Sub-Millisecond Firing Synchrony of Closely Neighboring Pyramidal Neurons in Hippocampal CA1 of Rats During Delayed Non-Matching to Sample Task

Firing synchrony among neurons is thought to play functional roles in several brain regions. In theoretical analyses, firing synchrony among neurons within sub-millisecond precision is feasible to convey information. However, little is known about the occurrence and the functional significance of the sub-millisecond synchrony among closely neighboring neurons in the brain of behaving animals because of a technical issue: spikes simultaneously generated from closely neighboring neurons are overlapped in the extracellular space and are not easily separated. As described herein, using a unique spike sorting technique based on independent component analysis together with extracellular 12-channel multi-electrodes (dodecatrodes), we separated such overlapping spikes and investigated the firing synchrony among closely neighboring pyramidal neurons in the hippocampal CA1 of rats during a delayed non-matching to sample task. Results showed that closely neighboring pyramidal neurons in the hippocampal CA1 can co-fire with sub-millisecond precision. The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison) and external (stimulus input and motor output) events during the task. However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently. We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information – as represented by the firing rate modulations – to downstream neurons

Le Japon dans l'ordre mondial. Une position perpétuellement précaire

Les dirigeants du Japon de Meiji partageaient une vision « réaliste » de l'ordre du monde. Le but de la politique extérieure était de s'élever par la force dans la hiérarchie des nations. Mais en tant que « colonie informelle » des puissances occidentales (jusqu'en 1905), puis de « puissance régionale », le Japon ne pouvait pas s'assurer une position internationale stable. Il était pris entre son incapacité à légitimer son expansion vis-à-vis de ses « inférieurs » des autres pays asiatiques) et le contrôle exercé par ses « supérieurs » (les grandes puissances mondiales). La brutalité et la frustration en ont découlé. Après 1945, son accoutumance au « réalisme » et à une pratique des relations internationales fondée sur l'usage de la force militaire a permis au Japon de trouver aisément sa place dans l'ordre de la guerre froide, en qualité de « puissance régionale subordonnée ». Il n'a pas su devenir, à l'instar de l'Allemagne, une « puissance moyenne ». Il en restera incapable aussi longtemps que la vision du monde de ses dirigeants ne changera pas.The leaders of Meiji Japan shared a "realistic" view of the world order. The purpose of foreign policy was to help Japan rise up in the hierarchy of nations through the use of force. But as an "informal colony" of the Western powers (until 1905), and then as a "regional power", Japan could not achieve a stable international position. It was caught between its inability to legitimize its expansion vis-à-vis its "inferiors" (the other Asian countries) and the control exercised by its "superiors" (the major world powers). The result was brutality and frustration. After 1945, Japan became used to "realism" and the conduct of international relations based on the use of military force, thus allowing it to find its place easily in the world order of the Cold War era, as a "subordinate regional power". It was never able to become, like Germany, a "middle power". It will remain unable to become one as long as the worldview of its leaders does not change

Cavity dumping of an injection-locked free-electron laser

This letter reports cavity dumping of an electrostatic-accelerator-driven free-electron laser (FEL) while it is injection-locked to a frequency-stabilized 240 GHz solid-state source. Cavity dumping enhances the FEL output power by a factor of $\sim$8, and abruptly cuts off the end of the FEL pulse. The cavity-dumped, injection-locked FEL output is used in a 240 GHz pulsed electron spin resonance (ESR) experiment.Comment: 8 pages including 3 figure

Demonstration of NV-detected ESR spectroscopy at 115 GHz and 4.2 Tesla

High frequency electron spin resonance (ESR) spectroscopy is an invaluable tool for identification and characterization of spin systems. Nanoscale ESR using the nitrogen-vacancy (NV) center has been demonstrated down to the level of a single spin. However, NV-detected ESR has exclusively been studied at low magnetic fields, where spectral overlap prevents clear identification of spectral features. Within this work, we demonstrate NV-detected ESR measurements of single-substitutional nitrogen impurities in diamond at a NV Larmor frequency of 115 GHz and the corresponding magnetic field of 4.2 Tesla. The NV-ESR measurements utilize a double electron-electron resonance sequence and are performed using both ensemble and single NV spin systems. In the single NV experiment, chirp pulses are used to improve the population transfer and for NV-ESR measurements. This work provides the basis for NV-based ESR measurements of external spins at high magnetic fields.Comment: 12 pages, 4 figure

1H-，17O-NMRによる水の液体構造解析に関する研究

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