This Special Issue is to commemorate the scientific contributions of Stephan Swinnen as he retires from his position at KU Leuven. As the Director of Movement Control and Neuroplasticity Research Group, he has led a multidisciplinary, international team of scientists in cognitive and motor neuroscience. From the start of his training at the University of California at Los Angeles, under the direction of Richard Schmidt, he has investigated the cognitive control of action. Throughout his career, he continually adopted a diverse range of biomedical imaging techniques that has led to a greater understanding of how the brain coordinates complex movement. His research on interlimb coordination in healthy and pathological states across the lifespan has made him a leader in the field. This festschrift is a testament to that and represents only a sample of his contributions.
The role of feedback in skilled motor performance has a rich history in theories and applications of motor control. In this festschrift, Herbaut and colleagues examine how strategic use of visual and haptic cues influence acquisition of fundamental skills in tennis, specifically in youth. Their findings convincingly demonstrate that thoughtful, informed use of feedback significantly enhances acquisition of complex motor skills, even at an early age. In a literature review article, Fling and colleagues emphasize the critical role that somatosensory systems play in motor control. The augmentation of feedback through the combined use of electrical stimulation, such as tDCS and virtual reality, represents exciting emerging technologies to accelerate skilled motor learning in diverse populations.
Three research articles focus on neurorehabilitation in clinical settings. Goble and colleagues present exciting data on lower limb asymmetry. They implement the widely used Single Leg Stance protocol in a novel way using a portable, force-plate technology, the Balance Tracking System (BTrackS). This study reveals a new benchmark in the asymmetry index of young healthy adults. Meulenbroek and colleagues report a unique approach to clinical interventions of knee osteoarthritis, a disease affecting nearly one million people in The Netherlands alone. Their method uses non-linear tools and considers both upper and lower extremities in order to improve clinical assessment of this widespread pathological condition. By considering interlimb coordination of both the upper and lower extremities, they identify a more stable frame of reference to assist clinicians in patient recovery. Dounskaia and colleagues examine the dynamic forces that drive bimanual reaching by considering the interaction of forces at multiple joints, i.e. shoulder, elbow, and wrists, in stroke patients. Their study sheds new light on best practices for clinical interventions.
Finally, to understand the structural-functional interactions of the brain, it is necessary to develop robust models of neuroimaging data. In their review article, Pauwels and Gooijers update the literature in this rapidly advancing area with a focus on new corpus callosum parcellation techniques, including functional MRI- and atlas-informed tractography. The largest white matter tract of the brain is clearly not a uniform bundle of fibers, nor can it simply be geometrically divided into genu, rostrum, and splenium, as has been classically done. The diameter, density, and direction of axons as well as degree of myelination all contribute to the dependent measures that are extracted from modeling techniques, such as fractional anisotropy. Their review article highlights in vivo histological approaches that are instrumental in revealing the role that the corpus callosum plays in bimanual coordination of young, aged, and pathological conditions.
On a personal note, Stephan Swinnen was my postdoctoral mentor for two short, but impactful, years (2009-2011) at KU Leuven. Upon news of his retirement, I was compelled to mark the occasion with a festschrift. There were many students and collaborators who only learned of this tribute after the brief announcement period had already closed. By recent estimates, he has over 500 publications, 25,000 citations, and is currently overseeing more than 35 scientists at various stages. When a career spans so many decades and touches so many lives, to try to capture its entire breadth is to attempt the impossible. Thank you to the many authors and reviewers who contributed their time to the production of this Special Issue.
Disclosure statement
No potential conflict of interest was reported by the author(s).