Showing papers on "Receptive field published in 1973"

Properties of sustained and transient ganglion cells in the cat retina

Abstract: 1. The functional basis for a sustained/transient classification of cat retinal ganglion cells has been strengthened by quantitative measurements of the sizes of the centre and surround components of receptive fields. Transient cells had larger surrounds than sustained; the distributions were non-overlapping. Although the distributions of centre sizes overlapped, the transient cells had very significantly larger centres on average. 2. There were characteristic differences in area-threshold and annulus-threshold curves and shapes of responses to brief and long flashes of light, and relative differences in the nature of surround adaptation and maintained discharge rates. 3. The distinction of sustained from transient units survived over a wide range of backgrounds including the two principle reorganizations of function: relative weakening of surround components at low background; Purkinjě shift at high. 4. Sustained and transient units were differentially distributed in the retina: there was an overwhelming preponderance of sustained units in the area centralis. 5. It is proposed that the transient units are the so-called multidendritedeep cells and the sustained units are the variously styled small ganglion cells.

Receptive fields of simple cells in the cat striate cortex

Abstract: 1. The excitatory and inhibitory components in the receptive fields of unimodal simple cells in the striate cortex of the cat anaesthetized with nitrous oxide have been described using slits of light and single light-dark edges as stimuli. 2. There is a small excitatory region (excitatory complex) centrally located in the receptive field that is made up of various combinations and spatial arrangements of subliminal excitatory and discharge subregions or centres. 3. The subliminal excitatory centres were revealed by a binocular facilitation technique. The excitability of the cell was raised by repeated stimulation via one eye while the neurone was tested with single edges via the other eye. 4. The subliminal excitatory and discharge centres are each specifically activated by only one type of edge, light-dark or dark-light, and then only in one direction of motion. All the subregions in the excitatory complex have the same optimal stimulus orientation. 5. Inhibitory components in the receptive field were identified by stimulating the cell with bars of light and single edges against an artificial background discharge produced by repeated stimulation separately applied either to the same eye (monocular conditioning) or to the other eye (binocular conditioning). There are powerful inhibitory sidebands to either side of the excitatory complex and these inhibitory regions merge to include the excitatory complex when stimulus orientation is angled away from the optimal. 6. Excitation is highly stimulus specific whereas inhibition is non-specific. 7. The organization of the two receptive fields of a binocularly discharged cell can be closely similar. 8. The attempt is made to translate the concept of subliminal excitatory and discharge centres into specific neural mechanisms involving both the geniculo-cortical input and various intracortical circuits. 9. These new developments call for only minor modifications to the model we have proposed for the organization of the receptive field.

Receptive field organization of bipolar and amacrine cells in the goldfish retina

Abstract: 1. Intracellular recordings were made from bipolar and amacrine cells in the isolated goldfish retina. Cells were identified mainly from their response patterns to a spot and an annulus in reference to the knowledge obtained from the previous work of intracellular Procion Yellow injection. Using white light and monochromatic lights receptive field organization of recorded cells were analysed. 2. All bipolar cells had a centre-surround organization in their receptive fields. The field centre was estimated to be 100–200 μm in diameter, and the surround 1–1·5 mm. 3. Bipolar cells were classified into two types according to the response properties to monochromatic lights. Opponent colour cells received inputs from red and green cones, responding with red on-centre, red and green off-surround or vice versa. Cells without colour coding received input from red cones both in the field centre and the surround. In these cells the centre and the surround were well balanced. 4. Amacrine cells were also classified into two types, a sustained type and a transient type. The sustained type amacrine cells responded with a steady potential change and were colour coded. They were hyperpolarized by red and depolarized by green light. The transient type amacrine cells responded with transient depolarization at on and off of light flashes. They received input chiefly from red cones and were not colour coded. Both types of amacrine cells showed a large spatial summation in an area over 2·5 mm; centre-surround antagonism was not seen. 5. Comparing the size of the receptive field with anatomy, especially with the size of dendritic spread, the field centre of bipolar cells agreed in size with their dendritic spread. Bipolar cell surround clearly exceeded its dendritic field. Since the response properties of the bipolar cell surround was mimicked most closely by the receptive field of external horizontal cells, the input to the bipolar cell surround is thought to be mediated by external horizontal cells. 6. By comparing receptive field properties of various retinal cells it is suggested that both the opponent colour bipolar cells and the colour coded amacrine cells converge on to the double opponent ganglion cells.

