Showing papers on "Orientation column published in 1982"

Striate cortex of monkey and cat: contrast response function.

Abstract: 1. We measured the responses of 247 neurons recorded from the striate cortex of monkeys and cats as a function of the contrast intensity of luminance-modulated spatialtemporal sine-wave grating patterns to provide a qualitative description and a quantitative mathematical formulation of the contast response function (CRF). 2. Qualitatively, it is possible to provide a general description of the contrast response function for the majority of cells as follows: as the luminance contrast of a pattern increases, the response increases in a relatively linear fashion over approximately 50-607o of the response range (generally less than I log unit along the contrast range), the slope of the function then begins a rapid compression to an asymptotic maximum-saturation response level. There is, however, a great deal of variation. from cell to cell, in the exact shape and location of the CRF. 3. Quantitatively, the responses of each cell were analyzed in terms of the leastsquares (parameter optimized) best fit using four different mathematical functions: linear, logarithmic power, and hyperbolic ratio. The results of this procedure showed that, across the range of contrasts measured ( 1.4567o), the hypcrbolic ratio (H ratio) provided the best fit for the vast majority of striate cells: some 7O9o f the cells were best fitted by the H ratio and further, averaged across all cells, the H ratio produced the least average residual variance. 4. The contrast response function is an important factor when considering the spatial properties of cortical cells; nonlinearities in the CRF (compression and saturation) will necessarily influence the spatial tuning. We therefore measured the CRF at different spatial frequencies and used the parameters of the H ratio to test the predictions of two general classes of models. If the overall gain, compression, and saturation are set by the absolute response level (response-set gain), then the CRFs measured at different frequencies should shift horizontally along the contrast axis. Results show that the measured CRFs (tested on the same cell using different spatial frequencies) were shifted primarily vertically, suggesting that the gain, compression, and saturation were set by the absolute contrast level (contrast-set gain), relatively independent of spatial frequency; in terms of the H ratio, the semisaturation contrast and the exponent were relatively constant in comparison to the asymptotic saturation response. Thus, the spatial frequency response functions are relatively constant when measured at different stimulus contrasts. 5. There is a great deal of variation in the location of the dynamic response range, from cell to cell, along the contrast axis: some cells distribute their dynamic response range over the first lOVo of contrast, others the second, etc. (relatively independent of preferred spatial frequency). One might expect this range variation to be an important factor in behavioral contrast discrimination. To provide an indication of the average population response as a function of contrast, all cells were averaged together (percent response relative to each cell 's maximum): the slope of the bcst-fitt ing [nwer function (0.77) falls well within the range of estimates found for human psychophysical contrast discrimination functions.

Deoxyglucose analysis of retinotopic organization in primate striate cortex

Abstract: We have anatomically analyzed retinotopic organization using the 14C-labeled 2-deoxy-D-glucose method. The method has several advantages over conventional electrophysiological mapping techniques. In the striate cortex, the anatomical substrate for retinotopic organization is surprisingly well ordered, and there seems to be a systematic relationship between ocular dominance strips and cortical magnification. The 2-deoxyglucose maps in this area appear to be largely uninfluenced by known differences in long-term metabolic activity. This method should prove useful in analyzing retinotopic organization in various visual areas of the brain and in different species.

Orientation selectivity in the cat's striate cortex is invariant with stimulus contrast

Abstract: Extracellular responses of single units in striate cortex of the cat were studied quantitatively. Sinusoidal gratings were used as stimuli and the variables of interest were orientation and contrast. Specifically, we wanted to determine if orientation tuning was dependent on contrast. Of 45 cells studied in detail, two basic types of contrast-response pattern were observed, but most patterns were intermediate between these extremes. In one type, responses increased approximately linearly with log contrast while in the second, saturation was found at low contrast levels. For all these cells, orientation tuning characteristics were independent of contrast. An additional observation, made from 14 cells, was that stimuli presented at non-optimal orientations can suppress responses to below the general maintained discharge levels. In eight of these cases, the inhibition was clearly contrast-dependent.

Widespread periodic intrinsic connections in the tree shrew visual cortex

Abstract: Intrinsic connections within the tree shrew (Tupaia glis) visual cortex (area 17) are organized in periodic stripelike patterns within layers I, II, and III. This anatomical network resembles the regularly organized stripes of 2-deoxyglucose accumulation seen after stimulation of alert animals with uniformly oriented lines. Such connections imply that widespread lateral interactions are superimposed on the retinotopic organization of area 17 and suggest alternative interpretations of cortical columns.

