Default Mode and Executive Networks Areas: Association with the Serial Order in Divergent Thinking.

Scientific findings have suggested a two-fold structure of the cognitive process. By using the heuristic thinking mode, people automatically process information that tends to be invariant across days, whereas by using the explicit thinking mode people explicitly process information that tends to be variant compared to typical previously learned information patterns. Previous studies on creativity found an association between creativity and the brain regions in the prefrontal cortex, the anterior cingulate cortex, the default mode network and the executive network. However, which neural networks contribute to the explicit mode of thinking during idea generation remains an open question. We employed an fMRI paradigm to examine which brain regions were activated when participants (n = 16) mentally generated alternative uses for everyday objects. Most previous creativity studies required participants to verbalize responses during idea generation, whereas in this study participants produced mental alternatives without verbalizing. This study found activation in the left anterior insula when contrasting idea generation and object identification. This finding suggests that the insula (part of the brain's salience network) plays a role in facilitating both the central executive and default mode networks to activate idea generation. We also investigated closely the effect of the serial order of idea being generated on brain responses: The amplitude of fMRI responses correlated positively with the serial order of idea being generated in the anterior cingulate cortex, which is part of the central executive network. Positive correlation with the serial order was also observed in the regions typically assigned to the default mode network: the precuneus/cuneus, inferior parietal lobule and posterior cingulate cortex. These networks support the explicit mode of thinking and help the individual to convert conventional mental models to new ones. The serial order correlated negatively with the BOLD responses in the posterior presupplementary motor area, left premotor cortex, right cerebellum and left inferior frontal gyrus. This finding might imply that idea generation without a verbal processing demand reflecting lack of need for new object identification in idea generation events. The results of the study are consistent with recent creativity studies, which emphasize that the creativity process involves working memory capacity to spontaneously shift between different kinds of thinking modes according to the context.

Effectiveness of intravesical hyaluronic acid with or without chondroitin sulfate for recurrent bacterial cystitis in adult women: a meta-analysis.

INTRODUCTION AND HYPOTHESIS: Glycosaminoglycan hyaluronic acid (HA) and chondroitin sulphate (CS) protect the urothelium. Damage to the urothelium may increase bacterial adherence and infection risk. This meta-analysis evaluated the effect of intravesical HA and HA and CS (HA-CS) combination therapy in recurrent bacterial cystitis (RBC) in adult women. METHODS: A systematic literature search was performed. Primary outcomes were urinary tract infection (UTI) rate per patient-year, and UTI recurrence time (days). Secondary outcomes were 3-day voids and Pelvic Pain and Urgency/Frequency (PUF) symptom scale total score. RESULTS: Four studies involving a total of 143 patients were retrieved and assessed in this analysis. Two were randomized, and two were nonrandomized. A significantly decreased UTI rate per patient-year [mean difference (MD) -3.41, 95 % confidence interval (CI) -4.33 to -2.49, p < 0.00001) was found. Similarly, pooled analysis showed a significantly longer mean UTI recurrence time (days) using either HA or HA-CS therapy (MD 187.35, 95 % CI 94.33-280.37, p < 0.0001). Two studies using HA and HA-CS therapy reported outcomes on 3-day voids, which were not significantly improved after therapy (MD -3.59, 95 % CI -8.43-1.25, p = 0.15), but a significantly better PUF total score (MD -7.17, 95 % CI -9.86 to -4.48, p < 0.00001) was detected in HA-CS groups. CONCLUSIONS: Intravesical HA and HA-CS in combination significantly reduced cystitis recurrence, mean UTI recurrence time, and PUF total score. Study limitations include the small number of patients and possible bias. Further studies are needed to validate this promising treatment modality.

High-resolution TOF MR angiography at 4.7 Tesla for volumetric and morphologic evaluation of coiled aneurysm neck remnants in a rat model.

