A neural network model of adaptively timed reinforcement learning and hippocampal dynamics

A neural model is described of how adaptively timed reinforcement learning occurs. The adaptive timing circuit is suggested to exist in the hippocampus, and to involve convergence of dentate granule cells on CA3 pyramidal cells, and NMDA receptors. This circuit forms part of a model neural system for the coordinated control of recognition learning, reinforcement learning, and motor learning, whose properties clarify how an animal can learn to acquire a delayed reward. Behavioral and neural data are summarized in support of each processing stage of the system. The relevant anatomical sites are in thalamus, neocortex, hippocampus, hypothalamus, amygdala, and cerebellum. Cerebellar influences on motor learning are distinguished from hippocampal influences on adaptive timing of reinforcement learning. The model simulates how damage to the hippocampal formation disrupts adaptive timing, eliminates attentional blocking, and causes symptoms of medial temporal amnesia. It suggests how normal acquisition of subcortical emotional conditioning can occur after cortical ablation, even though extinction of emotional conditioning is retarded by cortical ablation. The model simulates how increasing the duration of an unconditioned stimulus increases the amplitude of emotional conditioning, but does not change adaptive timing; and how an increase in the intensity of a conditioned stimulus "speeds up the clock", but an increase in the intensity of an unconditioned stimulus does not. Computer simulations of the model fit parametric conditioning data, including a Weber law property and an inverted U property. Both primary and secondary adaptively timed conditioning are simulated, as are data concerning conditioning using multiple interstimulus intervals (ISIs), gradually or abruptly changing ISis, partial reinforcement, and multiple stimuli that lead to time-averaging of responses. Neurobiologically testable predictions are made to facilitate further tests of the model.Air Force Office of Scientific Research (90-0175, 90-0128); Defense Advanced Research Projects Agency (90-0083); National Science Foundation (IRI-87-16960); Office of Naval Research (N00014-91-J-4100

The hippocampus and cerebellum in adaptively timed learning, recognition, and movement

The concepts of declarative memory and procedural memory have been used to distinguish two basic types of learning. A neural network model suggests how such memory processes work together as recognition learning, reinforcement learning, and sensory-motor learning take place during adaptive behaviors. To coordinate these processes, the hippocampal formation and cerebellum each contain circuits that learn to adaptively time their outputs. Within the model, hippocampal timing helps to maintain attention on motivationally salient goal objects during variable task-related delays, and cerebellar timing controls the release of conditioned responses. This property is part of the model's description of how cognitive-emotional interactions focus attention on motivationally valued cues, and how this process breaks down due to hippocampal ablation. The model suggests that the hippocampal mechanisms that help to rapidly draw attention to salient cues could prematurely release motor commands were not the release of these commands adaptively timed by the cerebellum. The model hippocampal system modulates cortical recognition learning without actually encoding the representational information that the cortex encodes. These properties avoid the difficulties faced by several models that propose a direct hippocampal role in recognition learning. Learning within the model hippocampal system controls adaptive timing and spatial orientation. Model properties hereby clarify how hippocampal ablations cause amnesic symptoms and difficulties with tasks which combine task delays, novelty detection, and attention towards goal objects amid distractions. When these model recognition, reinforcement, sensory-motor, and timing processes work together, they suggest how the brain can accomplish conditioning of multiple sensory events to delayed rewards, as during serial compound conditioning.Air Force Office of Scientific Research (F49620-92-J-0225, F49620-86-C-0037, 90-0128); Advanced Research Projects Agency (ONR N00014-92-J-4015); Office of Naval Research (N00014-91-J-4100, N00014-92-J-1309, N00014-92-J-1904); National Institute of Mental Health (MH-42900

A history of biographical research in the United Kingdom

Biograpahical researchers in the United Kingdom have been influenced by symbolic interactionism, feminism, oral history, critical sociology, psychoanalysis and what we term an auto/biographical imagination. The latter involves reflexively situating the researcher and her influence, via power, unconscious processes and writing, into the text and by acknowledging the co-construction of stories. The focus of much research has been on marginalised peoples, as part of a democratising project to bring more diverse voices and stories into the historical or contemporary social record. It is important to avoid too rigid a distinction between mainland Europe and developments in Britain. Collaboration and dialogue have been extensive, across various research networks, including in the European Society for Research in the Education of Adults (ESREA)

An inverter/controller subsystem optimized for photovoltaic applications

Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy

Jean-Paul Sartre's concept of freedom.

