bluuebunny/crossref_metadata_2025 huggingface dataset:
CATEGORICAL DATA ANALYSIS IN PUBLIC HEALTH
Authors: Preisser John S. , Koch Gary G.
Published: July 2002

▪ Abstract  A greater variety of categorical data methods are used today than 15 years ago. This article surveys categorical data methods widely applied in public health research. Whereas large sample chi-square methods, logistic regression analysis, and weighted least squares modeling of repeated measures once comprised the primary analytic tools for categorical data problems, today's methodology is comprised of a much broader range of tools made available by increasing computational efficiency. These include computational algorithms for exact inference of small samples and sparsely distributed data, conditional logistic regression for modeling highly stratified data, and generalized estimating equations for cluster samples. The latter, in particular, has found wide use in modeling the marginal probabilities of correlated counted, binary, and multinomial outcomes. The various methods are illustrated with examples including a study of the prevalence of cerebral palsy in very low birthweight infants and a study of cancer screening in primary care settings.
Religion and Health: Public Health Research and Practice
Authors: Chatters Linda M.
Published: July 2002

▪ Abstract  Research examining the relationships between religion and the health of individuals and populations has become increasingly visible in the social, behavioral, and health sciences. Systematic programs of research investigate religious phenomena within the context of coherent theoretical and conceptual frameworks that describe the causes and consequences of religious involvement for health outcomes. Recent research has validated the multidimensional aspects of religious involvement and investigated how religious factors operate through various biobehavioral and psychosocial constructs to affect health status through proposed mechanisms that link religion and health. Methodological and analytical advances in the field permit the development of more complex models of religion's effects, in keeping with proposed theoretical explanations. Investigations of religion and health have ethical and practical implications that should be addressed by the lay public, health professionals, the research community, and the clergy. Future research directions point to promising new areas of investigation that could bridge the constructs of religion and health.
The Social Ecology of Child Health and Well-Being
Authors: Earls Felton , Carlson Mary
Published: July 2002

▪ Abstract  The term social ecology refers to the nested arrangement of family, school, neighborhood, and community contexts in which children grow up. In this chapter, new directions in public health science as reflected in the theoretical and methodological implications of the concept are explored. The contributions of this ecologically oriented approach to child health practice, designed as it is from a health promotions perspective, are considered. A critique of the term social capital is also presented because of its growing popularity in matters of child health. The point is made that application of this vague term carries the serious risk of misspecifying social phenomena. Future trends in the promotion of child well-being are in a position to flourish given the confluence of advances in theory, methods, and analytical capacity. The capacity to benefit children is also enhanced as public health science aims to translate the principles of child rights into health practice and policy.
Minisymposium on Obesity: Overview and Some Strategic Considerations
Authors: Kumanyika Shiriki K
Published: July 2002

▪ Abstract  The high and still increasing prevalence of obesity in US children, adolescents, and adults poses a major economic and health threat to our society. The three reviews in this minisymposium on obesity explore the health issues by: 1) describing the public health impact of obesity; 2) examining the multiple and complex environmental influences on eating and physical activity patterns; and 3) considering how the development of obesity during childhood and adolescence can be prevented through interventions in school, family, and primary care settings. This overview explains the importance, for effective long-term obesity prevention and control, of intersectoral policy and environmental initiatives—in addition to behavior change approaches aimed at individuals. The need for public health professionals to influence and operate within a variety of non-health sectors such as transportation, education, urban planning, and commerce may be seen as the greatest barrier but may also be the greatest opportunity.
The Public Health Impact of Obesity
Authors: Visscher Tommy LS , Seidell Jacob C
Published: July 2002

▪ Abstract  The increase in obesity worldwide will have an important impact on the global incidence of cardiovascular disease, type 2 diabetes mellitus, cancer, osteoarthritis, work disability, and sleep apnea. Obesity has a more pronounced impact on morbidity than on mortality. Disability due to obesity-related cardiovascular diseases will increase particularly in industrialized countries, as patients survive cardiovascular diseases in these countries more often than in nonindustrialized countries. Disability due to obesity-related type 2 diabetes will increase particularly in industrializing countries, as insulin supply is usually insufficient in these countries. As a result, in these countries, an increase in disabling nephropathy, arteriosclerosis, neuropathy, and retinopathy is expected. Increases in the prevalence of obesity will potentially lead to an increase in the number of years that subjects suffer from obesity-related morbidity and disability. A 1% increase in the prevalence of obesity in such countries as India and China leads to 20 million additional cases of obesity. Prevention programs will stem the obesity epidemic more efficiently than weight-loss programs. However, only a few prevention programs have been developed or implemented, and the success rates reported to date have been low. Obesity prevention programs should be high on the scientific and political agenda in both industrialized and industrializing countries.
Market Transition and Societal Transformation in Reforming State Socialism
Authors: Nee Victor , Matthews Rebecca
Published: July 2002

