Neural correlates of bilateral proprioception and adaptation with training

Bilateral proprioception includes the ability to sense the position and motion of one hand relative to the other, without looking. This sensory ability allows us to perform daily activities seamlessly, and its impairment is observed in various neurological disorders such as cerebral palsy and stroke. It can undergo experience-dependent plasticity, as seen in trained piano players. If its neural correlates were better understood, it would provide a useful assay and target for neurorehabilitation for people with impaired proprioception. We designed a non-invasive electroencephalography-based paradigm to assess the neural features relevant to proprioception, especially focusing on bilateral proprioception, i.e., assessing the limb distance from the body with the other limb. We compared it with a movement-only task, with and without the visibility of the target hand. Additionally, we explored proprioceptive accuracy during the tasks. We tested eleven Controls and nine Skilled musicians to assess whether sensorimotor event-related spectral perturbations in μ (8-12Hz) and low-β (12-18Hz) rhythms differ in people with musical instrument training, which intrinsically involves a bilateral proprioceptive component, or when new sensor modalities are added to the task. The Skilled group showed significantly reduced μ and low-β suppression in bilateral tasks compared to movement-only, a significative difference relative to Controls. This may be explained by reduced top-down control due to intensive training, despite this, proprioceptive errors were not smaller for this group. Target visibility significantly reduced proprioceptive error in Controls, while no change was observed in the Skilled group. During visual tasks, Controls exhibited significant μ and low-β power reversals, with significant differences relative to proprioceptive-only tasks compared to the Skilled group-possibly due to reduced uncertainty and top-down control. These results provide support for sensorimotor μ and low-β suppression as potential neuromarkers for assessing proprioceptive ability. The identification of these features is significant as they could be used to quantify altered proprioceptive neural processing in skill and movement disorders. This in turn can be useful as an assay for pre and post sensory-motor intervention research.

Impedance Control of a 2-DOF Spherical 5-Bar Exoskeleton for Physical Human-Robot Interaction During Rehabilitation and Assessment

This paper presents a novel impedance controller for THINGER (THumb INdividuating Grasp Exercise Robot), a 2-degree-of-freedom (DOF) spherical 5-bar exoskeleton designed to augment FINGER (Finger INdividuating Grasp Exercise Robot). Many rehabilitation and assessment tasks, for which THINGER is designed, are improved by rendering near-zero impedance during physical human-robot interaction (pHRI). To achieve this goal, the presented impedance controller includes several novel features. First, a reference trajectory is omitted, allowing free movements. Second, force-feedback gains are reduced near actuator limits and a saturation function limits the maximum commanded force; both allow more responsive (higher) force-feedback gains within the workspace and mitigate transient oscillations caused by external disturbances. Finally, manipulability-based directional force-feedback gains help improve rendered impedance isotropy. Validation experiments included free exploration of the workspace, following a prescribed circular thumb motion, and intentional exposure to external disturbances. The experimental results show that the presented impedance controller significantly reduces impedance to subject-initiated motion and accurately renders the desired isotropic low-impedance environment.

Comparison of Admittance Control Dynamic Models for Transparent Free-Motion Human-Robot Interaction

This paper presents an experimental comparison of multiple admittance control dynamic models implemented on a five-degree-of-freedom arm exoskeleton. The performance of each model is evaluated for transparency, stability, and impact on point-to-point reaching. Although ideally admittance control would render a completely transparent environment for physical human-robot interaction (pHRI), in practice, there are trade-offs between transparency and stability-both of which can detrimentally impact natural arm movements. Here we test four admittance modes: 1) Low-Mass: low inertia with zero damping; 2) High-Mass: high inertia with zero damping; 3) Velocity-Damping: low inertia with damping; and 4) a novel Velocity-Error-Damping: low inertia with damping based on velocity error. A single subject completed two experiments: 1) 20 repetitions of a single reach-and-return, and 2) two repetitions of reach-and-return to 13 different targets. The results suggest that the proposed novel Velocity-Error-Damping model improves transparency the most, achieving a 70% average reduction of vibration power vs. Low-Mass, while also reducing user effort, with less impact on spatial/temporal accuracy than alternate modes. Results also indicate that different models have unique situational advantages so selecting between them may depend on the goals of the specific task (i.e., assessment, therapy, etc.). Future work should investigate merging approaches or transitioning between them in real-time.

Design and Development of a Spherical 5-Bar Thumb Exoskeleton Mechanism for Poststroke Rehabilitation

This paper presents the kinematic design and development of a two degree-of-freedom (2DOF) spherical 5-bar thumb exoskeleton to augment the finger individuating grasp exercise robot (FINGER) rehabilitation robot, which assists the index and middle fingers individually in naturalistic grasping. The thumb module expands the capabilities of FINGER, allowing for broader proprioceptive training and assessment of hand function. The design process started by digitizing thumb-grasping motions to the index and the middle fingers separately, recorded from multiple healthy subjects utilizing a motion capture system. Fitting spheres to trajectory data of each subject allowed normalization of all subjects' data to a common center and radius. A two-revolute joint serial-chain mechanism was synthesized (intermediate optimization step) to reach the normalized trajectories. Next, the two resulting grasping trajectories were spatially sampled as targets for the 2DOF spherical 5-bar synthesis. Optimization of the spherical 5-bar included symmetry constraints and cost-function penalties for poor manipulability. The resulting exoskeleton assists both flexion/extension and abduction/adduction of the thumb enabling a wide range of motions. Consistent with FINGER, the parallel structure of the spherical 5-bar places the actuators at the base of the module, allowing for desirable characteristics, including high backdrivability, high controllable bandwidth, and low mechanical impedance. The mechanical design was developed from the kinematic solution, including an adjustable thumb cuff to accommodate different hand sizes. Fit and function of the device were tested on multiple subjects, including survivors of stroke. A proportional-derivative force controller with gravity and friction compensation was implemented to reduce resistance to motion during subject testing.

