Showing papers on "Receptive field published in 1972"

Relay of receptive-field properties in dorsal lateral geniculate nucleus of the cat.

Abstract: THE DORSAL lateral geniculate nucleus (LGNd) of the cat is a principal relay nucleus on the direct pathway from the retina to the visual cortex, and several parameters of its organization as a relay are well established. First, relay cells of the LGNd have either onor off-center receptive fields (16), because each relay cell receives direct excitatory drive from either onor off-center retinal ganglion cells (6, 16). Second, retinal ganglion cells fall into two groups (X-cells and Y-cells) according to whether they sum the influences of the center and surround regions of their receptive fields linearly or nonlinearly (8). Most LGNd relay cells can be similarly classified because most receive direct excitatory drive from either Xor Y-type retinal ganglion cells (6). Third, each relay cell receives direct excitatory drive from either fastor slow-conducting retinal afferents, and its own axon is correspondingly either fast or slow conducting (6, 36). The two latter parameters are closely correlated since Y-cells have been shown to have fast axons and Xcells, slow axons (6, 11). The on/off organization is independent of the other two parameters, however. Roth Y-cells and Xcells can have either onor off-center fields. This report examines several features of the LGNd relay in the normal cat, extending previous concepts and establishing a spectrum of normal properties against which the properties of the LGNd in deprived cats (described in the following paper (3W can be compared. First, the separate relay in the LGNd of the Xand Y-cell activity of the retina is described. Second, several properties of Xand Y-cells of the LGNd were observed to vary con-

Loss of a specific cell type from dorsal lateral geniculate nucleus in visually deprived cats.

Abstract: cATs REARED under various conditions of visual deprivation are deficient in their subsequent performance of certain visual tasks (6, 19). Wiesel and Hubel (15-17, 25-28) have sought the physiological basis of these effects by comparing receptivefield properties of single visual neurons of normhlly reared cats to those of visually deprived cats. Their consistent finding (17, 26-28), confirmed by others (7), is that cells of the striate cortex develop permanently abnormal receptive-field properties during deprivation rearing. In a preliminary study, Wiesel and Hubel (25) observed that cells of the dorsal lateral geniculate nucleus (LGNd) in visually deprived cats have essentially normal receptive fields despite the loss of many large cells in this nucleus. These findings have been subtantially confirmed (11, 24). The present studv which follows note the a series presence of of t recent wo funct papers ionallv distinct types of cell in the cat’s retina and LGNd: the X-cells (3, 13) (type II (5, 21) or sustained cells (2)) and the Y-cells (3, 13) (type I (5, 21) or transient cells (2)). This paper presents evidence that one effect of rearing cats with visual deprivation (achieved by neonatal eyelid suture) is the selective elimination from the LGNd of Y-cells. The remaining neurons appear to be functionally normal.

Receptive field organization of `sustained' and `transient' retinal ganglion cells which subserve different functional roles

