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PubMed2005

Hyperspectral mapping-combining cathodoluminescence and X-ray collection in an electron microprobe.

An optical spectrometer has been integrated into a JEOL 8900R electron microprobe, which allows simultaneous collection of light, X-ray, and electron signals. The cathodoluminescence signal is collected from a monocular eyepiece, which is integrated into the electron optics of the electron microprobe. The optical acquisition is synchronized with the stage motion. X-ray lines of major elements are collected using an energy dispersive spectrometer, X-ray lines of minor elements are collected using wavelength dispersive spectrometers, and the secondary and backscattered electron signals are collected using standard detectors. In mapping mode of operation the different signals are collected at each pixel with map sizes typically ranging from 1 million to 10 million pixels. This represents a significant amount of data from which the major correlations and associations in the map can be determined. Summing over a small number of channels and examining only a subset of the complete wavelength range are the strategies that have been developed to reduce the size of the data handled. The application of this mapping technique is demonstrated with two examples, zircons and refractory bricks. Zircons with various degrees of metamictization have been characterized, and inclusions differentiated using a combination of cathodoluminescence and X-ray maps. Examination of refractory bricks reveals subtle chemical changes in the spinel grains.

Electron Probe Microanalysis↗
PubMed2004

Measuring optical properties of an eye lens using magnetic resonance imaging.

We compare the focal lengths of porcine lenses measured optically and by using a novel MRI technique. The geometric properties of the lenses were also measured and compared. The MRI technique exploits the dependence of both the lens refractive index and relaxation rates on the local protein concentration. By measuring the refractive index and corresponding values of R2 (=1/T2) for samples of lens homogenates with different protein concentrations, the dependence of refractive index on R2 was determined empirically. R2 maps, constructed from monoexponential fits to multiecho images of a slice through the lens containing the optical axis, were converted to refractive index maps using this relationship. A simulated ray trace through the refractive index map provided an estimate of lens focal length that was compared to a direct optical measurement of focal length using a laser ray-tracing method. It was found that the mean focal lengths estimated from the two techniques agreed within experimental uncertainty. The refractive index profile along the optical axis was found to be well described by a simple function of the form n=n0 + n1 x ra where r is the (normalized) lens radius.

Animals↗
PubMed1983

The development and restriction of the ipsilateral retinofugal projection in the chick.

Although it is generally believed that the central projections of the retina in birds are entirely crossed, using wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) as an anterograde tracer, we have found that in normal posthatched chicks there is a small ipsilateral retinofugal projection to the diencephalon and midbrain. Most of the ipsilateral fibers appear to be directed to the lateral anterior and dorsolateral anterior nuclei of the thalamus, to the pretectal region, and to the ectomammillary nucleus and the adjoining nucleus externus. Even in the best preparations the numbers of ipsilateral fibers are so small that it is hardly surprising that they have been overlooked in previous axonal degeneration and autoradiographic experiments. A significantly larger ipsilateral retinal projection develops during the second week of incubation. The ipsilaterally directed fibers can be first seen on the fifth day of incubation and their numbers appear to increase until about embryonic day 12. At this stage the projection involves substantially more fibers than at hatching and is also more extensive in its distribution; in fact, in its general organization (but not its size) it closely parallels the normal crossed retinofugal system, contributing fibers to essentially all the primary visual relay nuclei in the diencephalon and midbrain and to much of the optic tectum, where the densest projection is to its caudomedial aspect. During the second week of incubation there is also a small number of retinal fibers, which after crossing in the optic chiasm, recross the midline in the posterior and tectal commissures (and also in the tectal roof plate), before ending in the pretectal region of the ipsilateral side. In addition, there is a markedly aberrant projection from the retina into the contralateral optic nerve. Most of the ipsilateral retinal fibers are eliminated between the twelfth and sixteenth days of incubation, and by day 17 the ipsilateral projection is reduced to its mature form. The progressive reduction in the ipsilateral projection occurs at a time when it is known (from other studies) that there is an appreciable loss of retinal ganglion cells; but whether the reduction is due to neuronal death or to the selective elimination of ipsilateral axon collaterals remains to be determined. The existence of a significant ipsilateral retinofugal component early in development, probably accounts, in part, for the distinctive and persistent ipsilateral projection that occurs if one eye is removed during the first few days of incubation.

Animals↗
PubMed1985

Apparent movement of optic terminals out of a local postsynaptically blocked region in goldfish optic tectum.

