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PubMed2003

Effects of redundant and nonredundant bimodal sensory stimulation on heart rate in bobwhite quail embryos.

Research with both animal embryos and human infants has provided evidence that information presented redundantly and in temporal synchrony across sensory modalities (intersensory redundancy) can guide selective attention, perceptual learning, and memory during early development. How this facilitation is achieved remains relatively unexamined. This study examined the effects of redundant versus nonredundant bimodal stimulation on a measure of physiological arousal (heart rate) in bobwhite quail embryos. Results show that quail embryos exposed to concurrent but nonredundant auditory and visual stimulation during the late stages of incubation exhibit significantly elevated heart rates following stimulus exposure and during stimulus reexposure when compared to embryos exposed to redundant and synchronous audiovisual stimulation, unimodal auditory stimulation, or no supplemental prenatal sensory stimulation. These findings indicate a functional distinction between redundant and nonredundant bimodal stimulation during early development and suggest that nonredundant bimodal stimulation during the prenatal period can raise arousal levels, thereby potentially interfering with the attentional capacities and perceptual learning of bobwhite quail. In contrast, intersensory redundancy appears to foster arousal levels that facilitate selective attention and perceptual learning during prenatal development.

Age Factors↗
PubMed1984

The effects of redundant communications on listeners: why different types may have different effects.

Much of our communication is redundant in that we say more than necessary to be informative. How listeners respond to verbal redundancy is important because of its frequency of occurrence and because such knowledge should enable us to increase our understanding of the development of listening skills. Previous research indicated qualitative developmental differences in how listeners respond to differentiating redundancy (several distinguishing features of a referent are mentioned). The present research compared performance with two forms of redundancy: differentiating and structured (e.g., mentioning a distinguishing referential feature and a feature shared by several contiguous stimuli) and investigated causes of differences in responding to the two forms. First- and fifty-graders participated in a referential communication paradigm. Results were discussed in terms of a processing capacity model: Redundancy should facilitate performance only if it decreases processing demands on a listener. Which processing demands will be affected will depend on the specific redundancy and the specific task.

Attention↗
PubMed2006

The role of domain redundancy in genetic robustness against null mutations.

A key question in molecular genetics is why severe gene mutations often do not result in a detectable abnormal phenotype. Alternative networks are known to be a gene compensation mechanism. Gene redundancy, i.e. the presence of a duplicate gene (or paralog) elsewhere in the genome, also underpins many cases of gene dispensability. Here, we investigated the role of partial duplicate genes on dispensability, where a partial duplicate is defined as a gene that has no paralog but which codes for a protein made of domains, each of which belongs to at least another protein. The rationale behind this investigation is that, as a partial duplicate codes for a domain redundant protein, we hypothesised that its deletion might have a less severe phenotypic effect than the deletion of other genes. This prompted us to (re)address the topic of gene dispensability by focusing on domain redundancy rather than on gene redundancy. Using fitness data of single-gene deletion mutants of Saccharomyces cerevisiae, we will show that domain redundancy is a compensation mechanism, the strength of which is lower than that of gene redundancy. Finally, we shall discuss the molecular basis of this new compensation mechanism.

Evolution, Molecular↗
PubMed2002

Intersensory redundancy facilitates prenatal perceptual learning in bobwhite quail (Colinus virginianus) embryos.

Information presented redundantly and in temporal synchrony across sensory modalities (intersensory redundancy) selectively recruits attention and facilitates perceptual learning in human infants. This comparative study examined whether intersensory redundancy also facilitates perceptual learning prenatally. The authors assessed quail (Colinus virginianus) embryos' ability to learn a maternal call when it was (a) unimodal, (b) concurrent but asynchronous with patterned light, or (c) redundant and synchronous with patterned light. Chicks' preference for the familiar over a novel maternal call was assessed 24 hr following hatching. Chicks receiving redundant, synchronous stimulation as embryos learned the call 4 times faster than those who received unimodal exposure. Chicks who received asynchronous bimodal stimulation showed no evidence of learning. These results provide the first evidence that embryos are sensitive to redundant, bimodal information and that it can facilitate learning during the prenatal period.