Abstract: 1. Post-stimulus histograms were obtained from ;sustained' and ;transient' retinal ganglion cells for receptive field plots using a light spot with square-wave modulation of intensity, and of variable intensity and area. Fundamental differences in their receptive field organization in time and space were revealed.2. In ;sustained' cells, excitation consists of ;transient' and ;sustained' components and the ratio of transient/sustained components remains constant at a given retinal locus for a wide range of intensities. The transient component becomes proportionally larger towards the periphery of the receptive field. This rule is also applicable for the inhibitory and disinhibitory surround. In ;transient' cells, however, there is no true ;sustained' component, but some cells produce a double peaked transient post-stimulus histogram at the R.F. centre when high flux stimuli are used, while others show a single peak transient response. The magnitude and shape of transient responses changes with intensity as well as with location in the receptive field.3. The sensitivity gradients of ;sustained' and ;transient' cells show consistent differences in shape. The mean slope of the sensitivity gradients of a sample of ;sustained' cells was 10 times that of a sample of ;transient' cells. The sensitivity gradient of ;sustained' cells shows a distinct surround region where the inhibitory mechanism is more sensitive, while that of ;transient' cells usually does not, owing to an extensive ;tail' on the sensitivity gradient of the centre mechanism, which overlaps the surround.4. Ricco's Law also holds for the centre mechanism of ;transient' cells. Non-linear summation occurs at supra-threshold levels, and when the surround mechanisms are involved.5. Supra-optimal stimuli give a saturation of the response in both ;transient and ;sustained' cells. This saturation is associated with a decrease of latency in ;transient' cells, but not in ;sustained' cells.6. The latency of retinal ganglion cells is determined by both stimulus and background flux. The effect of the background is negligible except at low values of stimulus flux, where its effect may be analysed primarily in terms of its effect on the incremental threshold.7. The latency to stimulation with a standard small spot (25-27') at the receptive field centre is shorter for ;sustained' cells than for ;transient' cells; this latency difference being related to the greater sensitivity of the ;sustained' cells to stimuli of this size. Differences in conduction time along ;transient' and ;sustained' pathways to the lateral geniculate nucleus (LGN) and cortex were estimated, and it is concluded that despite the latency difference noted above, a response to a stimulus which is optimal for a ;transient' cell reaches the cortex faster than the response to a stimulus which is optimal for a ;sustained' cell.8. The above results together with previous evidence available suggest that for most stimuli, centre and surround mechanisms are activated simultaneously and algebraically summed by a single linear stage in ;sustained' cells. In ;transient' cells, although the centre excitation and surround inhibition pools are also spatially co-extensive, they summate and interact in time and space with a greater complexity.9. Differences in the receptive field organization of ;sustained' and ;transient' cells may reflect their different functional roles in vision: (1) analysis of spatial contrast and form recognition (;sustained' cells), and (2) fast detection of objects entering visual space to cause orientation responses (;transient' cells).

Cortical Visual Areas and Their Interactions

Abstract: Of all the sensory systems, the visual system is probably the best understood. Yet even for vision we still know very little about central mechanisms, about what happens after retinal impulses reach the striate cortex. The discovery some years ago that there is a visual area in the temporal lobe (Chow, 1951; Mishkin, 1954) opened up this black box a little. At least it made it clear that vision does not begin and end in the striate cortex as Lashley (1948) believed he had demonstrated. But what role the inferior temporal cortex plays in vision, and how it plays this role, have proved to be extremely baffling questions. I should like here to pursue these questions by bringing together some new evidence on the nature of the visual functions of the inferior temporal cortex and of the neural mechanisms on which these functions depend. My goal will be to develop a scheme for the way in which the cortical visual areas — the striate, the prestriate, and the inferotemporal — might interact to form a single, extended, cortical visual system. To begin, I shall describe some experiments I did in collaboration with Eiichi Iwai (Iwai and Mishkin, 1968), who was in our laboratory recently as a visiting scientist from Fukushima Medical College, Japan.

Comparison of receptive-field organization of the superior colliculus in Siamese and normal cats.

