Evaluating the influence of marine protected areas on surf zone fish.

Marine protected areas (MPAs) globally serve conservation and fisheries management goals, generating positive effects in some marine ecosystems. Surf zones and sandy beaches, critical ecotones bridging land and sea, play a pivotal role in the life cycles of numerous fish species and serve as prime areas for subsistence and recreational fishing. Despite their significance, these areas remain understudied when evaluating the effects of MPAs. We compared surf zone fish assemblages inside and outside MPAs across 3 bioregions in California (USA). Using seines and baited remote underwater videos (BRUVs), we found differences in surf zone fish inside and outside MPAs in one region. Inside south region MPAs, we observed higher abundance (Tukey's honest significant difference [HSD] = 0.83, p = 0.0001) and richness (HSD = 0.22, p = 0.0001) in BRUVs and greater biomass (HSD = 0.32, p = 0.0002) in seine surveys compared with reference sites. Selected live-bearing, fished taxa were positively affected by MPAs. Elasmobranchs displayed greater abundance in BRUV surveys and higher biomass in seine surveys inside south region MPAs (HSD = 0.35, p = 0.0003 and HSD = 0.23, p = 0.008, respectively). Although we observed no overall MPA signal for Embiotocidae, abundances of juvenile and large adult barred surfperch (Amphistichus argenteus), the most abundant fished species, were higher inside MPAs (K-S test D = 0.19, p < 0.0001). Influence of habitat characteristics on MPA performance indicated surf zone width was positively associated with fish abundance and biomass but negatively associated with richness. The south region had the largest positive effect size on all MPA performance metrics. Our findings underscored the variability in species richness and composition across regions and survey methods that significantly affected differences observed inside and outside MPAs. A comprehensive assessment of MPA performance should consider specific taxa, their distribution, and the effects of habitat factors and geography.

Evaluación de la influencia de las áreas marinas protegidas sobre los peces de la zona de rompientes Resumen Las áreas marinas protegidas (AMP) cumplen los objetivos de conservación y manejo de pesquerías a nivel mundial, lo que genera efectos positivos en algunos ecosistemas marinos. Las zonas de rompientes y las playas arenosas, ecotonos importantes que conectan la tierra con el mar, tienen un papel esencial en el ciclo de vida de varios peces y fungen como áreas óptimas para la pesca recreativa y de sustento. A pesar de su importancia, estas áreas están poco estudiadas con respecto a la evaluación del efecto de las AMP. Comparamos la composición de peces del área de rompientes dentro y fuera de las AMP de tres bioregiones de California, EUA. Usamos chinchorros y videos submarinos con carnada (BRUVs) y descubrimos diferencias en los peces de la zona de rompientes dentro y fuera de las AMP en una región. Dentro de las AMP de la región sur observamos una mayor abundancia (diferencia significativa honesta de Tukey [DSH]  =  0.83, p = 0.0001) y riqueza (DSH  =  0.22, p = 0.0001) en los BRUV y una mayor biomasa (DSH  =  0.32, p = 0.0002) en los censos con chinchorro en comparación con los sitios de referencia. Los taxones seleccionados de peces de sustento fueron afectados de manera positiva por las AMP. Los elasmobranquios mostraron una mayor abundancia en los BRUV y una mayor biomasa en los censos con chinchorro dentro de las AMP de la región sur (DSH  =  0.35, p = 0.0003 y DSH  =  0.23, p = 0.008, respectivamente). Aunque no observamos una señal generalizada de las AMP para la familia Embiotocidae, la abundancia de Amphistichus argenteus juveniles y adultos, la especie pescada más abundante, fue mayor dentro de las AMP (prueba K­S D  =  0.19, p < 0.0001). La influencia de las características del hábitat sobre el desempeño de las AMP indicó que el ancho de la zona de rompientes está asociado de forma positiva con la abundancia y biomasa de los peces, pero de forma negativa con la riqueza. La región sur tuvo el mayor tamaño de efecto positivo sobre todas las medidas de desempeño de las AMP. Nuestros hallazgos destacan la variabilidad en la riqueza y composición de especies en todas las regiones y los censos que afectan significativamente las diferencias observadas dentro y fuera de las AMP. Una evaluación completa del desempeño de las AMP debe considerar taxones específicos, su distribución y el efecto de los factores de hábitat y la geografía.

