Individual Differences In Physiology Research Articles

Heart Rate and Oxygen Saturation Internet of Things System (HROS-IoT) Uses Fuzzy Logic

Emergencies in hospitals, including in-hospital cardiac arrest (IHCA), necessitate effective response systems for monitoring vital signs such as heart rate and oxygen saturation. This study aims to develop and evaluate a Heart Rate and Oxygen Saturation Internet of Things (HROS-IoT) system utilizing the MAX30102 sensor and ESP32 microcontroller for real-time health monitoring. The system transmits data to the Blynk application via WiFi, enabling remote monitoring. Testing involved comparing the HROS-IoT system's performance against the commercial LK87 oximeter in measuring heart rate and oxygen saturation before and after meals with five participants. Results indicated that the HROS-IoT system produced heart rate measurements with an average error of 5.2 BPM before meals and 11.3 BPM after meals. Oxygen saturation readings showed an average error of 1% before meals and after meals. Despite minor discrepancies influenced by individual physiological differences and environmental conditions, the HROS-IoT system consistently delivered reliable data. The system's real-time monitoring capability and remote data access enhance proactive health management in hospitals. This study demonstrates the potential of the HROS-IoT system to improve patient outcomes and safety, suggesting further refinements for better accuracy and integration into healthcare settings.

Joint hybrid recursive feature elimination based channel selection and ResGCN for cross session MI recognition

In the field of brain-computer interface (BCI) based on motor imagery (MI), multi-channel electroencephalography (EEG) data is commonly utilized for MI task recognition to achieve sensory compensation or precise human-computer interaction. However, individual physiological differences, environmental variations, or redundant information and noise in certain channels can pose challenges and impact the performance of BCI systems. In this study, we introduce a channel selection method utilizing Hybrid-Recursive Feature Elimination (H-RFE) combined with residual graph neural networks for MI recognition. This channel selection method employs a recursive feature elimination strategy and integrates three classification methods, namely random forest, gradient boosting, and logistic regression, as evaluators for adaptive channel selection tailored to specific subjects. To fully exploit the spatiotemporal information of multi-channel EEG, this study employed a graph neural network embedded with residual blocks to achieve precise recognition of motor imagery. We conducted algorithm testing using the SHU dataset and the PhysioNet dataset. Experimental results show that on the SHU dataset, utilizing 73.44% of the total channels, the cross-session MI recognition accuracy is 90.03%. Similarly, in the PhysioNet dataset, using 72.5% of the channel data, the classification result also reaches 93.99%. Compared to traditional strategies such as selecting three specific channels, correlation-based channel selection, mutual information-based channel selection, and adaptive channel selection based on Pearson coefficients and spatial positions, the proposed method improved classification accuracy by 34.64%, 10.8%, 3.25% and 2.88% on the SHU dataset, and by 46.96%, 5.04%, 5.81% and 2.32% on the PhysioNet dataset, respectively.

A CREAM model optimization method based on fatigue testing experiments and machine learning techniques for maritime transportation applications

Maritime transportation has a crucial position in world trade, but maritime transportation accidents still occur frequently. To assess human errors in maritime transportation more accurately by CREAM and thus improve the reliability of maritime transportation, the study is the first to obtain the quantitative effects of different anti-fatigue capability groups on task performance in the field of maritime transportation by combining fatigue test experiments with machine learning. First, a dataset reflecting the fatigue changes of participants in maritime transportation tasks is constructed by 91 subjects participating in fatigue test experiments. Second, anti-fatigue capability classifications were performed by machine learning algorithms based on Density Peak Clustering Algorithm and fitness. Again, the failure probability correction coefficients of different anti-fatigue capability classes are obtained based on the classification results. Finally, the proposed model optimization method is experimentally verified. The results show that the optimized model is more accurate for the estimation of human-caused errors in maritime transportation. The proposed model effectively improves the inaccuracy of the traditional CREAM due to the lack of attention to individual physiological differences in the reliability assessment.