Abstract: 1. The superior colliculus has been studied in Siamese and normal cats by recording the responses of single tectal units to visual stimuli. 2. The retinotopic organization of the superior colliculus has been compared in the two breeds. In the normal cat, the contralateral half-field is represented in the central and caudal part of the colliculus, and a vertical strip of the ipsilateral half-field, 15–20° wide, is represented at the anterior tip. The Siamese cat superior colliculus receives an abnormally large projection from the ipsilateral half-field so that units with visual receptive fields which extend as far as 40° into the ipsilateral half-field can be found. The area of the tectal surface devoted to the representation of the ipsilateral half-field is about twice as large in Siamese cats as in normal cats. The enhanced representation of the ipsilateral half-field in Siamese cats is reflected in a displacement of the vertical meridian and the area centralis on the tectal surface. 3. The area centralis in the Siamese cat is located at about the same point on the tectal surface as would be occupied by a point in the visual field about 6–7° contralateral to the area centralis in the normal cat. The smallest receptive fields in both breeds are located near the area centralis. The size of the receptive field for a tectal unit seems to be determined by the retinal location of the receptive field and not by the absolute position of the unit on the tectal surface. 4. The receptive-field characteristics of tectal units show many similarities in the two breeds. The receptive fields of individual units consist of activating regions flanked by suppressive surrounds. Units respond well to stimuli of different shapes and orientation provided they are moving. The optimum stimulus for a given unit can be much smaller than the size of the activating region. About two thirds of the units studied in both breeds show directional selectivity. Most of the units studied in normal cats can be activated by stimulation of either eye, while in Siamese cats, 80% of the units studied can be driven only by the contralateral eye. A few monocularly driven units with two separated receptive fields have been observed in Siamese cats. 5. In the left tectum of both breeds, units respond well to left-to-right stimulus movement. The reverse situation obtains in the right tectum. In Siamese cats, units located at the anterior tip of the tectum with their receptive fields located in the visual half-field ipsilateral to the tectum under study respond better to stimulus movement toward the area centralis than away from it. The preferred direction for a tectal unit seems to be determined by its tectal location rather than by the location of its receptive field in the retina. 6. Visual cortex lesions in both breeds increase the responsiveness of tectal units to flashing spots and almost entirely remove the directional selectivity exhibited by tectal units, although units with asymmetric surrounds are still found. In normal cats, the lesions change the ocular dominance distribution, skewing it more strongly toward the contralateral eye. In Siamese cats, the ocular dominance distribution remains unchanged after a visual cortex lesion. 7. The squint commonly exhibited by Siamese cats is regarded as a compensation for the anomalous retinotectal topography. It is suggested that, in the absence of an adaptive modification, the anomalous retinotectal projection would lead to mislocalization in Siamese cats just as it does in frogs and hamsters whose retinotectal projection has been experimentally altered. The convergent strabismus which Siamese cats commonly exhibit may be a cure for the abnormal retinal projections rather than a disease.

A second neural mechanism of binocular depth discrimination

Abstract: 1. Rotation of an object about its horizontal axis, towards or away from the viewer's eyes, usually causes the images of its contours to have slightly different orientations on the two retinae. 2. We recorded action potentials from binocular neurones in the cat's visual cortex and measured their orientation-selectivity carefully in both eyes. 3. The optimal orientation for a single cell is not necessarily identical on both retinae. For a large sample of cells there is a range of more than + 15° ( S.D. about 6–9°) in the difference of preferred orientation in the two eyes. These interocular differences in receptive field properties cannot be attributed to rotation of the eyes or to the errors of measurement. 4. During simultaneous binocular stimulation the images must not only lie in the correct place on both retinae but also have exactly the right orientation for both receptive fields in order to elicit the maximum response from a neurone. 5. Therefore certain binocular cells respond specifically to objects tilted in three-dimensional space towards the cat, or away from it.

Hypercomplex cells in the cat's striate cortex.

Abstract: .here has already been some discussion concerning hierarchical versus parallel processing of information in the striate cortex and I would like to add a few comments. Hubel and Wiesel,' in their classical papers, differentiated three categories of cells in the cat's striate cortex. They further suggested a hierarchical model which would explain the organization of the receptive fields of each type of cell. Thus only simple cells would receive a direct excitatory input from lateral geniculate neurons (LGN), and a number of simple cells with a common optimal orientation and slightly offset receptive-field positions would then provide the excitatory input to the complex cells. Finally, different complex cells with a common preferred orientation but again with offset receptive-field positions would provide excitatory and inhibitory inputs to the hypercomplex cells. The inhibitory input to the hypercomplex cell would explain that the sharp reduction in the discharge, as an optimally oriented stimulus, is elongated beyond the excitatory region in the receptive field. If the Hubel and Wiesel model is correct, one would expect a basic similarity between the responses of complex and hypercomplex cells. However, on the basis of the organization of their receptive field, we have been able to differentiate four classes of cells in the cat's striate cortex: simple, complex, and two distinct classes of hypercomplex cells. The majority of hypercomplex cells (Fig. 1, Type 1) have responses very similar to those of simple cells and their receptive fields can be subdivided into

Inhibitory interaction in the cat's lateral geniculate nucleus.