Risk Factors for Venous Thromboembolism and Eventual Amputation in Traumatic Femoral and Iliac Vein Injuries: A Trauma Quality Improvement Program Analysis.

BACKGROUND: Iliac and femoral venous injuries represent a challenging dilemma in trauma surgery with mixed results. Venous restoration of outflow (via repair or bypass) has been previously identified as having higher rates of VTE (venous thromboembolism) compared to ligation. We hypothesized that rates of VTE and eventual amputation were similar whether restoration of venous outflow vs ligation was performed at initial operation. METHODS: Patients in the 2019-2021 National Trauma Data Bank with iliac and femoral vein injuries were abstracted and analyzed. The primary outcomes of interest were in-hospital lower extremity amputation and VTE. RESULTS: A total of 2642 patients with operatively managed iliac and femoral vein injuries were identified VTE was found in 10.8% of patients. Multivariable logistic regression was performed and identified bowel injury, higher ISS, older age, open repair, and longer time to VTE prophylaxis initiation as independent predictors of VTE. Amputation was required in 4.2% of patients. Multivariable logistic regression identified arterial or nerve injury, femur or tibia fracture, venous ligation, percutaneous intervention, fasciotomy, bowel injury, and higher ISS as independent factors of amputation. CONCLUSION: Venous restoration was not an independent predictor of VTE. Venous ligation on index operation was the only modifiable independent predictor of amputation identified on regression analysis.

Risk factors for postoperative complications in preterm infants with surgical necrotizing enterocolitis and associated outcomes.

BACKGROUND: We aim to determine clinical risk factors for postoperative complications in preterm infants with surgical necrotizing enterocolitis (NEC) or spontaneous intestinal perforation (SIP). METHODS: A retrospective cohort study of preterm infants with surgical NEC or SIP to compare clinical factors between those with and without postoperative complications. RESULTS: 78/109 (71.5%) infants had any complication following surgical NEC. Adhesions (20/35, 57.1%) and wound infection (6/35, 17.1%) were the most common single surgical complications. Patients with a single surgical complication (35/66, 53%) were significantly less likely to be exposed to antenatal steroids, more frequently had a jejunostomy, needed a central line longer, and had a longer length of stay than those without any surgical complication. Infants with > 1 surgical complication (43/71, 60.5%) included mainly females, and had AKI more frequently at NEC onset, lower weight z-scores and lower weight for length z- scores at 36 weeks PMA than those without any complications.On multinomial logistic regression, antenatal steroids exposure (OR 0.23 [CI 0.06, 0.84]; p = 0.027) was independently associated with lower risk and jejunostomy 4.81 (1.29, 17.9) was independently associated with higher risk of developing a single complication. AKI following disease onset (OR 5.33 (1.38, 20.6), P = 0.015) was independently associated with > 1 complication in surgical NEC/SIP infants. CONCLUSION: Infants with postoperative complications following surgical NEC were more likely to be female, have additional morbidities, and demonstrate growth failure at 36 weeks PMA than those without surgical complications. There was no difference in mortality between those with and without surgical complications.

Radiomics in diffusion data: a test-retest, inter- and intra-reader DWI phantom study.