Literature review of stroke assessment for upper-extremity physical function via EEG, EMG, kinematic, and kinetic measurements and their reliability

BACKGROUND

Significant clinician training is required to mitigate the subjective nature and achieve useful reliability between measurement occasions and therapists. Previous research supports that robotic instruments can improve quantitative biomechanical assessments of the upper limb, offering reliable and more sensitive measures. Furthermore, combining kinematic and kinetic measurements with electrophysiological measurements offers new insights to unlock targeted impairment-specific therapy. This review presents common methods for analyzing biomechanical and neuromuscular data by describing their validity and reporting their reliability measures.

METHODS

This paper reviews literature (2000-2021) on sensor-based measures and metrics for upper-limb biomechanical and electrophysiological (neurological) assessment, which have been shown to correlate with clinical test outcomes for motor assessment. The search terms targeted robotic and passive devices developed for movement therapy. Journal and conference papers on stroke assessment metrics were selected using PRISMA guidelines. Intra-class correlation values of some of the metrics are recorded, along with model, type of agreement, and confidence intervals, when reported.

RESULTS

A total of 60 articles are identified. The sensor-based metrics assess various aspects of movement performance, such as smoothness, spasticity, efficiency, planning, efficacy, accuracy, coordination, range of motion, and strength. Additional metrics assess abnormal activation patterns of cortical activity and interconnections between brain regions and muscle groups; aiming to characterize differences between the population who had a stroke and the healthy population.

CONCLUSION

Range of motion, mean speed, mean distance, normal path length, spectral arc length, number of peaks, and task time metrics have all demonstrated good to excellent reliability, as well as provide a finer resolution compared to discrete clinical assessment tests. EEG power features for multiple frequency bands of interest, specifically the bands relating to slow and fast frequencies comparing affected and non-affected hemispheres, demonstrate good to excellent reliability for populations at various stages of stroke recovery. Further investigation is needed to evaluate the metrics missing reliability information. In the few studies combining biomechanical measures with neuroelectric signals, the multi-domain approaches demonstrated agreement with clinical assessments and provide further information during the relearning phase. Combining the reliable sensor-based metrics in the clinical assessment process will provide a more objective approach, relying less on therapist expertise. This paper suggests future work on analyzing the reliability of metrics to prevent biasedness and selecting the appropriate analysis.

3D Scanning of the Forearm for Orthosis and HMI Applications

The rise of rehabilitation robotics has ignited a global investigation into the human machine interface (HMI) between device and user. Previous research on wearable robotics has primarily focused on robotic kinematics and controls but rarely on the actual design of the physical HMI (pHMI). This paper presents a data-driven statistical forearm surface model for designing a forearm orthosis in exoskeleton applications. The forearms of 6 subjects were 3D scanned in a custom-built jig to capture data in extreme pronation and supination poses, creating 3D point clouds of the forearm surface. Resulting data was characterized into a series of ellipses from 20 to 100% of the forearm length. Key ellipse parameters in the model include: normalized major and minor axis length, normalized center point location, tilt angle, and circularity ratio. Single-subject (SS) ellipse parameters were normalized with respect to forearm radiale-stylion (RS) length and circumference and then averaged over the 6 subjects. Averaged parameter profiles were fit with 3rd-order polynomials to create combined-subjects (CS) elliptical models of the forearm. CS models were created in the jig as-is (CS1) and after alignment to ellipse centers at 20 and 100% of the forearm length (CS2). Normalized curve fits of ellipse major and minor axes in model CS2 achieve R² values ranging from 0.898 to 0.980 indicating a high degree of correlation between cross-sectional size and position along the forearm. Most other parameters showed poor correlation with forearm position (0.005 < R² < 0.391) with the exception of tilt angle in pronation (0.877) and circularity in supination (0.657). Normalized RMSE of the CS2 ellipse-fit model ranged from 0.21 to 0.64% of forearm circumference and 0.22 to 0.46% of forearm length. The average and peak surface deviation between the scaled CS2 model and individual scans along the forearm varied from 0.56 to 2.86 mm (subject averages) and 3.86 to 7.16 (subject maximums), with the peak deviation occurring between 45 and 50% RS length. The developed equations allow reconstruction of a scalable 3D model that can be sized based on two user measures, RS length and forearm circumference, or based on generic arm measurements taken from existing anthropometric databases.

Gravity Compensation of an Exoskeleton Joint Using Constant-Force Springs

Stroke is one of the leading causes of impairment in the world. Many of those who have suffered a stroke experience long-term loss of upper-limb function as a result. BLUE SABINO is an exoskeleton device being developed at the University of Idaho to help assess these patients and aid in their rehabilitation. One of the central design challenges with exoskeletons is limiting the overall weight of the device. Motors used in actuation of these devices are often oversized to allow gravity balancing of the device and user and the creation of torques to facilitate patient movements. If the torques required for gravity balancing are achieved through elastic elements, the motor and other upstream components can be lighter, potentially greatly reducing the overall weight of the device. In this paper, constant-force springs may provide an effective method of generating a constant offsetting torque to compensate for gravity. In experimental testing of multiple mounting configurations of C-shaped constant-force springs (single, back-to-back, double-wrapped), the force output fluctuated less than 8.6% over 180° of wrapping, with friction values below 2.6%, validating the viability of constant-force springs for this application. The results suggest the back-to-back configuration provides a simpler implementation with better force consistency while the double-wrapped configuration adds less friction to the system.

