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 865 records · Page 48Linked to original sources
PubMedDate not supplied

Organization of retinal ganglion cell axons in the optic fiber layer and nerve of fetal ferrets.

Previous authors have hypothesized that retinotopic projections may be influenced by 'preordering' of the axons as they grow towards their targets. In some nonmammalian species, axons are reorganized at or near the optic nerve head to establish a retinotopic order. Data are ambiguous concerning the retinotopy of the mammalian retinal nerve fiber layer and whether fibers become reorganized at the optic nerve head. We have examined this question in fetal and newborn ferrets (Mustela putorius furo) by comparing the arrangement of axons in the retinal nerve fiber layer with that in the optic nerve. Dil or DiA crystals were implanted into fixed tissue in the innermost layers of the retinal periphery, or at a location midway between the periphery and the optic nerve head. Fluorescence labelling was examined in 100-200 microns Vibratome sections, or the eyecup and nerve were photooxidized and 1-2 microns longitudinal or transverse sections were examined. Regardless of fetal age, eccentricity or quadrant of the implant site, a segregation of labelled peripheral axons from unlabelled central ones was not detected within the nerve fiber layer. Axons coursed into the nerve head along the margin of their retinal quadrant of origin, often entering the optic nerve as a radial wedge, thus preserving a rough map of retinal circumference. However, peripheral axons were in no way restricted to the peripheral (nor central) portions of the nerve head or nerve, indicating that the optic axons do not establish a map of retinal eccentricity. Our results demonstrate that (1) the nerve fiber layer is retinotopic only with respect to circumferential position and (2) optic axons are not actively reorganized to establish a retinotopic ordering at the nerve head. The present results suggest that any degree of order present within the optic nerve is a passive consequence of combining the fascicles of the retinal nerve fiber layer; optic axons are not instructed to establish, nor constrained to maintain, a retinotopic order within the optic nerve.

Animals↗
PubMedDate not supplied

Near-field optical analysis of living cells in vitro.

Near-field optical analysis (NOA) provides morphological nanoscale mappings of living cells in liquid cell culture media and nondestructive insight into cell functionality. Here we show for the first time the performance of NOA in imaging living cells. Unlabeled human endothelial cells attached to polished titanium disks were analyzed with hydrophobically coated optical biosensors mounted to a near-field scanning optical microscope (NSOM). Biosensors and titanium substrates could be simply implemented in standard NSOM and high-throughput NOA.

Endothelium↗
PubMed2003

Analysis of macular volume in normal and glaucomatous eyes using optical coherence tomography.

PURPOSE: To evaluate macular volume in normal and glaucomatous eyes using optical coherence tomography (OCT). DESIGN: Case control study. METHOD: The authors assessed 272 eyes of 164 subjects as part of an institutional study at New England Eye Center in Boston, Massachusetts; 202 eyes were in the study group and 70 eyes in the control group. Eyes were categorized as normal (70 eyes of 43 subjects), glaucoma suspect (70 eyes of 44 subjects), early glaucoma (70 eyes of 47 subjects), or advanced glaucoma (62 eyes of 43 subjects). Subjects underwent analysis with the commercially available OCT1 unit. Optical coherence tomography macular neurosensory retinal thickness maps were used to calculate macular volume for comparison to Humphrey visual field testing, intraocular pressure measurement, and stereo biomicroscopy of the optic nerve head and nerve fiber layer. RESULTS: Using repeated measures regression, macular volume in normal (2.37 +/- 0.11 mm(3)) glaucoma suspect (2.33 +/- 0.16 mm(3)), and early glaucoma eyes (2.27 +/- 0.13 mm(3)) was significantly greater than in eyes with advanced glaucoma (2.12 +/- 0.23 mm(3), P =.0001, P =.0001, and P =.0008, respectively). Macular volume in normal eyes was significantly greater than in early glaucoma eyes (P =.01). CONCLUSIONS: Optical coherence tomography retinal macular volume correlates with known structural defects of glaucoma, providing a potential objective and quantitative parameter for evaluation. Our data show a significant difference in macular volume between normal, glaucoma suspect, and early glaucoma eyes, compared with advanced glaucomatous eyes as well as between normal and early glaucomatous eyes. This correlates with a trend of decreasing macular volume in eyes with more advanced disease.

Adolescent↗
PubMed2003

Allatostatin-like immunoreactivity in the optic lobe of the fly Sarcophaga bullata.

