Individual Fitness Research Articles

Transgenerational effects of stress on reproduction strategy in the mixed mating plant Lamium amplexicaule

BackgroundThe theory of Condition Dependent Sex predicts that – everything else being equal – less fit individuals would outcross at higher rates compared with fitter ones. Here we used the mixed mating plant Lamium amplexicaule, capable of producing both self-pollinating closed flowers (CL), alongside open flowers (CH) that allow cross pollination to test it. We investigated the effects of abiotic stress – salt solution irrigation – on the flowering patterns of plants and their offspring. We monitored several flowering and vegetative parameters, including the number and distribution of flowers, CH fraction, and plant size.ResultsWe found that stressed plants show an increased tendency for self-pollination and a deficit in floral and vegetative development. However, when parentally primed, stressed plants show a milder response. Un-stressed offspring of stressed parents show reversed responses and exhibit an increased tendency to outcross, and improve floral and vegetative development.ConclusionsIn summary, we found that stress affects the reproduction strategy in the plants that experienced the stress and in subsequent offspring through F2 generation. Our results provide experimental evidence supporting a transgenerational extension to the theories of fitness associate sex and dispersal, where an individual’s tendency for sex and dispersal may depend on the stress experienced by its parents.

Habitat-induced changes in forage quality and implications for fitness in Plateau Pika (Ochotona curzoniae)

Abstract Plateau pikas (Ochotona curzoniae) play a keystone role in the alpine meadow ecosystem on the Qinghai–Tibetan Plateau (QTP). For decades, QTP grasslands have become degraded to some degree, largely as a result of heavy livestock grazing. Concomitantly, the abundance of plateau pikas has increased dramatically as grassland degradation has altered the vegetation community structure and dominant species, shifting the plant nutrient contents toward higher protein conditions that favor them. Considerable research supports the hypothesis that the quantity and quality of food limit herbivore populations. Here, we examined the relationship between the availability of essential amino acids in the diets of plateau pikas and the degree of meadow degradation associated with livestock grazing intensity through a field survey, as well as the fitness of individuals by laboratory feeding experiments with 2 pelleted chows containing 0.26% and 0.45% methionine. Sulfur-containing methionine and cystine were the most limiting amino acids in the diets of pikas. During the pika breeding season, the concentrations of most essential acids, particularly methionine and cystine, were higher in heavily degraded meadows than in lightly and moderately degraded meadows. Individuals fed 0.45% methionine exhibited enhanced cell-mediated immunity, reduced intensity of coccidian infection, and increased concentrations of gonadotropin-releasing hormone, luteinizing hormone, estradiol, progesterone, and testosterone compared to those fed 0.26% methionine. These results showed that heavily degraded meadows provided relatively high-quality food that improved individual fitness, suggesting that the high-methionine food in the heavily degraded meadows may be a key factor in the generation and maintenance of high-density populations of plateau pikas.

The Relationship of Cardiorespiratory Fitness, Physical Activity, and Coronary Artery Calcification to Cardiovascular Disease Events in CARDIA Participants.

Moderate-to-vigorous-intensity physical activity (MVPA), cardiorespiratory fitness (CRF), and coronary artery calcification (CAC) are associated with cardiovascular disease (CVD) risk. While a U-shaped relationship between CRF or MVPA and CAC has been reported, the presence of CAC among highly fit individuals might be benign. We examined interactive associations of CRF or MVPA and CAC with outcomes and evaluated the relationship of CRF and MVPA to CAC incidence. CARDIA participants with CAC assessed in 2005-06 were included (n=3,141, mean age 45). MVPA was assessed by self-report and accelerometer. CRF was estimated with a maximal graded exercise test. Adjudicated CVD events and mortality data were obtained through 2019. CAC was reassessed in 2010-11. Cox models were constructed to assess hazard ratios (HRs) for CVD, coronary heart disease (CHD), and mortality in groups defined by CAC presence/absence and lower/higher CRF or MVPA levels. Logistic models were constructed to assess associations with CAC incidence. Adjustment was made for sociodemographic and CVD risk factors. Relative to participants with no CAC and higher CRF, the adjusted HRs for CVD were 4.68 for CAC and higher CRF, 2.22 for no CAC and lower CRF, and 3.72 for CAC and lower CRF. For CHD, the respective HRs were 9.98, 2.28, and 5.52. For mortality, the HRs were 1.15, 1.58, and 3.14, respectively. Similar findings were observed when MVPA, measured either by self-report or accelerometer, was substituted for CRF. A robust inverse association of CRF and accelerometer-derived MVPA with CAC incidence was partly accounted for by adjusting for CVD risk factors. In middle-aged adults, CRF and MVPA demonstrated an inverse association with CAC incidence but did not mitigate the increased cardiovascular risk associated with CAC, indicating that CAC is not benign in individuals with higher CRF or MVPA levels.

