Figure-ground responsive fields of monkey V4 neurons estimated from natural image patches

Neurons in visual area V4 modulate their responses depending on the figure-ground (FG) organization in natural images containing a variety of shapes and textures. To clarify whether the responses depend on the extents of the figure and ground regions in and around the classical receptive fields (CRFs) of the neurons, we estimated the spatial extent of local figure and ground regions that evoked FG-dependent responses (RF-FGs) in natural images and their variants. Specifically, we applied the framework of spike triggered averaging (STA) to the combinations of neural responses and human-marked segmentation images (FG labels) that represent the extents of the figure and ground regions in the corresponding natural image stimuli. FG labels were weighted by the spike counts in response to the corresponding stimuli and averaged over. The bias due to the nonuniformity of FG labels was compensated by subtracting the ensemble average of FG labels from the weighted average. Approximately 50% of the neurons showed effective RF-FGs, and a large number exhibited structures that were similar to those observed in virtual neurons with ideal FG-dependent responses. The structures of the RF-FGs exhibited a subregion responsive to a preferred side (figure or ground) around the CRF center and a subregion responsive to a non-preferred side in the surroundings. The extents of the subregions responsive to figure were smaller than those responsive to ground in agreement with the Gestalt rule. We also estimated RF-FG by an adaptive filtering (AF) method, which does not require spherical symmetry (whiteness) in stimuli. RF-FGs estimated by AF and STA exhibited similar structures, supporting the veridicality of the proposed STA. To estimate the contribution of nonlinear processing in addition to linear processing, we estimated nonlinear RF-FGs based on the framework of spike triggered covariance (STC). The analyses of the models based on STA and STC did not show inconsiderable contribution of nonlinearity, suggesting spatial variance of FG regions. The results lead to an understanding of the neural responses that underlie the segregation of figures and the construction of surfaces in intermediate-level visual areas.journal articl

Van der Waals density functional study of n -alkane adsorbed on metal surfaces

Hamamoto Y., Shimada T., Kimura T., et al. Van der Waals density functional study of n -alkane adsorbed on metal surfaces. Physical Review B 110, 075409 (2024); https://doi.org/10.1103/PhysRevB.110.075409.We present a comprehensive study of n-alkane adsorbed on metal surfaces using the van der Waals density functional (vdW-DF) method. This method outperforms the density functional theory calculations within the local density or generalized gradient approximation in terms of a better description of a wide range of physisorption systems. Especially, our results demonstrate that vdW-DFs with improved accuracy nicely predict the adsorption heights of n-alkanes on close-packed metal surfaces. We also show that the C-H stretching frequencies and infrared absorption spectra are useful for discriminating the competing adsorption structures. Detailed analyses of the properties of n-alkanes on metal surfaces, however, reveal some discrepancies with experimental results, suggesting that further improvement of vdW-DF or the application of a more sophisticated technique is necessary for a systematic description of the n-alkane-metal interfaces with higher accuracy

A case of microscopic low-grade appendiceal mucinous neoplasm complicated with appendicitis resected by reduced-port laparoscopic surgery

Appendicitis is a benign disease for which surgical treatment is widely provided. The complication of neoplastic lesions may be discovered only after resection. However, in some cases, specimens are not submitted to histopathological examination in Japan because of an extreme deficiency of pathologists. We report our experience with one patient who experienced the complication of latent low-grade appendiceal mucinous neoplasm (LAMN) after surgery for appendicitis. Our patient was an 85-year-old woman. Conservative treatment failed to relieve fever and lower abdominal pain and it was decided to treat her surgically. Abdominal computed tomography (CT) showed appendicitis with severe inflammation and suspected adhesion. We decided to explore the abdominal cavity using a reduced-port laparoscopic approach. We found no mucous debouchment or clear tumors in the specimen. Histopathological findings indicated the coexistence of appendicitis and LAMN. At one year and a half after surgery, there was no evidence of the development of pseudomyxoma peritonei. In appendectomy, it is thought that careful perioperative treatment and a postoperative pathological search are important when there are no preoperative findings suggesting a neoplastic lesion

Population-level transition of capsular polysaccharide types among sequence type 1 group B Streptococcus isolates with reduced penicillin susceptibility during a long-term hospital epidemic

Over a 35-month period, group B Streptococcus isolates with reduced penicillin susceptibility (PRGBS) were detected from elderly patients at a regional hospital in Japan, accompanying population-level transition of PRGBS serotypes. The genetic relatedness of 77 non-duplicate PRGBS from 73 patients was analysed. Serotype III PRGBS predominated (16 serotype III/1 serotype Ib) in the first 9 months (period I), then 3 serotype Ib isolates appeared transiently for the next 3 months (period II), which was replaced predominantly by serotype Ia (20 serotype Ia/1 serotype III/1 non-typeable) for 9 months (period III). In the last 14 months (period IV), besides 25 serotype Ia isolates, 10 serotype III were also identified. Serotypes III and Ia isolates, belonging to ST1, shared G329V, G398A, V405A and G429D substitutions in penicillin-binding protein 2X. Of three strains subjected to whole-genome sequencing, serotype III strain SU12 (period I) had a higher degree of genomic similarity with serotype Ia strain SU97 (period III) than serotype Ib strain SU67 (period II) based on average nucleotide identity and single nucleotide polymorphisms. Analysis of the cps gene clusters and the upstream and downstream flanking sequences revealed that disruption of the hyaluronidase gene located upstream of cpsY by insertion of IS 1548 was found in strain SU12, whereas Delta ISSag8 was inserted between tRNA-Arg and rpsA genes located downstream of cpsL in strain SU97. Interestingly, most serotype III PRGBS re-emerging in period IV had this tRNA-Arg-Delta ISSag8-rpsA region. Capsular switching and nosocomial transmission may possibly contribute to population-level serotype replacement among ST1 PRGBS isolates. (c) 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.ArticleINTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS.53(3):203-210(2019)journal articl