Topic
Receptive field
About: Receptive field is a research topic. Over the lifetime, 8537 publications have been published within this topic receiving 596428 citations.
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TL;DR: Using functional magnetic resonance imaging (fMRI) and cortical unfolding techniques, the retinotopy, motion sensitivity, and functional organization of human area V3A was analyzed and the situation is qualitatively reversed: V3 is reported to be prominently motion-selective, whereas V 3A is less so.
Abstract: Using functional magnetic resonance imaging (fMRI) and cortical unfolding techniques, we analyzed the retinotopy, motion sensitivity, and functional organization of human area V3A. These data were compared with data from additional human cortical visual areas, including V1, V2, V3/VP, V4v, and MT (V5). Human V3A has a retinotopy that is similar to that reported previously in macaque: (1) it has a distinctive, continuous map of the contralateral hemifield immediately anterior to area V3, including a unique retinotopic representation of the upper visual field in superior occipital cortex; (2) in some cases the V3A foveal representation is displaced from and superior to the confluent foveal representations of V1, V2, V3, and VP; and (3) inferred receptive fields are significantly larger in human V3A, compared with those in more posterior areas such as V1. However, in other aspects human V3A appears quite different from its macaque counterpart: human V3A is relatively motion-selective, whereas human V3 is less so. In macaque, the situation is qualitatively reversed: V3 is reported to be prominently motion-selective, whereas V3A is less so. As in human and macaque MT, the contrast sensitivity appears quite high in human areas V3 and V3A.
814 citations
TL;DR: Intracellular recordings have been made of the responses to light of single cones in the retina of the turtle and the shape of the hyperpolarizing response to a flash depends on the pattern of retinal illumination as well as the stimulus intensity.
Abstract: 1. Intracellular recordings have been made of the responses to light of single cones in the retina of the turtle. The shape of the hyperpolarizing response to a flash depends on the pattern of retinal illumination as well as the stimulus intensity.
2. Although changes in the stimulus pattern can produce changes in the effective stimulus intensity, the responses to certain patterns cannot be matched by any adjustment of stimulus intensity.
3. The initial portion of responses to large or small stimulating spots is proportional to light intensity; this allows comparison of responses when the amount of light on a cone is kept constant but the light on surrounding cones is changed. For equal light intensity on the cone, the response to a spot 2 or 4 μ in radius is smaller than that to a spot 70 μ in radius.
4. Responses to spots 70 and 600 μ in radius coincide over their rising phases and peaks without any adjustment of stimulus intensity. The responses to the larger spot, however, contain a delayed depolarization not present with the smaller spot.
5. During steady illumination of a cone with a small central spot, the response to transient illumination superimposed on the same area is greatly reduced. Illumination of cones in the near surround, however, produces a hyperpolarizing response, and illumination of cones in the more distant surround generates a delayed depolarization.
6. The results described above suggested that synaptic signals might impinge on cones. This possibility was tested by electrically polarizing one retinal cell while recording from another.
7. Currents passed through a cone within 40 μ of another cone can change the membrane potential of the latter. Not all cones within this distance show the interaction, however, and it has never been detected at distances greater than 50 μ.
8. Hyperpolarization of a horizontal cell with applied current can produce a depolarization of a cone in the vicinity. During this depolarization, the response of the cone to a flash is reduced in size and altered in shape.
9. It is concluded that the response of a cone to light may be modified by synaptic mechanisms which are activated by peripheral illumination.
805 citations
TL;DR: It is found that monosynaptic horizontal connections within area V1 are of an appropriate spatial scale to mediate interactions within the SF of V1 neurons and to underlie contrast-dependent changes in SF size, which could represent an anatomical substrate for contextual modulation and global-to-local integration of visual signals.