In goldfish tectum, alpha-bungarotoxin (alpha BTX) blocks postsynaptically generated field potentials elicited by either photic or electrical stimulation, but leaves presynaptic activity unaffected. To assess the chronic effects of blocking transmission on synaptic stability, small restricted areas of synaptic block were created by slow, low-pressure microinjection of toxin-Ringer's solution from a micropipette. Local transmission was blocked, but field potentials outside the injected region were unchanged. Radioautography of 125I-alpha BTX demonstrated that 6 days postinjection it was still highly localized and concentrated in discrete synaptic laminae of the tectal neuropil, in agreement with its known tight binding in goldfish brain (18). Electrophysiological maps made 6-8 days postinjection showed that few if any optic terminals could be recorded in the toxin-blocked zone, but there was no scotoma in the visual field. Terminals with receptive fields that would normally have corresponded to the region of injection were instead recorded from surrounding tectal areas. Since the normal units were also recorded there, this produced very large multiunit receptive fields. Apparently the optic terminals within the toxin-blocked area moved outward and innervated neighboring areas. In a minority of cases, no silent areas were noted and only the enlarged multiunit receptive fields were seen in the injection zone. All tecta injected with alpha BTX, but none injected with Ringer's, showed these disturbances in the map at the treated area at 6-8 days postinjection. By 2-3 wk, the maps in the alpha BTX-injected tecta had returned to normal. There were no silent areas and no enlarged receptive fields. The movement of the optic arbors was shown to be dependent on activity in the optic fibers. In fish receiving intraocular injections of tetrodotoxin (TTX) for the first 4-6 days, no changes were seen in the retinotectal maps recorded after the effects of the TTX wore off. When the entire surface of the tectum was blocked with multiple injections of alpha BTX, normal maps were recorded at 6-8 days postinjection. Thus in order to produce movements in optic terminals, the fibers require activity and an opportunity to make effective synapses in a nearby zone.

Animals↗
PubMed1993

Sources of electric brain activity: intracortical current dipoles.

Intracortical evoked potentials after electrical stimulation of the optic nerve were simultaneously recorded from the different layers of the rabbit's visual cortex. The averaged potentials were subjected to current source density analyses. The results show that the first event after the stimulus is a current sink in layer VI according to the excitatory terminations of the specific afferent fibres of the geniculate body. Since the largest part of the specific afferents terminates in layers IV and V, the sink in those layers may be due to excitatory synaptic events there. The corresponding current sources are situated in the upper layers and are most probably passive sources due to the active sinks. This example demonstrates that the generation of intracortical electric potentials can be explained by vertically oriented current dipoles according to the anatomical peculiarities.

Animals↗
PubMed2000

Functional specificity of callosal connections in tree shrew striate cortex.

Although callosal connections have been shown to link extensive regions of primary visual cortex, the distribution of these connections with respect to the map of visual space and the map of orientation preference remains unclear. Here we combine optical imaging of intrinsic signals with injection of fluorescent microspheres to assess the functional specificity of callosal connections in the tree shrew. By imaging both hemispheres simultaneously while presenting a series of spatially restricted stimuli, we find that a substantial region of visual space is represented bilaterally. Each hemisphere includes a representation of the ipsilateral visual field that is highly compressed relative to that of the contralateral visual field and is most extensive in the lower visual field, where approximately 30(o) of central visual space are represented bilaterally. Callosal connections extend throughout the region of bilateral representation but terminate in a spatially restricted manner that links visuotopically corresponding sites in the two hemispheres. In contrast, callosal connections appear to terminate without regard for the map of orientation preference, showing little sign of the orientation-specific modular and axial specificity that is characteristic of long-range horizontal connections. By coordinating the activity in the two hemispheres in a way that preserves nearest neighbor relationships, callosal connections may best be viewed as elements of local circuits that operate within a single bilateral representation of visual space.

Animals↗
PubMed2002

Retinal topography and thickness mapping in atrophic age related macular degeneration.

