A synergy-based hand control is encoded in human motor cortical areas

How the human brain controls hand movements to carry out different tasks is still debated. The concept of synergy has been proposed to indicate functional modules that may simplify the control of hand postures by simultaneously recruiting sets of muscles and joints. However, whether and to what extent synergic hand postures are encoded as such at a cortical level remains unknown. Here, we combined kinematic, electromyography, and brain activity measures obtained by functional magnetic resonance imaging while subjects performed a variety of movements towards virtual objects. Hand postural information, encoded through kinematic synergies, were represented in cortical areas devoted to hand motor control and successfully discriminated individual grasping movements, significantly outperforming alternative somatotopic or muscle-based models. Importantly, hand postural synergies were predicted by neural activation patterns within primary motor cortex. These findings support a novel cortical organization for hand movement control and open potential applications for brain-computer interfaces and neuroprostheses

A synergy-based hand control is encoded in human motor cortical areas

abstract: How the human brain controls hand movements to carry out different tasks is still debated. The concept of synergy has been proposed to indicate functional modules that may simplify the control of hand postures by simultaneously recruiting sets of muscles and joints. However, whether and to what extent synergic hand postures are encoded as such at a cortical level remains unknown. Here, we combined kinematic, electromyography, and brain activity measures obtained by functional magnetic resonance imaging while subjects performed a variety of movements towards virtual objects. Hand postural information, encoded through kinematic synergies, were represented in cortical areas devoted to hand motor control and successfully discriminated individual grasping movements, significantly outperforming alternative somatotopic or muscle-based models. Importantly, hand postural synergies were predicted by neural activation patterns within primary motor cortex. These findings support a novel cortical organization for hand movement control and open potential applications for brain-computer interfaces and neuroprostheses

Robotic hand augmentation drives changes in neural body representation

Humans have long been fascinated by the opportunities afforded through augmentation. This vision not only depends on technological innovations but also critically relies on our brain's ability to learn, adapt, and interface with augmentation devices. Here, we investigated whether successful motor augmentation with an extra robotic thumb can be achieved and what its implications are on the neural representation and function of the biological hand. Able-bodied participants were trained to use an extra robotic thumb (called the Third Thumb) over 5 days, including both lab-based and unstructured daily use. We challenged participants to complete normally bimanual tasks using only the augmented hand and examined their ability to develop hand-robot interactions. Participants were tested on a variety of behavioral and brain imaging tests, designed to interrogate the augmented hand's representation before and after the training. Training improved Third Thumb motor control, dexterity, and hand-robot coordination, even when cognitive load was increased or when vision was occluded. It also resulted in increased sense of embodiment over the Third Thumb. Consequently, augmentation influenced key aspects of hand representation and motor control. Third Thumb usage weakened natural kinematic synergies of the biological hand. Furthermore, brain decoding revealed a mild collapse of the augmented hand's motor representation after training, even while the Third Thumb was not worn. Together, our findings demonstrate that motor augmentation can be readily achieved, with potential for flexible use, reduced cognitive reliance, and increased sense of embodiment. Yet, augmentation may incur changes to the biological hand representation. Such neurocognitive consequences are crucial for successful implementation of future augmentation technologies

Early Movement Matters: Examining the Influence of Early Postnatal Caregiving Experiences of Term Infants on Motor and Head Shape Outcomes Across Infancy

