Differential effects of TFG-β and FGF-2 on in vitro proliferation and migration of primate retinal endothelial and Müller cells

Purpose: During retinal development, the pattern of blood vessel formation depends upon the combined effects of proliferation and migration of endothelial cells, astrocytes and Müller cells. In this study, we investigated the potential for transforming

Rockport Comprehensive Plan

This document was developed and prepared by Texas Target Communities (TxTC) at Texas A&M University in partnership with the City of Rockport, Texas Sea Grant, Texas A&M University - Corpus Christi, Texas A&M University - School of Law and Texas Tech University.Founded in 1871, the City of Rockport aims to continue growing economically and sustainably. Rockport is a resilient community dedicated to sustainable growth and attracting businesses to the area. Rockport is a charming town that offers a close-knit community feel and is a popular tourist destination for marine recreation, fairs, and exhibitions throughout the year. The Comprehensive Plan 2020-2040 is designed to guide the city of Rockport for its future growth. The guiding principles for this planning process were Rockport's vision statement and its corresponding goals, which were crafted by the task force. The goals focus on factors of growth and development including public participation, development considerations, transportation, community facilities, economic development, parks, and housing and social vulnerability

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Visual processing in the higher cortices of the mammalian visual cortex

Area 18 of the cat is the focus of this thesis as it a cortical area considered both primary visual cortex due to its direct LGN projections, but also an association visual cortex and homologue of the primate area V2. Visual cortical neurones are categorised as either simple or complex based on receptive field properties within a small, central excitatory region. But when stimuli are expanded beyond the confines of the central receptive field, a silent surround region is capable of playing a modulatory role on the centre response. Chapter 1 provides some historical background regarding the visual cortex, properties of the neuronal populations and hypothesised models associated with the construction of receptive field. Chapter 2 expands previous work from our laboratory in area 17 of the cat into area 18. In over 75% of cells in area 18 we observed to have a suppressive surround and exhibit tuning for orientation, contrast, spatial and temporal frequencies. Previously observed ‘simplification of complex cells’ (reduced phase sensitivity) in area 17 when receptive fields were co-stimulated with optimised surround stimuli was also present in area 18. Chapter 3 expands the understanding of binocular cell responses and the extent of matching for centre and surround receptive fields in area 18. Centre receptive fields demonstrated excellent matching for phase-sensitivities and orientation. Conversely, there was weak interocular matching of the optimal temporal frequencies, the diameters of summation areas of the excitatory responses and suppression index. In chapter 4, consistent with findings of area 17, we have observed silent surround which can be classified as suppressive, rebound, plateau and faciliatory. Exploring the ECRF in a subregion fashion we observed uniform suppressive ECRF in addition to heterogenous subregions capable of suppression and facilitation of the centr

Binocular neurons in parastriate cortex: interocular 'matching' of receptive field properties, eye dominance and strength of silent suppression.

Spike-responses of single binocular neurons were recorded from a distinct part of primary visual cortex, the parastriate cortex (cytoarchitectonic area 18) of anaesthetized and immobilized domestic cats. Functional identification of neurons was based on the ratios of phase-variant (F1) component to the mean firing rate (F0) of their spike-responses to optimized (orientation, direction, spatial and temporal frequencies and size) sine-wave-luminance-modulated drifting grating patches presented separately via each eye. In over 95% of neurons, the interocular differences in the phase-sensitivities (differences in F1/F0 spike-response ratios) were small (≤ 0.3) and in over 80% of neurons, the interocular differences in preferred orientations were ≤ 10°. The interocular correlations of the direction selectivity indices and optimal spatial frequencies, like those of the phase sensitivies and optimal orientations, were also strong (coefficients of correlation r ≥ 0.7005). By contrast, the interocular correlations of the optimal temporal frequencies, the diameters of summation areas of the excitatory responses and suppression indices were weak (coefficients of correlation r ≤ 0.4585). In cells with high eye dominance indices (HEDI cells), the mean magnitudes of suppressions evoked by stimulation of silent, extra-classical receptive fields via the non-dominant eyes, were significantly greater than those when the stimuli were presented via the dominant eyes. We argue that the well documented 'eye-origin specific' segregation of the lateral geniculate inputs underpinning distinct eye dominance columns in primary visual cortices of mammals with frontally positioned eyes (distinct eye dominance columns), combined with significant interocular differences in the strength of silent suppressive fields, putatively contribute to binocular stereoscopic vision

Contrast sensitivity and comparison of high vs. low eye dominance.

<p><b>A</b> Examples of contrast response functions for optimized grating patches presented via the dominant and non-dominant eyes. Note that in some cells (<b>Ai</b>) irrespective of the contrast, the response to stimuli presented via non-dominant eye is much weaker than that to stimuli presented via dominant eye. In other cells however, at low contrasts the response to stimuli presented via the dominant eye is not much stronger than that to stimuli presented via the non-dominant eye (<b>Aii</b>) or the eye dominance is reversed (<b>Aiii</b>). The C₅₀ contrasts, that is, the contrasts at which the magnitude of response to optimized stimuli confined to the sRF reached 50% of maximum response are indicted by the dashed lines. <b>B</b> Histogram showing the mean C₅₀ values of the contrast response functions of the current sample of cells when stimulated via the dominant or non-dominant eyes. <b>C</b> Frequency histograms of cells with high eye dominance indices (HEDI) and cells with low eye dominance indices (LEDI). Also shown is the equation by which eye dominance index has been determined. <b>D</b> Mean SI of HEDI and LEDI cells for stimuli presented via the dominant or non-dominant eyes. Error bars indicate SEM; ** indicate significant (P<0.01, Wilcoxon test) differences. <b>Ei</b> Scatter plot of the peak discharge rates for optimized grating patches presented via the dominant vs. optimized grating patches presented via the non-dominant eyes. <b>Eii</b> Mean peak discharges rates of HEDI and LEDI cells for stimuli presented via the dominant or non-dominant eyes. Error bars indicate SEM; # indicates marginally significant (P<0.05, Mann-Whitney test, one-tailed criterion) difference.</p

Spatial frequency cut-offs and temporal frequency tuning.

