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PubMed1992

Is visual lateralization in pigeons sex-dependent?

Adult homing pigeons (Columba livia) of both sexes were trained binocularly on a successive pattern discrimination task. After reaching criterion they performed the task on alternate sessions under monocular left or right viewing conditions. Regardless of their gender, all animals reached higher pecking scores when sight was restricted to the right eye. Due probably to a ceiling effect, the discrimination-accuracy scores did not differ between left and right condition. Thus, at least with respect to the number of responses emitted, a sex dependency of visual lateralization could not be demonstrated. The results are discussed in the light of studies which demonstrate that male and female pigeons have similar anatomical asymmetries of their optic tecta.

Animals↗
PubMed2003

[Steroid induced glaucoma].

Steroid treatment has gained notoriety due to its tendency to induce multiple side effects, including a variety of ocular side effects. Administration of local, regional, inhalation or systemic steroids may induce the development of ocular hypertension, which might even result in subsequent open angle glaucoma. About one in every three people is considered a potential "steroid responder". A significant elevation of intraocular pressure might result in these patients in response to steroid treatment. Included in this group are patients with first degree relatives suffering from open angle glaucoma. Morphologic changes in the trabecular meshwork (which serves as the site of aqueous humor drainage from the eye) are suggested as the proposed mechanism through which steroid treatment results in glaucoma. Steroids are said to induce the expression of a gene that is located on chromosome 1 and is known as TIGR or GLCIA. its product is a protein called myocilin. Ocular hypertension secondary to steroid treatment is usually reversible, when treatment is limited to a period of less than 12 months. The fear of ocular hypertension, which is usually unnoticed by the patient, obligates regular ophthalmologic follow-up examinations, including tonometry, visual fields and optic disc examinations.

Chromosome Mapping↗
PubMed1983

Postnatal development of the geniculocortical projection in the cat: electrophysiological and morphological studies.

Using laminar field potential analysis, we examined responses elicited by both photic and optic nerve stimulations in 30 kittens of 0--65 days of age and in three adult cats. In adult cats, the response in the visual cortex on optic nerve stimulations is a wave complex which consists mainly of surface positive depth negative (sP-dN) potentials. By contrast, the response in neonates consists of two surface negative - depth positive (sN-dP) waves. In 2 weeks, preceding the sN-dP waves, an sP-dN wave appears. As age increases, the sP-dN wave becomes of higher voltage and the sN-dP waves become of lower voltage. Thus, the configuration of the response resembles that of adult cats in 3--4 weeks. Both photic and optic nerve stimulations elicit responses of the same configuration in the same area. The extent of the response area is exactly the same at any age as in adult cats. Using the orthograde HRP method, we examined terminals of the geniculocortical afferent in 23 kittens of 0--43 days of age. The density of labeled terminals in layer I is much higher in kittens before 1 week of age (n = 8) than in kittens after 1 month of age (n = 5), whereas the density of labeled terminals in layer IV is higher in the older kittens than in the younger kittens. These electrophysiological and morphological changes are correlated in reference to the maturation of the neuronal circuit in the visual cortex.

Aging↗
PubMed2002

Identification and tissue mapping of APGWamide-related peptides in Sepia officinalis using LC-ESI-MS/MS.

This paper demonstrates for the first time the occurrence of tetrapeptides related to APGWamide in the mollusk cephalopod Sepia officinalis. LC-ESI-MS/MS analysis allowed the identification of the APGWamide-related peptides predicted by the two genes cloned previously in Lymnaea stagnalis and in Mytilus edulis, as well as the dipeptide GWamide released from the processing of the tetrapeptides by a dipeptidyl aminopeptidase (DPAP). TPGWamide and GWamide appeared to be exclusively located in the CNS, and the APGWamide in both the CNS and the nerve endings. The RPGWamide and the KPGWamide were not detected by LC-ESI-MS/MS suggesting they could be totally processed into GWamide. The in vitro processing of the tetrapeptides into GWamide by optic lobe extract revealed a differential processing for each, with APGWamide (44.7%)>RPGWamide(24.3%)>KPGWamide(19.3%)>TPGWamide (11.7%). The tissue mapping results, together with the processing efficiency data suggest that the GWamide is mainly produced from the M. edulis gene products RPGWamide and KPGWamide.

Animals↗
PubMed1987

Activity-dependent sharpening of the regenerating retinotectal projection in goldfish: relationship to the expression of growth-associated proteins.