Abstract: Spike activities of optic tract fibers and corresponding relay cells were recorded simultaneously in layers A and A1 of the dorsal lateral geniculate nucleus of the cat. Light stimuli of various diameters were shone into the receptive field center of these unit pairs and their input/output ratios were determined. An increase of the stimulus size leads to an impairment of the input/output ratio in on-center and off-center relay cells. This suppressive effect has approximately the same latency as the excitatory response.

Factors forming the edge of a receptive field: the presence of relatively ineffective afferent terminals.

Abstract: A specialized type of spinal cord cell has its cell body in lamina IV and has a small low threshold cutaneous receptive field which is remarkable for its abrupt edge No signs could be found of a subliminal fringe to this field since its size remains fixed during wide excursions of the cell's excitability Reversible blocking of peripheral nerves and dorsal roots showed that the afferents responsible for exciting these cells following natural stimuli, run in a restricted area of peripheral nerve and dorsal root When the fibres necessary to sustain the natural stimulus receptive field were blocked, it was shown that other large myelinated fibres in neighbouring roots were still capable of firing the cell monosynaptically following electrical stimulation of the root or periphery although no natural stimuli were able to change the cell's excitability It is necessary to divide the afferent synapses on such cells into a class which is highly effective in firing the cell on natural stimulation and a second class which has no effect yet detected following natural stimuli but which can fire the cell monosynaptically if synchronously activated by electrical stimulation Suggestions are made for possible presynaptic and post-synaptic mechanisms which might divide the effect of arriving impulses into two such classes

Movement-sensitive neurones in the toad's retina.

Abstract: 1. Neuronal classes. Recordings from single optic nerve fibers of the common toad Bufo bufo (L.) have revealed three types of retinal ganglion cells which correspond to classes II, III and IV in the frog. 2. Receptive field organization. All neurones have a central excitatory field, ERF, surrounded by an inhibitory one, IRF (Fig. 10a, b). The ERF for each cell class was ERFII ≈ 4°, ERFIII ≈ 8°, ERFIV = 12–15°. 3. Illuminance change over the entire visual field had no effect on class II neurones, produced an “on — off” response in class III and an “off” response in class IV (Fig. 2b–c). 4. Angular size of stimuli moved through the central rezeptive field (constant angular velocity and stimulus background contrast). (i) Squares: As the edge length approached the ERF diameter, the discharge rate of all neurones increased, then decreased for larger squares which activated the inhibitory surround (Figs. 3, 4a). (ii) Extending a vertical stripe in the horizontal direction of movement had a similar effect (Fig. 4b). (iii) Elongating a horizontal stripe by more than 2° in the direction of movement produced no change in the discharge rate (Fig. 4c). (iv) Simultaneous movement of two stimuli a and b through the ERF caused a greater discharge than for either allone. Responses to a in the ERF were inhibited if b was in the IRF (Fig. 5). 5. Increased angular velocity (constant contrast and angular size) produced increased activation of all neurones (Fig. 6a–d). The degree of increase was different in each neuronal class (Fig. 7A). 6. Stimulus background contrast (constant angular size and velocity). The discharge rate generally increased for increasing contrast between stimulus and background (Fig. 8). A white stimulus against black background produced maximal activation of class II neurones; black on white was maximally effective for the other two classes (Fig. 9a–c). 7. Input-output functions. A power function best describes the relationships between impulse frequency and (i) stimulus angular velocity, and (ii) stimulus background contrast (Eqs. 9, 11). Impulse frequency is logarithmically dependent on stimulus area (Eqs. 3–6). 8. Retinal output and visual behaviour. The neurophysiological findings are compared with quantitative results previously obtained from corresponding behavioural experiments concerning visually induced prey-catching and avoidance reactions.

