Learning and memory deficits upon TAU accumulation in Drosophila mushroom body neurons

Mutations in the neuronal-specific microtubule-binding protein TAU are associated with several dementias and neurodegenerative diseases. However, the effects of elevated TAU accumulation on behavioral plasticity are unknown. We report that directed expression of wild-type vertebrate and Drosophila TAU in adult mushroom body neurons, centers for olfactory learning and memory in Drosophila, strongly compromised associative olfactory learning and memory, but olfactory conditioning-relevant osmotactic and mechanosensory responses remained intact. In addition, TAU accumulation in mushroom body neurons did not result in detectable neurodegeneration or premature death. Therefore, TAU-mediated structural or functional perturbation of the microtubular cytoskeleton in mushroom body neurons is likely causal of the behavioral deficit. These results indicate that behavioral plasticity decrements may be the earliest detectable manifestations of tauopathies.     

Multiple time scales and subsystem embedding in the learning of juggling

To gain insight into the multiform dynamics and integration of remote yet pertinent subsystems into the performance of complex perceptual-motor skills, we recently conducted a series of longitudinal and cross-sectional experiments on the acquisition of 3-ball cascade juggling in which we measured, next to the ball trajectories, postural sway, eye and head movements and respiration. The aim of the present paper is to review the main results and theoretical implications of these experimental studies for understanding skill acquisition. As regards the evolution of the quality of the juggling itself, we found that only certain aspects of throwing and catching were adjusted, while the goal behavior of sustained juggling (operationalized as the number of consecutive throws) and the degree of frequency and phase locking between the ball trajectories, indexing pattern stability, increased monotonically. The latter three aspects evolved at different rates, reflecting the existence of a temporal hierarchy in learning. Postural sway exhibited initial manifestations of task-specific, possibly mechanically induced, modes of 3:1 and 3:2 frequency locking with the ball trajectories and only few transitions between those modes. Functional stability appeared to be enhanced during practice by minimizing the sway amplitudes rather than by adjusting the sway dynamics itself. Eye and point-of-gaze movements also showed instances of 3:1 and 3:2 frequency locking with the ball trajectories; especially establishing a 3:1 locking (horizontal eye movements) appeared to be important. Expert behavior suggested that extended practice promotes reliance on multiple sources of information, allowing the proficient juggler to switch adaptively between functional organizations involving distinct perceptual systems. No consistent coordination between breathing and juggling was found. It was concluded that multiform dynamics, involving hierarchically ordered time scales, underlie the acquisition of complex skills and that the subsystems subserving realization of the task goal become assembled and embedded in a task- and subsystem-specific manner.     

Personality disorders and personality dimensions in anorexia nervosa

Information on the relationship between anorexia nervosa (AN) and personality disorders (PDs) and dimensions of temperament and character (measured by the Temperament and Character Inventory [TCI; Cloninger, Przybeck Svrakic, & Wetzel, 1994]) is limited. This study examines the predictive validity of the TCI for PD diagnoses assessed by the International Personality Disorder Examination-ICD-10 (IPDE-ICD-10; Loranger, Janca, & Sartorius, 1997) interviews of 46 women with DSM-IV-defined AN. Patients with a PD reported higher levels of harm-avoidance and lower levels of self-directedness than those without a PD. Scores on the TCI were predictive of the number of PD features present, particularly for those PDs in the anankastic, anxious, and dependent groups accounting for 40% to 51% of the variance. Cluster analysis based on scores on the TCI identified a subgroup of patients characterized by low levels of novelty seeking, self-directedness, and cooperativeness and high levels of harm avoidance. This cluster included the majority of those with avoidant, anxious, or dependent PDs. Assessment of particular personality dimensions was able to predict PDs in an anorexic sample. Since normal personality dimensions have greater validity than the categorical PDs, a consideration of normal temperament and character may assist in clinical decisionmaking and considerations concerning treatment.     

Estimating the valence of single stimuli: a new variant of the Affective Simon Task

In this article, a modified variant of the Affective Simon Task (AST; De Houwer & Eelen, 1998) is presented as a measure of implicit evaluations of single stimuli. In the AST, the words "good" or "bad" have to be given as responses depending on the color of the stimuli. The AST was combined with an evaluation task to increase the salience of the valence of the presented stimuli. Experiment 1 investigated evaluations of schematic faces showing emotional expressions. In Experiment 2 we measured the valence of artificial stimuli that acquired valence in a game context during the experiment. Both experiments confirm the validity of the modified AST. The results also revealed a dissociation between explicit and implicit evaluations.     

