Electromyogram Interference Reduction In Neural Signal Recording Using Simple RC Compensation Circuits

Neuroprosthesis can partially restore lost motor functionalities of individuals such as bladder voiding using functional electrical stimulation (FES) techniques. FES involves applying pattern of electrical current pulses using implanted electrodes to trigger affected nerves that are damaged due to paralysis. A neural signal recorded using tripolar cuff electrodes is significantly contaminated due to the presence of EMG interference from the surrounding muscles. Conventional neural amplifiers are unable to remove such interferences and modifications to the design are required. The modification to the design of the Quasi-tripole (QT) amplifier is considered in this work to minimise the EMG interferences from neural signal recording. The analogy between this modified version of QT known as mQT and Wheatstone bridge claims to neutralise the EMG interference by adding compensation circuit to either end of the outer electrodes of the tripolar cuff and therefore balancing the bridge. In this work, we present simple 3 and 2 stage RC compensation circuits to minimise EMG interference in trying to balance the bridge in the neural frequency band of interest (500-10kHz). It is shown that simple RC compensation circuit in series reduces EMG interference only at the spot frequency rather than linearly in the entire frequency band of interest. However, two and three stages RC ladder compensation circuits mimicking electrode-electrolyte interface, can minimize the EMG interference linearly in the entire frequency band of interest, without requiring any readjustment to their components. The aim is to minimise EMG interference as close to null as possible. Invitro testing of about 20% imbalanced cuff electrode with proposed 3 and 2 stage RC ladder compensation circuits resulted in linear EMG interference reduction atleast by a factor of 6. On an average, this yielded an improvement of above 80% EMG minimisation, in contrast to above 90% observed in the optimisation results, when 1Ω transimpedance (EMG) was introduced into the setup. Further improvements to the setup and design can give more promising results in reliable neural signal recording for FES applications

Neutralisation of myoelectric interference from recorded nerve signals using models of the electrode impedance

Any form of paralysis due to spinal cord injury or other medical condition, can have a significant impact on the quality and life expectancy of an individual. Advances in medicine and surgery have offered solutions that can improve the condition of a patient, however, most of the times an individual’s life does not dramatically improve. Implanted neuroprosthetic devices can partially restore the lost functionalities by means of functional electrical stimulation techniques. This involves applying patterns of electrical current pulses to innervate the neural pathways between the brain and the affected muscles/organs, while recording of neural information from peripheral nerves can be used as feedback to improve performance. Recording naturally occurring nerve signals via implanted electrodes attached to tripolar amplifier configurations is an approach that has been successfully used for obtaining desired information in non-acute preparations since the mid-70s. The neural signal (i.e. ENG), which can be exploited as feedback to another system (e.g. a stimulator), or simply extracted for further processing, is then intrinsically more reliable in comparison to signals obtained by artificial sensors. Sadly, neural recording of this type can be greatly compromised by myoelectric (i.e. EMG) interference, which is present at the neural interface and registered by the recording amplifier. Although current amplifier configurations reduce myoelectric interference this is suboptimal and therefore there is room for improvement. The main difficulty exists in the frequency-dependence of the electrode-tissue interface impedance which is complex. The simplistic Quasi-Tripole amplifier configuration does not allow for the complete removal of interference but it is the most power efficient because it uses only one instrumentation amplifier. Conversely, the True-Tripole and its developed automatic counterpart the Adaptive-Tripole, although minimise interference and provide means of compensating for the electrode asymmetries and changes that occur to the neural interface (e.g. due to tissue growth), they do not remove interference completely as the insignificant electrode impedance is still important. Additionally, removing interference apart from being dependent on the frequency of the interfering source, it is also subject to its proximity and orientation with respect to the recording electrodes, as this affects the field. Hence neutralisation with those two configurations, in reality, is not achieved in the entire bandwidth of the neural signal in the interfering spectrum. As both are less power efficient than the Quasi-Tripole an alternative configuration offering better performance in terms of interference neutralisation (i.e. frequency-independent, insensitive to the external interference fields) and, if possible, consume less power, is considered highly attractive. The motivation of this work is based on the following fact: as there are models that can mimic the frequency response of metal electrodes it should be possible, by constructing a network of an equivalent arrangement to the impedance of electrodes, to fit the characteristic neutralisation impedance – the impedance needed to balance a recording tripole – and ideally require no adjustment for removing interference. The validity of this postulation is proven in a series of in-vitro preparations using a modified version of the Quasi-Tripole made out of discrete circuit components where an impedance is placed at either side of the outer electrodes for balancing the recording arrangement. Various models were used in place of that impedance. In particular, representing the neutralisation impedance as a parallel RC reduced interference by a factor of 10 at all frequencies in the bandwidth of the neural signal while removed it completely at a spot frequency. Conversely, modelling the effect of the constant phase angle impedance of highly polarisable electrodes using a 20 stages non-uniform RC ladder network resulted in the minimisation of interference without the initial requirement of continuous adjustment. It is demonstrated that with a model that does not perfectly fit the impedance profile of a monopolar electrochemical cell an average reduction in interference of about 100 times is achieved, with the cell arranged as a Wheatstone bridge that can be balanced in the ENG band

