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At least 667 records · Page 37Linked to original sources
PubMedDate not supplied

[The theory of functional systems and purposeful behavior].

The role of probability forecasting in the purposive behavior under conditions of subjective uncertainty is considered in terms of the theory of functional systems. Participation of the probability forecasting in the afferent synthesis, goal formation, formation of the acceptor of action result and action program, and, finally, in the action program actualization is substantiated. The model of behavior under conditions of subjective uncertainty is advanced. It includes all the classical elements of the model of behavioral act developed by P.K. Anokhin. In order to take into account the probability aspects of behavior, the role of probability forecasting is emphasized at every stage of the system functioning. In addition to the classical elements, two novel components are introduced. These are the "memory buffer" (results of searching reactions) and the apparatus of probability decisions about changes in the action program. By the memory buffer an apparatus is meant, which gathers and stores the information about the results of many behavioral acts performed during the actualization of the action program. This information is used in the process of making a probability decision as whether to alter or not the action program after each specific behavioral act. Such an approach integrates the probability forecasting and the theory of functional systems. The theory becomes universal, i.e., applicable not only to deterministic but also to probabilistic environments.

Animals↗
PubMed1993

Greater than the sum of its parts. II. Matter-energy processing subsystems.

Behavioral science theory has changed greatly since 1978, when Miller's Living Systems was published. Much of the change represents progress, particularly in the biological fields. During that time, living systems theory (LST) developed in many ways. Among the most significant developments have been the addition of another level, the community, to the seven levels previously included in LST and the addition of another subsystem, the timer, to become the 20th subsystem. The present article is the second to be published in this journal which describe relatively briefly and simply the current state of scientific knowledge about the subsystems of living systems. It deals with the first six matter-energy processing subsystems, the ingestor, distributor, convertor, producer, matter-energy storage, and extruder.

Adaptation, Physiological↗
PubMed2003

Regime changes in ecological systems: an information theory approach.

We present our efforts at developing an ecological system index using information theory. Specifically, we derive an expression for Fisher Information based on sampling of the system trajectory as it evolves in the space defined by the state variables of the system, i.e. its state space. The Fisher Information index, as we have derived it, is a measure of system order, and captures the characteristic variation in speed and acceleration along the system's periodic steady-state trajectories. When calculated repeatedly over the system period, this index tracks steady states and transient behavior. We believe that such an index could be useful in detecting system 'flips' associated with a regime change, i.e. determining when systems are in a transient between one steady state and another. We illustrate the concepts using model ecosystems.

Animals↗
PubMed2004

Dissociating explicit and procedural-learning based systems of perceptual category learning.

A fundamental question is whether people have available one category learning system, or many. Most multiple systems advocates postulate one explicit and one implicit system. Although there is much agreement about the nature of the explicit system, there is less agreement about the nature of the implicit system. In this article, we review a dual systems theory of category learning called competition between verbal and implicit systems (COVIS) developed by Ashby et al. The explicit system dominates the learning of verbalizable, rule-based category structures and is mediated by frontal brain areas such as the anterior cingulate, prefrontal cortex (PFC), and head of the caudate nucleus. The implicit system, which uses procedural learning, dominates the learning of non-verbalizable, information-integration category structures, and is mediated by the tail of the caudate nucleus and a dopamine-mediated reward signal. We review nine studies that test six a priori predictions from COVIS, each of which is supported by the data.

Caudate Nucleus↗
PubMed2003

Optimal stochastic correction strategies for rigid-body target motion.