Abstract: Contrast-dependent changes in spatial summation and contextual modulation of primary visual cortex (V1) neuron responses to stimulation of their receptive field reveal long-distance integration of visual signals within V1, well beyond the classical receptive field (cRF) of single neurons. To identify the cortical circuits mediating these long-distance computations, we have used a combination of anatomical and physiological recording methods to determine the spatial scale and retinotopic logic of intra-areal V1 horizontal connections and inter-areal feedback connections to V1. We have then compared the spatial scales of these connectional systems to the spatial dimensions of the cRF, spatial summation field (SF), and modulatory surround field of macaque V1 neurons. We find that monosynaptic horizontal connections within area V1 are of an appropriate spatial scale to mediate interactions within the SF of V1 neurons and to underlie contrast-dependent changes in SF size. Contrary to common beliefs, these connections cannot fully account for the dimensions of the surround field. The spatial scale of feedback circuits from extrastriate cortex to V1 is, instead, commensurate with the full spatial range of center-surround interactions. Thus these connections could represent an anatomical substrate for contextual modulation and global-to-local integration of visual signals. Feedback projections connect corresponding and equal-sized regions of the visual field in striate and extrastriate cortices and cover anisotropic parts of visual space, unlike V1 horizontal connections that are isotropic in the macaque. V1 isotropic connectivity demonstrates that anisotropic horizontal connections are not necessary to generate orientation selectivity. Anisotropic feedback connections may play a role in contour completion.
801 citations
TL;DR: A receptive field model based on the ratio of signals from Gaussian-shaped center and surround mechanisms is developed that offers a parsimonious explanation of a variety of phenomena involving changes in apparent receptive field size and accounts for these phenomena purely in terms of two receptive field mechanisms that do not themselves change in size.
Abstract: Information is integrated across the visual field to transform local features into a global percept. We now know that V1 neurons provide more spatial integration than originally thought due to the ...
799 citations
TL;DR: Adult owl monkeys were trained to detect differences in the frequency of a tactile flutter-vibration stimulus above a 20-Hz standard and the cortical representations of the trained hands were substantially more complex in topographic detail than the representations of unstimulated hands or of passively stimulated control hands.
Abstract: 1. Adult owl monkeys were trained to detect differences in the frequency of a tactile flutter-vibration stimulus above a 20-Hz standard. All stimuli were delivered to a constant skin site restricted to a small part of a segment of one finger. The frequency-difference discrimination performance of all but one of these monkeys improved progressively with training. 2. The distributed responses of cortical neurons ("maps") of the hand surfaces were defined in detail in somatosensory cortical area 3b. Representations of trained hands were compared with those of the opposite, untrained hand, and to the area 3b representations of hands in a second set of monkeys that were stimulated tactually in the same manner while these monkeys were attending to auditory stimuli (passive stimulation controls). 3. The cortical representations of the trained hands were substantially more complex in topographic detail than the representations of unstimulated hands or of passively stimulated control hands. 4. In all well-trained monkeys the representations of the restricted skin location trained in the behavioral task were significantly (1.5 to greater than 3 times) greater in area than were the representations of equivalent skin locations on control digits. However, the overall extents of the representations of behaviorally stimulated fingers were not larger than those of control fingers in the same hemisphere, or in opposite hemisphere controls. 5. The receptive fields representing the trained skin were significantly larger than receptive fields representing control digits in all but one trained monkey. The largest receptive fields were centered in the zone of representation of the behaviorally engaged skin, but they were not limited to it. Large receptive fields were recorded in a 1- to 2-mm-wide zone in the area 3b maps of trained hands. 6. Receptive-field sizes were also statistically significantly larger on at least one adjacent, untrained digit when compared with the receptive fields recorded on the homologous digit of the opposite hand. 7. There was an increase in the percent overlaps of receptive fields in the cortical zone of representation of the trained skin. A significant number of receptive fields were centered on the behaviorally trained skin site. 8. The effects of increased topographic complexity, increased representation of the trained skin location, increased receptive-field size, and increased receptive-field overlap were not observed in the representations of the untrained hands in these same monkeys. Only modest increases in topographic complexity were recorded in the representations of passively stimulated hands, and no effects on receptive-field size or overlap were noted.(ABSTRACT TRUNCATED AT 400 WORDS)
791 citations