Vergence Fusion Sustaining Oscillations.

Introduction: Previous studies have shown that the slow, or fusion sustaining, component of disparity vergence contains oscillatory behavior as would be expected if fusion is sustained by visual feedback. This study extends the examination of this behavior to a wider range of frequencies and a larger number of subjects.

Methods: Disparity vergence responses to symmetrical 4.

Dynamics of the Disparity Vergence Fusion Sustain Component.

The stereotypical vergence response to a step stimulus consists of two dynamic components: a high velocity fusion initiating component followed by a slower component that may mediate sustained fusion. The initial component has been well-studied and is thought to be controlled by an open-loop mechanism. Less is known about the slow, or fusion sustaining component except that it must be feedback controlled to achieve the positional precision of sustained fusion.

Heme oxygenase-1-dependent central cardiorespiratory adaptations to chronic intermittent hypoxia in mice.

Chronic intermittent hypoxia (CIH) increases sympathetic tone and respiratory instability. Our previous work showed that chronic hypoxia induces the oxygen-sensing enzyme heme oxygenase-1 (HO-1) within the C1 sympathoexcitatory region and the pre-Bötzinger complex (pre-BötC). We therefore examined the effect of CIH on time course of induced expression of HO-1 within these regions and determined whether the induction of HO-1 correlated with changes in respiratory, sigh frequency, and sympathetic responses (spectral analysis of heart rate) to acute hypoxia (10% O) during 10 days of exposure to CIH in chronically instrumented awake wild-type (WT) and HO-1 null mice (HO-1).

Improved Heart Sound Detection and Signal-to-Noise Estimation Using a Low-Mass Sensor.

Goal: The purpose of this paper is to improve the detection of high-frequency sounds from the heart for better identification of turbulent blood flow in partially occluded coronary arteries. This paper also describes a method for the quantitative assessment of data quality.

Methods: A very light-weight dual accelerometer has been developed that places a small mechanical load on the chest.

Path length entropy analysis of diastolic heart sounds.

Early detection of coronary artery disease (CAD) using the acoustic approach, a noninvasive and cost-effective method, would greatly improve the outcome of CAD patients. To detect CAD, we analyze diastolic sounds for possible CAD murmurs. We observed diastolic sounds to exhibit 1/f structure and developed a new method, path length entropy (PLE) and a scaled version (SPLE), to characterize this structure to improve CAD detection.

Utility of an advanced digital electronic stethoscope in the diagnosis of coronary artery disease compared with coronary computed tomographic angiography.

The detection of coronary artery microbruits, subaudible bruits too faint to be heard through standard auscultation, may provide an alternative means to diagnose coronary artery disease (CAD). The aim of this study was to test the accuracy of a novel digital electronic stethoscope, the Cardiac Sonospectrographic Analyzer (CSA; SonoMedica model 3.0, SonoMedica, Inc.

Noise detection in heart sound recordings.

Coronary artery disease (CAD) is the leading cause of death in the United States. Although progression of CAD can be controlled using drugs and diet, it is usually detected in advanced stages when invasive treatment is required. Current methods to detect CAD are invasive and/or costly, hence not suitable as a regular screening tool to detect CAD in early stages.

Heme oxygenase-1-dependent central cardiorespiratory adaptations to chronic hypoxia in mice.

Adaptations to chronic hypoxia (CH) could reflect cellular changes within the cardiorespiratory regions of the rostral ventrolateral medulla (RVLM), the C1 region, and the pre-Bötzinger complex (pre-BötC). Previous studies have shown that the hypoxic chemosensitivity of these regions are heme oxygenase (HO) dependent and that CH induces HO-1. To determine the time course of HO-1 induction within these regions and explore its relevance to the respiratory and sympathetic responses during CH, the expression of HO-1 mRNA and protein in the RVLM and measures of respiration, sigh frequency, and sympathetic activity (spectral analysis of heart rate) were examined during 10 days of CH.

Saccadic behavior during the response to pure vergence stimuli.

If two targets are carefully aligned, the required eye movement will be symmetrical with the two eyes turning equally inward or outward: a pure vergence movement. Yet almost all responses contain saccades, a rapid tandem movement of the eyes. When saccades occur, they must either be producing an error in the desired symmetrical response or correcting an error produced by an asymmetrical vergence response.

Vergence transient component: an index to oculomotor learning modification.

The brain has a dynamic ability to change or adapt which is imperative for survival of a species. Research has shown that the dynamics of disparity vergence eye movements, the inward (convergence) or outward (divergence) turning of the eyes, are malleable and depend to some extent on the amplitude of preceding stimuli. Disparity convergence is composed of two components.

The transient component of disparity vergence maybe an indication of progressive lens acceptability.

Presbyopia, a degenerative condition, which decreases accommodation, sets in approximately at the age of forty. One approach to correct presbyopia is the use of bifocal or progressive lenses. Naturally, some people are more prone to adapt to wearing progressive lenses than others.