Acoustic Stimulation↗
PubMed1990

Coactivation in the perception of redundant targets.

Reaction time (RT) to redundant stimuli was investigated while controlling for distraction effects and response competition. In Experiment 1, a redundancy gain was found for 2 target letters with identical features (redundant) compared to trials in which 2 different targets shared the same response assignment (compatible) indicating coactivation of stimulus inputs. No difference in RTs was found between compatible displays and displays containing 2 targets with different responses (incompatible), suggesting (with other evidence) that letters were serially processed. In Experiment 2, a redundancy gain was again found. Unlike in Experiment 1, incompatible displays produced response competition, indicating a redundancy gain with parallel processing. Three forms of redundancy gains operating under specific conditions are discussed.

Adult↗
PubMed1991

Redundancy enhances emotional inferencing by right- and left-hemisphere-damaged adults.

This study investigated the influence of enhanced textual redundancy on affective interpretations made by unilaterally right or left hemisphere brain-damaged adults and normally aging control subjects. Emotional interferences were drawn from linguistic or prosodic material, and redundancy effects were examined within and across stimulus boundaries. Results indicate that heightened semantic redundancy improved the accuracy of linguistic and prosodic judgements of affect for all groups. Correct prosodic judgements were also made more quickly by a subset of each group when textual redundancy was maximized. The facilitory influence of increased redundancy was not attributable solely to perseveration or response rigidity. Possible mechanisms by which semantic redundancy affects cognitive processing are considered.

Aged↗
PubMed2006

The regulatory utilization of genetic redundancy through responsive backup circuits.

Functional redundancies, generated by gene duplications, are highly widespread throughout all known genomes. One consequence of these redundancies is a tremendous increase to the robustness of organisms to mutations and other stresses. Yet, this very robustness also renders redundancy evolutionarily unstable, and it is, thus, predicted to have only a transient lifetime. In contrast, numerous reports describe instances of functional overlaps that have been conserved throughout extended evolutionary periods. More interestingly, many such backed-up genes were shown to be transcriptionally responsive to the intactness of their redundant partner and are up-regulated if the latter is mutationally inactivated. By manual inspection of the literature, we have compiled a list of such "responsive backup circuits" in a diverse list of species. Reviewing these responsive backup circuits, we extract recurring principles characterizing their regulation. We then apply modeling approaches to explore further their dynamic properties. Our results demonstrate that responsive backup circuits may function as ideal devices for filtering nongenetic noise from transcriptional pathways and obtaining regulatory precision. We thus challenge the view that such redundancies are simply leftovers of ancient duplications and suggest they are an additional component to the sophisticated machinery of cellular regulation. In this respect, we suggest that compensation for gene loss is merely a side effect of sophisticated design principles using functional redundancy.

Animals↗
PubMed2005

Filtering redundancies for sequence similarity search programs.

Database scanning programs such as BLAST and FASTA are used nowadays by most biologists for the post-genomic processing of DNA or protein sequence information (in particular to retrieve the structure/function of uncharacterized proteins). Unfortunately, their results can be polluted by identical alignments (called redundancies) coming from the same protein or DNA sequences present in different entries of the database. This makes the efficient use of the listed alignments difficult. Pretreatment of databases has been proposed to suppress strictly identical entries. However, there still remain many identical alignments since redundancies may occur locally for entries corresponding to various fragments of the same sequence or for entries corresponding to very homologous sequences but differing at the level of a few residues such as ortholog proteins. In the present work, we show that redundant alignments can be indeed numerous even when working with a pretreated non-redundant data bank, going as high as 60% of the output results according to the query and the bank. Therefore the accuracy and the efficiency of the post-genomic work will be greatly increased if these redundancies are removed. To solve this up to now unaddressed problem, we have developed an algorithm that allows for the efficient and safe suppression of all the redundancies with no loss of information. This algorithm is based on various filtering steps that we describe here in the context of the Automat similarity search program, and such an algorithm should also be added to the other similarity search programs (BLAST, FASTA, etc...).

