Working memory (WM) deficits are a core feature of schizophrenia. However, it has not been examined whether these deficits are related to altered temporal dynamics of information acquisition and changes in executive cognitive control. Therefore, the present study intended to quantify and model the dynamic process of information acquisition during continuous overlearning of WM information. It also aimed at investigating the relation between overlearning-associated change in behavioral performance and brain activity. Thirteen schizophrenic patients and 13 healthy volunteers were studied with functional magnetic resonance imaging (fMRI) while performing a recently developed overlearning paradigm [Koch K, Wagner G, von Consbruch K, Nenadic I, Schultz C, Ehle C, Reichenbach J, Sauer H, Schlösser R (2006) Temporal changes in neural activation during practice of information retrieval from short-term memory: An fMRI study. Brain Res 1107:140–150]. Consistent with the earlier study, short-term learning of stimulus material was associated with significant performance improvements and exponential signal decreases in a fronto-parieto-cerebellar network both in schizophrenic patients and in healthy volunteers. Against expectation patients exhibited stronger signal decreases relative to controls in anterior cingulate (Brodmann area (BA) 32), middle and superior temporal (BA 37, BA 22), superior frontal (BA 8/9, BA 6) and posterior parietal regions (BA 40). Furthermore, the individually modeled exponential decay rate of the blood oxygenation level-dependent signal in the right dorsolateral prefrontal cortex was significantly correlated with exponential decrease in mean behavioral response times in healthy controls while a statistical trend emerged in patients. A relative hyperactivation in the patient group was observable only at the start of the learning process and diminished with continued overlearning. This effect might indicate a gradual reduction of recruited neuronal resources and a practice-associated activation normalization in patients with schizophrenia. Our data suggest that in subacute patients learning and associated decreases in cerebral activation brought about by short-term practice are left unimpaired.

Transparent Nd:YAG ceramic was fabricated by the solid-state reaction method with an additional round of pre-calcining using nanopowders of 1 at.% Nd:Y2O3 and Al2O3 synthesized by laser ablation. The pre-calcining step and addition of tetraethyl orthosilicate was found crucial for fabricating high optical quality Nd:YAG ceramic from such nanoparticles. The transmittance of the obtained 2-mm-thick Nd:YAG ceramic was 83.6% at the wavelength of 1064 nm, which is very close to the theoretical value. The uniformity of the optical quality of ceramic was mapped by analyzing the point-by-point transmission of a focused laser beam. The average volume of the scattering centers in the obtained ceramic was evaluated by direct count method to be 17 ppm. The Nd distribution was determined by fluorescence imaging to be homogeneous throughout the sample. Output power of 4.9 W with a slope efficiency of 52.7% was obtained in 1.5-mm-thick Nd:YAG ceramic under a quasi-continuous wave (QCW) laser diode end pumping at 805 nm.