Assessing Performance, Role Sharing, and Control Mechanisms in Human-Human Physical Interaction for Object Manipulation

abstract: Object manipulation is a common sensorimotor task that humans perform to interact with the physical world. The first aim of this dissertation was to characterize and identify the role of feedback and feedforward mechanisms for force control in object manipulation by introducing a new feature based on force trajectories to quantify the interaction between feedback- and feedforward control. This feature was applied on two grasp contexts: grasping the object at either (1) predetermined or (2) self-selected grasp locations (“constrained” and “unconstrained”, respectively), where unconstrained grasping is thought to involve feedback-driven force corrections to a greater extent than constrained grasping. This proposition was confirmed by force feature analysis. The second aim of this dissertation was to quantify whether force control mechanisms differ between dominant and non-dominant hands. The force feature analysis demonstrated that manipulation by the dominant hand relies on feedforward control more than the non-dominant hand. The third aim was to quantify coordination mechanisms underlying physical interaction by dyads in object manipulation. The results revealed that only individuals with worse solo performance benefit from interpersonal coordination through physical couplings, whereas the better individuals do not. This work showed that naturally emerging leader-follower roles, whereby the leader in dyadic manipulation exhibits significant greater force changes than the follower. Furthermore, brain activity measured through electroencephalography (EEG) could discriminate leader and follower roles as indicated power modulation in the alpha frequency band over centro-parietal areas. Lastly, this dissertation suggested that the relation between force and motion (arm impedance) could be an important means for communicating intended movement direction between biological agents.Dissertation/ThesisDoctoral Dissertation Biomedical Engineering 201

EEG-based Signatures of Isometric Arm Forces by Females at Different Levels of Physical Exertion and Comfort

In recent years, electroencephalography (EEG) has become a valuable technique for ergonomics studies of physical activities and other real-life tasks. Since the perception of force exertion is influenced by various psychophysical, cognitive, and social factors, different subjective measures have been traditionally used to measure the perception of physical exertion and related body discomfort. Along with the subjective measures, research showed that neural signals are also necessary objective measures to understanding human perception of physical tasks. However, EEG signatures of different physical exertion levels and perceived physical comfort have not been explored. The main objective of this study was to investigate EEG activity measured by power spectral density (PSD) for isometric arm forces at different levels of physical exertion and physical comfort. The first part of the study investigated PSD changes at five predefined force exertion levels, i.e., extremely light, light, somewhat hard, hard, and extremely hard. The healthy female participants performed physical exertions and rated their level of experienced physical comfort. Significant differences in force exertion and PSD for theta, beta, and gamma waves were observed. Significant correlations were also found between PSD, force, and rating of physical comfort (RPPC). In the second part of the study, PSD changes at predefined physical comfort levels were investigated, namely at very low, moderate, fair, high, and very high comfort levels. The participants also rated the level of perceived physical exertion. Significant differences in force exertion and comfort levels for theta, beta, and gamma power were found. In addition, significant correlations were found between PSD, force, and rate of physical exertion (RPE). Overall, this is a novel study where EEG signatures of isometric efforts by females have been investigated at different force and physical comfort levels. The reported results should improve our understanding of the neural correlates of physical tasks performed by females

Drawing, Handwriting Processing Analysis: New Advances and Challenges

International audienceDrawing and handwriting are communicational skills that are fundamental in geopolitical, ideological and technological evolutions of all time. drawingand handwriting are still useful in defining innovative applications in numerous fields. In this regard, researchers have to solve new problems like those related to the manner in which drawing and handwriting become an efficient way to command various connected objects; or to validate graphomotor skills as evident and objective sources of data useful in the study of human beings, their capabilities and their limits from birth to decline