A Distribution-Adaptive Attention Transformer for Blood Pressure Prediction

Accurately predicting intraoperative blood pressure to prevent intraoperative hypotension is of significant importance. However, the task of intraoperative blood pressure prediction often faces the challenge of substantial sample distribution disparities due to individual physiological differences among patients and the diversity of surgical conditions. These disparities can cause a decline in model performance when encountering inconsistently distributed samples, thus limiting its generalizability in real-world clinical settings. To address this challenge, this paper develops a distribution-adaptive attention strategy aimed at mitigating distributional differences by incorporating statistical information within the model's internal design. The strategy automatically adjusts the model's attention weights by learning statistical information from input windows, enhancing the capability to learn the inherent distribution patterns within non-stationary sequences. Consequently, it reduces performance fluctuations caused by distributional differences. The effectiveness of the proposed distribution-adaptive attention strategy is demonstrated through multiple comparative experiments in the experimental section.

Human-Centric Lighting Research and Policy in the Melanopsin Age.

Beyond visual function, specialized light-sensitive retinal circuits involving the photopigment melanopsin drive critical aspects of human physiology and behavior, including sleep-wake rhythms, hormone production, mood, and cognition. Fundamental discoveries of visual neurobiology dating back to the 1990s have given rise to strong interest from the lighting industry in optimizing lighting to benefit health. Consequently, evidence-based recommendations, regulations, and policies need to translate current knowledge of neurobiology into practice. Here, reviewing recent advances in understanding of NIF circuits in humans leads to proposed strategies to optimize electric lighting. Highlighted knowledge gaps must be addressed urgently, as well as the challenge of developing personalized, adaptive NIF lighting interventions accounting for complex individual differences in physiology, behavior, and environment. Finally, lighting equity issues appear in the context of marginalized groups, who have traditionally been underserved in research on both fundamental visual processes and applied lighting. Biologically optimal light is a fundamental environmental right.

Wearable Personal Core Body Temperature Measurement Considering Individual Differences and Dynamic Tissue Blood Perfusion.

Accurate and continuous measurement of the human core body temperature by a wearable device is of great significance for human health care and disease monitoring. The current wearable thermometers ignore the physiological differences between individuals and the role of blood perfusion in thermoregulation, resulting in insufficient accuracy and limitations in terms of the measurement sites. This study proposed a novel personal model for measuring core body temperature by taking dynamic tissue blood perfusion and individual differences into consideration. The technique facilitates possible accurate core body temperature measurements from the skin surface of the wrist and forehead. First, the personal core body temperature model was established based on the thermal equilibrium between the human body and the measurement device, in which the tissue blood perfusion changes dynamically with tissue temperature. Then, the parameters of the personal model that imply individual physiological differences were obtained based on personal data collected daily. The results show that with the developed personal model, the accuracy of the measured body temperature from the wrist is close to that of the forehead model. The wrist model and the forehead model have a mean absolute error of 0.297 (SD = 0.078)°C and 0.224 (SD = 0.071)°C, respectively, which meets the accuracy and robustness requirements of practical applications. The personal models significantly improve the accuracy compared with that of the group model, especially for the wrist model.

Can exhaled volatile organic compounds differentiate high and low responders to resistance exercise?

Participation in resistance training improves muscle strength and size, as well as reduced risk of chronic disease and frailty. However, the exercise response to resistance training is highly variable. In part this may be attributed to individual physiological differences. Identification of biomarkers that can distinguish between high and low responders to exercise are therefore of interest. Exhaled volatile organic compounds may provide a non-invasive method of monitoring the physiological response to resistance training. However, the relationship between exhaled organic compounds and the acute response to resistance exercise is not fully understood. Therefore, this research will investigate exhaled volatile organic compounds in acute response to resistance exercise with an aim to discover a common group of compounds that can predict high and low responders to standardised resistance training.