Thesis (M.A.)--Boston UniversityThe purpose of this thesis is to present an exposition and interpretation of Jean-Paul Sartre's concept of freedom, as expressed in his major philosophical writings. This purpose calls for a consideration of the relationship between freedom and some of Sartre's other basic ontological concepts. The "other" concepts are those relating specifically to Sartre's theory of consciousness. To explore and make explicit the fundamental structures of consciousness is to take the front door into an understanding of Sartre's concept of freedom. Chapter II shows that the meaning of Sartre's concept of freedom widely diverges from various traditional and popular interpretations of freedom. It is concluded that the term freedom is intimately bound up with Sartre's conception of consciousness and that a consciousness which is free is, first, free because no determining motives affect the activities of consciousness and, second, consciousness is able to choose the "motives" which it pleases. In Chapter III it is learned that the cardinal activity of consciousness is its intentionality, that consciousness is always consciousness of something. The distinction is made between reflective and pre-reflective consciousness. It is further indicated in this chapter Sartre's rejection of a transcendental unifying and individualizing Ego and his replacement of it with a transcendent Ego, which, for Sartre, becomes an object for consciousness like any other object. In Chapter IV Sartre's ontology is developed by an analysis of all that which is not consciousness, or in Sartre's terminology, a being-in-itself. The in-it self is any transcendent object and its being is characterized by a massive, full identity with itself; being-in-itself is self-consistent, uncreated, and neither passivity nor activity. In Chapter V consciousness is identified with being-for-itself. Being-for-itself is empty of content, must make itself be, is its own nothingness, and introduces negations and temporality into the world. Consciousness will never be what it lacks, for its being lies outside, at a distance, and beyond; it is defined as not being that being. Ontologically speaking, man's being is nothingness. Chapter VI identifies Sartre's notion of freedom with the being of consciousness. Thus one meaning of Sartre's notion of freedom takes on an ontological dimension; man is freedom. The other meaning of freedom is assigned to the necessary activity of consciousness. This activity is characterized by the necessary, unceasing, yet interminable, desire of consciousness to choose or assume its own being, its essence. It has been objected by Wilfrid Desan that Sartre has made freedom itself into the essence of man. This thesis concludes, however, that only in defining freedom has Sartre made freedom an essence. Even in this sense, Sartre has made freedom an essence only if one is willing to identify man's ontological "condition" with the traditional notion of a fundamental "nature" of man. Desan further objects that Sartre's notion of "absolute" freedom results in a contradiction since absolute means unlimited, and Sartre's freedom is limited by freedom itself. The thesis concludes that this contradiction may be avoided by simply refraining from calling Sartre's concept of freedom "absolute" and accepting, along with Sartre, the existential condition that freedom is limited by one thing, namely, freedom itself. A final critical evaluation is made concerning the unavoidable conflict between Sartre's philosophy and philosophizing. It is asserted that this conflict is a conflict between fact and definition. It is the conflict between the fact of freedom and Sartre's definition of this fact

Summary Comments

Thank you for asking me to participate in this conference, the first of its kind in the eastern United States. We are glad that some funding from the Renewable Resources Extension Act has helped to make this conference possible. Jim Miller, National Pro-gram Leader for Fish and Wildlife, Extension Service-USDA, provided early impetus in planning the program, and as a member of the conference committee, served as chairman of publicity and encouraged wide participation. We are pleased that, along with SUNY College of Environmental Science and Forestry and the New York Department of Environmental Conservation, the Extension Service, USDA, could join with Cooperative Extension Service at Cornell University to help sponsor this conference

Revitalization of Assemblies of God Churches in Stagnation or Decline

This dissertation examines church revitalization in Assemblies of God churches in the United States experiencing stagnation and decline. It examines a contextualized perspective of various factors, both practical and theological, as well as various approaches that are being utilized in the field. The result is the formulation of an approach to church health from the semiotic perspective of the human body that can be used to diagnose and overcome the pervasive problem of church decline. Section 1 delineates various problems associated with church decline. Statistics and data are used to define the current reality. The problem of church decline will be explored from a Pentecostal/Charismatic perspective, in particular from the perspective of the Assemblies of God through an understanding of their origin and history, particular influences, and distinct theology. Section 2 examines solutions similar to the problem. Church decline in America has been pervasive and sustained for more than forty years. A plethora of strategies have been created to stem the tide of decline on both a micro and macro level. Various models proposed as a solution for decline are examined. Section 3 provides a systematic, semiotic approach to address the growing issue of church decline in order to position churches to embrace revitalization through renewed church health. Sections 4 and 5 describe the creation of a non-fiction book that offers a fresh look at church health as well as prescriptive tools to lead churches into revitalization

Religious Commitment and Meaning in Life

The purpose of this study was to investigate the relationship between meaning or purpose in life as measured by Crumbaugh\u27s Purpose in Life Test, and the degree of religious commitment of college students, with particular interest in the members of the Church of Jesus Christ of Latter-day Saints (LDS). Religious commitment was measured by Hoge\u27s Intrinsic Religious Motivation Scale (IRM). Two hundred and fifty-five undergraduates, 122 males and 132 females, enrolled in introductory psychology and sociology classes at Utah State University during spring quarter, 1975, served as subjects. A two-way analysis of variance calculated separately for the LDS and non-LDS groups was used to test three hypotheses: (1) there will be a significant difference among the mean PIL scores for the high, moderate, and low religious commitment groups (in that order); (2) females will be significantly higher in their sense of purpose in life than males; (3) females will be significantly higher in their sense of purpose in life in all religious commitment groups. Hypothesis 1 was significant beyond the .05 level for the LDS group. A Sheffe test indicated the difference was between the high and the low religious commitment groups only. Hypotheses 2 and 3 were not supported. None of the three hypotheses were supported for the nonLDS group. T-ratios computed between the three corresponding levels of religious commitment for the LDS and non-LDS groups were significant beyond the .05 level. A significant positive relationship for males beyond the .05 level was found between sex and religious commitment. No relationship was found between sex and purpose in life. A significant positive relationship beyond the .05 level was found between religious commitment and purpose in life. No significant differences were found between year in school, marital status, and socioeconomic status on either purpose in life or religious commitment. Significant differences beyond the .05 level were found between religious commitment and church attendance, and between religious commitment and activity in church organizations. It was concluded that the results support the premise that religion can have a significant impact on an individual\u27s sense of purpose in life as defined by Frankl (1963), particularly if the individual\u27s religion encourages active involvement on the part of the individual. The effect is especially strong if high religious belief, high religious participation, and social activity outside of church occur together