bluuebunny/crossref_metadata_2025_split huggingface dataset:
Representation of the ipsilateral visual field in the transition zone between areas 17 and 18 of the cat's cerebral cortex
Authors: Payne B. R. 
Published: June 2009

AbstractThe representation of the visual field in the architectonically defined transition zone between areas 17 and 18 of cat cerebral cortex was assessed by recording the activities and plotting the receptive fields of neurons at 2327 sites along 148 electrode penetrations made in 19 cats. The results show that the transition zone contains a significant representation of the ipsilateral visual hemifield although not all elevations in the visual field represented to the same extent. The shape of the field region represented resembles an hour glass, for the region represented is narrowest on the 0-deg horizontal meridian and increasingly wider at progressively more positive and negative elevations. When receptive-field centers are considered, the extent of the representation reaches to -2.5 deg on the 0-deg horizontal meridian and to 10 or more degrees towards the field periphery. When receptive-field areas are considered, the representation at the 0-deg horizontal meridian extends to -3.6 deg and to beyond 20 deg at other elevations. In contrast, the visual-field representations in flanking areas 17 and 18 are essentially limited to the contralateral hemifield. The presence of a distinct representation of part of the ipsilateral hemifield in the transition zone suggests that the zone may have connections distinctly different from those of the adjacent areas. The observations bear on the problems of understanding the visual pathways in hypopigmented cats and binocular disparity mechanisms about the midline.
Receptive fields of neurons at the confluence of cerebral cortical areas 17, 18, 20 a, and 20 b in the cat
Authors: Payne B. R. , Siwek D.F. 
Published: June 2009

AbstractThe activity of neurons was recorded extracellurayly at the junction of visual cortical areas 17, 18, 20a, and 20b in the cat. The receptive fields of these neurons were striking for their size, which ranged from a diameter of more than 40 deg of visual angle to the complete visual of the contralateral eye. It is speculated that these large receptive fields may be generated by perturbations in the individual maps as the four areas merge together.
Recovery from bleaching in photoreceptors promoted by biotin, pyruvate, and glucose
Authors: Leibovic K.N. , Bandarchi J. 
Published: June 2009

AbstractIn the rods ofBufo marinusand other species, bleaching of the rhodopsin in isolated cells leads to a loss of sensitivity and response amplitude and to a shortened response duration. These changes are permanent for cells bathed in Ringer&amp;s solution. They are due to as yet unknown modulations in the transduction biochemistry. In this paper, we report that these changes can be partly or completely reversed by supplying biotin, pyruvate, and elevated glucose to the rod. The time course of this reversal and the substances which promote it imply that these are metabolically mediated effects. Based on the reported action of biotin and pyruvate on the one hand and on the changes of the response waveforms on the other hand, we believe that the phenomena we observe involve the later steps of the transduction cycle.
Centrifugal pathways to the retina: which way does the “searchlight” point?
Authors: Holden A. L. 
Published: June 2009

AbstractThis commentary extends the review by Hiroyuki Uchiyama (1989) entitled “Centrifugal pathways to the retina: influence of the optic tectum”Visual Neuroscience3, 183–206. A further scrutiny is made of the topography of the isthmo-retinal projection of the pigeon, which provides the most fully investigated example of a retinopetal projection. It is suggested that the topographical organization in this system is compatible with it's input being derived from the lower visual field (and upper retina) and it's output being directed to the horizon and lower retina. This is another form of attentional hypothesis for the centrifugal pathway, compatible with a role in ground feeding, and is testable by current tracing techniques in neurobiology.
Photoreceptor cells dissociated from the compound lateral eye of the horseshoe crab,Limulus polyphemus, II: Function
Authors: Hanna W. J. Brad , Johnson Edwin C. , Chaves Deborah , Renninger George H. 
Published: June 2009

