A novel quality metric using spatiotemporal correlational data of human eye maneuver

The popularly used subjective estimator- mean opinion score (MOS) is often biased by the testing environment, viewers mode, domain expertise, and many other factors that may actively influence on actual assessment. We therefore, devise a no- reference subjective quality assessment metric by exploiting the nature of human eye browsing on videos. The participants' eye-tracker recorded gaze-data indicate more concentrated eye- traversing approach for relatively better quality. We calculate the Length, Angle, Pupil-size, and Gaze-duration features from the recorded gaze trajectory. The content and resolution invariant operation is carried out prior to synthesizing them using an adaptive weighted function to develop a new quality metric using eye traversal (QMET). Tested results reveal that the quality evaluation carried out by QMET demonstrates a strong correlation with the most widely used peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and the MOS.DICTA 2017 - 2017 International Conference on Digital Image Computing: Techniques and Application

Uniform Color Space-Based High Dynamic Range Video Compression

© 1991-2012 IEEE. Recently, there has been a significant progress in the research and development of the high dynamic range (HDR) video technology and the state-of-the-art video pipelines are able to offer a higher bit depth support to capture, store, encode, and display HDR video content. In this paper, we introduce a novel HDR video compression algorithm, which uses a perceptually uniform color opponent space, a novel perceptual transfer function to encode the dynamic range of the scene, and a novel error minimization scheme for accurate chroma reproduction. The proposed algorithm was objectively and subjectively evaluated against four state-of-the-art algorithms. The objective evaluation was conducted across a set of 39 HDR video sequences, using the latest x265 10-bit video codec along with several perceptual and structural quality assessment metrics at 11 different quality levels. Furthermore, a rating-based subjective evaluation ( $n=40$ ) was conducted with six sequences at two different output bitrates. Results suggest that the proposed algorithm exhibits the lowest coding error amongst the five algorithms evaluated. Additionally, the rate-distortion characteristics suggest that the proposed algorithm outperforms the existing state-of-the-art at bitrates ≥ 0.4 bits/pixel

Molecular Mechanisms Responsible for Functional Cortical Plasticity During Development and after Focal Ischemic Brain Injury

The cerebral cortex is organized into functional representations, or maps, defined by increased activity during specific tasks. In addition, the brain exhibits robust spontaneous activity with spatiotemporal organization that defines the brain’s functional architecture (termed functional connectivity). Task-evoked representations and functional connectivity demonstrate experience-dependent plasticity, and this plasticity may be important in neurological development and disease. An important case of this is in focal ischemic injury, which results in destruction of the involved representations and disruption of functional connectivity relationships. Behavioral recovery correlates with representation remapping and functional connectivity normalization, suggesting functional organization is critical for recovery and a potentially valuable therapeutic target. However, the cellular and molecular mechanisms that drive this systems-level plasticity are unknown, making it difficult to approach therapeutic modulation of functional brain organization. Using cortical neuroimaging in mice, this dissertation explores the role of specific genes in sensory deprivation induced functional brain map plasticity during development and after focal ischemic injury. In the three contained chapters, I demonstrate the following: 1) Arc, an excitatory neuron synaptic-plasticity gene, is required for representation remapping and behavioral recovery after focal cortical ischemia. Further, perilesional sensory deprivation can direct remapping and improve behavioral recovery. 2) Early visual experience modulates functional connectivity within and outside of the visual cortex through an Arc-dependent mechanism. 3) Electrically coupled inhibitory interneuron networks limit spontaneous activity syncrhony between distant cortical regions. This work starts to define the molecular basis for plasticity in functional brain organization and may help develop approaches for therapeutic modulation of functional brain organization

Identification of Chronic Postural Stability Impairments Associated With History of Concussion

