Egocentric

The aim of this study is to investigate the difference of EEG dynamics on navigation performance. A tunnel task was designed to classify subjects into allocentric or egocentric spatial representation users. Despite of the differences of mental spatial representation, behavioral performance in general were compatible between the two strategies subjects in the tunnel task. Task-related EEG dynamics in power changes

Rats use place (allocentric) or stimulus–response (egocentric) learning strategies for foraging under ethological and/or experimental conditions, proposed to be conveyed by hippocampus or neostriatum, respectively. We investigated here the effect of a reversible blockade of neostriatum on learning strategies assessed by a cross maze paradigm, comparing A × C (phenotypically similar to wild rats) versus Long–Evans rat strains. The rats were trained to reach a consistently baited-arm (west arm), starting from the same arm (south arm). The learning strategy was evaluated at days 11 and 19, when test trials were performed placing the rat in a start-box at the arm (north arm) opposite to that when starting the training, following a saline or lidocaine injection into the neostriatum. Rats entering to the baited-west arm were considered to be place learners and those entering to the unbaited-east arm were response learners. It was found that Long–Evans rats injected with saline were place learners on day 11 and response learners on day 19, but were place learners on both days when injected with lidocaine. A × C rats injected with saline were response learners on days 11 and 19, and place learners on both days when injected with lidocaine. Thus, rat strain influences the memory strategy for solving a cross maze paradigm. Long–Evans, but not A × C rats, shift from place (allocentric) to response (egocentric) learning along the training. When neostriatum was blocked by lidocaine, both rat strains elicited a place learning strategy only.

The article attempted to analyse critically the definition of trauma as it is used in the Western medical and psychiatry contexts in order to come up with an appropriate African definition. This was undertaken with the view to demonstrate that the Western worldview is different from the African worldview. Superimposing solutions or providing pre-packed answers to unique African problems will lead only to re-traumatisation, whereas cultural sensitivity and the right diagnosis will lead to the correct treatment. The driving force behind this article was therefore to aim to be relevant, effective and contextual in all African-based pastoral care.

Recent research development on egocentric social network analysis focuses on the causes and consequences of relationships among sets of people rather than on the features, attribute data of individuals, and their basic database operations. This work describes a record type of network data model that would be suitable to perform database operations in social network analysis (SNA). It describes two schemas that would be needed for web space interface and database op-erations. A force directed algorithm was used to display membership vertices that show link membership number, name, and pictures. A Breadth first search algorithm was then embedded in the algorithm to avoid endless searching in cycled nodes. Measurement of degree of centrality, betweenness, and closeness was incorporated to determine the relationship among the nodes and their linkages. Implementation of database operations into SNA reveals not only social informa-tion but also critical economic reports of the individuals...

In the last decade many studies examined egocentric and allocentric spatial relations. For various tasks, navigators profit from both kinds of relations. However, their interrelation seems to be underspecified. We present four elementary representations of allocentric and egocentric relations (sensorimotor contingencies, egocentric coordinate systems, allocentric coordinate systems, and perspective-free representations) and discuss them with respect to their encoding and retrieval. Elementary representations are problematic for capturing large spaces and situations which encompass both allocentric and egocentric relations at the same time. Complex spatial representations provide a solution to this problem. They combine elementary coordinate representations either by pair-wise connections or by hierarchical embedding. We discuss complex spatial representations with respect to computational requirements and their plausibility regarding behavioral and neural findings. This work is mean...

The ability to orient in space constitutes a main sign of cognitive impairment in Alzheimer’s disease (AD). Presently, a peculiar aspect of topographical disorientation in AD linked with spatial reference frame congruence appears to have been only minimally investigated. We aim to study whether there is a decline in performing the allo- to egocentric translation of spatial knowledge during different types of wayfinding in AD patients. We introduced two virtual reality tasks, the VR-Maze and VR-Road Map tasks, in which we compared 26 AD and 26 healthy, elderly subjects. The results emphasize that there is a specific reduction in performing allo- to egocentric spatial tasks in AD, whereas this reduction is not as evident in equivalent allocentric spatial tasks. The data are consistent with the neurological results regarding the early degeneration of the hippocampus and retrosplenial cortex in AD, which underlies the ability to translate between these two reference frames.