Alpine viper in changing climate: thermal ecology and prospects of a cold-adapted reptile in the warming Mediterranean

In a rapidly changing thermal environment, reptiles are primarily dependent on in situ adaptation because of their limited ability to disperse and the restricted opportunity to shift their ranges. However, the rapid pace of climate change may surpass these adaptation capabilities or elevate energy expenditures. Therefore, understanding the variability in thermal traits at both individual and population scales is crucial, offering insights into reptiles' vulnerability to climate change. We studied the thermal ecology of the endangered Greek meadow viper (Viperagraeca), an endemic venomous snake of fragmented alpine-subalpine meadows above 1600 m of the Pindos mountain range in Greece and Albania, to assess its susceptibility to anticipated changes in the alpine thermal environment. We measured preferred body temperature in artificial thermal gradient, field body temperatures of 74 individuals in five populations encompassing the entire geographic range of the species, and collected data on the available of temperatures for thermoregulation. We found that the preferred body temperature (Tp) differed only between the northernmost and the southernmost populations and increased with female body size but did not depend on sex or the gravidity status of females. Tp increased with latitude but was unaffected by the phylogenetic position of the populations. We also found high accuracy of thermoregulation in V.graeca populations and variation in the thermal quality of habitats throughout the range. The overall effectiveness of thermoregulation was high, indicating that V.graeca successfully achieves its target temperatures and exploits the thermal landscape. Current climatic conditions limit the activity period by an estimated 1278 h per year, which is expected to increase considerably under future climate scenarios. Restricted time available for thermoregulation, foraging and reproduction will represent a serious threat to the fitness of individuals and the persistence of populations in addition to habitat loss due to mining, tourism or skiing and habitat degradation due to overgrazing in the shrinking mountaintop habitats of V.graeca.

Integrating Dynamic Time Warping and K-means clustering for enhanced cardiovascular fitness assessment

The appropriate measurement of cardiovascular ’Performance Enhancement’ is critical for improving physical fitness and overall health. Traditional methods, effective as they are, often rely on complex, cumbersome equipment, limiting their practical use for real-time, dynamic exercise evaluation. Thus, understanding the intricate relationship between physiological responses and exercise ‘Performance Enhancement’ using wearable technology is essential for tailoring effective fitness regimes. This study involved 52 participants, utilizing Garmin Vivosmart 5 wearables to analyze heart rate time series during the YMCA Three-Minute Step Test, assessing fitness levels and characterizing personalized heartbeat dynamics. The study employed Dynamic Time Warping (DTW) for clustering these time series into high and low VO2max groups. Additionally, heart rate dynamics were examined using K-means clustering to identify distinct patterns during exercise—namely ‘Efficient Adaptation’, ‘Balance Under Pressure’, ‘Active Strain’, and ‘Efficiency Improvement’ clusters. This analysis demonstrated that non-trained individuals showed higher ‘Active Strain’ and ‘Efficiency Improvement’ dynamics and lower ‘Efficient Adaptation’ dynamics, indicating the exercise’s varied effectiveness based on training level. This method provides a novel approach for identifying individual fitness levels and the efficacy of specific exercises, enabling personalized physical activity planning.

Intraspecific variation in group structure arises due to environmentally-mediated directional dispersal in a cooperative breeder.

Many cooperatively breeding species live in groups with complex structure-large group sizes, low and variable kin structure, and multiple breeding pairs. Since these mixed-kin groups typically form because of immigration of unrelated individuals of both sexes in addition to limited offspring dispersal, differences in patterns of dispersal can generate variation in group structure, even within the same species or population. Here, we examine how environmentally mediated dispersal patterns influence variation in group structure in the plural breeding superb starling (Lamprotornis superbus), an avian cooperative breeder that inhabits a spatiotemporally variable savanna environment and forms mixed-kin groups with variable group sizes and more than one breeding pair per group. Using 4068 genome-wide polymorphic loci and fine-scale, remotely sensed ecological data from 22 groups sampled across a nearly 200 km2 environmental gradient in central Kenya, we find evidence of not only frequent and long-distance dispersal in both sexes (low isolation-by-distance and weak genetic structure), but also directional dispersal from small groups in lower quality habitat with low normalised difference vegetation index (NDVI) to large groups in higher quality habitat with high NDVI. Additionally, we find stronger genetic structure among groups in lower quality habitat, and higher genetic diversity and lower relatedness of groups in higher quality habitat. Previous work using long-term data from groups in the same population has shown that groups with lower relatedness are larger and have more breeding pairs. Long-distance, directional dispersal to maximise individual fitness can thus lead to smaller and simpler kin-based social groups in lower quality habitat, but larger and more complex mixed-kin groups in higher quality habitat. Such intraspecific, within-population variation in group structure, including variation in kin structure of social groups, could have profound implications for the relative importance of the evolutionary mechanisms (i.e. direct vs. indirect fitness benefits) underlying the formation of cooperative societies.