The far-reaching institutional change and societal transformation occurring in former state-socialist societies have attracted new social science interest in transition economies. This chapter reviews recent research on China, highlighting the theoretical arguments and findings of general interest to social scientists. The paper argues that a paradigm shift is taking place within research on China, from state-centered analysis to a theoretical approach that locates causal forces within a macrosocietal framework. Within a macrosocietal framework, state socialism is viewed as a distinctive institutional arrangement in which society, economy, and the state are integrated through society-wide redistributive arrangements. Forces in economic and political change emanate not only from political actors but from economic and social actors as well. The chapter reviews work in which a macrosocietal approach is used to address stratification, societal transformation, and marketization in reforming Chinese state socialism.
Politics and Culture: A Less Fissured Terrain
Authors: Berezin Mabel
Published: July 2002

In the past few years, the area of politics and culture has moved from the margins of cultural inquiry to its center as evidenced by the number of persons who identify themselves as working within the area and by its growing institutionalization within sociology. “Politics and culture” suggests that each term constitutes an autonomous social realm; whereas “political culture” suggests the boundaries of cultural action within which ordinary politics occurs. Bourdieu's emphasis on boundary making, Foucault's disciplinary mechanisms, and Habermas's conception of the public are setting the research agenda of scholars who focus on macro-level social change. Interdisciplinary dialogues are emerging, conducted on a landscape of historical and contemporary empirical research. Four sub-areas have crystallized: first, political culture, which focuses on problems of democratization and civil society; second, institutions, which includes law, religion, the state, and citizenship; third, political communication and meaning; and fourth, cultural approaches to collective action. Promising directions for future work are historical ethnographies, participant observation and interview studies of political communication, and studies of political mobilization that examine how emotion operates in politics. Paradigms are not yet firm within this area, suggesting that politics and culture is a disciplinary site of theoretical, methodological, and empirical innovation.
Social Memory Studies: From “Collective Memory” to the Historical Sociology of Mnemonic Practices
Authors: Olick Jeffrey K. , Robbins Joyce
Published: July 2002

Despite substantial work in a variety of disciplines, substantive areas, and geographical contexts, social memory studies is a nonparadigmatic, transdisciplinary, centerless enterprise. To remedy this relative disorganization, we (re-)construct out of the diversity of work addressing social memory a useful tradition, range of working definitions, and basis for future work. We trace lineages of the enterprise, review basic definitional disputes, outline a historical approach, and review sociological theories concerning the statics and dynamics of social memory.
Volunteering
Authors: Wilson John
Published: July 2002

Volunteering is any activity in which time is given freely to benefit another person, group or cause. Volunteering is part of a cluster of helping behaviors, entailing more commitment than spontaneous assistance but narrower in scope than the care provided to family and friends. Although developed somewhat independently, the study of volunteerism and of social activism have much in common. Since data gathering on volunteering from national samples began about a quarter of a century ago, the rate for the United States has been stable or, according to some studies, rising slightly. Theories that explain volunteering by pointing to individual attributes can be grouped into those that emphasize motives or self-understandings on the one hand and those that emphasize rational action and cost-benefit analysis on the other. Other theories seek to complement this focus on individual level factors by pointing to the role of social resources, specifically social ties and organizational activity, as explanations for volunteering. Support is found for all theories, although many issues remained unresolved. Age, gender and race differences in volunteering can be accounted for, in large part, by pointing to differences in self-understandings, human capital, and social resources. Less attention has been paid to contextual effects on volunteering and, while evidence is mixed, the impact of organizational, community, and regional characteristics on individual decisions to volunteer remains a fruitful field for exploration. Studies of the experience of volunteering have only just begun to plot and explain spells of volunteering over the life course and to examine the causes of volunteer turnover. Examining the premise that volunteering is beneficial for the helper as well as the helped, a number of studies have looked at the impact of volunteering on subjective and objective well-being. Positive effects are found for life-satisfaction, self-esteem, self-rated health, and for educational and occupational achievement, functional ability, and mortality. Studies of youth also suggest that volunteering reduces the likelihood of engaging in problem behaviors such as school truancy and drug abuse.
Multilevel Modeling for Binary Data
Authors: Guo Guang , Zhao Hongxin
Published: July 2002

We review some of the work of the past ten years that applied the multilevel logit model. We attempt to provide a brief description of the hypothesis tested, the hierarchical data structure analyzed, and the multilevel data source for each piece of work we have reviewed. We have also reviewed the technical literature and worked out two examples on multilevel models for binary outcomes. The review and examples serve two purposes: First, they are designed to assist in all aspects of working with multilevel models for binary outcomes, including model conceptualization, model description for a research report, understanding of the structure of required multilevel data, estimation of the model via a generally available statistical package, and interpretation of the results. Second, our examples contribute to the evaluation of the approximation procedures for binary multilevel models that have been implemented for general public use.
A Space for Place in Sociology
Authors: Gieryn Thomas F.
Published: July 2002

