Showing papers on "Receptive field published in 1969"

Visual receptive fields of striate cortex neurons in awake monkeys.

Abstract: THE EXPERIMENTS of Lettvin and colleagues (25) and Hubel and Wiesel (19) have indicated that a neuron in the vertebrate visual system is sensitive to particular characteristics of the visual stimulus. These characteristics have been referred to as the “trigger features” of the stimulus (3) and include such factors as size, shape, orientation, color, and rate and direction of movement; the area of the visual field over which the stimulus is effective is referred to as the receptive field of the neuron (17). Receptive-field characteristics of visual system neurons have subsequently been determined in a wide range of animals (for references see 7, 16). In addition, Hubel and Wiesel (19-24, 30) have shown that there are changes in the characteristics of the stimulus needed to activate a neuron at successively higher levels of the visual system. In both cats and monkeys they observed a progressive change in the predominant type of receptive field from the circular receptive fields of retinal ganglion and lateral geniculate cells, through the elongated receptive fields of the simplest cortical cells, to the more complex fields of other cortical neurons. This understanding of the visual system has been derived entirely from experiments in which the animal was paralyzed and frequently also anesthetized. Such procedures have been designed to eliminate all eye movements, particularly the small eye movements of physiological nystagmus that are characteristic of normal vision (1). The purpose of the present experiments was to determine whether receptive fields of striate cortex neurons in the awake, behaving animal are similar to those in the anesthetized,

Visual Receptive Fields of Neurons in Inferotemporal Cortex of the Monkey

Abstract: Neurons in inferotemporal cortex (area TE) of the monkey had visual receptive fields which were very large (greater than 10 by 10 degrees) and almost always included the fovea. Some extended well into both halves of the visual field, while others were confined to the ipsilateral or contralateral side. These neurons were differentially sensitive to several of the following dimensions of the stimulus: size and shape, color, orientation, and direction of movement.

Inhibitory and excitatory factors influencing the receptive fields of lamina 5 spinal cord cells.

Abstract: Examination of cutaneous receptive fields (RFs) of lamina 5 cells in the lumbar spinal cord of decerebrate cats shows them to have three distinct zones with respect to mechanical and electrical stimulation. The mean response rate to both mechanical and electrical stimulation in zone 1 increases steadily up to the highest strengths used; in zone 2, surrounding zone 1 mainly proximally, mild stimuli reduce the mean rate, stronger stimuli increase it; in zone 3, mainly proximal to zone 2, all stimuli reduce the rate.

Visual area of the lateral suprasylvian gyrus (Clare-Bishop area) of the cat.

Abstract: On anatomical and physiological grounds a zone of cat cortex deep in the medial bank of the suprasylvian sulcus (the Clare—Bishop area) is known to receive strong visual projections both from the lateral geniculate body and area 17. We have mapped receptive fields of single cells in this area in eight cats. Active responses to visual stimuli were found over most of the medial bank of the suprasylvian sulcus extending to the depths and over to the lowest part of the lateral bank. The area is clearly topographically arranged. The first responsive cells, recorded over the lateral convexity and 2-3 mm down the medial bank, had receptive fields in the far periphery of the contralateral visual fields. The receptive fields tended to be large, but showed considerable variation in size and scatter in their positions. As the electrode advanced down the bank, fields of successively recorded cells gradually tended to move inwards, so that in the depths of the sulcus the inner borders of many of the fields reached the vertical mid line. Here the fields were smaller, though they still varied very much in size. Receptive fields were larger than in 17, 18, or 19, but otherwise were not obviously different from the complex and lower-order hypercomplex fields in those areas. No simple fields, or concentric fields of the retino-geniculate type, were seen. Cells with common receptive-field orientation were grouped together, but whether or not the grouping occurs in columns was not established. Most cells were driven independently by the two eyes. Fields in the two eyes seemed to be identical in organization. Cells dominated by the contralateral eye were much more common than ipsilaterally dominated ones, but when cells with parafoveal and peripheral fields were considered separately, the asymmetry was seen to apply mainly to cells with peripheral fields.

Chemical and electrical synaptic connexions between cutaneous mechanoreceptor neurones in the central nervous system of the leech

