L'effet de la pratique de mouvements par imagerie motrice sur l'apprentissage d'habiletés et l'organisation cérébrale fonctionnelle

The main objective of this thesis was to examine the behavioural and functional cerebral reorganization produced by the mental practice of a motor skill in order to promote the use of this training method in neurologic rehabilitation. A first study was conducted to validate a new foot sequence task (FST) that allows precise measurement of the learning of sequential foot movements in normal subjects and patients with motor impairments. The results of a second study, which aimed at determining if motor imagery is essential to the learning of the FST through mental practice, showed that mental practice with motor imagery improved the learning of this task more than physical practice alone. Moreover, it was found that another type of mental practice, verbal rehearsal, can also improve the learning of the FST. However, only the subjects that had used motor imagery during practice remembered the sequence after several months without practice, which suggests that motor imagery contributes to learning but more importantly, that it is essential for the long term retention of motor skills learned with mental practice. A single-case study was then conducted to examine the effect of combined physical and mental practice on the learning of the FST in a patient who had had a stroke 4 months earlier. The results confirm that MP with motor imagery can improve the learning of this task when combined with physical practice and can contribute to the retention of the skill when used alone. Finally, a study using positron emission tomography showed that subjects who practiced the FST with motor imagery improved their performance, and displayed a functional reorganization similar to that observed after physical practice. However, practice with motor imagery seems to produce changes on the systems subserving motor preparation and anticipation rather than execution per se. Overall, the findings of this thesis confirm that MP with motor imagery is efficient at improving motor skill learning, and that this form of training changes the cerebral organization of subjects. The various results also provided new guidelines for future research and the use of mental practice in a neurologic rehabilitation

Neural circuits involved in imitation and perspective-taking

Is it important to adopt the perspective of the model when learning a new skill? Is the “mirror system” equally involved when the teacher is facing or side-by-side with students? In this functional MRI study, we measured the cerebral hemodynamic changes in participants who watched video-clips depicting simple hand or foot actions. The participants either watched passively or imitated these actions. Half the video-clips depicted actions filmed from the perspective of the participant (1st-person perspective) and half from a frontal view as if watching someone else (3rd-person perspective). Behavioral results showed that latency to imitate was significantly shorter for the 1st-person perspective than the 3rd-person perspective. Functional imaging results demonstrate that the observation of intransitive actions engaged primary visual and extrastriate visual areas, but not the premotor cortex. Imitation vs. observation of actions yielded enhanced signal in the contralateral somatosensory and motor cortices, cerebellum, left inferior parietal lobule and superior parietal cortex, and left ventral premotor cortex. Activity in the lateral occipital cortex around the extrastriate body area was significantly enhanced during imitation, as compared to observation of actions confirming that this region involvement reaches beyond the perception of body parts. Moreover, comparisons of the two visual perspectives showed more activity in the left sensory–motor cortex for 1st-person, even during observation alone, and in the lingual gyrus for 3rd-person perspective. These findings suggest that the 1st-person perspective is more tightly coupled to the sensory-motor system than the 3rd-person perspective, which requires additional visuospatial transformation

Mirroring Pain in the Brain: Emotional Expression versus Motor Imitation

Perception of pain in others via facial expressions has been shown to involve brain areas responsive to self-pain, biological motion, as well as both performed and observed motor actions. Here, we investigated the involvement of these different regions during emotional and motor mirroring of pain expressions using a two-task paradigm, and including both observation and execution of the expressions. BOLD responses were measured as subjects watched video clips showing different intensities of pain expression and, after a variable delay, either expressed the amount of pain they perceived in the clips (pain task), or imitated the facial movements (movement task). In the pain task condition, pain coding involved overlapping activation across observation and execution in the anterior cingulate cortex, supplementary motor area, inferior frontal gyrus/anterior insula, and the inferior parietal lobule, and a pain-related increase (pain vs. neutral) in the anterior cingulate cortex/supplementary motor area, the right inferior frontal gyrus, and the postcentral gyrus. The 'mirroring' response was stronger in the inferior frontal gyrus and middle temporal gyrus/superior temporal sulcus during the pain task, and stronger in the inferior parietal lobule in the movement task. These results strongly suggest that while motor mirroring may contribute to the perception of pain expressions in others, interpreting these expressions in terms of pain content draws more heavily on networks involved in the perception of affective meaning