AbstractA combination of enzymatic digestions and mechanical disruption was used to isolate photoreceptor cells from the compound lateral eye of the horseshoe crab,Limulus polyphemus. The cells were maintained in a culture medium and tested for function using whole-cell and cell-attached patch configurations of the gigaseal technique. The cells dissociated from the eye generated spontaneous voltage and current bumps in the dark, and depolarized in a graded fashion to increasing intensities of light over several decades, producing responses similar to those of cellsin vivo. Currents evoked during voltage clamp were similar to those in ventral photoreceptor cells ofLimulus, although transient currents in the dark- and light-activated currents were smaller in isolated lateral eye cells, perhaps because of the slow speed and spatial nonuniformity of the clamp in these large cells. In addition to isolated cells, dissociation of the compound eye produced small clusters of cells and isolated ommatidia which were also tested for function. Comparison of the electrical characteristics of isolated cells with those of cells in small clusters and in their ommatidial matrix suggests that the electrical junctions normally connecting photoreceptor cells within an ommatidium are functional in the latter groups, but not in isolated cells. Cell-attached patches of rhabdomeral membrane of isolated cells contained light-activated channels, resembling those observed in ventral photoreceptor cells, but no voltage-activated channels. Similar patches of arhabdomeral membrane contained voltage-activated channels, but no light-activated channels. We conclude that this preparation is suitable for studies of processes involved in generating the light response in invertebrate photoreceptor cells.
Regulation of melatonin and dopamine biosynthesis in chick retina: The role of GABA
Authors: Kazula Arkadiusz , Nowak Jerzy Z. , Iuvone P. Michael 
Published: June 2009

AbstractMelatonin biosynthesis in chick retina occurs as a circadian rhythm. Biosynthesis of the neurohormone is highest at night in darkness, and is suppressed by light. The role of gamma-aminobutyric acid (GABA) in the nocturnal regulation of melatonin synthesis was examined. Systemic or intravitreal administration of muscimol, a GABA-A receptor agonist, to light-exposed chicks at the beginning of the dark phase of the light/dark cycle increased retinal melatonin levels and the activity of serotonin N-acetyltransferase (NAT), a key regulatory enzyme of the melatonin biosynthetic pathway. Baclofen, a GABA-B receptor agonist, also increased NAT activity of light-exposed retinas, but muscimol was approximately 40-fold more potent than baclofen. Effects of both muscimol and baclofen on NAT activity were inhibited by GABA-A antagonists, bicuculline and picrotoxin, and the effect of baclofen was unaffected by the GABA-B selective antagonist, CGP 35348. Thus, activation of GABA-A receptors appears to be associated with increased melatonin biosynthesis. The GABA-uptake inhibitor, nipecotic acid, and the GABA-transaminase inhibitor, aminooxyacetic acid, also increased NAT activity of light-exposed retinas. The high levels of NAT activity associated with exposure to darkness were unaffected by either muscimol or baclofen, but picrotoxin and bicuculline significantly inhibited retinal NAT activity in darkness.The rate of dopamine synthesis, estimated fromin situtyrosine hydroxylase activity, was higher in light-exposed retinas than in darkness. Muscimol inhibited dopamine synthesis in light, and picrotoxin stimulated dopamine synthesis in darkness. The stimulation of melatonin synthesis by muscimol in light-exposed retinas appears to be related to inhibition of retinal dopamine neurons. The increase of NAT activity elicited by muscimol in light-exposed retinas was inhibited by administration of the dopamine receptor agonists apomorphine and quinpirole. Blocking dopamine receptors with spiperone or inhibiting dopamine biosynthesis with α-methyl-ρ tyrosine also increased NAT activity in light, and the effects of the dopamine antagonists and muscimol were not additive. The decrease of NAT activity elicited by GABA antagonists in darkness was inhibited by spiperone. Thus, GABA may indirectly regulate retinal melatonin biosynthesis, by inhibiting dopaminergic activity in retina.
Appetitive responses to computer-generated visual stimuli by the praying mantisSphodromantis lineola(Burr.)
Authors: Prete Frederick R. , Mahaffey Robert J. 
Published: June 2009

