Mental images in episodic memory

Episodic memory, i.e. memorization of information within a spatiotemporal environment, is affected by Alzheimer's disease (AD) but its loss may also occur in the normal aging process. The purpose of this study is to analyze and evaluate episodic memory in patients with AD by examining their cognitive skills in episodic memory through the introspection technique. A new method was used, wherein we assessed mental images of the subject's own past recalled in the mind like projected pictures and movies. Experiment 1 is designed to determine the effect and process of normal and pathological aging on cognitive skills in episodic memory using the introspection technique. Two groups were observed towards this purpose: 21 patients with AD and 19 normal control subjects. All subjects were chosen from ages from 55 to 70 and were administered standardized neuropsychological tests (K-DRS and MMSE-K). All subjects were asked to retrieve their episodic memory of the previous day, week, month, and a day remote from testing day. The answers were analyzed, focusing on their specific features such as emotional state, color, and time order. In the following day, the subjects were tasked to recall again all images that they reproduced in the previous day's test in order to observe impairment of anterograde memory. Results showed that patients failed to arrange the retrieved images in time order and their images of the previous day were unclear in color and were stationary like photographs, even when they reproduced the mental images at as much quantity as controls. They also could not remember particular events of yesterday, only their general occurrence. These results suggest that in the early stage of AD, difficulties in the retrieval of recent episodic memory begin to occur, and qualitative impairment happens earlier than quantitative. The third chapter supports these results with further evidence, analyzing from a clinical viewpoint 3 patients with AD, 1 patient with mild depression and 2 controls. In Experiment 2 the emotional intensity of episodic memory within different categories of memory (yesterday, week, month, and remote) was investigated by comparing healthy elderly people and AD patients. The subjects’ voice intonations were estimated by 8 valuators. As a result, the emotional intensity of AD patient was evaluated lower than controls. It appears that patients in the early stage of AD are impaired in the ability to express emotions during emotional episodic memory retrieval compared to healthy elderly adults

Mental images in episodic memory

Episodic memory, i.e. memorization of information within a spatiotemporal environment, is affected by Alzheimer's disease (AD) but its loss may also occur in the normal aging process. The purpose of this study is to analyze and evaluate episodic memory in patients with AD by examining their cognitive skills in episodic memory through the introspection technique. A new method was used, wherein we assessed mental images of the subject's own past recalled in the mind like projected pictures and movies. Experiment 1 is designed to determine the effect and process of normal and pathological aging on cognitive skills in episodic memory using the introspection technique. Two groups were observed towards this purpose: 21 patients with AD and 19 normal control subjects. All subjects were chosen from ages from 55 to 70 and were administered standardized neuropsychological tests (K-DRS and MMSE-K). All subjects were asked to retrieve their episodic memory of the previous day, week, month, and a day remote from testing day. The answers were analyzed, focusing on their specific features such as emotional state, color, and time order. In the following day, the subjects were tasked to recall again all images that they reproduced in the previous day's test in order to observe impairment of anterograde memory. Results showed that patients failed to arrange the retrieved images in time order and their images of the previous day were unclear in color and were stationary like photographs, even when they reproduced the mental images at as much quantity as controls. They also could not remember particular events of yesterday, only their general occurrence. These results suggest that in the early stage of AD, difficulties in the retrieval of recent episodic memory begin to occur, and qualitative impairment happens earlier than quantitative. The third chapter supports these results with further evidence, analyzing from a clinical viewpoint 3 patients with AD, 1 patient with mild depression and 2 controls. In Experiment 2 the emotional intensity of episodic memory within different categories of memory (yesterday, week, month, and remote) was investigated by comparing healthy elderly people and AD patients. The subjects’ voice intonations were estimated by 8 valuators. As a result, the emotional intensity of AD patient was evaluated lower than controls. It appears that patients in the early stage of AD are impaired in the ability to express emotions during emotional episodic memory retrieval compared to healthy elderly adults

Bound-state-in-continuum guided modes in a multilayer electro-optically active photonic integrated circuit platform

Bound states in the continuum (BICs) are localized states existing within a continuous spectrum of delocalized waves. Emerging multilayer photonic integrated circuit (PIC) platforms allow implementation of low index 1D guided modes within a high-index 2D slab mode continuum; however, conventional wisdom suggests that this always leads to large radiation losses. Here we demonstrate low-loss BIC guided modes for multiple mode polarizations and spatial orders in single- and multi-ridge low-index waveguides within a two-layer heterogeneously integrated electro-optically active photonic platform. The transverse electric (TE) polarized quasi-BIC guided mode with low, <1.4 dB/cm loss enables a Mach-Zehnder electro-optic amplitude modulator comprising a single straight Si3N4 ridge waveguide integrated with a continuous LiNbO3 slab layer. The abrupt optical transitions at the edges of the slab function as compact and efficient directional couplers eliminating the need for additional components. The modulator exhibits a low insertion loss of 2.3 dB and a high extinction ratio of 25 dB. The developed general theoretical model may enable innovative BIC-based approaches for important PIC functions, such as agile spectral filtering and switching, and may suggest new photonic architectures for quantum and neural network applications based on controlled interactions between multiple guided and delocalized modes

