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排序方式: 共有8192条查询结果,搜索用时 31 毫秒
61.
Tadech Boonpiyathad Willem van de Veen Oliver Wirz Milena Sokolowska Beate Rückert Ge Tan Atik Sangasapaviliya Panitan Pradubpongsa Rattanaporn Fuengthong Pattarawat Thantiworasit Sunee Sirivichayakul Kiat Ruxrungtham Cezmi A. Akdis Mübeccel Akdis 《The Journal of allergy and clinical immunology》2019,143(3):1077-1086.e10
62.
Takeichi N Fukushima J Kurkin S Yamanobe T Shinmei Y Fukushima K 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2003,149(3):380-390
The smooth pursuit system moves the eyes in space accurately while compensating for visual inputs from the moving background
and/or vestibular inputs during head movements. To understand the mechanisms underlying such interactions, we examined the
influence of a stationary textured visual background on smooth pursuit tracking and compared the results in young and adult
humans and monkeys. Six humans (three children, three adults) and six macaque monkeys (five young, one adult) were used. Human
eye movements were recorded using infrared oculography and evoked by a sinusoidally moving target presented on a computer
monitor. Scleral search coils were used for monkeys while they tracked a target presented on a tangent screen. The target
moved in a sinusoidal or trapezoidal fashion with or without whole body rotation in the same plane. Two kinds of backgrounds,
homogeneous and stationary textured, were used. Eye velocity gains (eye velocity/target velocity) were calculated in each
condition to compare the influence of the textured background. Children showed asymmetric eye movements during vertical pursuit
across the textured (but not the homogeneous) background; upward pursuit was severely impaired, and consisted mostly of catch-up
saccades. In contrast, adults showed no asymmetry during pursuit across the different backgrounds. Monkeys behaved similarly;
only slight effects were observed with the textured background in a mature monkey, whereas upward pursuit was severely impaired
in young monkeys. In addition, VOR cancellation was severely impaired during upward eye and head movements, resulting in residual
downward VOR in young monkeys. From these results, we conclude that the directional asymmetry observed in young primates may
reflect a different neural organization of the vertical, particularly upward, pursuit system in the face of conflicting visual
and vestibular inputs that can be associated with pursuit eye movements. Apparently, proper compensation matures later.
Electronic Publication 相似文献
63.
S. Grant M. J. Keating 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1992,89(2):383-396
Summary In the frog, Xenopus laevis, a system of intertectal connections underlies the visual projection from an eye to its ipsilateral tectal lobe and is involved in the topographic representation of binocular visual space. Rotation of one eye in early life may be followed by a radical rearrangement of the connections in this system. The modified pattern which later emerges is that which keeps the visual projection through the ipsilateral eye in topographic registration with the direct visual projection from the contralateral eye to the same tectal lobe. This plasticity requires visual experience.In this paper we describe the time-course and sequence of events by which this plasticity is effected. Following rotation of one eye in larval animals or in animals undergoing metamorphic climax, the earliest evidence of intertectal modification was found 3–4 weeks after metamorphosis. With increasing intervals after metamorphosis an increasing proportion of animals displayed modified intertectal systems. At intermediate intervals many animals showed partial modifications, which were interpreted as transitional stages in the modification process. Analysis of these transitional stages indicated that the sequence of events involved in the elaboration of a modified intertectal system following the experimental alteration of eye alignment exhibits features in common with rearrangements of the system that occur during normal development in response to growth-related alterations in eye alignment. 相似文献
64.