AIM: To determine the relation between alterations in the retinal topography and thickness, visual acuity, and retinal pigment epithelium hypopigmentation in atrophic age related macular degeneration (AMD). METHODS: 22 patients, mean age 74 (SD 8) years, with atrophic AMD were recruited. An optical imaging system based on the retinal thickness analyser (RTA) was applied to generate a series of 20 optical section images that encompass 2 mm x 2 mm retinal areas. The optical section images were digitised and analysed to provide topographic maps of the vitreoretinal and chorioretinal surfaces and the retinal thickness. Vitreoretinal and chorioretinal surface elevations and retinal thickness were determined. RESULTS: Variation in the vitreoretinal surface height was moderately correlated with visual acuity (r = -0.4; p = 0.03; n = 22). Increase in variation of chorioretinal surface height was correlated with decrease in visual acuity (r = -0.5; p = 0.01; n = 22). The retinal thickness was not associated with visual acuity (r = 0.2; p = 0.2; n=22). Relative height of the vitreoretinal surface in eyes with retinal pigment epithelium (RPE) hypopigmentation was significantly less than eyes without RPE hypopigmentation (p = 0.005). Eyes with and without RPE hypopigmentation had a similar relative height of the chorioretinal surface (p = 0.4). Retinal thickness in eyes with RPE hypopigmentation was less than in eyes without RPE hypopigmentation (p = 0.04). CONCLUSION: Mapping of chorioretinal and vitreoretinal topography and retinal thickness provides objective and quantitative measurements of retinal structural abnormalities and shows promise as an adjunct for the evaluation of retinal structural changes due to AMD.

Aged↗
PubMed1983

Laminar organization of tree shrew dorsal lateral geniculate nucleus.

This study investigated the organization of the dorsal lateral geniculate nucleus (LGN) of the tree shrew (Tupaia glis) using both microelectrode recording and anatomical techniques. The tree shrew LGN contains approximately 100,000 cells, of which 20% are in layers 2 and 6. These two layers receive input from the ipsilateral eye. The topography of the tree shrew LGN was delineated by taking systematic penetrations through the structure. Examination of the organization of the LGN laminae showed the following: in layer 1 (the lamina next to the optic tract) a mixture of on-center, off-center and on-off center cells was found; the majority of these cells responded transiently to visual stimuli and they had slightly longer conduction latencies than did cells in the other laminae. On-center and off-center cells in laminae 2-6 were sharply segregated: layers 2, 3, and 4 contained off-center cells and layers 5 and 6 contained on-center cells. Most of the cells in laminae 2-6 responded in a sustained manner to visual stimuli. These results suggest that one function of the LGN lamina is to group cells into various classes. Such grouping has now been shown to occur partially or completely for 1) eye of origin, 2) cell types characterized as on-center and off-center, and 3) cell types characterized as producing transient and sustained responses. The nature and degree of laminar specificity, however, varies considerably from species to species.

Animals↗
PubMed2003

Applications and limitations of perfusion-dependent functional brain mapping for neurosurgical guidance.

Perfusion-dependent brain mapping modalities, such as functional magnetic resonance imaging, positron emission tomography, and optical imaging of intrinsic signals, have become increasingly popular for neurosurgical guidance because they offer a relatively rapid and noninvasive means of mapping brain function. These modalities are unique because they rely on perfusion-related signals that are coupled with neuronal activity to map the brain instead of measuring electrophysiological responses. They consequently present unique challenges to the clinician in terms of understanding the significance and limitations of the maps they produce. In particular, one must be aware of limitations of the modalities with respect to spatial specificity, sensitivity, and reliability of these maps and how the presence of intracranial lesions may further complicate these issues. The authors review the evolution, interpretation, and limitations of perfusion-based brain mapping techniques, with special attention to clinical implications of the brain maps.

Brain Diseases↗
PubMed2005

Retinotopic axis specificity and selective clustering of feedback projections from V2 to V1 in the owl monkey.

Cortical maps and feedback connections are ubiquitous features of the visual cerebral cortex. The role of the feedback connections, however, is unclear. This study was aimed at revealing possible organizational relationships between the feedback projections from area V2 and the functional maps of orientation and retinotopy in area V1. Optical imaging of intrinsic signals was combined with cytochrome oxidase histochemistry and connectional anatomy in owl monkeys. Tracer injections were administered at orientation-selective domains in regions of pale and thick cytochrome oxidase stripes adjacent to the border between these stripes. The feedback projections from V2 were found to be more diffuse than the intrinsic horizontal connections within V1, but they nevertheless demonstrated clustering. The clusters of feedback axons projected preferentially to interblob cytochrome oxidase regions. The distribution of preferred orientations of the recipient domains in V1 was broad but appeared biased toward values similar to the preferred orientation of the projecting cells in V2. The global spatial distribution of the feedback projections in V1 was anisotropic. The major axis of anisotropy was systematically parallel to a retinotopic axis in V1 corresponding to the preferred orientation of the cells of origin in V2. We conclude that the feedback connections from V2 to V1 might play a role in enhancing the response in V1 to collinear contour elements.