Sociological studies sensitive to the issue of place are rarely labeled thus, and at the same time there are far too many of them to fit in this review. It may be a good thing that this research is seldom gathered up as a “sociology of place,” for that could ghettoize the subject as something of interest only to geographers, architects, or environmental historians. The point of this review is to indicate that sociologists have a stake in place no matter what they analyze, or how: The works cited below emplace inequality, difference, power, politics, interaction, community, social movements, deviance, crime, life course, science, identity, memory, history. After a prologue of definitions and methodological ruminations, I ask: How do places come to be the way they are, and how do places matter for social practices and historical change?
Conceptualizing Stigma
Authors: Link Bruce G. , Phelan Jo C.
Published: July 2002

Social science research on stigma has grown dramatically over the past two decades, particularly in social psychology, where researchers have elucidated the ways in which people construct cognitive categories and link those categories to stereotyped beliefs. In the midst of this growth, the stigma concept has been criticized as being too vaguely defined and individually focused. In response to these criticisms, we define stigma as the co-occurrence of its components–labeling, stereotyping, separation, status loss, and discrimination–and further indicate that for stigmatization to occur, power must be exercised. The stigma concept we construct has implications for understanding several core issues in stigma research, ranging from the definition of the concept to the reasons stigma sometimes represents a very persistent predicament in the lives of persons affected by it. Finally, because there are so many stigmatized circumstances and because stigmatizing processes can affect multiple domains of people's lives, stigmatization probably has a dramatic bearing on the distribution of life chances in such areas as earnings, housing, criminal involvement, health, and life itself. It follows that social scientists who are interested in understanding the distribution of such life chances should also be interested in stigma.
Hate Crime: An Emergent Research Agenda
Authors: Green Donald P. , McFalls Laurence H. , Smith Jennifer K.
Published: July 2002

Hate crime is difficult to define, measure, and explain. After summarizing some of the leading conceptual issues and theoretical perspectives, we discuss the practical difficulties associated with data collection. Although the research literature remains small and largely descriptive, recent studies have begun to relate hate crime patterns to economic cycles, population flows, and changes in the political environment. The task ahead is to extend these analyses to other settings and levels of aggregation.
Obligatory Role of Cyclic Adenosine Monophosphate Response Element in Cyclooxygenase-2 Promoter Induction and Feedback Regulation by Inflammatory Mediators
Authors: Schroer Karsten , Zhu Ying , Saunders Michael A. , Deng Wu-Guo , Xu Xiao-Ming , Meyer-Kirchrath Jutta , Wu Kenneth K.
Published: July 2002

Background

—

Cyclooxygenase-2 (COX-2) plays a key role in human inflammatory disorders such as vascular inflammation. COX-2 promoter activity is induced by proinflammatory mediators, but the role of cyclic adenosine monophosphate response element (CRE) in promoter stimulation remains unclear.

Methods and Results

—

Transient transfection of a 0.9-kb COX-2 promoter fragment bearing CRE mutation abrogated COX-2 promoter activity induced by proinflammatory mediators in human endothelial cells and fibroblasts. Dual mutations of CRE and an upstream CCAAT/enhancer binding protein (C/EBP) site did not have an additional effect. Binding of CREB-2, ATF-2, USF-2, and c-Jun transactivators to a wild-type and CRE-mutated oligonucleotide was analyzed by a novel DNA-binding assay. CREB-2 and ATF-2 in nuclear extracts of unstimulated endothelial cells bound to CRE, whereas USF-2 and c-Jun or c-Fos bound to non-CRE sites. CREB-2 and c-Fos binding was increased by phorbol 12-myristate 13-acetate but not tumor necrosis factor-α. The binding assay and chromatin immunoprecipitation revealed binding of P300 coactivator to the COX-2 promoter region.

Conclusions

—

CRE plays an obligatory role in COX-2 promoter activation by diverse stimuli. CREB-2 and ATF-2 bound to CRE serve as an anchor for P300 interaction with upstream transactivators and downstream transcription machinery.
Expression of a Functionally Active gp91phox-Containing Neutrophil-Type NAD(P)H Oxidase in Smooth Muscle Cells From Human Resistance Arteries
Authors: Touyz Rhian M. , Chen Xin , Tabet Fatiha , Yao Guoying , He Gang , Quinn Mark T. , Pagano Patrick J. , Schiffrin Ernesto L.
Published: July 2002