The laminar organization of the lateral geniculate body and the striate cortex in the squirrel monkey (Saimiri sciureus)

Abstract: The organization of the projection from the lateral geniculate body to the striate cortex in the squirrel monkey has been re-examined using the anterograde and retrograde transport of horseradish peroxidase (HRP) and wheat germ agglutinin conjugated to HRP. The results confirm earlier findings that the projections of the magnocellular and parvocellular layers of the lateral geniculate body terminate in separate sublaminae of layer IV of striate cortex; a more superficial projection of the parvocellular layers to a narrow strip at the base of layer III (IVA in Brodmann's terminology) has also been confirmed. In addition to these well characterized pathways, our results show that the projections of the lateral geniculate body terminate in more superficial levels of layer III and sparsely in layer I of striate cortex. The projections to the upper portion of layer III terminate in distinct patches which coincide precisely with patches of cytochrome oxidase activity previously identified in this zone. The projections to the patches originate primarily from small, pale-staining cells of the "intercalated layers" which surround the magnocellular layers of the lateral geniculate body. A comparison of the organization of the geniculo-cortical projections in the squirrel monkey with that of the cat, Galago, and Tupaia suggests that, despite marked species differences in the laminar organization of the lateral geniculate body and striate cortex, there are striking similarities in the pathway which terminates in the most superficial layers of striate cortex.

Effect of cooling area 18 on striate cortex cells in the squirrel monkey.

Abstract: 1, Retinotopically corresponding regions of area 17 and area 18 are reciprocally connected in the squirrel monkey (Saimiri sciureus) (15, 17, 20). Area 17 is known to provide a crucial input to area 18 in the macaque (1 X), but the function of the pathway from area 18 to striate cortex has not been investigated. We chose to study this pathway in the squirrel monkey by reversibly cooling area 18 while recording from cells in area 17. 2. Cells were recorded in striate cortex in paralyzed anesthetized squirrel monkeys before, during, and after cooling the corresponding region of area 18 to 9-20% Thirty-two percent (21/66) of the cells recorded in striate cortex showed marked changes in activity when area 18 was cooled. Most of these became less responsive to visual stimulation, while a few became more active during cooling. All changes were reversed by rewarming area 18 to body temperature. 3. No changes in orientation selectivity were observed in striate cortex when area 18 was cooled. Direction selectivity was only occasionally altered and involved the emergence of a new response to stimulation in the previously nonpreferred direction. 4. Cells in striate cortex affected by cooling area 18 were found most often in the infragranular layers, although they were also observed in the sublaminae of layer III and in layer IV. The concentration of affected cells in the infragranular layers suggests that area 18 may use this pathway to modulate the output of striate cortex to subcortical visual centers.

Long axons within the striate cortex: their distribution, orientation, and patterns of connection.

Abstract: Rockland and Lung [Rockland, K. S. & Lung, J. S. (1982) Science 215, 1532-1534] have recently observed that an injection of horseradish peroxidase into the striate cortex of the tree shrew produces a patchy distribution of label adjacent to the injection site. They proposed that this pattern might be due to populations of neurons with long-range cortico-cortical connections that are interspersed with populations having no such connections. We suggest here an alternative explanation. We can account for the pattern by supposing that the label is carrier by a system of oriented axons. We suppose that these axons link cells with similar orientation preferences and make their connections within a narrow strip of cortex whose direction is related to the orientation of the cells in question. We suggest that such connections could be involved in generating complex receptive fields from simple ones. Other possibilities are that they are used to generate very elongated receptive fields, inhibitory flanks, or end-stopping. We suggest a number of experimental tests of these ideas.

A model for the formation of orientation columns.

Abstract: A mathematical model is proposed to describe the formation of orientation columns in mammalian visual cortex. The model is similar in concept to that proposed for ocular dominance column formation (Swindale 1980), the essential difference being that orientation is a vector rather than a scalar variable. It is assumed that initially orientation selectivity is weak and randomly distributed, and that selectivity develops in such a way that the orientation preferences of neurons less than about 200 microns apart tend to change in a similar direction, whereas the preferences of cells further apart tend to develop in opposite directions. No hypotheses are made about the anatomical or physiological basis of these interactions, and it is not necessary to assume that they are the result of environmental stimulation, as with existing models for the development of orientation selectivity (see, for example, von der Malsburg, 1973). The model reproduces the experimental data on orientation columns: roughly linear sequences of orientation change are produced, and these alternate unpredictably between clockwise and anticlockwise directions of change. Continuous sequences may span several 180 degrees cycles of rotation. The sequences are generally smooth, but abrupt discontinuities of up to 90 degrees also occur. The iso-orientation domains for large orientation ranges (60-90 degrees) are periodically spaced branching stripes that resemble those demonstrated in animals by the 2-deoxyglucose technique. The domains for narrower orientation ranges are periodically spaced but are more irregular in shape, though sometimes thin and elongated. The model makes a number of predictions that can be tested experimentally. Of particular interest are the discontinuities in the orientation sequences: these should be distributed with a spacing roughly equal to, or half, that of the iso-orientation domains. Each should be surrounded by one or two complete sets of iso-orientation domains, and each may be associated with regions where cells are not orientation selective. These regions may be more extensive in younger animals, when the columns are at an intermediate stage of formation, and less numerous where the columns run parallel and unbranched over large areas.