Attention to Color: An Analysis of Selection, Controlled Search, and Motor Activation, Using Event-Related Potentials 总被引:3,自引:0,他引:3
Albertus A. Wijers Gijsbertus Mulder Tsunetaka Okita Lambertus J.M. Mulder Marten K. Scheffers 《Psychophysiology》1989,26(1):89-109
In this study the organization of information processing in a selective search task was examined by analyzing event-related potentials. This task consisted of searching for target letters in a relevant (attended) color. The ERPs revealed two different effects of attention: an early occipital negativity (+/- 150 ms) reflecting feature-specific attention, and a later, central N2b component (+/- 240 ms) reflecting covert orienting of attention. A later, prolonged negativity (search-related negativity) (+/- 300 ms), maximal at Cz, was related to controlled search to letters in the attended color. Detection of relevant targets resulted in a parietal P3b component. Depending on stimulus presentation conditions an earlier response to both attended and unattended targets was found: an N2 component (+/- 250 ms). In these same conditions, C'3-C'4 asymmetries (Corrected Motor Asymmetries--CMA) suggested motor activation at +/- 300 ms, in the same time range as search-related negativity. It was argued that N2 and CMA suggest the existence of a preattentive target detection system, operating in parallel with a slower serial attentive system, as reflected by N2b and search negativity. 相似文献
65.
M. Ohmi I. P. Howard B. Eveleigh 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1986,63(2):387-394
Summary In afoveate animals, and in neonatal or cortically deficient foveate animals, monocular optokinetic nystagmus (OKN) is controlled by directly innervated subcortical nuclei and occurs only in response to temporonasal motion. In higher mammals, the subcortical nuclei receive direct inputs predominantly from the nasal hemiretinae and indirect inputs from the visual cortex. These indirect inputs counterbalance the directional asymmetry of the primitive mechanism. These facts lead to the prediction that the velocity of the slow phase of OKN in the normal human adult should be higher for stimuli moving centripetally rather than centrifugally in each monocular and binocular hemified. The predicted patterns of directional preponderance were found in both monocular and binocular hemifields. Directional asymmetries were still present in monocular hemifields when the central retina was occluded and were reduced when the stimulus was confined to a narrow central strip of the visual field. These results are discussed in terms of the contributions of the central and peripheral retina to directional preponderance.This study is part of DCIEM research contract 97711-3-7595/ 8SE83-00221 and was also supported by NSERC grant A0195 相似文献
66.
Dr. R. A. Burne J. G. Parnavelas C. S. Lin 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1984,53(2):374-383
Summary Response properties of neurons in the visual cortex, area 17, of Long Evans pigmented rats were investigated quantitatively with computer-controlled stimuli. Ninety percent of the cells recorded (296/327) were responsive to visual stimulation. The majority (95%, 281/296) responded to moving images and were classified as complex (44%), simple (27%), hypercomplex (13%) and non-oriented (16%) according to criteria previously established for cortical cells in the cat and monkey. The remaining 5% of the neurons responded only to stationary stimuli flashed on-off in their receptive field. Results of this study indicate that neurons of the rat visual cortex have properties similar to those of cells in the striate cortex of more visual mammals.Supported by grant EY02964, the Biological Humanics Foundation and the Bendix Corporation 相似文献
67.
Functional mapping of color processing by magnetic resonance imaging of responses to selective P- and M-pathway stimulation 总被引:2,自引:0,他引:2
Andreas Kleinschmidt Barry B. Lee Martin Requardt Jens Frahm 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1996,110(2):279-288
Magnetic resonance imaging sensitized to activity-related changes in cerebral blood oxygenation was performed to map responses to selective stimulation of the parvo- and magnocellular visual pathways in calcarine and adjacent ventral occipital cortex of human subjects. In a repetitive stimulation protocol isoluminant chromatic or isochromatic luminance modulation was alternated with steady light of the same mean chromaticity and luminance as a reference condition. While no significant effects were observed for diffuse luminance modulation, two consistent cortical foci responded to isoluminant chromatic stimulation. A strong response was obtained in calcarine cortex at both 2 and 10 Hz, and even for selective S-cone stimulation. A second weaker colorsensitive response was seen bilaterally in the collateral sulcus. Thus, the data not only confirm color-sensitive activation in the collateral sulcus elicited in previous studies by selective cognitive tasks, but additionally demonstrate color-sensitive activation in primary visual cortex. With stimuli defined according to electrophysiological response properties of early visual processing stages, this study complements phenomenological or cognitive approaches in functional mapping of the human visual system. 相似文献
68.