Properties of the surround response mechanism of cat retinal ganglion cells and centre-surround interaction

Abstract: 1. The properties of the surround response mechanism of on-centre cells and its interaction with the centre mechanism were studied by recording from single optic tract fibres. In many of the experiments the spatial distribution of the light within the retinal image of the stimuli was measured. 2. Pure surround responses of on-centre cells were isolated using a centrally located steady light which selectively desensitized (adapted) the centre mechanism. This permitted a peripheral flashing stimulus whose luminance varied over a range as great as 1·38 log units to elicit surround responses which, for any given cell, were of invariant shape. The rate of decay of the firing frequency of the spike burst at ‘off’ varied from cell to cell. The general characteristics of such pure surround responses to squarewave stimuli were described. The plot of the magnitude of pure responses against stimulus luminance, at constant background conditions, was curvilinear. 3. The pure surround response of two off-centre cells was isolated; it was similar in shape to the pure centre response of on-centre cells. 4. Interaction of centre and surround mechanisms of on-centre cells was studied by eliciting a pure central and a pure surround response from the same cell. The electronically obtained algebraic sum of these two pure responses equalled the mixed response of the ganglion cell to simultaneous presentation of the stimuli which evoked the pure responses when presented singly. This is probably best explained by algebraic summation of centre and surround inputs. 5. The pure surround response from two cells to a fixed flashing stimulus was attenuated by a steady field adapting light, both when this was superimposed upon the stimulus and when not superimposed. In the latter case, (i) when the spatial separation between the flashing stimulus and the adapting light was at a minimum, less than 10% of the adapting flux fell inside the boundaries of the stimulating flux, and (ii) the response was attenuated also if the adapting light was in the geometric centre of the receptive field. These results indicate that the adaptation pool of the surround mechanism extends to the central portions of the receptive field. 6. Nearly half the cells tested did not yield pure surround responses. This was probably due to differences, within the ganglion cell population, (i) of the spatial distribution of the ratio of centre to surround signal sensitivity and (ii) of differences in the ratio of centre to surround adaptivity in the receptive field middle. It was not due to excess adaptive flux falling outside the region of maximal centre mechanism adaptivity, nor due to excess stimulus flux falling inside the region of maximal signal sensitivity.

Dogfish ganglion cell discharge resulting from extrinsic polarization of the horizontal cells.

Abstract: 1. Ganglion cell discharges were evoked by extrinsic polarization of the horizontal cells in the retina of the smooth dogfish (Mustelus canis). Depolarization of the horizontal cell gave rise to a discharge similar to that evoked by a spot of light (centre type response) and hyperpolarization of the horizontal cell, a discharge similar to that by an annulus (surround type response). 2. Procion dye injection established that the current-passing electrode was sometimes located in the external horizontal cell. Other possibilities, such as middle and internal horizontal cells, were neither confirmed nor excluded. 3. Activation of ganglion cells by current was possible under completely dark-adapted conditions and for several log units above this level. 4. Depolarizing current enhanced the ganglion cell response evoked by a light spot in the centre of its receptive field; hyperpolarizing current antagonized the response to the same flash. 5. The results are consistent with the supposition that a potential change in the horizontal cell, irrespective of its polarity, or whether produced by light or current, spreads within a laminar layer (the S-space). The effect of the potential change is to modulate the response of bipolar cells and their input into the ganglion cell.

Receptive fields of units in the visual cortex of the cat in the presence and absence of bodily tilt.

Abstract: The receptive fields of units in the visual cortex of anaesthetised cats were studied using spots or slits of light. Some fields were found to be stable when they were repeatedly plotted with the cat maintained in the horizontal position: other fields were not stable and the sharpness of spatial tuning varied though the orientation of the axis did not shift. When the cat was tilted the field axis of the majority of cells followed the tilt. In 14 cells, however, changes occurred in the receptive field which were not observed when the animal remained in the horizontal plane. These changes included drifts of the field axis in a direction which, with one exception, was opposite to the tilt, and alterations in the spatial extent of the field. On returning the animal to horizontal the axis of 4 fields drifted past the original orientation. These effects were not eliminated by either bilateral destruction of the labyrinth or high cervical transection of the spinal cord. The time of onset of the tilt effects varied from cell to cell: some of this variability is probably an effect of anaesthesia. The findings are consistent with the view that the receptive field of certain cells in the visual cortex are capable of being modified, one of the modifying influences being the orientation of the body in space.

