The roles of the "ventral" semantic and "dorsal" pathways in conduite d'approche: A neuroanatomically-constrained computational modeling investigation

Ever since the 19th century, the standard model for spoken language processing has assumed two pathways for repetition—a phonological pathway and a semantic pathway—and this idea has gained further support in the last decade. First, recent in vivo tractography studies have demonstrated both the “dorsal” (via arcuate fasciculus) and “ventral” (via extreme capsule and uncinate fasciculus) pathways connecting from the primary auditory area to the speech-motor area, the latter of which passes through a brain area associated with semantic processing (anterior temporal lobe). Secondly, neuropsychological evidence for the role of semantics in repetition is conduite d'approche, a successive phonological improvement (sometimes non-improvement) in aphasic patients' response by repeating several times in succession. Crucially, conduite d'approche is observed in patients with neurological damage in/around the arcuate fasciculus. Successful conduite d'approche is especially clear for semantically-intact patients and it occurs for real words rather than for non-words. These features have led researchers to hypothesize that the patients' disrupted phonological output is “cleaned-up” by intact lexical-semantic information before the next repetition. We tested this hypothesis using the neuroanatomically-constrained dual dorsal-ventral pathway computational model. The results showed that (a) damage to the dorsal pathway impaired repetition; (b) in the context of recovery, the model learned to compute a correct repetition response following the model's own noisy speech output (i.e., successful conduite d'approche); (c) this behavior was more evident for real words than non-words; and (d) activation from the ventral pathway contributed to the increased rate of successful conduite d'approche for real words. These results suggest that lexical-semantic “clean-up” is key to this self-correcting mechanism, supporting the classic proposal of two pathways for repetition

The PCI Interface for GRAPE Systems: PCI-HIB

We developed a PCI interface for GRAPE systems. GRAPE(GRAvity piPE) is a special-purpose computer for gravitational N-body simulations. A GRAPE system consists of GRAPE processor boards and a host computer. GRAPE processors perform the calculation of gravitational forces between particles. The host computer performs the rest of calculations. The newest of GRAPE machines, the GRAPE-4, achieved the peak performance of 1.08 Tflops. The GRAPE-4 system uses TURBOChannel for the interface to the host, which limits the selection of the host computer. The TURBOChannel bus is not supported by any of recent workstations. We developed a new host interface board which adopts the PCI bus instead of the TURBOChannel. PCI is an I/O bus standard developed by Intel. It has fairly high peak transfer speed, and is available on wide range of computers, from PCs to supercomputers. Thus, the new interface allows us to connect GRAPE-4 to a wide variety of host computers. In test runs with a Barnes-Hut treecode, we found that the performance of new system with PCI interface is 40% better than that of the original system.Comment: 15 pages, 10 Postscript figures, 3 tables, Latex, submitted to Publications of the Astronomical Society of Japan. corrected figure 2 which contained non standard font

Effects of Dietary Lysine Levels on the Plasma Concentrations of Growth‐Related Hormones in Late‐Stage Finishing Pigs

This study was undertaken to investigate the effects of dietary lysine on the plasma concentrations of three growth‐related hormones in pigs. Nine late‐stage finishing barrows were assigned to three dietary treatments according to a completely randomized experimental design (3 pigs/treatment). Three corn and soybean meal‐based diets were formulated to contain three levels of lysine, which were 0.43, 0.71, and 0.98% for Diets 1 (lysine deficient), 2 (lysine adequate), and 3 (lysine excess), respectively. The feeding trial lasted 4 weeks, during which the pigs were allowed ad libitum access to the diets and water. After the 4 weeks, blood was collected and plasma samples were obtained. Then, the plasma concentrations of insulin, growth hormone (GH), and insulin‐like growth factor 1 (IGF‐1) were measured. No difference in the plasma concentration of insulin or GH among the three treatments was found (P > 0.10). However, the plasma IGF‐1 concentration was lower (P < 0.05) in the pigs fed Diet 1 or 3 than fed Diet 2, suggesting that either dietary lysine deficiency or excess can lead to a lower concentration of plasma IGF‐1. It was concluded that IGF‐1, instead of insulin or GH, in the blood may be a key controlling growth factor in response to dietary lysine supply for regulating muscle growth in late‐stage finishing pigs

Increased Neutrophil Extracellular Trap-Mediated Staphylococcus aureus Clearance Through Inhibition of Nuclease Activity by Clindamycin and Immunoglobulin

The Gram-positive human pathogen Staphylococcus aureus causes a variety of human diseases such as skin infections, pneumonia, and endocarditis. The micrococcal nuclease Nuc1 is one of the major S. aureus virulence factors and allows the bacterium to avoid neutrophil extracellular trap (NET)-mediated killing. We found that addition of the protein synthesis inhibitor clindamycin to S. aureus LAC cultures decreased nuc1 transcription and subsequently blunted nuclease activity in a molecular beacon-based fluorescence assay. We also observed reduced NET degradation through Nuc1 inhibition translating into increased NET-mediated clearance. Similarly, pooled human immunoglobulin specifically inhibited nuclease activity in a concentration-dependent manner. Inhibition of nuclease activity by clindamycin and immunoglobulin enhanced S. aureus clearance and should be considered in the treatment of S. aureus infection

Trends in life science grid: from computing grid to knowledge grid

BACKGROUND: Grid computing has great potential to become a standard cyberinfrastructure for life sciences which often require high-performance computing and large data handling which exceeds the computing capacity of a single institution. RESULTS: This survey reviews the latest grid technologies from the viewpoints of computing grid, data grid and knowledge grid. Computing grid technologies have been matured enough to solve high-throughput real-world life scientific problems. Data grid technologies are strong candidates for realizing "resourceome" for bioinformatics. Knowledge grids should be designed not only from sharing explicit knowledge on computers but also from community formulation for sharing tacit knowledge among a community. CONCLUSION: Extending the concept of grid from computing grid to knowledge grid, it is possible to make use of a grid as not only sharable computing resources, but also as time and place in which people work together, create knowledge, and share knowledge and experiences in a community

Direct exploration of the role of the ventral anterior temporal lobe in semantic memory:Cortical stimulation and local field potential evidence from subdural grid electrodes

Semantic memory is a crucial higher cortical function that codes the meaning of objects and words, and when impaired after neurological damage, patients are left with significant disability. Investigations of semantic dementia have implicated the anterior temporal lobe (ATL) region, in general, as crucial for multimodal semantic memory. The potentially crucial role of the ventral ATL subregion has been emphasized by recent functional neuroimaging studies, but the necessity of this precise area has not been selectively tested. The implantation of subdural electrode grids over this subregion, for the presurgical assessment of patients with partial epilepsy or brain tumor, offers the dual yet rare opportunities to record cortical local field potentials while participants complete semantic tasks and to stimulate the functionally identified regions in the same participants to evaluate the necessity of these areas in semantic processing. Across 6 patients, and utilizing a variety of semantic assessments, we evaluated and confirmed that the anterior fusiform/inferior temporal gyrus is crucial in multimodal, receptive, and expressive, semantic processing