Do differences in brain activation challenge universal theories of dyslexia?

It has been commonly agreed that developmental dyslexia in different languages has a common biological origin: a dysfunction of left posterior temporal brain regions dealing with phonological processes. Siok, Perfetti, Jin, and Tan (2004, Nature, 431, 71-76) challenge this biological unity theory of dyslexia: Chinese dyslexics show no deficits in posterior temporal brain regions but a functional disruption of the left middle frontal gyrus. Here, I will argue that these data do not challenge universal cognitive theories of dyslexia according to which weaknesses in the ability to process the phonological features of language are at the origin of dyslexia.     

Neuroendocrine responses to psychological stress in eumenorrheic and oligomenorrheic women

Neuroendocrine adaptive responses to psychological stress include activation of the hypothalamic-pituitary-adrenal (HPA) axis and sometimes suppression of the hypothalamic-pituitary-gonadal (HPG) axis. In women who experience chronic stress, these responses are probably responsible for disturbances in the menstrual cycle. In the present experiment, we investigated the effect of an acutely stressful situation on the physiological and neuroendocrine responses in college age women. We hypothesized that females who are experiencing some degree of abnormal menstrual function or women who have less-robust cycles (oligomenorrheic females) would exhibit differences in gonadotropin secretion from eumenorrheic females when exposed to psychological stressors. Fifteen women completed this study: eumenorrheic (n = 5) and oligomenorrheic women (n = 5) who experienced a series of psychological stressors, and eumenorrheic controls (n = 5). Blood samples were taken at 10 min intervals for 8 h (09:00-17:00) in each woman during the mid-follicular phase of the menstrual cycle. The psychological stressors were administered for 1 h beginning at 13:00 h. Luteinizing hormone (LH), growth hormone (GH) and cortisol were measured in each sample to assess the effect of stress on secretion of these hormones. Deconvolution analysis was used to analyze pulsatile hormone secretion and the approximate entropy (ApEn) statistic analyzed the regularity of release of each hormone. Although, there were significant changes in heart rate (HR), skin resistance (SR) and cortisol levels in the stressed women during the psychological stressor compared to resting baseline values but not in the controls, there was no difference in either LH or GH secretion between women who experienced stress and those who did not. Furthermore, there were no differences in the LH or GH secretion patterns in the oligomenorrheic and eumenorrheic women exposed to the psychological stressor.     

Protein synthesis-dependent long-term memory induced by one single associative training trial in the parasitic wasp Lariophagus distinguendus

Protein synthesis-dependent long-term memory in Apis mellifera and Drosophila melanogaster is formed after multiple trainings that are spaced in time. The parasitic wasp Lariophagus distinguendus remarkably differs from these species. It significantly responds to the artificial odor furfurylheptanoate (FFH) in olfactometer experiments, when this odor was presented during one single training trial, consisting of one sequence of host recognition behavior on a wheat grain infested by its hosts. Feeding wasps with actinomycin D erases the learned response 24 h after the training, demonstrating that protein synthesis-dependent long-term memory has been formed in L. distinguendus already after one single training.     

Becoming literate in different languages: similar problems, different solutions

The teaching of reading in different languages should be informed by an effective evidence base. Although most children will eventually become competent, indeed skilled, readers of their languages, the pre-reading (e.g. phonological awareness) and language skills that they bring to school may differ in systematic ways for different language environments. A thorough understanding of potential differences is required if literacy teaching is to be optimized in different languages. Here we propose a theoretical framework based on a psycholinguistic grain size approach to guide the collection of evidence in different countries. We argue that the development of reading depends on children's phonological awareness in all languages studied to date. However, we propose that because languages vary in the consistency with which phonology is represented in orthography, there are developmental differences in the grain size of lexical representations, and accompanying differences in developmental reading strategies across orthographies.     

Differential relational encoding of categorical information in memory for action events

Memory for action phrases is better if the actions are enacted in subject-performed tasks (SPTs) than if they are only listened to in verbal tasks (VTs). This effect is ascribed to better item-specific encoding of SPTs than of VTs. The role of interitem relational information is controversial, and the findings of clustering with categorically structured lists are inconsistent (see Engelkamp, 1998). The present study contributes to clarifying these effects by demonstrating that intentional relational encoding can be used more efficiently in VTs than in SPTs and influences the degree of clustering. If the list structure is not obvious, inducing intentional encoding by presenting the category labels prior to list presentation and asking subjects to use this preinformation increases clustering in VTs but not in SPTs. Without preinformation, clustering scores of VTs and SPTs did not differ, with preinformation, clustering of VTs was stronger than that of SPTs. The authors suggest how the inconsistent findings with regard to clustering effects can be explained.     