Energy Density and Hysteresis Comparison in Natural Rubber Tube Springs for Wearable Exoskeleton Applications

Wearable exoskeletons show promise as a means for compensating lost function as well as for providing optimal assistance for maximal therapeutic benefit during everyday tasks. Development of lightweight spring systems for efficient storage and return are proposed as a key component in the successful deployment of wearable exoskeletons for individuals with neurological deficits. Both spring steel and natural rubber are common materials used in energy storage, but have not been directly compared by metrics such as energy storage density, energy storage efficiency, and hysteresis. In this work, we perform cyclic loading tests on spring steel extension springs of varying wire diameter and natural rubber tubing of varying wall thicknesses. We then use measured load-extension profiles to illustrate and compute metrics to better quantify the energy storing capabilities of each material and their appropriateness for use as energy storing and returning components in wearable robotic applications. Results show that natural rubber has a higher capacity for energy storage per unit weight in comparison to steel springs. Hysteresis is also higher in natural rubber and can be dramatically reduced by applying adequate pre-strain at levels greater than the anticipated strain during use.

Mapping ADL Motion Capture Data to BLUE SABINO Exoskeleton Kinematics and Dynamics

Design of an upper-arm exoskeleton requires knowledge of human operational ranges and workspace distributions. Motion capture recordings of right-arm motion during common tasks, known as activities of daily living (ADLs), are taken to represent a plausible workspace for an exoskeleton. An inverse kinematic model of BLUE SABINO (BiLateral Upper-extremity Exoskeleton for Simultaneous Assessment of Biomechanical and Neuromuscular Output), driven by ADL data is established to map right-arm joint locations to exoskeleton motor joint space. A kinematic representation of a human right-arm driven by ADL data is implemented via a vector analysis utilizing quaternion rotation/translation and used to visualize ADL recordings. A model of the BLUE SABINO exoskeleton whose motion is driven by the mapped motorjoint-space data is used to validate the mapping graphically. The available ADL database is mapped to motor joint space. Motor position distributions are generated from the resulting dataset and estimates of robot range of motion, (ROM) and statistics for shoulder motor positions are established. A kinematically and inertially accurate model of the BLUE SABINO is developed by exporting SolidWorksOR part models into SimScape Multibody (MathWorks). The model is used to produce operational torque estimates for shoulder motors. Initial simulations indicate that the motors of interest have been properly sized.

Design parameters and torque profile modification of a spring-assisted hand-opening exoskeleton module

There is a growing demand for functional rehabilitation orthotics that can effectively assist in patient recovery from motor impairments after stroke. The hand in particular is a complex system that has proven difficult to mimic with current exoskeleton technologies. This paper presents data-driven design parameters to increase the functionality and improve the assistance profile of the ArmAssist-2.0 hand module. Improvements from the previous model include adjustable linkages to fulfill the largest population of users, new joint locations to more accurately represent biomechanics of the hand, and a more impairment-appropriate torque profile to assist in hand opening, adjustable through interchangeable springs. In most passive hand orthoses, assistance forces tend to decrease as the hand and thumb extend, opposite the needs of a typical patient hand. This project utilizes a variable spring moment arm about the revolute axes to match common patient impairment more accurately. The revised assistance profile for the hand maintains a nearly linear relationship. Results conclude that the final assembled device fits comfortably in the hand with noticeable improvements in joint locations, adjustability, and the force profile for the metacarpophalangeal (MCP) joint. An issue arises with the extension of the proximal interphalangeal (PIP) joint due to the nature of rapidly changing moment arms and multiple springs in series. The issue and possible solutions are discussed.

Development of a series wrapping cam mechanism for energy transfer in wearable arm support applications

An estimated 17 million individuals suffer a stroke each year with over 5 million resulting in permanent disability. For many of these, the provision of gravity support to the impaired upper limb can provide significant and immediate improvement in arm mobility. This added mobility has the potential to improve arm function and user independence overall, but, so far, wearable arm supports have found only limited uptake by end-users. The reasons are unclear, but it is hypothesized that device uptake is strongly affected by aspects of arm support implementation such as added weight and volume and the effectiveness of the support provided. In the interest of reducing the size and visibility of wearable arm supports, cable driven actuation was investigated, and a device called the series wrapping cam was developed. This device uses two wrapping cams to stretch a spring as the user's arm elevation decreases. It optimally uses the range of motion of a custom latex spring in a compact mechanism. A one degree-of-freedom proof-of-concept prototype of the series wrapping cam was manufactured and tested. The torque supplied by the prototype correctly responds to shoulder elevation to balance the weight of the extended arm at any level of elevation. However, the support is unaffected by the degree of elbow flexion-extension. Shoulder joint torque is a function of both shoulder elevation and elbow flexion, suggesting further benefits could be achieved through a bi-articular design.

Design of a spring-assisted exoskeleton module for wrist and hand rehabilitation

This paper reports on the development of a low-profile exoskeleton module to enable training of the fingers and thumb in grasp and release tasks. The design has been made as an add-on module for use with the ArmAssist arm rehabilitation system (Tecnalia, Spain). Variable-position springs and adjustable link lengths provide adaptability to fit a variety of users. Additive manufacturing has been utilized for the majority of components allowing easy modifications. A few structural components were machined from aluminum or steel to produce a functional prototype with sufficient strength for direct evaluation. The design includes independent and adjustable assistance in finger and thumb extension using various width elastic bands, and measurement of user grasp/release forces in finger flexion/extension, thumb flexion/extension, and thumb adduction/abduction using low-profile force sensitive resistors.

