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PubMed2001

[Prevention of early postoperative increase in intraocular pressure after phacoemulsification. Comparison of different antiglaucoma drugs].

PURPOSE: To compare the ocular hypotensive effect of different antiglaucomatous eye drops. PATIENTS AND METHODS: This double-blind, randomized study included 119 eyes of 119 patients without other ocular pathology undergoing standardized (one surgeon, Healon) small incision cataract surgery with foldable intraocular lens implantation. The patients were assigned to one of five groups: group 1: 0.25% timolol in Gelrite (extended efficacy, n = 23); group 2: 2% dorzolamide (n = 24); group 3: combination of 0.5% timolol plus 2% dorzolamide (n = 22); group 4: brimonidine (n = 26); group 5: gentamicin (control, n = 24). Intraocular pressure (IOP) was measured preoperatively and at 3 +/- 1, 6 +/- 1, 9 +/- 1, 24 +/- 3, and 48 +/- 3 h postoperatively. Statistical interference was determined by nonparametric group comparisons using Wilcoxon's tests. Absolute values (static comparison) and intraindividual differences from preoperative measurements (dynamic comparisons) were evaluated. All p values should be regarded as descriptive values since they were not formally adjusted for multiplicity. A p value lower than 0.05 therefore indicates local statistical significance. RESULTS: There were no differences between the groups with regard to age, phacoemulsification time, axial length, and preoperative IOP. A statistically significant IOP decrease was measured in group 1 at 24 (p = 0.028) and 48 h (p = 0.007) and in group 3 at 3 (p = 0.001), 6 (p = 0.001), 24 (p = 0.001), and 48 h (p = 0.001) after surgery. A statistically significant IOP increase occurred in group 4 at 3 (p = 0.001), 6 (p = 0.001), and 9 h (p = 0.001) and in group 5 at 3 (p = 0.001), 6 (p = 0.001), 9 (p = 0.001), and 24 h (p = 0.002) postoperatively. Groups 1, 2, and 3 demonstrated lower IOPs at different time points in comparison to groups 4 and 5. Furthermore, group 3 had lower IOPs at 3 h (compared to group 1) and at 6 h (compared to group 2) postoperatively. No statistical differences in IOP were found after 48 h. CONCLUSION: The results favor a combination of 0.5% timolol plus 2% dorzolamide to control postoperative IOP elevation.

Adrenergic alpha-Agonists↗

PubMed2002

A comparison of two time-domain analysis procedures in the determination of .VO(2) kinetics by pseudorandom binary sequence exercise testing.

The purpose of this study was to apply and compare two time-domain analysis procedures in the determination of oxygen uptake (.VO(2)) kinetics in response to a pseudorandom binary sequence (PRBS) exercise test. PRBS exercise tests have typically been analysed in the frequency domain. However, the complex interpretation of frequency responses may have limited the application of this procedure in both sporting and clinical contexts, where a single time measurement would facilitate subject comparison. The relative potential of both a mean response time (MRT) and a peak cross-correlation time (PCCT) was investigated. This study was divided into two parts: a test-retest reliability study (part A), in which 10 healthy male subjects completed two identical PRBS exercise tests, and a comparison of the .VO(2) kinetics of 12 elite endurance runners (ER) and 12 elite sprinters (SR; part B). In part A, 95% limits of agreement were calculated for comparison between MRT and PCCT. The results of part A showed no significant difference between test and retest as assessed by MRT [mean (SD) 42.2 (4.2) s and 43.8 (6.9) s] or by PCCT [21.8 (3.7) s and 22.7 (4.5) s]. Measurement error (%) was lower for MRT in comparison with PCCT (16% and 25%, respectively). In part B of the study, the .VO(2) kinetics of ER were significantly faster than those of SR, as assessed by MRT [33.4 (3.4) s and 39.9 (7.1) s, respectively; P<0.01] and PCCT [20.9 (3.8) s and 24.8 (4.5) s; P<0.05]. It is possible that either analysis procedure could provide a single test measurement of .VO(2) kinetics; however, the greater reliability of the MRT data suggests that this method has more potential for development in the assessment of .VO(2) kinetics by PRBS exercise testing.

Adult↗

PubMed2002

Comparison of BMP-2 and combined IGF-I/TGF-ss1 application in a sheep cervical spine fusion model.

