Showing papers on "Orientation column published in 1984"

Form, function and intracortical projections of spiny neurones in the striate visual cortex of the cat.

Abstract: We have studied the neuronal circuitry and structure-function relationships of single neurones in the striate visual cortex of the cat using a combination of electrophysiological and anatomical techniques. Glass micropipettes filled with horseradish peroxidase were used to record extracellularly from single neurones. After studying the receptive field properties, the afferent inputs of the neurones were studied by determining their latency of response to electrical stimulation at different positions along the optic pathway. Some cells were thus classified as receiving a mono- or polysynaptic input from afferents of the lateral geniculate nucleus (l.g.n.), via X- or Y-like retinal ganglion cells. Two striking correlations were found between dendritic morphology and receptive field type. All spiny stellate cells, and all star pyramidal cells in layer 4A, had receptive fields with spatially separate on and off subfields (S-type receptive fields). All the identified afferent input to these, the major cell types in layer 4, was monosynaptic from X- or Y-like afferents. Neurones receiving monosynaptic X- or Y-like input were not strictly segregated in layer 4 and the lower portion of layer 3. Nevertheless the X- and Y-like l.g.n. fibres did not converge on any of the single neurones so far studied. Monosynaptic input from the l.g.n. afferents was not restricted to cells lying within layers 4 and 6, the main termination zones of the l.g.n. afferents, but was also received by cells lying in layers 3 and 5. The projection pattern of cells receiving monosynaptic input differed widely, depending on the laminar location of the cell soma. This suggests the presence of a number of divergent paths within the striate cortex. Cells receiving indirect input from the l.g.n. afferents were located mainly within layers 2, 3 and 5. Most pyramidal cells in layer 3 had axons projecting out of the striate cortex, while many axons of the layer 5 pyramids did not. The layer 5 cells showed the most morphological variation of any layer, were the most difficult to activate by electrical stimulation, and contained some cells which responded with the longest latencies of any cells in the striate cortex. This suggests that they were several synapses distant from the l.g.n. input. The majority of cells in layers 2, 3, 4 and 6 had the same basic S-type receptive field structure. Only layer 5 contained a majority of cells with spatially overlapping on and off subfields (C- and B-type receptive fields).(ABSTRACT TRUNCATED AT 400 WORDS)

Cortical projections to the superior colliculus in the macaque monkey: A retrograde study using horseradish peroxidase

Abstract: The topical and laminar distribution of corticotectal cells, as well as their size and morphology, were studied in the macaque monkey with the horseradish peroxidase (HRP) technique. After HRP injections restricted primarily to the superficial layers of the colliculus, labelled cells were found in visual cortex (areas 17, 18, and 19) and both in the frontal eye field (area 8) and the adjacent part of premotor cortex (area 6). The clustering of labelled cells in visual cortex indicated that each of the anatomically and functionally distinct visual areas has its own set of collicular projections. When intermediate and deeper layers of the colliculus were injected, labelled cells were found also in posterior parietal cortex (area 7) where they were concentrated mainly on the posterior bank of the intraparietal fissure, in inferotemporal cortex (areas 20 and 21), in auditory cortex (area 22), in the somatosensory representation SII (anterior bank of sylvian fissure, area 2), in upper insular cortex (area 14), in motor cortex (area 4), in premotor cortex (area 6), and in prefrontal cortex (area 9). In the motor and premotor cortex, labelled cells formed a continuous band which appeared to stretch across finger-hand-arm-shoulder-neck representation. Similarly, the cluster of labelled cells in area 2 may correspond to the finger-hand representation of SII. The cortical regions not containing labelled cells were the somatosensory representation SI (areas 3, 1 and 2) and the infraorbital cortex. Labelled cells were restricted to layer V of all cortical areas except in the primary visual cortex, where labelled cells were found in both layer V and layer VI. The size spectrum of corticotectal cells ranged from 14.8 micron (average diameter) in area 17 to 27.8 micron in area 6, comprising cells as small as 8 micron and as large as 45 micron. Labelled cells in posterior parietal (area 7), in auditory (area 22), and in motor cortex (area 4) were small and distributed over only a narrow range of sizes. Those in premotor cortex (area 6) were often large and had a wide range in size distribution. The differences in size and morphology of corticotectal neurons suggest that they do not form a uniform class of neurons.