The nurturing, handling and positioning exposures infants experience during daily caregiving contribute to their physical, motor, cognitive and social–emotional development. A relationship exists between infant sleep and wake-time positioning, the emergence of motor skills and the development of head shape deformities diagnosed as non-synostotic plagiocephaly (NSP). However, the underlying causal mechanism of the specific caregiving behaviours that may play a role remains unclear. The purpose of the study was to investigate the association between maternal caregiving behaviours and the developmental outcomes of ‘low-risk’ term infants in the first 10 months of life. The first phase of the research involved the establishment of an expert panel of experienced clinical practitioners and researchers to design, construct and validate an observational scale—the Infant Handling Measure—to measure the physical capabilities of an adult to move, lift, hold, position and play with a young infant (neonate to four months) during regular infant caregiving activities. The second phase was an exploratory prospective longitudinal birth cohort study. Data were collected over eight collection points (three home-based and five online telephone sessions) to explore the patterns and possible mechanisms by which early infant caregiving exposures may influence the developmental outcomes of healthy ‘low-risk’ term infants. Observations of infant motor and head shape outcomes were obtained at one, three and 10 months, and observations of maternal–infant handling were obtained at one and three months. Self-reported parenting measures were collected at the eight time points, and infant caregiving measures were collected at the seven postnatal time points. A final sample of 48 ‘low-risk’ term singleton infant (24 male; 27 firstborn)–mother dyads completed all observational measures. Mothers had the strongest influence on infant motor and head shape outcomes. Maternal knowledge about infant development and insufficient parenting instruction on infant handling, positioning and care practices were found to be important factors influencing caregiving abilities. The number of adverse perinatal health events, knowledge of infant development and mothers’ early infant handling skills contributed to infant motor development. Risk analysis confirmed maternal knowledge of infant development, the consistent provision of centred head and body positions and the vi adoption of rotational movements in infant care activities were protective and reduced the risk of delayed motor development. Three factors contributed to adverse infant head shape outcomes: insufficient parenting instruction on infant care practices, infants spending more than 17 hours per day in supine position during the first six months of life and the late adoption of rotational movements in daily infant care routines. Risk analysis confirmed that prior learning of handling techniques and adopting rotational movements in infant care activities were protective and reduced the risk of NSP. Early mastery of infant handling by mothers in the first months of life may be a salient mechanism of protection for infant motor and head shape development. Low maternal knowledge about infant development and insufficient parenting instruction on infant care practices highlight the gaps in current parenting strategies. A collaborative revision of early infant handling education, including consumers and stakeholders, is recommended

Sensory Processing and Movement Control in Children

Movement control and motor learning depend largely on sensory processing (SP) of different sensory inputs in order to make a relevant perceptual decision that can be expressed as a coordinated and goal-directed movement. The aim of this thesis is to explore the role of SP on perceptual decision-making, movement control and participation among children. The first study aimed to identify and summarise the role of SP on movement abilities among children with movement difficulties, particularly developmental coordination disorder (DCD), through a systematic review. This is due to the literature being replete with studies investigating the role of SP on movement among children with DCD, however, no updated systematic review to synthesise the findings has been published. Furthermore, because there is a paucity of empirical studies considering SP abilities in the context of the relationship between movement control, levels of and preferences for physical activity (PA) among children, the second study aimed to explore the relationship between them using four valid questionnaires. Finally, as limited research was found in the empirical literature that had investigated the effect of multisensory inputs on perceptual decision-making among children, the third study aimed to investigate the effect of multisensory versus unisensory stimuli on two elements contributing to perceptual decision-making (reaction time (RT) and accuracy). The first study showed that the various dimensions of SP significantly contribute to movement abilities in DCD. Moreover, the second study showed that movement abilities, levels of and preferences for PA may be influenced by SP abilities among children. Lastly, the third study showed that multisensory stimuli may enhance the process of decision-making, however, this was found to be more pronounced in older children. These results show clear evidence of the role of SP on movement and emphasise the importance of addressing SP abilities in assessments and intervention programmes

THE POTENTIATION OF ACTIONS BY VISUAL OBJECTS

This thesis examines the relation between visual objects and the actions they afford. It is proposed that viewing an object results in the potentiation of the actions that can be made towards it. The proposal is consistent with neurophysiological evidence that suggests that no clear divide exists between visual and motor representation in the dorsal visual pathway, a processing stream that neuropsychological evidence strongly implicates in the visual control of actions. The experimental work presented examines motor system involvement in visual representation when no intention to perform a particular action is present. It is argued that the representation of action-relevant visual object properties, such as size and orientation, has a motor component. Thus representing the location of a graspable object involves representations of the motor commands necessary to bring the hand to the object. The proposal was examined in a series of eight experiments that employed a Stimulus- Response Compatibility paradigm in which the relation between responses and stimulus properties was never made explicit. Subjects had to make choice reaction time responses that mimicked a component of an action that a viewed object afforded. The action-relevant stimulus property was always irrelevant to response determination and consisted of components of the reach and grasp movement. The results found are not consistent with explanations based on the abstract coding of stimulus-response properties and strongly implicate the involvement of the action system. They provide evidence that merely viewing an object results in the activation of the motor patterns necessary to interact with them. The actions an object affords are an intrinsic part of its visual representation, not merely on account of the association between objects and familiar actions but because the motor system is directly involved in the representation of visuo-spatial object properties