Reading acquisition, developmental dyslexia, and skilled reading across languages: a psycholinguistic grain size theory

The development of reading depends on phonological awareness across all languages so far studied. Languages vary in the consistency with which phonology is represented in orthography. This results in developmental differences in the grain size of lexical representations and accompanying differences in developmental reading strategies and the manifestation of dyslexia across orthographies. Differences in lexical representations and reading across languages leave developmental "footprints" in the adult lexicon. The lexical organization and processing strategies that are characteristic of skilled reading in different orthographies are affected by different developmental constraints in different writing systems. The authors develop a novel theoretical framework to explain these cross-language data, which they label a psycholinguistic grain size theory of reading and its development.     

Do patients with OCD and pathological gambling have similar dysfunctional cognitions?

The obsessive-compulsive spectrum disorder (OCSD) theory postulates that a wide range of disorders is closely related to OCD. Current cognitive models ascertain that certain beliefs leading to misinterpretation of the significance of intrusions are important in the etiology and maintenance of OCD. This study examined whether pathological gambling, a disorder belonging to the OC spectrum, is characterized by similar dysfunctional cognitions as OCD. Dysfunctional beliefs of OCD patients were compared to those of patients with pathological gambling, panic disorder and normal controls. These beliefs were measured by the Obsessive-compulsive Beliefs Questionnaire-87 (OBQ-87), which was developed by a group of leading OCD researchers [Behav. Res. Ther. 35 (1997) 667]. It was hypothesized that according to the OCSD theory, pathological gamblers would exhibit similar cognitions to OCD patients, as well as increased levels of OCD symptoms. Analysis showed that OCD patients exhibited higher OBQ-87 scores than both panic patients and normal controls, but equal to pathological gambling patients. Pathological gamblers exhibited, however, no increase in OCD symptoms. These mixed results do not seem to support the OC spectrum theory for pathological gambling, moreover being contradictory to contemporary cognitive OCD models.     

Design-effects in prospective and retrospective memory for actions

There is ample evidence that memory for action phrases such as "open the bottle" is better in subject-performed tasks (SPTs), i.e., if the participants perform the actions, than in verbal tasks (VTs), if they only read the phrases or listen to them. It is less clear whether also the sole intention to perform the actions later, i.e., a prospective memory task (PT), improves memory compared with VTs. Inconsistent findings have been reported for within-subjects and between-subjects designs. The present study attempts to clarify the situation. In three experiments, better recall for SPTs than for PTs and for PTs than for VTs were observed if mixed lists were used. If pure lists were used, there was a PT effect but no SPT over PT advantage. The findings were discussed from the perspective of item-specific and relational information.     

Categorical-relational and order-relational information in memory for subject-performed and experimenter-performed actions

Memory for self-performed tasks (SPTs) is better than memory for experimenter-performed tasks (EPTs). In short unrelated lists of actions this effect occurs if the encoding condition is manipulated within subjects. In a between-subjects design, the enactment effect disappears (J. Engelkamp & D. Dehn, 2000; J. Engelkamp & H. D. Zimmer, 1997). These findings were explained by the item-order hypothesis, which claims that encoding order information depends on the type of encoding and design. The authors demonstrate that this differential encoding of order information in EPTs and SPTs is not effective in free recall if categorized lists are used. The use of categorized lists makes the interaction of type of encoding and design in free recall of short lists disappear, and the enactment effect reappears independent of the type of design.     

The item-order hypothesis reconsidered: The role of order information in free recall

According to the item-order approach of free recall, in pure short lists the free recall of unrelated items is organized according to their order of presentation in the study list. The approach was applied in the present study to experimenter-performed tasks (EPTs) and subject-performed tasks (SPTs). It claims that EPTs provide better serial order information than SPTs. Consequently, free recall of EPTs should be more organized along the presentation order of the items than the free recall of SPTs. In three experiments, some specific aspects of this approach were studied. Firstly, it was demonstrated that serial retrieval is not strongly used spontaneously and that its use is overestimated in the literature because it is usually evoked by an order reconstruction test which follows free recall testing. Secondly, a serial retrieval strategy in free recall can be encouraged by explicit instructions. Finally, the present experiments showed that a serial output strategy alone does not allow one to predict performance in free recall. The implications of these findings for the item-order approach will be discussed.