Book review: the Jordanian labour market in the new millennium edited by Ragui Assaad

This collection aims to cover topics that are essential to understanding the conditions leading to the Arab Spring, including the persistence of high youth unemployment despite healthy economic growth, the co-existence of migration and unemployment, and the unusually early retirement among prime-age workers. For anyone conducting research on Jordan, this book provides careful analyses of the most recent data on the Jordanian labour market and its underlying patterns, writes Henrike M. Hirnstein

Evolutionary advantages of human hemispheric asymmetries

Hemispheric asymmetries are a basic principle of human brain organization. Once thought to be unique to humans, hemispheric asymmetries have meanwhile been documented in a wide range of species, suggesting they contain an evolutionary advantage. However, there are a few theories as to why asymmetry confers such an advantage and, moreover, there is a paucity of empirical work which is chiefly limited to a small number of animal studies. The present thesis is concerned with directly testing theories about potential evolutionary advantages in humans. Because it is widely believed that hemispheric asymmetries generally enhance cognitive processing, the first study Investigated the general relationship between functional lateralization and cognitive performance using two visual half-field paradigms. The second study employed the same paradigms to test the notion that hemispheric asymmetries specifically enhance parallel processing. The final study tested the notion that high degrees of lateralization (determined with a dichotic listening test) are associated with enhanced left-right discrimination. It was hypothesized that in all studies highly lateralized participants would outperform less lateralized participants. In contrast to our hypotheses however, highly lateralized participants were consistently outperformed by less lateralized participants. Less lateralized participants showed higher cognitive performance and excelled at parallel processing and left-right discrimination. The results of the present thesis thus challenge a) the general notion that high degrees of lateralization are associated with enhanced cognitive processing, b) the specific notions that lateralization enhances parallel processing and left-right discrimination and c) the idea that hemispheric asymmetries are advantageous for cognitive processing per se. Taken together with previous studies, it is argued that advantages of hemispheric asymmetries depend on the degree of lateralization and situational requirements. That is, high, low and intermediate degrees of lateralization of the brain are each associated with distinct advantages (and disadvantages), depending on the demands placed upon it

How brain asymmetry relates to performance – a large scale dichotic listening study

All major mental functions including language, spatial and emotional processing are lateralized but how strongly and to which hemisphere is subject to inter- and intraindividual variation. Relatively little, however, is known about how the degree and direction of lateralization affect how well the functions are carried out, i.e., how lateralization and task performance are related. The present study therefore examined the relationship between lateralization and performance in a dichotic listening task for which we had data available from 1839 participants. In this task, consonant-vowel syllables are presented simultaneously to the left and right ear, such that each ear receives a different syllable. When asked which of the two they heard best, participants typically report more syllables from the right ear, which is a marker of left-hemispheric speech dominance. We calculated the degree of lateralization (based on the difference between correct left and right ear reports) and correlated it with overall response accuracy (left plus right ear reports). In addition, we used reference models to control for statistical interdependency between left and right ear reports. The results revealed a u-shaped relationship between degree of lateralization and overall accuracy: the stronger the left or right ear advantage, the better the overall accuracy. This u-shaped asymmetry-performance relationship consistently emerged in males, females, right-/non-right-handers, and different age groups. Taken together, the present study demonstrates that performance on lateralized language functions depends on how strongly these functions are lateralized. The present study further stresses the importance of controlling for statistical interdependency when examining asymmetry-performance relationships in general

Transcranial direct current stimulation (tDCS) enhances internal source monitoring abilities in healthy participants

Source monitoring refers to the ability to identify the origin of a memory, for example, whether you remember saying something or thinking about it, and confusions of these sources have been associated with the experience of auditory verbal hallucinations (AVHs). Both AVHs and source confusions are reported to originate from dysfunctional brain activations in the prefrontal cortex (PFC) and the superior temporal gyrus (STG); specifically, it is assumed that a hypoactive PFC and a hyperactive STG gives rise to AVHs and source confusions. We set out to test this assumption by trying to mimic this hypertemporal/hypofrontal model in healthy individuals with transcranial direct current stimulation (tDCS): the inhibitory cathode was placed over the left PFC and the excitatory anode over the left dorsolateral STG. Participants completed a reality monitoring task (distinguishing between external and internal memory sources) and an internal source monitoring task (distinguishing between two or more internal memory sources) in two separate experiments (offline vs. online tDCS). In the offline experiment (n = 34), both source monitoring tasks were completed after tDCS stimulation, and in the online experiment (n = 27) source monitoring tasks were completed while simultaneously being stimulated with tDCS. We found that internal source monitoring abilities were significantly enhanced during active online tDCS, while reality monitoring abilities were unaffected by stimulation in both experiments. We speculate, based on combining the present findings with previous studies, that there might be different brain areas involved in reality and internal source monitoring. While internal source monitoring seems to involve speech production areas, specifically Broca’s area, as suggested in the present study, reality monitoring seems to rely more on the STG and DLPFC, as shown in other studies of the field.publishedVersio

