaging techniques to study the brain, e.g. functional imaging with high spatial or temporal resolution to study brain activity, such as (functional) magnetic resonance imaging (fMRI) or
high-density electroencephalography (hdEEG), structural imaging to study age-related alterations in brain grey and white matter, magnetic resonance spectroscopy (MRS) to study the concentration of neurochemicals, and finally the study about the interactions between brain areas, better known as brain connectivity in the context of brain networks; and
3) NIBS techniques are used to study the status of brain excitability and the status of local interactions between brain areas, using transcranial magnetic stimulation (TMS) techniques, either single pulse or dual-pulse or dual-site techniques.
“This multimodal approach requires a multidisciplinary team composed of behavioural scientists, neuroscientists, engineers, biologists, movement scientists, physical therapists, and so on,” Swinnen said.
Barriers for funding
In order to meet the main challenge associated with the demographic evolution of society, basic scientific research is required to better describe and characterise the nature of the age-related changes in brain and motor behaviour. Discussing this, Swinnen said: “For optimising these functions, we need to better understand the underlying mechanisms of neuroplasticity. We cannot skip that phase of basic research and instead focus primarily on applied research without a deeper mechanistic understanding. Funding agencies should be aware of that.”
Swinnen’s laboratory studies motor function within the broader context of behavioural functions, he said: “Medical imaging research on brain ageing is very much dominated by the study of cognitive processes, such as memory, language, etc. This is difficult to justify because motor functions are part of our everyday activities and are affected by ageing, such as the ability to preserve balance, to perform fine precision unimanual and bimanual skills such as grasping and manipulating objects, eating, tying shoelaces, buttoning a shirt.
“For example, reduced balance control can result in falls and have a huge impact on the older adults’ quality of life. I often experience a clear division between cognition and action even though these functions are intrinsically connected. These processes often operate in strong interaction with each other and should be studied in parallel. In daily life, movements often need to be planned in advance, or planned movements need to be suddenly suppressed or stopped. This is contingent to a balance between facilitation and inhibition and requires a close interaction between motor and non-motor brain areas. Medical imaging of motor functions constitutes only a very small portion of ageing neuroscience that is highly dominated by the study of cognitive functions.”
Some doubt whether healthy ageing is worth studying and suggest that massive resources should be directed to the cure of pathologies such as Alzheimer’s, Parkinson’s, etc. Asked about this, Swinnen said: “There is no doubt that these pathological conditions deserve our utmost attention. However, what about a preventive approach to increase the perspective of a healthy and independent life and to delay the occurrence of these diseases by maximising brain and mental health in older adults? This is equally of high relevance for society.”
“Enhancing lifelong learning and plasticity will help us face the challenges of rapidly changing contexts in a highly dynamic and technical society,” Swinnen explained, highlighting the following areas:
- How brain function, structure, networking and motor behaviour interact and how to boost brain plasticity;
- Development of closed-loop techniques to register brain function that will direct targeted brain stimulation to entrain brain activity for optimising behaviour;
- Study of the role of sleep in motor function and brain health;
- Study of brain activity at different timescales, from milliseconds to seconds, combining complementary imaging technologies (fMRI, hd-EEG); and
- How can suboptimal brain networks be restored or reorganised to improve interactions between local and distant brain regions?
For Swinnen, it is necessary to force a change in mindset towards ageing and to recognise the potential of older adults and their role in society: “This requires a change in attitude by the healthcare providers, family, and society at large,” he said, adding that “exploiting the plastic potential of the older brain and boosting this potential via intervention (task training, physical activity/exercise, non-invasive brain stimulation) will enhance older people’s continued presence in the labour market; increasing quality of life and comfortable independent living; and delaying the occurrence of debilitating age-related diseases … Huge socioeconomic implications are at stake in view of the ageing workforce in Europe.”
He also underlined the need for the demographic evolution not to be viewed as a problem, but as an opportunity to improve the quality of life of older adults and their involvement in society.
“Ageing is not simply degeneration of the brain and body,” he concluded. “It is a much more complex phenomenon characterised by reorganisation, compensation and enduring functional plasticity that can enhance the perspective of increased quality of life, functional independence, and sustained participation in society.”
- Research Programme of the Research Foundation – Flanders;
- Excellence of Science grant (EOS, 30446199, MEMODYN), Research Program of the Research Foundation Flanders;
- Francqui Research Foundation;
- Special Research Fund KU Leuven; and
- European Union’s Horizon 2020 Research and Innovation Programme.