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La bioélectronique est un domaine interdisciplinaire qui étudie les interconnexions et les interactions entre entités biologiques (cellules, tissus, organes) et systèmes électroniques,par l’intermédiaire du transducteur adéquat. Pour des cellules ou des tissus excitables (neurones, muscles, ...), le transducteur prend la forme d’une simple électrode, car ces tissus produisent une activité électrique spontanée ou, dans le sens inverse, peuvent être excités par un signal électrique externe. Cette communication bidirectionnelle donne lieu à deux schémas expérimentaux : l’acquisition et la stimulation. L’acquisition consiste à enregistrer, traiter et analyser les bio-signaux alors que la stimulation consiste à appliquer le courant électrique adéquat aux tissus vivants, pour déclencher une réaction. Cette thèse se concentre sur ce dernier point : deux générations de système de stimulation ont été développées, chacune basée sur un circuit intégré spécifique et adaptée à différents contextes applicatifs.Tout d’abord, le cadre scientifique a été celui du projet CENAVEX, axé sur la stimulation électrique fonctionnelle pour réhabiliter la fonction respiratoire, suite à une lésion de la moelle épinière. Ensuite, les objectifs de conception ont été étendus pour couvrir de nouveaux besoins d’application : la surveillance de l’impédance électrique in situ et l’exploration des formes d’onde de stimulation originales. Le premier pourrait être une solution pour suivre la réaction tissulaire après l’implantation d’une électrode, contribuant ainsi à la biocompatibilité à long terme des implants ; le second propose d’aller au-delà dela conventionnelle impulsion biphasique carrée et d’explorer de nouvelles formes d’ondes qui pourraient être plus efficaces en termes de consommation d’énergie, pour un effet physiologique donné.Le travail présenté dans ce manuscrit contribue à la conception, à la fabrication et au test de dispositifs de stimulation innovants. Cela a conduit au développement de deux circuits intégrés et de deux dispositifs de stimulation permettant une stimulation multicanal.Les caractérisations électriques et les validations biologiques, de la faisabilité in vitro aux expériences in vivo, ont été menées et sont décrites dans ce manuscrit. / Bioelectronics is a cross-disciplinary field that studies interconnections and interactions between biological entities (cells, tissues, organs) and electronic systems, using the adequate transducer. For excitable cells or tissues (neurons, muscles, . . . ), the transducer takes the form of a simple electrode, as these tissues produce a spontaneous electrical activity or,in the opposite way, may be excited by an external electrical signal. This bi-directional communication gives rise to two experimental schemes: acquisition and stimulation. Acquisition consists in recording, processing and analyzing bio-signals whereas stimulation consists in applying the adequate electrical current to living tissues in order to trigger a reaction. This thesis focuses on the latter: two generations of stimulation systems have been developed, both being centered on an Application Specific Integrated Circuit, and adapted to different application contexts. First, the scientific framework was given by the CENAVEX project, focusing on Functional Electrical Stimulation to rehabilitate the respiratory function, following a Spinal Cord Injury. Then, the design objectives were extended to cover new application needs:in situ electrical impedance monitoring and exploration of original stimulation wave forms.The first one could be a solution to follow the tissue reaction after electrode implantation,hence contributing to long-term biocompatibility of implants; the second one proposes to go further the conventional constant biphasic pulse and explore new wave forms that couldbe most efficient in terms of energy consumption, for a given physiological effect.The work presented in this manuscript is a contribution to the design, fabrication and test of innovative stimulation devices. It leaded to the development of two integrated circuits and two stimulation devices permitting multichannel stimulation. Both electrical characterizations and biological validations, from in vitro feasibility to in vivo experiments, have been conducted and are described in this manuscript.

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Spreading depression (SD) is a slow propagating wave of depolarization that can spread throughout the cortex in the event of brain injury or any general energy failure of the brain. Massive cellular depolarization causes enormous ionic and water shifts and silences synaptic transmission in the affected tissue. Large amounts of energy are required to restore ionic gradients and are not always met. When these energetic demands are not met, brain tissue damage can occur. The exact mechanism behind initiation and propagation of SD are unknown, but a general model is known. It may be possible to prevent or delay the onset of SD using non-invasive electromagnetic techniques. Transcranial magnetic stimulation (TMS), electrical stimulation (ES), and transcranial direct coupled stimulation (tDCS) could be used to decrease neuronal excitability in different ways. In theory, any technique that can reduce cortical excitability could suppress SD initiating or propagating.