Cortical connections of striate cortex in the owl monkey

Abstract: Injections of tritiated proline and horseradish peroxidase were used to study cortical connections of striate cortex in owl monkeys. All cases resulted in label in area 18 (V-II) and the middle temporal visual area (MT). In most, but not all cases, label was also present in the dorsomedial visual area (DM). The connections between striate cortex and each of these three visual areas were retinotopic and reciprocal. Projections to V-II, MT, and DM were concentrated in layers IV and III, while pyramidal cells in layers III, V, and VI of these areas projected back to striate cortex.

A model of the early stages of the human visual system: Functional and topological transformations performed in the peripheral visual field

Abstract: A model of the early stages of the visual system is presented, with particular reference to the region of the visual field outside the fovea and to the class of retinal and lateral geniculate nucleus cells which are most active in the processing of pattern information (X-cells). The main neuroanatomical and neurophysiological properties taken into account are: the linear increase of the receptive fields diameter with eccentricity, the constancy of the overlap factor and the topological transformation operated upon the retinal image by the retino-cortical connection. The type of filtering taking place between the retina and the visual cortex is analyzed and some simulations are presented. It is shown that such a filtering is of a band-pass space variant type, with center frequencies that decrease from the center (i.e. the fovea) toward the periphery of the visual field. This processing is "form invariant" under linear scaling of the input. Moreover, considering the properties of the retino-cortical connection, it is shown that the "cortical images" undergo simple shifts whenever the retinal images are scaled or rotated.

Central core control of developmental plasticity in the kitten visual cortex: I. Diencephalic lesions.

Abstract: In five, dark-reared, 4-week-old kittens the posterior two thirds of the corpus callosum were split, and a lesion comprising the intralaminar nuclei was made of the left medial thalamic complex. In addition, the right eye was closed by suture. Postoperatively, the kittens showed abnormal orienting responses, neglecting visual stimuli presented in the hemifield contralateral to the side of the lesion. Sudden changes in light, sound, or somatosensory stimulation elicited orienting responses that all tended toward the side of the lesion. These massive symptoms faded within a few weeks but the kittens continued to neglect visual stimuli in the hemifield contralateral to the lesion when a second stimulus was presented simultaneously in the other hemifield. Electrophysiologic analysis of the visual cortex, performed after the end of the critical period, revealed marked interhemispheric differences. In the visual cortex of the normal hemisphere most neurons were monocular and responded exclusively to stimulation of the open eye, but otherwise had normal receptive field properties. In the visual cortex of the hemisphere containing the thalamic lesion, the majority of the neurons remained binocular. In addition, the selectivity for stimulus orientation and the vigor of responses to optimally aligned stimuli were subnormal on this side. Thus, the same retinal signals, which in the control hemisphere suppressed the pathways from the deprived eye and supported the development of normal receptive fields, failed to do either in the hemisphere containing the thalamic lesion. Apparently, experience-dependent changes in the visual cortex require both retinal stimulation and the functioning of diencephalic structures which modulate cortical excitability and control selective attention.

Some topographical connections of the striate cortex with subcortical structures in Macaca fascicularis

Abstract: Subcortical connections of the striate cortex with the superior colliculus (SC), the lateral pulvinar (Pl), the inferior pulvinar (Pi) and the dorsal lateral geniculate nucleus (LG) were studied in the macaque monkey, Macaca fascicularis, following cortical injections of tritiated proline and/or horseradish peroxidase. All four structures were shown to receive topographically organized projections from the striate cortex. The exposed surface of the striate cortex was found to be connected to the rostral part of the SC and the caudal part of the LG. Injections of the exposed striate cortex close to its rostral border resulted in label in adjoining parts of the Pl and Pi. The ventral half and dorsal half of the calcarine fissure were connected with the medial and lateral parts of the SC, the ventrolateral and dorsomedial portions of the Pl and Pi and the lateral and medial parts of the LG, respectively. Injections located at the lateral posterior extreme of the calcarine fissure resulted in label at the optic disc representation in the LG. The horseradish peroxidase material demonstrated that LG neurons in all laminae and interlaminar zones project to the striate cortex.