Visual experience as a determinant of the response characteristics of cortical receptive fields in cats

Abstract: Cats reared with their visual world restricted to vertical lines for one eye and horizontal lines for the other had, in their visual cortices, units with elongated receptive fields that were either vertically or horizontally oriented. These receptive fields could be mapped only using that eye which had seen lines of the same orientation during development. Other units had diffuse, unresponsive receptive fields (Hirsch and Spinelli, 1970). Six cats, from the group above, were revived and allowed normal binocular viewing in an attempt to determine the possibility and extent of adding other types of receptive fields by giving other experiences to their visual systems. After exposure to a normal environment for up to 19 months it was found that indeed there had been a massive increase in the percentage of those classes of receptive fields that were either absent or weak at the end of the selective visual experience. Significantly, these receptive fields, acquired during binocular viewing, were very often binocular. The results, however, show that units whose response characteristics mimic the stimuli viewed during development were almost completely unaffected by normal binocular visual experience, i. e., they were monocularly activated and had the orientation appropriate for the stimuli viewed by the eye from which they could be mapped. Most impressive are a few units whose receptive field shape is almost a carbon copy of the pattern viewed during development. The data provide evidence that visual experience has a direct continuing and lasting effect on the functional connectivity of cells in the visual cortex.

The functional organization of the isthmo‐optic nucleus in the pigeon

Abstract: 1. Extracellular single unit records were taken from the isthmo-optic nucleus of the pigeon, locating the nucleus by the antidromic field potential resulting from electrical stimulation of the isthmo-optic tract. 2. Visual receptive fields were investigated for 248 units, and were classed into three types: directionally selective, directionally non-selective, and posterior minimum. They ranged from 3 to 10° in extent. 3. The topographical representation of the visual field in the nucleus was investigated by histological verification of electrode tracks, and a correlation with the receptive field sequences. Vertical descent through the nucleus resulted in an upwards progression of receptive field locations. Lateromedial passage through the nucleus resulted in a forwards progression of receptive field locations. 4. The representation of the lower visual field is greater than that of the superior visual field: that for the central parts of the inferior field is greater than that for the periphery, and the representation of the anterior inferior quadrant is greater than that of the posterior inferior quadrant.

Visual input to the pontine nuclei.

Abstract: Visual input to the pons was studied by anatomical and physiological methods. Cortical area 18 sends a dense projection to the rostral pons. Pontine cells respond best to targets moving in a preferred direction over a large receptive field, which usually includes the center of gaze. The results suggest a role for pontocerebellar pathways in visual control of movement.

The outer disinhibitory surround of the retinal ganglion cell receptive field

Abstract: 1. There is an outer disinhibitory zone surrounding the classical inhibitory surround of the retinal ganglion cell receptive field.2. The disinhibitory surround is strong and narrow in ;sustained' cells but weak and laterally spread in ;transient' cells.3. The disinhibitory surround can be demonstrated using a black spot as a probing stimulus as well as by a white spot, and is therefore not an artifact of scattered light.4. Stimulation with a light spot in the disinhibitory zone gives an increase in firing to ;stimulus on' in on-centre cells and to ;stimulus off' in off-centre cells.5. The disinhibitory surround may be revealed by plotting the latency of the first spike discharge following stimulation against position in the receptive field. The disinhibitory zone shows a decrease in latency to the centre-type stimulus.6. The disinhibitory surround may be revealed by plotting the threshold intensity of a spot against position in the receptive field. It is thus a feature of the sensitivity gradients of both ;transient' and ;sustained' cells.7. Using two spots, one at the centre of the receptive field and the other at varying distances from the receptive field centre, dynamic interactions between the centre, inhibitory and disinhibitory zones are demonstrated. A spot presented in the disinhibitory zone causes an enhancement of the centre response when flashing in phase with the centre spot, while it causes inhibition of the centre response when presented 180 degrees out of phase.8. A scheme for the anatomical basis of the disinhibitory surround is proposed, and the relation of disinhibition to the spatial transfer characteristics of the visual pathways is discussed.