AIM: The aim of this study was to evaluate the robustness of radiomics features of a MRI (magnetic resonance imaging) phantom in quantitative diffusion-weighted imaging (DWI) and depending on the image resolution. MATERIALS AND METHODS: Scanning of an in-house developed DWI phantom was performed at a 1.5 T MRI scanner (Magnetom AERA, Siemens, Erlangen, Germany) using an echo planar imaging (EPI) DWI sequence (b=0,500,1,000 s/mm2) with low (3×3 mm2) and high (2×2 mm2) image resolutions. Scans were repeated after phantom repositioning to evaluate retest reliability. Radiomics features were extracted after semi-automatic segmentation and standardised pre-processing. Intra-/interobserver reproducibility and test-retest robustness were assessed using intraclass correlation coefficients (ICC). Differences were tested with non-parametric Wilcoxon's signed-rank and Friedman's test (p < 0.05) with Dunn's post-hoc analysis. RESULTS: Test-retest ICC was overall high with >0.90 for 39/46 radiomics features in all sequences/resolutions. Decreased test-retest ICCs were pronounced for conventional Min-value (overall ICC=0.817), and grey-level zone length matrix (GLZLM) features Short-Zone Emphasis (SZE) and Short-Zone Low Grey-level Emphasis (SZLGE) (for both overall ICC=0.927). Test-retest reproducibility was significantly different between b=500, 1,000 and apparent diffusion coefficient (ADC) (mean 0.975±0.050, 0.974±0.051 and 0.966±0.063), which remained significant after post-hoc analysis between b=1,000 and ADC (p = 0.022). ICCs were not significantly different between resolutions of 2×2 and 3×3 mm2 regarding b=500 (mean: 0.977±0.052 and 0.974±0.049, p = 0.612), b=1,000 (mean: 0.973±0.059 and 0.974±0.054, p = 0.516), and ADC (mean: 0.972±0.049 and 0.955±0.101, p = 0.851). Inter- and intra-observer reliability was consistently high for all sequences (overall mean 0.992±0.021 and 0.990±0.028). CONCLUSION: Under ex-vivo conditions, DWI provided robust radiomics features with those from ADC being slightly less robust than from raw DWI (b=500, 1,000 s/mm2). No significant difference was detected for different resolutions. Although, ex-vivo reliability of DWI radiomics features was high, no implications can be made regarding in-vivo analyses.

What remains after transient global amnesia (TGA)? An ultra-high field 7 T magnetic resonance imaging study of the hippocampus.

BACKGROUND AND PURPOSE: The aim was to study whether ultra-high field 7 T magnetic resonance imaging (MRI) can demonstrate chronic focal defects in the hippocampus corresponding to the former acute diffusion-weighted imaging (DWI) lesions and to assess chronic T2-hyperintense hippocampal lesion load in transient global amnesia (TGA) patients. METHODS: Follow-up of 7 T MRI of the hippocampus was performed in 13 patients with documented hippocampal DWI lesions (detected via 3 T MRI) after acute TGA. The location of the DWI lesions was transformed to 7 T T2 images after data co-registration. Additionally, the T2-hyperintense lesion load was estimated in each patient and compared with that of 13 healthy controls. RESULTS: Magnetic resonance imaging (7 T) was performed after a median of 4 months. No structural abnormality at the site of the previous TGA lesion was observed in any case. None of the controls showed DWI lesions. There was no significant difference between patients and controls concerning the number (P = 0.67) or volume (P = 0.45) of T2-hyperintense hippocampal lesions. CONCLUSIONS: Diffusion-weighted imaging lesions in patients with TGA do not provoke any visible sequelae and do not result in hippocampal cavities. The occurrence of incidental hippocampal T2 lesions after TGA is not more frequent than in controls.

Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season.

