Showing papers on "Orientation column published in 1975"

Receptive fields of single cells and topography in mouse visual cortex.

Abstract: The visual cortex was studied in the mouse (C57 Black/6J strain) be recording from single units, and a topographic map of the visual field was constructed. Forty-five percent of the neurons in striate cortex responded best to oriented line stimuli moving over their receptive fields; they were classified as simple (17%), complex (25%) and hypercomplex (3%). Of all preferred orientations horizontal was most common. Fifty-five percent of recpetive fields were circularly symmetric: these were on-center (25%), off-center (7%) and homogeneous on-off in type (23%). Optimal stimulus velocities were much higher than those reported in the cat, mostly varying between 20 degrees and 300 degrees/sec. The field of vision common to the two eyes projected to more than one-third of the striate cortex. Although the contralateral eye provided the dominating influence on cells in this binocular area, more than two-thirds of cells could also be driven through the ipsilateral eye. The topography of area 17 was similar to that found in other mammals: the upper visual field projected posteriorly, the most nasal part mapped onto the lateral border. Here the projection did not end at the vertical meridian passing through the animal's long axis, but proceeded for at least 10 degrees into the ipsilateral hemifield of vision, so that at least 20 degrees of visual field were represented in both hemispheres. The magnification in area 17 was rather uniform throughout the visual field. In an area lateral to area 17 (18a) the fields were projected in condensed mirror image fashion with respect to the arrangement of area 17. Medial to area 17 a third visual area (area 18) was again related to 17 as a condensed mirror image.

The pattern of ocular dominance columns in macaque visual cortex revealed by a reduced silver stain.

Abstract: A pattern of alternative dark and pale bands was observed in the straite cortex of the macaque monkey. The bands, which ran parallel to the surface, were seen in tangential sections stained with a reduced silver method for normal fibers and were most clear in layer 4C α, immediately deep to the line of Gennari. The dark bands were about 300 μ wide and showed blind endings and bifurcations. The light bands were about 50 μ wide and did not branch or terminate within area 17. Because the dark bands were similar in width to the bands of terminal degeneration which have been shown to result from single-layer lesions of the lateral geniculate body, it seemed possible that they corresponded to ocular dominance columns. To test this idea, the boundaries of ocular dominance columns were marked in a physiological experiment: tangential electrode penetrations were made in an anesthetized monkey and, as the electrode was advanced horizontally in the fourth layer, the eye preference of single units and of the background activity was monitored. Small electrolytic lesions were placed at the points where a change in eye preference occurred. The brain was subsequently fixed, sectioned tangentially and stained with the silver method. All the lesions — a total of 12 — fell directly on the pale bands. Moreover, the electrode had not passed over any pale bands without a lesion being placed. It was concluded that the dark bands do correspond to single ocular dominance columns and the pale bands to the boundaries between columns. The banding appearance is due to a greater density of tangential fibers within columns than at the borders of columns. These tangential fibers are in part the preterminal arborizations of geniculocortical axons, since some of them have been shown to degenerate after geniculate lesion. The ocular dominance columns were mapped for most of the striate cortex, using serial tengential sections stained with the silver method. The overall pattern was similar in several monkeys, though the details of the branching arrangements vaired from animal to animal. The columns met the 17–18 border at rigtht angles. On the outer surface of the hemisphere the columns converged from the 17–18 border, turned medially with repeated fusions of columns, and streamed over the lip of the calcarine fissure. In the roof of the fissure they met a second system of columns oriented parasagittally. In terms of the visual field, the columns ran roughly horizontally for the central 10° of the field, and circumferentially beyond that. The columns were not mapped in the stem of the fissure, the area corresponding to the far periphery of the field. The constancy of column width across the cortex probably allows a functional matching between ocular-dominance and orientation columns.

Visual activation of neurons in inferotemporal cortex depends on striate cortex and forebrain commissures.

Abstract: Neurons in inferotemporal cortex respond only to visual stimuli and a majority have receptive fields that extend well into both visual half-fields. After bilateral removal of striate cortex, no inferotemporal neurons responded to visual stimuli. After unilateral removal of striate cortex, inferotemporal neurons in both hemispheres responded only to stimuli in the hemifield contralateral to the intact striate cortex. After section of the corpus callosum and anterior commissure, inferotemporal neurons in both hemispheres responded only to stimuli in the hemifield contralateral to the recording site. These results indicate that inferotemporal cortex visual information from striate cortex and that the pathway from striate cortex to the contralateral inferotemporal cortex includes the forebrain commissures. This same striate-temporal pathway is also necessary for normal discrimination learning. We suggest that the converging input onto single inferotemporal neurons from widely separated retinal areas may provide a mechanism for stimulus equivalence over different parts of the visual field, and it may be the absence of such a mechanism that contributes to the visual discrimination deficit that follows inferotemporal lesions.

Afferent-efferent linkages in motor cortex for single forelimb muscles.

Abstract: 1. In locally anesthetized cats, extracellular recordings were made from single neurons in the lateral cruciate gyrus of cerebral cortex. These neurons responded to natural activation of stretch re...

Neural plasticity in visual cortex of adult cats after exposure to visual patterns.

Abstract: Over a period of 2 weeks, adult cats were twice a day exposed for 1 hour to a visual environment consisting only of vertical stripes and for the rest of the time were kept in darkness. Subsequent investigation of the striate cortex showed a decrease in the number of neurons sensitive to orientations around the vertical relative to those sensitive to horizontal orientations. This indicates that plasticity of functional properties of the cortical neuronal network still exists in adult animals.

Ontogenesis of receptive field characteristics in the dorsal lateral geniculate nucleus of the rabbit

Abstract: The responses of rabbit dorsal lateral geniculate neurons to light or optic nerve shock were tested for 415 units in 43 rabbit pups 2--20 days of age. Units were driven by optic nerve shock at the youngest ages tested, but could not be driven by light until postnatal day six. Examples of each of the three prominent categories of receptive fields found in the adult were first observed at 8 days of age. Cells with receptive field properties not characteristic of the dorsal lateral geniculate nucleus of the adult were encountered until 17 days of age. The percentage of neurons with uniform and motion sensitive receptive fields approached adult levels soon after eye opening (11--12 days) but the percentage of cells with concentric receptive fields showed a steady increase throughout the neonatal period studied. The relevance of our data to the development of the visual response in the dorsal lateral geniculate nucleus and striate cortex is discussed.

Development of cat visual cortex following rotation of one eye

Abstract: EVER since the first description of the optical inversion of images within the vertebrate eye, philosophers and psychologists have pondered the question of how animals interpret the directions of objects in space. The physiological discovery of retinotopic ‘maps’ in the brain (such that the retina is represented in an orderly array in the tectal1 and cortical2 visual areas) seemed to provide an answer to the question. Neurones in these visual centres have receptive fields that are restricted to a particular region of the retina and could therefore preserve information concerning the positions of objects in the visual world.

Responses of striate cortical cells to moving edges of different curvatures

Abstract: The responses of twenty cells to stimuli of varying curvature were measured in cat's striate cortex. All the investigated cells were sensitive to the orientation of lines and not hypercomplex. Fourteen cells showed a systematic change of response with curvature. The optimal curvatures of the cells were distributed over the whole range investigated. Six cells were insensitive to curvature. The responses from all the typical simple cells (8) varied with curvature, whereas all the complex cells (5) were insensitive to curvature changes. The curvature tuning curves were broad and the variability to individual stimuli was high, independent on whether the cell responded best to straight or to curved edges. The findings do not support the view that individual cells of area 17 could detect curvature.