Dissociable Temporo-Parietal Memory Networks Revealed by Functional Connectivity during Episodic Retrieval

Episodic memory retrieval most often recruits multiple separate processes that are thought to involve different temporal regions. Previous studies suggest dissociable regions in the left lateral parietal cortex that are associated with the retrieval processes. Moreover, studies using resting-state functional connectivity (RSFC) have provided evidence for the temporo-parietal memory networks that may support the retrieval processes. In this functional MRI study, we tested functional significance of the memory networks by examining functional connectivity of brain activity during episodic retrieval in the temporal and parietal regions of the memory networks. Recency judgments, judgments of the temporal order of past events, can be achieved by at least two retrieval processes, relational and item-based. Neuroimaging results revealed several temporal and parietal activations associated with relational/item-based recency judgments. Significant RSFC was observed between one parahippocampal region and one left lateral parietal region associated with relational recency judgments, and between four lateral temporal regions and another left lateral parietal region associated with item-based recency judgments. Functional connectivity during task was found to be significant between the parahippocampal region and the parietal region in the RSFC network associated with relational recency judgments. However, out of the four tempo-parietal RSFC networks associated with item-based recency judgments, only one of them (between the left posterior lateral temporal region and the left lateral parietal region) showed significant functional connectivity during task. These results highlight the contrasting roles of the parahippocampal and the lateral temporal regions in recency judgments, and suggest that only a part of the tempo-parietal RSFC networks are recruited to support particular retrieval processes.     

Difference in cesium accumulation among rice cultivars grown in the paddy field in Fukushima Prefecture in 2011 and 2012

After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plants grown in the actual paddy field in Fukushima City. We herein conducted a two-year survey in 2011 and 2012 of radioactive and non-radioactive Cs accumulation in rice using a number of rice cultivars grown in the paddy field in Fukushima City. Our study demonstrated a substantial variation in Cs accumulation levels among the cultivars of rice.     

Corticospinal tract-sparing intensity-modulated radiotherapy treatment planning

Aim

To establish intensity-modulated radiotherapy (IMRT) planning procedures that spare the corticospinal tract by integrating diffusion tensor tractography into the treatment planning software.

Background

Organs at risk are generally contoured according to the outline of the organ as demonstrated by CT or MRI. But a part of the organ with specific function is difficult to protect, because such functional part of the organ cannot be delineated on CT or conventional sequence of MRI.

Methods

Diagnostic and treatment planning images of glioblastoma patients who had been treated by conventional 3-dimensional conformal radiotherapy were used for re-planning of IMRT. Three-dimensional fiber maps of the corticospinal tracts were created from the diffusion tensors obtained from the patients before the surgery, and were blended with the anatomical MR images (i.e. gadolinium-enhanced T1-weighted images or T2-weighted images). DICOM-formatted blended images were transferred and fused to the planning CT images. Then, IMRT plans were attempted.

Results

The corticospinal tracts could be contoured as organs at risk (OARs), because the blended images contained both anatomical information and fiber-tract maps. Other OARs were contoured in a way similar to that of ordinary IMRT planning. Gross tumor volumes, clinical target volumes, planning target volumes, and other OARs were contoured on the treatment planning software, and IMRT plans were made.

Conclusions

IMRT plans with diminished doses to the corticospinal tract were attained. This technique enabled us to spare specific neuron fibers as OARs which were formerly “invisible” and to reduce the probability of late morbidities.     

Detection of Lung Tumors in Mice Using a 1-Tesla Compact Magnetic Resonance Imaging System

Due to their small size, lung tumors in rodents are typically investigated using high-field magnetic resonance (MR) systems (4.7 T or higher) to achieve higher signal-to-noise ratios, although low-field MR systems are less sensitive to susceptibility artifacts caused by air in the lung. We investigated the feasibility of detecting lung tumors in living, freely breathing mice with a 1-T compact permanent magnet MR system. In total, 4 mice were used, and MR images of mouse lungs were acquired using a T1-weighted three-dimensional fast low-angle shot sequence without cardiac or respiratory gating. The delineation and size of lung tumors were assessed and compared with histopathological findings. Submillimeter lesions were demonstrated as hyperintense, relative to the surrounding lung parenchyma, and were delineated clearly. Among the 13 lesions validated in histopathological sections, 11 were detected in MR images; the MR detection rate was thus 84.6%. A strong correlation was obtained in size measurements between MR images and histological sections. Thus, a dedicated low-field MR system can be used to detect lung tumors in living mice noninvasively without gating.     