Life History Is a Major Source of Adaptive Individual and Species Differences: a Critical Commentary on Zietsch and Sidari (2020)

Zietsch and Sidari (2020) argue that life history theory does not offer an appropriate model for understanding inter-individual trait covariation. We examine in great detail four major claims of Zietsch and Sidari’s critique of life history theory as an explanation of inter-individual covariation among phenotypic, especially psychometric, traits. We review relevant theoretical and empirical research overlooked by Zietsch and Sidari and conduct reanalyses of comparative cross-species “pace-of-life” and human behaviour-genetic data. Our results challenge their arguments concerning (a) the implications for life history theory of the absence of individual-differences-level covariation in a variety of species and (b) the genetic aetiology of psychometric life history covariance. None of the four major claims made by Zietsch and Sidari withstand close scrutiny. Critiques of life history theory, such as the one developed by Zietsch and Sidari, should (if they are to be more persuasive) show what alternative theory might be at least as successful as life history theory in consiliently and parsimoniously explaining patterns of covariation among various traits within and between species, including the predictable absence of such covariation among certain traits. Evolutionary life history theory—as applied to non-human animals and humans—offers one of the broadest and empirically best-supported frameworks for understanding individual differences in physiology, cognition, behaviour, reproduction, and other traits and life outcomes.

Influence of Internal Structure and Composition on Head’s Local Thermal Sensation and Temperature Distribution

A personalized thermal environment is an effective way to ensure a good thermal sensation for individuals. Since local thermal sensation and temperature distribution are affected by individual physiological differences, it is necessary to study the effects of physiological parameters. The purpose of this study was to investigate the effects of internal structures and tissue composition on head temperature distribution and thermal sensation. A new mathematical model based on fuzzy logic control was established, the internal structure and tissue composition of the head were obtained by magnetic resonance imaging (MRI), and the local thermal sensation (LTS) index was used to evaluate the thermal sensation. Based on the mathematical model and the real physiological data, the head temperature and local sensation changes under different parameters were investigated, and the sensitivity of thermal sensation relative to the differences in tissue thickness was analyzed. The results show that skin tissue had the highest influence ( C s k i n = 0.0180 ) on head temperature, followed by muscle tissue ( C m u s c l e = 0.0127 ), and the influence of adipose tissue ( C f a t = 0.0097 ) was the lowest. LTS was most sensitive to skin thickness variation, with an average sensitivity coefficient of 1.58, while the muscle tissue had an average sensitivity coefficient of 0.2, and the sensitivity coefficient of fat was relatively small, at a value of 0.04.

Individual differences in behavior and heart rate variability across the preweaning period in the domestic horse in response to an ecologically relevant stressor

The study of individual differences in behavior and physiology has attracted considerable interest among behavioral biologists. Important questions include how early in life such differences emerge and to what extent they remain stable across development. Due to the demanding nature of longitudinal studies, there is still a lack of information on this in mammals, especially in large, long-lived species. Our aim in this study was to look for stable individual differences in behavior and physiology during early development in the domestic horse and for correlations between the two parameters. We tested 30 Azteca-breed foals kept under standard conditions by briefly separating them from their mother in four repeated tests beginning at the first postnatal week until the foals were six months old, before they were weaned. Individual differences in behavior and heart rate variability of foals in response to brief maternal separations were consistent and were correlated from a very early age. These findings contribute to an understanding of the expression of individual differences in physiology and behavior from a developmental perspective and may help in the future selection of horses for functional contexts that require different levels of reactivity, thereby contributing to horse welfare and to human safety and economy.

Linking autonomic physiology and emotion regulation in preschoolers: The role of reactivity and recovery

Physiological recovery from negative emotions may be important for effective self-regulation, but little is known about recovery processes in children. The current study investigated links between autonomic physiology, anger expressions, and emotion regulation in a sample of eighty-three 3.5-year-olds. Respiratory sinus arrhythmia and pre-ejection period were measured during an anger induction task as parasympathetic and sympathetic indices, respectively. We examined whether preschoolers' anger expressions and emotion regulation behaviors were associated with individual differences in physiology. Autonomic changes were more strongly linked with emotion regulation than with expressed anger. Verbalized regulatory strategies were linked with greater sympathetic reactivity and also with greater recovery. In contrast, attention diversion was associated with blunted patterns of sympathetic reactivity followed by increased sympathetic arousal in the recovery phase. Disengaging from an emotional challenge may be linked with reduced physiological arousal in the short term, this behavior but also appears to have delayed consequences for physiological recovery.