AbstractTethered adult female praying mantises,Sphodromantis lineola(Burr.), were presented with various computer-generated visual stimuli that moved against patterned or homogeneous white backgrounds in predetermined patterns and at predetermined speeds. The degrees to which the stimulus configurations elicited appetitive behaviors (attempting to approach and/or striking) indicated the relative degrees to which the stimuli were classified as prey. Mantises readily struck at cartoon “crickets” that subtended visual angles as great as 24.5 deg x 62.5 deg, but response rate was suppressed if the stimuli were superimposed on horizontally moving patterned backgrounds. Mantises also displayed appetitive behaviors to moving black squares (edge lengths = 10–47 deg) that moved in predetermined “erratic” paths; however, their response rates were affected by several factors: (1) response rate declined as edge length increased over 10 deg; (2) striking was emitted to stimuli viewed from 23 mm (but not farther) away; and (3) both stimulus displacement rate (distance moved between video frames) and apparent speed (video frame rate) dramatically affected the releasing strength of the stimuli. Finally, mantises responded appetitively to random dot patterns moving synchronously against identically patterned backgrounds and to pairs of black squares moving synchronously against a white background. However, in the latter case, response rate declined as the squares were moved farther apart horizontally or vertically. These and previous results from our laboratory on mantises are congruent with behavioral results obtained from other insects such as flies (Diptera) and dragon flies (Odonata) and suggest that there are neuroanatomical similarities between these groups.
Glycine in the lizard retina: Comparison to the GABA system
Authors: Sherry David M. , Micich Alex , Yazulla Stephen 
Published: June 2009

AbstractNeurons likely to utilize glycine (GLY) as a neurotransmitter were identified immunocytochemically in the “all-cone” lizard retina and the basic anatomical organization of the retinal GLY and gamma-aminobutyric acid (GABA) systems was compared. Four types of GLY-immunoreactive (GLY-IR) neurons were identified. Most GLY-IR cells were amacrine cells, which comprised at least two types. GLY-IR interplexiform cells and ganglion cells also were identified. The first GLY-IR amacrine cell type was characterized by a small pyriform soma, located distal to the border of the inner plexiform layer (IPL), and fine dendrites. Most GLY-IR amacrine cells were of this type and several subtypes may exist within this group. The second amacrine cell type was characterized by a large, distally located soma and a large descending process. This amacrine cell type showed colocalization of GLY-IR and GABA-IR and comprised about 4% of the total GLY-IR amacrine cell population.Comparison of GLY-IR and GABA-IR on serial sections showed that GLY and GABA were present in largely separate neuronal populations. Generally, GLY-IR amacrine cells were smaller, more distally located in the inner nuclear layer and had finer dendrites than GABA-IR amacrine cells. Distribution of GLY-IR and GABA-IR in the outer plexiform layer and the inner plexiform layer differed considerably.Based on the segregated distribution of GLY-IR and GABA-IR in the synaptic layers of the lizard retina, GLY and GABA may have fundamentally different roles in retinal processing.
Visual pigments in the sea lamprey, Petromyzon marinus
Authors: Hárosi Ferenc I. , Kleinschmidt Jochen 
Published: June 2009

AbstractWe present microspectrophotometric evidence for the existence of two distinct visual pigments residing in two different morphological types of photoreceptor of the sea lamprey. In the upstream migrant Petromyzon marinus, the pigment found in short receptors has a wavelength of peak absorbance (λmax) of 525 nm, whereas the pigment located in long receptors has a λmax of 600 nm. Although the former appears to be pure porphyropsin, the latter is akin to visual pigments found in the red-absorbing cones of amphibian and teleost retinae. The kinship is more than superficial pertaining to λmax of the a–band absorbance to its native maximum value. The presence of an anion-sensitive and an anion-insensitive pigment in a retina implies the expression of two distinct opsin genes. We infer this from several examples of correlation between anion sensitivity and opsin sequence groupings. Moreover, the presence of two distinct opsin genes expressed throughout six vertebrate classes implies their existence in a common ancestor to all.
The effects of V4 and middle temporal (MT) area lesions on visual performance in the rhesus monkey
Authors: Schiller Peter H. 
Published: June 2009