An antiserum against Diploptera allastostain 1 (Dip-AST1) was used to map the distribution of allatostain containing neurons in the optic lobes of the fly Saccrophaga bullata. Strongly immunoreacting neurons were found in two areas of the optic ganglia, namely, the medulla and the area between medulla and lobula. These cells were generally interneurons arborizing the base of the medulla. The positive reaction of specific populations of the optic lobe neurons against allatostain antiserum suggests some role for this neuropeptide in the visual physiology of the fly.

Animals↗
PubMed2004

Nano-optics with single quantum systems.

This paper reviews the recent progress in using single quantum systems, here mainly single fluorescent molecules, as local probes for nano-optical field distributions. We start by discussing the role of the absorption cross-section for the spatial resolution attainable in such experiments and its behaviour for different environmental conditions. It is shown that the spatial distribution of field components in a high-numerical aperture laser focus can be mapped with high precision using single fluorescent molecules embedded in a thin polymer film on glass. With this proof-of-principle experiment as a starting point, the possibility of mapping strongly confined and enhanced nano-optical fields close to material structures, e.g. sharp metal tips, is discussed. The mapping of the spatial distribution of the enhanced field at an etched gold tip using a single molecule is presented as an example. Energy transfer effects and quenching are identified as possible artefacts in this context. Finally, it is demonstrated that the local quenching at a sharp metal structure nevertheless can be exploited as a novel contrast mechanism for ultrahigh-resolution optical microscopy with single-molecule sensitivity.

Fluorescence Resonance Energy Transfer↗
PubMed2001

Fine-scale organization of SI (area 3b) in the squirrel monkey revealed with intrinsic optical imaging.

Optical imaging of intrinsic cortical activity was used to study the somatotopic map and the representation of pressure, flutter, and vibration in area 3b of the squirrel monkey (Saimiri sciureus) cortex under pentothal or isoflurane anesthesia. The representation of the fingerpads in primary somatosensory cortex was investigated by stimulating the glabrous skin of distal fingerpads (D1-D5) with Teflon probes (3-mm diam) attached through an armature to force feedback-controlled torque motors. Under pentothal anesthesia, intrinsic signal maps in area 3b obtained in response to stimulation (trapezoidal indentation) of individual fingerpads showed focal activations. These activations (ranging from 0.5 to 1.0 mm) were discrete and exhibited minimal overlap between adjacent fingerpad representations. Consistent with previously published maps, a somatotopic representation of the fingerpads was observed with an orderly medial to lateral progression from the D5 to D1 fingerpads. Under isoflurane anesthesia, general topography was still maintained, but the representation of fingerpads on adjacent fingers had higher degrees of overlap than with pentothal anesthesia. Multi- and single-unit recordings in the activation zones confirmed the somatotopic maps. To examine preferential inputs from slowly adapting type I (SA) and rapidly adapting type I (RA) and type II (PC) mechanoreceptors, we applied stimuli consisting of sinusoidal indentations that produce sensations of pressure (1 Hz), flutter (30 Hz), and vibration (200 Hz). Under pentothal anesthesia, activation patterns to these different stimuli were focal and coincided on the cortex. Under isoflurane, activation zones from pressure, flutter, and vibratory stimuli differed in size and shape and often contained multiple foci, although overall topography was maintained. Subtraction and vector maps revealed cortical areas (approximate 250-microm diam) that were preferentially activated by the sensations of pressure, flutter, and vibration. Multi- and single-unit recordings aided in the interpretation of the imaging maps. In conclusion, the cortical signals observed with intrinsic signal optical imaging delineated a somatotopic organization of area 3b and revealed different topographical cortical activation patterns for pressure, flutter, and vibratory stimuli. These patterns were dependent on anesthesia type. Possible relationships of these anesthesia effects to somatosensory cortical plasticity are discussed.

Anesthesia↗
PubMed1998

Optical CT reconstruction of 3D dose distributions using the ferrous-benzoic-xylenol (FBX) gel dosimeter.

