Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Optical mapping”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1992

Optical imaging of architecture and function in the living brain sheds new light on cortical mechanisms underlying visual perception.

Long standing questions related to brain mechanisms underlying perception can finally be resolved by direct visualization of the architecture and function of mammalian cortex. This advance has been accomplished with the aid of two optical imaging techniques with which one can literally see how the brain functions. The upbringing of this technology required a multi-disciplinary approach integrating brain research with organic chemistry, spectroscopy, biophysics, computer sciences, optics and image processing. Beyond the technological ramifications, recent research shed new light on cortical mechanisms underlying sensory perception. Clinical applications of this technology for precise mapping of the cortical surface of patients during neurosurgery have begun. Below is a brief summary of our own research and a description of the technical specifications of the two optical imaging techniques. Like every technique, optical imaging also suffers from severe limitations. Here we mostly emphasize some of its advantages relative to all alternative imaging techniques currently in use. The limitations are critically discussed in our recent reviews. For a series of other reviews, see Cohen (1989).

Brain↗
PubMed1998

Mapping structural to functional damage in glaucoma with standard automated perimetry and confocal scanning laser ophthalmoscopy.

PURPOSE: To develop a quantitative method for analysis of the topographic relationship between structural and functional damage in patients with glaucoma. METHODS: We studied 26 patients with primary open-angle glaucoma, focal optic disk damage, and focal visual field loss. The visual field was evaluated with automated perimetry, and the optic disk topography was assessed with a confocal scanning laser ophthalmoscope. Topographic measurements were calculated in 10-degree sectors and compared with a normative database (n=52). The topographic relationship of structural damage and functional loss was analyzed. RESULTS: Rim area ratio was defined as the ratio of rim area in each 10-degree sector divided by the total rim area. This ratio resulted in the identification of one (46%) or more (54%) clusters of optic disk sectors as outside normal limits in all 26 patients (12 and 14 patients, respectively). Twenty-two patients (84%) with superior hemifield sensitivity loss tended to have inferior rim defects, and vice versa. Nasal visual field defects close to the horizontal midline were matched with damaged rim areas close to the vertical midline. CONCLUSIONS: This mapping method allows an objective and quantitative evaluation of the optic disk and visual field in patients with glaucoma and focal damage. Although the topographic relationship between structure and function is characterized by considerable interindividual variability, the identification of certain patterns may be useful to aid in the evaluation of glaucomatous damage.

Adult↗
PubMed1975

Readjustment of retinotectal projection following reimplantation of a rotated or inverted tectal tissue in adult goldfish.

1. The pattern of visual projection from the retina on to the optic tectum following reimplantation of a piece of the tectal tissue was studied with neurophysiological mapping methods in adult goldfish. 2. When a rectangular piece of the tectum was dissected, lifted free, and then reimplanted to the same tectum after rotation by 180 degrees around the dorsoventral axis, the re-established visual projection later showed a complete reversal of retinotopic order within the reimplanted area with reference to the normal projection on to the intact surrounding area of the same tectum. The localized reversal was observed as early as 65 days, and also as late as 721 days after the 180 degree rotated reimplantation. 3. If a square piece of the tectal tissue was reimplanted after rotation by 90 degrees anticlockwise around the dorsoventral axis, the restored visual projection later showed a corresponding localized 90 degrees rotation within the reimplanted ares. 4. When the entire laminar structure of a dissected tectal tissue was inverted, and the reimplanted upside-down along the same rostrocaudal axis of the tectum, the restored visual projection on to the inverted tectal reimplant was found to be organized in a reverse retinotopic order along only the mediolateral axis within the reimplanted area. The restored visual projection retained a correct retinotopic order along the rostrocaudal axis. The same trends were also observed after regeneration of the optic fibres following section of the contralateral optic nerve. 5. If the inverted tectal tissue was reimplanted along the same mediolateral axis of the tectum, the re-established visual projection showed a localized reversal of retinotopic order along only the rostrocaudal axis within the reimplanted area. Sectioning the contralateral optic nerve made no difference to the result. 6. These results suggest that a piece of adult tectal tissue retains its original topographic polarity regardless of the orientation of reimplantation after either a rotation or an inversion. Furthermore the retention is not a short-lived transitory phenomenon. It persisted as long as the reimplanted tissue survived. 7. Histological examination of the operated tecta revealed that the reimplanted tectal tissues underwent a severe derangement in their laminar structures. It was impossible to identify the main target zone of retinotectal projection (the stratum fibrosum et griseum superficiale) or the central cellular layer (the stratum griseum centrale) in the reimplants. The prominent feature of the deranged tectal tissue was irregular vortices of tangled fibre bundles. Sparse tectal neurones of bipolar and granular types were irregularly scattered in the deranged structure of the reimplant. 8. Thus, the retention of original topographic polarity did not require an integrity of the cytoarchitectonic structure of the reimplanted tectal tissue.

