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D H Hubel

Publications and source records attributed to D H Hubel.

At least 19 recordsLinked to original sources
PubMed1995

Stereopsis and binocularity in the squirrel monkey.

The squirrel monkey lacks anatomically demonstrable ocular dominance columns, and physiologically it has an ocular dominance distribution in V1 that is very different from that of macaques, with far fewer cells that strongly favor one eye over the other. We tested an alert squirrel monkey for physiological responses to stereoscopic stimuli by measuring evoked potentials in response to cytclopean patterns generated in dynamic random-dot stereograms. The monkey showed evoked responses both to changes in disparity and to shifts between correlation and uncorrelation between the two eyes. This result strongly suggests that the squirrel monkey can detect stereoscopic depth, which in turn casts some doubt on the assumption that ocular dominance columns bear an important relation to stereopsis.

Animals↗
PubMed1994

Stereopsis and positional acuity under dark adaptation.

Though experience tells us we can perceive depth in dim light, it is not so obvious that one of the chief mechanisms for depth perception, stereopsis, is possible under scotopic conditions. The only studies on human stereopsis in the dark adapted state seem to be those of Nagel [(1902) Zeitschrift für Psychologie, 27, 264-266] and Mueller and Lloyd [(1948) Proceedings of the National Academy of Science, U.S.A., 34, 223-227], both of which used real objects or line stereograms. We tested stereopsis using both random-dot and line stereograms and, in agreement with these studies, found that stereopsis is indeed possible in dark adaptation. We also measured stereo acuity and positional acuity (both of which are examples of hyperacuity) and compared these with grating acuity at several levels of light and dark adaptation. At all illumination levels tested, acuities for stereopsis and relative line position were both higher than for grating acuity. As light levels decreased, positional and grating acuity declined in parallel fashion, whereas stereoacuity declined more steeply.

Dark Adaptation↗
PubMed1990

Color and contrast sensitivity in the lateral geniculate body and primary visual cortex of the macaque monkey.

We tested color and contrast sensitivity in the magnocellular and parvocellular subdivisions of the lateral geniculate body and in layers 2, 3, 4B, and 4C alpha of visual area 1 to obtain physiological data on the degree of segregation of the 2 pathways and on the fate of the color and contrast information as it is transmitted from the geniculate to the cortex. On average, magnocellular geniculate cells were much less responsive than parvocellular cells to shifts between 2 equiluminant colors. Nevertheless, many magnocellular cells (though not all) continued to give some response at equiluminance. As expected from previous studies, luminance contrast sensitivity differed markedly between magnocellular and parvocellular layers. In V-1, the properties of cells in the magnorecipient layers 4C alpha and 4B faithfully reflected the properties of magnocellular geniculate cells, showing no evidence of any parvocellular input. Like magnocellular geniculate cells, they showed high contrast sensitivity, and with color contrast stimuli they showed large response decrements at equiluminance. In the interblob regions of cortical layers 2 and 3, which anatomically appear to receive most of their inputs from parvorecipient layer 4C beta, contrast sensitivities of some of the cells were compatible with a predominantly parvocellular input. Other interblob cells had sensitivities intermediate between magno- and parvocellular geniculate cells, suggesting a possible contribution from the magnocellular system. Many cells in cortical layers 2 and 3 responded to color-contrast borders equally well at all relative brightnesses of the 2 colors, including equiluminance. We recorded from many direction- and disparity-selective cells in V-1: most of the direction-selective and all of the clearly stereo-selective cells were located in layer 4B.

Animals↗
PubMed1988

Do the relative mapping densities of the magno- and parvocellular systems vary with eccentricity?

Two recent papers on the macaque visual system have concluded that in the lateral geniculate body the ratio of the number of cells in the magnocellular system to the number in the parvocellular system representing the same area of visual field increases by a factor of 20 between the fovea and the far periphery. In the primary visual cortex the relative cell densities of the 2 systems change little with eccentricity. These calculations therefore predict a 20-fold change in the relative densities of the inputs to the visual cortex from the 2 subdivisions of the lateral geniculate body. To test this prediction, we asked if the following vary with eccentricity: (1) the ratio of the number of magnocellular to parvocellular neurons innervating a given area of striate cortex and (2) the relative density, in the magno- and parvo-recipient sublaminae of layer 4C, of radioactivity transported from the eye to the cortex. Neither of these ratios showed any significant variation with eccentricity. These results seem to throw doubt on the contention that the ratio between the magnocellular and parvocellular layers of the number of cells per degree2 of visual field varies significantly with eccentricity.