Physiological organization of layer 4 in macaque striate cortex

Abstract: Numerous highly angled electrode penetrations through the opercular region of macaque striate cortex reveal that layers 4A, 4C alpha, and 4C beta--the primary input sublaminae for axons from the lateral geniculate nucleus (LGN)--are retinotopically organized on a fine scale and populated mostly by monocularly driven cells having small receptive fields and lacking orientation selectivity. Layer 4B, which does not receive a direct thalamic input, contains orientationally selective cells, and many of these are also direction selective. To a significant degree the response properties of cells in layers 4C alpha and 4C beta reflect the response properties of their respective afferent inputs, from the magno- and parvocellular laminae of the LGN. Accordingly, cells in layer 4C alpha have lower contrast thresholds and larger minimum response fields than do the cells in layer 4C beta. In contrast to this clear-cut separation, the cells of layer 4A (whose major source of direct LGN input arises from the parvocellular layers) exhibit both high and low contrast thresholds. With regard to the precision of retinotopic mapping that is seen in lamina 4C, it is noteworthy that there is substantial overlap among the minimum response fields of neighboring neurons. Due to a larger mean receptive field size, this overlap is greater in layer 4C alpha than it is in 4C beta. In either sublamina, however, the minimum cortical distance that separates different and nonoverlapping parts of the visual field corresponds closely--within a factor of 2--to the known arborizational spreads of single geniculate afferents.

Patterns of synaptic input to layer 4 of cat striate cortex

Abstract: Although cells in layer 4 of cat striate cortex represent the first stage in the cortical processing of visual information, they have considerably more complicated receptive field properties than the afferents to the layer from the lateral geniculate nucleus. In considering how these properties are generated, we have focused on the intrinsic cortical circuitry, and particularly on the projection to layer 4 from layer 6. Layer 6 pyramidal cells were injected with horseradish peroxidase and examined at the light and electron microscopic level. The labeled axon terminals were found to form asymmetric synapses and to show a strong preference for contacting dendritic shafts. Serial reconstruction of dendrites postsynaptic to labeled layer 6 cell axon terminals showed that a large proportion of the postsynaptic dendrites belonged to smooth and sparsely spiny stellate cells, suggesting a selective innervation of these cell types. In contrast, the geniculate projection to layer 4 made synapses primarily with dendritic spines and, as a result, the large majority of terminals ended on spiny cells. Since smooth and sparsely spiny stellate cells are thought to mediate inhibition within the cortex, we suggest that one effect of the layer 6 to layer 4 projection could be to contribute to inhibitory features of the receptive fields of layer 4 cells.

Relation of callosal and striate-extrastriate cortical connections in the rat: Morphological definition of extrastriate visual areas

Abstract: The main purpose of this study was to correlate the tangential distributions of visual callosal and striate-extrastriate connections in the rat. Cells of origin and terminations of the visual callosal pathway of one hemisphere were labeled by the anterograde and retrograde transport of horseradish peroxidase (HRP) after multiple injections of this enzyme in the contralateral hemisphere, while ipsilateral striate-extrastriate projection fields were revealed by using the autoradiographic method following single injections of 3H-proline in striate cortex. A remarkable complementarity in the distribution of both cortico-cortical pathways was revealed by superimposing in a camera lucida the patterns of callosal and striate-extrastriate projections from consecutive tangential sections processed for HRP and autoradiography, respectively. Projections from striate cortex are distributed into multiple extrastriate fields which are partially or totally surrounded by cortical strips containing dense and overlapping accumulations of labeled callosal cells and terminations. In addition to projections to the following striate recipient areas described in previous reports: posterior (P), posterolateral (PL), lateromedial (LM), laterolateral (LL), anterolateral (AL) and anteromedial (AM); projections to laterointermediate (LI), laterolateral anterior (LLa), anterior (A), medial (M) and pararhinal (PR) areas were defined in the present study. Striate-extrastriate projection fields occupy only a portion of the acallosal islands that contain them, and the location of the fields within these islands correlates with the retinotopic location of the isotope injection in striate cortex. When compared to previous physiological and anatomical maps of extrastriate visual areas in the rat, the present results indicate that the distribution of callosal connections correlates with the borders of extrastriate visual areas, and that the projection from striate cortex into these areas is retinotopically organized. Surprisingly, a direct projection from striate cortex to the head representation region in somatosensory cortex was labeled, a finding that challenges the view that primary sensory areas do not connect directly.