Alterations of retinal inputs following striate cortex removal in adult monkey

Abstract: The morphology of the retina and central retino-recipient nuclei was studied in two monkeys that had undergone total bilateral striate cortex removal as adults. These animals had been behaviorally tested for two years after lesioning and had demonstrated significant recovery of pattern vision. Light and electron microscopy and autoradiography were done on the central retino-recipient nuclei following a monocular intravitreal injection of 3H-proline. Light microscopic analysis of retinal ganglion cell number showed a 30% loss in the parafoveal retina due to retrograde trans-synaptic degeneration. The most striking central change in retinal axon distribution was in the dorsal lateral geniculate nucleus (dLGN) where the parvocellular but not the magnocellular region showed a marked reduction in retinal input. Despite the loss of almost all dLGN neurons through retrograde degeneration, at the EM level both parvocellular and magnocellular regions contained islands of neuropil made up of retinal and several other types of synaptic terminals as well as small dendrites and pale unidentified processes. Approximately equal numbers of retinal terminals were identified by EM autoradiography in both regions of dLGN, which did not explain the apparent differences in labeling between the two regions seen in the light microscope. A second change in central retinal pathways was found in the olivary pretectal nucleus where a significant loss of retinal input also occurred. A third change, but in the opposite direction, was found in the pregeniculate nucleus (PGN) where the area of retinal terminals appeared enlarged. The remaining central retino-recipient nuclei had the same distribution of retinal input as the control animals.

Receptive-field transformations between LGN neurons and S-cells of cat-striate cortex.

Abstract: 1. To determine the functional transformation in the processing step between lateral geniculate nucleus (LGN) and striate cortex, the receptive-field characteristics of 50 directly driven, lamina 4 S-cells were compared with those of a similar number of LGN neurons. Experiments were performed on paralyzed and anesthetized adult cats. 2. A signature was established for the responses of LGN neurons by observing the responses to thin light and dark moving bars and, after allowing for latency, by comparing these responses with the flashing-bar receptive field. Evidence of this signature was then sought in the responses of S-cells to similar stimuli. 3. When stimulated with moving bars, on-center LGN neurons responded with a strong discharge to a light bar followed, in spatial position, by a discharge to a dark bar. When compared to the flashing-bar receptive field, the light-bar discharge corresponded with the near side of the receptivefield center and the dark-bar discharge with the far side. Off-center LGN neurons generally gave a complementary pattern to the one above. Brisk sustained (BS) and brisk transient (BT) LGN units showed similar results. 4. By identifying the signature of LGN neurons in the responses of S-cells it was possible to recognize at least two and possibly three arrangements in the inputs to these cells. Individual S-cell responses could be explained as arising from: a) a single type (onor off-center) of LGN neuron, b) two types (onand off-center) of LGN neurons with their receptive fields placed side by side along the line orthogonal to the optimal orientation, c) three types of LGN neuron. Only a small number of S-cells were placed in the c category. There is doubt about the existence of the tripartite input, since in certain respects the responses of these cells resembled those of cells receiving a single or dual input. In all three groups, S-cells were found receiving inputs from either the fast (BT) or slow (BS) stream. 5. In the population of dual-input S-cells, the separation between the centers of onand off-responses distributed over a range similar to that found for the diameters of the receptive-field centers in parent LGN neurons. This was the case for cells in either the fast (BT) or slow (BS) streams. 6. Along the line parallel to the optimal orientation the receptive-field length of Scells, measured by the method of length summation, ranged over a distance twice that of the receptive-field center diameters in the parent LGN neurons. 7. An estimate was made of the number of LGN neurons contributing to the receptive fields of single S-cells in lamina 4. After making certain assumptions about the distributions of inputs to the S-cell receptive field, it was estimated that the response in each discharge region came from 1 to 20 like LGN neurons. It is argued that the receptive-field midpoints of these afferents are scattered over a circular area, whose diameter is equal to the receptive-field center diameter of one of the afferent LGN neurons (0.4” for BS and 0.8O for BT neurons).

On the sensitivity of complex cells in feline striate cortex to relative motion.

Abstract: Responses of superficial-layer, texturesensitive complex cells in cat striate cortex to relative motion between an oriented bar stimulus and its textured background were recorded. Some cells responded best to motion in one particular direction across the receptive field of the cell, irrespective of whether the bar and background moved simultaneously in the same (in-phase) or opposite (antiphase) directions. Others showed a clear preference for either in-phase or antiphase relative motion, irrespective of direction of motion across the receptive field.