Animals↗
PubMed1987

Connections between layer 4B of area 17 and the thick cytochrome oxidase stripes of area 18 in the squirrel monkey.

In area 18 of the primate visual cortex, staining for the mitochondrial enzyme cytochrome oxidase reveals 3 types of stripelike subdivisions running perpendicular to the 17/18 border: thick, thin, and pale stripes. In a previous paper (Livingstone and Hubel, 1984), we described the anatomical connections with area 17 of 2 of these 3 subdivisions, but we did not have any conclusive information on the third subdivision, the thick stripes. Here we report that, in the squirrel monkey, the main input to the thick stripes from area 17 arises from layer 4B. Layer 4B receives its input from the magnocellular division of the lateral geniculate body by way of layer 4C alpha; the thick stripes therefore probably belong to the magnocellular subdivision of the visual pathway.

Animals↗
PubMed1987

Segregation of form, color, and stereopsis in primate area 18.

Primate visual cortical area 18 (visual area 2), when stained for the enzyme cytochrome oxidase, shows a pattern of alternating dark and light stripes; in squirrel monkeys, the dark stripes are clearly of 2 alternating types, thick and thin. We have recorded from these 3 subdivisions in macaques and squirrel monkeys, and find that each has distinctive physiological properties: (1) Cells in one set of dark stripes, in squirrel monkeys the thin stripes, are not orientation-selective; a high proportion show color-opponency. (2) Cells in the other set of dark stripes (thick stripes) are orientation-selective; most of them are also selective for binocular disparity, suggesting that they are concerned with stereoscopic depth. (3) Cells in the pale stripes are also orientation-selective and more than half of them are end-stopped. Each of the 3 subdivisions receives a different input from area 17: the thin stripes from the blobs, the pale stripes from the interblobs, the thick stripes from layer 4B. The pale stripes are thus part of the parvocellular system, and the thick stripes part of the magnocellular system. The physiological properties of the cells in the thin and pale stripes reflect the properties of their antecedent cells in 17, but nevertheless exhibit differences that suggest the kinds of processing that might occur at this stage.

Animals↗
PubMed1987

Psychophysical evidence for separate channels for the perception of form, color, movement, and depth.

Physiological and anatomical findings in the primate visual system, as well as clinical evidence in humans, suggest that different components of visual information processing are segregated into largely independent parallel pathways. Such a segregation leads to certain predictions about human vision. In this paper we describe psychophysical experiments on the interactions of color, form, depth, and movement in human perception, and we attempt to correlate these aspects of visual perception with the different subdivisions of the visual system.

Color Perception↗
PubMed1986

Effects of monocular exposure to oriented lines on monkey striate cortex.

This study examines the extent to which the restriction of visual experience to lines of a single orientation influences the organization of the striate cortex in infant monkeys (Macaca mulatta). Previous studies of kittens raised with monocular exposure to a single line orientation have consistently shown the response preference of cells driven by that eye to be biased towards the experienced orientation. Studies of binocular exposure to restricted orientations have been equivocal. In the infant monkey cortex responses to oriented lines have virtually all the specificity of responses seen in the adult animal. In an effort to clarify the phenomenon and the mechanism by which orientation bias might be obtained, we examined the effects of monocular exposure to a restricted orientation in infant macaques. Three monkeys were used. Each monkey was raised with one open eye exposed to lines of a single orientation and one eye occluded by lid suture. As in other cases of monocular deprivation in either cat or monkey, few binocularly driven cells were recorded and the majority of cells were dominated by the open eye. Cells driven by the open eye had normal representation of all orientation preferences and there was no overall increase in the number of cells preferring the orientation to which the eye had been exposed. The cells dominated by the occluded eye, however, showed a lack of cells responding to orientations to which the open eye had been exposed. These findings suggest that a competitive mechanism operates between the two eyes to provide an orientation selective advantage to the open eye.

Animals↗
PubMed1984

Anatomy and physiology of a color system in the primate visual cortex.