Action Potentials↗
PubMed2004

X-linked high myopia associated with cone dysfunction.

OBJECTIVE: Bornholm eye disease (BED) consists of X-linked high myopia, high cylinder, optic nerve hypoplasia, reduced electroretinographic flicker with abnormal photopic responses, and deuteranopia. The disease maps to chromosome Xq28 and is the first designated high-grade myopia locus (MYP1). We studied a second family from Minnesota with a similar X-linked phenotype, also of Danish descent. All affected males had protanopia instead of deuteranopia. METHODS: X chromosome genotyping, fine-point mapping, and haplotype analysis of the DNA from 22 Minnesota family individuals (8 affected males and 5 carrier females) and 6 members of the original family with BED were performed. Haplotype comparisons and mutation screening of the red-green cone pigment gene array were performed on DNA from both kindreds. RESULTS: Significant maximum logarithm of odds scores of 3.38 and 3.11 at theta = 0.0 were obtained with polymorphic microsatellite markers DXS8106 and DXYS154, respectively, in the Minnesota family. Haplotype analysis defined an interval of 34.4 cM at chromosome Xq27.3-Xq28. Affected males had a red-green pigment hybrid gene consistent with protanopia. We genotyped Xq27-28 polymorphic markers of the family with BED, and narrowed the critical interval to 6.8 cM. The haplotypes of the affected individuals were different from those of the Minnesota pedigree. Bornholm eye disease-affected individuals showed the presence of a green-red hybrid gene consistent with deuteranopia. CONCLUSIONS: Because of the close geographic origin of the 2 families, we expected affected individuals to have the same haplotype in the vicinity of the same mutation. Mapping studies, however, suggested independent mutations of the same gene. The red-green and green-red hybrid genes are common X-linked color vision defects, and thus are unrelated to the high myopia and other eye abnormalities in these 2 families. CLINICAL RELEVANCE: X-linked high myopia with possible cone dysfunction has been mapped to chromosome Xq28 with intervals of 34.4 and 6.8 centimorgan for 2 families of Danish origin.

Adolescent↗
PubMed1989

Molecular analysis of the asense gene, a member of the achaete-scute complex of Drosophila melanogaster, and its novel role in optic lobe development.

The achaete-scute complex (AS-C) comprises five genetic regions: achaete, scute (sc) alpha, lethal of sc, sc beta and sc gamma. Each region promotes the determination and positional specification of different, but partially overlapping, subsets of neural elements of Drosophila. In this work, we report a molecular characterization of the sc gamma region. It comprises 22 kb of DNA and contains two transcription units, only one of which, named asense (ase), seems involved in neurogenesis. ase encodes a protein that shares with other three AS-C proteins a domain containing a helix--loop--helix motif characteristic of a group of DNA-binding proteins. In the embryo, ase is expressed in neural precursor cells, a pattern consistent with the known requirement of sc gamma for the development of the larval nervous system. In late third-instar larvae, the gene is expressed in developing structures of the central nervous system (CNS), namely the anlagen of the optic lobes and in many cells, including neuroblasts, of the central brain and ventral ganglia. Its removal leads to anatomical defects in the adult optic lobes. This is the first demonstration of a role for the AS-C in the development of the adult CNS.

Amino Acid Sequence↗
PubMed1977

Abnormalities in the visual system of Xenopus after larval optic nerve section.