Functional organization of neurons in cat striate cortex: variations in ocular dominance and receptive-field type with cortical laminae and location in visual field.

Abstract: 1. Binocularity and receptive-field type of cortical neurons were assessed relative to the cortical layer in which the neurons were recorded and to receptive-field position in the visual field. 2. ...

A high probability of an orientation shift between layers 4 and 5 in central parts of the cat striate cortex.

Abstract: On the postlateral gyrus of the cat striate cortex the cells' preferred orientation was measured as a function of cortical depth in penetrations as parallel as possible to the radial fibre bundles. According to the penetration angle and in agreement with the current model of orientation columns, there was a low orientation drift in layers 2–4. At the transition between layers 4 and 5 an orientation shift of 45–90 deg was found in most penetrations. The orientation differences between adjacent recording sites in lower layers was normally low too, but clearly higher than in upper layers. The results are discussed in terms of more independent orientation mechanisms in upper and lower layers.

Projections of the dorsal lateral geniculate and lateral posterior nuclei to visual cortex in the rabbit.

Abstract: The origin and terminations of thalamic inputs to the striate cortex and the occipital cortex of the rabbit were studied using both anterograde autoradiographic techniques and retrograde transport of horseradish peroxidase (HRP). After injections of [3H]-leucine into the dorsal lateral geniculate nucleus (DLGN) the transport of radiolabeled material was demonstrated in separate loci in both the striate and the occipital cortex. In both these cortical areas, the principal site of geniculocortical termination was in lamina IV with some diminished input spreading into laminae II-III and a light termination in layer I overlying the lamina IV termination. Layer VI of striate cortex received a substantial projection from DLGN while infragranular laminae of occipital cortex received a similar although lighter and more diffuse projection. The lateral posterior nucleus (LPN) was similarly demonstrated to project to both striate and occipital cortices, the projection terminating principally in lamina IV of occipital cortex, lamina V of striate cortex, and layer I over a large, continuous area of the posterior pole of the cortex. Moreover, a projection from LPN to the retrosplenial cortex medial to the striate area was consistently seen. The autoradiographic demonstration of a projection from DLGN and LPN to both striate cortex and occipital cortex was corroborated by the retrograde studies. Following the injection of HRP into either the striate or occipital cortex, columns of retrogradely filled somata were identified in both the DLGN and LPN. The location of the column of labeled neurons within each nucleus varied predictably with the location of the injection in either the striate or the occipital cortex.

Structure of columns in monkey striate cortex induced by luminant-contrast and color-contrast stimulation.

Abstract: Color and black and white line stimulation produce qualitatively and quantitatively different 2-deoxy[14C]glucose column patterns in the striate cortex of macaque monkeys. Microdensitometry of these stimulus-dependent columns reveals interlaminar density differences that serve as a signature for the stimulus conditions which produced them. Such columns are individually distinct and form a three-dimensional mosaic throughout striate cortex.

Single unit receptive fields in rabbit primary binocular cortex

Abstract: The receptive fields of 125 single units recorded from the binocular region of rabbit primary visual cortex have been analysed. The population of 43% radially symmetric, 23% directional, and 23% orientation selective units is similar to that of rabbit monocular visual cortex. The relative scarcity of orientation selective units and the absence of orientation columns differentiates rabbit from cat primary visual cortex. However, the majority of binocular units had similar receptive fields in each eye and very unconventional receptive fields were not encountered. Tested binocular units demonstrated summation upon simultaneous stimulation of both receptive fields. In conjunction with findings reported elsewhere, these results suggest that rabbit and cat possess a similar provision for binocular vision in spite of some differences in their cortical organisation.

Dynamics of the receptive fields of visual cortex and lateral geniculate body neurons in the cat

Abstract: The dynamics of receptive fields of the visual cortex and lateral geniculate neurons were investigated in acute experiments on unanesthetized immobilized cats. For this purpose a computer presented small local flashes in a random order to 100 points of the receptive field and changes in three-dimensional relief of activity within the field were evaluated every 20 ms. Regular dynamic reorganizations of registered receptive fields of all investigated neurons were observed both after switching on and off the light stimulus. After the latency a small region of weak responses appeared in the centre of field. Later on the recorded field enlarged gradually, reaching maximal size at 60-100 ms, and after that began to narrow and disappeared or fell to pieces. The central inhibitory zone of the field had the same dynamics. If the neuron responded to stimulation by generating two bursts of spikes, during the second one the receptive field changed in the same way. The effect was revealed under various conditions of light stimulation. Functional significance of these effects for orientational information coding by visual cortex neurons is discussed.