A preliminary investigation into personality and pain in dogs

Abstract Adherence to basic animal welfare standards involves effective monitoring and control of pain, especially in a veterinary setting. Assessment relies on behavioral and physiological indicators. However, individual differences in physiology mediate consistent individual differences in behavior, referred to as personality. Therefore, personality may confound measurements of pain. The current work is a preliminary investigation into whether extraversion and neuroticism are associated with differences in individual behavioral and physiological responses to pain. Twenty dogs were observed during recovery from routine castration in a clinical setting. Core temperature was recorded using infrared thermography on admission, 15 minutes after extubation and every 30 minutes thereafter, until the subject was collected by their owner. Behavior during recovery was scored using Short-Form Glasgow Composite Measure Pain Scale at the same intervals as infrared thermography readings. Personality was measured using Monash Canine Personality Questionnaire–Revised, and owners rated their dog's tolerance to pain on a 5-point Likert scale. Pain score did not have an association with eye temperature discrepancy or core temperature changes from control, indicating it may not predict affective response to pain. More highly extravert subjects had significantly higher pain scores ( P = 0.031), despite experiencing similar tissue damage. More extravert subjects showed significantly greater right eye temperature ( P = 0.035), suggesting hemispheric dominance. Neuroticism had no association with physiological or behavioral responses to pain. Finally, owners were not able to predict their dog's behavioral or physiological response to pain. These results indicate that personality may be a useful clinical tool for assessing individual differences in response to pain, whereas owners' ratings of their dog's response are not reliable.

Investigating Relationships between Reproduction, Immune Defenses, and Cortisol in Dall Sheep.

Life-history theory is fundamental to understanding how animals allocate resources among survival, development, and reproduction, and among traits within these categories. Immediate trade-offs occur within a short span of time and, therefore, are more easily detected. Trade-offs, however, can also manifest across stages of the life cycle, a phenomenon known as carryover effects. We investigated trade-offs on both time scales in two populations of Dall sheep (Ovis dalli dalli) in Southcentral Alaska. Specifically, we (i) tested for glucocorticoid-mediated carryover effects from the breeding season on reproductive success and immune defenses during parturition and (ii) tested for trade-offs between immune defenses and reproduction within a season. We observed no relationship between cortisol during mating and pregnancy success; however, we found marginal support for a negative relationship between maternal cortisol and neonate birth weights. Low birth weights, resulting from high maternal cortisol, may result in low survival or low fecundity for the neonate later in life, which could result in overall population decline. We observed a negative relationship between pregnancy and bacterial killing ability, although we observed no relationship between pregnancy and haptoglobin. Study site affected bactericidal capacity and the inflammatory response, indicating the influence of external factors on immune responses, although we could not test hypotheses about the cause of those differences. This study helps advance our understanding of the plasticity and complexity of the immune system and provides insights into the how individual differences in physiology may mediate differences in fitness.

Investigating preferred coffee consumption contexts using open-ended questions

Coffee is a universally popular product, with very distinct sensory characteristics and a stimulant effect due to the caffeine content. While many people consume more than one coffee per day, it is common to have a favourite coffee during the day, associated with a specific context. Preferring a context to another can provide valuable information about the most favoured aspects of the coffee experience, that may reflect individual physiological differences that affect food/beverages perception. Open-ended questions can be useful to collect this information because they allow subjects to freely describe their experiences. This study aims at: 1) exploring consumers' preferred coffee consumption contexts and their relationship with individual physiological characteristics; 2) developing an approach to facilitate and make more efficient open-ended question analysis, using together semiotic and statistical tools.134 regular coffee consumers were characterized by the number of fungiform papillae (FP), the PROP taster status and the rate of caffeine metabolism (CMI) and were asked to describe the moment of the day in which they prefer to have coffee. The results showed that the preferred context for having coffee differed according to the physiological variables of CMI, FP and, to a less extent, PROP status. Subjects with lower CMI focussed more on the social features of the experience, while higher CMI found more rewarding the sensory properties of coffee. Individuals with lower FP number found more rewarding the product sensory characteristics than individuals with higher FP number, who were more focussed on the stimulating effect of coffee. Both PROP non tasters and supertasters tended to not prefer a context where the focus was on sensory properties (e.g. tasting) and rather preferred contexts where the focus was on the social aspects related to the coffee consumption. The study showed that open-ended questions can be useful to investigate consumer perception. In addition, combined use of semiotic and statistical tools can give valuable results and can help to optimise the text analysis procedure.