Growth factors have proven to promote spine fusion. However, no comparative evaluation of growth factors in spinal fusion has yet been performed. The purpose of this study was to compare the efficacy and safety of combined IGF-I and TGF-ss1 application with BMP-2 application and autologous cancellous bone graft at an early time point in a sheep cervical spine fusion model. Thirty-two sheep underwent C3/4 discectomy and fusion. They were divided into four groups, according to their treatment: group 1, titanium cage ( n=8); group 2, titanium cage filled with autologous cancellous iliac crest bone grafts ( n=8); group 3, titanium cage coated with a poly-(D,L-lactide) (PDLLA) carrier including BMP-2 (5% w/w) ( n=8); group 4, titanium cage coated with a PDLLA carrier including IGF-I (5% w/w) and TGF-ss1 (1% w/w) ( n=8). Blood samples, body weight and temperature were analysed. Radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8 and 12 weeks. At the same time points, disc space height and intervertebral angle were measured. After 12 weeks, the animals were killed and fusion sites were evaluated using functional radiographic views in flexion and extension. Quantitative computed tomographic scans were performed to assess bone mineral density, bone mineral content and bony callus volume. Biomechanical testing was carried out and the values for range of motion, and neutral and elastic zone were determined. Histomorphological and histomorphometrical analysis were performed and polychrome sequential labelling was used to determine the time frame of new bone formation. The results showed that, in comparison to the group treated with the cage alone (group 1), the cage plus BMP-2 group (group 3) and the cage plus IGF-I and TGF-ss1 group (group 4) demonstrated a significantly higher fusion rate in radiographic findings, a higher biomechanical stability, a more advanced interbody fusion in histomorphometrical analysis, and an accelerated interbody fusion on fluorochrome sequence labelling. In comparison to the bone graft group (group 2), the BMP-2 (group 3) and IGF-I/TGF-ss1 group (group 4) showed significantly less residual motion on functional radiographic evaluation, higher bone mineral density of the callus and higher biomechanical stability in extension, rotation and bending. The BMP-2 group showed significantly less residual motion on functional radiographic evaluation and higher intervertebral bone matrix formation on fluorochrome sequence labelling at 9 weeks in comparison to the IGF-I/TGF-ss1 group. In contrast, the IGF-I/TGF-ss1 group showed a significantly higher bone mineral density of the callus than the BMP-2 group. In comparison to the autologous cancellous bone graft group, both growth factors (BMP-2 and combined IGF-I and TGF-ss1) significantly improved the biomechanical results of interbody fusion. No systemic side effects were observed for either growth factor. On the basis of these preliminary results, it would appear that combined IGF-I/TGF-ss1 application yields equivalent results to BMP-2 application at an early time point in anterior sheep cervical spine fusion.

Animals↗

PubMed2006

The effects of thematic importance on story recall among children with attention deficit hyperactivity disorder and comparison children.

This study examined the recall of televised stories for younger (4-6 years) and older (7-9 years) children with and without attention deficit hyperactivity disorder (ADHD) under two different viewing conditions (toys present/toys absent). Each child watched two Rugrats television programs, once with toys present and once with toys absent. Immediately after viewing a program, the child completed a free recall of the observed story. Comparison children's recall increased more than ADHD children's as importance level increased, and comparison children recalled more information overall than children with ADHD. When toys were present, children with ADHD retold less coherent stories than comparison children, as indexed by smaller correlations between the story units recalled and the order of these units in the story. In summary, children with ADHD demonstrated multiple difficulties in story comprehension. These findings add to our understanding of the differences in higher-order cognitive processing abilities between children with ADHD and comparison children, and suggest important areas of focus in designing more effective academic interventions for children with ADHD.

Attention Deficit Disorder with Hyperactivity↗

PubMed1987

Left ventricular ejection dynamics in hypertrophic cardiomyopathy and aortic stenosis: comparison with the use of Doppler echocardiography.

