Inactivation of the superior cerebellar peduncle blocks expression but not acquisition of the rabbit's classically conditioned eye-blink response.

The localization of sites of memory formation within the mammalian brain has proven to be a formidable task even for simple forms of learning and memory. Recent studies have demonstrated that reversibly inactivating a localized region of cerebellum, including the dorsal anterior interpositus nucleus, completely prevents acquisition of the conditioned eye-blink response with no effect upon subsequent learning without inactivation. This result indicates that the memory trace for this type of learning is located either (i) within this inactivated region of cerebellum or (ii) within some structure(s) efferent from the cerebellum to which output from the interpositus nucleus ultimately projects. To distinguish between these possibilities, two groups of rabbits were conditioned (by using two conditioning stimuli) while the output fibers of the interpositus (the superior cerebellar peduncle) were reversibly blocked with microinjections of the sodium channel blocker tetrodotoxin. Rabbits performed no conditioned responses during this inactivation training. However, training after inactivation revealed that the rabbits (trained with either conditioned stimulus) had fully learned the response during the previous inactivation training. Cerebellar output, therefore, does not appear to be essential for acquisition of the learned response. This result, coupled with the fact that inactivation of the appropriate region of cerebellum completely prevents learning, provides compelling evidence supporting the hypothesis that the essential memory trace for the classically conditioned eye-blink response is localized within the cerebellum.

Immunolocalization of the mercurial-insensitive water channel and glycerol intrinsic protein in epithelial cell plasma membranes.

Two water channel homologs were cloned recently from rat kidney, mercurial-insensitive water channel (MIWC) and glycerol intrinsic protein (GLIP). Polyclonal antibodies were raised against synthetic C-terminal peptides and purified by affinity chromatography. MIWC and GLIP antibodies recognized proteins in rat kidney with an apparent molecular mass of 30 and 27 kDa, respectively, and did not cross-react. By immunofluorescence, MIWC and GLIP were expressed together on the basolateral plasma membrane of collecting duct principal cells in kidney. By immunohistochemistry, MIWC and GLIP were expressed on tracheal epithelial cells with greater expression of GLIP on the basal plasma membrane and MIWC on the lateral membrane; only MIWC was expressed in bronchial epithelia. In eye, GLIP was expressed in conjunctival epithelium, whereas MIWC was found in iris, ciliary body, and neural cell layers in retina. MIWC and GLIP colocalized on the basolateral membrane of villus epithelial cells in colon and brain ependymal cells. Expression of MIWC and GLIP was not detected in small intestine, liver, spleen, endothelia, and cells that express water channels CHIP28 or WCH-CD. These studies suggest water/solute transporting roles for MIWC and GLIP in the urinary concentrating mechanism, cerebrospinal fluid absorption, ocular fluid balance, fecal dehydration, and airway humidification. The unexpected membrane colocalization of MIWC and GLIP in several tissues suggests an interaction at the molecular and/or functional levels.

Evidence for a hypothalamothalamocortical circuit mediating pheromonal influences on eye and head movements.

A method for simultaneous iontophoretic injections of the anterograde tracer Phaseolus vulgaris leukoagglutinin and the retrograde tracer fluorogold was used to characterize in the rat a hypothalamothalamocortical pathway ending in a region thought to regulate attentional mechanisms by way of eye and head movements. The relevant medial hypothalamic nuclei receive pheromonal information from the amygdala and project to specific parts of the thalamic nucleus reuniens and anteromedial nucleus, which then project to a specific lateral part of the retrosplenial area (or medial visual cortex). This cortical area receives a convergent input from the lateral posterior thalamic nucleus and projects to the superior colliculus. Bidirectional connections with the hippocampal formation suggest that activity in this circuit is modified by previous experience. Striking parallels with basal ganglia circuitry are noted.

Prenatal monocular enucleation induces a selective loss of low-spatial-frequency cortical responses to the remaining eye.

During early development, interactions between the two eyes are critical in the formation of eye-specific domains within the lateral geniculate nucleus and the visual cortex. When monocular enucleation is done early in prenatal life, it induces remarkable anatomical and functional reorganizations of the visual pathways. Behavioral data have shown a loss in sensitivity to low-spatial-frequency gratings in cats. To correlate the behavioral observations with a possible change in the analysis of contrast at the level of primary visual areas we recorded visual evoked potentials at the 17/18 border in two cats enucleated prenatally (gestational age at enucleation, 39-42 days), three neonatal, two control animals, and one animal with a surgical removal of Y-ganglion fibers. Our results show a strong attenuation in the amplitude of response at all contrast values for gratings of low spatial frequency in prenatally enucleated cats, whereas neonatally enucleated and control animals present responses of comparable amplitude. We conclude that the behavioral results reflect the reduced sensitivity for low frequencies of visual cortical neurons. In addition, we define a critical period for the development of the contrast-sensitivity function that seems to be limited to the prenatal gestation period. We suggest that the prenatal interruption of binocular interactions leads to a functional elimination of the Y-ganglion system.