Design and optimization of PARTNER: a parallel actuated robotic trainer for NEuroRehabilitation

Robotic devices are a promising and dynamic tool in the realm of post-stroke rehabilitation. Researchers are still investigating how the use of robots affects motor learning and what design characteristics best encourage recovery. We present a parallel-actuated, end-effector robot designed to provide spatial assistance for upper-limb therapy while exhibiting low impedance and high backdrivability. A gradient based optimization was performed to find an optimal design that accounted for force isotropy, mechanical advantage, workspace size, and counter-balancing. A beta prototype has been built to these specifications (low impedance and high backdrivability) and has undergone initial controller performance as well as fit and function testing. By fitting a nonlinear model to experimental frequency response data, the apparent mass, viscous friction coefficient, and dynamic dry friction coefficient were determined to be 0.242 kg, 0.114 Ns/m, and 0.894 N respectively. The robot will serve as a testing platform to investigate motor learning and evaluate the efficacy of control schemes for post-stroke movement therapy.

Design of a thumb module for the FINGER rehabilitation robot

This paper describes the design and initial prototype of a thumb curling exoskeleton for movement therapy. This add-on device for the Finger INdividuating Grasp Exercise Robot (FINGER) guides the thumb through a single-degree-of-freedom naturalistic grasping motion. This motion complements the grasping motions of the index and middle fingers provided by FINGER. The kinematic design and mechanism synthesis described herein utilized 3D motion capture and included the determination of the principle plane of the thumb motion for the simple grasping movement. The results of the design process and the creation of a first prototype indicate that this thumb module for finger allows naturalistic thumb motion that expands the capabilities of the FINGER device.

Improving the match between ability and challenge: toward a framework for automatic level adaptation in game-based assessment and training

It is believed that the quality of arm mobility in planar reach movements can be adequately characterized by measures of planar position and vertical force. For the purpose of impairment assessment, it is further proposed that a complete picture of mobility performance can be represented through the assessment of metrics representative of each of four capacities: 1) Range of motion, 2) Range of force, 3) Control of motion, and 4) Control of force. In this paper, a set of games for mobility assessment is presented and initial plots of motion profiles and several computed metrics are shown for one patient in the performance of range of motion and control of motion assessments. Assessment plots are shown for four of seven training sessions and metrics are computed at each of the seven sessions to show the progression over the course of the 2-week clinical pilot study with the ArmAssist.

Development of a powered mobile module for the ArmAssist home-based telerehabilitation platform

The ArmAssist, developed by Tecnalia, is a system for at-home telerehabilitation of post-stroke arm impairments. It consists of a wireless mobile base module, a global position and orientation detection mat, a PC with display monitor, and a tele-rehabilitation software platform. This paper presents the recent development results on the mobile module augmenting its functionality by adding actuation components. Three DC servo motors were employed to drive the mobile module and a position control algorithm based on the kinematic model and velocity mode control was implemented such that the module tracks a path defined in the training software. Pilot tests of the powered mobile module were performed in experiments with different load conditions and two unimpaired subjects. Both test results show that the module is able to follow the predefined path within an acceptable error range for reach movement training. Further study and testing of the system in realistic conditions following stroke will be a future topic of research.

Cardiovascular function alterations induced by acute paradoxical sleep deprivation in rats

Sleep loss has been implicated in triggering the hypertension. The goal of the present study was investigated the possible mechanisms underlying cardiovascular alterations after acute paradoxical sleep deprivation (PSD). Male Wistar rats were assigned in two experimental groups: (1) control and (2) PSD for 24 h using the modified single platform method. Paradoxical sleep deprived rats exhibited higher blood pressure, heart rate (HR) and impaired baroreceptor sensitivity. After pharmacological autonomic double blockade (propranolol and methylatropine administration), intrinsic heart rate was decreased after PSD. The PSD rats showed a reduction in the vagal tone without affecting sympathetic tone. Isoproterenol administration (0.001, 0.01 and 1 µg/kg) induced an increase in ΔHR responses in PSD group. Electrocardiographic analysis in response to β-adrenergic stimulation indicated that PSD contributed to ventricular cardiac arrhythmias. Our findings suggest that acute paradoxical sleep loss induce cardiovascular alterations, autonomic imbalance accompanied by impaired baroreflex sensitivity and increased arrhythmia susceptibility.

Development of computer games for assessment and training in post-stroke arm telerehabilitation

Stroke is the leading cause of long term disability among adults in industrialized nations. The majority of these disabilities include deficiencies in arm function, which can make independent living very difficult. Research shows that better results in rehabilitation are obtained when patients receive more intensive therapy. However this intensive therapy is currently too expensive to be provided by the public health system, and at home few patients perform the repetitive exercises recommended by their therapists. Computer games can provide an affordable, enjoyable, and effective way to intensify treatment, while keeping the patient as well as their therapists informed about their progress. This paper presents the study, design, implementation and user-testing of a set of computer games for at-home assessment and training of upper-limb motor impairment after stroke.

Telerehabilitation: toward a cost-efficient platform for post-stroke neurorehabilitation

Motor deficits in the growing population of stroke survivors continue to strain global healthcare capacities. The use of telerehabilitation to address this need has been discussed for over a decade without a clear consensus on development strategy or a clear market success. In this paper, the cyclic and iterative phases of the Planning, Execution, Assessment (PLEXAS) rehabilitation cycle are discussed, and the potential roles of an integrated telerehabilitation platform within this cycle are presented. Some preliminary work on a multicenter project called TeleREHA is presented along with relevant clinical insight and discussion.

Effective Game use in Neurorehabilitation

Games possess highly favourable attributes to bring to the field of neurorehabilitation by means of providing motivation and goal-directed exercise tasks. For the use of games to be effectively integrated in the commercial and clinical rehabilitation marketplace, it is necessary that a unified and comprehensive rehabilitation gaming platform be developed following principles of user-centered design. The needed platform must contain compatible modules for the planning and execution of treatment as well as progress assessment, and its development must take into consideration the needs and viewpoints of the involved stakeholders and the required supporting factors, including: patient, prescriber, therapist, care-provider, family, clinic, as well as supporting scientific evidence, technology, and policy. A proposed platform and needed components are explained and an example prototype rehabilitation platform is provided for discussion.