A major source of vascular smooth muscle cell (VSMC) superoxide is NAD(P)H oxidase. However, the molecular characteristics and regulation of this enzyme are unclear. We investigated whether VSMCs from human resistance arteries (HVSMCs) possess a functionally active, angiotensin II (Ang II)–regulated NAD(P)H oxidase that contains neutrophil oxidase subunits, including p22phox, gp91phox, p40phox, p47phox, and p67phox. mRNA expression of gp91phox homologues, nox1 and nox4, was also assessed in HVSMCs, human aortic smooth muscle cells, and rat VSMCs. HVSMCs were obtained from resistance arteries from gluteal biopsies of healthy subjects. gp91phox and nox4, but not nox1, were detected in HVSMCs. Nox1 and nox4, but not gp91phox, were expressed in human aortic smooth muscle cells and rat VSMCs. All NAD(P)H oxidase subunits were present in HVSMCs as detected by reverse transcriptase–polymerase chain reaction and immunoblotting. Ang II increased NAD(P)H oxidase subunit abundance. These effects were inhibited by cycloheximide. Acute Ang II stimulation (10 to 15 minutes) increased p47phox serine phosphorylation and induced p47phox and p67phox translocation. This was associated with NAD(P)H oxidase activation. In cells transfected with gp91phox antisense oligonucleotides, Ang II–mediated actions were abrogated. NADPH-induced superoxide generation was reduced by gp91ds-tat and apocynin, inhibitors of p47phox-gp91phox interactions. Our results suggest that HVSMCs possess a functionally active gp91phox-containing neutrophil-like NAD(P)H oxidase. Ang II regulates the enzyme by inducing phosphorylation of p47phox, translocation of cytosolic subunits, and de novo protein synthesis. These novel findings provide insight into the molecular regulation of NAD(P)H oxidase by Ang II in HVSMCs. Furthermore, we identify differences in gp91phox homologue expression in VSMCs from rats and human small and large arteries.
Whence American Internationalism
Authors: Legro Jeffrey W.
Published: July 2002

One of the most important puzzles of twentieth-century international relations is why the American conception of security vis-à-vis the European Powers shifted from unilateralism to internationalism after World War II but not after World War I. In this article I document that this shift was measurably one of collective ideas and explain the transformation. Scholarship on the sea change in American global thinking has been hampered by the lack of attention to the broader issues of when and why collective ideas change. To address this gap I offer a general framework to account for ideational change: I highlight the interaction between collective ideas and events that allows individuals and societies to overcome barriers to ideational change in some circumstances but not others. This argument clarifies the otherwise puzzling development of American ideas and offers a template for understanding change in other areas.
Trust, Reassurance, and Cooperation
Authors: Kydd Andrew
Published: July 2002

Many scholars have argued that mistrust can prevent cooperation. These arguments often fail to adequately address the possibility that states can take steps to reassure each other, build trust, and thereby avoid conflict. I present a rational choice theory of reassurance focusing on costly signals and identify the conditions under which players can use costly signals to reassure the other side. The central result is that reassurance will be possible between trustworthy players in equilibrium if trustworthy actors are more willing to take risks to attain mutual cooperation than untrustworthy actors. I discuss the implications of the model in the context of the reassurance strategies pursued by Soviet leader Mikhail Gorbachev at the end of the Cold War.
The Concept of Legalization
Authors: Abbott Kenneth W. , Keohane Robert O. , Moravcsik Andrew , Slaughter Anne-Marie , Snidal Duncan
Published: July 2002

We develop an empirically based conception of international legalization to show how law and politics are intertwined across a wide range of institutional forms and to frame the analytic and empirical articles that follow in this volume. International legalization is a form of institutionalization characterized by three dimensions: obligation, precision, and delegation. Obligation means that states are legally bound by rules or commitments and therefore subject to the general rules and procedures of international law. Precision means that the rules are definite, unambiguously defining the conduct they require, authorize, or proscribe. Delegation grants authority to third parties for the implementation of rules, including their interpretation and application, dispute settlement, and (possibly) further rule making. These dimensions are conceptually independent, and each is a matter of degree and gradation. Their various combinations produce a remarkable variety of international legalization. We illustrate a continuum ranging from “hard” legalization (characteristically associated with domestic legal systems) through various forms of “soft” legalization to situations where law is largely absent. Most international legalization lies between the extremes, where actors combine and invoke varying degrees of obligation, precision, and delegation to create subtle blends of politics and law.
Why Comply? Social Learning and European Identity Change
Authors: Checkel Jeffrey T.
Published: July 2002