Corticocortical connections to the motor cortex from the posterior parietal lobe (areas 5a, 5b, 7) in the cat demonstrated by the retrograde axonal transport of horseradish peroxidase.

Abstract: Neurons in the parietal region of the cerebral cortex, projecting to the ipsilateral distal forelimb area of the motor cortex (area 4γ) were identified in the cat brain using the horseradish peroxidase (HRP) retrograde tracing method. After making microinjections of HRP into the distal forelimb area of the motor cortex, clusters of HRP-labeled cell bodies were observed in different regions of the ipsilateral parietal cortex. In particular these clusters of labeled cells were found in areas 5a, 5b and 7. The area 5a cluster is formed from closely packed irregularly-shaped cells, the area 5b cluster is made up of dispersed medium-sized pyramidal cells, while area 7 contains a cluster of widely dispersed small pyramidal cells. Typically, labeled cell bodies were found in lamina III of cortex. Labeled cell bodies were neither observed in the contralateral cortex nor in the visual cortex (areas 17, 18 and 19). Since parietal cortex receives projections from primary somatosensory and visual cortex, the projections from parietal to motor cortex may well form the neural substrate for the processing of convergent sensory information used in voluntary movements.

Cortical connections of the anteromedial extrastriate visual cortex in the rat.

Abstract: Efferent and afferent connections of the visually responsive cortex (area anteromedial, AM) located in the anterior portion of area 18b were studied with degeneration and horseradish peroxidase (HRP) methods following small lesions and HRP injections into this area Degenerating axons, terminals and retrogradely HRP-labeled neurons were observed in a broad region of the cortex including areas located lateral, medial and anterior to the striate cortex The main finding of this study is that connections of area AM with area 18a are distributed in discrete patches whose arrangement is similar to that of the lateral extrastriate visual areas postulated in previous physiological and anatomical reports These results thus suggest that visual area AM is reciprocally connected with visual areas in area 18a Area AM is also connected with other regions within area 18b, thus supporting the notion advanced by recent studies that area 18b contains more than one visual area A weak afferent connection to area AM from the dorsal lateral geniculate nucleus of the thalamus was noted Previously described connections of area 18b with areas 8 and 29 as well as with the lateral and latero-posterior thalamic nuclei were confirmed in the present study

Processing of Visual Information within the Retinostriate System

Abstract: The sections in this article are: 1 Retinostriate Pathway 2 Retina 2.1 Cat Retina 2.2 Monkey Retina 3 Visual Thalamus 3.1 Cat Dorsal Lateral Geniculate Nucleus (LGN) 3.2 Medial Interlaminar Nucleus 3.3 Perigeniculate Nucleus and Nucleus Reticularis Thalami 3.4 Extrageniculate Visual Thalamus 3.5 Macaque Lateral Geniculate Nucleus 3.6 Macaque Pregeniculate Nucleus 3.7 Extrageniculate Visual Thalamus in Monkey 4 Visual Cortex 4.1 Cat Striate Cortex (Area 17) 4.2 Monkey Striate Cortex 5 Binocular Vision 6 Conclusion

Retinotopy and orientation columns in the monkey: A new model

Abstract: A model is presented in which orientation columns arise directly out of retinotopy. According to the model, iso-orientation lines are arrayed radially around nodal centers which correspond to cytochrome oxidase patches. The nodal centers form a square matrix superimposed upon the map of ocular dominance stripes. In the supragranular layers horizontal iso-orientation lines run down the centers of ocular dominance stripes, with vertical iso-orientation lines crossing perpendicularly. Diagonal orientations (45° and 135°) are represented as alternating iso-orientation zones at the centers of the interstices in the matrix (internodal centers). Preferred orientations in the infragranular layers are reversed with respect to the supragranular layers. The model is consistent with new data concerning ocularity and preferred orientation in systematic penetrations through striate cortex, and helps to explain some previously puzzling features of the relationship between ocular dominance columns, orientation columns and retinotopy.