During regeneration of the optic nerve in goldfish, manipulations that disrupt the transmission of patterned visual information, if applied within the so-called 'sensitive period', lead to the formation of a diffuse retinotopic map (Schmidt, Cell. Mol. Neurobiol., 5 (1985) 65). The present study examined: (a) whether the sensitive period (14-50 days postcrush) coincides with the period in which specific 'growth-associated proteins' are present in the regenerating optic nerve terminals; and (b) whether manipulations that alter physiological activity during the sensitive period influence the expression of these proteins. Following bilateral optic nerve crush, goldfish regenerated their optic nerves either under normal illumination conditions (control), in total darkness, or with physiological activity suppressed in the nerve by intraocular injections of tetrodotoxin (TTX). At various times postcrush, proteins conveyed from the retina to the developing nerve endings were visualized by labeling the eye with [35S]methionine and then analyzing, by 2-dimensional gel electrophoresis and fluorography, radiolabeled proteins present in the optic tectum 15 h later. Rapidly-transported proteins that underwent large, specific increases during regeneration included the previously described 48 kDa growth-associated protein (GAP-48); labeling of GAP-48 was maximal during axonal outgrowth and then declined, but still remained well above background levels throughout the 'sensitive period'. Another group of rapidly-transported proteins, mol. wt. = 110-140 kDa (HMW), followed a similar time course, while levels of a 28 kDa protein peaked at 2 weeks and then declined rapidly. Thus, activity-dependent 'sharpening' processes occur during a period in which the levels of GAP-48 and HMW remain elevated in the nerve terminals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Insect myotropic peptides: differential distribution of locustatachykinin- and leucokinin-like immunoreactive neurons in the locust brain.

Locustatachykinin I is one of four closely related myotropic neuropeptides isolated from brain and corpora-cardiaca complexes of the locust Locusta migratoria. Antiserum was raised against locustatachykinin I for use in immunocytochemistry. It was found that the antiserum recognizes also locustatachykinin II and hence probably also the other two locustatachykinins due to their similarities in primary structure. Locustatachykinin-like immunoreactive (LomTK-LI) neurons were mapped in the brain of the locust, L. migratoria. A total of approximately 800 LomTK-LI neurons were found with cell bodies distributed in the proto-, deuto- and tritocerebrum, in the optic lobes and in the frontal ganglion. Processes of these neurons innervate most of the synaptic neuropils of the brain and optic lobes, as well as the frontal ganglion and hypocerebral ganglion. The widespread distribution of LomTK-LI neurons in the locust brain indicates an important role of the locustatachykinins in signal transfer or regulation thereof. As a comparison neurons were mapped with an antiserum against the cockroach myotropic peptide leucokinin I. This antiserum, which probably recognizes the native peptide locustakinin, labels a population of about 140 neurons distinct from the LomTK-LI neurons (no colocalized immunoreactivity). These neurons have cell bodies that are distributed in the proto- and tritocerebrum and in the optic lobe. The processes of the leucokinin-like immunoreactive (LK-LI) neurons do not invade as large areas in neuropil as the LomTK-LI neurons do and some neuropils, e.g. the mushroom bodies, totally lack innervation by LK-LI fibers. In some regions, however, the processes of the LomTK-LI and LK-LI neurons are superimposed: most notably in the central body and optic lobes. A functional relation between the two types of neuropeptide in the locust brain can, however, not be inferred from the present findings.

Amino Acid Sequence↗
PubMed2000

Spatially confined and temporally resolved refractive index and scattering evaluation in human skin performed with optical coherence tomography.

In the present applications of optical coherence tomography (OCT), parameters besides pure morphology are evaluated in skin tissue under in vivo conditions. Spatially mapped refractive indices and scattering coefficients may support tissue characterization for research and diagnostic purposes in cosmetics/pharmacy and medicine, respectively. The sample arm of our OCT setup has been arranged to permit refractive index evaluation with little mechanical adjustment of a lens within the objective. A simple algorithm has been derived. Known from atmospheric work, the Klett algorithm [J. D. Klett, "Stable analytical inversion solution for processing LIDAR returns," Appl. Opt. 20(2), 211-220 (1981)] has been applied to the same data set for retrieval of scattering coefficients. Both parameters have been measured in layered structures in skin like stratum corneum, epidermis and dermis. Significant water content in a localized sweat gland duct has been observed by refractive index evaluation. Time studies over 1.5 h permitted a first understanding about physiological changes in skin which are not obtainable by intrusive methods.

Algorithms↗
PubMed1993

Functional grouping of the cortico-pretectal projection.

The ascendency of the cerebral cortex in mammals naturally raises questions about the role of the archetypal subcortical centers we share in common with other phyla. Here we report a situation in which an ancient oculomotor control center, the nucleus of the optic tract, is not so much dominated by the cerebral cortex as served by it. We suggest that the organization of cortical output to subcortical centers may be helpful in understanding the function of the cerebral cortex.