Why do agents comply with the norms embedded in regimes and international institutions? Scholars have proposed two competing answers to this compliance puzzle, one rationalist, the other constructivist. Rationalists emphasize coercion, cost/benefit calculations, and material incentives; constructivists stress social learning, socialization, and social norms. Both schools, however, explain important aspects of compliance. To build a bridge between them, I examine the role of argumentative persuasion and social learning. This makes explicit the theory of social choice and interaction implicit in many constructivist compliance studies, and it broadens rationalist arguments about the instrumental and noninstrumental processes through which actors comply. I argue that domestic politics—in particular, institutional and historical contexts—delimit the causal role of persuasion/social learning, thus helping both rationalists and constructivists to refine the scope of their compliance claims. To assess the plausibility of these arguments, I examine why states comply with new citizenship/membership norms promoted by European regional organizations.
Wage Bargaining, Central Bank Independence, and the Real Effects of Money
Authors: Iversen Torben
Published: July 2002

The effects of financial capital mobility on monetary policy autonomy are relatively well understood, but the importance of particular monetary regimes in distinct national-institutional settings is not. This article is a theoretical and empirical exploration of the effects of monetary policy regimes on unemployment in different national wage-bargaining settings. Based on a rational expectations, two-stage game of the interaction between the wage behavior of labor unions and the monetary policies of governments, I argue that monetary policies have real (employment) effects in all but the most decentralized bargaining systems. Specifically, in intermediately centralized bargaining systems a credible government commitment to a nonaccommodating monetary policy rule will deter militant wage behavior with salutary effects on unemployment. In highly centralized systems, by contrast, restrictive monetary policies will clash with unions' pursuit of wage-distributive goals and produce inferior employment performance. Only in highly fragmented bargaining systems is money “neutral” in the sense that employment performance is unaffected by monetary regimes. The model has clear consequences for the optimal design of central banks and collective bargaining arrangements and suggests new ways to study institutional change (hereunder the causal effect of increasingly globalized capital markets). The argument is supported by pooled time-series data for fifteen OECD countries over a twenty-one-year period.
The Sociology of a Not So International Discipline: American and European Developments in International Relations
Authors: Wæver Ole
Published: July 2002

The international relations (IR) discipline is dominated by the American research community. Data about publication patterns in leading journals document this situation as well as a variance in theoretical orientations. IR is conducted differently in different places. The main patterns are explained through a sociology of science model that emphasizes the different nineteenth-century histories of the state, the early format of social science, and the institutionalized delineation among the different social sciences. The internal social and intellectual structure of American IR is two-tiered, with relatively independent subfields and a top layer defined by access to the leading journals (on which IR, in contrast to some social sciences, has a high consensus). The famous successive “great debates” serve an important function by letting lead theorists focus and structure the whole discipline. IR in France, Germany, and the United Kingdom has historically been structured differently, often with power vested more locally. American IR now moves in a direction that undermines its global hegemony. The widespread turn to rational choice privileges a reintegration (and status-wise rehabilitation) with the rest of political science over attention to IR practices elsewhere. This rationalistic turn is alien to Europeans, both because their IR is generally closer to sociology, philosophy, and anthropology, and because the liberal ontological premises of rational choice are less fitting to European societies. Simultaneously, European IR is beginning to break the local power bastions and establish independent research communities at a national or, increasingly, a European level. As American IR turns from global hegemony to national professionalization, IR becomes more pluralistic.
Archaeology and Probate Inventories in the Study of Eighteenth-Century Life
Authors: Bedell John
Published: July 2002

Comparison of probate inventories with the findings of archeological research shows that neither, by itself, gives a complete account of eighteenth-century material culture. Data from excavations and inventory studies in Delaware illustrate how these sources can be used together to gain a better understanding of life. Archaeology provides particularly important data on poor households.
QR Obeys Superiority: Frozen Scope and ACD
Authors: Bruening Benjamin
Published: July 2002

The phenomenon of “frozen scope” in double object and spray-load constructions is shown to hold robustly across contexts, constructions, and quantifier types. Nevertheless, frozen scope is not absolute, holding only between two objects but not between an object and a subject or an object and some other operator. The rigidity of two object quantifiers follows the pattern of multiple instances of movement cross linguistically (multiple wh-movement, multiple A-scrambling, multiple object shift): movement paths cross, recreating the hierarchical order of the moving elements (Richards 1997). Hypothesizing that quantifier scope is derived by quantifier-specific syntactic movement, movement that is constrained in the same way as other types of movement, permits these phenomena to be unified under accounts of Relativized Minimality effects generally.
The Maturation of Grammatical Principles: Evidence from Russian Unaccusatives
Authors: Babyonyshev Maria , Ganger Jennifer , Pesetsky David , Wexler Kenneth
Published: July 2002

