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R Nicoletti

Publications and source records attributed to R Nicoletti.

At least 19 recordsLinked to original sources
PubMed1992

Spatial representations of words and nonwords.

The first two experiments investigated whether the representations of words, besides being unitary, are also spatial in nature. Subjects were required to search for target letters in either five-letter words or five-letter nonwords. They were instructed to press the right-side key for one target and the left-side key for the other target. The center item of the letter string was always at fixation. Targets appeared one at a time, located at the second (left side) or the fourth (right side) position within the letter string. The results showed that: a) responses to targets within words were faster than responses to targets within nonwords (the word-superiority effect); b) responses to compatible stimulus-response pairings were faster than responses to incompatible stimulus-response pairings (the spatial compatibility, or, more precisely, the Simon effect); and c) in Experiment 2, left-side targets were responded to faster than right-side targets within nonwords (the left-right scanning effect). It was concluded that representations of both words and nonwords are spatial in nature. Experiment 3 was aimed at testing whether the spatial layout of the representations of words is always along the left-right horizontal dimension, regardless of the topographic transformation of the stimulus. The same words and nonwords used in the previous experiments were shown vertically and the subjects were required to make left-right discriminative responses to upper and lower target letters. The results showed the word-superiority effect but no spatial compatibility effects. It was concluded that the representation of a vertically presented word is vertically arranged.

Adult↗
PubMed1992

[Intestinal transit studied with radiopaque markers in patients with multiple sclerosis].

The patients affected with multiple sclerosis (MS) often complain of constipation. This symptom is little tolerated by the patient; its etiology is still unknown. MS patients often have their movements impaired by disease progress, so that they have to sit down for a long time, or else they exhibit severe problems walking or moving. MS patients also present low intraabdominal pressure during voluntary contraction of abdominal wall muscles. In these patients, the authors suggest to study intestinal transit time by means of radiopaque markers. To this purpose, the radiological follow-up contributes to the setting of colorectal MS dysfunctions by daily controls of the progress of per os radiopaque markers, focusing on colonic transit time and temporary deposit areas. The results show high incidence of anorectal constipation. Thus, the examination can be considered a useful tool in the study of MS dysfunctions and an effective alternative to anorectal manometry.

Colon↗
PubMed1991

New evidence for the perceptual precedence of global information.

Two experiments are reported investigating the order in which global and local information of visual forms is processed. Subjects were presented with compound stimuli and were asked to identify the local level, always consisting of small letters. At the global level, the stimuli could be either large letters, consistent or inconsistent with the local level, or meaningless patterns derived from the large letters by modifying the spatial relations among segments. Results showed that inconsistent stimuli were responded to more slowly than both consistent stimuli and meaningless patterns, which did not differ from each other. This was true both when letters and patterns were presented intermixed, as in experiment 1 or separately, as in experiment 2. The pattern obtained accords well with predictions derived from the perceptual precedence hypothesis which states that global information becomes available at a faster rate than local information. No support for the alternative, post-perceptual, hypothesis was found.

Attention↗
PubMed1991

Is interhemispheric transfer of visuomotor information asymmetric? Evidence from a meta-analysis.

Using a meta-analytic procedure we have analysed 16 studies employing a simple unimanual reaction time (RT) paradigm and lateralized visual stimuli to provide an estimate of interhemispheric transfer time in normal right-handed subjects. We found a significant overall RT advantage of the left visual field over the right and of the right hand over the left. These asymmetries can be explained by a superiority of the right hemisphere for the detection of simple visual stimuli and by a corresponding superiority of the left hemisphere for the execution of the manual response, respectively. Alternatively, they may be interpreted as related to an asymmetry of interhemispheric transmission of visuomotor information, with transfer from the right hemisphere (side of stimulus entry) to the left (side of response generation) faster than in the reverse direction. Although a direct test of these hypotheses is still lacking, we think that the evidence available is more in keeping with the latter possibility.

Arousal↗
PubMed1991

[Recommendations for carrying out nuclear medicine kidney function tests with a gamma camera and computer].

Standardization of nuclear medicine renal studies is required in order to permit the comparison of study results of a patient obtained at different laboratories. Furthermore, standardization is a prerequisite for quality control of the analysis part of the procedure. The guidelines presented here are based on a survey carried out amongst nuclear medicine laboratories in Austria and have been edited and harmonized in a workshop organized by the Austrian Nuclear Medicine Society. The guidelines include detailed descriptions of the requirements of instrumentation, of the methods of acquisition, dosage and radiation dose of the commonly used radiopharmaceuticals and all aspects of the analysis of digital renograms. A comprehensive section deals with the determination of renal clearance from the renogram, further sections cover the usage and recommended methods of captopril renography for the diagnosis of unilateral renal artery stenosis and of the frusemide renogram for the diagnosis of nephropathy and uropathy.

Austria↗
PubMed1991

[Contribution of the CT to a special technique of percutaneous lumbar anesthetic block].

The authors suggest the use of CT for the positioning of a permanent catheter, suitable for lumbar anesthetic block in painful lower limbs syndromes. This technique was employed on 12 patients suffering from vascular diseases of the lower limbs. CT allowed a good visualization of both bone structures and soft tissues, which are essential landmarks for catheter positioning. The catheter was inserted with its anterior end fixed to the anterior abdominal wall, which allowed the patient to manage its own treatment. In all cases we obtained marked symptoms regression, after 5 months of treatment. No such complications were observed as those report in literature. The main contraindication appeared to be the aneurysmatic dilatation of both aorta and iliac arteries.

Female↗
PubMed1990

Evaluation of renal transplant perfusion by functional imaging.