Social, not genetic, programming of development and stress physiology of a colonial seabird.

Phenotypic differences often stem from genetic/maternal differences and/or early-life adaptations to local environmental conditions. In colonial animals, little is known on how variation in the social environment is embedded into individual phenotypes, nor what the consequences are on individual fitness. We conducted an experimental cross-fostering study on king penguins (Aptenodytes patagonicus), exchanging eggs among 134 pairs breeding in high-density (67 pairs) or low-density (67 pairs) areas of the same breeding colony. We investigated differences in parent and chick phenotypes and survival in relation to the density of their origin and foster environment. Adults breeding in colony areas of high density exhibited decreased resting behaviour and increased aggression and vigilance, increased hypometabolism during incubation fasts, and more moderate corticosterone responses shaped by exposure to chronic stressors (e.g. constant aggression by neighbours). Chick phenotypes were more influenced by the environment in which they were raised than their genetic/maternal origin. Chicks raised in high-density colonial environments showed enhanced weight gain and survival rates regardless of the density of their genetic parents' breeding areas. Our study experimentally shows advantages to breeding in colonial areas of higher breeder densities in king penguins, and highlights the importance of social settings in shaping phenotype expression in colonial seabirds.

Inbreeding avoidance, competition and natal dispersal in a pair-living, genetically monogamous mammal, Azara's owl monkey (Aotus azarae).

Natal dispersal is an important life-history stage influencing individual fitness, social dynamics of groups and population structure. Understanding factors influencing dispersal is essential for evaluating explanations for the evolution and maintenance of social organization, including parental care and mating systems. The social and mating systems of Azara's owl monkeys (Aotus azarae) are infrequent among mammals; these primates are pair-living, serially and genetically monogamous and both sexes directly care for offspring. To evaluate the role that competition and inbreeding avoidance play in shaping dispersal patterns, we used 25 years of demographic and genetic data to examine how variation in timing of natal dispersal is related to social (adult replacements, step-parents, births and group size) and ecological factors (seasonal abundance of resources) in a wild population of A. azarae in Formosa, Argentina. We found that all males and females dispersed from their natal groups, but subadults delayed dispersal when a step-parent of the opposite sex joined the group, indicating that they may perceive these step-parents as potential mates. Dispersal was more probable when resource conditions were better, regardless of age. Overall, agonistic conflict over food and potential mates with adults in the natal group, as well as inbreeding avoidance, contribute to regulating dispersal.

The effect of frailty on mortality and hospital admission in patients with benign pleural disease in Wales: a cohort study

Pleural disease is common, representing 5% of the acute medical workload, and its incidence is rising, partly due to the ageing population. Frailty is an important feature and little is known about disease progression in patients with frailty and pleural disease. We aimed to examine the effect of frailty on mortality and other relevant outcomes in patients diagnosed with pleural disease. In this cohort study in Wales, the national Secure Anonymised Information Linkage databank was used to identify a cohort of individuals diagnosed with non-malignant pleural disease between Jan 1, 2005, and March 1, 2023, who were not known to have left Wales. Frailty was assessed at diagnosis of pleural disease using an electronic Frailty Index. The primary outcome was time from diagnosis to all-cause mortality for all patients. Data were analysed using multilevel mixed-effects Cox proportional hazards regression adjusting for the prespecified covariates of age, sex, Welsh Index of Multiple Deprivation quintile, smoking status, comorbidity, and subtype of pleural disease. 54 566individuals were included in the final sample (median age 66years [IQR 47-77]; 26 477 [48·5%] were female and 28 089 [51·5%] were male). By the end of the study period, 25 698 (47·1%) participants had died, with a median follow-up of 1·0years (IQR 0·2-3·6). There was an association between frailty and all-cause mortality, which increased as frailty worsened. Compared with fit individuals, there was increasing mortality for those with mild frailty (adjusted hazard ratio 1·11 [95% CI 1·08-1·15]; p<0·0001), moderate frailty (1·25 [1·20-1·31]; p<0·0001), and severe frailty (1·36 [1·28-1·44]; p<0·0001). Independent of age and comorbidities, frailty status at diagnosis of pleural disease appeared to be useful as a prognostic indicator. Patients with moderate or severe frailty had a rapid decline in health. Future patients should be assessed for frailty at the time of diagnosis of pleural disease and might benefit from optimised care and advance care planning. Cardiff University's Wellcome Trust iTPA funding award.