One optic nerve was cut in a series of larval Xenopus laevis; in approximately half of these the corresponding eye was also rotated. The resultant primary visual projections were mapped in the adult. Although in most cases the projections were retinotopically normal, some of them were not. These abnormal projections were consistently associated with a very thin optic nerve which reached the tectum via the oculomotor route. Animals with rotated eyes which developed retinotopically organised primary projections had a normal intertectal ipsilateral projection from the rotated eye and a rotated projection from the normal eye, thus confirming earlier findings that a process of binocular interaction determines the formation of intertectal connections. In all frogs with retinotopically abnormal primary projections the intertectal connections from the normal eye were of the type found after enucleation and those from the abnormal side were fragmentary or absent. Since the development of abnormal retinotopic patterns preceded that of intertectal connections the mechanisms of binocular interaction must have broken down in the presence of the abnormal primary projections.

Animals↗
PubMed2006

Neural network model of the primary visual cortex: from functional architecture to lateral connectivity and back.

The role of intrinsic cortical dynamics is a debatable issue. A recent optical imaging study (Kenet et al., 2003) found that activity patterns similar to orientation maps (OMs), emerge in the primary visual cortex (V1) even in the absence of sensory input, suggesting an intrinsic mechanism of OM activation. To better understand these results and shed light on the intrinsic V1 processing, we suggest a neural network model in which OMs are encoded by the intrinsic lateral connections. The proposed connectivity pattern depends on the preferred orientation and, unlike previous models, on the degree of orientation selectivity of the interconnected neurons. We prove that the network has a ring attractor composed of an approximated version of the OMs. Consequently, OMs emerge spontaneously when the network is presented with an unstructured noisy input. Simulations show that the model can be applied to experimental data and generate realistic OMs. We study a variation of the model with spatially restricted connections, and show that it gives rise to states composed of several OMs. We hypothesize that these states can represent local properties of the visual scene.

Action Potentials↗
PubMed1991

Retinal distribution of ganglion cells which project to the ipsilateral optic tectum in Bufo marinus.

The retinotectal projection in anura is mainly crossed, although a small proportion of optic axons projects to the ipsilateral tectum. Using the fluorescent carbocyanide dye, DiI, we mapped the retinal topography of ganglion cells which project to the ipsilateral tectum in adult Bufo marinus. DiI was injected into particular locations in the right tectum. After 10 days survival both the right and the left retinals were wholemounted and the number and retinal position of retrogradely filled ganglion cells were determined. The contralateral and ipsilateral cells were visuotopically distributed in the retina in the majority of experiments. However, in two cases cells were located in visuotopically disparate parts of the retina. The ipsilateral cells represented 3.7% of contralaterally projecting cells in the temporal retina, 0.1% in the nasal and dorsal retina and 0.6% of the ventral retina. The density of ipsilaterally projecting ganglion cells varied from a top of 25 cells/mm2 in the temporal retina, 9 cells/mm2 in the nasal, 3 cells/mm2 in the dorsal to 11 cells/mm2 in the ventral retina. The diversity of size and shape of retrogradely filled ganglion cells indicated that the ipsilateral population corresponded to a heterogeneous class of ganglion cell types. The functional significance of the direct ipsilateral retinotectal projection of the anuran visual system has yet to be elucidated. However, in light of the involvement of the indirect ipsilateral retinotectal projection in binocular vision, the direct pathway is likely to be associated with a retino-tecto-spinal circuit subserving postural adjustment to visually derived stimulation.

Animals↗
PubMed1988

Visual split brain and monocular deprivation in kittens: differentiation between the effects of disuse and of binocular competition in visual cortex cells.

To differentiate between the resulting effect of disuse, developmentally induced by deprivation, and the binocular competition effect on cortical cells, visual split brain was performed concurrently with monocular deprivation in kittens. In the experienced hemisphere of the split brain deprived cats (ipsilaterally to the non-deprived eye), there were twice as many visually responsive cortical cells than found in their inexperienced hemisphere (ipsilaterally to the deprived eye); however, these cells were equal in number to that found in the split brain controls. In the monocularly deprived control cats a relation of 3.2 was found between cells driven by the non-deprived and the deprived eye. Visual disuse, therefore, resulting from monocular deprivation, affects cortical cells under complete absence of binocular competition but is greatly enhanced by the latter.

