Cortex, countercurrent context, and dimensional integration of lifetime memory

The correlation between relative neocortex size and longevity in mammals encourages a search for a cortical function specifically related to the life-span. A candidate in the domain of permanent and cumulative memory storage is proposed and explored in relation to basic aspects of cortical organization. The pattern of cortico-cortical connectivity between functionally specialized areas and the laminar organization of that connectivity converges on a globally coherent representational space in which contextual embedding of information emerges as an obligatory feature of cortical function. This brings a powerful mode of inductive knowledge within reach of mammalian adaptations, a mode which combines item specificity with classificatory generality. Its neural implementation is proposed to depend on an obligatory interaction between the oppositely directed feedforward and feedback currents of cortical activity, in countercurrent fashion. Direct interaction of the two streams along their cortex-wide local interface supports a scheme of "contextual capture" for information storage responsible for the lifelong cumulative growth of a uniquely cortical form of memory termed "personal history." This approach to cortical function helps elucidate key features of cortical organization as well as cognitive aspects of mammalian life history strategies

The quantitative analysis of neurodegenerative disease:Classification, noda, constellations, and multivariate geometry

A  variety of methods are available for the quantitative description and analysis of neurodegenerative disease. If neurodegenerative disease exists as a series of distinct disorders, then classificatory methods such as hierarchical cluster analysis (HCA) and decision tree analysis (DTA) can be used to classify cases into groups more objectively. If neurodegenerative disease consists of overlapping phenotypes, then the Braun-Blanquet ‘nodal’ system and ‘constellation diagrams’ implicitly recognise intermediate cases and reveal their relationships to the main groupings. By contrast, if cases are more continuously distributed without easily distinguishable disease entities, then methods based on spatial geometry, such as a triangular system or principal components analysis (PCA), may be more appropriate as they display cases spatially according to their similarities and differences. This review compares the different methods and concludes that as a result of the heterogeneity and overlap commonly present plus the multiplicity of possible descriptive variables, methods such as PCA are likely to be particularly useful in the quantitative analysis of neurodegenerative disease. A more general application of such methods, however, has implications for studies of disease risk factors and pathogenesis and in clinical trials

An Analysis of Learning Bahaviour and Patterns in a Technology-Enhanced Learning Environment

Characterizing, structuring and supplying necessary knowledge for solving complex problems in today’s dynamically changing environments is a great challenge. This paper provides an introductory description of the STUDIO learning environment that supports learners in applying and evaluating knowledge and in adapting changes to their own context quickly. The focus of the current study is on analysing learning characteristics and behaviours of undergraduate students of a Management Information System course, who used the STUDIO to facilitate the acquisition of required knowledge. A detailed description of data analysis and the interpretation of results applying cognitive frameworks will be provided

Conceptual Patchworks and Conceptual Housekeeping

Recent work on scientific concepts has established that they often have a patchwork structure, in which use is regimented into distinct patches of application associated with distinct size- and/or time-scales, measurement techniques, and licensed inferences. Patchworks thus inherently involve structured polysemy. Why tolerate such conceptual complexity? Why not use distinct terms for each patch to avoid the threat of equivocation? At the very least, an account is owed about when such complexity goes too far: how and when do patchwork concepts fail? We address these questions by considering two cases of conceptual housekeeping: cases where the relevant scientists themselves judged a patchwork concept to have gone too far and took steps to clean up the mess. On the basis of these case studies (plus supporting normative arguments), we defend two theses. We argue, first, that such housekeeping efforts are context-sensitive: concept deviance cannot be read off concept structure alone. Second, we defend minimalism about such housekeeping: tolerance for conceptual complexity is an appropriate default attitude

Genetic influences on gyrification of the cerebral cortex in schizophrenia: a twin study

