The "Quiet Eye" and Motor Performance: Task Demands Matter!

Evidence suggests that superior motor performance coincides with a longer duration of the last fixation before movement initiation, an observation called “quiet eye” (QE). Although the empirical findings over the last two decades underline the robustness of the phenomenon, little is known about its functional role in motor performance. Therefore, a novel paradigm is introduced, testing QE duration as an independent variable by experimentally manipulating the onset of the last fixation before movement unfolding. Furthermore, this paradigm is employed to investigate the functional mechanisms behind the QE phenomenon by manipulating the predictability of the target position and thereby the amount of information to be processed over the QE period. The results further support the assumption that QE affects motor performance, with experimentally prolonged QE durations increasing accuracy in a throwing task. However, it is only under a high information-processing load that a longer QE duration is beneficial for throwing performance. Therefore, the optimization of information processing, particularly in motor execution, turns out to be a promising candidate for explaining QE benefits on a functional level.

The Quiet Eye and motor performance – Introducing fixation duration as an independent variable

Evidence suggests a strong relation between superior motor performance and the duration of the last fixation before movement initiation (called Quiet Eye, QE). Although this phenomenon proves to be quite robust, to date, only little is known about its functional role. Therefore, in two experiments, a novel paradigm is introduced, testing the QE as independent variable by experimentally manipulating the duration of the last fixation in a throwing task. In addition, this paradigm allowed for the manipulation of the predictability of the target position. Results of the first study revealed an increase in throwing accuracy as function of experimentally prolonged QE durations. Thus, the assumption that the QE does not surface as a mere by-product of superior performance could be confirmed. In the second study, this dependency was found only under high task-demand conditions in which the target position was not predictable. This finding confirms the hypothesis that it is the optimization of information processing which serves as the crucial mechanisms behind QE effects.

Assessment of post-stroke fatigue: the fatigue scale for motor and cognitive functions

Post-stroke fatigue (PSF) is an important but still controversial issue since knowledge on its nature is still humble. The aim of the present study was to characterize PSF beyond the subacute phase.

Adenosine A2A receptor gene expression in the normal striatum and after 6-OH-dopamine lesion

Adenosine A2A receptors are present on enkephalinergic medium sized striatal neurons in the rat and have an important function in the modulation of striatal output. In order to establish more accurately whether adenosine transmission is a generalized phenomenon in mammalian striatum we compared the A2A R expression in the mouse, rat, cat and human striatum. Secondly we compared the modulation of enkephalin gene expression and A2A receptor gene expression in rat striatal neurons after 6-OH-dopamine lesion of the substantia nigra. Hybridization histochemistry was performed with a 35S-labelled radioactive oligonucleotide probe. The results showed high expression of A2A adenosine receptor genes only in the medium-sized cells of the striatum in all examined species. In the rat striatum, expression of A2A receptors was not significantly altered after lesion of the dopaminergic pathways with 6-OH-dopamine even though enkephalin gene expression was up-regulated. The absence of a change in A2A receptor gene expression after 6-OH-dopamine treatment speaks against a dependency on dopaminergic innervation. The maintained inhibitory function of A2A R on motor activity in spite of dopamine depletion could be partly responsible for the depression of locomotor activity observed in basal ganglia disorders such as Parkinson's disease.

Principals, agents, and the European Union’s foreign economic policies

In the introduction to this collection on the principal–agent approach and the European Union’s (EU) foreign economic policies we briefly present the EU’s institutional structure for policy-making in trade, monetary, development and international competition and financial policy. We also offer some data on the extent of the EU’s involvement in the international economy. Our discussion of the principal–agent approach and how it can be applied to an analysis of the EU’s foreign economic policies forms the basis of the following contributions. It allows us to formulate three questions that are of particular interest for applications of the principal–agent approach to the EU. Finally, we summarize the various studies included in this collection.

The relation between cognitive and motor performance and their relevance for children’s transition to school: A latent variable approach

Both theoretically and empirically there is a continuous interest in understanding the specific relation between cognitive and motor development in childhood. In the present longitudinal study including three measurement points, this relation was targeted. At the beginning of the study, the participating children were 5-6-year-olds. By assessing participants' fine motor skills, their executive functioning, and their non-verbal intelligence, their cross-sectional and cross-lagged interrelations were examined. Additionally, performance in these three areas was used to predict early school achievement (in terms of mathematics, reading, and spelling) at the end of participants' first grade. Correlational analyses and structural equation modeling revealed that fine motor skills, non-verbal intelligence and executive functioning were significantly interrelated. Both fine motor skills and intelligence had significant links to later school achievement. However, when executive functioning was additionally included into the prediction of early academic achievement, fine motor skills and non-verbal intelligence were no longer significantly associated with later school performance suggesting that executive functioning plays an important role for the motor-cognitive performance link.