Animals↗
PubMed1994

Postmortem anatomy from cryosectioned whole human brain.

A system of histologic and digital processing protocols are presented for the acquisition of high-resolution digital imagery from postmortem cryosectioned whole human brain and head for computer-based 3-dimensional (3D) representation and visualization. We designed and evaluated several protocols for optimal preparation of frozen specimens including fixation, decalcification, cryoprotection, freezing and sectioning procedures. High-resolution (1024(2) pixel) serial images were captured directly from the cryoplaned blockface using an integrated color digital camera and fiber optic illumination system mounted over a modified cryomacrotome. Specimens frozen and sectioned with the cranium intact preserved brain spatial relationships and anatomic bony landmarks. Color preservation was superior in unfixed tissue heads were incompatible with decalcification and cryoprotection procedures and section collection from such specimens was complicated by bone fragmentation. Collection of 1024(2) images from whole brain resulted in a spatial resolution of 200 microns/pixel in a 1-3 Gbyte data space. Even higher 3D spatial resolution was possible by primary image capture of selected regions such as hippocampus or brain stem. Discrete registration errors were corrected using image processing strategies such as cross-correlative and other algorithmic approaches. Data sets were amenable to resampling in multiple planes as well as scaling and transpositioning into standard coordinate systems. These methods enable quantitative measurements for comparison between subjects and to published atlas data. These techniques allow visualization and measurement at resolutions far higher than those available through other imaging technologies and provide greatly enhanced contrast for delineation of neuroanatomic structures, pathways, and subregions.

Brain↗
PubMed1994

Site of auditory plasticity in the brain stem (VLVp) of the owl revealed by early monaural occlusion.

1. The optic tectum of the barn owl contains a physiological map of interaural level difference (ILD) that underlies, in part, its map of auditory space. Monaural occlusion shifts the range of ILDs experienced by an animal and alters the correspondence of ILDs with source locations. Chronic monaural occlusion during development induces an adaptive shift in the tectal ILD map that compensates for the effects of the earplug. The data presented in this study indicate that one site of plasticity underlying this adaptive adjustment is in the posterior division of the ventral nucleus of the lateral lemniscus (VLVp), the first site of ILD comparison in the auditory pathway. 2. Single and multiple unit sites were recorded in the optic tecta and VLVps of ketamine-anesthetized owls. The owls were raised from 4 wk of age with one ear occluded with an earplug. Auditory testing, using digitally synthesized dichotic stimuli, was carried out 8-16 wk later with the earplug removed. The adaptive adjustment in ILD coding in each bird was quantified as the shift from normal ILD tuning measured in the optic tectum. Evidence of adaptive adjustment in the VLVp was based on statistical differences between the VLVp's ipsilateral and contralateral to the occluded ear in the sensitivity of units to excitatory-ear and inhibitory-ear stimulation. 3. The balance of excitatory to inhibitory influences on VLVp units was shifted in the adaptive direction in six out of eight owls. In three of these owls, adaptive differences in inhibition, but not in excitation, were found. For this group of owls, the patterns of response properties across the two VLVps can only be accounted for by plasticity in the VLVp. For the other three owls, the possibility that the difference between the two VLVps resulted from damage to one of the VLVps could not be eliminated, and for one of these, plasticity at a more peripheral site (in the cochlea or cochlear nucleus) could also explain the data. In the remaining two owls, there was no evidence of adaptive adjustment in the VLVp despite large adaptive adjustments in the optic tectum. 4. The adjustment of ILD coding in the VLVp was always substantially smaller than expected based on the adjustment of ILD tuning in the optic tectum measured in the same animals. This indicates the involvement of at least one additional site of adaptive plasticity in the auditory pathway above the level of the VLVp.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1998

Organization of retinal axons within the optic nerve, optic chiasm, and the innervation of multiple central nervous system targets Rana pipiens.