Mating stimulates female feeding: testing the implications for the evolution of nuptial gifts

Nutritional benefits from nuptial gifts have been difficult to detect in some species, raising the question: what maintains nuptial feeding when gifts do not benefit females? The sensory trap hypothesis proposes that nuptial feeding may be explained by pre-existing sensory responses that predispose females to ingest gifts. Recent studies have shown that male seminal proteins can induce a nonspecific increase in female feeding after mating, which may represent a sensory trap for nuptial feeding if it results in increased intake of post-mating gifts. I tested these ideas using female beetles that ingest a spermatophore after mating. I show that males stimulate strongly increased female feeding post-mating. However, there was little evidence for dose dependence in the feeding response that could allow males to stimulate feeding beyond the female optimum. Moreover, the post-mating feeding response could not explain nuptial feeding: despite feeding more in general, newly mated females were less likely than nonmated females to ingest spermatophore gifts.

A variable structure pantograph mechanism for comprehensive upper extremity haptic movement training

Numerous haptic devices have been developed for neurorehabilitation of upper extremities, but their wide-spread use has been largely impeded for reasons of complexity and cost. In this paper we describe a variable structure pantograph mechanism that produces a versatile rehabilitation robot for movement training of the shoulder, elbow, and wrist. The device has three operational modes: ARM, REACH and WRIST. The performance of the mechanism, driven by series elastic actuators, is similar in all three operational modes while using a single control scheme and set of gains. This means a single device with minimal setup changes can be used to treat a variety of upper limb impairments following stroke, traumatic brain injury, or other direct trauma to the arm.

Real-time myoprocessors for a neural controlled powered exoskeleton arm

Exoskeleton robots are promising assistive/rehabilitative devices that can help people with force deficits or allow the recovery of patients who have suffered from pathologies such as stroke. The key component that allows the user to control the exoskeleton is the human machine interface (HMI). Setting the HMI at the neuro-muscular level may lead to seamless integration and intuitive control of the exoskeleton arm as a natural extension of the human body. At the core of the exoskeleton HMI there is a model of the human muscle, the "myoprocessor," running in real-time and in parallel to the physiological muscle, that predicts joint torques as a function of the joint kinematics and neural activation levels. This paper presents the development of myoprocessors for the upper limb based on the Hill phenomenological muscle model. Genetic algorithms are used to optimize the internal parameters of the myoprocessors utilizing an experimental database that provides inputs to the model and allows for performance assessment. The results indicate high correlation between joint moment predictions of the model and the measured data. Consequently, the myoprocessor seems an adequate model, sufficiently robust for further integration into the exoskeleton control system.

Association of paradoxical sleep deprivation and ecstasy (MDMA) enhances genital reflexes in male rats

Ecstasy ((+/-)3,4-methylenedioxymethamphetamine, MDMA) is a psychostimulant and a synthetic derivative of amphetamine that, according to its consumers, promotes the enhancement of sexual pleasure. This study sought to investigate the effects of ecstasy in the genital reflexes of paradoxical sleep deprived (PSD) male rats. Distinct groups of PSD rats were administered with saline or different doses of ecstasy. The incidence of genital reflexes was verified for 100 min. The four doses that were used induced genital reflexes in PSD animals and these significantly differed from their respective treated control groups. Under the influence of two intermediary doses (2.5 and 5mg/kg), all animals displayed erection and ejaculation. The frequency of genital reflexes was also significantly greater than in relation to the PSD-saline group. The comparison between cocaine and ecstasy in PSD rats revealed that ecstasy induced more erections and ejaculations than cocaine. Thus, the present results showed a great enhancement of the genital reflexes of PSD rats that might have occurred due to serotoninergic alterations induced by this illicit substance when associated to sleep deprivation.

Games among cannibals: competition to cannibalize and parent-offspring conflict lead to increased sibling cannibalism

Sibling cannibalism occurs in many species, yet understanding of sibling cannibalism as an adaptation currently lags behind understanding of other antagonistic interactions among siblings. Observed sibling cannibalism phenotypes likely reflect the interaction between competitive games among siblings and parent-offspring conflict. Using a game-theoretic approach, we derive optimal offspring cannibalism behaviour and parental modifiers that limit or facilitate cannibalism. The results are compared to contemporary frequency-independent analysis. With the addition of game interactions among siblings or parent-offspring co-evolution, our model predicts increased cannibalism (compared to the frequency-independent prediction), as offspring compete to eat siblings. When infertile eggs are present--strengthening competition--offspring risk eating viable siblings in order to gain access to infertile eggs, intensifying parent-offspring conflict. We use the results to make new predictions about the occurrence of sibling cannibalism. Additionally, we demonstrate the utility of trophic egg laying as a maternal mechanism to promote egg eating.

Monosialoganglioside (GM1) attenuates the behavioural effects of long-term haloperidol administration in supersensitive rats

In the present study we investigated the effects of co-administration of GM(1) (15.0 mg/kg, twice daily, for 30 days) and haloperidol (1.0 mg/kg, twice daily, for 30 days), as well as the effects of a 5-day treatment with this dose of GM(1) after withdrawal from haloperidol in rats. The animals were evaluated in the open-field test and apomorphine-induced stereotyped behaviour. The results show that GM(1) was able to attenuate dopaminergic supersensitivity evaluated by the locomotion frequency at 24 and 48 h after the withdrawal from haloperidol. On the other hand, rearing frequency was changed neither by haloperidol nor by GM(1.) In haloperidol-treated rats immobility time differs from 30 min observation session in comparison with the following sessions after the withdrawal from neuroleptic. Apomorphine-induced stereotyped behaviour produced a significant increase in scores of haloperidol-withdrawn rats. GM(1) did not modify the haloperidol effects and did not change the dopamine receptor affinity to apomorphine 100 h from abrupt neuroleptic withdrawal.