Environmental Modification of the Visual Cortex and the Neural Basis of Learning and Memory

Abstract: IN the primary visual cortex of a normal cat the neurones are almost all orientation detectors, which respond only if an edge or bar at the appropriate angle moves across the receptive field: all orientations are equally represented1. But early experience can grossly modify the visual cortex. Blakemore and Cooper2 reared two kittens in the dark except for a few hours each day spent in cylindrical chambers painted with black and white stripes at one orientation. These two animals, which experienced almost 300 h of exposure to stripes during their first 5 months of life, had no cortical neurones responding to the orientation perpendicular to the stripes that they saw when they were young. Almost all their cortical cells preferred orientations within 45 deg of the experienced angle. The phenomenon involves active modification of the receptive fields of the neurones, and not mere degeneration of unused cells, because there were no regions of silent cortex and no histological evidence of degeneration.

The contribution of membrane hyperpolarization to adaptation and conduction block in sensory neurones of the leech.

Abstract: The factors underlying sensory adaptation and conduction block have been studied in cutaneous mechanoreceptor neurones of the leech. A touch-sensitive cell was activated by applying mechanical or electrical stimuli to its receptive field on the skin. Impulses were recorded extracellularly from its axons and intracellularly from its cell body, which is situated within the C.N.S.1. Activation of the touch cell by mechanical stimuli revealed two distinct types of adaptation with characteristically different time courses. Sustained pressure on the skin caused a brief burst of impulses at the onset of the stimulus. This rapid adaptation to pressure was restricted to the part of the receptive field that had been stimulated mechanically. A second type of adaptation developed more slowly during the course of repetitive mechanical stimulation. It persisted for many seconds after the end of a train of impulses and appeared as an increase in the threshold to mechanical stimuli not only in the region of skin that had been rubbed but throughout the receptive field of the cell.2. Impulses initiated in the cell body propagated antidromically towards the skin and also raised the threshold to touch, indicating that after-effects of impulse activity were responsible for the long-lasting threshold increase.3. Repetitive mechanical stimulation could also produce a reversible conduction block in branches of the touch cell. The block occurred in discrete regions of low safety factor such as axonal branch points both within the ganglion and in the periphery. In some experiments impulses intermittently failed to reach one axonal branch yet continued to invade a separate branch of the same cell.4. Several lines of evidence indicate that both conduction block and the slow component of adaptation are linked to a prolonged hyperpolarization that follows repetitive stimulation of the touch cell. Strophanthidin, which blocks the after-hyperpolarization in touch cells, reduced the adaptation following trains of impulses and also relieved a conduction block previously established by repetitive stimulation. Furthermore, a comparison of the effects of hyperpolarizations produced by current injection and by repetitive firing showed that most of the threshold increase in the cell body after a train of impulses could be attributed directly to the membrane hyperpolarization.5. These experiments suggest several ways in which repetitive activity can have pronounced and long-lasting effects on the performance of a highly branched sensory cell. Thus a relatively small number of impulses in a touch cell can markedly decrease its sensitivity to touch. The functional role of the conduction block observed during vigorous stimulation is not as clear because activity for many seconds or minutes is usually needed to establish a block in the larger branches of the cell.

The visual areas in the splenial sulcus of the cat.

Abstract: 1. The extreme periphery of the visual field is represented in the upper wall of the splenial sulcus where the sulcus is horizontal, and in its anterior wall more posteriorly where the sulcus runs downwards and laterally. About half the cells whose fields lie between 50 and 90 degrees from the area centralis have a sharply horizontal preferred orientation.2. Beyond the lateral edge of visual I there is a narrow band of visual cortex in which the receptive fields return towards the area centralis as one moves 1-1.5 mm laterally. Their receptive fields are usually about 20-30 degrees degrees across, but all orientations are found. The more central fields may be binocular and those at the area centralis may be as small as 1 degrees in diameter.3. This band has been called the splenial visual area. It does not seem to have properties corresponding to those of visual II nor of visual III.

Receptive field analysis: responses to moving visual contours by single lateral geniculate neurones in the cat