No description available.

The effects of cranial electrotherapy stimulation (CES) on human EEG and brain current density were evaluated by quantitative electroencephalography (qEEG) and low resolution brain electromagnetic tomography (LORETA). A total of 72 research subjects were provided with a single session of CES, 38 were provided with 0.5 Hz CES while 34 were provided with 100 Hz CES. The qEEG paired t-tests revealed that in both frequencies of CES there was a significant (.05) increase in alpha relative power with concomitant decreases in delta and beta relative power. The 0.5 Hz CES decreased a wider frequency range of delta activity, while the 100 Hz CES decreased a wider frequency range of beta activity; suggesting some difference may exist in the EEG response to different frequencies of CES. The changes found in qEEG relative power were consistent with the affective and cognitive effects of CES reported in the literature, such as increased relaxation and decreased anxiety. Statistically significant changes for qEEG values other than relative power, such as coherence, amplitude asymmetry, phase lag and power ratios were also found. The LORETA paired t-tests found statistically significant (.05) increases in cortical and subcortical theta and alpha frequency current density with concomitant decreases in delta and beta current density. The effects of CES on current density varied by frequency, but did not show a differential in response based on proximity to the contacts, or structures within the brain. Statistically significant changes in current density were found in all 2394 gray matter voxels represented by LORETA, indicating a whole brain response to the CES stimulus. The qEEG and LORETA findings revealed that a single 20-minute session of CES does have a significant effect on the cortical and subcortical activity of the human brain resulting in activity consistent with decreased anxiety and increased relaxation.

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The well-known field of engineering psychology, also known as human factors engineering, utilizes psychologists to solve Engineering's problems that concern the behavior of humans in their operation and control of engineering systems such as military aircraft. To limit psychology's relation to engineering this way is, however, counterproductive. Psychology requires a broader conceptualization of engineering psychology, a subfield of psychology, within which the psychologist's major concern is with the behavior of psychoengineering systems that affect the reliability, validity and safety of psychological research and practice. In contrast with human-factor systems, the psychoengineering systems include healthy and unhealthy, human and animal subjects. The affiliated problems are not those of the engineering industry. This study in engineering psychology concerned the safety of two electrical stimulation systems that are used on animals, chiefly dogs, in punishment and escape/avoidance conditioning procedures of psychology. The study referenced two safety questions. First, is the electricity, when applied externally to the ventral neck of the animal, capable of stimulating carotide sinus and vagus nerves to the point of dangerously disrupting systemic blood pressure and sinus rhythm? Second, is the electricity capable of damaging the epidermis when it is applied repeatedly to the same two points of contact? Of forty-two anesthetized dogs, half were tested with a punishment system; the remainder were tested with an escape/avoidance system. Each was stimulated for five seconds, five times, at each of five intensities. Inter-stimulus interval was about thirty seconds. Systemic blood pressures and electrocardiograms (ECG) were recorded. Control and experimental biopsies were taken for histological examinations of electrified and unelectrified specimens. Each animal's neck was examined grossly each day for ten days following the stimulation runs. None of the gross examination reports was positive. An exact binomial test supported the hypothesis that tissue samples from control and experimental biopsies did not differ histologically. Repeated measure ANOVAs were used to detect significant differences in systolic pressures, diastolic pressures, and R to R intervals of the ECG throughout stimulation runs. While there were some statistically significant results, there was no clinical significance, especially with regard to safety hazards.

Previous research and current models have proposed that the right temporoparietal junction (rTPJ) is crucially involved in the control and distinction of shared representations of action. Hitherto, this assumption has mainly been based on neuroimaging work ( (Spengler, von Cramon, & Brass, 2009); (Spengler, von Cramon, & Brass, 2010)) We tested this hypothesis, that the rTPJ is causally involved in managing shared representations by using repetitive transcranial magnetic stimulation in an offline paradigm to disrupt neural activity in this region. Using a simple imitation-inhibition task we showed that stimulation of the rTPJ led to increased reaction times when participants had to control automatic imitation of a perceived hand movement, as they had to concurrently plan and execute an opposite movement. Our study provides the first empirical evidence that the rTPJ is necessary for managing and navigating within a shared representational system. These results may also have important implications for future theorizing about the role of the TPJ region in controlling shared representations also in other domains, such as somatosensation or emotional experiences.