This article tests the hypothesis that young children have a maturational difficulty with A-chain formation that makes them unable to represent unaccusative verbs in an adultlike fashion. We report the results of a test of children's performance on the genitive-of-negation construction in Russian, which, for adults, is an “unaccusativity diagnostic,” since genitive case is allowed to appear on the underlying direct object argument of unaccusatives as well as on direct objects of standard transitive verbs within the scope of negation. We show that although, Russian children know the properties of the construction, they have notable difficulty using it with unaccusative verbs. Since the input evidence for genitive of negation with unaccusative verbs is quite robust, we interpret our results as support for the hypothesis.
On Coreferring: Coreference in MUC and Related Annotation Schemes
Authors: Deemter Kees van , Kibble Rodger
Published: July 2002

In this paper, it is argued that “coreference” annotations, as performed in the MUC community for example, go well beyond annotation of the relation of coreference proper. As a result, it is not always clear what semantic relation these annotations are encoding. The paper discusses a number of problems with these annotations and concludes that rethinking of the coreference task is needed before the task is expanded. In particular, it suggests a division of labor whereby annotation of the coreference relation proper is separated from other tasks such as annotation of bound anaphora and of the relation between a subject and a predicative NP.
A Statistical Model for Word Discovery in Transcribed Speech
Authors: Venkataraman Anand
Published: July 2002

A statistical model for segmentation and word discovery in continuous speech is presented. An incremental unsupervised learning algorithm to infer word boundaries based on this model is described. Results are also presented of empirical tests showing that the algorithm is competitive with other models that have been used for similar tasks.
Capacity Theory as a Model of Cortical Behavior
Authors: Handy Todd C.
Published: July 2002

Growing evidence suggests that a more complete understanding of cortical function requires developing cognitive models that are predictive of multivariate neural behavior (e.g., Raichle, 2000; Shulman et al., 1997). Towards this end, one approach is to interpret population-specific activity in cortex from the perspective of capacity theories of selective attention (e.g., Handy, Hopfinger, & Mangun, in press). In brief, the model is founded on the ideas that (1) processing capacity is limited and (2) different processes may draw on different capacities (e.g., Boles & Law 1998; Polson & Friedman, 1988; see Kramer & Spinks, 1991). Testable hypotheses are then based on whether manipulations of process-specific load will lead to negative or positive covariation between different function-related clusters of activation in cortex—the predicted pattern depends on whether or not the clusters in question are assumed to share a common processing capacity. Expanding on these ideas, the current article addresses several recent issues that have arisen in the effort to apply capacity theory to the study of cortical function.
Procedural Learning in Broca's Aphasia: Dissociation between the Implicit Acquisition of Spatio-Motor and Phoneme Sequences
Authors: Goschke Thomas , Friederici Angela D. , Kotz Sonja A. , van Kampen Anja
Published: July 2002

Procedural learning of spatio-motor and phoneme sequences was investigated in patients with Broca's and Wernick's aphasia and age-matched controls. In Experiment 1, participants performed a standard serial reaction task (SRT) in which they manually responded to a repeating sequence of stimulus locations. Both Broca's and Wernick's aphasics showed intact sequence learning, as indicated by a reliable response time (RT) cost when the repeating sequence was swithched to a random sequence. In Experiment 2, Broca's aphasics and controls performed a new serial search task (SST), which allowed us to investigate the learning of a spatio-motor sequence and a phoneme sequence independently from each other. On each trial, four letters were presented visually, followed by a single auditorily presented letter. Participants had to press one of four response keys to indicate the location of the auditory letter in the visual display. The arrangement of the visual letters was changed from trial to trial such that either the key-presses or the auditory letters followed a repeating pattern, while the other sequence was random. While controls learned both the key-press and the phoneme sequences, Broca's aphasics were selectively impaired in learning the phoneme sequence. This dissociation between learning of spatio-motor and phoneme sequences supports the assumption that partially separable brain systems are involved in proceedural learning of differenct types of sequential structures.
Phonological Processing in Visual Rhyming: A Developmental ERP Study
Authors: Grossi Giordana , Coch Donna , Coffey-Corina Sharon , Holcomb Phillip J. , Neville Helen J.
Published: July 2002

We employed a visual rhyming priming paradigm to characterize the development of brain systems important for phonological processing in reading. We studied 109 right-handed, native English speakers within eight age groups: 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20, and 21-23. Participants decided whether two written words (prime-target) rhymed (JUICE-MOOSE) or not (CHAIR-MOOSE). In similar studies of adults, two main event-related potential (ERP) effects have been described: a negative slow wave to primes, larger over anterior regions of the left hemisphere and hypothesized to index rehearsal of the primes, and a negative deflection to targets, peaking at 400-450 msec, maximal over right temporal-parietal regions, larger for nonrhyming than rhyming targets, and hypothesized to index phonological matching. In this study, these two ERP effects were observed in all age groups; however, the two effects showed different developmental timecourses. On the one hand, the frontal asymmetry to primes increased with age; moreover, this asymmetry was correlated with reading and spelling scores, even after controlling for age. On the other hand, the distribution and onset of the more posterior rhyming effect (RE) were stable across age groups, suggesting that phonological matching relied on similar neural systems across these ages. Behaviorally, both reaction times and accuracy improved with age. These results suggest that different aspects of phonological processing rely on different neural systems that have different developmental timecourses.
Posterior Corpus Callosum and Interhemispheric Transfer of Somatosensory Information: An fMRI and Neuropsychological Study of a Partially Callosotomized Patient
Authors: Fabri Mara , Polonara Gabriele , Pesce Maria Del , Quattrini Angelo , Salvolini Ugo , Manzoni Tullio
Published: July 2002

