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Thesis advisor: Elizabeth A. Kensinger / Emotion enhances memory longevity and vividness. Perceiving an experience as emotional, as well as the autonomic and functional brain responses involved in initially encoding an emotional experience, have been theorized to “tag” these memories. Tagged memories may then be prioritized for consolidation during sleep. However, direct evidence supporting this theory is sparse. The aim of the present study was to determine which encoding-related indicators of memory tagging interact with post-encoding sleep oscillations to promote emotional memory retention and vividness. To test this, participants incidentally encoded positive, neutral and negative multisensory stimuli during 3T fMRI scanning with concurrent heart rate monitoring. Participants provided emotional intensity ratings after each stimulus presentation. Following a 120-min post-encoding nap opportunity recorded with polysomnography, participants completed a surprise memory test. Memory for emotional and neutral stimuli was equivalent, though emotional stimuli tended to be remembered more vividly. Perceived emotional intensity, but not heart rate deceleration (HRD) magnitude or functional brain activity, was diagnostic of later successful retrieval of emotional, but not neutral stimuli. Higher REM sleep theta power during the nap was associated with a greater emotional intensity (EI) subsequent memory effect (i.e., higher EI for later remembered compared to forgotten stimuli) for positive stimuli, which were also remembered more vividly. Higher NREM spindle density was associated with a greater EI subsequent memory effect for neutral stimuli and lesser EI subsequent memory effect for negative stimuli. Lastly, higher numbers of NREM spindle-slow oscillation coupling events predicted a negative relationship between perceived emotional intensity at encoding and memory vividness for negative stimuli. Taken together, the present findings suggest that subjective, rather than objective, encoding-related arousal responses acted as emotion “tags”. How subjective arousal impacted later memory varied as a function of the memory’s emotion category and REM and NREM-specific oscillations. Future work is needed to clarify the underlying mechanisms for these observed effects. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

Over the years emojis have become a fundamental and natural part in online based communication. Due to this emojis have also entered the judicial system by appearing in several court cases, used as evidence for or against intent to commit crime. This essay studies relevant cases presented in Swedish trials to better understand how emojis are interpreted and processed within Swedish law. Additional interviews help to further examine possible approaches for a more trustworthy emoji-interpretation by the judicial system. The essays main findings further indicate that emojis are complex when used as evidence. This due to their ambiguity as well as not yet being an established part in court cases - furthermore complicating the judicial process of decoding these symbols. In addition, the essay finds that emojis' meanings are largely tied to culture and are also often platform-based. In order to avoid misunderstandings and wrongful decoding from litigators, this essays results proposes two main solutions: (1) organizations such as Unicode, as well as different platforms, should have a greater responsibility when technically standardizing emojis, to reduce misunderstandings. (2) Courts should at a higher rate introduce experts, such as linguists or emoji-experts, to ensure that emojis are decoded in a proper way.

In producing a user interface design to visualize search results for a digital library called Envision [Nowell, France, Hix, Heath, &amp; Fox, 1996] [Fox, Hix, Nowell, et al., 1993] [Nowell &amp; Hix, 1993], we found that choosing graphical devices and document attributes to be encoded with each graphical device is a surprisingly difficult task. By <i>graphical devices</i> we mean those visual display elements (e.g., color, shape, size, position, etc.) used to convey encoded, semantic information. Research in the areas of psychophysics of visual search and identification tasks, graphical perception, and graphical language development provides scientific guidance for design and evaluation of graphical encodings which might otherwise be reduced to opinion and personal taste. However, literature offers inconclusive and often conflicting viewpoints, suggesting a need for further research. The goal of this research was to determine empirically the effectiveness of graphical devices for encoding nominal and quantitative information in complex visualization displays. Using the Envision Graphic View, we conducted a within-subjects empirical investigation of the effectiveness of three graphical devices - <i>icon color, icon shape,</i> and <i>icon size</i> - in communicating nominal (document type) and quantitative (document relevance) data. Our study provides empirical evidence regarding the relative effectiveness of icon color, shape, and size for conveying both nominal and quantitative data. While our studies consistently rank color as most effective, the rankings differ for shape and size. For nominal data, icon shape ranks ahead of icon size by all measures except time for task completion, which places shape behind size. For quantitative data, we found, by all measures, that encodings with icon shape are more effective than with icon size. We conclude that the <i>nature of tasks</i> performed and the relative <i>importance of measures of effectiveness</i> are more significant than the type of data represented for designers choosing among rankings. / Ph. D.