In recent years, magnetic-resonance imaging of gelatin doped with the Fricke solution has been applied to the direct measurement of three-dimensional (3D) radiation dose distributions. However, the 3D dose distribution can also be imaged more economically and efficiently using the method of optical absorption computed tomography. This is accomplished by first preparing a gelatin matrix containing a radiochromic dye and mapping the radiation-induced local change in the optical absorption coefficient. Ferrous-Benzoic-Xylenol (FBX) was the dye of choice for this investigation. The complex formed by Fe3+ and xylenol orange exhibits a linear change in optical attenuation (cm-1) with radiation dose in the range between 0 and 1000 cGy, and the local concentration of this complex can be probed using a green laser light (lambda = 543.5 nm). An optical computed tomography (CT) scanner was constructed analogous to a first-generation x-ray CT scanner, using a He-Ne laser, photodiodes, and rotation-translation stages controlled by a personal computer. The optical CT scanner itself can reconstruct attenuation coefficients to a baseline accuracy of < 2% while yielding dose images accurate to within 5% when other uncertainties are taken into account. Optical tomography is complicated by the reflection and refraction of light rays in the phantom materials, producing a blind spot in the transmission profiles which, results in a significant dose artifact in the reconstructed images. In this report we develop corrections used to reduce this artifact and yield accurate dosimetric maps. We also report the chemical reaction kinetics, the dose sensitivity and spatial resolution (< 1 mm3) obtained by optical absorption computed tomography. The article concludes with sample dose distributions produced by "cross-field" 6 MV x-ray beams, including a radiosurgery example.

Benzoic Acid↗
PubMed1999

Geometrical and topological relationships between multiple functional maps in cat primary visual cortex.

The mammalian striate cortex is organized such that the receptive field properties of neighboring neurons change gradually across the cortical surface, forming so-called cortical maps. The presence of such maps has been demonstrated in different species of mammals for several parameters characterizing the visual space: retinotopy, ocular dominance, orientation, direction of motion and spatial frequency. In this study we used the optical imaging of intrinsic signals to simultaneously record the multiple functional maps in the same animal in order to obtain a comprehensive set of rules that govern mutual dependencies among the functional maps. Our results indicate that while orientation, direction and ocular dominance are represented on the cortex in a mutually dependent manner, the representation of spatial frequency is independent of the other types of cortical representations. The presence and/or absence of mutual dependence among the multiple functional maps are suggested to provide an important clue for the understanding of the development of visual cortical information representation in neonatal animals.

Animals↗
PubMed2005

Spontaneous patterned retinal activity and the refinement of retinal projections.

A characteristic feature of sensory circuits is the existence of orderly connections that represent maps of sensory space. A major research focus in developmental neurobiology is to elucidate the relative contributions of neural activity and guidance molecules in sensory map formation. Two model systems for addressing map formation are the retinotopic map formed by retinal projections to the superior colliculus (SC) (or its non-mammalian homolog, the optic tectum (OT)), and the eye-specific map formed by retinal projections to the lateral geniculate nucleus of the thalamus. In mammals, a substantial portion of retinotopic and eye-specific refinement of retinal axons occurs before vision is possible, but at a time when there is a robust, patterned spontaneous retinal activity called retinal waves. Though complete blockade of retinal activity disrupts normal map refinement, attempts at more refined perturbations, such as pharmacological and genetic manipulations that alter features of retinal waves critical for map refinement, remain controversial. Here we review: (1) the mechanisms that underlie the generation of retinal waves; (2) recent experiments that have investigated a role for guidance molecules and retinal activity in map refinement; and (3) experiments that have implicated various signaling cascades, both in retinal ganglion cells (RGCs) and their post-synaptic targets, in map refinement. It is likely that an understanding of retinal activity, guidance molecules, downstream signaling cascades, and the interactions between these biological systems will be critical to elucidating the mechanisms of sensory map formation.

Animals↗
PubMed1983

The visuotectal projection following translocation of grafts within an optic tectum in the goldfish.

Rectangular grafts were translocated between the rostral and caudal tectum in adult goldfish. In some animals the optic nerve was also cut. After periods ranging from 161 to 378 days the retinotectal projections were mapped. The results showed that translocation of tectal grafts is followed by translocation of the corresponding part of the visuotectal map. In many cases the visual field positions projecting to points in the region between the grafts were abnormal and in some cases intercalated field positions were found across the borders between grafted and normal tissue. The results are taken as strong evidence for the existence of affinity labels on the tectum and their importance in the restoration of the retinotectal projection.

Animals↗
PubMed1991

Retinal projections in the freshwater butterfly fish, Pantodon buchholzi (Osteoglossoidei). I. Cytoarchitectonic analysis and primary visual pathways.