Agile chip-scale electro-optic frequency comb spectrometer with millivolt drive voltages

Here, we present an on-chip spectrometer that leverages an integrated thin-film lithium niobate modulator to produce a frequency-agile electro-optic frequency comb for interrogating chip-scale temperature and acceleration sensors. The low half-wave voltage, $V_{\pi}$, of the modulators and the chirped comb process allows for ultralow radiofrequency drive voltages, which are as much as seven orders of magnitude less than the lowest found in the literature and are generated using a chip-scale, microcontroller-driven direct digital synthesizer. The on-chip comb spectrometer is able to simultaneously interrogate both the on-chip temperature sensor and an off-chip, microfabricated optomechanical accelerometer with cutting-edge sensitivities of $\approx 5 {\mu} \mathrm{K} \cdot \mathrm{Hz} ^{-1/2}$ and $\approx 130 {\mu}\mathrm{m} \cdot \mathrm{s}^{-2} \cdot \mathrm{Hz}^{-1/2}$, respectively. Notable strengths of this platform include the frequency agility of the optical frequency combs, ultralow radiofrequency power requirements and compatibility with a broad range of existing photonic integrated circuit technologies.Comment: 11 pages, 5 figure

A Putative Transcription Factor MYT1 Is Required for Female Fertility in the Ascomycete Gibberella zeae

Gibberella zeae is an important pathogen of major cereal crops. The fungus produces ascospores that forcibly discharge from mature fruiting bodies, which serve as the primary inocula for disease epidemics. In this study, we characterized an insertional mutant Z39P105 with a defect in sexual development and identified a gene encoding a putative transcription factor designated as MYT1. This gene contains a Myb DNA-binding domain and is conserved in the subphylum Pezizomycotina of Ascomycota. The MYT1 protein fused with green fluorescence protein localized in nuclei, which supports its role as a transcriptional regulator. The MYT1 deletion mutant showed similar phenotypes to the wild-type strain in vegetative growth, conidia production and germination, virulence, and mycotoxin production, but had defect in female fertility. A mutant overexpressing MYT1 showed earlier germination, faster mycelia growth, and reduced mycotoxin production compared to the wild-type strain, suggesting that improper MYT1 expression affects the expression of genes involved in the cell cycle and secondary metabolite production. This study is the first to characterize a transcription factor containing a Myb DNA-binding domain that is specific to sexual development in G. zeae

A Putative Transcription Factor MYT2 Regulates Perithecium Size in the Ascomycete Gibberella zeae

The homothallic ascomycete fungus Gibberella zeae is a plant pathogen that is found worldwide, causing Fusarium head blight (FHB) in cereal crops and ear rot of maize. Ascospores formed in fruiting bodies (i.e., perithecia) are hypothesized to be the primary inocula for FHB disease. Perithecium development is a complex cellular differentiation process controlled by many developmentally regulated genes. In this study, we selected a previously reported putative transcription factor containing the Myb DNA-binding domain MYT2 for an in-depth study on sexual development. The deletion of MYT2 resulted in a larger perithecium, while its overexpression resulted in a smaller perithecium when compared to the wild-type strain. These data suggest that MYT2 regulates perithecium size differentiation. MYT2 overexpression affected pleiotropic phenotypes including vegetative growth, conidia production, virulence, and mycotoxin production. Nuclear localization of the MYT2 protein supports its role as a transcriptional regulator. Transcriptional analyses of trichothecene synthetic genes suggest that MYT2 additionally functions as a suppressor for trichothecene production. This is the first study characterizing a transcription factor required for perithecium size differentiation in G. zeae, and it provides a novel angle for understanding sexual development in filamentous fungi

Efficient On-chip Optical Microresonator for Optical Comb Generation: Design and Fabrication

An optical frequency comb is a series of equally spaced frequency components. It has gained much attention since Nobel physics prize was awarded John L. Hall and Theodor W. Hänsch for their contribution to the optical frequency comb technique in 2005. The optical frequency comb has been extensively studied because of its precision as a tool for spectroscopy, and is now widely used in bio- and chemical sensors, optical clocks, mode-locked dark pulse generation, soliton generation, and optical communication. Recently, thanks to the developments in nanotechnology, the optical frequency comb generation is made possible at a chip-scale level with microresonators. However, because the threshold power of the optical frequency comb generation is beyond the capability of the on-chip laser source, efficient microresonator is required. Here, we demonstrate an ultra-compact and highly efficient strip-slot direct mode coupler, aiming to achieve slotted silicon microresonator cladded with nonlinear polymer Poly-DDMEBT in SOI platform. As an application of the strip-slot direct mode coupling, a double slot fiber-to-chip edge coupler is demonstrated showing 2 dB insertion loss reduction compared to the conventional single tip edge coupler. For silicon nitride platform, we investigated evanescent wave coupling of microresonator, focusing on bus waveguide geometry optimization. The optimized waveguide width offers an efficient excitation of a fundamental mode in the resonator waveguide. This investigation can benefit low threshold comb generation by enhancing the extinction ratio. We experimentally demonstrated the high Q-factor micro-ring resonator with intrinsic Q of 12.6 million as well as the single FSR comb generation with 63 mW