Relationship between preferred orientation and receptive field position of neurons in extrastriate cortex (area 19) in the cat.

Abstract: Orientation sensitivity is a characteristic of most retinal ganglion cells (Levick and Thibos, '82), most relay cells in the dorsal lateral geniculate nucleus (Vidyasagar and Urbas, '82), and most neurons in the visual cortex (Hubel and Wiesel, '62) in the cat. In the retina there is a systematic relationship between receptive field position (polar angle) and preferred orientation. Outside of the area centralis most retinal ganglion cells respond best to stimuli oriented radially, i.e., oriented parallel to the line connecting their receptive fields to the area centralis (Levick and Thibos, '82). This relationship is strongest along the horizontal meridian (the visual streak) and appears to reflect the innate, radial orientation of retinal ganglion cell dendritic fields (Leventhal and Schall, '83). A relationship between preferred orientation and polar angle also exists in cat striate cortex; outside of the area centralis representation most cells respond best to lines oriented radially. This relationship is strongest for S type cells, the most orientation-selective cells, and cells in regions representing the horizontal meridian (Leventhal, '83). To determine if similar relationships exist in cat extrastriate cortex, the preferred orientations and receptive field positions of 226 neurons in area 19 were studied. We find that, as in area 17, most area 19 cells outside of the representation of the area centralis respond best to lines oriented radially; this relationship is strongest for the cells having the narrowest receptive fields and in regions subserving the horizontal meridian. Unlike in striate cortex, in area 19 the relationship between preferred orientation and polar angle is not dependent upon cell type (S or C) or to the degree of orientation sensitivity exhibited. Also, in area 19, but not in area 17, the relationship between preferred orientation and polar angle fails for the cells having the widest receptive fields. The results of this study show that the systematic relationship between preferred orientation and receptive field position which begins in the retina is largely preserved through extrastriate cortex. The functional architecture of orientation sensitive cells throughout the visual pathways may depend ultimately upon the innate, radial orientation of the dendritic fields of retinal ganglion cells.

Numbers of specific types of neuron in layer IVab of cat striate cortex

Abstract: Layer IVab of the visual cortex (area 17) of the cat contains about 51,400 neurons per mm3, including about 400-1200 per mm3 of each of three categories of neuron believed from previous work to represent discrete types. Each type forms about 0.5-1.5% of all the IVab neurons, which suggests that the total number of types in this layer might be much greater than previously supposed, perhaps as many as 50 or more. From their densities and estimates of their dendritic fields, we calculate that each type completely "covers" layer IVab in the tangential plane but only by a small factor (1.3-4.2).

An attempt to explain the differences between the upper and lower halves of the striate cortical map of the cat's field of view

Abstract: Cowey and Rolls have shown that the magnification factor with which the retina is imaged onto the striate cortex is proportional to visual acuity. Schwartz has used this to derive how visual peripheral acuity in the human varies with distance from the fovea, in good agreement with experiment. The same reasoning applied to the map of the lower half of the field of view as imaged onto the striate cortex of the cat indicates that the cat fixating a point up to about 100 cm in front of him sees the foreground portion of the horizontal surface on which he is standing approximately uniformly blurred.

Seeing with the visual cortex

Abstract: A short analysis of the input-output organization of the primary visual cortical areas in the cat and monkey is followed by a description of the salient microelectrophysiological properties of retino-geniculo-cortical system neurons. It is concluded that a strict hierarchical model of cortical processing of visual information is no longer tenable.