Inflammation Inhibits Osteoblast-Mediated Bone Formation in Rheumatoid Arthritis and Regulates the Wnt and BMP Signaling Pathways: A Dissertation

Osteoclast-mediated focal articular bone erosion is a hallmark of rheumatoid arthritis, a disease of inflammation-induced bone loss. Inflammation in the bone microenvironment enhances osteoclast differentiation leading to bone erosion. Simultaneously, inflammation also inhibits osteoblast-mediated bone formation, further contributing to the net loss of bone. Previous studies have shown a paucity of mature osteoblasts at eroded bone surfaces correlating with suppression of bone formation and upregulation of antagonists of the Wnt pathway, a signaling cascade essential for osteoblast lineage commitment. Despite these observations, the exact pathogenesis of impaired bone formation in the setting of inflammation is not clearly understood. This dissertation aims to delineate the mechanisms by which inflammation suppresses osteoblast differentiation and activity in inflammatory arthritis. Specifically, this research elucidates how inflammation-induced alterations in the Wnt and bone morphogenetic protein (BMP) osteogenic signaling pathways contribute to bone loss and formation at distinct inflammatory microenvironments within the bone. Secondly, the means by which cellular mediators, including lymphocytes and macrophages, facilitate bone erosion and formation was addressed. Taken together, the research in this dissertation underscores the relationship between inflammation-induced bone loss and alterations in osteogenic signaling. Using an innovative murine inflammatory arthritis model, this study definitively demonstrates that resolving inflammation promotes osteoblast-mediated bone formation. Repair of erosions correlates with upregulation of synovial expression of Wnt10b, a Wnt agonist, and downregulation of sFRP1 and sFRP2, Wnt antagonists. This work also directly evaluates the contribution of sFRP1 to inflammation-induced bone destruction. Furthermore, this research demonstrates that expression of BMP3, a negative regulator of BMP signaling, is upregulated in osteoblasts by IL-17, a pro-inflammatory cytokine. BMP3-expressing osteoblasts are also observed at erosion sites in murine arthritis. Lastly, evaluation of the mediators of inflammation-induced periosteal bone formation implicates BMP2 as a means by which inflammation may positively regulate osteoblast function. This dissertation further elucidates the role of T cells and macrophages in the erosion and formation processes, respectively. In the absence of lymphocytes, bone erosion occurred normally, demonstrating that RANKL-expressing lymphocytes are not absolutely required for the bone erosion. Preliminary studies also suggest that M2 macrophages are potential mediators of bone formation via the expression of BMP2. In conclusion, this dissertation explores the ability of inflammation to act as a rheostat, which controls the fate of bone by modulating not only osteoclast differentiation, but also osteogenic signaling pathways and cellular mediators in the bone microenvironment. The soluble mediators and cell types identified in this research highlight novel mechanisms by which inflammation may regulate osteoblast activity within the bone microenvironment. Collectively, these data imply that strict control of inflammation may be necessary in order to create an anabolic environment that preserves bone architecture in diseases of inflammation-induced bone loss

XXII International Conference on Mechanics in Medicine and Biology - Abstracts Book

This book contain the abstracts presented the XXII ICMMB, held in Bologna in September 2022. The abstracts are divided following the sessions scheduled during the conference