Interhemispheric somatosensory transfer was studied by functional magnetic resonance imaging (fMRI) and neuropsychological tests in a patient who underwent resection of the corpus callosum (CC) for drug-resistant epilepsy in two stages. The first resection involved the anterior half of the body of CC and the second, its posterior half and the splenium. For the fMRI study, the hand was stimulated with a rough sponge. The neuropsychological tests included: Tactile Naming Test (TNT), Same-Different Recognition Test (SDRT), and Tactile Finger Localization Test (intra- and intermanual tasks, TFLT). The patient was studied 1 week before and then 6 months and 1 year after the second surgery. Before this operation, unilateral tactile stimulation of either hand activated contralaterally the first (SI) and second (SII) somatosensory areas and the posterior parietal (PP) cortex, and SII and PP cortex ipsilaterally. All three tests were performed without errors. In both postoperative sessions, somatosensory activation was observed in contralateral SI, SII, and PP cortex, but not in ipsilateral SII and PP cortex. Performance was 100% correct in the TNT for the right hand, but below chance for the left; in the other tests, it was below chance except for TFLT in the intramanual task. This case provides the direct demonstration that activation of SII and PP cortex to stimulation of the ipsilateral hand and normal interhemispheric transfer of tactile information require the integrity of the posterior body of the CC.
A Neural Network Model of Lateralization during Letter Identification
Authors: Shevtsova Natalia , Reggia James A.
Published: July 2002

The causes of cerebral lateralization of cognitive and other functions are currently not well understood. To investigate one aspect of function lateralization, a bihemispheric neural network model for a simple visual identification task was developed that has two parallel interacting paths of information processing. The model is based on commonly accepted concepts concerning neural connectivity, activity dynamics, and synaptic plasticity. A combination of both unsupervised (Hebbian) and supervised (Widrow-Hoff) learning rules is used to train the model to identify a small set of letters presented as input stimuli in the left visual hemifield, in the central position, and in the right visual hemifield. Each visual hemifield projects onto the contralateral hemisphere, and the two hemispheres interact via a simulated corpus callosum. The contribution of each individual hemisphere to the process of input stimuli identification was studied for a variety of underlying asymmetries. The results indicate that multiple asymmetries may cause lateralization. Lateralization occurred toward the side having larger size, higher excitability, or higher learning rate parameters. It appeared more intensively with strong inhibitory callosal connections, supporting the hypothesis that the corpus callosum plays a functionally inhibitory role. The model demonstrates clearly the dependence of lateralization on different hemisphere parameters and suggests that computational models can be useful in better understanding the mechanisms underlying emergence of lateralization.
Neural Coding: Higher-Order Temporal Patterns in the Neurostatistics of Cell Assemblies
Authors: Martignon Laura , Deco Gustavo , Laskey Kathryn , Diamond Mathew , Freiwald Winrich , Vaadia Eilon
Published: July 2002

Recent advances in the technology of multiunit recordings make it possible to test Hebb's hypothesis that neurons do not function in isolation but are organized in assemblies. This has created the need for statistical approaches to detecting the presence of spatiotemporal patterns of more than two neurons in neuron spike train data. We mention three possible measures for the presence of higher-order patterns of neural activation—coefficients of log-linear models, connected cumulants, and redundancies—and present arguments in favor of the coefficients of log-linear models. We present test statistics for detecting the presence of higher-order interactions in spike train data by parameterizing these interactions in terms of coefficients of log-linear models. We also present a Bayesian approach for inferring the existence or absence of interactions and estimating their strength. The two methods, the frequentist and the Bayesian one, are shown to be consistent in the sense that interactions that are detected by either method also tend to be detected by the other. A heuristic for the analysis of temporal patterns is also proposed. Finally, a Bayesian test is presented that establishes stochastic differences between recorded segments of data. The methods are applied to experimental data and synthetic data drawn from our statistical models. Our experimental data are drawn from multiunit recordings in the prefrontal cortex of behaving monkeys, the somatosensory cortex of anesthetized rats, and multiunit recordings in the visual cortex of behaving monkeys.
The Bayesian Evidence Scheme for Regularizing Probability-Density Estimating Neural Networks
Authors: Husmeier Dirk
Published: July 2002