Airports for the genetic rescue of a former agricultural pest

The intensification of agricultural practices and urbanisation are widespread causes of biodiversity loss. However, the role of artificial habitats in genetic rescue is an aspect that is not well understood. Implementing genetic rescue measures to improve gene flow and maintain a viable population of keystone species is a crucial prerequisite for promoting diverse and resilient ecosystems. Landscape fragmentation and modern agricultural methods have caused the decline and the isolation of the remnant colonies of the endangered European ground squirrel (Spermophilus citellus) throughout its range. However, the artificial habitat, such as airport fields with regular grass mowing, provides suitable conditions for this grassland specialist. We measured home range size and genetic variation of seven souslik colonies in western Slovakia. Based on the 6904 ddRAD SNPs, we found significantly higher individual heterozygosity in colonies on airports compared to colonies on pastures. This indicates a potential for higher fitness of individuals from airport colonies, which can serve as a source for evidence-based translocations. Such an intervention can preserve the genetic diversity of small and isolated populations in the region. We emphasize that conservation management strategies would be strengthened including a specific focus on human-made grassland habitats.

A modified dispersed frequency and phase consensus algorithm based on differential evolution and credibility weighting matrix

In distributed antenna array systems, accurate synchronization of the frequency and phase of the transmission signals among subarrays is a premise for beamforming. To solve this problem, a modified dispersed frequency and phase consensus (MDFPC) algorithm, which is based on differential evolution (DE) and the credibility weighting matrix, is proposed in this paper. DE algorithm is adopted to optimize the mixing matrix of MDFPC algorithm, and the convergence speed of consensus algorithm can be improved. Moreover, Lanczos method is adopted to calculate the fitness of individuals during optimization, thus the computation amount of the eigenvalue decomposition of the large-scale, sparse and symmetric mixing matrix can be effectively reduced. In addition, the influence of the transmission distance between subarrays on the received Signal-to-Noise Ratio (SNR) is considered, and the credibility weighting matrix can be obtained. Then the contribution of low-credible frequency and phase messages to the iterative updated values can be decreased by the credibility weighting matrix, thus more accurate frequency and phase updated values can be obtained in each iteration. It is shown from simulation results that the proposed algorithm can further reduce the phase synchronization error by at least 8% and achieve at least 18% convergence speed improvement compared to dispersed frequency and phase consensus (DFPC) algorithm.

Runs of homozygosity reveal contrasting histories of inbreeding across global lineages of the edible porcini mushroom, Boletus edulis.

Inbreeding, the mating of individuals that are related through common ancestry, is of central importance in evolutionary and conservation biology due to its impacts on individual fitness and population dynamics. However, while advanced genomic approaches have revolutionised the study of inbreeding in animals, genomic studies of inbreeding are rare in plants and lacking in fungi. We investigated global patterns of inbreeding in the prized edible porcini mushroom Boletus edulis using 225 whole genomes from seven lineages distributed across the northern hemisphere. Genomic inbreeding was quantified using runs of homozygosity (ROHs). We found appreciable variation both among and within lineages, with some individuals having over 20% of their genomes in ROHs. Much of this variation could be explained by a combination of elevation and latitude, and to a lesser extent by predicted habitat suitability during the last glacial maximum. In line with this, the majority of ROHs were short, reflecting ancient common ancestry dating back approximately 200-1700 generations ago, while longer ROHs indicative of recent common ancestry (less than approximately 50 generations ago) were infrequent. Our study reveals the inbreeding legacy of major climatic events in a widely distributed forest mutualist, aligning with prevailing theories and empirical studies of the impacts of historical glaciation events on the dominant forest tree species of the northern hemisphere.

Leveraging camera traps and artificial intelligence to explore thermoregulation behaviour.

Behavioural thermoregulation has critical ecological and physiological consequences that profoundly influence individual fitness and species distributions, particularly in the context of climate change. However, field monitoring of this behaviour remains labour-intensive and time-consuming. With the rise of camera-based surveys and artificial intelligence (AI) approaches in computer vision, we should try to build better tools for characterizing animals' behavioural thermoregulation. In this study, we developed a deep learning framework to automate the detection and classification of thermoregulation behaviour. We used lizards, the Rough-tail rock agama (Laudakia vulgaris), as a model animal for thermoregulation. We colour-marked the lizards and curated a diverse dataset of images captured by trail cameras under semi-natural conditions. Subsequently, we trained an object-detection model to identify lizards and image classification models to determine their microclimate usage (activity in sun or shade), which may indicate thermoregulation preferences. We then evaluated the performance of each model and analysed how the classification of thermoregulating lizards performed under different solar conditions (sun or shade), times of day and marking colours. Our framework's models achieved high scores in several performance metrics. The behavioural thermoregulation classification model performed significantly better on sun-basking lizards, achieving the highest classification accuracy with white-marked lizards. Moreover, the hours of activity and the microclimate choices (sun vs shade-seeking behaviour) of lizards, generated by our framework, are closely aligned with manually annotated data. Our study underscores the potential of AI in effectively tracking behavioural thermoregulation, offering a promising new direction for camera trap studies. This approach can potentially reduce the labour and time associated with ecological data collection and analysis and help gain a deeper understanding of species' thermal preferences and risks of climate change on species behaviour.

Beyond Simple vs Complex: Exploring the Nuanced and Unexpected Effects of Spatial Environmental Complexity on Mating Patterns and Female Fecundity.

The features of the physical environment set the stage upon which sexual selection operates, and consequently can have a significant impact on variation in realized individual fitness, and influence a population's evolutionary trajectory. This phenomenon has been explored empirically in several studies using fruit flies (Drosophila melanogaster) which have found that changing the spatial complexity of the mating environment influenced male-female interaction dynamics, (re)mating rates and realized female fecundities. However, these studies did not explore mating patterns, which can dramatically alter the genetic composition of the next generation, and frequently only compared a single, small "simple" environment to a single larger "complex" environment. While these studies have shown that broadly changing the characteristics of the environment can have big effects on reproductive dynamics, the plasticity of this outcome to more subtle changes has not been extensively explored. Our study set out to compare patterns of mating and courtship between large- and small-bodied males and females, and female fecundities in both a simple environment and two distinctly different spatially-complex environments. We found that realized offspring production patterns differed dramatically between all three environments, indicating that the effects of increasing spatial complexity on mating outcomes are sensitive to the specific type of environmental complexity. Furthermore, we observed female fecundities were higher for flies in both complex environments compared those in the simple environment, supporting its role as a mediator of sexual conflict. Together, these results show that the union of gametes within a population can be greatly influenced by the specific spatial features of the environment and that while some outcomes of increased environmental complexity are likely generalizable, other phenomena like mating patterns and courtship rates may vary from one complex environment to another.

Inbreeding and cognition in wild populations: a relationship that remains unnoticed

Anthropogenic activities are causing a steep decline of wildlife populations. Increased inbreeding in shrinking populations can substantially curb individual fitness and population viability. One potentially important but largely ignored component of inbreeding depression may be cognitive decline. Cognition affects an animal's capacity to respond to environmental disturbance, which, in the face of global change, may make the difference between persistence and extinction. While the effects of inbreeding on cognitive performance have been relatively well documented in humans, they remain largely unexplored in natural populations. Here we review the current (limited) knowledge on whether and how inbreeding impinges on animals' cognitive abilities. Insights into the relationship between inbreeding and cognition could prove valuable not only for comprehending the development and evolution of cognition but also for conservation.

Social selection analysis reveals limited effect of neighbors' traits in Tree swallows.

Social interactions are ubiquitous in nature and can shape the fitness of individuals through social selection. This type of selection arises when phenotypes of neighbors influence the fitness of a focal individual. Quantifying social selection is crucial to better characterize the overall selective landscape. For example, if intraspecific competition is strong, traits that are beneficial for an individual could be detrimental to competitors. In this study, we quantified social selection acting on three key ecological traits (body mass, wing length, and laying date) in wild Tree swallow (Tachycineta bicolor) females. We used reproductive success measured at three stages throughout the breeding season as fitness proxies to assess selection acting at those decisive moments. We also quantified the effects of environment on selection using measures of conspecifics' density, type of agricultural landscape, and presence of interspecific competitors. Overall, we found no strong evidence of social selection on these traits in our study system, although there were marginally nonsignificant selection gradients suggesting the positive effect of larger neighbors. Environmental variables affected reproductive success but did not strongly affect social selection gradients. Our study calls for more social selection estimates to be reported across environments to better understand its importance in wild populations.