Animals↗
PubMed1994

Mice deficient for the myelin-associated glycoprotein show subtle abnormalities in myelin.

Using homologous recombination in embryonic stem cells, we have generated mice with a null mutation in the gene encoding the myelin-associated glycoprotein (MAG), a recognition molecule implicated in myelin formation. MAG-deficient mice appeared normal in motor coordination and spatial learning tasks. Normal myelin structure and nerve conduction in the PNS, with N-CAM overexpression at sites normally expressing MAG, suggested compensatory mechanisms. In the CNS, the onset of myelination was delayed, and subtle morphological abnormalities were detected in that the content of oligodendrocyte cytoplasm at the inner aspect of most myelin sheaths was reduced and that some axons were surrounded by two or more myelin sheaths. These observations suggest that MAG participates in the formation of the periaxonal cytoplasmic collar of oligodendrocytes and in the recognition between oligodendrocyte processes and axons.

Animals↗
PubMed2004

Analysis of the interaction of a hybrid system consisting of bovine adrenodoxin reductase and flavodoxin from the cyanobacterium Anabaena PCC 7119.

The mitochondrial steroid-hydroxylating system in vertebrates and the NADPH producing electron transfer chain in photosynthetic organisms contain structurally and functionally similar components. Examination of a potential hybrid reconstitution of the electron transfer chain between different components of both systems could help to improve our knowledge on protein-protein interaction and subsequent electron transfer. Here we analyzed the interaction between bovine adrenodoxin reductase and flavodoxin from the cyanobacterium Anabaena PCC 7119. Optical biosensor as well as steady state and fast kinetic experiments showed their ability to form distinct productive complexes. Compared with the corresponding physiological systems the electron transfer is rather slow, probably due to the lack of specificity at the interaction surface.

Animals↗
PubMed2005

Sensitivity of ex situ and in situ spectral surface plasmon resonance sensors in the analysis of protein arrays.

We have investigated the sensitivity of ex situ (analysis under air condition) and in situ (analysis under liquid condition) spectral SPR sensors, which were self-constructed with fiber optic spectrometers. The sensitivity of SPR sensors was analyzed in the wavelength range of 550-780 nm by the interactions of streptavidin and biotinylated IgG, and the sensitivity was dependent on the wavelength of measurements. The sensitivity of an ex situ SPR sensor operated at the long wavelength range from 712 nm was approximately 2.6 times higher than that at the short wavelength range from 571 nm. In addition, the sensitivity of an ex situ spectral SPR sensor was about twice as high as that of an in situ spectral SPR sensor for the same resonance wavelength range. This was interpreted in that the difference in sensitivity between two SPR sensors was significantly caused by the evanescent field intensity at the metal/dielectric interface. Thus, it was suggested that ex situ spectral SPR sensors operated at the long wavelength range are sensitive biosensors for the high-throughput analysis of protein interactions on protein arrays.

Biosensing Techniques↗
PubMed2005

The high and middle molecular weight neurofilament subunits regulate the association of neurofilaments with kinesin: inhibition by phosphorylation of the high molecular weight subunit.

Kinesin participates in axonal transport of neurofilaments (NFs), but the mode by which they attach to kinesin is unclear. We compared the association of NFs with kinesin in mice expressing or lacking NF-H or NF-M. In normal and M-/- mice, the leading edge of metabolically labeled NF subunits was selectively co-precipitated with kinesin. By contrast, the entire wave of radiolabeled subunits co-precipitated with kinesin in H-/- mice. Similar bulk levels of NFs co-precipitated with kinesin from normal and H-/- mice, but reduced levels co-precipitated from M-/- mice. These data suggest that both NF-H and NF-M regulate the association of NFs with kinesin. They further indicate that phosphorylation of NF-H dissociates NFs from kinesin and provides a mechanism by which NF-H phosphorylation can contribute to the slowing of NF axonal transport.

Animals↗