Reach to grasp movement: a simultaneous recording approach

In our everyday life, we interact continually with objects. We reach for them, we grasp them, we manipulate them. All these actions are apparently very simple. Yet, this is not so. The mechanisms that underlie them are complex, and require multiple visuomotor transformations entailing the capacity to transform the visual features of the object in the appropriate hand configuration, and the capacity to execute and control hand and finger movements. In neural terms, grasping behavior can be dissociated into separate reach and grip components. According to this view, computations regarding the grasp component occurs within a lateral parietofrontal circuit involving the anterior intraparietal area (AIP) and both the dorsal (PMd) and the ventral (PMv) premotor areas. The general agreement is that the processes occurring in AIP constitute the initial step of the transformation leading from representation of objects to movement aimed at interacting with such objects. Evidence supporting this view comes from neurophysiological studies showing that the representation of three-dimensional object features influences both the rostral sector of the ventral premotor cortex (area F5) and the ventro-rostral sector of the dorsal premotor area (area F2vr; for review see Filimon, 2010). With respect to the reach component, there is agreement that it is subserved by a more medial parieto-frontal circuit including the medial intraparietal area (mIP) termed as the parietal reach region (PRR), area V6A, and the dorsal premotor area F2. Human neuroimaging studies go in the same direction. They showed the involvement of the anterior portion of the human AIP in grasping behavior and they proposed human homologues of both the ventral and dorsal premotor cortices during grasping. Whereas, reaching activates the medial intraparietal and the superior parieto-occipital cortex (for review see Castiello & Begliomini, 2008). Altogether these studies suggest that in humans, like in monkeys, reach to grasp movements involve a large network of interconnected structures in the parietal and frontal lobes. And, that this cortical network is differentially involved for the control of distinct aspects characterizing the planning and the control of reach to grasp movement. Nevertheless, how the neural control systems interact with the complex biomechanics of moving limbs - as to help us to identify the operational principles to look for in reach to grasp studies and, more in general, in motor control - remains an open question. In this respect, it is only through the use of converging techniques with different characteristics that we might fully understand how the human brain controls the grasping function. What is so far lacking in the literature on cortical control of grasp in humans is a systematic documentation of the time course of neural activity during performance of reach to grasp movement. To fill this gap the present thesis will consider the co-registration of behavioural and neural events in order to provide deeper insights into the neuro-functional basis of reach to grasp movements in humans. In Chapter 1 an overview on the state of the art in many disciplines investigating reach to grasp processes will be provided, with particular attention to neurophysiology, from which most of the knowledge regarding the neural underpinnings of reach to grasp movements comes from. Furthermore, kinematical as well as neuroimaging, and evoked related potentials (ERP) investigations will be reviewed. Particular emphasis will be given to neuroimaging studies, especially those exploring grasping movements by functional magnetic resonance imaging (fMRI), as the technique adopted to conduct the studies presented in this thesis (Chapter 1). Basic principles of co-registration techniques, which are at the core of the methodological aspect of the present thesis, will be reviewed (Chapter 2). In this respect, a description of the methodologies adopted in the present thesis together with general information regarding signal processing and data analysis for these different techniques will be provided in specific appendices (III, IV). Then, three studies focusing on the co-registration of kinematical with ERP (Chapters 3 and 4) and FMRI with ERP (Chapter 5) will be presented and discussed. In Chapter 3 the co-registration of ERP and kinematical signals will be considered with specific reference to hand shaping, that is the grasp component of the targeted movement. A similar co-registration approach will be adopted in Chapter 4 for investigating the underlying circuits of reaching. The focus for Chapter 5 will be the co-registration of ERPs and fMRI signals as to reveal the time course of activation of the differential cortical areas related to the planning, initiation and on-line control of reaching and grasping movements and how such activity varies depending on object size. A general discussion (Chapter 6), contextualizing the results obtained by the studies presented in this thesis will follow

Neuromechanical Tuning for Arm Motor Control

Movement is a fundamental behavior that allows us to interact with the external world. Its importance to human health is most evident when it becomes impaired due to disease or injury. Physical and occupational rehabilitation remains the most common treatment for these types of disorders. Although therapeutic interventions may improve motor function, residual deficits are common for many pathologies, such as stroke. The development of novel therapeutics is dependent upon a better understanding of the underlying mechanisms that govern movement. Movement of the human body adheres to the principles of classic Newtonian mechanics. However, due to the inherent complexity of the body and the highly variable repertoire of environmental contexts in which it operates, the musculoskeletal system presents a challenging control problem and the onus is on the central nervous system to reliably solve this problem. The neural motor system is comprised of numerous efferent and afferent pathways with a hierarchical organization which create a complex arrangement of feedforward and feedback circuits. However, the strategy that the neural motor system employs to reliably control these complex mechanics is still unknown. This dissertation will investigate the neural control of mechanics employing a “bottom-up” approach. It is organized into three research chapters with an additional introductory chapter and a chapter addressing final conclusions. Chapter 1 provides a brief description of the anatomical and physiological principles of the human motor system and the challenges and strategies that may be employed to control it. Chapter 2 describes a computational study where we developed a musculoskeletal model of the upper limb to investigate the complex mechanical interactions due to muscle geometry. Muscle lengths and moment arms contribute to force and torque generation, but the inherent redundancy of these actuators create a high-dimensional control problem. By characterizing these relationships, we found mechanical coupling of muscle lengths which the nervous system could exploit. Chapter 3 describes a study of muscle spindle contribution to muscle coactivation using a computational model of primary afferent activity. We investigated whether these afferents could contribute to motoneuron recruitment during voluntary reaching tasks in humans and found that afferent activity was orthogonal to that of muscle activity. Chapter 4 describes a study of the role of the descending corticospinal tract in the compensation of limb dynamics during arm reaching movements. We found evidence that corticospinal excitability is modulated in proportion to muscle activity and that the coefficients of proportionality vary in the course of these movements. Finally, further questions and future directions for this work are discussed in the Chapter 5

