Somatosensory-Evoked Potentials as a Marker of Functional Neuroplasticity in Athletes: A Systematic Review

BackgroundSomatosensory-evoked potentials (SEP) represent a non-invasive tool to assess neural responses elicited by somatosensory stimuli acquired via electrophysiological recordings. To date, there is no comprehensive evaluation of SEPs for the diagnostic investigation of exercise-induced functional neuroplasticity. This systematic review aims at highlighting the potential of SEP measurements as a diagnostic tool to investigate exercise-induced functional neuroplasticity of the sensorimotor system by reviewing studies comparing SEP parameters between athletes and healthy controls who are not involved in organized sports as well as between athlete cohorts of different sport disciplines.MethodsA systematic literature search was conducted across three electronic databases (PubMed, Web of Science, and SPORTDiscus) by two independent researchers. Three hundred and ninety-seven records were identified, of which 10 cross-sectional studies were considered eligible.ResultsDifferences in SEP amplitudes and latencies between athletes and healthy controls or between athletes of different cohorts as well as associations between SEP parameters and demographic/behavioral variables (years of training, hours of training per week & reaction time) were observed in seven out of 10 included studies. In particular, several studies highlight differences in short- and long-latency SEP parameters, as well as high-frequency oscillations (HFO) when comparing athletes and healthy controls. Neuroplastic differences in athletes appear to be modality-specific as well as dependent on training regimens and sport-specific requirements. This is exemplified by differences in SEP parameters of various athlete populations after stimulation of their primarily trained limb.ConclusionTaken together, the existing literature suggests that athletes show specific functional neuroplasticity in the somatosensory system. Therefore, this systematic review highlights the potential of SEP measurements as an easy-to-use and inexpensive diagnostic tool to investigate functional neuroplasticity in the sensorimotor system of athletes. However, there are limitations regarding the small sample sizes and inconsistent methodology of SEP measurements in the studies reviewed. Therefore, future intervention studies are needed to verify and extend the conclusions drawn here.

Prehension kinematics in humans and macaques

Non-human primates, especially rhesus macaques, have been a dominant model to study sensorimotor control of the upper limbs. Indeed, human and macaques have similar hands and homologous neural circuits to mediate manual behavior. However, few studies have systematically and quantitatively compared the manual behaviors of the two species. Such comparison is critical for assessing the validity of using the macaque sensorimotor system as a model of its human counterpart. In this study, we systematically compared the prehensile behaviors of humans and rhesus macaques using an identical experimental setup. We found human and macaque prehension kinematics to be generally similar but with a few subtle differences. Humans and macaques have similar major axes of movements and similar kinematics subspaces. Human grasps are more object-specific and the movement of human digits are less correlated with each other. Monkeys demonstrate more stereotypical grasping behaviors that are common across all grasp conditions. Our results bolster the use of the macaque model to understand the neural mechanisms of manual dexterity.

From Affordances to Abstract Words: The Flexibility of Sensorimotor Grounding

The sensorimotor system plays a critical role in several cognitive processes. Here, we review recent studies documenting this interplay at different levels. First, we concentrate on studies that have shown how the sensorimotor system is flexibly involved in interactions with objects. We report evidence demonstrating how social context and situations influence affordance activation, and then focus on tactile and kinesthetic components in body–object interactions. Then, we turn to word use, and review studies that have shown that not only concrete words, but also abstract words are grounded in the sensorimotor system. We report evidence that abstract concepts activate the mouth effector more than concrete concepts, and discuss this effect in light of studies on adults, children, and infants. Finally, we pinpoint possible sensorimotor mechanisms at play in the acquisition and use of abstract concepts. Overall, we show that the involvement of the sensorimotor system is flexibly modulated by context, and that its role can be integrated and flanked by that of other systems such as the linguistic system. We suggest that to unravel the role of the sensorimotor system in cognition, future research should fully explore the complexity of this intricate, and sometimes slippery, relation.

From Affordances to Abstract Words: The Flexibility of the Sensorimotor Grounding