A pilot study of defenses in adults with personality disorders entering psychotherapy

This study examined defensive functioning in adults entering open-ended dynamic psychotherapy and determined whether defenses predict retention at 1 year. Beginning at about the fifth session, 14 adults with personality and or depressive disorders entering open-ended dynamic psychotherapy had five therapy sessions audiotaped. The sessions were rated according to the Defense Mechanism Rating Scales, quantitative method. Interrater reliability of overall defensive functioning (ODF) and the number of defenses used per session were intraclass R = .85 and .83, respectively, whereas that of seven defense levels yielded a median of .625 (range .52 to .80). Stability of ODF across the five sessions was intraclass R = .48. The 11 subjects with personality disorders (PDs) used predominantly lower immature (49.3%) and neurotic (40.8%) level defenses. Subjects with borderline PD had significantly lower ODF than those with other PD types. Higher ODF was associated with remaining in treatment at 1 year, although this was confounded with a higher frequency of weekly sessions. Quantitative assessment of defenses demonstrated fair to excellent reliability and indicated that in the short term approximately half of defensive functioning reflects a stable repertoire, whereas the remaining variation may be due to occasion and error. PDs and especially BPD are characterized by a predominance of lower defenses. Higher defensive functioning was associated with twice-weekly sessions and retention in therapy at 1 year. In therapy, adjusting technique to the patient's defenses may improve retention and outcome.

Is Arrhythmia Detection by Automatic External Defibrillator Accurate for Children?

Background —Use of automatic external defibrillators (AEDs) in children aged <8 years is not recommended. The purpose of this study was to develop an ECG database of shockable and nonshockable rhythms from a broad age range of pediatric patients and to test the accuracy of the Agilent Heartstream FR2 Patient Analysis System for sensitivity and specificity.

Methods and Results —Children aged ≤12 years who either developed arrhythmias or were at risk for developing arrhythmias were studied. Two sources were used for the database: children whose rhythms were recorded prospectively via a modified AED and children who had arrhythmias captured on paper and digitized for subsequent analysis. The rhythms were divided into 5-second strips, classified by 3 reviewers, and then assessed by the AED analysis algorithm. A total of 696 five-second rhythm strips from 191 children (81 female and 110 male) aged 1 day to 12 years (median 3.0 years) were analyzed. There was 100% specificity for nonshockable rhythms. Sensitivity for ventricular fibrillation was 96%.

Conclusions —There was excellent AED rhythm analysis sensitivity and specificity in all age groups for ventricular fibrillation and nonshockable rhythms. The high specificity and sensitivity indicate that there is a very low risk of an inappropriate shock and that the AED correctly identifies shockable rhythms, making the algorithm both safe and effective for children.

Contribution of patient defense mechanisms and therapist interventions to the development of early therapeutic alliance in a brief psychodynamic investigation

This preliminary study examined how patients' defense mechanisms and psychotherapists' techniques influence early alliance formation. The authors assessed the relationships among defense mechanisms, therapist interventions, and the development of alliance in a sample of 12 patients undergoing Brief Psychodynamic Investigation (4 sessions). Alliance development occurred rapidly and was clearly established by the third session. Neither defensive functioning nor supportive or exploratory interventions alone differentiated early alliance development. However, the degree of adjustment of therapists' interventions to patients' level of defensive functioning discriminated a low alliance from both improving and high alliances. The adjustment of therapeutic interventions to patients' level of defensive functioning is a promising predictor of alliance development and should be examined further, alongside other predictors of outcome.

Pediatric digital echocardiography: a study of the analog-to-digital transition

Limited information is available that describes the practical conversion of a pediatric echocardiography laboratory from videotape to a primarily digital format. To help pediatric echocardiographers begin to make the analog-to-digital transition, we report our pediatric digital acquisition protocol and the acquisition and storage parameters of 1000 unselected, consecutive digitally acquired studies of pediatric patients with known or suspected congenital or acquired heart disease. With the use of our acquisition protocol, a complete normal study requires 46 moving clips and 12 still-frame images. Five hundred consecutive patient studies acquired with "high" JPEG (Joint Photographers Experts Group) compression (group 1) were compared with the next 500 examinations acquired using "medium" JPEG compression (group 2) for number of moving clips, still images, and megabytes of storage space. No intergroup difference was found in the number of moving clips or still images. When JPEG compression was decreased from high to medium, the average clip storage requirement per patient increased, and the number of patients stored per 230-MB magneto optical disk decreased significantly. Non-ECG-triggered timed single-plane clips and still images required significantly more storage space than ECG-triggered single-beat clips and still images. The frequency of multiplane sweeps was.03% and was independent of diagnosis. With the use of high JPEG compression, the digital storage cost per patient was $1.90, which was 6.0 times greater than that for simultaneously recorded 120-minute VHS videotape. Many features of the digital paradigm, including decreased MOD storage space, enhanced serial study comparisons, random image access, and improved image quality, mitigate this cost differential.

Applications of pacing strategies in neonates and infants

Pacing in neonates and infants continues to be challenging due to size constraints, growth potential, and the need for life long pacing. Indications for permanent pacing in pediatric patients have been difficult to determine due to the lack of data from controlled studies and multicenter trials. Temporary pacing has been useful to restore cardiac output in pediatric patients quickly and efficiently. Methods of temporary pacing include transcutaneous, transesophageal, transvenous, and epicardial. Permanent pacemaker implantation can be accomplished by transvenous or epicardial approaches, but the use of transvenous pacing in neonates and infants offers no advantages over epicardial pacing. Transvenous pacing in infants is often prohibitive due to size and growth constraints as well as the subsequent risk of skin erosion and venous thrombosis. Smaller pulse generators, multiprogrammable features, and steroid-eluting epicardial leads are a few of the technological advances that have made pacing in neonates and infants easier and safer. Data supporting the use of pacing systems in very young patients are sparse. Pacing 'indications' should be viewed as guidelines until such data can be accumulated.

