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91.
92.
Bédard P Proteau L 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2001,138(4):419-431
Movement planning has been shown to be optimized when the participant is permitted to see his or her hand resting on the
starting base prior to movement initiation. However, this proposition is opposed by contradictory results. In the present
study, we wanted to determine whether these conflicting results were caused by procedural differences. The results showed
that seeing one's hand on the starting base did not result in more accurate aiming movement than when this information was
not available. However, lower aiming errors were found when one was asked to foveate the starting base and then the target
prior to movement initiation, but only when no dynamic visual information was available during movement. When an aiming movement
was performed while one's hand was visible in visual periphery, foveating the starting base or not prior to movement initiation
did not modify aiming accuracy. These results suggest that gazing at the starting base and then at the target provides an
eye-based representation of the movement to be performed that can be used by the CNS to plan a manual aiming movement. Information
for better planning of the direction – but not the extent – dimension of an upcoming movement can also be derived from dynamic
visual information available in peripheral vision.
Electronic Publication 相似文献
93.
目的探讨阿魏酸钠注射液治疗视网膜静脉栓塞的临床效果。方法100例(100只眼)视网膜静脉栓塞患者,随机分成治疗组和对照组各50例。对照组给予常规治疗,治疗组给予阿魏酸钠注射液300mg/d静脉滴注,14d为一疗程。测定治疗前后视力、视网膜中央静脉血流速度、视网膜中央动脉平均收缩期峰值血流速度。结果应用阿魏酸钠治疗后,视力明显改善,视网膜中央静脉血流速度和收缩期峰值血流速度显著提高,与对照组治疗后相比均有显著性差异,疗效优于对照组。结论阿魏酸钠治疗视网膜静脉栓塞疗效显著。 相似文献
94.
The first part of the present study used a model of Alzheimers disease in two groups of animals (three monkeys in each), given injections of neurotoxins (monkeys of group I) and physiological saline (monkeys of group II). Before injections, all monkeys were trained to discriminate stimuli containing different types of information (spatial frequency grids and geometrical figures of different colors and with different spatial relationships between objects) and to perform spatial selection. The dynamics of impairments in the characteristics of working memory were identified using delayed differentiation tasks in monkeys of both groups before injections and every two months after injections. Quantitative measures of impairments were made using the entropy of visual recognition, which characterizes uncertainty in decision-taking. The development of Alzheimers disease in rhesus macaques was characterized by a deficit of working memory, resulting from lesions to the two component processes of memory. Impairments of the first of these in monkeys of group I were manifest as a significant increase in entropy, which is associated with correct decision-taking. The magnitude of the increase depended on the type of visual information. Impairments of the second component were characterized by increases in entropy associated with refusals to take decisions and were independent of the delay duration and the type of visual information. Monkeys given injections of physiological saline showed no significant changes in these characteristics. The features of working memory were also studied in the second part of the investigation, using four groups of Rhesus macaques: intact, those with bilateral extirpation of the sulcus principalis or field 7 or both: degradation again identified two components. Entropy associated with this was increased significantly for most of the stimuli tested on monkeys of all extirpation groups as compared with intact animals. Significant differences were found in these characteristics for a number of stimuli, which depended on the location of the structures removed. The characteristics of impairments of the components of working memory resulting in the development of Alzheimers disease showed that the cholinergic mechanisms responsible for sensory processing differ from those involved in decision-taking. The structural-functional organization of the interaction of sensory and cognitive processes controlled by the motivation and attention systems is discussed, as is the role of the associative areas of the cortex.Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 89, No. 10, pp. 1226–1239, October, 2003. 相似文献
95.
N. Kato 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1987,68(3):533-540
Summary The postnatal development of thalamocortical projections from the pulvinar to an association cortex of the cat, the crown of the middle suprasylvian gyrus, was studied by using both HRP and evoked field potentials. From birth onward, the pulvinar sends dense fibres to this cortical area, but the cortical laminar distribution of the afferents was found to change markedly with aging. An orthograde HRP study showed that at birth and up to 2 weeks of age, the terminals are distributed mainly in layer I, whereas in adult cats and kittens older than 1 month, the terminals are found largely in and around layer IV and only sparsely in layer I. After HRP injections exclusively into layer I of the crown, numerous thalamic neurones were retrogradely labelled in both the ventroanterior-ventrolateral complex (VA-VL) and the pulvinar in 5-day-old kittens, but in the VAVL alone in 2-month-old kittens. In agreement with these anatomical findings, stimulation of the pulvinar elicited a surface-negative, depth-positive potential in 1-week-old kittens, indicating the existence of a large current sink in layer I; however, it induced a surface-positive, depth-negative potential in 1month-old kittens, reflecting the presence of a strong current sink in the deep cortical layers. 相似文献
96.
