Visual Responses in Mice Lacking Critical Components of All Known Retinal Phototransduction Cascades

The mammalian visual system relies upon light detection by outer-retinal rod/cone photoreceptors and melanopsin-expressing retinal ganglion cells. Gnat1(-/-); Cnga3(-/-); Opn4(-/-) mice lack critical elements of each of these photoreceptive mechanisms via targeted disruption of genes encoding rod alpha transducin (Gnat1); the cone-specific alpha 3 cyclic nucleotide gated channel subunit (Cnga3); and melanopsin (Opn4). Although assumed blind, we show here that these mice retain sufficiently widespread retinal photoreception to drive a reproducible flash electroretinogram (ERG). The threshold sensitivity of this ERG is similar to that of cone-based responses, however it is lost under light adapted conditions. Its spectral efficiency is consistent with that of rod opsin, but not cone opsins or melanopsin, indicating that it originates with light absorption by the rod pigment. The TKO light response survives intravitreal injection of U73122 (a phospholipase C antagonist), but is inhibited by a missense mutation of cone alpha transducin (Gnat2(cpfl3)), suggesting Gnat2-dependence. Visual responses in TKO mice extend beyond the retina to encompass the lateral margins of the lateral geniculate nucleus and components of the visual cortex. Our data thus suggest that a Gnat1-independent phototransduction mechanism downstream of rod opsin can support relatively widespread responses in the mammalian visual system. This anomalous rod opsin-based vision should be considered in experiments relying upon Gnat1 knockout to silence rod phototransduction

Primal Matter

Abstract Primal Matter is a physical representation of the intuitive process, through two and three dimensional forms. The pieces convey motion and tension while telling the story of their own creation. Working instinctively has always fascinated me, in the way of allowing our subconscious mind to make decisions in the place of preconceived planning. My work is heavily influenced by Intuition and the transformation of energy. I am constantly searching for the underlying image or object through scraps of wood and pieces of charcoal, and this body of work is the visible evidence. It explores the curiosity of our unknown ideas, demonstrating a process of creation through organized chaos

Defending Noe\u27s Enactive Theory of Perception

Theories of perception can broadly be divided into two groups: orthodox and heterodox theories (Noë & Thompson, 2002). Orthodox theories of perception consider perception as a neurological process, i.e. as a phenomenon which can be explained solely in terms of intracranial facts. Heterodox views expand this scope, maintaining that an understanding of perception must include extracranial facts, or facts about the environment in which a perceiver is situated (ibid.). This thesis will attempt to defend a particular exemplar of this heterodox approach, namely the enactive theory of perception proposed by Alva Noë. The thesis has two primary goals. First, I will attempt to offer an exegesis of Noë\u27s theory, attempting to clarify the scope and strength of Noë\u27s view. Secondly, I will consider the particular objections leveled against Noë, and heterodox theories more generally, by Ken Aizawa. I conclude that Noë\u27s theory can better account for the nature of perception

The Use of Material Objects as a Secure Base

Attachment theory proposes that people form and maintain close interpersonal relationships in part because they provide a secure base for personal growth. Emerging evidence expands on this insight by showing that people sometimes seek (and find) this secure base in non-human sources (e.g., pets), particularly under conditions of threatened or absent social connection. The current research presents the first evidence that material objects can serve as a secure base, increasing felt security and the willingness to explore. Priming a valued object prevented a loss of exploration intentions following threat (Study 1). Consistent with prior research, objects effectively bolstered security and exploration particularly when uncertainty about social support was dispositionally high (Study 2) and experimentally increased (Studies 3 & 4). Study 5 showed that, in the wake of support uncertainty, an object increased exploration only if participants appraised that object as dependable--a defining characteristic of a human secure base

Attachment to Objects as a Compensatory Strategy

Attachment theory has long considered the ways in which our close relationships serve as a source of security. Psychologists have recently begun to recognize that people also derive similar feelings of security from other sources. This paper builds on this work by showing that people turn to material objects as a source of security, specifically when threatened with reminders that close others are unreliable. In two studies, we find strong empirical support for this prediction, suggesting that reminders of the unreliability of close others leads people to report greater attachment to objects (Study 1) and that this effect is mediated specifically by an increase in attachment anxiety, or concern that close others will not be sufficient to meet one's security needs (Study 2)