Animals↗
PubMed2003

Mapping multiple features in the population response of visual cortex.

Stimulus features such as edge orientation, motion direction and spatial frequency are thought to be encoded in the primary visual cortex by overlapping feature maps arranged so that the location of neurons activated by a particular combination of stimulus features can be predicted from the intersections of these maps. This view is based on the use of grating stimuli, which limit the range of stimulus combinations that can be examined. We used optical imaging of intrinsic signals in ferrets to assess patterns of population activity evoked by the motion of a texture (a field of iso-oriented bars). Here we show that the same neural population can be activated by multiple combinations of orientation, length, motion axis and speed. Rather than reflecting the intersection of multiple maps, our results indicate that population activity in primary visual cortex is better described as a single map of spatiotemporal energy.

Animals↗
PubMed1981

Topographic and morphometric effects of bilateral embryonic eye removal on the optic tectum and nucleus isthmus of the leopard frog.

Rana pipiens were raised through metamorphosis after extirpation of both eye primordia at Shumway embryonic stage 17 (Shumway '40). The visual connections between the isthmic nuclei and the optic tectum were examined in these animals using horseradish peroxidase (HRP) histochemistry. Isthmo-tectal projections are normally aligned with the primary retinotectal map. We asked whether these connections would develop normal topographic organization in the absence of normal retinal input. HRP was formed into a solid pellet (congruent to 200-500 micrometer diameter) and inserted into one tectal lobe on the tip of a fine metal probe. The procedure produced relatively restricted retrograde label in somas and dendrites in both isthmi nuclei. In the nucleus isthmus ipsilateral to the tectal lobe receiving the HRP pellet, processes of tecto-isthmi neurons were labeled by anterograde transport. The topography of the isthmo-tectal and tecto-isthmic projections were identical in the developmentally enucleated animals and in normal frogs, even though eye removal severely reduced the volume of the optic tecta and the isthmi nuclei. Thus our analyses indicate that retinal contacts do not play an active role in the development of the positional or polarity cues that are involved in "mapping" projections between central visual nuclei. These results are discussed in the context of peripheral specification of central connections and in terms of models that have recently been proposed to explain the development of the retinotectal system.

Animals↗
PubMed2001

[Renal hemodynamic effect of angiotensin II type 2 receptor].

In the present study, the role of the angiotensin II type 2 receptor in the regulation of medullary blood flow in conscious Spontaneous Hypertensive Rats(SHR) was investigated. We tested the hypothesis that AT2 receptor activation may exert the opposite effects of AT1 receptors in terms of renal hemodynamics. Mean arterial pressure(MAP), daily sodium balance, cortical blood flow(CBF), and medullary blood flow(MBF) were measured over a 10-day protocol in several groups of rats in which optical fibers for laser-Doppler flowmetry had been implanted and which received the following drug combinations: the AT1 receptor antagonist CV11976(CV) alone and CV plus AT2 receptor antagonist PD123319 (PD). In the CV alone group, the renal interstitial administration of CV decreased MAP, caused sodium diuresis, and increased MBF significantly. In the CV plus PD group, the renal interstitial administration of PD prevented sustained hypotension, sodium diuresis, and increased medullary blood flow during CV administration. These data indicated that AT2 receptor activation leads to vasodilation in the renal medulla and an antihypertensive effect in SHR. AT2 receptors play an important role in the renal medullary blood flow.

Animals↗
PubMed1984

Geometrical structures determined by the functional order in nervous nets.

The functional order of a collection of neural elements may be defined as the order induced through the total of covariances of signals carried by the members of the collection. Thus functional order differs from geometrical order (e.g. somatotopy) in that geometrical order is only available to external observers, whereas functional order is available to the system itself. It has been shown before that the covariances can be used to construct a partially ordered set that explicitely represents the functional order. It is demonstrated that certain constraints, if satisfied, make this set isomorphic with certain geometrical entities such as triangulations. For instance there may exist a set of hyperspheres in a n-dimensional space with overlap relations that are described with the same partially ordered set as that which describes the simultaneous/successive order of signals in a nerve. Thus it is logically possible that the optic nerve carries (functionally) two-dimensional signals, quite apart from anatomical considerations (e.g. the geometrically two-dimensional structure of the retina which exists only to external observers). The dimension of the modality defined by a collection of nervous elements can in principle be obtained from a cross-correlation analysis of multi-unit recordings without any resort to geometrical data such as somatotopic mappings.

Animals↗
PubMed2004

Wave-front reconstruction from shear phase maps by use of the discrete Fourier transform.