Left ventricular ejection dynamics of 15 patients with hypertrophic cardiomyopathy (nine obstructive, six nonobstructive) were compared to those in 12 age-matched normal subjects and 10 patients with valvular aortic stenosis by means of combined two-dimensional and Doppler echocardiography. Doppler peak flow velocities in obstructive (HOCM, 2.5 +/- 1.3 m/sec) and nonobstructive (HNCM, 2.6 +/- 0.6 m/sec) hypertrophic cardiomyopathy, as well as in patients with aortic stenosis (AS, 3.6 +/- 1.3 m/sec) were significantly higher than in the normal population (1.0 +/- 0.2 m/sec; p less than 0.001 for all comparisons), but did not differ from each other. The HOCM patients had time to peak velocity (154 +/- 55.7 msec) that was higher than that in both HNCM (86 +/- 8.4 msec) and normal groups (84.5 +/- 8.9 msec; p less than 0.001 for both comparisons), but did not differ from those in AS (117 +/- 52.5 msec). The total ejection time did not differ between HOCM (348.2 +/- 91.1 msec) and AS (328.8 +/- 30.4 msec) groups, but was prolonged in HOCM compared to HNCM (198 +/- 21.0 msec) and normal groups (233 +/- 28.3 msec; p less than 0.001 for both comparisons). The normal and HNCM groups did not differ in time to peak or total ejection time measurements. The percent of flow velocity present in the initial third of the systolic velocity integral for HOCM (44.5% +/- 5.9) and HNCM (49.4% +/- 2.5) groups was greater than for normals (36.2% +/- 5.4; p less than 0.05 for both comparisons), but HOCM values did not differ from HNCM values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Comparison of tetrazolium colorimetric and 51Cr release assays for cytotoxicity determination of dental biomaterials.

OBJECTIVES: The purpose of this study was to compare a methylthiazole tetrazolium (MTT) dye colorimetric method with the standard 51Cr assay as methods of assessing cytotoxicity of dental materials. METHODS: Two MTT-based colorimetric formats, test tube and 96-well microplate methods, were compared to the 51Cr release assay. A series of eight dental materials were evaluated. Cytotoxicity profiles were determined for each test material. A TC50 value (Toxic Concentration required to kill 50% of the cells) was determined for each biomaterial, and these results were used to make statistical comparisons between the methods. RESULTS: The three methods were statistically correlated (p<0.005) by comparison of the eight samples tested. That is, the same rank in toxicity was given by the two tetrazolium sample formats and the 51Cr method. SIGNIFICANCE: The MTT assay was found to have several advantages in comparison to the current standard 51Cr release assay. Optimized in the 96-well format, complete dose response curves and greater sample comparisons can be made rapidly, making the MTT method more economical in time and cost. Furthermore, the MTT method is based on intracellular biochemical changes, measuring cell viability rather than cell morbidity, and has lower detectable limits than the 51Cr release method. There is also less detector chemical binding interference than encountered in the 51Cr release method.

Animals↗

PubMed1990

Comparisons of hemodynamics throughout the life span of the Bio 14.6 cardiomyopathic with the F1B normal hamster.

1. Comparisons of left intraventricular end diastolic and systolic pressures, cardiac output, dP/dt, stroke volume and heart rate were made between the Bio 14.6 cardiomyopathic and F1B normal hamster at 45, 80, 150 and 240 days of age. 2. Comparisons of the ventricular calcium and taurine contents were made between the two strains of hamsters at similar ages. 3. Interstrain comparisons of the 240 day Bio 14.6 with age matched F1B hamsters and intrastrain comparisons with 45 day Bio 14.6 hamsters showed a decreased stroke volume, cardiac output and dP/dt with an increased left intraventricular end diastolic pressure, ventricular weight, ventricular weight/body weight ratio, heart calcium and taurine. 4. Despite the decreased left ventricular systolic pressure and cardiac output in the 80 day and older groups of Bio 14.6 hamsters, no compensatory increase in heart rate was observed.

Age Factors↗

PubMed1983

A comparison of response profiles obtained on the McGill Pain Questionnaire and an adjective checklist.

The response profiles on the McGill Pain Questionnaire (MPQ) were compared with those obtained from a checklist format, consisting of the 78 MPQ words arranged in random order. Both forms were administered to 3 patient groups: (a) primiparae experiencing post-episiotomy pain (n = 60); (b) outpatients attending a rheumatology clinic wisdom tooth extraction (n = 60); and (c) inpatients having undergone wisdom tooth extraction (n = 60). The order of administration was balanced, so that within each patient group 40 patients received either one of the study forms and 20 both, yielding total sample sizes of 120 and 60 for further statistical analyses. Comparison of numbers of words checked in the two formats showed considerable similarity and so for purposes of further comparison, the MPQ structure was imposed on the checklist. This permitted comparison of summary scores, with no significant differences in mean level, with the sole exception of the evaluative subscale. Comparison of individual subgroup profiles on both forms also showed considerable similarity. A second objective was to compare the format in discriminating between patient groups. It was found that the MPQ offered a higher correct classification rate, although there was little in it, with MPQ subgroup scores rather than subscale scores showing marginally better results.