Adult telomere length is positively correlated with survival and lifetime reproductive success in a wild passerine.

Explaining variation in individual fitness is a key goal in evolutionary biology. Recently, telomeres, repeating DNA sequences capping chromosome ends, have gained attention as a biomarker for body state, physiological costs, and senescence. Existing research has provided mixed evidence for whether telomere length correlates with fitness, including survival and reproductive output. Moreover, few studies have examined how the rate of change in telomere length correlates with fitness in wild populations. Here, we intensively monitored an insular population of house sparrows, and collected longitudinal telomere and life history data (16 years, 1225 individuals). We tested whether telomere length and its rate of change predict fitness measures, namely survival, lifespan and annual and lifetime reproductive effort and success. Telomere length positively predicted short-term survival, independent of age, but did not predict lifespan, suggesting either a diminishing telomere length-survival correlation with age or other extrinsic factors of mortality. The positive association of telomere length with survival translated into reproductive benefits, as birds with longer telomeres produced more genetic recruits, hatchlings and reared more fledglings over their lifetime. In contrast, there was no association between telomere dynamics and annual reproductive output, suggesting telomere dynamics might not reflect the costs of reproduction in this population, potentially masked by variation in individual quality. The rate of change of telomere length did not correlate with neither lifespan nor lifetime reproductive success. Our results provide further evidence that telomere length correlates with fitness, and contribute to our understanding of the selection on, and evolution of, telomere dynamics.

Digest: Sexually selected traits can affect individual fitness and trait evolution in a butterfly species.

Wedell and Kemp ([2024]. Examined the importance of female sexual preferences for male UV reflectance on offspring viability and the evolution of male traits in the butterfly Eurema hecabe. Female preferences were found to have multiple consequences, including increased trait value, higher offspring viability, and reduced mutational load. These findings highlight that female sexual preferences for specific male traits can also have further consequences for individual fitness and evolution of specific morphological characteristics.

Spatial, social, and environmental factors influencing natal dispersal in the colonial griffon vulture

Abstract Natal dispersal is a critical trait for individual fitness and the viability, structure, and genetic identity of populations. However, there is a pronounced information gap for large and long-lived species due to the difficulty of monitoring individuals at appropriate spatio-temporal scales. Here we study how individual traits and social and environmental characteristics influence natal dispersal decisions of griffon vultures (Gyps fulvus) using long-term (30 years) monitoring of a large number of individuals marked as nestlings in Spain. Our results show a strong philopatry in both sexes, with some individuals recruiting as breeders on the same cliffs, and even the same nests, where they were born. This philopatric tendency was modulated by the effect of conspecific density on individual parameters and emphasized the importance of conspecific attraction and changes in food availability that may have influenced the increment in colony size and the colonization of new areas. Although further research is needed considering smaller colonies and more isolated population nuclei, our results highlight the importance of long-term studies on long-lived species to understand the factors that determine their population dynamics and their relationship with anthropogenic activities, whose effects should be predicted and managed using conservation criteria.

Triphasic Pulse Stimulation Pattern in Cochlear Implant Users Assessed with Ecap Measure

The rationale for the use of three-phase stimulation for programming the processor of the cochlear implantation system (CI) in patients with deafness is presented. To study the possibilities of using a new type of stimulation, we selected patients after cochlear implantation, with signs of facial nerve stimulation (FNS) in postoperative period. All subjects were previously fitted with an audio processor with individual fitting maps based on traditional biphasic stimulation. The use of three-phase stimulation to prevent FNS is caused by the geometry of the electric current pulses, which allows to reduce the penetrating power of the charge in the tissues and eliminate the effect on the facial nerve, without resorting to reducing the levels of stimulation necessary to create a dynamic range of sound perception. Comparative data of the parameters and the results of audiological testing in 21 patients with symptoms of FNS with traditional (two-phase) and three-phase electrical pulses in the stimulation algorithm of the CI system are presented. The positive effect of three-phase stimulation has been established. The results of the study show a significant increase in sound perception indicators when switching to a three-phase stimulation algorithm.