BACKGROUND: Species distribution models have shown that blue whales (Balaenoptera musculus) occur seasonally in high densities in the most biologically productive regions of the California Current Ecosystem (CCE). Satellite telemetry studies have additionally shown that blue whales in the CCE regularly switch between behavioral states consistent with area-restricted searching (ARS) and transiting, indicative of foraging in and moving among prey patches, respectively. However, the relationship between the environmental correlates that serve as a proxy of prey relative to blue whale movement behavior has not been quantitatively assessed. METHODS: We investigated the association between blue whale behavioral state and environmental predictors in the coastal environments of the CCE using a long-term satellite tracking data set (72 tagged whales; summer-fall months 1998-2008), and predicted the likelihood of ARS behavior at tracked locations using nonparametric multiplicative regression models. The models were built using data from years of cool, productive conditions and validated against years of warm, low-productivity conditions. RESULTS: The best model contained four predictors: chlorophyll-a, sea surface temperature, and seafloor aspect and depth. This model estimated highest ARS likelihood (> 0.8) in areas with high chlorophyll-a levels (> 0.65 mg/m3), intermediate sea surface temperatures (11.6-17.5 °C), and shallow depths (< 850 m). Overall, the model correctly predicted behavioral state throughout the coastal environments of the CCE, while the validation indicated an ecosystem-wide reduction in ARS likelihood during warm years, especially in the southern portion. For comparison, a spatial coordinates model (longitude × latitude) performed slightly better than the environmental model during warm years, providing further evidence that blue whales exhibit strong foraging site fidelity, even when conditions are not conducive to successful foraging. CONCLUSIONS: We showed that blue whale behavioral state in the CCE was predictable from environmental correlates and that ARS behavior was most prevalent in regions of known high whale density, likely reflecting where large prey aggregations consistently develop in summer-fall. Our models of whale movement behavior enhanced our understanding of species distribution by further indicating where foraging was more likely, which could be of value in the identification of key regions of importance for endangered species in management considerations. The models also provided evidence that decadal-scale environmental fluctuations can drive shifts in the distribution and foraging success of this blue whale population.

Wall Contrast Enhancement of Thrombosed Intracranial Aneurysms at 7T MRI.

BACKGROUND AND PURPOSE: The pathophysiology of wall contrast enhancement in thrombosed intracranial aneurysms is incompletely understood. This in vivo study aimed to investigate wall microstructures with gadolinium-enhanced 7T MR imaging. MATERIALS AND METHODS: Thirteen patients with 14 thrombosed intracranial aneurysms were evaluated using a 7T whole-body MR imaging system with nonenhanced and gadolinium-enhanced high-resolution MPRAGE. Tissue samples were available in 5 cases, and histopathologic findings were correlated with 7T MR imaging to identify the gadolinium-enhancing microstructures. RESULTS: Partial or complete inner wall enhancement correlated with neovascularization of the inner wall layer and the adjacent thrombus. Additional partial or complete outer wall enhancement can be explained by formation of vasa vasorum in the outer aneurysm wall layer. The double-rim enhancement correlated with perifocal edema and wall histologic findings suggestive of instability. CONCLUSIONS: Two distinct aneurysm wall microstructures responsible for gadolinium enhancement not depictable at lower spatial resolutions can be visualized in vivo using high-resolution gadolinium-enhanced 7T MR imaging.

Memory and resource tracking drive blue whale migrations.

In terrestrial systems, the green wave hypothesis posits that migrating animals can enhance foraging opportunities by tracking phenological variation in high-quality forage across space (i.e., "resource waves"). To track resource waves, animals may rely on proximate cues and/or memory of long-term average phenologies. Although there is growing evidence of resource tracking in terrestrial migrants, such drivers remain unevaluated in migratory marine megafauna. Here we present a test of the green wave hypothesis in a marine system. We compare 10 years of blue whale movement data with the timing of the spring phytoplankton bloom resulting in increased prey availability in the California Current Ecosystem, allowing us to investigate resource tracking both contemporaneously (response to proximate cues) and based on climatological conditions (memory) during migrations. Blue whales closely tracked the long-term average phenology of the spring bloom, but did not track contemporaneous green-up. In addition, blue whale foraging locations were characterized by low long-term habitat variability and high long-term productivity compared with contemporaneous measurements. Results indicate that memory of long-term average conditions may have a previously underappreciated role in driving migratory movements of long-lived species in marine systems, and suggest that these animals may struggle to respond to rapid deviations from historical mean environmental conditions. Results further highlight that an ecological theory of migration is conserved across marine and terrestrial systems. Understanding the drivers of animal migration is critical for assessing how environmental changes will affect highly mobile fauna at a global scale.

Visualization and Classification of Deeply Seated Collateral Networks in Moyamoya Angiopathy with 7T MRI.