Fast wave-front reconstruction methods are becoming increasingly important, for example, in large astronomical adaptive optics systems and high spatial resolution shear interferometry, where pseudoinverse matrix methods scale poorly with problem size. Wave-front reconstruction from difference measurements can be achieved by use of fast implementations of the discrete Fourier transform (DFT), obtaining performance comparable with that of the pseudoinverse in terms of the noise propagation coefficient. Existing methods that are based on the use of the DFT give exact results (in the absence of noise) only for the particular case in which the shear is a divisor of the number of samples to be reconstructed. We present two alternate solutions for the more general case when the shear is any integer. In the first solution the dimensions of the problem are enlarged, and in the second the problem is subdivided into a set of smaller problems with shear amplitude equal to one. We also show that the retrieved solutions have minimum norm and calculate the noise propagation coefficient for both methods. The proposed algorithms are implemented and timed against pseudoinverse multiplication. The results show a speed increase by a factor of 50 over the pseudoinverse multiplication for a grid with N = 3 x 10(3) samples.

Journal Article↗
PubMed1995

The further construction of the two-dimensional database of common human proteins.

The master two-dimensional gel database (D. Burggraf et al., Electrophoresis 1992, 13, 729-732) [1] of common human proteins has been expanded to include detailed protein characteristics. Human cellular proteins from 5 cell lines and different cell organelles representing various tissues (muscle, nervous, connective, epithelial blood) and germ layers (ectoderm, endoderm and mesoderm), were separated by two-dimensional gel electrophoresis (2-DE). According to a recently developed algorithm, master gels of these different cells were established by computer-aided image processing. An expanded map with protein-chemical information of the polypeptides common to all human cells is shown. The synthetic, common human protein-map represents 856 spots resolved with an accuracy of 4 cm/pI unit. The protein spots were characterized either by their isoelectric point, molecular mass, integrated intensity, background-corrected optical density, spot area, or cellular distribution. About 80 proteins were further characterized and identified by protein name, amino acid composition analysis, N-terminal sequencing, enzymatic digest and subsequent peptide sequencing. Additionally the proteins of the common human protein map were identified by Western blotting. Specific information regarding glycosylation and quantitation of expression levels after chemical, biological and mechanical stimulation is included in the database.

Amino Acid Sequence↗
PubMed1979

Connections and visual-field mapping in cat's tectoparabigeminal circuit.

1. The aim of these experiments was to analyze the organization of the reciprocal connections between the cat's superior colliculus and parabigeminal nucleus. Both physiological and anatomical techniques were employed. 2. A population of cells in the superficial gray and upper optic layers of the colliculus was labeled retrogradely by horseradish peroxidase injections into the parabigeminal nucleus. No other sources of input to the nucleus were found in the brain stem or diencephalon. 3. A map of the visual field within the parabigeminal nucleus was reconstructed by plotting visual receptive fields at 350 parabigeminal sites with microelectrodes. The map resembled that found in the colliculus, although it was considerably less orderly. The entire contralateral visual field was represented and, in addition, roughly the central 40 degrees of the ipsilateral hemifield was included; futhermore, the expansion of the central visual field was similar to that of the tectal map. 4. The return parabigeminal projections to the caudal parts of the two colliculi, representing the contralateral hemifields, were in register with the tectal visual-field maps. In contrast, the parabigeminal pathways to the anterior segments of the two colliculi, representing part of the ipsilateral visual fields, were not clearly topographic. The projection to this part of the contralateral colliculus showed little order, while that to the ipsilateral colliculus was extremely sparse. 5. A single site in the colliculus can be the target of axons from nonhomologous locations in the two parabigeminal nuclei; so that both parabigeminal inputs are in register with the tectal map.

Animals↗
PubMed1995

Morphometry of the optic nerve and retinal vessels in children by computer-assisted image analysis of fundus photographs.

BACKGROUND: The retinal fundus in childhood has a different morphology than in adulthood. Existing methods are not suitable for evaluation of fundus photographs from children. Therefore, a new method for quantitative analysis of fundus morphology utilizing a personal computer-assisted digital mapping system was developed. METHODS: A CCD flatbed scanner is used to digitize fundus photographs, producing computer images which are analyzed on an IBM/AT computer. Area measurements of the optic disc, excavation and peripapillary crescent are made, as well as determinations of the length, branching, tortuosity and distribution of the retinal vessels on the fundus surface. RESULTS: Determination of the inter- and intra-observer variability of the computer-assisted image analysis technique demonstrated good reproducibility. The method is demonstrated using fundus photographs of six normal children and six children with the fetal alcohol syndrome. Typical variations in appearance of optic disc and retinal vessels are seen. CONCLUSION: The system is unique in measuring both the optic nerve head and the retinal vessels and is therefore especially useful for detailed studies of normal and abnormal development of these structures in children.

Adolescent↗