Concussion is the most common form of traumatic brain injury (TBI). However, there is a disproportionate level of understanding between the acute and chronic impairments associated with traumatic brain injury. Specifically, problems maintaining balance during standing and walking are cardinal signs of acute concussion, but the temporal extent to which postural control deficits remain following the initial injury are not well defined or understood. The purpose of the projects composing this dissertation was to examine the long-term effects of a prior history of concussion on static (i.e. standing) and dynamic (i.e. gait) postural control. To address this, healthy adults aged 18-45 reporting a prior history of concussion(s) as well as age-matched controls with no documented concussion history were recruited to participate. Static postural control was assessed using a force plate system to track each participant’s center-of-pressure during standing. Spatiotemporal parameters as well as head stability during gait were assessed using a pressure-sensitive walkway and accelerometers placed at the head, neck, and lower trunk, respectively. The findings of these projects indicate that concussion has detrimental effects on both static and dynamic postural stability years after the initial injury and clinical determination of recovery. Specifically, individuals with a prior history of concussion demonstrated greater postural sway displacement and reduced sway regularity under dual-task conditions compared to the control group. In addition, previously concussed individuals demonstrated less variability in their gait cadence and step length, which suggests a reduction in the complexity of the neural networks contributing to postural control. Lastly, individuals with a history of concussion demonstrated greater triaxial accelerations at the head during gait, indicating a reduced ability to attenuate gait-related oscillations and stabilize the head. Collectively, these findings indicate that concussion is associated with impaired postural control that persists for years after the initial injury and well beyond the point where clinical testing protocols can identify deficits in maintaining balance. Future efforts should be directed toward incorporating more sophisticated measures and analyses of postural stability in concussion screenings to improve clinicians’ abilities to identify the scope in which concussion negatively impacts the function of the central nervous system

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 353)

This bibliography lists 238 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in August 1991. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, biotechnology, human factors engineering, and flight crew behavior and performance

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 368)

This bibliography lists 305 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System during Sep. 1992. The subject coverage concentrates on the biological, physiological, psychological, and environmental effects to which humans are subjected during and following simulated or actual flight in the Earth's atmosphere or in interplanetary space. References describing similar effects on biological organisms of lower order are also included. Such related topics as sanitary problems, pharmacology, toxicology, safety and survival, life support systems, exobiology, and personnel factors receive appropriate attention. Applied research receives the most emphasis, but references to fundamental studies and theoretical principles related to experimental development also qualify for inclusion

Aerospace medicine and biology: A cumulative index to a continuing bibliography (supplement 371)

This publication is a cumulative index to the abstracts contained in Supplements 359 through 370 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes: subject, personal author, corporate source, foreign technology, contract number, report number, and accession number

Functional Brain Organization in Space and Time

The brain is a network functionally organized at many spatial and temporal scales. To understand how the brain processes information, controls behavior and dynamically adapts to an ever-changing environment, it is critical to have a comprehensive description of the constituent elements of this network and how relationships between these elements may change over time. Decades of lesion studies, anatomical tract-tracing, and electrophysiological recording have given insight into this functional organization. Recently, however, resting state functional magnetic resonance imaging (fMRI) has emerged as a powerful tool for whole-brain non-invasive measurement of spontaneous neural activity in humans, giving ready access to macroscopic scales of functional organization previously much more difficult to obtain. This thesis aims to harness the unique combination of spatial and temporal resolution provided by functional MRI to explore the spatial and temporal properties of the functional organization of the brain. First, we establish an approach for defining cortical areas using transitions in correlated patterns of spontaneous BOLD activity (Chapter 2). We then propose and apply measures of internal and external validity to evaluate the credibility of the areal parcellation generated by this technique (Chapter 3). In chapter 4, we extend the study of functional brain organization to a highly sampled individual. We describe the idiosyncratic areal and systems-level organization of the individual relative to a standard group-average description. Further, we develop a model describing the reliability of BOLD correlation estimates across days that accounts for relevant sources of variability. Finally, in Chapter 5, we examine whether BOLD correlations meaningfully vary over the course of single resting-state scans