BACKGROUND AND PURPOSE: Collateral networks in Moyamoya angiopathy have a complex angioarchitecture difficult to comprehend on conventional examinations. This study aimed to evaluate morphologic patterns and the delineation of deeply seated collateral networks using ultra-high-field MRA in comparison with conventional DSA. MATERIALS AND METHODS: Fifteen white patients with Moyamoya angiopathy were investigated in this prospective trial. Sequences acquired at 7T were TOF-MRA with 0.22 × 0.22 × 0.41 mm3 resolution and MPRAGE with 0.7 × 0.7 × 0.7 mm3 resolution. Four raters evaluated the presence of deeply seated collateral networks and image quality in a consensus reading of DSA, TOF-MRA, and MPRAGE using a 5-point scale in axial source images and maximum intensity projections. Delineation of deeply seated collateral networks by different imaging modalities was compared by means of the McNemar test, whereas image quality was compared using the Wilcoxon signed-rank test. RESULTS: The relevant deeply seated collateral networks were classified into 2 categories and 6 pathways. A total of 100 collateral networks were detected on DSA; 106, on TOF-MRA; and 73, on MPRAGE. Delineation of deeply seated collateral networks was comparable between TOF-MRA and DSA (P = .25); however, both were better than MPRAGE (P < .001). CONCLUSIONS: This study demonstrates excellent delineation of 6 distinct deeply seated collateral network pathways in Moyamoya angiopathy in white adults using 7T TOF-MRA, comparable to DSA.

Maximum intensity breast diffusion MRI for BI-RADS 4 lesions detected on X-ray mammography.

AIM: To investigate an abbreviated, contrast-agent free diffusion-weighted (DW) breast magnetic resonance imaging (MRI) protocol that provides a single image for the radiologist to read in order to non-invasively examine Breast Imaging-Reporting and Data System (BI-RADS) 4 lesions detected using breast cancer screening X-ray mammography. MATERIALS AND METHODS: This retrospective evaluation within a institutional review board-approved, prospective study included 115 women (mean 57 years, range 50-69 years) with BI-RADS 4 findings on X-ray mammography and indication for biopsy over a period of 15 months. Full diagnostic breast MRI (FDP) was performed prior to biopsy (1.5 T). Maximum intensity breast diffusion (MIBD) images were generated from DW images (b = 1,500 mm/s2, 3 mm section thickness) of the breast. MIBD and T2-weighted (T2W) images were read by two radiologists and compared to the diagnostic accuracy of an expert reading of the FDP with histopathology as the reference standard. The acquisition time of MIBD and T2W MRI was about 7 minutes. RESULTS: MIBD MRI provided a diagnostic accuracy of 87.93% (95% confidence interval [CI]: 80.58-93.24%) for R1 and 89.66% (95% CI: 82.63-94.54%) for R2. Expert reading of the FDP revealed a similar accuracy of 86.2% (95% CI: 78.67-91.43%). The positive predictive value (PPV) could be increased from 36.2% (95% CI: 28.02-45.28; X-ray mammography alone) to a mean PPV of 80.89% (R1 79.17%, R2 82.16%) using MIBD MRI. Mean reading time was 30 seconds (25%/75 percentile 24.5-41.25). CONCLUSIONS: MIBD MRI might be of supplemental value if added to the work-up of BI-RADS 4 X-ray mammography screening findings. MIBD MRI might help reduce the false-positive rate prior to biopsy for reference lesions at only limited expense of measurement and reading time.

The development of an intermediate-duration tag to characterize the diving behavior of large whales.