Advances of Italian Machine Design

This 2028 Special Issue presents recent developments and achievements in the field of Mechanism and Machine Science coming from the Italian community with international collaborations and ranging from theoretical contributions to experimental and practical applications. It contains selected contributions that were accepted for presentation at the Second International Conference of IFToMM Italy, IFIT2018, that has been held in Cassino on 29 and 30 November 2018. This IFIT conference is the second event of a series that was established in 2016 by IFToMM Italy in Vicenza. IFIT was established to bring together researchers, industry professionals and students, from the Italian and the international community in an intimate, collegial and stimulating environment

Personality Identification from Social Media Using Deep Learning: A Review

Social media helps in sharing of ideas and information among people scattered around the world and thus helps in creating communities, groups, and virtual networks. Identification of personality is significant in many types of applications such as in detecting the mental state or character of a person, predicting job satisfaction, professional and personal relationship success, in recommendation systems. Personality is also an important factor to determine individual variation in thoughts, feelings, and conduct systems. According to the survey of Global social media research in 2018, approximately 3.196 billion social media users are in worldwide. The numbers are estimated to grow rapidly further with the use of mobile smart devices and advancement in technology. Support vector machine (SVM), Naive Bayes (NB), Multilayer perceptron neural network, and convolutional neural network (CNN) are some of the machine learning techniques used for personality identification in the literature review. This paper presents various studies conducted in identifying the personality of social media users with the help of machine learning approaches and the recent studies that targeted to predict the personality of online social media (OSM) users are reviewed

Twelfth Annual Conference on Manual Control

Main topics discussed cover multi-task decision making, attention allocation and workload measurement, displays and controls, nonvisual displays, tracking and other psychomotor tasks, automobile driving, handling qualities and pilot ratings, remote manipulation, system identification, control models, and motion and visual cues. Sixty-five papers are included with presentations on results of analytical studies to develop and evaluate human operator models for a range of control task, vehicle dynamics and display situations; results of tests of physiological control systems and applications to medical problems; and on results of simulator and flight tests to determine display, control and dynamics effects on operator performance and workload for aircraft, automobile, and remote control systems

A reconceptualization of anxiety

The aim of the thesis is three fold: a-To develop a new questionnaire that measures anxiety in terms of four components (feeling, cognitive, behavior and somatic). b-To investigate the relationship between feeling and cognition with regard to anxiety. c-To identify, with the application of Three Systems Theory, the most salient component of anxiety in each of the DSM-III anxiety disorder sub-classifications and to evaluate the validity of DSM-III anxiety disorder sub-classifications. a-In order to assess the level of anxiety, I have developed a new Four Systems Anxiety Questionnaire (FSAQ). FSAQ incorporates a feeling component along with the behavioral, somatic and cognitive components. A psychometric evaluation (reliability and validity levels) of the questionnaire was found to be satisfactory. b-Another aim is to reconsider one of the tenets of cognitive therapy that cognitive appraisals are the necessary preconditions for the emergence of feeling. Such a view assumes that feeling is merely an epiphenomenon of cognitive processes. This research establishes, however, that feeling and cognition appear to be relatively independent systems and that their modes of interaction are influenced by the personality structure of the individual. This conclusion was obtained by using the FSAQ on university students and various categories of anxiety patients. In particular, the research compared the scores on the feeling and cognitive components of both males and females, obsessive-compulsives and rest of the DSM-III anxiety patients. c- A further aim of the reseach was to examine the DSM-III anxiety disorders classification from the Three Systems Theory's point of view. The Three Systems Theory proposes that anxiety has three relatively independent components: cognitive, behavioral and somatic. In the various anxiety sub-classifications of DSM-III one or other of these three components dominates. The other purpose of my research was to consider each of the DSM-III anxiety disorders separately and to determine which of the three components plays the major role in the manifestation of the particular syndrome. In general, the results indicate that each anxiety disorder is indeed characterised by a different profile. An anticipated outcome of this research is that a clinician will be able to identify the main component of anxiety in a particular syndrome and hence select most appropriate treatment. The results of this study support DSM-III classification of anxiety disorders into two main categories of phobic and non-phobic (i.e. phobic and anxiety states)

Life Sciences Program Tasks and Bibliography for FY 1996

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1996. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web page

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag