scholarly journals Visual Spatial Summation in Macaque Geniculocortical Afferents

2006 ◽  
Vol 96 (6) ◽  
pp. 3474-3484 ◽  
Author(s):  
Michael P. Sceniak ◽  
Soumya Chatterjee ◽  
Edward M. Callaway
Keyword(s):  
Spatial Summation ◽  
Afferent Input ◽  
Visual Signals ◽  
Spatial Extent ◽  
Visual Response ◽  
Surround Suppression ◽  
Spatial Spread ◽  
Cortical Input ◽  
Visual Spatial ◽  
Spread Of Excitation

The spatial summation properties of visual signals were analyzed for geniculocortical afferents in the primary visual cortex (V1) of anesthetized paralyzed macaque monkeys. Afferent input responses were recorded extracellularly during cortical inactivation through superfusion of the cortex with muscimol, allowing investigation of lateral geniculate nucleus of the thalamus (LGN) cell properties in the absence of cortical feedback. Responses from afferent inputs were classified as magno-, parvo-, or koniocellular based on anatomical organization within the cortex, established through histological reconstructions, and visual response wavelength sensitivity. More than 80% of afferents showed strong surround suppression [suppression index (SI) >0.5] and 14% showed negligible surround suppression (SI < 0.2). Afferent responses with weak and strong surround suppression were found throughout cortical input layers 4C and 4A. High-contrast estimates of the spatial extent of the classical surround were similar to the nonclassical surround. The classical and nonclassical surrounds were, on average, 1.5-fold larger than the excitatory center. Unlike neurons within V1, the spatial extent of excitatory summation for geniculocortical afferents was contrast invariant. Nonclassical surround suppression showed slight contrast dependency with estimates larger (20%) at lower contrasts and stronger at higher contrasts (13%). Surround suppression is inherent in cortical input responses and likely derives from lateral inhibition in either the LGN or retina. Although surround suppression within afferent responses increases slightly with contrast, the spatial spread of excitation remains fixed with contrast. This argues for distinct mechanisms of action for contrast-dependent modulation in cortical and subcortical responses.

scholarly journals Visual Spatial Characterization of Macaque V1 Neurons

2001 ◽  
Vol 85 (5) ◽  
pp. 1873-1887 ◽  
Author(s):  
Michael P. Sceniak ◽  
Michael J. Hawken ◽  
Robert Shapley
Keyword(s):  
Spatial Organization ◽  
Spatial Summation ◽  
Surround Suppression ◽  
Visual Responses ◽  
V1 Neurons ◽  
Spatial Characterization ◽  
Difference Of Gaussians ◽  
Visual Spatial ◽  
Dog Model

This study characterizes the spatial organization of excitation and inhibition that influences the visual responses of neurons in macaque monkey's primary visual cortex (V1). To understand the spatial extent of excitatory and inhibitory influences on V1 neurons, we performed area-summation experiments with suprathreshold contrast stimulation. The extent of spatial summation and the magnitude of surround suppression were estimated quantitatively by analyzing the spatial summation experiments with a difference of Gaussians (DOG) model. The average extent of spatial summation is approximately the same across layers except for layer 6 cells, which tend to sum more extensively than cells in the other layers. On average, the extent of length and width summation is approximately equal. Across the population, surround suppression is greatest in layer 4B and weakest in layer 6. Estimates of summation and suppression are compared for the DOG (subtractive) model and a normalization (divisive) model. The two models yield quantitatively similar estimates of the extent of excitation and inhibition. However, the normalization (divisive) model predicts weaker surround strength than the DOG model.

Covert orienting of attention in macaques. II. Contributions of parietal cortex

1995 ◽  
Vol 74 (2) ◽  
pp. 698-712 ◽  
Author(s):  
D. L. Robinson ◽  
E. M. Bowman ◽  
C. Kertzman
Keyword(s):  
Reaction Time ◽  
Receptive Field ◽  
Parietal Cortex ◽  
Visual Cues ◽  
Reaction Time Task ◽  
Visual Response ◽  
Attention Task ◽  
Time Task ◽  
Visual Spatial ◽  
Visual Targets

1. To understand some of the contributions of parietal cortex to the dynamics of visual spatial attention, we recorded from cortical cells of monkeys performing attentional tasks. We studied 484 neurons in the intraparietal sulcus and adjacent gyral tissue of two monkeys. We measured phasic responses to peripheral visual stimuli while the monkeys attended toward or away from the stimuli or when attention was not controlled. Neurons were tested while the monkeys gazed at a spot of light (simple fixation task), actively attended to a foveal target (foveal attention task), performed a reaction time task (cued reaction time task), made saccadic eye movements to visual targets (saccade task), or responded to a repetitious peripheral target (probability task). 2. In a previous paper we demonstrated that monkeys, like humans, responded more quickly to visual targets when the targets followed briefly flashed visual cues (validly cued targets) (Bowman et al. 1993). It has been hypothesized that the cue attracts attention to its locus and results in faster reaction times (Posner 1980). In the present physiological studies, visual cues consistently excited these neurons when they were flashed in the receptive field. Such activity might signal a shift of attention. Visual targets that fell within the receptive field and that immediately followed the cue evoked relatively weak responses. This response was due to a relative refractory period. 3. Next we tested attentional processes in these tasks that were independent of the visual response to the cue. We placed the cue outside of the receptive field and the target within the receptive field. We found that 23% of these cells had a significant decrease in their firing rate to validly cued targets in their receptive fields under these conditions. Strong responses were evoked by the same target when the cue was flashed in the opposite hemifield (invalidly cued targets). Thus this group of neurons responded best when attention was directed toward the opposite hemifield. 4. For another group of parietal cells (13%) there was an enhanced response to targets in the visual receptive field when the cue was in the same hemifield. For the remaining 64% of the cells there was no significant modulation in this task. 5. The cued reaction time task involved exogenous control of attention; the sensory cue gave spatial and temporal direction to attention. We used several other tasks to test for endogenous control of attention.(ABSTRACT TRUNCATED AT 400 WORDS)

Visual receptive field properties in kitten pretectal nucleus of the optic tract and dorsal terminal nucleus of the accessory optic tract

1993 ◽  
Vol 70 (2) ◽  
pp. 814-827 ◽  
Author(s):  
C. Distler ◽  
K. P. Hoffmann
Keyword(s):  
Discharge Rate ◽  
Age Groups ◽  
Optic Tract ◽  
Visual Response ◽  
Stimulus Movement ◽  
Cortical Input ◽  
Preferred Direction ◽  
Pretectal Nucleus ◽  
Adult Cats ◽  
Contralateral Eye

1. Neurons in the pretectal nucleus of the optic tract (NOT) and dorsal terminal nucleus of the accessory optic tract (DTN) were recorded in anesthetized and paralyzed kittens on postnatal days 18 to 48 (P18-P48) as well as in adult cats. 2. Spontaneous as well as stimulus driven discharge rates of NOT-DTN neurons in the youngest kittens (P18-P23) are significantly lower than in older kittens (P27-P33) or adult cats. 3. Visual latencies of NOT-DTN neurons in P18-P23 kittens are significantly longer than in P27-P33 kittens. They further decrease as the animals reach adulthood. 4. Already in the youngest animals recorded in this experimental series (P18) NOT-DTN neurons were selective for ipsiversive horizontal stimulus movement. When expressed as the difference between response strength during stimulation in the preferred and the nonpreferred direction, P18-P23 NOT-DTN neurons are less direction selective than NOT-DTN cells in older animals. However, the normalized directional tuning expressed as percent change in discharge rate per degree change in stimulus direction away from the preferred direction (where discharge rate is set 100%) is about equal in all age groups. 5. NOT-DTN neurons in P18-P23 kittens respond to a rather limited range of stimulus speeds with an optimum at approximately 10 degrees/s. In P27-P33 kittens, NOT-DTN neurons increase their responsive range to higher stimulus speeds. As the animals approach adulthood, the range of effective stimulus speeds further broadens to include very low ones. 6. In P18-P23 kittens, the majority of NOT-DTN neurons is exclusively activated by the contralateral eye; only a few neurons receive an additional input from the ipsilateral eye. In P27-P48 kittens, the influence of the ipsilateral eye has significantly increased but with the majority of NOT-DTN cells still being dominated by the contralateral eye. Finally, in adults, a further strengthening of the ipsilateral input leads to a more binocularly balanced input to NOT-DTN cells. 7. Electrical stimulation in areas 17 and 18 did not elicit orthodromic action potentials in NOT-DTN neurons before P27. Thus the cortical input to the NOT-DTN in kittens becomes functional only at 4 wk of age. 8. In conclusion, the significant changes of visual response properties of NOT-DTN neurons coincide with the time when the cortical input to the NOT-DTN becomes functional.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Demonstration of artificial visual percepts generated through thalamic microstimulation

