PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Visualized analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34Linked to original sources
PubMed1980

Signal detection analysis of visual flicker in deaf and hearing individuals.

A comparison of deaf and hearing subjects on temporal visual resolving power was conducted within a signal-detection paradigm. Subjects were required to make forced-choice judgments of a visual-flicker task under three stimulus probability conditions (0.25, 0.50, 0.75). A total of 600 trials were given each subject from which d' and Beta, indices for sensory sensitivity and response bias respectively, were computed. No significant differences existed on sensory sensitivity or response bias which questions some traditional assumptions about sensory compensation.

Adolescent↗
PubMed1987

Properties of the evoked potential generators: current source-density analysis of visually evoked potentials in the cat cortex.

The depth profiles of visually evoked field potentials were recorded in areas 17 and 18 of the cat visual cortex. For comparison, potential profiles evoked by electrical stimulation of the primary afferents and of the nonspecific reticular system were also recorded. From these profiles the current source-density (CSD) distributions were calculated using the one-dimensional CSD method. CSD distributions evoked by the different types of stimuli differ in their amplitudes and time courses by approximately one and two orders of magnitude. Qualitatively, however, they are very similar. Thus, the CSDs can be interpreted as reflecting the same basic pattern of excitatory synaptic activations. This pattern consists of early activation components in the input layers, followed by excitatory synaptic activations in layer III, then in layer II, and in layer V. The basic pattern of cortical activation was found to be modulated by specific features of the visual stimuli. Modulations reflecting contour-versus contrast-contents as well as those reflecting characteristic features of moving patterns have been identified. Most of the CSD components of the cortical activation sequence were obtained from regions extending well beyond the cellular receptive fields in visual cortex. Thus, they reflect nonretinotopic activities. Parameters other than specific features of the visual stimuli have profound influence on cortical CSDs. Nonspecific parameters which have been considered are the general state of cortical excitability, the temporal interactions of successive activities (which are predominantly facilitatory), and the lateral interactions of simultaneous activations from different regions of the visual field (predominantly inhibitory).

Animals↗
PubMed2006

An analysis of visual oddity concept learning in a California sea lion (Zalophus californianus).

We tested a California sea lion for visual oddity learning by presentingproblems composed ofthree two-dimensional black-and-white stimuli, two identical (S-) and one different (S+). In the first experimental stage, a single problem per session was presented until learning criterion was reached. In the second experimental stage, all problems were presented only five times in succession; then a new problem was introduced (six problems/session). In the third experimental stage, each problem was presented only once. The sea lion mastered all stages of oddity learning. A final transfer test with oddity problems composed of completely new stimuli yielded performance significantly above chance. Data analyses suggested learning of specific stimulus properties in the first stage, learning set formation in the second stage, but oddity conceptualization in the third stage.

Animals↗
PubMed1999

GPT.EXE: a powerful tool for the visualization and analysis of general processing tree models.

This paper introduces GPT.EXE, a computer program for designing and implementing general processing tree (GPT) models. First, designing and building GPT models using this program is discussed. The second major emphasis is a description of various statistical procedures that can be carried out with GPT.EXE. There is also a brief section on the on-line documentation of this program. Throughout the text, pictures of windows from the program are displayed to help explain the procedures being described by the text.

Cognition↗
PubMedDate not supplied

Geometric ray tracing analysis of visual acuity after laser in situ keratomileusis.

PURPOSE: Using a geometric ray tracing model, we explain the increase in visual acuity observed in myopic patients after laser in situ keratomileusis (LASIK). METHODS: This study included 37 eyes of 23 patients who underwent LASIK. All patients had myopia and a spectacle-corrected visual acuity of 0.95 or worse. Clinical tests included biometry, corneal topography, pachymetry, and refraction (with and without cycloplegia). Calculations were made by tracing rays through all the refractive surfaces of the eye based on a Le Grand-type theoretical model of the whole eye. RESULTS: Comparison of spectacle-corrected visual acuity of the eye before surgery, the size of the blur circle calculated by ray tracing, and the magnification for the ocular system facilitated a numerical criterion to assess visual acuity by geometric calculation. This criterion was applied to myopic eyes that underwent LASIK, and the maximum increase in spectacle-corrected visual acuity was predicted. An actual increase in visual acuity of approximately 40% of the predicted maximum was observed in patients. CONCLUSIONS: With geometric ray tracing, it was possible not only to obtain an estimate of the visual acuity before LASIK but also to assess the value of the maximum and probable increases in visual acuity after LASIK.