The role of dorsolateral prefrontal cortex in inhibition mechanism: A study on cognitive reflection test and similar tasks through neuromodulation

The main characteristic of the cognitive reflection test (CRT) is that it requires people to overcome a cognitive conflict. Solving this conflict requires (1) inhibitory control of prepotent but incorrect responses and (2) mental set-shifting in order to reframe the problem and reach a meaningful solution. Based on the well-known involvement of the dorsolateral prefrontal cortex (DLPFC) in inhibitory control we hypothesised that transcranial direct current stimulation (tDCS) of the DLPFC would modulate its contribution to problem-solving performance. Thirty-nine participants undergoing anodal, cathodal, or sham tDCS were asked to solve the CRT and similar mathematical problems that were structured to induce an automatic, impulsive but incorrect response. To provide a multi-dimensional picture of the processes underlying responding we assessed impulsivity traits using self-report measures and recorded physiological indices using biofeedback equipment. The results indicated that participants were more likely to provide incorrect impulsive responses after cathodal stimulation, i.e. when inhibitory control associated to the DLPFC was reduced. Baseline values of blood volume pulses predicted solution recognition, highlighting the potential role of individual physiological differences in problem solving. In conclusion, this study provides evidence supporting the role of the DLPFC in modulation of processes involved in solving CRTs and similar problems, thanks to its association to the inhibitory control mechanisms involved in suppressing impulsive responses.

Gut content analysis of Lake Michigan waterbirds in years with avian botulism type E mortality, 2010–2012

Abstract Waterbird die-offs caused by Clostridium botulinum neurotoxin type E (BoNT/E) have occurred sporadically in the Great Lakes since the late 1960s, with a recent pulse starting in the late 1990s. In recent die-offs, round gobies (Neogobius melanostomus) have been implicated as vectors for the transfer of BoNT/E to fish-eating birds due to the round goby invasion history and their importance as prey. Dreissenid mussels (Dreissena spp.) are also potentially involved in BoNT/E transmission to birds and round gobies. We examined gut contents of waterbirds collected in Lake Michigan during die-offs in 2010–2012, and the gut contents of culled, presumably BoNT/E-free double-crested cormorants (Phalacrocorax auritus). Round gobies were found in 86% of the BoNT/E-positive individuals, 84% of the BoNT/E-negative birds, and 94% of the BoNT/E-free cormorants examined. Double-crested cormorants, ring-billed gulls (Larus delewarensis), and common loons (Gavia immer) consumed larger-sized round gobies than horned and red-necked grebes (Podiceps auritus and Podiceps grisegena), white-winged scoters (Melanitta deglandi), and long-tailed ducks (Clangula hymealis). Other common prey included dreissenid mussels, terrestrial insects, and alewives (Alosa pseudoharengus). Our data emphasize the importance of round gobies and mussels in diets of Lake Michigan waterbirds and suggest they may play a role in the transfer of BoNT/E to waterbirds; however, round gobies and mussels were found in BoNT/E-positive, -negative, and -free individuals, suggesting that other factors, such as alternative trophic pathways for toxin transfer, bird migratory timing and feeding locations, prey behavior, and individual physiological differences across birds may affect the likelihood that a bird will succumb to BoNT/E intoxication.

Demystifying animal 'personality' (or not): why individual variation matters to experimental biologists.