BACKGROUND: Detection of morphologic and volumetric changes in aneurysm necks is important when evaluating the effects of endovascular devices for aneurysm occlusion. PURPOSE: To optimize high-resolution 3D-TOF MRA at 4.7 T in order to achieve the best aneurysm-to-background contrast in experimental rat aneurysms, and to quantify the volume of the aneurysm neck by imaging. MATERIAL AND METHODS: Saccular aneurysms in the abdominal aorta of rats were coiled with platinum coils. Tissue relaxation times were measured, and used in a mathematical simulation. To optimize 3D-TOF angiography, imaging parameters were varied within the range obtained from the simulations. Tissue contrast and contrast-to-noise ratio were measured from MR images. TOF images were compared to conventional spin echo and gradient echo images and to endoscopic and histological analyses. RESULTS: Parameters yielding the best aneurysm-to-background contrast and contrast-to-noise ratio were determined. The agreement between the results from in vivo imaging and simulation was good. The optimized 3D-TOF MRA sequence (TR/TE/FA = 60 ms/6.6 ms/20°) had an isotropic voxel size of 117 µm, which enabled measurement of the aneurysm neck volume. CONCLUSION: High-resolution 3D-TOF angiography enables non-invasive quantification of changes in neck remnants of endovascularly coiled experimental aneurysms. In this model innovations like bioactive coils can be accurately tested for their efficacy for aneurysm occlusion.

Optimization of high-resolution USPIO magnetic resonance imaging at 4.7 T using novel phantom with minimal structural interference.

PURPOSE: To characterize the effect of ultrasmall superparamagnetic iron oxides (USPIOs) on magnetic resonance imaging (MRI) signal at 4.7 T, and to find the highest sensitivity pulse sequence for high-resolution USPIO MRI. MATERIALS AND METHODS: A novel phantom was constructed for optimization of sequence parameters for neuroradiological MR applications, and a wide range of dilutions of the USPIO ferumoxtran-10 was imaged using T(2)/T(1)-, T(1)-, T(2)-, T* (2)-, and PD-weighted sequences. The effect of varying sequence parameters was investigated using phantom measurements and simulations. RESULTS: The relaxivities r(1), r(2), and r*(2) of ferumoxtran-10 at 4.7 T (21°C) were 5.1, 82.2, and 148.4 mmol(-1) L s(-1), respectively. Gradient echo sequences produced superior susceptibility artifacts at high concentrations; susceptibility artifacts were seen down to a concentration of 137 nmol Fe/mL. A concentration of 17.5 µmol Fe/mL caused a signal void independently of sequence and parameters, and at concentrations ≤273 nmol Fe/mL no signal void was caused. Signal enhancement on T(1)-weighted imaging was seen only at concentrations 137-547 nmol Fe/mL. For the same effective echo time T(2)-weighted rapid acquisition with relaxation enhancement (RARE) yielded significantly higher contrast-to-noise ratio with RARE factor 16 than with RARE factor 8. CONCLUSION: At nanomolar concentrations of USPIO, steady-state free precession offers an alternative to T(2)- and T*(2)-weighted sequences. Optimum parameters depend highly on USPIO concentration.

Magnetic fields evoked by speech sounds in preschool children.

OBJECTIVE: Our objective was to study how well the auditory evoked magnetic fields (EF) reflect the behavioral discrimination of speech sounds in preschool children, and if they reveal the same information as simultaneously recorded evoked potentials (EP). METHODS: EFs and EPs were recorded in 11 preschool children (mean age 6 years 9 months) using an oddball paradigm with two sets of speech stimuli consisting both of one standard and two deviants. After the brain activity recording, children were tested on behavioural discrimination of the same stimuli presented in pairs. RESULTS: There was a mismatch negativity (MMN) calculated from difference curves and its magnetic counterpart MMNm measured from the original responses only to those deviants, which were behaviourally easiest to discriminate from the standards. In addition, EF revealed significant differences between the locations of the activation depending on the hemisphere and stimulus properties. CONCLUSIONS: EF, in addition to reflecting the sound-discrimination accuracy in a similar manner as EP, also reflected the spatial differences in activation of the temporal lobes. SIGNIFICANCE: These results suggest that both EPs and EFs are feasible for investigating the neural basis of sound discrimination in young children. The recording of EFs with its high spatial resolution reveals information on the location of the activated neural sources.