Algorithms↗
PubMed1983

Prepreparatory interval effects on redundancy deficit reaction time patterns in schizophrenic and normal subjects using the embedded-set procedure.

The relative influence of genuine "redundancy deficit" and the artifactual effects of prepreparatory interval on measures of the redundancy deficit reaction time pattern (faster reaction time on trials with long preparatory intervals when the interval is of predictable vs. unpredictable length) was investigated in a study using the "embedded-set" procedure. Twenty normal and 20 schizophrenic subjects received two series of reaction time trials containing embedded sets (blocks) of four isotemporal 1-, 3-, and 7-second trials. The 7-second blocks (the blocks of interest for the calculation of redundancy deficit) were preceded by long prepreparatory intervals in one condition and by short intervals for the second. Each subject received both conditions, with the orders counterbalanced. The results indicated redundancy deficit for both schizophrenics and normals with short prepreparatory intervals, but in neither group with long prepreparatory intervals. This suggests that redundancy deficit in the embedded-set procedure (which is normally heavily biased with short prepreparatory intervals) may be more related to the enhancing effect of short prepreparatory intervals on the first (unpredictable) trial of the set than to impaired performance on the fourth (predictable) trial. The finding of similar effects in both schizophrenic and normal subjects raises questions about the specificity of redundancy deficit to schizophrenic reaction time performance. The results were discussed with reference to the original "long run" reaction time procedure for studying the same phenomenon, and theoretical issues related to the interpretation of results from the two procedures were considered.

Attention↗
PubMed2004

On the limitations of redundancies in the improvement of system reliability.

Some program managers share a common belief that adding a redundant component to a system reduces the probability of failure by half. This is true only if the failures of the redundant components are independent events, which is rarely the case. For example, the redundant components may be subjected to the same external loads. There is, however, in general a decrease in the failure probability of the system. Nonetheless, the redundant element comes at a cost, even if it is less than that of developing the first one when both are based on the same design. Identical parts save the most in terms of design costs, but are subjected to common failure modes from possible design errors that limit the effectiveness of the redundancy. In the development of critical systems, managers thus need to decide if the costs of a parallel system are justified by the increase in the system's reliability. NASA, for example, has used redundant spacecraft to increase the chances of mission success, which worked well in the cases of the Viking and Voyager missions. These two successes, however, do not guarantee future ones. We present here a risk analysis framework accounting for dependencies to support the decision to launch at the same time a twin mission of identical spacecraft, given incremental costs and risk-reduction benefits of the second one. We illustrate this analytical approach with the case of the Mars Exploration Rovers launched by NASA in 2003, for which we had performed this assessment in 2001.

Computers↗
PubMed2005

Optimal control of redundant muscles in step-tracking wrist movements.

An important question in motor neuroscience is how the nervous system controls the spatiotemporal activation patterns of redundant muscles in generating accurate movements. The redundant muscles may not only underlie the flexibility of our movements but also pose the challenging problem of how to select a specific sequence of muscle activation from the huge number of possible activations. Here, we propose that noise in the motor command that has an influence on task achievement should be considered in determining the optimal motor commands over redundant muscles. We propose an optimal control model for step-tracking wrist movements with redundant muscles that minimizes the end-point variance under signal-dependent noise. Step-tracking wrist movements of human and nonhuman primates provide a detailed data set to investigate the control mechanisms in movements with redundant muscles. The experimental EMG data can be summarized by two eminent features: 1) amplitude-graded EMG pattern, where the timing of the activity of the agonist and antagonist bursts show slight variations with changes in movement directions, and only the amplitude of activity is modulated; and 2) cosine tuning for movement directions exhibited by the agonist and antagonist bursts, and the discrepancy found between a muscle's agonist preferred direction and its pulling direction. In addition, it is also an important observation that subjects often overshoot the target. We demonstrate that the proposed model captures not only the spatiotemporal activation patterns of wrist muscles but also trajectory overshooting. This suggests that when recruiting redundant muscles, the nervous system may optimize the motor commands across the muscles to reduce the negative effects of motor noise.

Biomechanical Phenomena↗
PubMedDate not supplied

Anteromedial capsular redundancy and labral deficiency in shoulder instability.

