Agenesis of the corpus callosum in a mother and son

Most reported familial cases of agenesis of the corpus callosum have followed either an autosomal recessive or an X-linked recessive pattern of inheritance. To the best of our knowledge, there is only one previous report of a family showing clear-cut autosomal dominant inheritance. We present the second such family, among whom a mother and her son had moderately severe coordination problems and low-normal intelligence. We suggest that agenesis of the corpus callosum, when transmitted as an autosomal dominant trait, is clinically characterized by a relatively milder phenotype than that occurring when inheritance is either autosomal or X-linked recessive and may be more common than has been thought.     

Where differences persist: Robotic vs. human movement control

Summary form only given. A partial list of features on which human movement control systems (HMCSs) and robotic movement control systems (RMCSs) differ is presented. It is concluded that along with the obvious stimulation that is generated back and forth between the study of the HMCS and that of RMCS, it is tempting to point only to the similarities between the two systems. However, it should be remembered that differences do exist between these systems and forced attempts to prove similarities may be very misleading     

Task Switching After Cerebellar Damage.

The authors of this study investigated task switching following cerebellar damage. The study group consisted of 7 children and adolescents (M age = 13.8 years) who underwent surgical removal of a benign posterior fossa tumor. They were tested at a sufficient interval after surgery (M lag = 6.13 years) for restoration of normal cognitive skills and intelligence. Although all showed normal learning of the task compared with control participants, when rapid behavioral changes were required (short preparation time), they exhibited behavioral rigidity manifested by enhanced switching cost. These results are in line with another study on serial reaction time with the same patients (A. Berger et al., in press). They have important implications for our understanding of the cognitive sequelae of early cerebellar damage as well as the involvement of the cerebellum in task switching. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classification of finger activation for use in a robotic prosthesis arm

Hand amputees would highly benefit from a robotic prosthesis, which would allow the movement of a number of fingers. In this paper we propose using the electromyographic signals recorded by two pairs of electrodes placed over the arm for operating such prosthesis. Multiple features from these signals are extracted whence the most relevant features are selected by a genetic algorithm as inputs for a simple classifier. This method results in a probability of error of less than 2%.     

Overcoming selective ensemble averaging: unsupervised identification of event-related brain potentials

We present a novel approach to the problem of event-related potential (ERP) identification, based on a competitive artificial neural network (ANN) structure. Our method uses ensembled electroencephalogram (EEG) data just as used in conventional averaging, however without the need for a priori data subgrouping into distinct categories (e.g., stimulus- or event-related), and thus avoids conventional assumptions on response invariability. The competitive ANN, often described as a winner takes all neural structure, is based on dynamic competition among the net neurons where learning takes place only with the winning neuron. Using a simple single-layered structure, the proposed scheme results in convergence of the actual neural weights to the embedded ERP patterns. The method is applied to real event-related potential data recorded during a common odd-ball type paradigm. For the first time, within-session variable signal patterns are automatically identified, dismissing the strong and limiting requirement of a priori stimulus-related selective grouping of the recorded data. The results present new possibilities in ERP research.     

Pygmalion, Galatea, and the Golem: Investigations of biased and unbiased teachers.

Examined differential expectancy effects as a function of teachers' susceptibility to biasing information and the distinction between positive ("Galatea") and negative ("Golem") outcomes of teacher expectancies. 26 biased and unbiased student teachers were identified on the basis of their susceptibility to biasing information in scoring drawings allegedly made by high- or low-status students. High-bias teachers treated the students they perceived to be of low potential negatively while at the same time treating randomly selected students in a manipulated high-expectancy group as favorably as they treated the students they themselves nominated as being of high potential. Unbiased teachers treated all 3 groups of students (N?=?202) equitably. The strongest and most consistent Golem effects were observed for behavioral manifestations of dogmatism. These patterns of differential negative expectancy effects were evident not only in teachers' behavior but also in students' actual performance of specially designed tasks. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

FNS Control Schemes for the Upper Limb

This paper is concerned with the problems of control associated with the application of functional neuromuscular stimulation of the upper limb, concentrating on elbow flexion/extension and wrist pronation/supination. A closed-loop controller is needed in order to overcome the gain nonlinearities and plant dynamic parameter variations. Controllers were developed based on models and parameters previously established. Two controllers are discussed in detail, a thirdorder feedforward controller and a model reference adaptive controller. There were no striking differences in the performances of the thirdorder controllers. The conventional controllers, however, required a lengthy a priori identification procedure each time they were used. This was performed implicitly by the adaptive controller within a few seconds, making it a practical proposition for an FNS controller.     

Modeling and estimation of single evoked brain potential components

Presents a novel approach to solving the single-trial evoked-potential estimation problem. Recognizing that different components of an evoked potential complex may originate from different functional brain sites and can be distinguished according to their respective latencies and amplitudes, the authors propose an estimation approach based on identification of evoked potential components on a single-trial basis. The estimation process is performed in 2 stages: first, an average evoked potential is calculated and decomposed into a set of components, with each component serving as a subtemplate for the next stage; then, the single measurement is parametrically modeled by a superposition of an emulated ongoing electroencephalographic activity and a linear combination of latency and amplitude-corrected component templates. Once optimized, the model provides the 2 assumed signal contributions, namely the ongoing brain activity and the single evoked brain response. The estimator's performance is analyzed analytically and via simulation, verifying its capability to extract single components at low signal-to-noise ratios typical of evoked potential data. Finally, 2 applications are presented, demonstrating the improved analysis capabilities gained by using the proposed approach. The first application deals with movement related brain potentials, where a change of the single evoked response due to external loading is detected. The second application involves cognitive event-related brain potentials, where a dynamic change of 2 overlapping components throughout the experimental session is detected and tracked     

Development of a closed-loop pacemaker controller regulating mixedvenous oxygen saturation level

A simplified model of the CV system is developed where the heart rate (HR) is the controlled input variable, the mixed venous oxygen saturation level (SO₂) is the model output, and the work loads are the disturbances. The model relates the SO₂ level to the HR and the work through linear relationships, gains, and first-order time constants, and nonlinear relationships, the most important being the nonlinear relation between cardiac output (CO) and heart rate due to the optimal-heart-rate phenomenon. The critical gain is calculated and is shown to be a function of the CO due to the shortening of circulation time delay with increased CO-a stabilizing phenomenon. The step response of the system in open and closed-loop modes to various loads are simulated in the time domain. A proportional-plus-derivative controller which in the simulation increases SO₂ from 36% with a 100-W load at constant HR to 57% is described. This is achieved at a cost of increasing HR to 62 to 96 beats/min     

Feeding Responses of Free-flying Honeybees to Secondary Compounds Mimicking Floral Nectars

The role of secondary compounds (SC) in deterring herbivores and pathogens from vegetative parts of plants is well established, whereas their role in plant reproductive organs such as floral nectar is unclear. The present study aimed to reveal the response of free-flying honeybees to naturally occurring concentrations of four SC in floral nectar. We selected nicotine, anabasine, caffeine, and amygdalin, all of which are found in nectar of various plants. In repeated paired-choice experiments, we offered 20% sucrose solution as control along with test solutions of 20% sucrose with various concentrations of the above SC. Except for anabasine, naturally occurring concentrations of SC did not have a deterring effect. Furthermore, low concentrations of nicotine and caffeine elicited a significant feeding preference. SC can, therefore, be regarded as postingestive stimulants to pollinators, indicating that the psychoactive alkaloids in nectar may be a part of their mutualistic reward. Further studies are needed to test our hypothesis that psychoactive alkaloids in nectar impose dependence or addiction effects on pollinators.