Improving empathy in the care of pain patients

Empathy is associated with countless benefits in clinical interactions, yet it is not always optimal in health care providers. Social neuroscience offers a window onto the cerebral processes underlying the complex relationships between the multiple components of empathy, patient care, and the caregiver’s well-being. Neuroimaging studies have revealed patterns of empathyrelated neural responses that shed some light on the mechanisms that could partially explain the phenomena of empathy decline and pain underestimation in health care providers. Such information, complementary to behavioral research findings, may help develop new means of improving empathy in health care, as long as interpretation of neuroimaging data remains grounded. Additionally, research on empathy in this context has largely focused on how clinicians’ empathy may affect patient outcomes, but the relationship between empathy and well-being in health care providers is often neglected. The quest to optimize empathy in patient–clinician interactions must take into account the welfare of both members of this dyad

Toward dynamic pain expressions in avatars : perceived realism and pain level of diffrent action unit orders

The facial expression of pain can be decomposed in three sets of Action Units (AUs), the smallest discriminating facial movements: Brow lowering (B), Nose wrinkling + Upper lip raising (N), and Orbit tightening + Eyelid closure (O). This study compared the perception of realism and pain level from different onset orders of AUs in avatars. Seven videos of facial expressions of pain were created with four different avatars (2 women): six sequential onsets combining the three sets of AUs and one synchronized onset. 45 healthy adults (22 women; aged 23.6 ± 5.2 years) rated the realism of facial movements, and the level of intensity and unpleasantness of perceived pain. A more realistic expression was associated with the onset of O before or at the same time as N, a more intense expression was associated when B occurred last, and a higher level of unpleasantness was associated with the onset of N before B. Therefore, the sequence ONB yielded the highest ratings on both measures of realism and pain levels. These findings describe the perceived content of different orders of facial movements that could contribute to the creation of realistic pain-expressing virtual agents designed to study human-computer interactions

Editorial: Mental practice: Clinical and experimental research in imagery and action observation

First paragraph: This editorial accompanies 18 articles as part of aFrontiersresearch topic. The aim of this research topic was to clarify the underlying mechanisms involved in mental practice of action, bringing together evidence from a range of disciplines including cognitive neuroscience, experimental neuropsychology, sport and movement science, clinical neuropsychology and clinical neurology. The need to clarify the underlying mechanisms of mental practice is a pressing one. Mental practice of action has been explored in sport psychology for several decades, with the aim to use mental practice to improve sport performance. However, following the discovery of the mirror neuron system (see for example,Rizzolatti and Craighero, 2004), the perspective of mental practice has changed to a rationale based on neuroscience and to research focussed on understanding the neural processes of mental practice. Evidence that the brain simulates action has resulted in a common understanding of “functional equivalence” (Jeannerod, 1994): the idea that thementalrepresentation of an action or percept in the person's mind is the neural “equivalent” to thephysicalaction oractualpercept. This ability to mentally represent action using the motor system allows for action simulation, providing conscious mental rehearsal of movement (imagery), but also allows for a common percept when observing the movements of others. Finally, in recent years, the disciplines of clinical neuropsychology and neurology have begun to use mental rehearsal of action, ormental practice, to produce improvements normally attributed to practicing actual movements