Abstract: Experiments have been made to study the synaptic connexions between sensory cells in the C.N.S. of the leech. Each segmental ganglion contains six neurones that respond specifically to light touch applied to the skin; each of these `touch cells' innervates a discrete area on the surface of the body and has a characteristic set of properties by which it can be recognized. Using intracellular electrodes it has been shown that these sensory cells interact with one another through chemical and electrical synapses by way of a stereotyped set of pathways. 1. Action potentials occurring in one touch cell gave rise to synaptic potentials in the five other touch cells in the same ganglion and also in the three ipsilateral touch cells in the adjacent ganglia. Thus, synaptic interactions took place between sensory cells whose receptive fields lay within the same segment and on the same side of adjacent segments. 2. The post-synaptic potentials consisted of a short-latency coupling potential, followed by an excitatory potential and a number of inhibitory potentials. These delayed synaptic potentials occurred inconsistently and with a variable latency; they could also be recorded in the cell which had been stimulated. All of the touch cells appeared to be equally effective in initiating synaptic potentials. 3. The short-latency coupling potential was shown to be mediated through an electrical synapse by observing a voltage change in one touch cell when current was injected into its neighbour. It was not abolished by high concentrations of Mg in the bathing fluid, which blocked chemical synapses in this ganglion. This electrical synapse displayed remarkable rectification; a depolarization could spread from cell to cell in both directions, while a hyperpolarization could spread in neither. 4. The inhibitory potentials were reversed by injecting Cl into the cell. In Cl-free Ringer solution this effect was so marked that the reversed IPSPs caused long trains of impulses in touch cells, which tended to excite each other by a process of positive feed-back. 5. Synaptic potentials evoked by activation of a touch cell did not usually reach threshold since excitation and inhibition tended to cancel. The connexions between touch cells that mediated the delayed excitatory and inhibitory potentials are polysynaptic; the interneurones have not yet been found but some of their connexions could be inferred from electrical recordings. 6. Action potentials in sensory cells of a different modality (responding to pressure) also initiated synaptic potentials in the same family of touch cells. 7. The possible significance for integration of these synaptic interactions between sensory cells is discussed.

Binocular depth discrimination and the nasotemporal division.

Abstract: 1. If classical partial decussation exactly segregates the projections of right and left hemi-retinae on to the two optic tracts, the images of an object in central vision, nearer or further than the fixation point, should project to separate hemispheres. This would prevent the encoding of retinal disparity by binocularly driven neurones of the visual cortex.2. It is proposed that there is a central vertical strip of retina in each eye which is represented in both hemispheres. The angular width of this strip should be exactly one half the actual range of horizontal disparities of binocular receptive fields near the central vertical meridian.3. By recording from single neurones in the area 17/18 region in both hemispheres of a cat, it was found that there is such a strip of bilateral projection. The centres of receptive fields for units from the two hemispheres overlap in the middle of the visual field by about 1.5 degrees and the S.D. of the distribution is about 0.5 degrees .4. The horizontal disparities of the centres of binocular receptive fields were measured for samples of units representing different parts of the visual field. The range of horizontal disparity for fields near the area centralis is about 2.3 degrees , the S.D. of the distribution about 0.9 degrees . The proposed relationship between bilateral projection and disparity coding is thus confirmed.5. The origin of the bilateral projection is a matter of speculation, but in the cat some of it is almost certainly due to imprecision in the nature of the nasotemporal division of optic nerve fibres at the optic chiasma. A case can be made, however, that the overlap is partly due to connexions through the corpus callosum between the two occipital lobes.6. Evidence for the importance of the callosal pathway in man is drawn from the effects on stereopsis of section of the chiasma and the callosum.

Cat colour vision: one cone process or several?

Abstract: 1. Peripheral mechanisms that might contribute to colour vision in the cat have been investigated by recording from single units in the lateral geniculate and optic tract. Evidence is presented that the input to these cells comes from a single class of cones with a single spectral sensitivity. 2. In cats with pupils dilated a background level of 10-30 cd/m2 was sufficient to saturate the rod system for all units. When the rods were saturated, the spectral sensitivity of all units peaked at 556 nm; this was true both for centre and periphery of the receptive field. The spectral sensitivity curve was slightly narrower than the Dartnall nomogram. It could not be shifted by chromatic adaptation with red, green, blue or yellow backgrounds. 3. In the mesopic range (0·1-10 cd/m2), the threshold could be predicted in terms of two mechanisms, a cone mechanism with spectral sensitivity peaking at 556 nm, and a rod mechanism with spectral sensitivity at 500 nm. The mechanisms were separated and their increment threshold curves measured by testing with one colour against a background of another colour. All units had input from both rods and cones. The changeover from rods to cones occurred at the same level of adaptation in both centre and periphery of the receptive field. Threshold for the cones was between 0·04 and 0·25 cd/m2 with the pupil dilated, for a spot covering the centre of the receptive field. 4. None of the results was found to vary between lateral geniculate and optic tract, with layer in the lateral geniculate, or with distance from area centralis in the visual field. 5. The lack of evidence for more than one cone type suggests that colour discrimination in the cat may be a phenomenon of mesopic vision, based on differences in spectral sensitivity of the rods and a single class of cones.

Modifications of receptive fields of cells in the visual cortex occurring spontaneously and associated with bodily tilt.