Electroencephalograph Recording with Ten-Twenty Electrode System Based on Arduino Mega 2560

Improved Technology until now started to help many aspects of human works, including medical facilities. One of them is Electroencephalography (EEG) which records electrical activities of the brain. This technology is used to diagnose any brain disease that makes an abnormality at EEG signal recording. EEG usually has non-invasive methods, where electrodes placed on the scalp that easy and reusable. This technology itself has been started in 1924 by Hans Berger. This paper discusses the basic construction of EEG, focused on simulation, device construction, and results from devices. It will further mention how Arduino Mega 2560 record analog signals, circuit diagrams that will be used, and final results that showed and processed on SCILAB application. The final result would use Ten-Twenty Electrode System which can be compared with any result from any different recording and be displayed in SCILAB with graph form that has been filtered with Fast Fourier Transform (FFT) results

Neurophysiological correlates of preparation for action measured by electroencephalography

The optimal performance of an action depends to a great extend on the ability of a person to prepare in advance the appropriate kinetic and kinematic parameters at a specific point in time in order to meet the demands of a given situation and to foresee its consequences to the surrounding environment. In the research presented in this thesis, I employed high-density electroencephalography in order to study the neural processes underlying preparation for action. A typical way for studying preparation for action in neuroscience is to divide it in temporal preparation (when to respond) and event preparation (what response to make). In Chapter 2, we identified electrophysiological signs of implicit temporal preparation in a task where such preparation was not essential for the performance of the task. Electrophysiological traces of implicit timing were found in lateral premotor, parietal as well as occipital cortices. In Chapter 3, explicit temporal preparation was assessed by comparing anticipatory and reactive responses to periodically or randomly applied external loads, respectively. Higher (pre)motor preparatory activity was recorded in the former case, which resulted in lower post-load motor cortex activation and consequently to lower long-latency reflex amplitude. Event preparation was the theme of Chapter 4, where we introduced a new method for studying (at the source level) the generator mechanisms of lateralized potentials related to response selection, through the interaction with steady-state somatosensory responses. Finally, in Chapter 5 we provided evidence for the existence of concurrent and mutually inhibiting representations of multiple movement options in premotor and primary motor areas.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Cortico-muscular coherence in sensorimotor synchronisation

This thesis sets out to investigate the neuro-muscular control mechanisms underlying the ubiquitous phenomenon of sensorimotor synchronisation (SMS). SMS is the coordination of movement to external rhythms, and is commonly observed in everyday life. A large body of research addresses the processes underlying SMS at the levels of behaviour and brain. Comparatively, little is known about the coupling between neural and behavioural processes, i.e. neuro-muscular processes. Here, the neuro-muscular processes underlying SMS were investigated in the form of cortico-muscular coherence measured based on Electroencephalography (EEG) and Electromyography (EMG) recorded in human healthy participants. These neuro-muscular processes were investigated at three levels of engagement: passive listening and observation of rhythms in the environment, imagined SMS, and executed SMS, which resulted in the testing of three hypotheses: (i) Rhythms in the environment, such as music, spontaneously modulate cortico-muscular coupling, (ii) Movement intention modulates cortico-muscular coupling, and (iii) Cortico-muscular coupling is dynamically modulated during SMS time-locked to the stimulus rhythm. These three hypotheses were tested through two studies that used Electroencephalography (EEG) and Electromyography (EMG) recordings to measure Cortico-muscular coherence (CMC). First, CMC was tested during passive music listening, to test whether temporal and spectral properties of music stimuli known to induce groove, i.e., the subjective experience of wanting to move, can spontaneously modulate the overall strength of the communication between the brain and the muscles. Second, imagined and executed movement synchronisation was used to investigate the role of movement intention and dynamics on CMC. The two studies indicate that both top-down, and somatosensory and/or proprioceptive processes modulate CMC during SMS tasks. Although CMC dynamics might be linked to movement dynamics, no direct correlation between movement performance and CMC was found. Furthermore, purely passive auditory or visual rhythmic stimulation did not affect CMC. Together, these findings thus indicate that movement intention and active engagement with rhythms in the environment might be critical in modulating CMC. Further investigations of the mechanisms and function of CMC are necessary, as they could have important implications for clinical and elderly populations, as well as athletes, where optimisation of motor control is necessary to compensate for impaired movement or to achieve elite performance