AbstractThe effects of V4, MT, and combined V4+MT lesions were assessed on a broad range of visual capacities that included measures of contrast sensitivity, wavelength and brightness discrimination, form vision, pattern vision, motion and flicker perception, stereopsis, and the selection of stimuli that were less prominent than those with which they appeared in stimulus arrays. The major deficit observed was a loss in the ability, after V4 lesions, to select such less prominent stimuli; this was the case irrespective of the manner in which the stimulus arrays were made visible, using either luminance, chrominance, motion, or stereoscopic depth as surface media. In addition, V4 lesions yielded mild deficits in color, brightness, and form vision whereas MT lesions yielded mild to moderate deficits in motion and flicker perception. Both lesions produced mild deficits in contrast sensitivity, shape-from-motion perception, and yielded increased reaction times on many of the tasks. The impairment resulting from combined V4 and MT lesions was not greater than the sum of the deficits of either lesion. None of the lesions produced significant deficits in stereopsis. The findings suggest that (1) area V4 is part of a neural system that is involved in extracting stimuli from the visual scene that elicit less neural activity early in the visual system than do other stimuli with which they appear and (2) several other extrastriate regions and more than just two major cortical processing streams contribute to the processing of basic visual functions in the extrastriate cortex.
Spatial receptive-field structure of cat retinal W cells
Authors: Rowe Michael H. , Cox James F. 
Published: June 2009

AbstractWe have used frequency-domain methods to characterize the spatial receptive-field structure of cat retinal W cells. For most ON- and OFF-center tonic and phasic W cells, measurements of responsivity to drifting gratings at various spatial frequencies could be adequately described by a difference-of-Gaussians (DOG) function, consistent with the presence of center and surround mechanisms that are approximately Gaussian in shape and whose signals are combined additively. Estimates of the responsivity of the center mechanisms of tonic and phasic W cells were similar, but both were significantly lower than the corresponding values for X or Y cells. The width of the center mechanisms of tonic W cells, phasic W cells, and Y cells did not differ significantly from each other, but all were significantly larger than the width of X-cell centers. Surround parameters did not vary significantly among the four groups of ganglion cells. Measurements of contrast gain in both tonic and phasic W cells gave values that were significantly lower than in X or Y cells.Virtually all of the phasic W cells in our sample displayed evidence of spatial non-linearities in their receptive fields, in the form of either d.c. responses to drifting sine-wave gratings or second harmonic responses to counterphased gratings. The spatial resolution of the mechanism underlying these nonlinearities was typically higher than that of the center mechanism of these cells. Most tonic W cells exhibited linear spatial summation, although a subset gave strong second harmonic responses to counterphased gratings.Spatial-responsivity measurements for most ON-OFF and directionally selective W cells were not adequately described by DOG functions. These cells did, however, show evidence of spatial nonlinearities similar to those seen in phasic W cells. Suppressed-by-contrast cells gave both modulated and unmodulated responses to drifting gratings which both appeared to involved rectification, but which differed from each other in both spatial resolution and contrast gain.These data confirm earlier reports that the receptive fields of tonic and most ON- or OFF-center phasic W cells appear to include classical center and surround mechanisms. However, the receptive fields of some phasic cells, as well as ON-OFF and directionally selective W cells may have quite different structures. Our results also suggest that phasic, ON-OFF, directionally selective, suppressed-by-contrast, and a subset of tonic W cells may all receive nonlinear inputs with characteristics similar to those described in the receptive fields of retinal Y cells. If so, this has important implications for identifying and understanding the presynaptic circuitry of W cells, as well as the nature of their output to both telencephalic and midbrain visual targets.
Immunocytochemical evidence for the presence of histamine and GABA in photoreceptors of the barnacle (Balanus nubilus)
Authors: Callaway Joseph C. , Stuart Ann E. , Edwards John S. 
Published: June 2009

AbstractBiochemical evidence indicates that GABA and histamine may both be synthesized by barnacle photoreceptors (Koike & Tsuda, 1980; Timpe & Stuart, 1984; Callaway & Stuart, 1989b). We used antisera against GABA- and histamine-protein conjugates to determine whether the photoreceptors contain either or both of these antigens. Both antisera labeled all of the photoreceptors in each of the three ocelli. Histamine-like immunoreactivity was found throughout each photoreceptor cell but was most intense at their presynaptic terminals. Histamine-like immunoreactivity was blocked by preincubation of the antibody either with histamine or with a histamine-protein conjugate. GABA-like immunoreactivity was found in all parts of the photoreceptors including the cell body, axon, rhabdomeric dendrites, and presynaptic terminals. GABA-protein conjugates blocked the GABA-like labeling of the photoreceptors, while protein conjugates with histamine, L-glutamate, L-glutamine, β-alanine, and taurine did not. Histamine-like immunoreactivity in the supraesophageal ganglion was confined to the photoreceptor terminals and a second, loose plexus of endings in the main neuropil. GABA-like immunoreactivity, in contrast, was found in approximately twenty-five pairs of neurons of this ganglion. In the cirral nerves, which are expected to contain inhibitory motoneurons, unidentified axons also labeled with the GABA antiserum.
Biochemical and physiological evidence that histamine is the transmitter of barnacle photoreceptors
Authors: Callaway Joseph C. , Stuart Ann E. 
Published: June 2009