Near-Infrared Imaging Polarimetry of Young Stellar Objects in rho-Ophiuchi

The results of a near-infrared (J H K LP) imaging linear polarimetry survey of 20 young stellar objects (YSOs) in rho Ophiuchi are presented. The majority of the sources are unresolved, with K-band polarizations, P_K < 6 per cent. Several objects are associated with extended reflection nebulae. These objects have centrosymmetric vector patterns with polarization discs over their cores; maximum polarizations of P_K > 20 per cent are seen over their envelopes. Correlations are observed between the degree of core polarization and the evolutionary status inferred from the spectral energy distribution. K-band core polarizations >6 per cent are only observed in Class I YSOs. A 3D Monte Carlo model with oblate grains aligned with a magnetic field is used to investigate the flux distributions and polarization structures of three of the rho Oph YSOs with extended nebulae. A rho proportional to r^(-1.5) power law for the density is applied throughout the envelopes. The large-scale centrosymmetric polarization structures are due to scattering. However, the polarization structure in the bright core of the nebula appears to require dichroic extinction by aligned non-spherical dust grains. The position angle indicates a toroidal magnetic field in the inner part of the envelope. Since the measured polarizations attributed to dichroic extinction are usually <10 per cent, the grains must either be nearly spherical or very weakly aligned. The higher polarizations observed in the outer parts of the reflection nebulae require that the dust grains responsible for scattering have maximum grain sizes <=1.05 microns.Comment: 26 pages. Accepted by MNRAS. Available as online early versio

Visual responses in the dorsal lateral geniculate nucleus at early stages of retinal degeneration in rd¹ PDE6β mice

Inherited retinal degenerations encompass a wide range of diseases that result in the death of rod and cone photoreceptors, eventually leading to irreversible blindness. Low vision survives at early stages of degeneration, at which point it could rely on residual populations of rod/cone photoreceptors as well as the inner retinal photoreceptor, melanopsin. To date, the impact of partial retinal degeneration on visual responses in the primary visual thalamus (dorsal lateral geniculate nucleus, dLGN) remains unknown, as does their relative reliance on surviving rod and cone photoreceptors vs. melanopsin. To answer these questions, we recorded visually evoked responses in the dLGN of anesthetized rd1 mice using in vivo electrophysiology at an age (3–5 wk) at which cones are partially degenerate and rods are absent. We found that excitatory (ON) responses to light had lower amplitude and longer latency in rd1 mice compared with age-matched visually intact controls; however, contrast sensitivity and spatial receptive field size were largely unaffected at this early stage of degeneration. Responses were retained when those wavelengths to which melanopsin is most sensitive were depleted, indicating that they were driven primarily by surviving cones. Inhibitory responses appeared absent in the rd1 thalamus, as did light-evoked gamma oscillations in firing. This description of fundamental features of the dLGN visual response at this intermediate stage of retinal degeneration provides a context for emerging attempts to restore vision by introducing ectopic photoreception to the degenerate retina

Development of a right-of-way cost estimation and cost estimate management process framework for highway projects

Escalation of right-of-way (ROW) costs have been shown to be a prime contributor to project cost escalation in the highway industry. Two problems contribute to ROW cost escalation: 1) the ROW cost estimation and cost estimate management process generally lacks structure and definition as compared to other areas of cost estimation; and 2) there is a lack of integration and communication between those responsible for ROW cost estimating and those responsible for general project cost estimating. The research for this thesis was preceded by a literature review to establish the basis for the study. Data collection was completed through interviews of seven state highway agencies (SHAs) and two local public agencies (LPAs). The findings of the research are presented in a set of ROW flowcharts which document the steps, inputs, and outputs of the ROW cost estimation and cost estimate management process. Three ROW cost estimates and a cost management process take place throughout project development. An effort was made from the onset of the research to relate the ROW cost estimating and cost estimate management process to the first four project development phases (planning, programming. preliminary design, and final design). There are five flowcharts produced as a result of this research: 1) an agency-level flowchart showing all cost estimates and the interaction of ROW with the project development process; 2) a conceptual ROW cost estimating flowchart which depicts the required steps during planning; 3) a baseline ROW cost estimating flowchart which depicts the required steps during programming; 4) an update ROW cost estimating flowchart which depicts the required steps during preliminary design to include a cost estimate management loop; and 5) a ROW cost management flowchart which depicts the required steps during final design. Although selected SHA contacts provided input following the development of the flowcharts, the flowcharts were only validated to a limited extent due to time and budget constraints. These flowcharts attempt to address the two contributing problems to ROW cost escalation by providing structure to the ROW cost estimation process and by developing the ROW process flowcharts linked to the project development process. Based on the input provided by SHA contacts, the flowcharts appear to have the potential to provide guidance to SHAs in improving the accuracy of ROW cost estimates through addressing these two problems