Abstract: THE spontaneous activity of many cells in the visual cortex of the cat is influenced by electrical stimulation of the labyrinth and by caloric stimulation1–3. The functional significance of this vestibular input to the visual pathways is not known. We present here a preliminary account of observations which might provide a role for this input.

Multiple projection of the visual field to the medial portion of the dorsal lateral geniculate nucleus and the adjacent nuclei of the thalamus of the cat

Abstract: The organization in the cat of the projection of the visual field onto the medial part of the central half of dorsal lateral geniculate nucleus (LGNd), the medial interlaminar nucleus (MIN) and the posterior nucleus of the thalamus (PN) has been studied by systematically plotting the receptive fields of single units isolated in the nuclei by tungsten microelectrodes. Using a grid of verticals (azimuth) and horizontals (elevation), projection maps were prepared by locating the recording sites of the units in serial histological sections. We have plotted three separate but related topographical projections of the visual field, one in each nucleus. Particular attention was paid to the projection of the visual axis in the LGNd. With the possible exception of the upper periphery, the whole of the visual field is represented in the MIN, the topographical organization with respect to azimuths being the mirror-image of that in the LGNd. There were very few binocularly activated units in the MIN and no evidence was found of a laminar segregation of crossed and uncrossed optic tract terminals. The topographical projection onto the PN resembled that in the MIN except that the upper visual field was even more restricted and the organization of azimuth values was again reversed such that the central visual field projected inferomedially and the peripheral field dorsolaterally. In all three nuclei a naso-temporal overlap was found with receptive fields located across the midline in the ipsilateral hemifield for about 2° in the case of LGNd units and 6° or more in the case of the MIN and PN. Some observations are made on visually active units in the lateral posterior nucleus of the thalamus and the pulvinar, many responding binocularly.

Visual Receptive Fields of Cells in a Cortical Area remote from the Striate Cortex in the Cat

Abstract: SEVERAL workers1–4 have reported that responses evoked either by light flash or by shock applied to the optic nerve can be recorded from a region of the suprasylvian gyrus (SSG) of the cat. These responses are similar in latency and waveform to those evoked from the primary visual area. Recent studies using the Nauta method have shown that degeneration appears in the medial wall of the suprasylvian sulcus after lesions in various parts of the visual pathway, including the lateral geniculate nucleus (LGN) (ref. 5), striate and peristriate cortex6,7. The band of degeneration is separated from visual area III by a degeneration-free zone along the apex of the suprasylvian gyrus. The experiments reported here were designed to analyse the specificity of response to visual stimuli of single neurones in the medial wall of the suprasylvian sulcus.

Effect on the Superior Colliculus of Cortical Removal in Visually Deprived Cats

Abstract: ONE of the principal goals of analyses of the processing of sensory information has been an understanding of the receptive field properties of central neurones in terms of the convergence of afferents from more peripheral levels. Although it is well known that most cell groups receiving peripheral input also receive inputs descending from higher centres, there have been relatively few studies of descending effects on the organization of the receptive field1. We are concerned here with the superficial layers of the superior colliculus which receive optic nerve fibres, chiefly from the contralateral retina, and descending input from the ipsilateral visual cortex2. Most collicular cells in the normal cat are binocularly driven by slits, bars or edges and are directiorially selective, that is they respond much better to movement of a visual stimulus in one direction than to movement in the opposite direction3. After the visual cortex is removed, collicular cells respond to the same types of visual stimuli, but most cells are driven only by the contralateral eye. The cells also lose their directional selectivity and respond equally well to all directions of stimulus movement4. It therefore seems clear that some features of collicular cells depend on the cortex. The work described here with visually deprived animals demonstrates in another way the influence of the cortex on collicular cells.

Identification of cortical cells projecting to the dorsal column nuclei of the cat.

Abstract: Neurones projecting from cerebral cortex to dorsal column nuclei in the cat were identified by stimulating their axons in these nuclei and recording antidromic responses of individual cell-bodies in the cortex. Latencies of response for 42 such neurones gave conduction velocities between about 3 and 20 m./sec. Corticogracile neurones were found medially and corticocuneate neurones laterally in the sensorimotor region; and histological identification of recording sites for 24 cells showed that most lay in area 3a. Hair-sensitive skin receptive fields were found for 2 cells, and less well-defined skin excitation for 5 others: the skin area corresponded to the region served by the nucleus to which the individual cell projected. Ten corticonuclear cells tested were shown to be independent of the corticospinal tract.

[Influence of arousal on the size of the visual receptive fields of suprageniculate and geniculate neurons in the intact alert cat and in the "cerveau isole" cat].

Abstract: In alert cat, geniculate cells respond more strongly to visual stimulus when preceeded by somatic stimulation. Moreover, the somatic stimulation can enlarge the visual receptive field of these neurons which then even discharge when the light stimulus is applied outside and near to the border of the field as previously determined without any somatic stimulation.