7 research outputs found
Characterization of patients with major psychiatric disorders with AMPA receptor positron emission tomography
Get PDFSynaptic phenotypes in living patients with psychiatric disorders are poorly characterized. Excitatory glutamate α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) is a fundamental component for neurotransmission. We recently developed a positron emission tomography (PET) tracer for AMPAR, [11C]K-2, the first technology to visualize and quantify AMPARs density in living human brain. In this study, we characterized patients with major psychiatric disorders with [11C]K-2. One hundred forty-nine patients with psychiatric disorders (schizophrenia, n = 42; bipolar disorder, n = 37; depression, n = 35; and autism spectrum disorder, n = 35) and 70 healthy participants underwent a PET scan with [11C]K-2 for measurement of AMPAR density. We detected brain regions that showed correlation between AMPAR density and symptomatology scores in each of four disorders. We also found brain areas with significant differences in AMPAR density between patients with each psychiatric disorder and healthy participants. Some of these areas were observed across diseases, indicating that these are commonly affected areas throughout psychiatric disorders. Schizophrenia, bipolar disorder, depression, and autism spectrum disorder are uniquely characterized by AMPAR distribution patterns. Our approach to psychiatric disorders using [11C]K-2 can elucidate the biological mechanisms across diseases and pave the way to develop novel diagnostics and therapeutics based on the synapse physiology
Contributions of temporal envelope and temporal fine structure to segregation of Lombard speech from background noise
Get PDFLombard speech is known to make it easier for listeners to perceive speech signals in the presence of background noise. The aim of this study was to investigate how temporal characteristics such as the temporal envelope and temporal fine structure (TFS) in Lombard speech contribute to improve the segregation of Lombard speech from background noises. In the speech production task, we confirmed that Lombard speech had increased low-frequency amplitude modulations in the temporal envelope and increased frequency modulations in TFS compared to plain speech in frequency ranges covering first and second formants. In a speech perception task, ease of speech segregation was compared between Lombard and plain speech. We also compared ease of segregation of tone-vocoded speech created from Lombard and plain speech to examine the effect of eliminating TFS. We found that Lombard speech with both high amplitude and frequency modulations had improved speech segregation in both original and tone-vocoded speech conditions, but the difference in ease of speech segregation between Lombard and plain speech tended to be larger in original speech than tone-vocoded speech conditions. The present findings suggest that an enhanced envelope is the main contributor to improved segregation of Lombard speech, while increased frequency modulation plays a complementary role.Citation: Shunsuke Tamura, Mitsunori Mizumachi, Contributions of temporal envelope and temporal fine structure to segregation of Lombard speech from background noise. Acoustical Science and Technology. 2024-01-01, 45(1), 33-44, https://doi.org/10.1250/ast.e23.2
Simplified Method for Estimation of Microbial Activity in Compost by ATP Analysis
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Direct Monte Carlo Calculation on Heat Transfer through a Rarefied Gas
No full textapplication/pdfThe direct simulation Monte Carlo method is used for analysis of a heat transfar from a spine-fin through a rarefied gas. The heat flux which flows from a base of the spine through its cross-section is transferred from a surface of the spine by molecular motion and radiation. Two types of time scale are required ; one is for the molecular motion and the other is for appreciable change of the spine temperature. Since the latter time scale is several orders larger than the former, a weighting factor of the time scale is used to compensate for the large time disparities. The results of the calculation are compared with those of experiment.departmental bulletin pape