Immunocytochemical study on the triple origin of the sphincter iris in the chick embryo

The ontogenic development of the sphincter iris has been studied by immunocytochemistry and standard staining on chick embryos from stage 25 HH to the time of hatching. We have used the monoclonal antibody 13F4, a highly specific marker of muscular cells. We have observed three different regions in the iris. Tn the pupillary region, immunoreactive cells are in continuous contact with the inner epithelium of the pupillary margin. In the intermediate region, the outer epithelium forms buds of pigmented cells that emigrate toward the stroma. In this epithelium cells that are totally or partially unpigmented exist, and they are 13F4 positive. In the sphincter we have observed 13F4 positive cells with melanin granules. In the ciliary region, the immunoreactivity appears in dispersed mesenchymal cells. The present findings are consistent with a triple origin of the sphincter iris in the chick embryo. This muscle is derived from the inner epithelium of the pupillary margin, the intermediate region of the outer epithelium, and from the mesenchymal cells. The cells of the inner epithelium of the pupillary margin are differentiated into smooth muscle cells, and the remaining cells form striated muscle cells.

Privy Private Eye: A Guidebook for Travelers Who Have to Go

This creative Capstone project, Privy Private Eye: A Guidebook for Travelers Who Have to Go, contains a nonfiction compendium of brief reviews of public restrooms in the Dallas, Texas area. To inform readers about facilities that are safe (and a few that should be avoided), Privy Private Eye contains reviews and ratings of restrooms in gas stations, restaurants, and retail centers. These appraisals will be featured in a full-length manuscript that may be published in the near future as a travel guide. Also contained herein, before the creative portion of the project itself, is a reflective paper describing the project, its creation, and its position within the context of published travel guides.

Kinematics of eyelid movement and eye retraction in the blinking

Resumen del póster expuesto en el 6th EOS Topical Meeting on Visual and Physiological Optics (EMVPO 2012), Dublín, 20-22 Agosto 2012.

Kinematics of eyelid movement and eye retraction in the blinking [Poster]

Póster presentado en el 6th EOS Meeting on Visual and Physiological Optics (EMVPO 2012), Dublín, 20-22 Agosto 2012.

Analysis of fixational eye micromovements through pupil tracking

Póster presentado en OPTYKA Optical Fair 2012, Poznan, Polonia, 9-10 noviembre 2012.

Intrasubject repeatability in keratoconus-eye measurements obtained with a new Scheimpflug photography–based system

Purpose: To evaluate in keratoconus eyes the intrasubject repeatability of anterior and posterior corneal curvature and of other anterior segment anatomic measurements obtained with a new topography system combining Scheimpflug-photography and Placido-disk technology. Setting: Vissum Corporation, Alicante, Spain. Design: Evaluation of technology. Methods: All keratoconus eyes had a comprehensive ophthalmologic examination including analysis with the Sirius system. Three consecutive measurements were obtained to assess the intrasubject repeatability of the following parameters: anterior and posterior corneal curvature and shape factor, white-to-white (WTW) corneal diameter, central and minimum corneal thickness, and anterior chamber depth (ACD). The within-subject standard deviation (Sw) and intraclass correlation coefficient (ICC) were calculated. Results: This study comprised 61 eyes of 61 patients ranging in age from 14 to 64 years. For anterior and posterior corneal curvatures and power vector components, the Sw was 0.29 mm or less in all cases. The ICC was above 0.990 in all cases except the flattest curvature of the posterior corneal surface at 3.0 mm, which was 0.840 (moderate agreement), and the posterior power vector J0, which was 0.665 (poor agreement), 0.752, and 0.758 (moderate agreement) for 3.0 mm, 5.0 mm, and 7.0 mm, respectively. In shape factor measurements, the Sw was 0.12 or less in all cases and the ICC ranged between 0.989 and 0.999. Pachymetry, ACD, and WTW had ICC values very close to 1. Conclusion: The new topography system provided repeatable measurements of corneal shape and other anatomic parameters in eyes with keratoconus.

Correlation of the Corneal Toricity Between Anterior and Posterior Corneal Surfaces in the Normal Human Eye

Purpose: To evaluate the correlation of the magnitude of corneal toricity and power vector components of both corneal surfaces measured with a Scheimpflug photography-based system. Methods: A total of 117 healthy normal eyes of 117 subjects selected randomly with ages ranging from 7 to 80 years were included. All eyes received an anterior segment and corneal analysis with the Sirius system (CSO) evaluating the anterior and posterior mean toricity for 3 and 7 mm (aAST and pAST). The vector components J0 and J45 as well as the overall strength blur (B) were calculated for each keratometric measurement using the procedure defined by Thibos and Horner. Results: The coefficient of correlation between aAST and pAST was 0.52 and 0.62 and the mean anteroposterior ratio for toricity was 0.46 ± 0.39 and 0.57 ± 0.75 for 3 and 7 mm, respectively. These ratios correlated significantly with aAST, anterior corneal J0, and manifest refraction J0 (r ≥ 0.39, P < 0.01). The coefficient of correlation was 0.69 and 0.81 between anterior and posterior J0 for 3 and 7 mm, respectively. For J45, the coefficients were 0.62 and 0.71, respectively. The linear regression analysis revealed that the pAST and power vectors could be predicted from the anterior corneal data (R2 ≥ 0.40, P < 0.01). Conclusions: The toricity and astigmatic power vector components of the posterior corneal surface in the human healthy eye are related to those of the anterior and therefore can be predicted consistently from the anterior toricity and astigmatic power vectors.