EEVEE : the Empathy-Enhancing Virtual Evolving Environment

Empathy is a multifaceted emotional and mental faculty that is often found to be affected in a great number of psychopathologies, such as schizophrenia, yet it remains very difficult to measure in an ecological context. The challenge stems partly from the complexity and fluidity of this social process, but also from its covert nature. One powerful tool to enhance experimental control over such dynamic social interactions has been the use of avatars in virtual reality (VR); information about an individual in such an interaction can be collected through the analysis of his or her neurophysiological and behavioral responses. We have developed a unique platform, the Empathy-Enhancing Virtual Evolving Environment (EEVEE), which is built around three main components: (1) different avatars capable of expressing feelings and emotions at various levels based on the Facial Action Coding System (FACS); (2) systems for measuring the physiological responses of the observer (heart and respiration rate, skin conductance, gaze and eye movements, facial expression); and (3) a multimodal interface linking the avatar's behavior to the observer's neurophysiological response. In this article, we provide a detailed description of the components of this innovative platform and validation data from the first phases of development. Our data show that healthy adults can discriminate different negative emotions, including pain, expressed by avatars at varying intensities. We also provide evidence that masking part of an avatar's face (top or bottom half) does not prevent the detection of different levels of pain. This innovative and flexible platform provides a unique tool to study and even modulate empathy in a comprehensive and ecological manner in various populations, notably individuals suffering from neurological or psychiatric disorders.Canadian Foundation for Innovation Natural Sciences and Engineering Research Council of Canada to PLJ Canadian Institutes of Health Research Fonds de recherche du Québec – Sant

Exposure to extremely low frequency electromagnetic fields alters the behaviour, physiology and stress protein levels of desert locusts

Electromagnetic fields (EMFs) are present throughout the modern world and are derived from many man-made sources including overhead transmission lines. The risks of extremely-low frequency (ELF) electromagnetic fields are particularly poorly understood especially at high field strengths as they are rarely encountered at ground level. Flying insects, however, can approach close to high field strength transmission lines prompting the question as to how these high levels of exposure affect behaviour and physiology. Here we utilise the accessible nervous system of the locust to ask how exposure to high levels of ELF EMF impact at multiple levels. We show that exposure to ELF EMFs above 4 mT leads to reduced walking. Moreover, intracellular recordings from an identified motor neuron, the fast extensor tibiae motor neuron, show increased spike latency and a broadening of its spike in exposed animals. In addition, hind leg kick force, produced by stimulating the extensor tibiae muscle, was reduced following exposure, while stress-protein levels (Hsp70) increased. Together these results suggest that ELF EMF exposure has the capacity to cause dramatic effects from behaviour to physiology and protein expression, and this study lays the foundation to explore the ecological significance of these effects in other flying insects

The perception and estimation of others’ pain according to children

Accurate interpretation of pain expressed by others is important for socialization; however, the development of this skill in children is still poorly understood. Empathy for pain models propose two main components (affective and cognitive), which develop at different stages of life. The study’s objective was to investigate the children’s ability between 3 and 12 years of age to detect and assess the pain intensity in others using visual stimuli depicting either facial expressions of pain or hands in painful contexts. 40 preschool children and 62 school-aged children were recruited. Children observed series of stimuli and evaluated the pain intensity depicted. Results demonstrated that children as young as three years old were able to detect and assess pain in both types of stimuli and this ability continued to improve until the age of 12. Participants demonstrated better detection performance with hands than with faces. Results were coherent with the idea that the two types of stimuli presented recruit different processes. Pain detection in hands appears to rely mostly on affective sharing processes that are effective early in life, while older children’s higher ability to perceive pain in facial expressions suggests that this ability is associated with the gradual development of cognitive processes

The Controversies and Difficulties of Diagnosing Primary Ciliary Dyskinesia

We welcome the correspondence from Lavie and Amirav (1), highlighting the difficulties diagnosing primary ciliary dyskinesia (PCD) and the role of high-speed video analysis (HSVA). As members of the European Respiratory Society (ERS) PCD Diagnostic Task Force (2) and/or large PCD Centres, we agree that HSVA has an important role that is not recognized by the American Thoracic Society (ATS) PCD Diagnostic Guideline (3). This risks a large proportion of false-negative “missed” diagnoses and a sizable number of false-positive cases; we make additional important observations.</div