The wake human brain constantly samples perceptual information from the environment and integrates them into existing neuronal networks. Neuronal oscillations have been ascribed a key role in the formation of novel memories. The theta rhythm (3-8 Hz) reflects a central executive mechanism, which integrates novel information, reflected in theta-coupled gamma oscillations (> 30 Hz). Alpha oscillations (8-14 Hz) reflect an attentional gating mechanism, which inhibit task irrelevant neuronal processes. In my dissertation I further scrutinized the oscillatory dynamics of memory formation. Study 1 demonstrated that theta-gamma coupling reflects a specific mechanism for associative memory formation. In study 2, I experimentally entrained memory encoding by visual evoked theta-gamma coupling processes, to underline its functional relevance. In two developmental studies, I found that the theta rhythm indexes explicit learning processes in adults and young children (study 3), and that visually entrained theta oscillations are sensitive to the encoding of novel, unexpected events, already in the first year of life (study 4). Throughout these studies alpha oscillations were not sensitive to memory formation processes, but indicated perceptual (study 1) and semantic (study 3) processes. I propose an integrative framework, suggesting that the alpha rhythm reflects activated semantic representations in the neocortex, while theta-gamma coupling reflects an explicit mnemonic control mechanism, which selects, elaborates and integrates activated representations. Specifically, by squeezing real time events onto a faster, neuronal time scale, theta-gamma coding facilitates neuronal plasticity in medio-temporal networks and advances neuronal processes ahead of real time to emulate and guide future behavior.

Computational models combined with electrophysiological studies have informed our understanding about the role of hippocampal subfields (dentate gyrus, DG; CA subfields, subiculum) and Medial Temporal Lobe (MTL) cortex (entorhinal, perirhinal, parahippocampal cortices) during working memory (WM) tasks. Only recently have functional neuroimaging studies begun to examine under which conditions the MTL are recruited for WM processing in humans, but subfield contributions have not been examined in the WM context. High-resolution fMRI is well suited to test hypotheses regarding the recruitment of MTL subregions and hippocampal subfields. This dissertation describes three experiments using high-resolution fMRI to examine the role of hippocampal subfields and MTL structures in humans during WM. Experiment 1 investigated MTL activity when participants performed a task that required encoding and maintaining overlapping and non-overlapping stimulus pairs during WM. During encoding, activity in CA3/DG and CA1 was greater for stimulus pairs with overlapping features. During delay, activity in CA1 and entorhinal cortex was greater for overlapping stimuli. These results indicate that CA3/DG and CA1 support disambiguating overlapping representations while CA1 and entorhinal cortex maintain these overlapping items. Experiment 2 investigated MTL activity when participants performed a WM task that required encoding and maintaining either low or high WM loads. The results show a load effect in entorhinal and perirhinal cortex during the delay period and suggest that these regions act as a buffer for WM by actively maintaining novel information in a capacity-dependent manner. Experiment 3 investigated MTL activity when participants performed a WM task that required maintaining similar and dissimilar items at different loads. Analysis of a load by similarity interaction effect revealed areas of activity localized to the CA1 subfield. CA1 showed greater activity for higher WM loads for dissimilar, but not similar stimuli. Our findings help identify hippocampal and MTL regions that contribute to disambiguation in a WM context and regions that are active in a capacity-dependent manner which may support long-term memory formation. These results help inform our understanding of the contributions of hippocampal subfields and MTL subregions during WM and help translate findings from animal work to the cognitive domain of WM in humans.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第19111号 / 情博第557号 / 新制||情||98(附属図書館) / 32062 / 京都大学大学院情報学研究科知能情報学専攻 / (主査)教授 松山 隆司, 教授 美濃 導彦, 准教授 梁 雪峰 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Shrinking minimum feature size in deep sub-micron has made fabrication of progressively faster devices possible. The performance of interconnects has been a bottleneck in determining the overall performance of a chip. A reliable high-speed communication technique is necessary to improve the performance of on-chip communication. Recent publications have demonstrated that use of multiple threshold voltages improves the performance of a bus significantly. The multi-threshold capture mechanism takes advantage of predictable temporal behavior of a tightly coupled bus to predict the next state of the bus early. However, Use of multiple threshold voltages also reduces the voltage slack and consequently increases the susceptibility to noise. Reduction in supply voltage exacerbates the situation. This work proposes a novel error detection and correction encoding technique that takes advantage of the high performance of the multi-threshold capture mechanism as well as its inbuilt redundancy to achieve reliable high-speed communication while introducing considerably less amount of redundancy as compared to the conventional methods. The proposed technique utilizes graph-based algorithms to produce a set of valid code words. The algorithm takes advantage of implicit set operations using binary decision diagram to improve the scalability of the code word selection process. The code words of many crosstalk avoidance codes including the proposed error detection and correction technique exhibit a highly structured behavior. The sets of larger valid code words can be recursively formed using the sets of smaller valid code words. This work also presents a generalized framework for scalable on-chip code word generation. The proposed CODEC implementation strategy uses a structured graph to model the recursive nature of an encoding technique that facilitates scalable CODEC implementation. The non-enumerative nature of the implementation strategy makes it highly scalable. The modular nature of the CODEC also simplifies use of pipelined architecture thereby improving the throughput of the bus.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / During the life cycle of enteric bacterium Escherichia coli, it encounters a wide spectrum of pH changes. The asymmetric dimer of the cAMP receptor protein, CRP, plays a key role in regulating the expressions of genes and the survival of E. coli. To elucidate the pH effects on the mechanism of signal transmission, we present a combination of results derived from ITC, crystallography, and computation. CRP responds to a pH change by inducing a differential effect on the affinity for the binding events to the two cAMP molecules, ensuing in a reversible conversion between positive and negative cooperativity at high and low pH, respectively. The structures of four crystals at pH ranging from 7.8 to 6.5 show that CRP responds by inducing a differential effect on the structures of the two subunits, particularly in the DNA binding domain. Employing the COREX/BEST algorithm, computational analysis shows the change in the stability of residues at each pH. The change in residue stability alters the connectivity between residues including those in cAMP and DNA binding sites. Consequently, the differential impact on the topology of the connectivity surface among residues in adjacent subunits is the main reason for differential change in affinity; that is, the pH-induced differential change in residue stability is the biothermodynamic basis for the change in allosteric behavior. Furthermore, the structural asymmetry of this homodimer amplifies the differential impact of any perturbations. Hence, these results demonstrate that the combination of these approaches can provide insights into the underlying mechanism of an apparent complex allostery signal and transmission in CRP. / National Institutes of Health / Revisión por pares

