Multiscale body maps in the human brain

A large number of brain regions are dedicated to processing information from the body in order to enable interactions with the environment. During my thesis, I studied the functional organization of brain networks involved in processing bodily information. From the processing of unimodal low-level features to the unique experience of being a unified entity residing in a physical body, the brain processes and integrates bodily information at many different stages. Using ultra high-field functional Magnetic Resonance Imaging (fMRI), I conducted four studies to map and characterize multiscale body representations in the human brain. The goals of my thesis were first to extend the actual knowledge about primary sensorimotor representations, and second to develop novel approaches to investigate more complex and integrated forms of body representations. In studies I and II, I first investigated how natural touch was represented in the three first cortical areas processing tactile information. I applied a mapping procedure to identify in each of these three areas the somatosensory representations of 24 different body parts on hands, feet and legs at the level of single subjects. Using fMRI and resting-state data, I combined classical statistical analyses with modern methods of network analysis to describe the functional properties of the formed network. In study III, I applied these methods to investigate primary somatosensory and motor representations in a rare population of patients. Following limb loss, the targeted muscle and sensory reinnervation (TMSR) procedure enables the intuitive control of a myoelectric prosthesis and creates an artificial map of referred touch on the reinnervated skin. I mapped the primary somatosensory and motor representations of phantom sensations and phantom movements in TMSR patients. I investigated whether sensorimotor training enabled via TMSR was associated with preserved somatosensory and motor representations compared to healthy controls and amputee patients without TMSR. Finally in study IV, I studied brain regions involved in the subjective body experience. Following specific manipulations of sensorimotor information, it is possible to let participants experience a fake or virtual hand as their own and to give them the sensation of being in control of this hand. Using MR-compatible robotics and virtual reality, I investigated the brain regions associated with the alteration of the sense of hand ownership and the sense of hand agency. The present work provides important findings and promising tools regarding the understanding of brain networks processing bodily information. In particular, understanding the functional interactions between primary unimodal cortices and networks contributing to subjective body experience is a necessity to promote modern approaches in the fields of neuroprosthetic and human-machine interactions

Changes in Heart Rate Variability Recorded in Natural Situation with T-Shirt Integrated Sensors and Level of Observed Behavioral Excitation: A Pilot Study of Patients with Intellectual Disabilities and Psychiatric Disorders.

The present study investigates the possibilities of using heart rate variability (HRV) parameters as physiological markers that precede increase in observed behavioral excitation of intellectually disabled individuals. The ability to recognize or predict such patterns, especially in patients showing unpredictable reactions and language deficiencies, might be a major step forward in clinical research. Thirteen volunteers with intellectual disabilities, who had suffered of at least one event of overt aggression in the preceding 3 months, participated to the study. The protocol consists in the acquisition of continuous electrocardiogram (ECG) throughout approximately two times of 8 h in natural situation, using a T-shirt integrated with sensors. Simultaneously, an observer evaluates the patient's level of overt excitation from calm (level 1) to extremely tense (level 5) and send online via Bluetooth these triggers into the ECG signals. The HRV indexes were then estimated offline on the basis of the inter-beat intervals recorded by the ECG, independently for the 30 min preceding each behavioral tension marking point, averaged, and compared through non-parametric Wilcoxon matched-pairs test. Of these, the RMSSD and LF/HF calculations were used to observe the fluctuations of inhibitory activity and cardiovagal balance through different tension states. Seven individuals have sufficient reliable data for analysis. They have reached at least a level 3 of behavioral excitation (moderately tense) or more (very to extremely tense, level 4 and 5) and have been retained for further analysis. In sum, a total of 197 periods of tension were kept, made up of 46 periods of slight excitation (level 2), 18 of moderate excitation (level 3), 10 of high excitation (level 4), and 5 of extreme agitation (level 5). Variations in the HRV as a function of degree of excitation are observed for RMSSD index only (inhibitory parasympathetic activity). The changes from calm to increasing levels of excitation are characterized by a significant downfall in RMSSD index when patients were evaluated to be in a very high level of tension (level 4). The presence of precursors to agitation, reflected in the falling-off of parasympathetic activity, offers potentially interesting prospects for therapeutic development