Adult↗

PubMed1992

Quantitation of chronotropic response: comparison of methods for rate-modulating permanent pacemakers.

OBJECTIVES: The aim of this study was to develop a technique for quantitating chronotropic response. BACKGROUND: Although the importance of chronotropic response for optimizing cardiac output during exercise is widely recognized, methods for quantitating the rate-modulating behavior of permanent pacemakers have not been developed. For a method of quantitating chronotropic response to be clinically useful, the rate-modulating characteristics of a pacing system should be defined at the onset of exertion, over a variety of exercise work loads and during recovery. METHODS: Three methods for quantitation of rate modulation were assessed in 10 patients during treadmill exercise testing using the chronotropic assessment exercise protocol with expired gas exchange analysis. To compare the observed chronotropic response with a standard, the "expected" heart rate throughout exercise was calculated by using the concept of heart rate reserve as described by Wilkoff. The pacing rate observed during exercise was analyzed with 1) standard linear regression analysis, 2) comparison of observed and expected pacing rates at the midpoint and end of each quartile of exercise, and 3) integration of the area under the rate-response curve with comparison with the area under the expected curve. RESULTS: With use of a normalized scale relating change in heart rate to change in metabolic work load, with values of heart rate and metabolic work load at rest set to 0 and those at maximal exertion set to a value of 1, the mean y intercept for the study group was 0.10 +/- 0.20 (range -0.14 to +0.45), with a mean slope of 0.81 +/- 0.25 (range 0.31 to 1.19). The correlation coefficient relating change in heart rate to change in exercise work load was a mean of 0.90 +/- 0.09 (range 0.63 to 0.98). Integration of the area under the rate-response curve observed during exercise yielded a mean area that was 101 +/- 36% of that expected. When the range of exercise work loads was divided into quartiles, the area under the observed rate-response curve was 151 +/- 114% of that expected during the first quartile of exercise, 113 +/- 70% during the second, 96 +/- 38% during the third and 92 +/- 20% during the fourth. The mean area under the curve during recovery was 93 +/- 29% of that expected. Although calculation of the observed heart rate as a percent of that expected at the midpoint and end of each quartile of exercise used fewer observations, it provided similar results. CONCLUSIONS: Quantitation of the rate-response curve with comparison with the expected heart rate curve provides accurate methods for quantitation of chronotropic response. Adoption of this method would facilitate comparisons of artificial sensors and provide a framework to address issues of optimal rate modulation.

Age Factors↗

PubMed1990

Cephalometric comparisons of dentofacial parameters between Egyptian and North American adolescents.

The purpose of this study was to develop cephalometric standards for the Egyptian adolescent boys and girls and to compare them to a matched Iowa adolescent sample. The Egyptian sample consisted of 39 boys and 51 girls with a mean age of 12.5 years. The Iowa sample consisted of 33 boys and 22 girls with a mean age of 13.0 years. Basic descriptive statistics were calculated for 35 cephalometric dentofacial parameters. The general linear models procedure, analysis of variance, was used for the comparisons between the groups. F values were calculated for the overall group comparisons, and the statistical significance was predetermined at the 0.05 level of confidence. Comparisons between the boys and girls in both populations indicated that the boys were larger in the linear dimensions of the cranial base and face heights than the girls. Comparisons between the Egyptians and the Iowans indicated that Egyptian boys have a tendency toward bimaxillary dental protrusion and a decreased overbite as compared with Iowa boys. Egyptian girls have a relatively more convex profile and a tendency toward mandibular dental protrusion. When the overall findings are evaluated, it could be concluded that, in general, there is a great similarity in the overall facial morphology between the Egyptian and Iowa populations.

Adolescent↗

PubMed1994

Ten-year change in the use of medical drugs among the elderly--a longitudinal study and cohort comparison.