The development of high-resolution archival tag technologies has revolutionized our understanding of diving behavior in marine taxa such as sharks, turtles, and seals during their wide-ranging movements. However, similar applications for large whales have lagged behind due to the difficulty of keeping tags on the animals for extended periods of time. Here, we present a novel configuration of a transdermally attached biologging device called the Advanced Dive Behavior (ADB) tag. The ADB tag contains sensors that record hydrostatic pressure, three-axis accelerometers, magnetometers, water temperature, and light level, all sampled at 1 Hz. The ADB tag also collects Fastloc GPS locations and can send dive summary data through Service Argos, while staying attached to a whale for typical periods of 3-7 weeks before releasing for recovery and subsequent data download. ADB tags were deployed on sperm whales (Physeter macrocephalus; N = 46), blue whales (Balaenoptera musculus; N = 8), and fin whales (B. physalus; N = 5) from 2007 to 2015, resulting in attachment durations from 0 to 49.6 days, and recording 31 to 2,539 GPS locations and 27 to 2,918 dives per deployment. Archived dive profiles matched well with published dive shapes of each species from short-term records. For blue and fin whales, feeding lunges were detected using peaks in accelerometer data and matched corresponding vertical excursions in the depth record. In sperm whales, rapid orientation changes in the accelerometer data, often during the bottom phase of dives, were likely related to prey pursuit, representing a relative measure of foraging effort. Sperm whales were documented repeatedly diving to, and likely foraging along, the seafloor. Data from the temperature sensor described the vertical structure of the water column in all three species, extending from the surface to depths >1,600 m. In addition to providing information needed to construct multiweek time budgets, the ADB tag is well suited to studying the effects of anthropogenic sound on whales by allowing for pre- and post-exposure monitoring of the whale's dive behavior. This tag begins to bridge the gap between existing long-duration but low-data throughput tags, and short-duration, high-resolution data loggers.

Ventricular Microaneurysms in Moyamoya Angiopathy Visualized with 7T MR Angiography.

The pathophysiologic role of hemodynamic alteration to peripheral vessels in Moyamoya angiopathy and the formation of microaneurysms remains unclear. The purpose of this study was to investigate microaneurysms in collateral Moyamoya vessels by using 7T ultra-high-field MR imaging. Ten patients with Moyamoya disease were evaluated with TOF-MRA at 7T acquired with 0.22 × 0.22 × 0.41 mm(3) resolution. In 10 patients, 4 microaneuryms located in the ventricles were delineated. The mean diameters of collateral vessels and microaneurysms arising from those vessels were 0.87 mm (range, 0.79-1.07 mm) and 0.80 mm (range, 0.56-0.96 mm), respectively. In 1 case with follow-up scans 6 months after a direct extracranial-intracranial bypass operation, the microaneurysm disappeared. Ventricular microaneurysms in Moyamoya angiopathy collateral vessels, inaccessible by conventional imaging techniques, can be detected by 7T TOF-MRA.

Pronounced reduction of acquisition of conditioned eyeblink responses in young adults with focal cerebellar lesions impedes conclusions on the role of the cerebellum in extinction and savings.

Human cerebellar lesion studies provide good evidence that the cerebellum contributes to the acquisition of classically conditioned eyeblink responses (CRs). As yet, only one study used more advanced methods of lesion-symptom (or lesion-behavior) mapping to investigate which cerebellar areas are involved in CR acquisition in humans. Likewise, comparatively few studies investigated the contribution of the human cerebellum to CR extinction and savings. In this present study, young adults with focal cerebellar disease were tested. A subset of participants was expected to acquire enough conditioned responses to allow the investigation of extinction and saving effects. 19 participants with chronic surgical lesions of the cerebellum and 19 matched control subjects were tested. In all cerebellar subjects benign tumors of the cerebellum had been surgically removed. Eyeblink conditioning was performed using a standard short delay protocol. An initial unpaired control phase was followed by an acquisition phase, an extinction phase and a subsequent reacquisition phase. Structural 3T magnetic resonance images of the brain were acquired on the day of testing. Cerebellar lesions were normalized using methods optimized for the cerebellum. Subtraction analysis and Liebermeister tests were used to perform lesion-symptom mapping. As expected, CR acquisition was significantly reduced in cerebellar subjects compared to controls. Reduced CR acquisition was significantly more likely in participants with lesions of lobule VI and Crus I extending into Crus II (p<0.05, Liebermeister test). Cerebellar subjects could be subdivided into two groups: a smaller group (n=5) which showed acquisition, extinction and savings within the normal range; and a larger group (n=14) which did not show acquisition. In the latter, no conclusions on extinction or savings could be drawn. Previous findings were confirmed that circumscribed areas in lobule VI and Crus I are of major importance in CR acquisition. In addition, the present data suggest that if the critical regions of the cerebellar cortex are lesioned, the ability to acquire CRs is not only reduced but abolished. Subjects with lesions outside these critical areas, on the other hand show preserved acquisition, extinction and saving effects. As a consequence, studies in human subjects with cerebellar lesions do not allow drawing conclusions on CR extinction and savings. In light of the present findings, previous reports of reduced extinction in humans with circumscribed cerebellar disease need to be critically reevaluated.