Recent research has shown that the sensorimotor system plays a significant role in a variety of cognitive processes. In this paper, we will review recent studies performed in our lab (Body Action Language Lab, BALLAB) or in labs with which we collaborate, showing the involvement of the sensorimotor system at different levels. With the purpose of expounding on this aspect, we focus on studies that highlight two main characteristics of the involvement of the sensorimotor systems. First, we concentrate on the flexibility of sensorimotor grounding during interaction with objects. We report evidence showing how social context and current situations influence affordance activation. We then focus on the tactile and kinesthetic involvement in body-object interaction. Second, we illustrate flexible sensorimotor grounding in word use. We review studies showing that not only concrete words, like “bottle,” but also abstract words, like “freedom,” “thinking,” and “perhaps,” are grounded in the sensorimotor system. We report evidence showing that abstract words activate sensory modalities and involve the mouth effector more than concrete words due to their privileged relationship with language, both outer and inner speech. We discuss the activation of the mouth sensorimotor system in light of studies on adults (e.g., studies employing articulatory suppression), children (e.g., studies on the effects of pacifier use on word acquisition and processing), and infants (e.g. studies on emergence of new words). Finally, we pinpoint possible mechanisms at play in the acquisition and use of abstract concepts. We argue that with abstract concepts, we rely more on other people to learn or negotiate the meaning of words; we have called this mechanism social metacognition.Social metacognition is bidirectionally linked to our sensorimotor system. On the one hand, linguistic explanations constitute a primary source of grounding that may be re-enacted when retrieving a concept, for example through inner speech. On the other hand, it leads us to feel closer and be more synchronous in movement with others, who can help us understand the meaning of very complex words. Overall, we show that the sensorimotor system provides a grounding basis not only for objects and concrete words but also for more abstract and concrete ones. We conclude by arguing that future research should address and deepen two different and interrelated aspects concerning the involvement of the sensorimotor system during object and word processing. First, the sensorimotor system is flexibly modulated by the context, as studies on affordances reveal. Second, the sensorimotor system can be involved at different levels, and its role can be integrated and flanked by that of other systems, like the linguistic one, as studies on abstract concepts clearly show. We urge future research aimed at unravelling the role of the sensorimotor system in cognition to fully explore the complexity of this intricate-and sometimes slippery-relation.

Sensorimotor and body perception assessments of nonspecific chronic low back pain: a cross-sectional study

Background Low back pain (LBP) is one of the most common musculoskeletal disorders, causing significant personal and social burden. Current research is focused on the processes of the central nervous system (particularly the sensorimotor system) and body perception, with a view to developing new and more efficient ways to treat chronic low back pain (CLBP). Several clinical tests have been suggested that might have the ability to detect alterations in the sensorimotor system. These include back-photo assessment (BPA), two-point discrimination (TPD), and the movement control tests (MCT). The aim of this study was to determine whether the simple clinical tests of BPA, TPD or MCT are able to discriminate between nonspecific CLBP subjects with altered body perception and healthy controls. Methods A cross-sectional study was conducted. At one point in time, 30 subjects with CLBP and 30 healthy controls were investigated through using BPA, TPD and MCT on the lower back. Correlations among the main covariates and odds ratios for group differences were calculated. Results MCT showed an odds ratio for the presence of CLBP of 1.92, with a statistically significant p-value (0.049) and 95%CI. The TPD and BPA tests were unable to determine significant differences between the groups. Conclusions Of the three tests investigated, MCT was found to be the only suitable assessment to discriminate between nonspecific CLBP subjects and healthy controls. The MCT can be recommended as a simple clinical tool to detect alterations in the sensorimotor system of nonspecific CLBP subjects. This could facilitate the development of tailored management strategies for this challenging LBP subgroup. However, further research is necessary to elucidate the potential of all the tests to detect alterations in the sensorimotor system of CLBP subjects. Trial registration No trial registration was needed as the study contains no intervention. The study was approved by the Swiss Ethics Commission of Northwest and Central Switzerland (EKNZ) reference number 2015–243.

Next-Generation Prosthetic Hand: from Biomimetic to Biorealistic

Integrating a prosthetic hand to amputees with seamless neural compatibility presents a grand challenge to neuroscientists and neural engineers for more than half century. Mimicking anatomical structure or appearance of human hand does not lead to improved neural connectivity to the sensorimotor system of amputees. The functions of modern prosthetic hands do not match the dexterity of human hand due primarily to lack of sensory awareness and compliant actuation. Lately, progress in restoring sensory feedback has marked a significant step forward in improving neural continuity of sensory information from prosthetic hands to amputees. However, little effort has been made to replicate the compliant property of biological muscle when actuating prosthetic hands. Furthermore, a full-fledged biorealistic approach to designing prosthetic hands has not been contemplated in neuroprosthetic research. In this perspective article, we advance a novel view that a prosthetic hand can be integrated harmoniously with amputees only if neural compatibility to the sensorimotor system is achieved. Our ongoing research supports that the next-generation prosthetic hand must incorporate biologically realistic actuation, sensing, and reflex functions in order to fully attain neural compatibility.

Space, time and number: common coding mechanisms and interactions between domains

Space, time and number are key dimensions that underlie how we perceive, identify and act within the environment. They are interconnected in our behaviour and brain. In this study, we examined interdependencies between these dimensions. To this end, left- and right-handed participants performed an object collision task that required space–time processing and arithmetic tests that involved number processing. Handedness of the participants influenced collision detection with left-handers being more accurate than right-handers, which is in line with the premise that hand preference guides individual differences as a result of sensorimotor experiences and distinct interhemispheric integration patterns. The data further showed that successful collision detection was a predictor for arithmetic achievement, at least in right-handers. These findings suggest that handedness plays a mediating role in binding information processing across domains, likely due to selective connectivity properties within the sensorimotor system that is guided by hemispheric lateralisation patterns.