Light microscopic analysis of the optic nerve, chiasm, and optic tracts of Rana pipiens after the anterograde and retrograde transport of horseradish peroxidase has shown that retinal ganglion-cell axons reach the optic nerve head in chronotopically organized fascicles that form bands across the intraocular optic nerve. These bands of fascicles are divided along the midline in a "zone of reorganization" to create two full maps of the retinal surface; however, this map is discontinuous in that nasal and temporal quadrants are adjacent to one another. In the intracranial portion of the optic nerve, axons undergo another reorganization such that peripheral retinal axons shift position and become localized laterally and ventrally, whereas centrally placed axons become localized dorsally. Within this reorganization, the nerve is reconfigured into laminae of axons, and each lamina consists of age-related axons organized into two retinal maps. In the ipsilateral chiasm, axons diverge to form three central, optic tracts: the medial optic tract, the projection to the corpus geniculatum, and the basal optic root. Ipsilateral axons leave the chiasm at the same level of the chiasm as do their contralateral counterparts. The remaining axons converge in the lateral diencephalon to form a fourth fascicle, the marginal optic tract. Thus, within the optic chiasm, a sequence of positional transformations occur that result in the formation of multiple optic pathways. The various changes in axonal trajectory always coincide with changes in the orientation of cell groups that lie within the nerve and optic chiasm.

Animals↗
PubMed2006

From micro to nano: analysis of surface-enhanced resonance Raman spectroscopy active sites via multiscale correlations.

Effective correlation of data from a number of analytical techniques over length scales spanning several orders of magnitude is required to more fully investigate the active sites on silver nanoparticles that are responsible for surface-enhanced resonance Raman scattering (SERRS). In this paper, a method is presented that uses fluorescent beads as optical markers to allow direct correlation between a SERRS/fluorescence map and a transmission electron microscope (TEM) collage of the same area. Factors influencing the accuracy of the technique include the flatness of the substrate, the size of the fluorescent beads, and the strength of the signal from the fluorescent beads. When the effect of each of these factors on the technique is addressed, a simple and accurate correlation between the optical spectroscopy and the electron microscopy is achieved. A statistically significant number of particles can then be easily and reliably located and characterized at both optical limits, by SERRS, and with subnanometer resolution in the high-resolution TEM. Examples of HRTEM images and the locations of these particles within the SERRS map/TEM collage are presented. Our findings reveal that the relative SERRS activity of single particles is very low compared to dimers and larger aggregates of particles. The relative activity of dimers is estimated to be 12.4 times greater than single particles, and as the number of particles in the aggregate increase, the relative SERRS activity also increases. The relative SERRS activities of single particles/dimers/trimers/aggregates of 4-9 particles/aggregates of 10-20 are estimated to be 1/12.4/15.6/23.2/43.

Journal Article↗
PubMed2003

Simulated optical performance of custom wavefront soft contact lenses for keratoconus.

PURPOSE: Outstanding improvements in vision can theoretically be expected using contact lenses that correct monochromatic aberrations of the eye. Imperfections in such correction inherent to contact lenses are lens flexure, translation, rotation, and tear layer effects. The effects of pupil size and accommodation on ocular aberration may cause further difficulties. The purpose of this study was to evaluate whether nonaxisymmetric soft contact lenses could efficiently compensate for higher-order aberrations induced by keratoconus and to what extent rotation and translation of the lens would degrade this perfect correction. METHODS: Height topography data of nine moderate to severe keratoconus corneas were obtained using the Maastricht Shape Topographer. Three-dimensional ray tracing was applied to each elevation topography to calculate aberrations in the form of a phase error mapping. The effect of a nonaxisymmetric soft contact lens tailored to the corneal aberrations was simulated by adding an opposite phase error mapping that would theoretically compensate all corneal-induced optical aberrations of the keratoconus eyes. Translation (0.25, 0.5, 0.75, and 1.0 mm) and rotation (2.5 degrees, 5.0 degrees, 7.5 degrees, and 10 degrees ) mismatches were introduced. The modulation transfer function (MTF) of each eye with each displaced correction and with various pupil sizes (3, 5, and 7 mm) was deduced from the residual phase error mapping. A single performance criterion (mtfA) was calculated as the area under the MTF over a limited spatial frequency range (5 to 15 periods per degree). Finally, the ratio (RmtfA) of corrected mtfA over uncorrected mtfA provided an estimate of the global enhancement in contrast sensitivity with the customized lens. RESULTS: The contrast improvement ratios RmtfA with perfectly located lenses were for an average pupil size of 4.5 mm between 6.5 and 200. For small translation errors (0.25 mm), RmtfA ranged between 2 and 7. The largest lens translation tested (1 mm) often resulted in poorer performance than without correction (RmtfA <1). More than threefold improvements were achieved with any of the angular errors experimented. RmtfA values showed significant variations for pupil diameters between 3 and 7 mm. CONCLUSIONS: Three-dimensional aberration-customized soft contact lenses may drastically improve visual performance in patients with keratoconus. However, such lenses should be well positioned on the cornea. In particular, translation errors should not exceed 0.5 mm. Angular errors appeared to be less critical. It is further questioned whether the visual system is able to adapt to variations in optical performance of the correction in situ due to lens positioning and pupil size.