Cerebellar fMRI Activation Increases with Increasing Working Memory Demands.

The aim of the present study was to explore cerebellar contributions to the central executive in n-back working memory tasks using 7-T functional magnetic imaging (fMRI). We hypothesized that cerebellar activation increased with increasing working memory demands. Activations of the cerebellar cortex and dentate nuclei were compared between 0-back (serving as a motor control task), 1-back, and 2-back working memory tasks for both verbal and abstract modalities. A block design was used. Data of 27 participants (mean age 26.6 ± 3.8 years, female/male 12:15) were included in group statistical analysis. We observed that cerebellar cortical activations increased with higher central executive demands in n-back tasks independent of task modality. As confirmed by subtraction analyses, additional bilateral activations following higher executive demands were found primarily in four distinct cerebellar areas: (i) the border region of lobule VI and crus I, (ii) inferior parts of the lateral cerebellum (lobules crus II, VIIb, VIII, IX), (iii) posterior parts of the paravermal cerebellar cortex (lobules VI, crus I, crus II), and (iv) the inferior vermis (lobules VI, VIIb, VIII, IX). Dentate activations were observed for both verbal and abstract modalities. Task-related increases were less robust and detected for the verbal n-back tasks only. These results provide further evidence that the cerebellum participates in an amodal bilateral neuronal network representing the central executive during working memory n-back tasks.

Critically endangered western gray whales migrate to the eastern North Pacific.

Western North Pacific gray whales (WGWs), once considered extinct, are critically endangered with unknown migratory routes and reproductive areas. We attached satellite-monitored tags to seven WGWs on their primary feeding ground off Sakhalin Island, Russia, three of which subsequently migrated to regions occupied by non-endangered eastern gray whales (EGWs). A female with the longest-lasting tag visited all three major EGW reproductive areas off Baja California, Mexico, before returning to Sakhalin Island the following spring. Her 22 511 km round-trip is the longest documented mammal migration and strongly suggests that some presumed WGWs are actually EGWs foraging in areas historically attributed to WGWs. The observed migration routes provide evidence of navigational skills across open water that break the near-shore north-south migratory paradigm of EGWs. Despite evidence of genetic differentiation, these tagging data indicate that the population identity of whales off Sakhalin Island needs further evaluation.

Cerebellar Contribution to Context Processing in Extinction Learning and Recall.

Whereas acquisition of new associations is considered largely independent of the context, context dependency is a hallmark of extinction of the learned associations. The hippocampus and the prefrontal cortex are known to be involved in context processing during extinction learning and recall. Although the cerebellum has known functional and anatomic connections to the hippocampus and the prefrontal cortex, cerebellar contributions to context processing of extinction have rarely been studied. In the present study, we reanalyzed functional brain imaging data (fMRI) of previous work investigating context effects during extinction in a cognitive associative learning paradigm in 28 young and healthy subjects (Lissek et al. Neuroimage. 81:131-3, 2013). In that study, event-related fMRI analysis did not include the cerebellum. The 3 T fMRI dataset was reanalyzed using a spatial normalization method optimized for the cerebellum. Data of seven participants had to be excluded because the cerebellum had not been scanned in full. Cerebellar activation related to context change during extinction learning was most prominent in lobule Crus II bilaterally (p < 0.01, t > 2.53; partially corrected by predetermined cluster size). No significant cerebellar activations were observed related to context change during extinction retrieval. The posterolateral cerebellum appears to contribute to context-related processes during extinction learning, but not (or less) during extinction retrieval. The cerebellum may support context learning during extinction via its connections to the hippocampus. Alternatively, the cerebellum may support the shifting of attention to the context via its known connections to the dorsolateral prefrontal cortex. Because the ventromedial prefrontal cortex (vmPFC) is critically involved in context-related processes during extinction retrieval, and there are no known connections between the cerebellum and the vmPFC, the cerebellum may be less important during extinction recall.