The freshwater butterfly fish, Pantodon buchholzi, is a member of the most primitive radiation of teleosts. The retinofugal projections were studied in this fish with autoradiographic and horseradish peroxidase (HRP) methods, and the cytoarchitecture of the retinorecipient regions in the diencephalon and pretectum was analyzed with Bodian-, cresylecht-violet- and acetylcholinesterase-reacted sections. The rostral diencephalon of Pantodon contains a large retinorecipient nucleus, not previously identified in any other fish, i.e. nucleus rostrolateralis. Other nuclei that are described correspond to those previously recognized in other species. The majority of retinorecipient nuclei are positive for acetylcholinesterase, particularly those in the pretectum, as has been found in other species of teleosts. Most of the retinofugal fibers decussate in the optic chiasm. Some fibers project via the axial optic tract to preoptic nuclei and a region in the rostral hypothalamus. Fibers leave the medial optic tract to terminate in nucleus rostrolateralis and in dorsal and ventral thalamic nuclei, accessory optic and tubercular nuclei, periventricular and central pretectal nuclei, and sparsely in the deep tectal fascicle and terminal field. Dorsal optic tract fibers project to the dorsal accessory optic nucleus, superficial and central pretectal nuclei, and superficial and deep tectal layers. Ventral optic tract fibers project to the superficial pretectum, accessory optic nuclei, posterior tuberculum, nucleus corticalis in the central pretectum, and superficial tectal layer. Fibers that remain in the ipsilateral optic tract project to most of the targets reached by contralaterally projecting fibers. A few fibers in the contralateral medial optic tract redecussate via the posterior commissure to reach the ipsilateral periventricular pretectum. No labeled retinopetal cells caudal to the olfactory bulb were identified in any of the HRP cases.

Acetylcholinesterase↗
PubMed1985

The antidromic activation of tectal neurons by electrical stimuli applied to the caudal medulla oblongata in the toad, Bufo bufo L.

In order to specify the tectal projection to the bulbar/spinal regions, the antidromic responses of the physiologically identified tectal neurons as well as the gross antidromic field responses in the optic tectum to electrical stimuli applied to the caudal medulla were examined in the paralyzed common toad, Bufo bufo. The antidromic field potential was recorded in the optic tectum in response to electrical stimuli applied to the ventral paramedian portion of the contralateral caudal medulla (where the crossed tecto-spinal pathway of Rubinson (1968) and Lázár (1969) runs), but generally not when they were applied to various parts of the ipsilateral caudal medulla. The antidromic field potential was largest at the superficial part of Layer 6 or at the border between Layers 6 and 7 of the optic tectum, indicating that neurons in these layers project to the contralateral caudal medulla. Mapping experiments of the antidromic field potential over the optic tectum showed that the antidromic field potential was recorded mainly in the lateral part of it, indicating that this part of the optic tectum is the main source of projection neurons to the contralateral caudal medulla. Various classes of tectal neurons as well as retinal ganglion neurons were identified from the characteristics of the response properties to moving visual stimuli and the properties of the receptive fields. Of these, the Class T1, T2, T3, T4, T5(1), T5(2), T5(3), and T5(4) tectal neurons were activated antidromically by stimuli applied to the contralateral caudal medulla. Only a limited proportion of the Class T5(1) neurons was activated antidromically by stimuli applied to the ipsilateral caudal medulla. On the other hand, the Class T7 and T8 neurons, as well as the Class R2, R3, and R4 retinal neurons, were not activated antidromically by stimuli applied to the caudal medulla of either side. These results suggest a possibility that these tectal neurons which project to the medullary regions form the substrate of the sensorimotor interfacing and contribute to the initiation or coordination of the visually guided behavior, such as prey-catching.

Animals↗
PubMed2000

Topographic order of retinofugal axons in a marsupial: implications for map formation in visual nuclei.