Training probability-density estimating neural networks with the expectation-maximization (EM) algorithm aims to maximize the likelihood of the training set and therefore leads to overfitting for sparse data. In this article, a regularization method for mixture models with generalized linear kernel centers is proposed, which adopts the Bayesian evidence approach and optimizes the hyperparameters of the prior by type II maximum likelihood. This includes a marginalization over the parameters, which is done by Laplace approximation and requires the derivation of the Hessian of the log-likelihood function. The incorporation of this approach into the standard training scheme leads to a modified form of the EM algorithm, which includes a regularization term and adapts the hyperparameters on-line after each EM cycle. The article presents applications of this scheme to classification problems, the prediction of stochastic time series, and latent space models.
A Bayesian Committee Machine
Authors: Tresp Volker
Published: July 2002

The Bayesian committee machine (BCM) is a novel approach to combining estimators that were trained on different data sets. Although the BCM can be applied to the combination of any kind of estimators, the main foci are gaussian process regression and related systems such as regularization networks and smoothing splines for which the degrees of freedom increase with the number of training data. Somewhat surprisingly, we find that the performance of the BCM improves if several test points are queried at the same time and is optimal if the number of test points is at least as large as the degrees of freedom of the estimator. The BCM also provides a new solution for on-line learning with potential applications to data mining. We apply the BCM to systems with fixed basis functions and discuss its relationship to gaussian process regression. Finally, we show how the ideas behind the BCM can be applied in a non-Bayesian setting to extend the input-dependent combination of estimators.
SMEM Algorithm for Mixture Models
Authors: Ueda Naonori , Nakano Ryohei , Ghahramani Zoubin , Hinton Geoffrey E.
Published: July 2002

We present a split-and-merge expectation-maximization (SMEM) algorithm to overcome the local maxima problem in parameter estimation of finite mixture models. In the case of mixture models, local maxima often involve having too many components of a mixture model in one part of the space and too few in another, widely separated part of the space. To escape from such configurations, we repeatedly perform simultaneous split-and-merge operations using a new criterion for efficiently selecting the split-and-merge candidates. We apply the proposed algorithm to the training of gaussian mixtures and mixtures of factor analyzers using synthetic and real data and show the effectiveness of using the split- and-merge operations to improve the likelihood of both the training data and of held-out test data. We also show the practical usefulness of the proposed algorithm by applying it to image compression and pattern recognition problems.
A Model for Fast Analog Computation Based on Unreliable Synapses
Authors: Maass Wolfgang , Natschläger Thomas
Published: July 2002

We investigate through theoretical analysis and computer simulations the consequences of unreliable synapses for fast analog computations in networks of spiking neurons, with analog variables encoded by the current firing activities of pools of spiking neurons. Our results suggest a possible functional role for the well-established unreliability of synaptic transmission on the network level. We also investigate computations on time series and Hebbian learning in this context of space-rate coding in networks of spiking neurons with unreliable synapses.
Natural Discriminant Analysis Using Interactive Potts Models
Authors: Wu Jiann-Ming
Published: July 2002

Natural discriminant analysis based on interactive Potts models is developed in this work. A generative model composed of piece-wise multivariate gaussian distributions is used to characterize the input space, exploring the embedded clustering and mixing structures and developing proper internal representations of input parameters. The maximization of a log-likelihood function measuring the fitness of all input parameters to the generative model, and the minimization of a design cost summing up square errors between posterior outputs and desired outputs constitutes a mathematical framework for discriminant analysis. We apply a hybrid of the mean-field annealing and the gradient-descent methods to the optimization of this framework and obtain multiple sets of interactive dynamics, which realize coupled Potts models for discriminant analysis. The new learning process is a whole process of component analysis, clustering analysis, and labeling analysis. Its major improvement compared to the radial basis function and the support vector machine is described by using some artificial examples and a real-world application to breast cancer diagnosis.
Self-Organization in the Basal Ganglia with Modulation of Reinforcement Signals
Authors: Nakahara Hiroyuki , Amari Shun-ichi , Hikosaka Okihide
Published: July 2002

Self-organization is one of fundamental brain computations for forming efficient representations of information. Experimental support for this idea has been largely limited to the developmental and reorganizational formation of neural circuits in the sensory cortices. We now propose that self-organization may also play an important role in short-term synaptic changesinreward-drivenvoluntarybehaviors.Ithasrecentlybeenshown that many neurons in the basal ganglia change their sensory responses flexibly in relation to rewards. Our computational model proposes that the rapid changes in striatal projection neurons depend on the subtle balance between the Hebb-type mechanisms of excitation and inhibition, which are modulated by reinforcement signals. Simulations based on the model are shown to produce various types of neural activity similar to those found in experiments.