Contact Lenses, Hydrophilic↗
PubMed1993

Early monaural occlusion alters the neural map of interaural level differences in the inferior colliculus of the barn owl.

Monaural occlusion during early life causes adaptive changes in the tuning of units in the owl's optic tectum to interaural level differences (ILD) that tend to align the auditory with the visual map of space. We investigated whether these changes could be due to experience-dependent plasticity occurring in the auditory pathway prior to the optic tectum. Units were recorded in the external nucleus of the inferior colliculus (ICx), which is a major source of auditory input to the optic tectum. The tuning of ICx units to ILD was measured in normal barn owls and in barn owls raised with one ear occluded. ILD tuning at each recording site was measured with dichotic noise bursts, presented at a constant average binaural level, 20 dB above threshold. The best ILD at each site was defined as the midpoint of the range of ILD values which elicited more than 50% of the maximum response. A physiological map of ILD was found in the ICx of normal owls: best ILDs changed systematically from right-ear-greater to left-ear-greater as the electrode progressed from dorsal to ventral. Best ILDs ranged from 13 dB right-ear-greater to 15 dB left-ear-greater and progressed at an average rate of 12 dB/mm. The representations of ILD were similar on both sides of the brain. In the ICx of owls raised with one ear occluded, the map of ILD was shifted in the adaptive direction: ILD tuning was shifted towards values favoring the non-occluded ear (the direction that would restore a normal space map). The average magnitude of the shift was on the order of 8-10 dB in each of 4 owls. In one owl, the mean shift in ILD tuning was almost identical on both sides of the brain. In another owl, the mean shift was much larger on the side ipsilateral to the occlusion than on the contralateral side. In both cases, the mean shifts measured in each ICx were comparable to the mean shifts measured in the optic tectum on the same sides of the brain. Thus, the adjustments in ILD tuning that have been observed in the optic tectum in response to monaural occlusion are almost entirely due to adaptive mechanisms that operate at or before the level of the ICx.

Acoustic Stimulation↗
PubMed1999

Asymmetric connections, duplicate layers, and a vertically inverted map in the primary visual system.

The achiasmatic mutation is a remarkable and rare visual system mutation carried in a line of black sheepdogs. In affected animals, the optic chiasm is missing, and each retina projects entirely to the ipsilateral hemisphere. As a result of this navigational error, maps of visual space in the lateral geniculate nucleus (LGN) have a unique structure with mirror reversals of field position across the A-A1 border. Animals also have a persistent and severe congenital nystagmus. In this report we analyze a novel variant of the achiasmatic mutation, one in which retinal axons from only one eye successfully cross midline and in which the great majority of fibers from both eyes terminate in a single lateral geniculate nucleus. The dominant optic tract contains four times as many axons as the other tract. The hyperinnervated LGN has a lamination pattern consisting of duplicate and partly interwoven layers. A multiunit mapping study of visual cortex (primarily area 17 along the marginal gyrus) shows that receptive field topography and orientation selectivity are normal. The size of central binocular visual space is nearly normal and is flanked by monocular domains in the periphery. However, there is an inexplicable vertical inversion in the orientation of the cortical representation: superior fields are located rostrally, and inferior fields are located caudally. Despite a host of drastic abnormalities at all level of the visual system, from retina to cortex, this animal was behaviorally indistinguishable from normal dogs and did not have any detectable oculomotor abnormalities.

Animals↗
PubMed1987

Localization of the genes shaking-B, small optic lobes, sluggish-A, stoned and stress-sensitive-C to a well-defined region on the X-chromosome of Drosophila melanogaster.

Using deletion mapping and complementation tests, we have localized 5 behavioral mutations: shaking-B2, small optic lobesKS58, sluggish-AEE85, stonedts1, and stress-sensitive-C1 to 4 genetic complementation groups at the base of the X-chromosome. Shaking-B2 is an allele of the lethal complementation group R-9-29 near band 19E3; small optic lobesKS58 and sluggish-AEE85 belong to adjacent complementation groups, between lethals W2 and A112 near band 19F4; and stonedts1 and stress-sensitive-C1 are both alleles of the 8P1 lethal complementation group between lethals 114 and 13E3 near bands 20B-C.

Alleles↗