Staining for the mitochondrial enzyme cytochrome oxidase reveals an array of dense regions (blobs) in the primate primary visual cortex. They are most obvious in the upper layers, 2 and 3, but can also be seen in layers 4B, 5, and 6, in register with the blobs in layers 2 and 3. We compared cells inside and outside blobs in macaque and squirrel monkeys, looking at their physiological responses and anatomical connections. Cells within blobs did not show orientation selectivity, whereas cells between blobs were highly orientation selective. Receptive fields of blob cells had circular symmetry and were of three main types, Broad-Band Center-Surround, Red-Green Double-Opponent, and Yellow-Blue Double-Opponent. Double-Opponent cells responded poorly or not at all to white light in any form, or to diffuse light at any wavelength. In contrast to blob cells, none of the cells recorded in layer 4C beta were Double-Opponent: like the majority of cells in the parvocellular geniculate layers, they were either Broad-Band or Color-Opponent Center-Surround, e.g., red-on-center green-off-surround. To our surprise cells in layer 4C alpha were orientation selective. In tangential penetrations throughout layers 2 and 3, optium orientation, when plotted against electrode position, formed long, regular, usually linear sequences, which were interrupted but not perturbed by the blobs. Staining area 18 for cytochrome oxidase reveals a series of alternating wide and narrow dense stripes, separated by paler interstripes. After small injections of horseradish peroxidase into area 18, we saw a precise set of connections from the blobs in area 17 to thin stripes in area 18, and from the interblob regions in area 17 to interstripes in area 18. Specific reciprocal connections also ran from thin stripes to blobs and from interstripes to interblobs. We have not yet determined the area 17 connections to thick stripes in area 18. In addition, within area 18 there are stripe-to-stripe and interstripe-to-interstripe intrinsic connections. These results suggest that a system involved in the processing of color information, especially color-spatial interactions, runs parallel to and separate from the orientation-specific system. Color, encoded in three coordinates by the major blob cell types, red-green, yellow-blue, and black-white, can be transformed into the three coordinates, red, green, and blue, of the Retinex algorithm of Land.

Animals↗
PubMed1984

Specificity of intrinsic connections in primate primary visual cortex.

Several recent studies have suggested a patchy system of intrinsic lateral connections in area 17 of the macaque monkey. To see whether this pattern bore any relationship to the cytochrome oxidase blobs we made multiple tiny injections of horseradish peroxidase into layers 2 and 3 of area 17, small enough so that some of the injections (or their cores) were entirely inside a single blob, or entirely outside. When the injection centers were entirely in blobs, the label in layers 2 and 3 was transported preferentially to nearby blobs, avoiding nonblob areas. When the injections were in nonblob areas, the label was found predominantly in surrounding nonblob areas, avoiding the blobs. Besides this lateral transport, label was also present in the layers below 2 and 3: the label in layers 4 and 6 was very restricted, occupying roughly the diameter of the injection core and presumably representing axons of cell bodies at the injection site; in layer 5 diffusely labeled patches observed the same blob/nonblob segregation seen above layer 4.

Animals↗
PubMed1983

The 11th J.A.F. Stevenson memorial lecture. Blobs and color vision.

When the monkey striate cortex is stained for the mitochondrial enzyme cytochrome oxidase a polka-dot pattern of patches or blobs is observed in layers 2 and 3 and more faintly in layers 5 and 6. In the macaque these blobs are aligned along the centers of ocular dominance columns. Cells within blobs lack the orientation selectivity and instead have the simpler concentric center-surround fields common in geniculate cells. Blob cells are specifically concerned with color and in particular with maintaining color constancy despite marked changes in the spectral content of the light source.

Animals↗
PubMed1982

Thalamic inputs to cytochrome oxidase-rich regions in monkey visual cortex.

In primate primary visual cortex, staining for cytochrome oxidase reveals a regular array of blob-like structures, most prominent in layers II and III but also present in layers V and VI. In an attempt to learn more about the input to these blobs, we injected the lateral geniculate bodies of macaques and squirrel monkeys with [3H]proline or horseradish peroxidase and looked in the cortex for transported label. As expected, label was present in layers IVa, IVc alpha, IVc beta, and VI. In addition, both methods revealed an array of puffs deep in layer III. Seen in tangential sections, the puffs precisely matched the cytochrome blobs. These results indicate a projection from the lateral geniculate body to the blob regions deep in layer II/III, either indirect via layer IV or more likely direct. In area 18 stained for cytochrome oxidase, we also observed complex banding patterns; these were remarkably similar to the pattern found after [3H]proline or horseradish peroxidase injection and were also similar to the pattern produced with 2-deoxyglucose labeling after stimulation with vertical or horizontal stripes; the proline and peroxidase labels probably represent a projection from the pulvinar to area 18.

Animals↗