Longitudinal changes and cohort differences from 1979 to 1989 in the use of prescribed and non-prescribed medical drugs were examined and the connections of drug use to various background variables were analysed in the framework of the Tampere Longitudinal Study of Ageing. In the longitudinal study random samples of men and women born in 1900-09 and 1910-19 (738 persons) were interviewed in 1979 and the survivors (62%) were interviewed again in 1989. In the cohort comparison the 60-69-year-olds studied in 1979 (364 persons) were compared with the 60-69-year-olds in 1989 (395 persons). In the longitudinal setting the number of prescribed drugs increased. In 1989 2 or 3 in 10 persons used at least five prescribed drugs simultaneously. In the cohort comparison there were no differences in the number of prescribed drugs between the two groups of 60-69-year-olds. Use was connected with multimorbidity and poor self-rated health. Both the longitudinal comparison in the group born in 1910-19 and the cohort comparison revealed a significant increase in the use of non-prescribed drugs. The use of analgesics was connected with sex, occupational class, self-rated health and feelings of loneliness. In the use of vitamins, no connection was found with health variables, but they were mostly used by white-collar employees and women. However, when all these variables were controlled for, both analgesics and, in particular, vitamins were used more in 1989 than in 1979. The results suggest that the increase in the use of non-prescribed drugs is mainly due to social and historical factors, by changes both in drug policies, health culture and health behaviour of elderly persons.

Age Factors↗

PubMed1995

Analysis of a vitellogenin gene of the mosquito, Aedes aegypti and comparisons to vitellogenins from other organisms.

A genomic clone of the Aedes aegypti vitellogenin A1 gene was sequenced including 2015 bp of 5' untranscribed sequence, 6369 bp of open reading frame interrupted by two introns, and a short 3' untranslated region. Primer extension was used to identify the transcription initiation site. The amino termini of the large and small subunits were located by N-terminal sequencing of vitellin purified from eggs. The length of the signal sequence and the position of the cleavage site between the two subunits were also determined. Three sequential imperfect repeats were found near the beginning of the small subunit. The sequence of the coding region appears to be polymorphic. Comparison of the signal sequences of seven insect vitellogenin genes revealed several conserved leucines, and a conserved position of an intron. However, the signal sequences are not conserved between these genes and the yolk protein genes of Cyclorraphid Dipteran insects. The cleavage sites between the small and large subunits in the vitellogenins of the mosquito, A. aegypti, sawfly, Athalia rosae, boll weevil, Anthonomus grandis, and silkworm, Bombyx mori are flanked by sequences rich in serine. Pairwise dot matrix analysis at the protein level showed that the mosquito, boll weevil and silkworm vitellogenins are significantly related with approx. 50% similarity. One region of the three insect vitellogenin genes, near the N-terminal of the large subunit, showed the highest levels of similarity, from 57.5 to 64.4%. The position of cysteines in insect vitellogenins is conserved, particularly in the C-terminus of the large subunit. Dot matrix comparison of the mosquito vitellogenin with that of Xenopus laevis and Caenorhabditis elegans showed much lower, but still significant degrees of relationship. Pairwise comparisons of the mosquito vitellogenin and the Drosophila melanogaster yolk proteins did not show significant similarities. Potential regulatory regions in the mosquito VgA1 gene were identified by comparison to regulatory elements known from other organisms, especially D. melanogaster, which could provide useful information for further functional analysis.

Aedes↗

PubMed2005

Bimodal response sensitivity and bias in a test of sustained attention contrasting patients with schizophrenia and bipolar disorder to normal comparison group.

This study examined response discrimination (d') and bias (likelihood ratio) differentials in a computer-generated test of auditory and visual attention functioning. Patients with bipolar disorder (n=42) and schizophrenia (n=47) were contrasted to a normal comparison group (n=89) in two conditions: (a) simple modal responsivity (auditory and visual stimuli) and (b) ipsimodal (auditory/auditory and visual/visual) and crossmodal (auditory/visual and visual/auditory) responding. The results of this study indicated that in the simple modal condition both subject groups showed differential modal preferences but in opposite directions. The schizophrenic group showed a significant visual over auditory preference, committing more auditory commission and omission errors than visual errors. The bipolar group displayed a distinct auditory over visual response preference, committing significantly higher number of visual omission errors. Response bias analysis indicates that both diagnostic groups adopted a more liberal response bias, whereas the comparison group assumed a more conservative approach. For all groups response sensitivity improved as response bias became more neutral. The modal switching results indicated that all three groups tended to commit more commission errors (false alarms) in the auditory crossmodal switching condition (visual/auditory) by comparison with the other switching conditions. Between group comparisons for this condition showed that the schizophrenic group committed significantly more commission errors than the other groups. No significant medication effects were detected.

Adult↗

PubMed2005

Comparison of radioactivity measurements with radionuclide calibrators in the Republic of Korea.