A multimodal study of the effects of tDCS on dorsolateral prefrontal and temporo-parietal areas during dichotic listening

The underlying neural mechanisms of transcranial direct current stimulation (tDCS), especially beyond the primary motor cortex, remain unclear. Several studies examined tDCS effects on either functional activity, neurotransmitters or behavior but few investigated those aspects together to reveal how the brain responds to tDCS. The objective is to elucidate the underlying mechanisms of tDCS using a multimodal approach that extends from behavioral to neurotransmitter levels of explanation. Thirty‐two healthy participants performed an auditory dichotic listening task at two visits, one session with sham and one session with real tDCS (2 mA) while simultaneously undergoing functional magnetic resonance imaging (fMRI). The anode and cathode were placed over the left temporo‐parietal cortex (TPC) and dorsolateral prefrontal cortex, respectively. Before and after simultaneous dichotic listening/fMRI/tDCS, combined glutamate and glutamine (Glx) and myo‐inositol levels were assessed in the stimulated areas. While fMRI and dichotic listening showed expected functional activity and behavioral effects, neither method demonstrated differences between real and sham stimulation. Glx only showed a statistical trend towards higher levels after real tDCS in both stimulated brain areas. There were no significant correlations between behavior and Glx. Despite a reasonable sample size, electrical field strength, and replication of behavioral and functional activity results, tDCS had little to no effect on dichotic listening, Glx, and functional activity. The study emphasizes that findings about the underlying neural mechanisms of the primary motor cortex cannot simply be generalized to other brain areas. Particularly, the TPC might be less sensitive to tDCS. Moreover, the study demonstrates the general feasibility of multimodal approaches

Positive Youth Development and Depression: An Examination of Gender Differences in Croatia and Spain

Depression is a major public health issue and the literature has consistently showed that the rates of depression increase dramatically during youth transition to adulthood, and gender differences merge in this period. Positive youth development (PYD) framework is focused on strengths that make young people more resistant to negative outcomes, like depression, and more capable to choose a positive life direction. The aim of the study was to examine the relationship between the 5Cs of PYD and depression in Croatia and Spain, as well as to analyze gender differences. This research was conducted within the PYD Cross-National Project. High school and university students from Eastern Croatia and Southern Spain participated in the study (Mage = 19.37, SD = 2.11; 62.3% female). There were 584 students from Croatia and 768 students from Spain, who filled in self-reports of PYD and depression (i.e., PYD-SF and PHQ-9, respectively). Results showed that male participants presented more Competence and Confidence, while female participants reported more Connection, Caring, Character, overall PYD, but also more depressive symptoms. Furthermore, Confidence and Connection were negative correlates of depressive symptoms, with neither Spain nor Croatia showing remarkable gender differences. These results may have some implications concerning the promotion of the 5Cs of PYD as a recommendable approach to promote youth mental health in Croatia and Spain from a gender perspective. Youth mental health services and initiatives that engage the partnership of youth contexts, such as the family, schools and neighborhoods, should not only address risk factors for mental health problems, but also protecting factors as the 5Cs, thus providing a more inclusive and sustainable support for youth well-being.publishedVersio

Pilot-RCT Finds No Evidence for Modulation of Neuronal Networks of Auditory Hallucinations by Transcranial Direct Current Stimulation

Background: Transcranial direct current stimulation (tDCS) is used as treatment for auditory verbal hallucinations (AVH). The theory behind the treatment is that tDCS increases activity in prefrontal cognitive control areas, which are assumed to be hypoactive, and simultaneously decreases activity in temporal speech perception areas, which are assumed to be hyperactive during AVH. We tested this hypofrontal/hypertemporal reversal theory by investigating anatomical, neurotransmitter, brain activity, and network connectivity changes over the course of tDCS treatment. Methods: A double-blind, randomized controlled trial was conducted with 21 patients receiving either sham or real tDCS treatment (2 mA) twice daily for 5 days. The anode was placed over the left dorsolateral prefrontal cortex (DLPFC) and the cathode over the left temporo-parietal cortex (TPC). Multimodal neuroimaging as well as clinical and neurocognitive functioning assessment were performed before, immediately after, and three months after treatment. Results: We found a small reduction in AVH severity in the real tDCS group, but no corresponding neuroimaging changes in either DLPFCD or TPC. Limitations: The study has a small sample size. Conclusion: The results suggest that the currently leading theory behind tDCS treatment of AVH may need to be revised, if confirmed by studies with larger N. Tentative findings point to the involvement of Broca’s area as a critical structure for tDCS treatment.publishedVersio