Comparison of topographic and spatial-frequency characteristics of the lateral suprasylvian and striate cortex in cats

Abstract: Differences in spatial frequency and topographic characteristics of receptive fields of neurons in two visual projection areas (striate cortex and lateral suprasylvian region) were analyzed on the basis of results of the writer's previous and present investigations. Receptive fields of neurons in the suprasylvian cortex are large; their size increases with eccentricity and the transmission band occupies a region of low and intermediate spatial frequencies. Receptive fields of striate cortical neurons, on the other hand, are small; they increase in size with eccentricity and the transmission band lies in the region of intermediate and high spatial frequencies. The latent period of evoked potentials is longer in the striate than in the suprasylvian cortex. Analysis of spatial low-frequency information is processed in the suprasylvian cortex a little earlier than high-frequency information is processed in the striate cortex. Retinotopically organized interaction of projection zones enables the two descriptions of a perceived scene to be correlated.

Visually Evoked Responses from Non-Occipital Areas of the Human Cortex.

Abstract: : Visually evoked neuromagnetic responses from the central area of the cerebral cortex in addition to the usual responses from the occipital areas of primary visual cortex are observed when the velocity of a moving grating pattern was modulated sinusoidally. The source of the central field has different functional properties than the source in primary sensory cortex. The position, depth, and orientation of the source are consistent with it lying in the Rolandic fissure near or in the eye representation area of motor cortex.

Orientation selectivity of visual cortical neurons at different stimulus intensities in cats

Abstract: Orientation selectivity of 24 neurons in area 17 of the visual cortex at different intensities of test bars of light, flashing against a constant light background in the center of the receptive field, was investigated in acute experiments on immobilized cats. Five neurons were invariant in orientation tuning to stimulus intensity (contrast): Although the magnitude of the response and acuteness of orientation selectivity were modified, preferential orientation was unchanged. More than half of the cells studied (13) were classed as noninvariant, for their preferential orientation was significantly shifted by 22–90° with a change in contrast. Small shifts of the peak of orientation selectivity, not statistically significant, were observed for the other neurons. Invariant neurons, unlike noninvariant, were characterized by preferential horizontal and vertical orientation, a lower frequency of spontaneous and evoked discharges, and the more frequent presence of receptive fields of simple type. The mechanisms of the change of orientation selectivity during contrast variation and also the different use of the two types of cells in orientation detection operations are discussed.

An Investigation of the Development of Ocular Dominance and Orientation Columns in Cat Striate Cortex Using 2-Deoxyglucose

Abstract: Neurophysiological studies on the striate cortex of immature cats have indicated that although oriented neurones occur they are broadly tuned and have a more imprecise columnar organization. Similarly transneuronal autoradiography reveals an initially incomplete segregation of the geniculo-cortical afferents. We have used 2-deoxyglucose autoradiography to examine the development of columnar metabolic label in the striate cortex of normal and binocularly deprived kittens following either monocular stimulation or stimulation with fixed orientations. In normal animals, both orientation and ocular dominance columns achieve an adultlike pattern at 5–6 weeks of age and indications of periodic labelling in both stimulus conditions are first apparent at 3 weeks. After stimulation with fixed orientations at 3 weeks, discrete foci of increased labelling are seen in layer IV; it is only in older animals that a full columnar pattern appears. At 3 weeks, ocular dominance columns extend through all cortical layers both ipsilateral and contralateral to the stimulated eye; the columns become more regular in older animals. Binocular deprivation appears to inhibit the formation of orientation columns as defined by de-oxyglucose autoradiography; only in one 35 day old cat was there an indication of columnar labelling. Ocular dominance columns were less affected by binocular deprivation; at both 5 weeks and 3 months there was definite periodic label although the distribution in the younger animal was less regular than in a comparable normal animal.

[Correlation of topographic and spatial-frequency characteristics of the lateral suprasylvian region and the striate cortex in the cat].

Abstract: Modulation transfer functions and retinotopic organization of the two largest areas of visual projections in the cat cerebral cortex were determined and compared. Receptive fields of the neurons in the lateral suprasylvian area are large and their size rapidly increases with eccentricity. In spatial-frequency terms they are low-pass filters. Latent time of visual evoked potentials is shorter in the suprasylvian area than in the striate cortex. It means that low spatial frequencies are transferred more quickly in that area than high spatial frequencies in the striate cortex. Reciprocal connections of the two retinotopically organized areas may accomplish the correlation of high and low frequency descriptions occurring in them.