Vibration Problems Of Large Vertical Pumps And Motors

LectureA large vertical pump with its associated motor driver constitutes a very complex dynamic system. The apparent simplicity of the visible cantilever portion of the machine belies the complex interaction of the unit with its piping, foundation, soil and process fluid, all of which must be considered in order to achieve a successful design. This system approach is presented in this paper by an analytical and experimental study of a 3000 hp crude oil loading pump. The study shows the large number of possible vibrational modes which can exist near the operational speed of a typical system and the factors which should be considered in predicting resonant frequencies. Also included in the paper are several case histories which illustrate some of the dynamic problems which are common to vertical machines

Contribution of interaction force to the sense of hand ownership and the sense of hand agency

When performing willed actions, we have the unified and coherent experience of owning and controlling our body. Body ownership is believed to emerge from the integration of coherent multisensory signals, while agency is believed to emerge from the coherence between predicted and perceived outcomes of actions. As a consequence, body ownership and agency can both be modulated by multisensory conflicts. The contribution of active movement generation to ownership and agency has not been parametrically explored. Here, we investigated the contribution of interaction force between the agent and the environment to the sense of hand ownership (SO) and the sense of hand agency (SA). By combining robotics and virtual reality, we manipulated the sensorimotor and visual information during immersive scenarios to induce and quantify altered states of SO and SA. First, we demonstrated that SO and SA could be successfully manipulated by our experimental paradigms. Second, we showed that interaction force strongly contributes to SA, but to a lesser extent to SO. Finally, we showed that SO and SA interact beyond their common multisensory basis. Our results, based on two independent studies, provide a direct link between sensorimotor interactions and subjective body experience and demonstrate a new dissociation between SO and SA.ISSN:2045-232

Upper limb cortical maps in amputees with targeted muscle and sensory reinnervation

‘Targeted motor and sensory reinnervation' (TMSR) entails rerouting residual limb nerves towards intact muscles and skin to try to achieve prostheses that move and feel like real limbs. Using ultra-high field 7T fMRI, Serino et al. examine upper limb representations in M1 and S1 of amputees who have undergone TMSR

Robot-induced hallucinations in Parkinson’s disease depend on altered sensorimotor processing in fronto-temporal network

International audienceHallucinations in Parkinson’s disease (PD) are disturbing and frequent non-motor symptoms and constitute a major risk factor for psychosis and dementia. We report a robotics-based approach applying conflicting sensorimotor stimulation, enabling the induction of presence hallucinations (PHs) and the characterization of a subgroup of patients with PD with enhanced sensitivity for conflicting sensorimotor stimulation and robot-induced PH. We next identify the fronto-temporal network of PH by combining MR-compatible robotics (and sensorimotor stimulation in healthy participants) and lesion network mapping (neurological patients without PD). This PH-network was selectively disrupted in an additional and independent cohort of patients with PD, predicted the presence of symptomatic PH, and associated with cognitive decline. These robotics-neuroimaging findings extend existing sensorimotor hallucination models to PD and reveal the pathological cortical sensorimotor processes of PH in PD, potentially indicating a more severe form of PD that has been associated with psychosis and cognitive decline

Sensorimotor hallucinations in Parkinson's Disease

Hallucinations in Parkinson’s disease (PD) are one of the most disturbing non-motor symptoms, affect half of the patients, and constitute a major risk factor for adverse clinical outcomes such as psychosis and dementia. Here we report a robotics-based approach, enabling the induction of a specific clinically-relevant hallucination (presence hallucination, PH) under controlled experimental conditions and the characterization of a PD subgroup with enhanced sensorimotor sensitivity for such robot-induced PH. Using MR-compatible robotics in healthy participants and lesion network mapping analysis in neurological non-PD patients, we identify a fronto-temporal network that was associated with PH. This common PH-network was selectively disrupted in a new and independent sample of PD patients and predicted the presence of symptomatic PH. These robotics-neuroimaging findings determine the behavioral and neural mechanisms of PH and reveal pathological cortical sensorimotor processes of PH in PD, identifying a more severe form of PD associated with psychosis and cognitive decline