Adult↗
PubMedDate not supplied

A componential analysis of visual object recognition deficits in patients with herpes simplex virus encephalitis.

Five patients with a diagnosis of Herpes Simplex Virus Encephalitis (HSVE) underwent neuropsychological assessment to explore the integrity of their visual perceptual abilities. Selective deficits affecting different levels of the recognition processing were found; impaired recognition abilities were also influenced by selective task requirements, which resulted either in facilitatory or constraining effects on patients' performance. A theoretical model of object recognition (Humphreys & Riddoch, 1987) was taken into account to explain patients' performance. Further, the role of specific components of visual processing was evidenced in explaining the performance of patients affected by HSVE.

Adult↗
PubMed2002

[Analysis of visual prognosis and correlative factors in retinal vein occlusion].

OBJECTIVE: To investigate the visual prognosis, risk factors, complications and the causes of visual deterioration in patients with various types of retinal vein occlusion (RVO). METHODS: Nine hundred and forty-four eyes of 913 patients with various types of RVO were analyzed. The age range of patients was 15 - 89 years (average 52.8 +/- 11.9), and the average follow-up was 20.7 months. The data of the patients were studied by SPSS software. RESULTS: (1) RVO was classified into central RVO (CRVO) in 406 eyes of 391 cases (43.0%), hemi-RVO (HRVO) in 60 eyes of 60 cases (6.4%) and branch RVO (BRVO) in 478 eyes of 462 cases (50.6%). (2) They were subdivided into ischemic type in 633 eyes (67.1%) and non-ischemic type in 311 eyes (32.9%). (3) The visual prognosis: the average initial visual acuity (VA) in CRVO, HRVO and BRVO was 0.36, 0.38 and 0.40 respectively. The average final VA was 0.40 in CRVO (P > 0.05), 0.50 in HRVO (P > 0.05) and 0.58 in BRVO (P < 0.05). (4) The initial VA and prognosis: there was close relationship between initial VA and visual prognosis. If the initial VA >/= 0.5, the final acuity maintained >/= 0.5 in 70.6% in CRVO, 75.0% in HRVO and 84.9% in BRVO. The patients with initial VA </= 0.l had final VA worse than 0.1 in 66.2% of CRVO, 35.7% of HRVO and 25.3% of BRVO (P < 0.01). (5) Low vision and the rate of blindness in RVO: Among the 205 eyes with low vision (21.7%), there were 27.6% with CRVO, 31.7% with HRVO and 17.2% with BRVO (P < 0.01). Among the 160 eyes with blindness (16.9%), There were 27.6% with CRVO, 11.7% with HRVO and 8.6% with BRVO (P < 0.01). (6) The visual prognostic comparison between ischemic type and non-ischemic type: there were 189 of 633 eyes with ischemic type (29.9%) and only l6 of 311 eyes with non-ischemic type (5.1%) had low vision. In the ischemic type, 157 eyes had blindness (25.1%) and 3 eyes with non-ischemic type (1.0%) had blindness (P < 0.01). (7) Risk factors of RVO were hypertension (57.8%), arteriosclerosis (67.4%), high blood viscosity (24.6%), diabetes (6.2%) and primary glaucoma (1.5%). (8) Complications of RVO: cystoid macular edema (CME) 46.7%, retinal neovascularization (RNV) 21.5%, vitreous hemorrhage 11.4% and neovascular glaucoma (NVG) 9.6% (39/406) in CRVO and 1.7% (1/60) in HRVO. (9) Low vision caused by CME was 37.9%, and RNV 29.9%; blindness in CME 19.5% and RNV 23.0%. In 40 eyes with NVG, the final VA was worse than 0.05 in 38 eyes (95.0%). CONCLUSION: The rate of blindness of RVO is high, and the visual prognosis of ischemic type is worse. There is close relationship between the level of initial VA and visual prognosis. CME, RNV and NVG are important causes of blindness.

Adolescent↗
PubMed1992

Computer-based collection and analysis of myoelectric activity of the intestine in horses.

Extracellular myoelectric activity from the terminal ileum, cecum, and colonic pelvic flexure was assessed in 4 adult horses. The collection and analysis of myoelectric data involved the development and use of a computer-based system. After collection, the myoelectric signal was digitally filtered to enhance the activity of interest. The smoothed signal was then processed by use of computer programs designed to identify and count spike-burst activity and estimate burst duration. The intense phases of myoelectric complexes also were identified. The propagation of myoelectric spike-burst activity was assessed over 3 electrode sites to identify the propagative patterns of intestinal motility. There was high correlation between the results of computer-based analysis and those of visual analysis. We concluded that the computer provides a fast, accurate, and reliable means of assessing myoelectric activity.