2007 ◽  
Vol 104 (18) ◽  
pp. 7670-7675 ◽  
Author(s):  
John S. Pezaris ◽  
R. Clay Reid
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Visual Prosthesis ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Visual Response ◽  
Prosthetic Device ◽  
Visual Spatial ◽  
Lateral Geniculate ◽  
Spatial Coordinates ◽  
Saccade Task ◽  
Dorsal Lateral Geniculate

Electrical stimulation of the visual system might serve as the foundation for a prosthetic device for the blind. We examined whether microstimulation of the dorsal lateral geniculate nucleus of the thalamus can generate localized visual percepts in alert monkeys. To assess electrically generated percepts, an eye-movement task was used with targets presented on a computer screen (optically) or through microstimulation of the lateral geniculate nucleus (electrically). Saccades (fast, direct eye movements) made to electrical targets were comparable to saccades made to optical targets. Gaze locations for electrical targets were well predicted by measured visual response maps of cells at the electrode tips. With two electrodes, two distinct targets could be independently created. A sequential saccade task verified that electrical targets were processed not in motor coordinates, but in visual spatial coordinates. Microstimulation produced predictable visual percepts, showing that this technique may be useful for a visual prosthesis.

Influence of habitat pattern on orientation during host fruit location in the tomato fruit fly, Neoceratitis cyanescens

2007 ◽  
Vol 97 (6) ◽  
pp. 637-642 ◽  
Author(s):  
T. Brévault ◽  
S. Quilici
Keyword(s):  
Host Plants ◽  
Tomato Fruit ◽  
Visual Image ◽  
Fruit Fly ◽  
Fruit Flies ◽  
Visual Signals ◽  
Visual Response ◽  
Field Cage ◽  
Host Fruit ◽  
Bright Orange

AbstractFruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly, Neoceratitis cyanescens (Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.

scholarly journals Visual Response Properties and Visuotopic Representation in the Newborn Monkey Superior Colliculus

1997 ◽  
Vol 78 (5) ◽  
pp. 2732-2741 ◽  
Author(s):  
M. T. Wallace ◽  
J. G. McHaffie ◽  
B. E. Stein
Keyword(s):  
Superior Colliculus ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Spatial Summation ◽  
Visual Space ◽  
Field Size ◽  
Visual Response ◽  
Response Latencies ◽  
Developmental Models ◽  
Response Properties

Wallace M. T., J. G. McHaffie, and B. E. Stein. Visual response properties and visuotopic representation in the newborn monkey superior colliculus. J. Neurophysiol. 78: 2732–2741, 1997. Visually responsive neurons were recorded in the superior colliculus (SC) of the newborn rhesus monkey. The receptive fields of these neurons were larger than those in the adult, but already were organized into a well-ordered map of visual space that was very much like that seen in mature animals. This included a marked expansion of the representation of the central 10° of the visual field and a systematic foveal to peripheral increase in receptive field size. Although newborn SC neurons had longer response latencies than did their adult counterparts, they responded vigorously to visual stimuli and exhibited many visual response properties that are characteristic of the adult. These included surround inhibition, within-field spatial summation, within-field spatial inhibition, binocularity, and an adult-like ocular dominance distribution. As in the adult, SC neurons in the newborn preferred a moving visual stimulus and had adult-like selectivities for stimulus speed. The developmentally advanced state of the functional circuitry of the newborn monkey SC contrasts with the comparative immaturity of neurons in its visual cortex. It also contrasts with observations on the state of maturation of the newborn SC in other developmental models (e.g., cat). The observation that extensive visual experience is not necessary for the development of many adult-like SC response properties in the monkey SC may help explain the substantial visual capabilities shown by primates soon after birth.