BACKGROUND: Redundancy of the anteromedial capsule of the shoulder may persist despite proper tensioning of the capsule and repair of a Bankart lesion during an anteroinferior capsular shift procedure. HYPOTHESIS: A barrel-stitch suture technique incorporated into a capsular shift procedure is effective in achieving satisfactory shoulder stability. STUDY DESIGN: Uncontrolled retrospective review. METHODS: A barrel-stitch technique was used for patients identified as having anteromedial capsular redundancy during a capsular shift procedure for anteroinferior instability. RESULTS: The incidence of anteromedial capsular redundancy and labral deficiency was 49% (38 of 78). Patients with anteromedial capsular redundancy had a significantly greater number of dislocations before surgery (16.1 +/- 21.3 versus 7.4 +/- 7.4) and a greater duration of symptoms (79.8 +/- 84.2 versus 31.6 +/- 32.2 months). The mean postoperative Rowe score of patients with anteromedial capsular redundancy was 88.7 +/- 14.8, with 92% having excellent or good results, compared with 88.9 +/- 14.8 in the remaining patients and 93% excellent or good results. CONCLUSIONS: Anteromedial capsular redundancy is associated with longer preoperative duration of symptoms and more dislocations, but effective treatment can be achieved with a capsular shift procedure augmented with medial capsular imbrication with a barrel stitch.

Adolescent↗
PubMed2006

Combinatorial RNA interference in Caenorhabditis elegans reveals that redundancy between gene duplicates can be maintained for more than 80 million years of evolution.

BACKGROUND: Systematic analyses of loss-of-function phenotypes have been carried out for most genes in Saccharomyces cerevisiae, Caenorhabditis elegans, and Drosophila melanogaster. Although such studies vastly expand our knowledge of single gene function, they do not address redundancy in genetic networks. Developing tools for the systematic mapping of genetic interactions is thus a key step in exploring the relationship between genotype and phenotype. RESULTS: We established conditions for RNA interference (RNAi) in C. elegans to target multiple genes simultaneously in a high-throughput setting. Using this approach, we can detect the great majority of previously known synthetic genetic interactions. We used this assay to examine the redundancy of duplicated genes in the genome of C. elegans that correspond to single orthologs in S. cerevisiae or D. melanogaster and identified 16 pairs of duplicated genes that have redundant functions. Remarkably, 14 of these redundant gene pairs were duplicated before the divergence of C. elegans and C. briggsae 80-110 million years ago, suggesting that there has been selective pressure to maintain the overlap in function between some gene duplicates. CONCLUSION: We established a high throughput method for examining genetic interactions using combinatorial RNAi in C. elegans. Using this technique, we demonstrated that many duplicated genes can retain redundant functions for more than 80 million years of evolution. This provides strong support for evolutionary models that predict that genetic redundancy between duplicated genes can be actively maintained by natural selection and is not just a transient side effect of recent gene duplication events.

Animals↗
PubMed2003

Strength in numbers: exploring redundancy in hierarchical relations across biomedical terminologies.

OBJECTIVES: To investigate three aspects of the redundancy of hierarchical relations across biomedical terminologies: 1) What proportion of the relations is redundant?, 2) Which terminologies tend to overlap with other terminologies?, and 3) Is there a link between redundancy and semantic consistency?. METHODS: Hierarchical relations are counted in the various families of terminologies integrated into the UMLS and an index of redundancy is computed for each relation. Similarity among sources is computed using the classical cosine method. Semantic consistency is evaluated by reference to the UMLS Semantic Network. RESULTS: Overall, 29% of the 1,128,261 relations examined exhibit redundancy. Most similar sources include consecutive versions of terminologies. The link between redundancy and semantic consistency is weak. DISCUSSION: Applications of these findings are discussed, including selecting sources, selecting useful relations, and auditing the categorization of UMLS concepts.

Terminology as Topic↗
PubMed1990

Digital gray-level transformation for the reduction of redundant shadows in rotational panoramic radiography.