<p><b>Ai</b> Scatter plot illustrating the interocular matching of spatial frequency bandwidths; black line indicates linear regression line. <b>Aii</b> Frequency histogram of the interocular matching of SF bandwidths for simple and complex cells. <b>B</b> Histogram of the mean spatial frequency bandwidths of simple and complex cells for stimuli presented via dominant and non-dominant eyes. ** Indicates significant (P<0.01 Mann-Whitney test) difference; *** indicates significant (P<0.0005, Wilcoxon test) difference. <b>C</b> Examples of temporal frequency tuning curves for optimized (orientation, spatial frequency, size) gratings presented via dominant and non-dominant eyes. Note that in case of cell whose responses are illustrated in <b>Ci</b> there is an excellent interocular match of both optimal and high cut-off temporal frequencies. However, in case of cell whose responses are illustrated in <b>Cii</b> there are clear interocular differences in both optimal and high cut-off temporal frequencies. <b>D</b> Scatter plot showing the interocular matching of optimal temporal frequencies for the present sample of area 18 cells. <b>E</b> Histograms in <b>i</b> and <b>ii</b> illustrate respectively the optimal and high cut-off temporal frequencies for stimuli presented via the dominant and non-dominant eyes. Error bars indicate SEM.</p

Differentiating between simple and complex cells.

<p><b>A</b> Examples of peristimulus time histograms (PSTH) of responses to optimized (orientation, direction of movement, spatial and temporal frequencies, size) achromatic grating patches presented via dominant or non-dominant eyes. Histograms in <b>Ai</b> and <b>Aii</b> illustrate excellent interocular ‘matching’ of F1/F0 spike-response ratios to high-contrast grating patches optimized for each eye. Histograms in <b>Aiii</b> illustrates poor interocular matching of F1/F0 spike-response ratios. <b>B</b> Frequency histogram of F1/F0 spike-response ratios for the current sample of binocular parastriate cells to optimized grating patches presented via the dominant eyes. Note that the majority of cells that were identified as simple or complex on the basis of their F1/F0 spike-response ratios were also identified as simple or complex on the basis of Hubel and Wiesel's (1962) criteria. <b>Ci</b> Scatter plot of the magnitudes of peak discharge rates for the current sample of cells to optimized grating patches presented via the dominant vs. those to the optimized grating patches presented via the non-dominant eyes. <b>Cii</b> Histogram of the mean peak discharge rates of simple and complex cells to optimized drifting gratings presented via the dominant and the non-dominant eyes. Error bars indicate SEM. <b>Di</b> Scatter plot of F1/F0 spike-response ratios for optimized stimuli presented via the dominant eyes vs. those for optimized stimuli presented via the non-dominant eyes. <b>Dii</b> The frequency histogram illustrates the range of interocular differences in phase-sensitivity (F1/F0 spike-response ratios) elicited individually by optimized grating patches presented via the dominant and non-dominant eyes.</p

Orientation and direction selectivity.

<p><b>A</b> Examples of orientation tuning curves for optimized grating patches presented via dominant and non-dominant eyes. The simple cell in <b>Ai</b> has identical preferred orientation for stimuli presented via the dominant and the non-dominant eyes, however the orientation-tuning curve for the dominant eye is broader (greater Half-Width at Half-Height – HWHH) than that for the non-dominant eye. By contrast, in the case of the complex cell in <b>Aii</b> while the preferred orientations for stimuli presented via the dominant and non-dominant eyes differ by 20°, the HWHH of the orientation tuning curves are virtually identical. Note that in cells indicated by numbers 1, 2 and 3, the preferred orientation/axis in each eye differ by ∼180°. <b>Bi</b> Scatter plot illustrating the interocular matching of optimal orientations; linear regression of the whole sample indicates excellent orientation matching. Inset indicates our convention for defining the orientation of the stimuli; Horizontal - 90° Vertical – 0°. <b>Bii</b> Frequency histogram showing interocular differences in optimal orientation for simple and complex cells. <b>C</b> Peristimulus time histograms illustrate the responses of a ‘typical’ complex cell to optimized grating patches moving in the preferred and anti-preferred direction for stimuli presented via the dominant and non-dominant eyes. <b>D</b> Scatter plot illustrating interocular matching of direction selectivity indices (DSI). <b>E</b> Histogram of the mean DSI of simple and complex cells to optimized drifting grating patches presented via the dominant and non-dominant eyes. Error bars indicate SEM.</p

Spatial frequency tuning.

<p><b>A</b> Examples of spatial frequency tuning plots of area 18 cells for stimuli presented via the dominant and non-dominant eyes. The bandwidth represents the spatial frequency range which elicits >50% of maximal firing rate. Scatter plot in <b>Bi</b> illustrates the interocular matching of optimal spatial frequencies. Black line indicates linear regression line. <b>Bii</b> Frequency histogram of interocular differences in optimal spatial frequencies. <b>C</b> Histogram illustrating the mean optimal spatial frequencies of simple and complex cells to optimized drifting gratings presented via the dominant and non-dominant eyes. # Indicates a marginal significant (P<0.05, Mann-Whitney test, one-tailed criterion) difference. <b>D</b> Histogram showing the mean optimal spatial frequencies for stimuli presented via the dominant or non-dominant eyes for groups of simple (S) and complex (C) based on eccentricity of location of their discharge fields.</p