Animals↗
PubMed1992

The analysis of visual motion: a comparison of neuronal and psychophysical performance.

We compared the ability of psychophysical observers and single cortical neurons to discriminate weak motion signals in a stochastic visual display. All data were obtained from rhesus monkeys trained to perform a direction discrimination task near psychophysical threshold. The conditions for such a comparison were ideal in that both psychophysical and physiological data were obtained in the same animals, on the same sets of trials, and using the same visual display. In addition, the psychophysical task was tailored in each experiment to the physiological properties of the neuron under study; the visual display was matched to each neuron's preference for size, speed, and direction of motion. Under these conditions, the sensitivity of most MT neurons was very similar to the psychophysical sensitivity of the animal observers. In fact, the responses of single neurons typically provided a satisfactory account of both absolute psychophysical threshold and the shape of the psychometric function relating performance to the strength of the motion signal. Thus, psychophysical decisions in our task are likely to be based upon a relatively small number of neural signals. These signals could be carried by a small number of neurons if the responses of the pooled neurons are statistically independent. Alternatively, the signals may be carried by a much larger pool of neurons if their responses are partially intercorrelated.

Animals↗
PubMed1992

A colour-flicker analysis of visual function in patients with retinal detachment.

Patients with a history of retinal detachment were examined by the following tests: (1) setting of an isoluminant match between yellow and green constituent squares of a checkerboard and (2) measurement of the flicker fusion frequency for a contrast-reversal of this yellow-green pattern. The results suggest that the test may provide useful data for assessing the severity of any damage to a given part of the retina. The fusion frequencies range from over 10 Hz (normal) to about 2 Hz for a severely impaired retina. The data for the relative amounts of red and green light needed to achieve a match rarely show any abnormality; thus, a standard anomaloscope test or pseudoisochromatic plates would not detect these deficiencies.

Adult↗
PubMed2005

[Multiple factor analysis of visual function in hypermetropic children].

OBJECTIVE: To investigate the characteristics of hypermetropic children whose visual acuity (VA) is declined or accompanied by esotropia. METHODS: One hundred and ninety children were given optometry, strabismus degree and binocular vision measurement. RESULTS: Declined VA appeared in 170 children, while esotropia occurred in 173. Sixty-one got binocular single vision, 17 had fusion function, and 11 had stereoaculty. Spherical equivalent had a linear relationship with VA (P < 0.01), but not with the strabismus degree (P > 0.05). The influence factors of binocular vision were age of discovery, VA and the strabismus degree, while the stereoaculty was influenced by the strabismus degree, spherical equivalent and VA. CONCLUSION: Low VA and strabismus are the most common complaint in children. Ametropia and strabismus do great harm to juvenile binocular vision, and stereoaculty is damaged seriously. We suggest an early examination of visual function in children.

Adolescent↗
PubMed1991

[The use of microdot immunoenzyme analysis with visual detection for the determination of tularemia antibodies].

The possibility of using the micropoint enzyme immunoassay (EIA) on a nitrocellulose membrane with the visual evaluation of results for the detection of tularemia IgG antibodies in hamadryas baboons at the postvaccinal period has been studied. The sensitivity of this assay has been compared with that of the passive hemagglutination (PHA) test, the microagglutination (MA) test and EIA with the spectrophotometric evaluation of results in plates. As shown in this study, EIA in the above-mentioned modification can be successfully used for the detection of tularemia antibodies in the blood serum. The sensitivity of micropoint EIA has proved to be not inferior to that of EIA in plates, while exceeding the sensitivity of the PHA test 10- to 20-fold and the sensitivity of the MA test 10- to 1,000-fold. This method is simple, reliable, highly sensitive, economic and requires no special equipment, which makes it highly promising for the diagnosis of tularemia and the evaluation of humoral immunity at the postvaccinal period.

Animals↗
PubMed1989

[Immunoenzyme analysis with visual demonstration for detecting antibodies to the tick-borne encephalitis virus].

Good prospects for the use of enzyme immunoassay (EIA) with the simple visual indication of results have been shown with the detection of specific antibodies to tick-borne encephalitis virus in blood serum used as an example. When compared with such highly sensitive method as radioimmunoassay, visual EIA is inferior in both sensitivity and selectivity, but its special advantage is that it requires no instrument for evaluating the result.

Animals↗