Effectiveness of psychotherapy for personality disorders

OBJECTIVE

The authors examined the evidence for the effectiveness of psychotherapy for personality disorders in psychotherapy outcome studies.

METHOD

Fifteen studies were located that reported data on pretreatment-to-posttreatment effects and/or recovery at follow-up, including three randomized, controlled treatment trials, three randomized comparisons of active treatments, and nine uncontrolled observational studies. They included psychodynamic/interpersonal, cognitive behavior, mixed, and supportive therapies.

RESULTS

All studies reported improvement in personality disorders with psychotherapy. The mean pre-post effect sizes within treatments were large: 1.11 for self-report measures and 1.29 for observational measures. Among the three randomized, controlled treatment trials, active psychotherapy was more effective than no treatment according to self-report measures. In four studies, a mean of 52% of patients remaining in therapy recovered--defined as no longer meeting the full criteria for personality disorder--after a mean of 1.3 years of treatment. A heuristic model based on these findings estimated that 25.8% of personality disorder patients recovered per year of therapy, a rate sevenfold larger than that in a published model of the natural history of borderline personality disorder (3.7% recovered per year, with recovery of 50% of patients requiring 10.5 years of naturalistic follow-up).

CONCLUSIONS

Psychotherapy is an effective treatment for personality disorders and may be associated with up to a sevenfold faster rate of recovery in comparison with the natural history of disorders. Future studies should examine specific therapies for specific personality disorders, using more uniform assessment of core pathology and outcome.

Permanent cardiac pacemakers: issues relevant to the emergency physician, part II

Many people benefit from the implantation of cardiac pacemakers for management of certain cardiac dysrhythmias. These patients are seen regularly in the Emergency Department with a variety of pacemaker complications and malfunctions. The presence of a pacemaker may also affect management of unrelated medical problems. This, the second of a two-part series, covers the causes, diagnosis, and management of pacemaker malfunction; the pacemaker syndrome; the pacemaker Twiddler's syndrome; and other considerations in the paced patient including diagnosis of acute myocardial infarction, ACLS protocols, trauma, and sources of interference.

Permanent cardiac pacemakers: issues relevant to the emergency physician, Part I

Many people benefit from the implantation of cardiac pacemakers for management of certain cardiac dysrhythmias. These patients are seen regularly in the emergency department with a variety of pacemaker complications and malfunctions. The presence of a pacemaker may also affect management of unrelated medical problems. This two-part series reviews the medical issues related to patients with permanent pacemakers. Part I covers pacing modes and terminology, complications of the implant procedure, and the approach to a patient with a permanent pacemaker. Part II covers the causes, diagnosis and management of pacemaker malfunction; the pacemaker syndrome; the pacemaker Twiddler's syndrome; and other considerations in the paced patient including diagnosis of acute myocardial infarction, ACLS protocols, trauma, and sources of interference. Indications for permanent pacemaker implantation and temporary external pacing will not be covered.

Sequential consequences of therapists' interventions

Using sequential analysis, the authors examined how therapists' actions related to the verbal disclosure and defensive patterns that followed therapists' interventions within a single therapy hour for 20 patients. At the same time, a new measure, the Psychodynamic Intervention Rating Scale (PIRS), was tested for reliability and construct validity. Results indicated that therapists fit their styles of intervention to patients' levels of distress and functioning. Within the session, patient's emotional elaboration was followed by therapist's defense interpretation, followed by more patient emotional elaboration. Patient elaboration of significance was followed by more transference interpretation, followed by more patient elaboration of significance. Noninterpretive interventions were followed by patient's disclosure of facts, not emotion. Both interpretive intervention process sequences and therapist's use of support predicted posttreatment symptom reduction. The PIRS was shown to have satisfactory reliability and construct validity.

Convergent and discriminant validity of overall defensive functioning

We examined the validity of the construct of overall defensive functioning and its discrimination from standard diagnostic assessments. Within a multisite field trial, patients received intake diagnostic interviews by clinicians who made standard axis I through V diagnoses, then rated defense mechanisms using the Defense Mechanism Rating Scales (DMRS). Patients filled out self-report measures of distress and defenses, the SCL-90-R, and Defense Style Questionnaire (DSQ). Overall defensive functioning (ODF) scales were derived from both the DMRS and the DSQ. Overlap between clinical and self-report ratings of defenses was modest. By two different methods of factor analysis, followed by confirmatory factor analysis, clinical ratings of ODF were clearly discriminable from axis I, axis II personality disorders, current and usual global functioning, and subjective distress. ODF measured by the DSQ was not clearly discriminated from subjective distress ratings, consistent with the hypothesis that subjective distress may distort conscious derivatives of actual defensive processes. The DSQ alone probably should not be considered as a substitute for observer-rated assessment of defensive functioning, although further study of the issue is warranted.

A naturalistic study of the chronic fatigue syndrome among women in primary care

Chronic fatigue syndrome (CFS), a controversial illness without clear etiology, causes profound debilitation in its sufferers. This study explored subjects' perceptions of the variables that mediated the course of their illness and identified coping strategies in 15 women with CFS referred from the practice of a primary care physician. Exploratory semistructured interviews were adapted from Kleinman's Illness Narratives. Four instruments were used: the Beck Depression Inventory, the Sickness Impact Profile, a modified Karnofsky scale, and the Defense Mechanism Rating Scale. Of the 15 women, 60% reported improvement and/or recovery at the time of the interview. Improvement was associated with social support and lower levels of depressive symptoms. Health status was influenced by how subjects perceived their illness, their future, and the doctor's prognosis; and by the physician's early diagnosis, validation of the CFS, and intensive medical follow-up. Obsessional and healthy neurotic defense levels predominated, which differs from historical comparison groups with dysthymia and panic disorder. Psychological adaptation to CFS is similar to adaptive coping in other chronic illnesses: subjective perceptions of health status can predict functional status. Physician validation is particularly important given the controversial status of CFS. Maintaining relationships with others--doctor, work, family, and group/spiritual activities reflected healthy coping strategies that promoted hope and attitudinal shifts. The finding of a mixture of neurotic and healthy defenses and a low proportion of defenses associated with personality disorders has not been previously reported in the CFS literature and warrants further investigation.