Radionuclide angiography (RNA) is used as a noninvasive method for the evaluation of renal transplant perfusion. The computer processing method generally used, based on regions of interest, is unsatisfactory because it does not permit the regional differentiation of perfusion defects. Furthermore, the subjective delineation of the regions of interest introduces considerable inter-observer variation of results. We developed a processing method which is less operator-dependent and permits the evaluation of local defects; it is based on the concept of functional imaging. The method was evaluated in 62 patient examinations, which were subdivided into four groups: normal transplant perfusion (23 examinations), acute tubular necrosis (ATN) (16), cellular rejection (13), and vascular rejection (10). Quantitative results derived from profile curves were combined with visual estimation of the functional images and yielded a synoptic graph which allowed differentiation into three groups: normal transplant perfusion (sensitivity 0.78, specificity 0.97), ATN or cellular rejection (sens. 0.83, spec. 0.82) and vascular rejection (sens. 0.90, spec. 0.92).

Colloids↗
PubMed1989

Splitting visual space with attention.

If a right-left spatial compatibility effect is observed, it can be maintained that the space has been segmented into right- and left-side parts. The present study aimed at showing a spatial compatibility effect (and, by implication, a right-left subdivision of space) solely attributable to the orienting of attention. Five groups of 8 normal subjects were required to give right-left discriminative responses to stimuli presented within one of six empty boxes arranged in a horizontal row. Reaction times and errors were recorded. The first two experiments showed that a right-left grouping of the boxes occurred regardless of whether subjects' fixation was kept at the intermediate position (Experiment 1) or at one extremity (Experiment 2) of the row. In Experiments 3 and 4, subjects' attention was not aligned with a fixed position but was moved, through peripheral cues, from trial to trial and positioned between different pairs of adjacent boxes. The results showed that the display was again subdivided into two regions and that the reference point for the right-left subdivision was the focus of attention. In Experiment 5, eye position was instrumentally monitored, and subjects' attention was directed by central cues. The results confirmed that the focusing of attention leads to a right-left partitioning of space, with the boundary at the locus of focal attention. In conclusion, we demonstrated, by employing a right-left spatial compatibility paradigm, that directing attention to a position in space brings about a right-left perceptual organization that predominates over that provided by the other egocentric reference axes.

Adult↗
PubMed1989

Quantitative static and dynamic renal scintigraphy with diuresis stimulation in renovascular hypertension.

The results of computer-assisted static and dynamic renal scintigraphy in 57 patients with renovascular hypertension (RVH) and 23 patients with essential hypertension (EH) are presented. The following parameters were quantified: renal size (RS), count density (CD), relative unilateral renal clearance (RRC), mean parenchymal transit time (PTT), difference of time-to-peak of activity (tmaxd) to stenosed minus non-stenosed side, effect of frusemide (FE) and renal parenchymal radionuclide retention (RI). Among 57 stenosed renal arteries we detected 54 (true-positive cases) and missed three (false-negative cases); among 23 patients with EH and no significant haemodynamic renal artery stenosis, we found 21 cases correctly negative and two patients falsely positive. These data yielded a sensitivity of 95% and a specificity of 92%. The quantification of renal radionuclide studies in renal artery stenoses minimizes false-positive results and increases their specificity. This study shows that, because of its sensitivity, quantitative renal scintigraphy reliably allows the assessment of the functional haemodynamic effects of a renovascular lesion (significant stenosis) in the diagnostic work-up and during follow-up after surgical reconstruction or percutaneous transluminal angioplasty (PTA). The evaluation of renal function is in general greatly supported by the quantitative parameters, yet particularly after medication with converting enzyme inhibitors and after intervention.

Diuresis↗
PubMed1989

[Distributed attention and focused attention: different modalities of use].

In the present experiments two different attention modalities were investigated: focused and distributed attention. In Experiment 1 manual choice reaction times to lateralized visual stimuli were measured. Visual stimuli (rectangles or squares) were presented in one of six positions along the horizontal axis. In between each position a digit 1 to 5 was permanently displayed. The subjects were instructed to switch their attention to one of the five digits and to respond as fast as possible to the stimulus target flashed either on the right or on the left of the focus of attention. The only difference in Experiment 2 was that the digit stayed on 100 msec only. The results show the importance of a visual cue (Exp. 1) for focused attention. In the absence of a permanent visual cue (Exp. 2) only distributed attention can be employed.

Adult↗
PubMed1987

[Value of cholescintigraphy in the differential diagnosis of direct hyperbilirubinemia in infancy].

Cholescintigraphy using 99mTc-diethyl-, 99mTc-diisopropyl-, 99mTc-iodo-diethyl- and 99mTc-bro-motrimethyl-IDA was performed in 22 newborns and infants with direct hyperbilirubinaemia. Retrospective evaluation of 99mTc-diethyl- and 99mTc-diisopropyl-IDA (n = 18) showed an efficiency of 66% in the differentiation between extrahepatic biliary atresia and neonatal intrahepatic diseases if the hepatocyte-clearance index and transit time were taken into consideration; the sensitivity of detecting extrahepatic biliary atresia was 100%. Cholestyramine treatment (n = 9) did not increase the efficiency of the test. Efficiency was markedly reduced when the serum direct bilirubin level was above 5.5 mg/dl (94 mumol/l). The gall bladder was not visualized in 13 out of 18 examinations. The prospective and retrospective analysis of 99mTc-iodo-diethyl- and 99mTc-bromo-trimethyl-IDA revealed intrahepatic disease in all 6 infants with serum values up to 12.6 mg/dl (216 mumol/l) direct bilirubin; the gall bladder was not visualized in 4 out of 7 examinations.

Biliary Atresia↗