Magnetoreception system in honeybees (Apis mellifera)

Honeybees (Apis mellifera) undergo iron biomineralization, providing the basis for magnetoreception. We showed earlier the presence of superparamagnetic magnetite in iron granules formed in honeybees, and subscribed to the notion that external magnetic fields may cause expansion or contraction of the superparamagnetic particles in an orientation-specific manner, relaying the signal via cytoskeleton (Hsu and Li 1994). In this study, we established a size-density purification procedure, with which quantitative amount of iron granules was obtained from honey bee trophocytes and characterized; the density of iron granules was determined to be 1.25 g/cm(3). While we confirmed the presence of superparamagnetic magnetite in the iron granules, we observed changes in the size of the magnetic granules in the trophycytes upon applying additional magnetic field to the cells. A concomitant release of calcium ion was observed by confocal microscope. This size fluctuation triggered the increase of intracellular Ca(+2) , which was inhibited by colchicines and latrunculin B, known to be blockers for microtubule and microfilament syntheses, respectively. The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response. A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.     

Identification of 14-3-3 proteins as a target of ATL31 ubiquitin ligase, a regulator of the C/N response in Arabidopsis

The balance between carbon (C) and nitrogen (N) availability is an important determinant for various phases of plant growth; however, the detailed mechanisms regulating the C/N response are not well understood. We previously described two related ubiquitin ligases, ATL31 and ATL6, that function in the C/N response in Arabidopsis thaliana. Here, we used FLAG tag affinity purification and MS analysis to identify proteins targeted by ATL31, and thus likely to be involved in regulating the phase transition checkpoint based on C/N status. This analysis revealed that 14-3-3 proteins were associated with ATL31, and one of these, 14-3-3χ, was selected for detailed characterization. The interaction between ATL31 and 14-3-3χ was confirmed by yeast two-hybrid and co-immunoprecipitation analyses. In vitro assays showed that ubiquitination of 14-3-3χ is catalyzed by ATL31. Degradation of 14-3-3χin vivo was shown to be correlated with ATL31 activity, and to occur in a proteasome-dependent manner. Furthermore, 14-3-3 protein accumulation was induced by a shift to high-C/N stress conditions in Arabidopsis seedlings, and this regulated response required both ATL31 and ATL6. It was also shown that over-expression of 14-3-3χ leads to hypersensitivity of Arabidopsis seedlings to C/N stress conditions. These results indicate that ATL31 targets and ubiquitinates 14-3-3 proteins for degradation via the ubiquitin-proteasome system during the response to cellular C/N status.     

How Close Should the Outer Hair Cell RC Roll-Off Frequency Be to the Characteristic Frequency?

Recent experiments have shown a much larger conductance in outer hair cells, the central components of the mammalian cochlear amplifier. The report used only the cell's linear capacitance, which together with increased conductance, raised the cell's RC corner frequency so that voltage-dependent motility was better able to amplify high-frequency sounds. We construct transfer functions for a simple model of a high characteristic frequency (CF) local cochlear resonance. These show that voltage roll-off does not occur above the RC corner. Instead, it is countered by high-pass filtering that is intrinsic to the mammal's electromechanical resonance. Thus, the RC corner of a short outer hair cell used for high-frequency amplification does not have to be close to the CF, but depending on the drag, raised only above 0.1 CF. This high-pass filter, built in to the mammalian amplifier, allows for sharp frequency selectivity at very high CF.     

After plastic surgery: adolescent-reported appearance ratings and appearance-related burdens in patient and general population groups.

The aim of this study was to determine the effects of appearance-related surgery on psychosocial functioning during adolescence. To this end, changes in bodily attitudes and appearance-related burdens in adolescents undergoing corrective (for aesthetic deformities) and reconstructive (for congenital or acquired deformities) surgery were compared with those in a general population sample.A group of 184 adolescent plastic surgery patients (corrective, n = 100; reconstructive, n = 84), and a comparison group of 83 adolescents at random selected from three municipalities (corrective, n = 67; reconstructive, n = 16), aged 12 to 22 years, were studied at two time points with a 6-month interval. The plastic surgical patients were studied presurgically and postsurgically. Using fully structured telephone interviews and postal questionnaires, adolescents' ratings of their appearance, bodily satisfaction and attitudes, and appearance-related burdens were obtained.All patients reported a significant decrease in burdens after surgery compared with the comparison group, indicating a much more prominent improvement in the patient sample compared with the developmental changes that may be expected to occur in adolescence. The corrective patient group reported least burdens after the operation. More specifically, the "breasts" group benefited most from the operation, indicating that breast corrections are rewarding interventions.The findings of this study imply that adolescents can be regarded as good candidates for plastic surgery. They gain bodily satisfaction, and they are relieved of many appearance-related burdens. Physical, social, and psychological burdens related to appearance satisfaction improve considerably in both corrective and reconstructive adolescent patients.