Animal 'personality', defined as repeatable inter-individual differences in behaviour, is a concept in biology that faces intense controversy. Critics argue that the field is riddled with terminological and methodological inconsistencies and lacks a sound theoretical framework. Nevertheless, experimental biologists are increasingly studying individual differences in physiology and relating these to differences in behaviour, which can lead to fascinating insights. We encourage this trend, and in this Commentary we highlight some of the benefits of estimating variation in (and covariation among) phenotypic traits at the inter- and intra-individual levels. We focus on behaviour while drawing parallels with physiological and performance-related traits. First, we outline some of the confusion surrounding the terminology used to describe repeatable inter-individual differences in behaviour. Second, we argue that acknowledging individual behavioural differences can help researchers avoid sampling and experimental bias, increase explanatory power and, ultimately, understand how selection acts on physiological traits. Third, we summarize the latest methods to collect, analyse and present data on individual trait variation. We note that, while measuring the repeatability of phenotypic traits is informative in its own right, it is only the first step towards understanding how natural selection and genetic architecture shape intra-specific variation in complex, labile traits. Thus, understanding how and why behavioural traits evolve requires linking repeatable inter-individual behavioural differences with core aspects of physiology (e.g. neurophysiology, endocrinology, energy metabolism) and evolutionary biology (e.g. selection gradients, heritability).

Consistent individual differences in haemolymph density reflect risk propensity in a marine invertebrate.

While the literature on consistent individual differences in correlated suites of physiological and behavioural traits is steadily growing for vertebrates, invertebrates have received less attention. The few studies that do exist have measured temporary physiological states (or responses), rather than consistent individual physiological traits. Here, I explore the consistency of individual differences in physiology and behaviour of n=53 shore crabs (Carcinus maenas) by repeatedly measuring haemolymph density (HD) and the crabs' responses to a novel environment. In crustaceans, HD is directly proportional to protein concentrations, and thus indicative of physiological condition. HD was highly repeatable, and crabs showed consistent individual differences in their behavioural responses to a novel environment, thus indicating individual consistency in both physiology and behaviour. Furthermore, HD was significantly correlated with the crabs' risk propensity, i.e. individuals with higher HD spent more time near shelter. Overall, this provides the first evidence for consistency in an endogenous physiological trait in an invertebrate. The link between consistent physiology and behaviour, i.e. coping styles, analogous to those found in vertebrates, suggests metabolic and/or immunological correlates of personality which offer great potential for future studies.

Within-litter differences in personality and physiology relate to size differences among siblings in cavies

Many aspects of an animal's early life potentially contribute to long-term individual differences in physiology and behaviour. From several studies on birds and mammals it is known that the early family environment is one of the most prominent factors influencing early development. Most of these studies were conducted on highly altricial species. Here we asked whether in the highly precocial cavy (Cavia aperea) the size rank within a litter, i.e. whether an individual is born as the heaviest, the lightest or an intermediate sibling, affects personality traits directly after birth and after independence. Furthermore, we investigated whether individual states (early growth, baseline cortisol and resting metabolic rate) differ between siblings of different size ranks and assessed their relation to personality traits. Siblings of the same litter differed in personality traits as early as three days after birth. Pups born heaviest in the litter were more explorative and in general more risk-prone than their smaller siblings. Physiological state variables were tightly correlated with personality traits and also influenced by the size rank within litter, suggesting that the size relative to littermates constitutes an important factor in shaping an individual's developmental trajectory. Our data add valuable information on how personalities are shaped during early phases of life and indicate the stability of developmentally influenced behavioural and physiological traits.

The impact of individual variations in taste sensitivity on coffee perceptions and preferences

Despite a few relationships between fungiform papillae (FP) density and 6-n-propylthiouracil (PROP) taster status have been reported for sensory qualities within foods, the impact on preferences remains relatively unclear. The present study investigated responses of FP number and PROP taster groups to different bitter compounds and how these affect coffee perception, consumption and liking. Subjects (Ss) with higher FP numbers (HFP) gave higher liking ratings to coffee samples than those with lower FP numbers (LFP), but only for sweetened coffee. Moreover, HFP Ss added more sugar to the samples than LFP Ss. Significant differences between FP groups were also found for the sourness of the coffee samples, but not for bitterness and astringency. However, HFP Ss rated bitter taste stimuli as stronger than did LFP Ss. While coffee liking was unrelated to PROP status, PROP non-tasters (NTs) added more sugar to the coffee samples than did super-tasters (STs). In addition, STs rated sourness, bitterness and astringency as stronger than NTs, both in coffee and standard solutions. These results confirm that FP density and PROP status play a significant role in taste sensitivity for bitter compounds in general and also demonstrate that sugar use is partly a function of fundamental individual differences in physiology.