Harold B. Dowse Mitchell S. Dushay Jeffrey C. Hall John M. Ringo 《Behavior genetics》1989,19(4):529-542
Free-running locomotor activity and eclosion rhythms ofDrosophila melanogaster, mutant at thedisconnected (disco) locus, are substantially different from the wild-type phenotype. Initial periodogram analysis revealed little or no rhythmicity (Dushayet al., 1989). We have reanalyzed the locomotor activity data using high-resolution signal analysis (maximum-entropy spectral analysis, or MESA). These analyses, corroborated by autocorrelograms, uncovered significant residual circadian rhythmicity and strong ultradian rhythms in most of the animals tested. In this regard thedisco mutants are much like flies expressing mutant alleles of theperiod gene, as well as wild-type flies reared throughout life in constant darkness. We hypothesize that light normally triggers the coupling of multiple ultradian oscillators into a functional circadian clock and that this process is disrupted indisco flies as a result of the neural lesion.This work was supported in part by NIH Grant FM-33205. 相似文献
97.
目的总结喉全切除术食管发声训练和效果。方法对我院自1998年6月~2003年6月的59例喉癌、下咽癌全喉切除术后患者,进行食管发声康复训练。结果53例(89.8%)获得不同程度的发声功能,46例无喉者的言语水平接近正常喉言语水平,他们的最大发音时程较长、听距较远,言语可懂度高,较流利;7例发音效果差,但言语可懂度仍高;不能发声者仅6例。结论与其它发声重建相比,食管发声能很快学会发基本音,并具有发声成功率高、发声质量良好等优点。 相似文献
98.
M. C. Morrone D. C. Burr H. D. Speed 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1987,67(3):635-644
Summary Visual evoked potentials (VEPs) were recorded from cat cortex (area 17) before, during and after application of the GABA blocker bicuculline (iontophoretic or topical). The stimuli comprised a test sinusoidal grating, and a mask grating oriented either parallel or orthogonal to the test. Both test and mask alternated in contrast at different temporal frequencies. VEPs were averaged in synchrony with the test contrast reversal, so the mask did not contribute directly to the averaged VEP response. Before application of bicuculline, both parallel and orthogonal masks attenuated the amplitude of VEPs and changed the phase response, but in different ways. Orthogonal masks lowered the slope of the contrast response curve without affecting extrapolated threshold, while parallel masks caused the curve to shift to the right. Orthogonal masks increased the phase advance, while parallel masks eliminated it. During application of bicuculline, neither parallel nor the orthogonal masks attenuated VEP amplitudes. The results suggest that although the mechanisms for the action of parallel and orthogonal masks are clearly distinct, both are mediated by the GABA-ergic inhibitory system. Given this evidence, measurement of VEP contrast response curves may provide a simple non-invasive technique for monitoring visual inhibition in humans. 相似文献
99.
100.
采用生物素结合的葡聚糖胺顺行示踪法研究了大鼠视皮质主要胼胝体投射区即17/18a交界区胼胝体轴突的生后发育和形态。在生后5天时,此交界区胼胝体轴突从白质向灰质Ⅰ层垂直生长,在灰质内仅有极少量的侧支抽芽。至生后13天时,皮质Ⅰ层最先出现致密的由胼胝体轴突终支组成的终末丛。到生后17天时,类似的终末丛也见于皮质Ⅱ/Ⅲ,Ⅴ和Ⅵ层,这种分布型式与成年大鼠者相似。以上结果表明,绝大部分胼胝体轴突首先生长到达Ⅰ层并先在Ⅰ层发出终支,然后再在其它皮质层发出侧支及终支,因而提示皮质Ⅰ层在胼胝体联系的生后发育中可能发挥重要作用。 相似文献