In rotational panoramic radiography, the tomographic motion in combination with a slit scanning method make an image layer wide. But some objects outside the image layer are hard to blur and they result to redundant shadows. The gray-level transformation, as one form of digital image processing for the reduction of these redundant shadows, was evaluated. Two methods, the gamma transformation and the histogram flattening method, were examined. A drum scanner was used as the image scanner. The panoramic image on the x-ray film was turned into an 8 bit digital image on the image memory, which had the size of a 512 x 480 matrix. In rotational panoramic radiography, there are low density and contrast regions where redundant shadows of the cervical vertebrae and the mandibular ramus are superimposed on the tomographic image. The histogram of the gray-level was suppressed for the lower gray-levels. The stretching of this gray-level distribution was effective in the reducing redundant shadows. When processed by gamma transformation, the smaller gamma coefficient below 1.0 clarified the tomographic image, and when processed by the histogram flattening method, the setting of the level (L) value around 64-128 effectively reduced the redundant shadows. However, the effectiveness of both gray-level transformations was greatest in restricted cases in which the area where redundant shadows were superimposed on the tomographic image was comparatively large.

Artifacts↗
PubMed2005

Distributed robustness versus redundancy as causes of mutational robustness.

A biological system is robust to mutations if it continues to function after genetic changes in its parts. Such robustness is pervasive on different levels of biological organization, from macromolecules to genetic networks and whole organisms. I here ask which of two possible causes of such robustness are more important on a genome-wide scale, for systems whose parts are genes, such as metabolic and genetic networks. The first of the two causes is redundancy of a system's parts: A gene may be dispensable if the genome contains redundant, back-up copies of the gene. The second cause, distributed robustness, is more poorly understood. It emerges from the distributed nature of many biological systems, where many (and different) parts contribute to system functions. I will here discuss evidence suggesting that distributed robustness is equally or more important for mutational robustness than gene redundancy. This evidence comes from the functional divergence of redundant genes, as well as from large-scale gene deletion studies. I also ask whether one can quantify the extent to which redundancy or distributed robustness contribute to mutational robustness.

Animals↗
PubMed1992

Redundancies, development and the flow of information.

There is increasing evidence for the wide-spread existence of functionally redundant genetic pathways in developmental processes. However, both their significance and manner of evolution are still matters of debate. I will argue here that redundancy of gene actions may, in fact, be a necessary requirement for the development and evolution of complex life forms. One can view development as a process that transmits information from the egg to the adult organism. Transmission of information is, however, always an error-prone process, which can only be safeguarded by including redundancies in the message. Molecular examples for well analysed redundant processes indicate that redundancies may best be understood within a conceptual framework of overlaps between different gene functions.

Animals↗
PubMed2026

Brief Review: Rethinking Colonic Redundancy in Gastroenterology.

BACKGROUND: Dolichocolon (DC), or colonic redundancy, is an elongated and tortuous colon described as early as 1820, yet it remains underrecognized in clinical gastroenterology. Advances in imaging and motility assessment offer new insights into its prevalence, mechanisms, and clinical implications. AIMS: To summarize current evidence on the anatomy, epidemiology, and potential clinical significance of DC and to explore possible pathophysiological mechanisms linking this variant to gastrointestinal disorders. METHODS: A targeted literature review of studies published between 1900 and 2024 was conducted using PubMed and Scopus with search terms including dolichocolon, colonic redundancy, and redundant colon. Publications addressing anatomy, motility, symptom associations, and disease relevance were included. RESULTS: Though epidemiological data are limited, it has been estimated that DC affects 10-20% of the population and is associated with constipation, volvulus, and, possibly, inflammatory bowel disease. Proposed mechanisms include segmental stasis and ischemia in redundant loops, altered neuromuscular signaling, and increased mucosal surface area promoting immune-microbiota interactions. Despite its potential importance, DC is rarely noted in modern radiology reports, contributing to under-recognition in clinical practice. CONCLUSIONS: Colonic redundancy represents a common anatomic variant with potentially overlooked clinical implications. Standardized radiologic characterization and prospective studies are needed to clarify its role in gastrointestinal disorders and to guide future diagnostic and therapeutic approaches.

Humans↗