PURPOSE: To derive optimal correction strategies for setup errors, including the uncertainty in their measurement, and to analyze their impact on treatment margins. METHODS AND MATERIALS: New concepts like image-guided radiotherapy aim to provide an increasing amount of targeting information during treatment. Future treatment devices incorporating imaging capabilities will facilitate frequent correction of treatment setup errors. It is, therefore, possible to design new correction protocols that reduce not only systematic but also random setup errors. A novel, very general approach to developing optimal correction strategies in the presence of measurement uncertainties is derived from linear systems theory. In the simplest approach, the state variable of the system, which represents the patient, is the spatial displacement of the center-of-mass of the clinical target volume with respect to the planning CT. This displacement is the sum of a systematic and a random component. Uncertainties in the measured value of the state variable due to the measurement process, image processing technique, or organ deformation are naturally incorporated into a linear system. The true value of the displacement can be estimated from the noisy measurements with a stochastic filter (Kalman filter). These estimates provide an optimal control law for the system and therefore optimal values for the setup corrections. In the case of unknown systematic and random error variances, an adaptive version of the filter was implemented. The statistical properties of the filter were investigated by performing simulations of the state space model and assessed for individual patients and a large patient population subject to different action criteria. RESULTS: Over a patient population, the corrections by the Kalman filter estimates are always advantageous compared with the corrections by the measured values themselves. For a small percentage of individual patients, however, the Kalman corrections worsen the results. For large measurement error, the residual standard deviation of the random setup errors can be reduced by approximately 28% for over 90% of the patients. The uncertainty in the measured value impairs the ability to completely account for uncertainties. CONCLUSIONS: The Kalman estimates provide an effective means to perform daily setup corrections in the presence of measurement errors. The linear system approach is very versatile and can be extended to more general state variables.

Algorithms↗
PubMed2001

The Feldenkrais Method: a dynamic approach to changing motor behavior.

This tutorial describes the Feldenkrais Method and points to parallels with a dynamic systems theory (DST) approach to motor behavior Feldenkrais is an educational system designed to use movement and perception to foster individualized improvement in function. Moshe Feldenkrais, its originator, believed his method enhanced people's ability to discover flexible and adaptable behavior and that behaviors are self-organized. Similarly, DST explains that a human-environment system is continually adapting to changing conditions and assembling behaviors accordingly. Despite little research, Feldenkrais is being used with people of widely ranging ages and abilities in varied settings. We propose that DSTprovides an integrated foundation for research on the Feldenkrais Method, suggest research questions, and encourage researchers to test the fundamental tenets of Feldenkrais.

Activities of Daily Living↗
PubMed2004

[Animal testing ethics and human testing. Thoughts on our conduct with and our relationship to animals].

After many years of experimental work with animals of diverse species, the author felt confronted with the question whether the great expenditure of sacrificed animal life would pay off when compared with the results gained. By self-critically considering his work, he gradually experienced a conversion from an unconcerned experimenter to a man feeling a deep sympathy with his fellow creatures. This motivated him to ponder the true nature of animals. Instead of applying ethics--though justified in its own realm--the author preferred to look at the problem using the General Systems Theory (GST), which can describe "the other side" of any system, the side into which any system may occasionally or necessarily transform. It occurred to him to assume that--provided we see a living organism as a system (as Ludwig von Bertalanffy, the founder of GST, did)--the "other side" of the animal would correspond to an innocent "genius" who suffers for man (thereby assuming a Christ-like position), whereas in its transitory life the true essence of the animal is hidden. Thus, by fancifully viewing the role of animals destined to suffer, a connection between GST and theology or religion arises. The consequence for us would be to pay honour to the test animal, irrespective of whether or not painful experiments could be avoided. The differentiation between a sacrifice (spiritually surrendering for a greater good) and a victim (involuntarily subjected to suffering) reveals that the experimental animal primarily belongs to the latter. But it can be elevated to the former when the full meaning of its suffering becomes obvious. The same holds true for "human testing", if, in contrast to the formidable atrocities, e.g. of concentration camps, the momentum of voluntariness is guaranteed, as pioneers of medical research frequently demonstrated by carrying out experiments on themselves.

Animal Experimentation↗
PubMedDate not supplied

[Biology of cardiac and vascular senescence].