Field trial of a diagnostic axis for defense mechanisms for DSM-IV

Following critiques that the DSM multiaxial system lacks psychodynamic information useful for treatment, an axis for defense mechanisms was developed for DSM-IV, including up to 7 individual defenses from a glossary of 27, and 3 predominant defense levels from a list of 7. We tested the feasibility, reliability, and discriminability of the proposed axis. Clinician and psychiatric resident volunteers were trained at two U.S. and one Norwegian sites. After conducting initial interviews on 107 patients, they rated the DSM-III-R and defense axes, as did a second blind rater. Median kappa reliabilities were .42 (individual defenses), and .47 (defense levels). A summary measure, Overall Defensive Functioning (ODF), had similar reliability to current GAF (IR .68 vs. .62), similar 1-month stability (.75 vs. .78), but greater 6-month stability (.51 vs. .17). Independent of Axis III, ODF had small to moderate associations with other Axes and symptoms. Our findings indicate that the defense axis is a feasible, acceptably reliable, and nonredundant addition to DSM-IV, which may prove useful for planning and conducting treatment.

New mutations in the KVLQT1 potassium channel that cause long-QT syndrome

BACKGROUND

Long-QT syndrome (LQTS) is an inherited cardiac arrhythmia that causes sudden death in young, otherwise healthy people. Four genes for LQTS have been mapped to chromosome 11p15.5 (LQT1), 7q35-36 (LQT2), 3p21-24 (LQT3), and 4q25-27 (LQT4). Genes responsible for LQT1, LQT2, and LQT3 have been identified as cardiac potassium channel genes (KVLQT1, HERG) and the cardiac sodium channel gene (SCN5A).

METHODS AND RESULTS

After studying 115 families with LQTS, we used single-strand conformation polymorphism (SSCP) and DNA sequence analysis to identify mutations in the cardiac potassium channel gene, KVLQT1. Affected members of seven LQTS families were found to have new, previously unidentified mutations, including two identical missense mutations, four identical splicing mutations, and one 3-bp deletion. An identical splicing mutation was identified in affected members of four unrelated families (one Italian, one Irish, and two American), leading to an alternatively spliced form of KVLQT1. The 3-bp deletion arose de novo and occurs at an exon-intron boundary. This results in a single base deletion in the KVLQT1 cDNA sequence and alters splicing, leading to the truncation of KVLQT1 protein.

CONCLUSIONS

We have identified LQTS-causing mutations of KVLQT1 in seven families. Five KVLQT1 mutations cause the truncation of KVLQT1 protein. These data further confirm that KVLQT1 mutations cause LQTS. The location and character of these mutations expand the types of mutation, confirm a mutational hot spot, and suggest that they act through a loss-of-function mechanism or a dominant-negative mechanism.

Defensive functioning predicts improvement in major depressive episodes

We investigated the predictive effect of psychological defenses on the course of major depression in a subsample of psychiatric patients from a larger study. We tested the hypothesis that a group of eight defenses, associated with depression in previous research, would predict, outcome of major depression. After an intake interview, 37 patients were rated on all DSM-III-R Axes, the SCL-90-R, and 28 defenses, using the Defense Mechanism Rating Scales. At 6-month follow-up interview, SCL-90-R and Global Assessment and Functioning (GAF) were redetermined on 34 (92%), 16 of whom had major depression at intake. Overall Defensive Functioning (ODF) significantly predicted GAF at 6-month follow-up over and above initial level of global functioning and presence of a personality disorder. The group of eight defenses were identified more often (p = .068) in depressed patients who improved less than predicted by their initial functional status. The high adaptive level defense, self-observation, was identified more often in those who improved more than predicted by their initial status. Our findings support the theory of a hierarchy of defenses, and the mediating effects of specific low and high adaptive level defenses on the course of a major depressive episode. Further research should examine passive aggression, acting out, help-rejecting complaining, splitting of self-images, splitting of others' images, projective identification, projection, and devaluation in relationship to the onset, course, and treatment response of depressive disorders.

Ventricular tachycardia in neonates

Infant VT can be a devastating arrhythmia, with high mortality for those presenting with myocarditis, long QT syndrome, or cardiovascular collapse with rapid VT due to tumors. While management of these patients can be challenging and discouraging, other infants with wide QRS rhythms tend to follow a more benign course. These latter patients have accelerated idiopathic ventricular rhythm or aberrant forms of infant supraventricular tachycardia. Distinguishing these forms of wide QRS tachycardia from the more lethal forms is paramount to institution of appropriate therapies.

The psychosocial treatments interview for anxiety disorders. A method for assessing psychotherapeutic procedures in anxiety disorders

The authors report on development, reliability, and findings of the Psychosocial Treatments Interview (PTI) to assess treatments reported by patients in a naturalistic study of the longitudinal course of anxiety disorders. The PTI ascertains frequency of different types of psychosocial treatments, based on patients' reports. The PTI showed good internal consistency and very good interrater reliability. At first 6-month follow-up, the most common modalities were supportive, medication discussion, and dynamic intervention. Combinations were common. Delivery of treatments differed by site. Overall, the PTI fills a methodological need for the assessment of the treatments reported by patients in naturalistic follow-up studies.