We studied axon order in the primary visual pathway and in nine retinorecipient nuclei of a small marsupial, the fat-tailed dunnart (Sminthopsis crassicaudata) using animals at postnatal day (P) 40 and P80. Dorsal, ventral, nasal, and temporal axons enter the optic nerve true to their retinal origin being respectively dorsal, ventral, medial, and lateral; the arrangement is retained to the chiasm. Dorsal and ventral axons maintain their respective locations within the chiasm but at the base of the contralateral optic tract undergo a 180 degrees axial rotation, thus reversing the dorsoventral axis with respect to the retina. The alignment is conserved along the optic tract with dorsal and ventral axons mapping directly into appropriate quadrants of each retinorecipient nucleus. Nasal and temporal axons remain segregated as they decussate and lie respectively superficially and deep along the optic tract but with some intermingling. Within each retinorecipient nucleus, the nasotemporal axis is clearly demarcated, being represented in either a rostrocaudal (ventral and dorsal lateral geniculate nuclei; lateral posterior, dorsal terminal, and pretectal nuclei) or caudorostral (medial terminal and caudal pretectal nuclei, intergeniculate nucleus and superior colliculus) direction. The results imply that the dorsoventral axis in the retinorecipient nuclei could be due to preordering within the pathway, whereas the nasotemporal axis is determined by target-based cues. Moreover, cues for the orientation of the nasotemporal axis within retinorecipient nuclei must be localised within individual nuclei rather than as a single organiser, as previously envisaged (Chung and Cooke [1978] Proc. R. Soc. Lond. B. 210:335-373).

Animals↗
PubMed1999

Integral Field Spectroscopy of Markarian 273: Mapping High-Velocity Gas Flows and an Off-Nucleus Seyfert 2 Nebula.

Integral field optical spectroscopy with the INTEGRAL fiber-based system is used to map the extended ionized regions and gas flows in Mrk 273, one of the closest ultraluminous infrared galaxies. The Hbeta and [O iii] lambda5007 maps show the presence of two distinct regions separated by 4&arcsec; (3.1 kpc) along position angle (P.A.) 240 degrees. The northeastern region coincides with the optical nucleus of the galaxy and shows the spectral characteristics of LINERs. The southwestern region is dominated by [O iii] emission and is classified as a Seyfert 2. Therefore, in the optical, Mrk 273 is an ultraluminous infrared galaxy with a LINER nucleus and an extended off-nucleus Seyfert 2 nebula. The kinematics of the [O iii] ionized gas shows (1) the presence of highly disturbed gas in the regions around the LINER nucleus, (2) a high-velocity gas flow with a peak-to-peak amplitude of 2.4x103 km s-1, and (3) quiescent gas in the outer regions (at 3 kpc). We hypothesize that the high-velocity flow is the starburst-driven superwind generated in an optically obscured nuclear starburst and that the quiescent gas is directly ionized by a nuclear source, similar to the ionization cones typically seen in Seyfert galaxies.

Journal Article↗
PubMed1994

Contour mapping of spectacle lenses.

The measurement of spectacle lenses by conventional focimeters and automated focimeters assesses only a small region of the lens, and only the power and related data at that point are indicated. In this paper, two methods based on optical Fourier filtering and optical correlation are suggested for contour-mapping the deviations of a spectacle lens over its whole aperture. The fringe pattern appearing on the lens image depicts vividly the characteristics of the tested lens. All the related data are qualitatively seen at a glance and can be calculated from the fringe distribution. Furthermore, the optical processing of the fringes by defocusing is described; thus, the fringes can be continuously changed by shifting the illuminating point source or mask. The shift indicates the spherical power needed to decrease or increase the lens fringes. In addition, a fringe-reading technique is suggested by counting the number of the fringes within a reticle ring. Therefore, the sphere power, cylinder power, cylinder axis, prism power, and prism orientation can be obtained from the reading of the fringes, the shift position, or their combination with a high accuracy. The methods are suitable not only to sphere, spherocylinder, and prism lenses but also to multifocus and progressive power lenses. The suggestion provides a practical way to measure spectacle lenses over the whole aperture.

Eyeglasses↗
PubMed2005

Optical tomography with ultrasound localization: initial clinical results and technical challenges.

Optical tomography with ultrasound localization utilizes co-registered ultrasound lesion structure information to guide optical imaging reconstruction. A hand-held probe consisting of a commercial ultrasound transducer and near infrared optical imaging sensors was used to simultaneously acquire ultrasound images and optical measurements. A dual-mesh scheme was used to map the ultrasound-visible lesions to finer-grid lesion regions and coarser-grid background regions for optical imaging reconstruction. As a result, optical imaging reconstruction was well-conditioned for inverse mapping of lesion hemoglobin concentration and blood oxygen saturation. Initial clinical results have shown that early stage invasive cancers may be distinguished by a two-fold greater total hemoglobin concentration compared with fibroadenomas and other benign lesions. Initial results of advanced cancers have shown that the hemoglobin distribution is highly distorted and heterogeneous and the distorted distributions correlate with histological microvessel density counts and could be used to assess chemotherapy response.

Adenocarcinoma↗