None of the many theories of senescence can account for the aging process in its entirety. These theories include the evolutionary theory of aging and its EvoDevo corollary, the replicative senescence and free radicals theory, theories based on large-scale analyses (proteomics, etc.), and systemic theories. Cardiovascular senescence is first and foremost due to vascular senescence. Aging is associated with enhanced aortic characteristic impedance, which is mainly due to glycation of vessel wall proteins. This increased impedance overloads the left ventricle and causes compensatory left ventricular hypertrophy, usually associated with fibrosis. Extreme aging (> 80 years in humans, > 30 months in rats) is associated with age-related heart failure. Senescence favors heart failure, atrial fibrillation and cardiac hypertrophy. It is also associated with increased systolic pressure and decreased diastolic pressure. The most characteristic features are enhanced pulse pressure and arterial compliance.

Age Factors↗
PubMedDate not supplied

[The induction of psychopathology by somatic disorders, medications, toxins and drugs after systemic disorders].

The purpose of this article is to review the somatic disorders, drugs and toxics more often related to psychopathology. It is also exposed the conceptual framework chosen for this task, based in the nonlinear dynamical systems theory and in a recently proposed subdivision of central nervous system. We intuitively suggest that most psychopathological syndromes could be correlated with the cerebral dysfunction conditioned by the self-organization of dissipative structures formed by hierarchical and diffuse subsystems interrelated neurons groups. Any perturbation which affect these subsystems in a brain region, and change enough their activation level and interaction pattern to make any of these interactions functionally insufficient, could begin the process.

Brain↗
PubMedDate not supplied

[Evaluation of the role of the adaptive result in the theory of the functional systems].

The fundamental of the theory of the functional systems, i.e., the concept of the useful adaptive result as a universal system-forming factor is considered. It is suggested that the adaptive result is not system-forming in behaviors actualized exclusively due to activity of systems developed earlier. It is argued that positive mutations may serve as the system-forming factor for hereditary determined behavioral forms. In all other cases of goal-directed behavior (except conditioning) the aim of performance as a model of the future result plays the decisive role. Only in conditioning the classical concept of the system-forming role of the adaptive result seems to be undeniable. The refined ideas about the mechanisms of formation of the functional systems may be useful in analysis of a number of animal and human functions (learning, emotional stress, neuroses, etc.).

Animals↗
PubMed1996

Nonlinear dynamics and quantitative EEG analysis.

Quantitative, computerized electroencephalogram (EEG) analysis appears to be based on a phenomenological approach to EEG interpretation, and is primarily rooted in linear systems theory. A fundamentally different approach to computerized EEG analysis, however, is making its way into the laboratories. The basic idea, inspired by recent advances in the area of nonlinear dynamics and chaos theory, is to view an EEG as the output of a deterministic system of relatively simple complexity, but containing nonlinearities. This suggests that studying the geometrical dynamics of EEGs, and the development of neurophysiologically realistic models of EEG generation may produce more successful automated EEG analysis techniques than the classical, stochastic methods. A review of the fundamentals of chaos theory is provided. Evidence supporting the nonlinear dynamics paradigm to EEG interpretation is presented, and the kind of new information that can be extracted from the EEG is discussed. A case is made that a nonlinear dynamic systems viewpoint to EEG generation will profoundly affect the way EEG interpretation is currently done.

Brain↗
PubMed1988

[Hallucinatory structure].

Systemic methodology is restored to so that a demonstration is made which shows hallucination not being an independent element. Quite contrary, it is the author's contention that this is a structure-formed interacting group element coupled in function of an arrangement the basis pathology thus determined. I.E., hallucination is an open system at a set point with pathology. Hence--within certain limits, of course--the equilibrium establishes an arrangement whose characteristics enable any observer to identify hallucination as such. Since the methodology is in accordance with the General System Theory, the elements involved are studied like functional parts within a system. In other words, neither determinism nor simple causation are resorted to. Since--according to the GST--there is a higher relevance among connected elements which is not to be found among independent ones, thus a functional description is of a higher relevance than a particular one. So, the structure is proposed as a functional arrangement.

Hallucinations↗
PubMedDate not supplied

Theory, quality, and economy: a winning combination.