<P> For over six decades, the theory and design of radar systems have been dominated by probability theory and statistics, information theory, signal processing and control. However, the similar encoding-decoding property that exists between the visual brain and radar has been sadly overlooked in all radar systems. This thesis lays down the foundation of a new generation of radar systems, namely cognitive radar, that was described in a 2006 seminal paper by Haykin. Four essential elements of cognitive radar are Bayesian filtering in the receiver, dynamic programming in the transmitter, memory, and global feedback to facilitate computational intelligence. All these elements excluding the memory compose a well known property of mammalian cortex, the perception-action cycle. As such, the cognitive radar that has only this cycle is named as the basic cognitive radar (BCR). For t racking applications, t his thesis presents the underlying theory of BCR, with emphasis being placed on the cubature Kalman filter to approximate the Bayesian filter in the receiver, dynamic optimization for transmit-waveform selection in the transmitter, and global feedback embodying the transmitter , the radar environment, and the receiver all under one overall feedback loop. </p> <p> Built on the knowledge learnt from the BCR, this thesis expands the basic perception-action cycle to encompass three more properties of human cognition , that is, memory, attention, and intelligence. Specifically, the provision for memory includes the three essential elements, i. e. , the perceptual memory, executive memory, and coordinating perception-action memory that couples the first two memories. Provision of the three memories adds an advanced version of cognitive radar, namely the nested cognitive radar (NCR) in light of the nesting of three memories in the perception-action cycle. </p> <p> In this thesis, extensive computer simulations are also conducted to demonstrate the ability of this new radar concept over a conventional radar structure. Three important scenarios of tracking applications are considered, they are (a), linear target tracking; (b), falling object tracking; and (c), high-dimensional target tracking with continuous-discrete model. All simulation results confirm that cognitive radar outperforms the conventional radar systems significantly. </p> <p> In conducting the simulations, an interesting phenomenon is also observed, which is named the chattering effect. The underlying physics and mathematical model of this effect are discussed. For the purpose of studying the behaviour of cognitive radar in disturbance, demonstrative experiments are further conducted. Simulation results indicate the superiority of NCR over BCR and t he conventional radar in low, moderate and even strong disturbance. </p> / Thesis / Doctor of Philosophy (PhD)