scholarly journals Auditory signals evolve from hybrid- to eye-centered coordinates in the primate superior colliculus

2012 ◽  
Vol 108 (1) ◽  
pp. 227-242 ◽  
Author(s):  
Jungah Lee ◽  
Jennifer M. Groh
Keyword(s):  
Superior Colliculus ◽  
Reference Frame ◽  
Reference Frames ◽  
Visual Response ◽  
Response Patterns ◽  
Related Activity ◽  
Visual Spatial ◽  
Auditory Representation ◽  
Auditory Signals ◽  
Visual Targets

Visual and auditory spatial signals initially arise in different reference frames. It has been postulated that auditory signals are translated from a head-centered to an eye-centered frame of reference compatible with the visual spatial maps, but, to date, only various forms of hybrid reference frames for sound have been identified. Here, we show that the auditory representation of space in the superior colliculus involves a hybrid reference frame immediately after the sound onset but evolves to become predominantly eye centered, and more similar to the visual representation, by the time of a saccade to that sound. Specifically, during the first 500 ms after the sound onset, auditory response patterns ( N = 103) were usually neither head nor eye centered: 64% of neurons showed such a hybrid pattern, whereas 29% were more eye centered and 8% were more head centered. This differed from the pattern observed for visual targets ( N = 156): 86% were eye centered, <1% were head centered, and only 13% exhibited a hybrid of both reference frames. For auditory-evoked activity observed within 20 ms of the saccade ( N = 154), the proportion of eye-centered response patterns increased to 69%, whereas the hybrid and head-centered response patterns dropped to 30% and <1%, respectively. This pattern approached, although did not quite reach, that observed for saccade-related activity for visual targets: 89% were eye centered, 11% were hybrid, and <1% were head centered ( N = 162). The plainly eye-centered visual response patterns and predominantly eye-centered auditory motor response patterns lie in marked contrast to our previous study of the intraparietal cortex, where both visual and auditory sensory and motor-related activity used a predominantly hybrid reference frame ( Mullette-Gillman et al. 2005 , 2009 ). Our present findings indicate that auditory signals are ultimately translated into a reference frame roughly similar to that used for vision, but suggest that such signals might emerge only in motor areas responsible for directing gaze to visual and auditory stimuli.

scholarly journals An Association between Auditory–Visual Synchrony Processing and Reading Comprehension: Behavioral and Electrophysiological Evidence

2017 ◽  
Vol 29 (3) ◽  
pp. 435-447
Author(s):  
Julia Mossbridge ◽  
Jacob Zweig ◽  
Marcia Grabowecky ◽  
Satoru Suzuki
Keyword(s):  
Reading Comprehension ◽  
Lexical Processing ◽  
Temporal Patterns ◽  
Reading Performance ◽  
Visual Signals ◽  
Orthographic Processing ◽  
Cluttered Environments ◽  
Multimodal Signals ◽  
Visual Spatial ◽  
Electrophysiological Evidence

The perceptual system integrates synchronized auditory–visual signals in part to promote individuation of objects in cluttered environments. The processing of auditory–visual synchrony may more generally contribute to cognition by synchronizing internally generated multimodal signals. Reading is a prime example because the ability to synchronize internal phonological and/or lexical processing with visual orthographic processing may facilitate encoding of words and meanings. Consistent with this possibility, developmental and clinical research has suggested a link between reading performance and the ability to compare visual spatial/temporal patterns with auditory temporal patterns. Here, we provide converging behavioral and electrophysiological evidence suggesting that greater behavioral ability to judge auditory–visual synchrony (Experiment 1) and greater sensitivity of an electrophysiological marker of auditory–visual synchrony processing (Experiment 2) both predict superior reading comprehension performance, accounting for 16% and 25% of the variance, respectively. These results support the idea that the mechanisms that detect auditory–visual synchrony contribute to reading comprehension.

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