Abstract: 1. Responses of single geniculate cells to moving light and dark bars and light/dark edges were studied in cats anaesthetized with nitrous oxide/oxygen (70%/30%).2. Over 95% (230 out of 241) of geniculate cells had antagonistic centre-surround receptive fields. Their responses could be characterized as centre-activated or centre-suppressed depending on the receptive field type (ON- or OFF-centre) and the contrast between stimulus and the background (brighter or darker than the background). Moving light and dark edges evoked responses which were very similar to the responses evoked by these stimuli in simple cells of striate cortex.3. A number of cells (45) with antagonistic centre-surround receptive fields were classified according to their X/Y (sustained/transient) properties. Units with sustained properties (X-cells) did not increase their firing rate with an increase of stimulus velocity and some of them showed a clear-cut preference for slow movement (around 1-2 degrees /sec). On the other hand, units with transient properties (Y-cells) showed a clear-cut preference for fast-moving stimuli (50-100 degrees /sec.)4. Elongation of the stimulus beyond the antagonistic surround in both X- and Y-cells produced a clear-cut reduction of amplitude of both centre and surround components of the response. Thus the existence of a suppressive field component beyond the antagonistic surround is confirmed.5. About 5% of cells had receptive fields which did not have an antagonistic centre-surround organization but gave a mixed ON-OFF discharge from the central region of the field. Around the central region there was a silent suppressive zone. These units were not directionally selective, responded preferentially to fast-moving stimuli (25-100 degrees /sec) and had a substantial (spontaneous) maintained activity.

Organization of on-off cells in the retina of the turtle

Abstract: 1. The organization of central and peripheral responses for one type of spike-producing cell in the retina of the turtle (Pseudemys scripta elegans) has been studied. These cells produced a short burst of spikes following the onset and offset of a small spot of illumination (i.e. ON—OFF cells). The effect of increasing the area of illumination was to include a peripheral inhibition. Intracellular ON and OFF responses were, however, affected differently. 2. ON—OFF cells marked intracellularly with Procion Yellow M4R had somata in the inner nuclear and ganglion cell layers. 3. Peripheral inhibition could be evoked without a change in the membrane potential of horizontal cells. 4. Passing 5 nA hyperpolarizing or depolarizing current through a micropipette within a horizontal cell elicited in ON—OFF cells a transient excitation following the onset and offset of current. 5. It is concluded that inhibition from the periphery of an ON—OFF cell receptive field is not mediated by luminosity horizontal cells but more probably by peripheral bipolar cells.

Electrophysiological analysis of interhemispheric relations in the second somatosensory cortex of the cat.

Abstract: 1. Evoked potential studies done on chloralose anesthetized cats showed that potentials elicited by stimulation of the ipsilateral body surface and recorded in the second somatosensory cortex (SII) are mediated largely by contralateral somatosensory cortex by way of the corpus callosum; the ipsilateral posterior complex of the thalamus mediates only a small part of these potentials. Under the depressed conditions of barbiturate anesthesia only the ipsilateral posterior complex mediates these potentials. 2. Cells in anterior SII of unanesthetized, painlessly immobilized cats respond not only to light cutaneous stimulation but also to stimulation of contralateral somatosensory cortex. For some SII neurons stimulation of contralateral SII can inhibit discharges elicited by stimulation of the contralateral cutaneous receptive field. 3. All neurons excited by stimulation of contralateral SI and/or SII had bilateral receptive fields. These and other data suggest that much of the activity evoked by stimulation of the ipsilateral portion of a bilateral receptive field is mediated by contralateral somatosensory cortex by way of the corpus callosum. 4. Some neurons in SII which have small receptive fields on the contralateral forepaw can be discharged antidromically by stimulation of contralateral SII. Additional data show that large, slow wave potentials evoked by stimulation of the ipsilateral forepaw are mediated by the corpus callosum. Thus, contrary to expectations from anatomical studies, distal as well as proximal structures are represented in the topographical organization of the corpus callosum.

Properties of excitatory and inhibitory regions in the receptive fields of single units in the cat's superior colliculus.

Abstract: 1. The receptive field properties of single units in the cat superior colliculus have been analyzed quantitatively from average response histograms of the activity elicited in these units by moving light slits. 2. The majority of receptive fields, when tested with narrow (less than 0.5° wide) moving stimuli, have a single excitatory region. In the minority of the receptive fields, two or more spatially separated excitatory regions could be differentiated. Each excitatory region usually had an elliptical or rectangular shape with its major axis parallel or nearly parallel to the horizontal meridian of the visual field. A small proportion (1%) of the receptive fields had only inhibitory regions. 3. A majority of collicular units showed preferences for a particular speed of stimulus motion. Cells with preferences for slow ( 100°/sec). There was also a positive correlation between the speed preference of a unit and the size of the excitatory region of its receptive field. 4. A high proportion of cells had little (<1 spike/sec) spontaneous activity. Of units with high spontaneous activity, a majority had large excitatory regions in their receptive fields and did not show direction selectivity. 5. In addition to the excitatory regions in most receptive fields, there were also inhibitory regions. Stimulation of the latter suppressed both the excitatory response and background firing of the cell. The inhibition and excitation had the same latency, but inhibition lasted at least 150 msec after discontinuation of stimulation, thus reducing responsiveness of the cell after the stimulation. 6. It was found that the majority of collicular units possess a preference for stimulus movements away from the area centralis. 7. Evidence is presented supporting the view that direction selectivity in collicular units is principally determined by unidirectional inhibition. 8. Implications of these results for the mechanism determining receptive field organization in the colliculus are discussed.