Is there a Scandinavian psychology? A bibliometric note on the publication profiles of Denmark,Finland, Norway,and Sweden

This note presents a quantitative bibliometric analysis based on information obtained from the PsycINFO database concerning publication patterns in different subfields of Scandinavian psychology for the years 1984 to 1997. A cluster analysis shows that the publication profiles of the Scandinavian countries are more similar to each other than to both the profile of the USA and a norm profile based on all countries except the USA and Scandinavia. The main differences are that the relative proportions of articles dealing with psychological disorders are higher and the relative proportions of articles dealing with educational psychology are lower for Scandinavia than for the rest of the world. Within the Scandinavian countries, Finland and Sweden form one cluster with higher relative proportions of psychophysiological articles, and Denmark and Norway form one cluster with higher relative proportions of articles dealing with psychological disorders.     

Providing Foundations for Coherentism

We prove that four theses commonly associated with coherentism are incompatible with the representation of a belief state as a logically closed set of sentences. The result is applied to the conventional coherence interpretation of the AGM theory of belief revision, which appears not to be tenable. Our argument also counts against the coherentistic acceptability of a certain form of propositional holism. We argue that the problems arise as an effect of ignoring the distinction between derived and non-derived beliefs, and we suggest that the kind of coherence relevant to epistemic justification is the coherence of non-derived beliefs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Measuring the perceptual magnet effect in the perception of /i/ by German listeners

In a study of the internal category structure of the vowel /i/, Kuhl found a “perceptual magnet effect”: Discrimination sensitivity was poorer for category instances that were acoustically similar to the category prototype than it was for category instances that were not. The typicality of category exemplars was determined by goodness judgments and was found to correlate with the acoustics of average production. Analysis and interpretation of discrimination performance relied on two important assumptions: that listeners perceived all stimuli presented as exemplars of the same vowel category and that, apart from the influence of phonetic coding, discrimination sensitivity was the same across the investigated part of the vowel space. In the present study, it is shown that production and perception estimates of the category prototype may diverge, possibly because listeners seem to prefer hyperarticulated variants of vowel categories. An approach towards measurement of intra-category discrimination minima is put forward and tested that protects against intercategory confounds and avoids the isosensitivity assumption. Received: 26 November 1997 / Accepted: 25 May 1998     

A perception experiment with time-critical graphics animation on the World-Wide Web

The World-Wide Web offers a potentially interesting tool to collect data from a large and heterogeneous audience. While questionnaires have become rather common on the Internet, its potential reaches far beyond text processing. In principle, it is possible not only to perform interactive, dynamic experiments on the Web, but also to include graphical animation and time-critical responses, such as reaction times. We implemented a visual motion extrapolation task on the Web using the programming language Java, which can be interpreted by standard Web browsers such as Netscape or Internet Explorer. The data collected with this method turned out to be reliable and differed little from data obtained in a controlled laboratory setting, with the exception of conditions with fixation instruction. Thus, the Web can, generally speaking, be used for data collection of large sample sizes. The strengths and weaknesses of dynamic visual simulation experiments on the Internet are discussed.     

Somatovisceral interactions in visceral perception: Abdominal masking of colonic stimuli

Clinical and experimental evidence on referred pain and spinal-afferent convergence demonstrates a close relationship between visceral and somatosensory perception, which is important for current models of symptom perception and central body representation. The study uses a psychophysical approach to quantify these interactions at the perceptual level, taking into account problems of comparable intermodal scaling and the role of awareness. An experiment on somatosensory masking of distension stimuli in the colon is reported in which a multiple staircase method of forced choice discrimination with concurrent sensation ratings was employed. Results showed perceptual masking of visceral by abdominal stimuli but not vice versa. The masking effect was not enhanced by intratomal placement of the abdominal stimulus in the lower left quadrant. This contradicts the spinal sensory convergence model and points to perceptual interactions at higher brain levels. Loglinear analysis of relations between discrimination and subjective sensation revealed qualitative differences of somatovisceral perception at the preconscious as compared to the conscious level. This argues for a two-process model of integrative body perception.     

Islamic scholar and religious leader: A portrait of Shaykh Muhammad Sa'id Ramadan al‐Būti

In the light of his outstanding reputation and great influence on life in modern Syria, it is amazing that Shaykh Muhammad Sa'id Ramadan al‐Būti's work and thought are under‐represented to the extent of being almost unknown in European academic literature. This article is a first attempt at a broader European appraisal of al‐Būti's life and work. It paints a portrait of a thinker who represents the majority of Sunni Islam or the ‘middle path Islam’ in Syria, finding its place between the current realities of a secular state and an ideal Islamic society. The article first introduces the biographical details of al‐Būti's life and the main intellectual influences of people and events around him, then his ?uvre, style and personality. Secondly, it explores his main ideas and views, taking into account the fact that he writes and speaks in two different roles: as an Islamic scholar and as a religious leader, which is perhaps a unique position in modem Syria.