Search results for " visual"
showing 10 items of 1041 documents
Wavelength dependence of the optomotor response in zebrafish (Danio rerio)
2003
Abstract The action spectrum of motion detection in zebrafish (Danio rerio) was measured using the optomotor response in the light adapted state. The function has a single maximum at 550–600 nm, and is similar to the spectral sensitivity function of the L-cone type in the mid and long wavelength range. At shorter wavelengths the values of three of the five fish tested are lower. As in goldfish [Vis. Res. 36 (1996) 4025], the result indicates a dominance of the L-cone type with an inhibitory influence of M- or S-cones. Experiments with a red/green striped cylinder showed that the optomotor response was at minimum whenever the L-cone type was not modulated by the moving pattern. This demonstr…
Remembering what but not where: independence of spatial and visual working memory in the human brain
2001
We report the neuropsychological and MRI investigation of a patient (MV) who developed a selective impairment of visual-spatial working memory (WM) with preservation not only of verbal, but also of visual shape WM, following an ischemic lesion in the cerebral territory supplied by one of the terminal branches of the right anterior cerebral artery. MV was defective in visual-spatial WM whether the experimental procedure involved arm movement for target pointing or not. Also, in agreement with the role generally assigned to visual-spatial WM in visual imagery. MV was extremely slow in the mental rotation of visually and verbally presented objects. In striking contrast with the WM deficit, MV'…
Contrast sensitivity after refractive lens exchange with a multifocal diffractive aspheric intraocular lens
2013
Purpose: To evaluate distance and near contrast sensitivity (CS) under photopic and mesopic conditions before and after refractive lens exchange (RLE) and implantation of the aspheric AcrySof ReSTOR (SN6AD3 model) intraocular lens (IOL) Methods: Sixty eyes of 30 consecutive patients after RLE underwent bilateral implantation with the aspheric AcrySof ReSTOR IOL. The patients sample was divided into myopic [n=15, mean spherical equivalent (SE) -6.87± 2.03 diopters (D)] and hyperopic (n=15, mean SE +4.52±1.14 D) groups. Monocular uncorrected visual acuity at distance and near (UCVA and UCNVA, respectively) and monocular best corrected visual acuity at distance and near (BCVA and BCNVA, respec…
Swimming-style synesthesia.
2010
The traditional and predominant understanding of synesthesia is that a sensory input in one modality (inducer) elicits sensory experiences in another modality (concurrent). Recent evidence suggests an important role of semantic representations of inducers. We report here the cases of two synesthetes, experienced swimmers, for whom each swimming style evokes another synesthetic color. Importantly, synesthesia is evoked also in the absence of direct sensory stimulation, i.e., the proprioceptive inputs during swimming. To evoke synesthetic colors, it is sufficient to evoke the concept of a given swimming style e.g., by showing a photograph of a swimming person. A color-consistency test and a S…
Conceptual implicit memory: a developmental study.
1995
The widely accepted standpoint that implicit memory emerges earlier in development than explicit memory, and is more stable from childhood to adult age, is based on experimental data essentially collected in perceptual tasks. The present study was aimed at investigating whether these findings still hold when a more conceptual task is used. We compared the performance of children at two age levels (2nd and 4th grades) on a category-exemplar generation task. Results showed that performances of the two groups were comparable when the target items were typical of their categories, as in Experiment 2, and for a subset of the items in Experiment 1. However, the older children outperformed the you…
Titchener's T with flanks.
2018
Abstract Flanks were added to Titchener's (1901) T-illusion figure to test its susceptibility to context stimuli. The addition of a second divided line yielded H-type figures, and the addition of a second undivided line, +-type figures. The lengths of the Ts' undivided lines was expected to be overestimated relative to the lengths of the divided lines, when all lines were about equally long, and the illusion was expected to become smaller when one or two gaps had been introduced between the lines. Results conformed to the predictions. The amount of illusion was larger for the no-gap H than the T, and was almost annihilated with the two-gaps H, with 3 out of 14 observers showing an inverse r…
Sensitivity of the central visual field in 70- to 81-year-old male athletes and in a population sample.
1994
The sensitivity of the central visual field (0°–30°) was studied using an automatic Octopus 500E perimeter in elderly male athletes and in a population sample of men of corresponding age. The athletes (N=96) were endurance and power athletes, who were still active in competitive sports with training histories spanning tens of years. The athletes’ results were compared with those of a sample of men of the same age (70–81 years, N=41) randomly selected from the local population register. The sensitivity values of the athletes, and the endurance athletes in particular, were significantly better than those of the controls, with differences varying from 1 to 2.5 dB in the different areas of the …
Preclinical dementia: an Italian multicentre study on amnestic mild cognitive impairment
2006
<i>Background:</i> Different rates and cognitive predictors of conversion to dementia have been reported in subjects with different kinds of mild cognitive impairment (MCI). <i>Methods:</i> A prospective, 24-month follow-up study, involving 269 subjects who strictly fulfilled criteria for the amnestic MCI. <i>Results:</i> Conversion rate to dementia was 21.4% per year. Seventy-nine out of the 83 individuals who developed dementia were affected by probable Alzheimer’s disease (AD). Among others, at the 24-month follow-up 24.1% were still affected by amnestic MCI, 13.3% had changed their neuropsychological profile of impairment and 17.2% were cognitively no…
Serial position effects in dementia of the Alzheimer type.
1998
<b>Background: </b>The aim of the present study was to analyse serial position effects for immediate and delayed free recall in patients with dementia of the Alzheimer type and controls. <b>Experiment 1:</b> 44 patients with dementia of the Alzheimer-type and 24 non-demented controls were asked for immediate and delayed free recall of 12 schematic drawings of common objects presented at the rate of 10 s/picture. Steep primacy effects were obtained at all delays in controls. By contrast, primacy effects were significantly impaired in patients with dementia at all delays of recall. Small immediate and delayed recall recency effects were found in both, patients and cont…
Prospective visual evaluation of apodized diffractive intraocular lenses
2006
To evaluate distance, intermediate, and near visual performance in patients who had multifocal apodized diffractive intraocular lens (IOL) implantation.Fernández-Vega Ophthalmological Institute, Oviedo, Spain.The best corrected distance visual acuity, best distance-corrected near visual acuity, intermediate visual acuity, distance contrast sensitivity under photopic and mesopic conditions, and patient satisfaction were measured in 325 patients and 335 patients who had bilateral implantation of the model SA60D3 IOL (AcrySof ReSTOR, Alcon) and model SN60D3 IOL (AcrySof Natural ReSTOR), respectively.At the 6-month postoperative visit, binocular best corrected distance acuity with the ReSTOR IO…