Veränderungen in der kortikalen Gyrifizierung, d.h. in der Formation der Windungen und Furchen im Gehirn, wurden bei Patienten mit Schizophrenie wiederholt berichtet. In der vorliegenden Arbeit wurde der Parameter der Absoluten Mittleren Kurvatur (engl. „Absolute Mean Curvature“, AMC) herangezogen, um den regionalen kortikalen Gyrifizierungsindex (GI) zu quantifizieren. In einer ersten Studie konnte hierbei festgestellt werden, dass diese Methode zur Untersuchung der Gyrifizierung die kombinierte Auswertung von Magnetresonanztomographie (MRT) Daten unterschiedlicher Untersuchungszentren erlaubt. Hierfür wurden strukturelle MRT Messungen an (a) einem gesunden Probanden, der insgesamt 12 mal in MRT Scannern zweier unterschiedlicher Untersuchungszentren und (b) sechs gesunden Probanden, die in vier MRT Scannern unterschiedlicher Untersuchungszentren gemessen wurden, durchgeführt. Im Anschluss wurde die kortikale Oberfläche jeder Hemisphäre sowie die Absolute Mittlere Kurvatur für jeden Vertex im Gehirn berechnet. Die Koeffizienten der Intra-Klassen-Korrelation (engl. ”intra-class correlation”, ICC) erwiesen sich sowohl für die Daten desselben Probanden als auch die Daten der verschiedenen Untersuchungszentren als hoch. In einer zweiten Studie wurden sodann strukturelle MRT Daten von 104 monozygoten Zwillingen, d.h. 27 monozygoten gesunden Zwillingspaaren und 25 monozygoten, im Hinblick auf Schizophrenie diskordanten Zwillingspaaren aus drei verschiedenen Untersuchungszentren kombiniert. Hier ergaben sich höhere Korrelationen in der Gyrifizierung innerhalb der diskordanten Zwillingspaare im Vergleich zu gesunden Zwillingpaaren. Dieser Befund deutet darauf hin, dass monozygote Zwillinge mit einer Diskordanz für die Erkrankung diesbezüglich eine größere Ähnlichkeit aufweisen und eine genetische Veranlagung zur schizophrenen Erkrankung möglicherweise eine relevante Rolle im Rahmen der Gyrifizierung spielen könnte. Zudem ließ sich eine erhöhte linksseitige Gyrifizierung im Bereich des frontopolaren Kortex sowie in mittleren temporalen, parahippokampalen und fusiformen Arealen sowohl bei erkrankten als auch nicht affizierten Co-Zwillingen im Vergleich zu den gesunden Zwillingen feststellen

A Scale-Free, Relational Approach to Social Development in Late-Prehistoric Tyrrhenian Central Italy.

This dissertation examines the interplay between relational patterns and trajectories of social development within late-prehistoric Tyrrhenian Central Italy (TCI). Despite historical disagreement, TCI is now recognized as a context of radical social transformations leading to or even encompassing the formation of states and cities. Between the end of the Bronze Age and the Early Iron Age (12th-8th centuries BCE), in concert with substantial changes attested in the funerary record, hundreds of small settlements distributed evenly across the research area were replaced by a few large and formally heterogeneous centers. Based on a narrow evidentiary range, these developments tend to be viewed in terms of differential progression along a single axis of complexity, with the emerging centers categorized according to apparent scale and historical prominence. The aim of this work is not to establish TCI as a case of state formation and urbanization according to one or another definition. Following anthropological perspectives that emphasize the importance of parsing the dynamics underlying qualitative changes in the form of social collectives, I focus on tracing developmental trajectories within a systematically validated relational plane as a first step toward identifying better bases for comparison, categorization, and ultimately explanation. In practice, I derive large datasets for network reconstruction from the TCI mortuary record and apply tools developed for the study of complex networks to track the position of social collectives over time and extract summary measures of relational distance. I use these measures to evaluate three aspects of the transformations attested between the end of the Bronze Age and the Early Iron Age: 1) the degree of local and regional coordination involved in the shift from a large number of small villages to relatively few large centers; 2) the impact of shifting axes of long-distance exchange on local relational patterns; and 3) the relationship between the formal characteristics and internal substance of the new settlements. I conclude that the watershed changes attested across the research area can be understood in reference to uniform endogenous processes leading to the emergence of comparable social collectives.PhDIndependent Interdepartmental Degree ProgramUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133403/1/cangemi_1.pd