Leonards U Ibanez V Giannakopoulos P 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2002,146(2):172-183
Aging is accompanied by increasing difficulty in working memory associated with the temporary storage and processing of goal-relevant information. Face recognition plays a preponderant role in human behavior, and one might therefore suggest that working memory for faces is spared from age-related decline compared to socially less important visual stimulus material. To test this hypothesis, we performed working memory (n-back) tasks with two different visual stimulus types, namely faces and doors, and compared them to tasks with primarily verbal material, namely letters. Age-related reaction time slowing was comparable for all three stimulus types, supporting hypotheses on general cognitive and motor slowing. In contrast, performance substantially declined with age for faces and doors, but little for letters. Working memory for faces resulted in significantly better performance than that for doors and was more sensitive to on-line manipulation errors such as the temporal order. All together, our results show that even though face perception might play a specific role in visual processing, visual working memory for faces undergoes the same age-related decline as it does for socially less relevant visual material. Moreover, these results suggest that working memory decline cannot be solely explained by increasing vulnerability in prefrontal cortex related to executive functioning, but indicate an age-related decrease in a visual short-term buffer, possibly located in the temporal cortex. 相似文献
69.
Postnatal development of somatostatin-containing neurons in the visual cortex of normal and dark-reared rats 总被引:1,自引:0,他引:1
G. C. Papadopoulos M. E. Cavanagh J. Antonopoulos H. Michaloudi J. G. Parnavelas 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1993,92(3):473-478
Summary The distribution of somatostatin (SRIF)-immunoreactive neurons in the visual cortical areas 17, 18 and 18a of Wistar rats from birth to adulthood was followed in both normal and dark-reared animals. The SRIF neurons show difference in distribution amongst the three cortical areas studied as early as the first postnatal week. Area 17 was distinguished by fewer SRIF cells in the upper layers (I–III), which results in a lower overall density. The SRIF neurons in all areas appeared to increase in numbers up to about 3 weeks and then decline dramatically to adult levels, which were 14–19% of the peak levels. Although this decline was still obvious, it moderated to 25–31% in dark-reared animals. The greatest effect was seen in area 18 where, at 60 days of age, there were twice as many SRIF cells in darkreared as in normal controls. It is suggested that, under conditions of dark rearing, the overall pattern of development of SRIF neurons, being uninfluenced by extrinsic factors, reveals the cells' genetic potential. 相似文献
70.
Neural site of strabismic amblyopia in cats: spatial frequency deficit in primary cortical neurons 总被引:8,自引:0,他引:8
D. P. Crewther S. G. Crewther 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1990,79(3):615-622
Summary The acuities of cells in the primary visual cortex of five tenotomized strabismic cats were measured. Previous behavioural studies have shown such animals to possess a severe amblyopia of approximately 1.5 octaves of spatial frequency, yet the acuities of both retinal ganglion and lateral geniculate X-cells are normal. The receptive fields of the cortical cells sampled were within 5° of the area centralis projection. On average, the acuities of cortical cells driven by the amblyopic eye were nearly 1 octave less than those for the non-deviating eye. However, the best cell acuities for each eye were nearly the same. The relationship between ocular dominance and cell acuity was found to be different for the two eyes despite a symmetrical ocular dominance distribution. The acuity deficit for cells driven through the amblyopic eye was present at all depths along the electrode tracks. We conclude that in this model amblyopia, the initial spatial processing deficit lies in the visual cortex, and most probably in the cells of layer IV. Further-more, the presence of a few cells driven by the amblyopic eye which can perform nearly as well as those from the fellow eye in processing high spatial frequencies gives new insight into the way in which strabismic and deprivation amblyopias differ. 相似文献