Contrasts in spatial organization of receptive fields at geniculate and retinal levels: centre, surround and outer surround.

Abstract: 1. The organization of receptive fields of retinal ganglion cells and A-laminae cells from the dorsal lateral geniculate nucleus (LGN) of the cat are compared under identical conditions. Some aspects of the geniculate data have been given elsewhere (Hammond, 1972b). 2. The receptive fields of geniculate cells consist of three zones — centre, antagonistic surround and synergistic outer surround — compared with only two for retinal cells. This result further supports the theory that the centre and surround of geniculate cell receptive fields derive from convergent, but discrete, retinal inputs. 3. The surrounds of geniculate receptive fields are known to be more powerfully antagonistic on their centres than is true of retinal cells. This relationship is re-examined. 4. Unlike geniculate fields, the locus of maximum sensitivity for the receptive field surround of retinal cells is not invariant either to stimulus geometry or adaptational state. 5. The latter result strongly suggests that the surround mechanism for retinal cells extends through the centre of the field. It establishes unequivocally that the overlap between receptive field centre and surround mechanisms, only marginal in geniculate, is very extensive indeed in retina.

The nucleus basalis of the pigeon: a single-unit analysis.

Abstract: Single unit responses were recorded from neurons in the nucleus basalis of the pigeon. Two hundred and twelve basalis cells, from 23 birds, were characterized in terms of modality, receptive area and adaptive properties. Most basalis units (97%) fired spontaneously in bursts of a few spikes separated by one to two seconds of silence. All units were activated by light mechanical stimulation of the beak or buccal cavity. The units adapted rapidly to a maintained stimulus, but fired vigorously when the stimulating probe moved back and forth across the surface of the receptive area. Receptive fields fell into two clearly separable groups with respect to size: small fields, less than 15 mm2, generally clustered near the beak tips, and large fields occupying from one-third to the entire beak surface. Both unilateral (ipsilateral or contralateral) and bilateral receptive areas were encountered. Nucleus basalis units could be driven electrically by stimulation of the beak surface or the main sensory trigeminal nucleus (PrV). The data suggest that n. basalis cells are particularly responsive to movement of food (grains) within the mouth and that this information is relayed by trigeminal afferents to the PrV, thence to the n. basalis via a partially decussating quinto-rontal tract. The results are discussed in relation to the role of the n. basalis in the control of feeding behavior in the pigeon.

Binocular Neurones which signal Change of Disparity in Area 18 of Cat Visual Cortex

Abstract: BINOCULARLY activated neurones which seem to play a specific role in the detection of retinal image disparity have been described for both cat and monkey visual cortex1–6. The receptive field properties are such that for a given position of the eyes, each neurone will respond to an optimally oriented, moving line only if there is a particular disparity between the images of that line on each retina. As most of the receptive field disparities have a horizontal component, the response is related to movement of the line in a plane at a particular distance. If the plane of the optimally oriented stimulus is moved so it is effectively closer or further from the animal, there is a sharp decrease in the binocular response of the neurone, often to levels below the response to one eye alone4,5. Most of the disparity-specific neurones so far described1–6 are maximally responsive when the disparity is constant, at some particuar value, and cease to respond well when the disparity is changed from that value.

Neuronal Physiology of the Visual Cortex

Abstract: The behaviour of higher mammals and humans in the spatial environment is to a large extent visually guided, and requires form vision and fine discrimination between similar patterns and symbols. This ability seems related to the specificity and complexity of stimuli needed for activation of single neurones of the visual cortex, in contrast to the relatively unselective requirements of retinal and lateral geniculate neurones. The retina and tectum of some lower vertebrates including frogs, pigeons and rabbits, already possess selective cells responding to very specific aspects of stimulation. The class differences are in part connected with the chiasmatic decussation and mechanisms of binocular and stereoptic vision which are prominent in the visual cortex of animals with forward looking rather than laterally placed eyes. They are also associated with the enormously expanded behavioural repertoire of, for instance, primates in comparision to lower vertebrate forms. The complex primate cortex permits a rich interaction and modification of cellular performance according to the momentary needs and disposition of the individual. The opportunities which allow plasticity of performance also unfortunately often lead to response unpredictability, despite careful laboratory controls.