To meet quality and cost outcomes, a psychiatric hospital used a combination of strategies based on leadership and system theories. Leadership approaches included credibility, vision, positive self-regard, and communication. Systems initiatives included using reinforcing and balancing feedback loops and shifting the burden structures. This integration of theory, quality, and economy proved to be a winning combination.

Chicago↗
PubMed2000

A dynamical systems approach to manual tracking performance.

Manual tracking performance was investigated from the perspective of dynamical systems theory. The authors manipulated the type of visual display, the control system dynamics, and the frequency of the sinusoidal input signal to examine couplings with various phases between the visual signal and control movements. Analyses of the system output amplitude ratio and relative phase showed that participants (N = 24) performed poorly with 90 degrees relative phase coupling. All the couplings became less stable as the movement frequency increased. The authors developed an adaptive oscillator model with linear damping to describe the coupled system consisting of the human performer, the visual display, and the control system dynamics. A geometric account of the stability of performance at different relative phases is also presented.

Acceleration↗
PubMed2000

The use of theory in family therapy research: a content analysis of family therapy journals.

Ninety-five studies from Family Process and Journal of Marital and Family Therapy were evaluated with regard to their use of theory. While a majority of the articles were judged to use theory in either an explicit or an implicit manner, 42% did not appear to draw on theory in either the introductory or discussion sections. Studies that used qualitative methods appeared to use theory more frequently and explicitly than those using quantitative methods alone. Systems theory was found to be the most common conceptual framework, followed by feminism. We conclude that the link between theory and research in family therapy needs strengthening and suggest that the role of theory in family therapy be reexamined.

Family Therapy↗
PubMed1995

[From inside to outside? Blind alleys in the discussion of psychoanalysis and society].

The attempt first instituted by Freud to use the instruments of psychoanalysis to improve understanding not only of the individual but also of society as a whole has a long tradition, particularly in Germany. Reviewing the last thirty years of discourse on the range of the applicability of psychoanalysis in this context, the author comes to the conclusion that the fruits of this discussion are negligible. Reiche distinguishes five major lines of discourse to illustrate this failure to establish the relevance of a psychoanalytic approach to illuminating the "out-side" world: the first is one of assimilation and desiccation, reference here being to psychoanalytic culture critique; the second a pathological reaction of collective grieving bound up with the Critical Theory; the third the aggressive rebuffs levelled at psychoanalytic insights by systems theory; the fourth a line of devaluation and usurpation as represented by post-structuralism and deconstructionism. In the fifth and final strand of psychoanalytic application discourse discernible in the theory of communicative action, the author discerns a tentative new rapprochement between sociology and psychoanalysis. The author's final conclusion is that psychoanalysis is suitable for the perspective on the inside world, while the outside world is beyond the scope of psychoanalytic theory.

Freudian Theory↗
PubMed1977

Paradigmatic classification of family therapy theories.

This review proposes a method for classifying theories of family therapy in terms of the ideal categories from which they derive. Establishing the relationship between a family-system theory and a more general world view facilitates the identification of unique aspects of theory and lays the groundwork for a theoretically consistent integration of therapy and research.

Communication↗
PubMed2006

Transient and enduring spatial representations under disorientation and self-rotation.

Current theories of environmental cognition typically differentiate between an online, transient, and dynamic system of spatial representation and an offline and enduring system of memory representation. Here the authors present additional evidence for such 2-system theories in the context of the disorientation paradigm introduced by R. F. Wang and E. S. Spelke (2000). Several experiments replicate the finding that disorientation results in a decrease in the precision of people's estimates of relative directions. In contrast to the typical interpretation of this effect as indicating the primacy of a transient spatial system, the present results are generally more consistent with an interpretation of it as indicating a switch from a relatively precise online representation to a relatively coarse enduring one. Further experiments examine the relative precision of transient and enduring representations and show that switching between them does not require disorientation, but can also be produced by self-rotations as small as 135 degrees .

Adult↗