Acoustic detection of coronary artery disease.

Coronary artery disease (CAD) occurs when the arteries to the heart (the coronary arteries) become blocked by deposition of plaque, depriving the heart of oxygen-bearing blood. This disease is arguably the most important fatal disease in industrialized countries, causing one-third to one-half of all deaths in persons between the ages of 35 and 64 in the United States. Despite the fact that early detection of CAD allows for successful and cost-effective treatment of the disease, only 20% of CAD cases are diagnosed prior to a heart attack.

Dry dissection of disparity divergence eye movements using independent component analysis.

Dry dissection, a concept developed by Lawrence Stark, includes a variety of techniques designed to isolate internal neural control components by using cleverly designed stimulus or measurement protocols. As envisioned by Stark, the concept applies only to motor systems that have multiple stimulus inputs and/or response behaviors. A new application of independent component analysis (ICA) can be used to extend the dry dissection concept to identify motor components from a single, isolated response.

Dynamic assessment of disparity vergence ramps.

Previous work has shown that the disparity vergence eye movement system responds to inward (i.e., convergent) ramp stimuli with both smooth and step-like behavior depending on target velocity.

Optical imaging of breast tumor through temporal log-slope difference mappings.

A novel optical temporal log-slope difference mapping approach is proposed for cancerous breast tumor detection. In this method, target tissues are illuminated by near-infrared (700-1000 nm) ultrashort laser pulses from various surface source points, and backscattered time-resolved light signals are collected at the same surface points. By analyzing the log-slopes of decaying signals over all points on the source-detection grid, a log-slope distribution on the surface is obtained.

Short-term predictive changes in the dynamics of disparity vergence eye movements.

Repetitive stimulation of the disparity vergence system to large convergent step stimuli has been shown to increase the dynamics of subsequent responses to smaller step stimuli. Here we show that decreases in the dynamics of both disparity convergence and divergence eye movements can be induced using a frequently occurring small amplitude conditioning stimulus to modify responses to a larger, occasionally presented test stimulus. In one experiment, a simple conditioning stimulus consisting of repetitive 1 degrees step stimuli was used to modify the dynamic vergence response to an occasional 4 degrees step test stimulus.

Rapid phase-cycled two-dimensional optical spectroscopy in fluorescence and transmission mode.

Two dimensional magnetic and optical spectra contain information about structure and dynamics inaccessible to the linear spectroscopist. Recently, phase cycling techniques in optical spectroscopy have extended the capabilities of two-dimensional electronic spectroscopy. Here, we present a method to generate collinear pump/probe pulses at high update rates for two-dimensional electronic spectroscopy.

Divergence eye movements are dependent on initial stimulus position.

Previous studies on the speed and latency of convergence and divergence eye movements have produced varied, sometimes contradictory, results. Four subjects were studied and tracked 4 degrees disparity step changes for convergence and divergence at different initial target positions. Here we report that the dynamics of divergence movements not only differ from convergence movement, but depend on the initial vergence position.

Scheimpflug and high-resolution magnetic resonance imaging of the anterior segment: a comparative study.

High-resolution imaging with a camera system built on the Scheimpflug principle has been used to characterize the geometry of the anterior segment of the adult human eye as a function of aging and accommodative state but is critically dependent on algorithms for correction of distortion. High-resolution magnetic resonance imaging (MRI), in contrast, provides lower-resolution information about the adult eye but is undistorted. To test the accuracy of the Scheimpflug correction methods used by Cook and Koretz [J.

Magnetic resonance imaging study of the effects of age and accommodation on the human lens cross-sectional area.

Purpose: To evaluate the effect of age and accommodation on lens cross-sectional area (CSA).

Methods: High-resolution magnetic resonance images of the eye were acquired from 25 subjects ranging in age from 22 to 50 years during accommodation and with accommodation at rest. The images were analyzed to obtain the total lens CSA and the CSAs of the anterior and posterior portions of the lens.

Components of disparity vergence eye movements: application of independent component analysis.

The "dual mode" theory for the control of disparity vergence eye movements states that two control components, a preprogrammed "transient" component and a feedback-controlled "sustained" component, mediate the motor response. Although prior experimental work has isolated and studied the transient component, little is known of the sustained component's contribution to the dynamic vergence response. The timing between the two components and their relative magnitudes are of interest as they relate to the strategies used by the brain to coordinate and control the two components.

Adaptive modification of disparity vergence components: an independent component analysis study.

Purpose: Although a disparity vergence stimulus produces a smooth exponential-like response, considerable experimental evidence indicates that it is the product of at least two motor components: a pulselike transient component and a steplike sustained component. Recently, a new application of independent component analysis (ICA) has been used to decompose the vergence step response into these underlying components. Other recent experiments have shown that the vergence system is capable of rapidly modifying its dynamic characteristics (short-term adaptation) when exposed to specially designed "adapting" stimuli.