AbstractWe tested the hypothesis that histamine is the transmitter released by barnacle photoreceptors. Median and lateral ocelli were incubated with3H-histidine and found to synthesize3H-histamine, identified by high-voltage electrophoresis. Synthesis could be blocked by the histidine decarboxylase inhibitor (S)-α-fluoromethylhistidine. Histamine was applied to 1-cells either by superfusion or by pressure ejection from a pipette (100 µM or 1 mM histamine) positioned close to the I-cell's soma. When bath-applied at concentrations ranging from 5–100 µM, histamine hyperpolarized the I-cell in a dose-dependent fashion and increased its conductance. At 100 µM, histamine abolished the I-cell's response to light. The response to a pulse of pressure-applied histamine was a hyperpolarization whose amplitude was graded with dose (determined by the duration of the pulse). This response persisted in concentrations of Co2+and Cd2+that blocked synaptic transmission from the photoreceptors. Cimetidine, an antagonist of mammalian H2 receptors, markedly decreased the cell's responses both to HA and to light at 100 µM and blocked both responses at 1 mM. Pyrilamine and triprolidine, H1 antagonists, had a complex effect on the I-cell's responses to histamine and to light. Neither H1 nor H2 antagonists, nor histamine itself, affected the voltage or light responses recorded in the presynaptic terminal region, or any phase of calcium-dependent action potentials induced in the terminal in the presence of tetraethylammonium ion. Thus, biochemical, immunocytochemical, and physiological evidence suggests that HA is the transmitter from these photoreceptors to the I-cells. Although gammaaminobutyric acid (GABA) is also present in the photoreceptors, it did not affect the I-cell's responses to light or to histamine when bath-applied at 100 µM. Thus, GABA does not appear to modulate transmission from the photoreceptor to the I-cell.
Harmonic basis functions for spatial coding in the cat striate cortex
Authors: Glezer V. D. , Yakovlev V. V. , Gauzelman V. E. 
Published: June 2009

AbstractThe number of subregions in the activity profiles of simple cells varies in different cells from 2–8; that is, the number of cycles in the weighting function varies from 1–4. The distribution of receptive-field (RF) sizes at eccentricities of 0-6 deg are clustered at half-octave intervals and form a discrete distribution with maxima at 0.62, 0.9, 1.24, 1.8, 2.48, and 3.4 deg. The spatial frequencies to which the cells are tuned are also clustered at half-octave intervals, forming a discrete distribution peaking at 0.45, 0.69, 0.9, 1.35, 1.88, 2.7, 3.8, and 5.6 cycles/deg. If we divide the RF sizes by the size of the period of the subregions, then the average indices of complexity (really existing) or the number of cycles in the weighting function form (after normalization) the sequences: 1, 1.41, 2.0, 2.9, 4.15.The relation between the bandwidth of the spatial-frequency characteristic and the optimal spatial frequency is in accordance with predictions of the Fourier hypothesis. The absolute bandwidth does not change with the number of cycles/module. This means that inside the module the absolute bandwidth does not change with the number of the harmonic. The results allow us to suggest the following. A module of the striate cortex, which is a group of cells with RFs of equal size projected onto the same area of central visual field, accounts for the Fourier description of the image. The basis functions of the module are composed of four harmonics only, irrespective of size and position of the module.Besides linear cells (sinusoidal and cosinusoidal elements), the module contains nonlinear cells, performing a nonlinear summation of the responses of sinusoidal and cosinusoidal elements. Such cells are characterized by an index of complexity which is more than the number of cycles in the weighting function and by marked overlap of ON and OFF zones. The analysis of organization suggests that the cells can measure the amplitude and phase of the stimulus.