Recognizing the importance of comparisons of radionuclide calibrators in nuclear medicine and the need to provide access to activity standards that are traceable to the international measurement system, the Korea Food & Drug Administration (KFDA) as a national secondary standard dosimetry laboratory (SSDL), started a comparison program in 2002. The first two comparisons were conducted with (131)I (71 participants) and (99m)Tc (72 participants). The results indicated that only 61% of reported activities for (131)I and 65% for (99m)Tc were within +/-5% of the correct value. These numbers increased to 84% for (131)I and 83% for (99m)Tc when a +/-10% limit was applied. Follow-up action on those calibrators with results outside the +/-10% limits only produced a small improvement. There was also a marked difference in performance between the various calibrator types used. The results have shown that such comparisons are necessary to improve the quality of the measurements and to identify those radionuclide calibrators that are not functioning correctly.

Calibration↗

PubMed2005

Hemispheric lateralization of number comparison.

In order to clarify the respective contribution of the right and left posterior parietal cortex (PPC) to number comparison, transcranial magnetic stimulation (TMS) was used to disrupt PPC processing in subjects instructed to determine whether a digit was smaller or larger than 5. Single pulse TMS was applied over the PPC, either unilaterally or bilaterally, 150, 200, or 250 ms after digit presentation. Sham TMS was used as a control condition to take into account the unspecific effects of TMS on reaction time (RT). The main finding of the present study is a significant increase in RTs when comparing digits close to 5 following a disruption either of the left PPC alone or of both PPC simultaneously. The comparison of digits far from 5 was unaltered by disrupting only one PPC but RTs were found increased after bilateral PPC stimulation. These disruptive effects were observed irrespective of the TMS delay. We concluded that coding precise numerical values requires the integrity of the left PPC, as suggested by the deficit in discriminating close digits consequent to its disruption. In contrast, approximate comparisons can be processed either by the left or right PPC, since simultaneous bilateral TMS was needed to alter the comparison of digits far from 5.

Adult↗

PubMed2006

Numerical order and quantity processing in number comparison.

We investigated processing of numerical order information and its relation to mechanisms of numerical quantity processing. In two experiments, performance on a quantity-comparison task (e.g. 2 5; which is larger?) was compared with performance on a relative-order judgment task (e.g. 2 5; ascending or descending order?). The comparison task consistently produced the standard distance effect (faster judgments for far relative to close number pairs), but the distance effect was smaller for ascending (e.g. 2 5) compared to descending pairs (e.g. 5 2). The order task produced a pair-order effect (faster judgments for ascending pairs) and a reverse distance effect for consecutive pairs in ascending order. The reverse effect implies an order-specific process, such as serial search or direct recognition of order for successive numbers. Thus, numerical quantity and order judgments recruited different cognitive mechanisms. Nonetheless, the reduced distance effect for ascending pairs in the quantity task implies involvement of order-related processes in magnitude comparison. Accordingly, distance effects in the quantity-comparison task are not necessarily a process-pure measure of magnitude representation.

Adult↗

PubMed2006

Decoy models for protein structure comparison score normalisation.

A method is described to construct sets of decoy models that can be used to generate a background score distribution for protein structure comparison. The models are derived directly from the two proteins being compared and retain all the essential properties of the structures, including length, density, shape and secondary structure composition but have different folds. As each comparison involves a pair of proteins of the same length, no explicit normalisation is required to adjust for the length of the proteins being compared. This allows substructure (or domain) matches to score almost equally to the comparison of isolated domains. A normalised probability measure was derived that allows joint family/family comparison. The method was applied to some of the CASP6 models for targets with new folds.

Algorithms↗

PubMedDate not supplied

A comparison of neural computations underlying stereo vision and sound localization.

Stereo vision and sound localization are behaviors that help organisms to orient in space. Stereo vision provides information about the distance of an object. In sound localization mainly directional signals are analyzed. Two specific cues, binocular disparities underlying stereo vision, and the interaural time difference, suited to represent azimuth in sound localization, have many computational problems in common, although they are generated in two different modalities. The extraction of both cues requires a comparison of signals that arise from two independent sensors, called two-sensor comparison here. This two-sensor comparison is achieved by algorithms similar to summation, half-wave rectification and multiplication. Since the underlying neurons are band-pass filters, the two-sensor comparison results in ambiguities. These are removed in a hierarchical way in several computational steps, involving squaring, inhibition and across-frequency integration.

Animals↗