Brain tumours at 7T MRI compared to 3T--contrast effect after half and full standard contrast agent dose: initial results.

OBJECTIVES: To compare the contrast agent effect of a full dose and half the dose of gadobenate dimeglumine in brain tumours at 7 Tesla (7 T) MR versus 3 Tesla (3T). METHODS: Ten patients with primary brain tumours or metastases were examined. Signal intensities were assessed in the lesion and normal brain. Tumour-to-brain contrast and lesion enhancement were calculated. Additionally, two independent readers subjectively graded the image quality and artefacts. RESULTS: The enhanced mean tumour-to-brain contrast and lesion enhancement were significantly higher at 7 T than at 3T for both half the dose (91.8 ± 45.8 vs. 43.9 ± 25.3 [p = 0.010], 128.1 ± 53.7 vs. 75.5 ± 32.4 [p = 0.004]) and the full dose (129.2 ± 50.9 vs. 66.6 ± 33.1 [p = 0.002], 165.4 ± 54.2 vs. 102.6 ± 45.4 [p = 0.004]). Differences between dosages at each field strength were also significant. Lesion enhancement was higher with half the dose at 7 T than with the full dose at 3T (p = .037), while the tumour-to-brain contrast was not significantly different. Subjectively, contrast enhancement, visibility, and lesion delineation were better at 7 T and with the full dose. All parameters were rated as good, at the least. CONCLUSION: Half the routine contrast agent dose at 7 T provided higher lesion enhancement than the full dose at 3T which indicates the possibility of dose reduction at 7 T. KEY POINTS: • The contrast effect of gadobenate dimeglumine was assessed at 7 T and 3T. • In brain tumours, contrast effect was higher at 7 T than at 3T. • Tumour-to-brain contrast at 7 T half dose and 3T full dose were comparable. • 7 T half dose lesion enhancement was higher than 3T full dose enhancement. • Our results indicate the possibility of contrast agent dose reduction at 7 T.

Cerebellar pathology in Friedreich's ataxia: atrophied dentate nuclei with normal iron content.

BACKGROUND: In Friedreich's ataxia (FA) the genetically decreased expression of the mitochondrial protein frataxin leads to disturbance of the mitochondrial iron metabolism. Within the cerebellum the dentate nuclei (DN) are primarily affected. Histopathological studies show atrophy and accumulation of mitochondrial iron in DN. Dentate iron content has been suggested as a biomarker to measure the effects of siderophores/antioxidant treatment of FA. We assessed the iron content and the volume of DN in FA patients and controls based on ultra-high-field MRI (7 Tesla) images. METHODS: Fourteen FA patients (mean age 38.1 yrs) and 14 age- and gender-matched controls participated. Multi-echo gradient echo and susceptibility weighted imaging (SWI) sequences were acquired on a 7 T whole-body scanner. For comparison SWI images were acquired on a 1.5 T MR scanner. Volumes of the DN and cerebellum were assessed at 7 and 1.5 T, respectively. Parametric maps of T2 and T2* sequences were created and proton transverse relaxation rates were estimated as a measure of iron content. RESULTS: In FA, the DN and the cerebellum were significantly smaller compared to controls. However, proton transverse relaxation rates of the DN were not significantly different between both groups. CONCLUSIONS: Applying in vivo MRI methods we could demonstrate significant atrophy of the DN in the presence of normal iron content. The findings suggest that relaxation rates are not reliable biomarkers in clinical trials evaluating the potential effect of FA therapy.