Individual differences in motor skills ability affect the self-regulation of heart rate

Twenty males who scored relatively high on the rotor-pursuit motor skills task (High performance group) were given seven 2-minute trials to increase heart rate and seven 2-minute trials to decrease heart rate, as were 20 males who scored relatively low on the rotor-pursuit task (Low performance group). Visual analogue feedback was not provided during the first and last acceleration and deceleration trials but was presented during all other trials. Both groups of subjects were able to decrease heart rate significantly with and without feedback. Subjects in the High performance group were able to increase heart rate significantly with feedback and could generalize this increase to a no-feedback trial following feedback trials. Subjects in the Low performance group could not increase heart rate with or without feedback. Changes in respiration rate paralleled those noted for heart rate, but changes in chin electromyographic activity generally did not parallel the heart rate results. The heart rate data are discussed in terms of motor skills theories of self-regulation of heart rate.     

Individual differences affect honest signalling in a songbird

Research in the past decade has established the existence of consistent individual differences or ‘personality’ in animals and their important role in many aspects of animal behaviour. At the same time, research on honest signalling of aggression has revealed that while some of the putative aggression signals are reliable, they are only imperfectly so. This study asks whether a significant portion of the variance in the aggression-signal regression may be explained by individual differences in signalling strategies. Using the well-studied aggressive signalling system of song sparrows (Melospiza melodia), we carried out repeated assays to measure both aggressive behaviours and aggressive signalling of territorial males. Through these assays, we found that aggressive behaviours and aggressive signalling were both highly repeatable, and moreover that aggressive behaviours in 2009–2010 predicted whether the birds would attack a taxidermic mount over a year later. Most significantly, we found that residual variation in signalling behaviours, after controlling for aggressive behaviour, was individually consistent, suggesting there may be a second personality trait determining the level of aggressive signalling. We term this potential personality trait ‘communicativeness’ and discuss these results in the context of honest signalling theories and recent findings reporting prevalence of ‘under-signalling’.     

Individual differences in boldness positively correlate with heart rate in orb-weaving spiders of genus Larinioides

Recent years have seen a dramatic increase in the number of studies devoted to consistent individual differences in behavior, termed ＂behavioral syndromes＂ or animal ＂personality＂. In particular, ecologists and evolutionary biologists alike seek to explore the functional consequences of individuals＇ personalities and explanations for their general maintenance. Understand ing the mechanistic underpinnings to personality is arguably key to a deeper understanding of their functional consequences and maintenance. In particular, consistent individual differences in metabolic rate have been proposed as a general explanation for the maintenance of consistent individual differences in boldness, aggressiveness, and activity level. In this paper we explore whether consistent individual differences in boldness are associated with heat rate, a proxy for metabolic rate, in two species of orbweaving spider： Larinioides cornutus and L. patagiatus. We first documented consistent individual differences in boldness in L. cornutus but not L. patagiatus, as estimated by individuals＇ latency to resume movement following an aversive stimulus. We also measured individuals＇ heart rate twice in a separate situation. We then tested for an association between individuals＇ boldness and their heart rate during these two events. We found that increased boldness was associated with increased heart. Thus, indi viduals that resumed movement quickly following an aversive stimulus also exhibited faster heart rates. Our studies provide fur ther evidence that consistent individual differences in key physiological attributes, like metabolic rate, might be a general mecha nism underlying consistent individual differences in behavior .     

Individual differences in odor imaging ability reflect differences in olfactory and emotional perception

We asked whether the large variability in odor imaging ability is underlain by interindividual differences in the processing of smells and emotion. Olfactory imaging ability, anhedonia level, and odor perception were measured in 40 subjects, using the Vividness of Olfactory Imagery Questionnaire (VOIQ), the Physical Anhedonia Scale, and the European Test of Olfactory Capabilities. "Good" olfactory imagers, defined primarily on the basis of the VOIQ, rated pleasant smells as more familiar and had lower anhedonia scores than "bad" olfactory imagers. Based on self-reported measures, these results suggest that, like olfactory perception, the mental imagery of smells is related to emotion and that, beyond their differences in vividness, good and bad olfactory imagers differ in their experience of emotion and long-term memory of smells.     

Individual differences and variability in the timing of motor activity during walking in insects

The uniformity of the neural physiology of an animal population is a fundamental, rarely tested assumption in most neurophysiological work. In this study, the variability of the timing between the movements of pairs of legs during free walking in cockroaches was assessed. Phases (a measure of timing) of motor bursts in muscles of legs in the American cockroach, Periplaneta americana, were calculated for insects walking straight over a flat, level surface. Student's t, Wallraff, Mann Whitney and Watson U² two-sample tests were used to compare the phases of motor bursts of the same pairs of legs in different insects. The comparisons showed that in spite of the homogeneity both of the animal population and of the conditions under which the insects walked, most of the inter-leg phases of the animals that were compared were significantly different statistically. Further testing of greater numbers of insects using analysis of variance to test for population uniformity confirmed that the insects we tested were not members of a single statistical population with respect to the timing of motor bursts of the legs during walking. We infer that this unexpectedly large variability in a population thought to be relatively homogeneous reflects subtle but biologically significant differences between animals. The possible sources of these differences and their consequences for the study of behavior and its physiological basis are discussed.     

Individual differences in subconscious motor control predicted by GABA concentration in SMA

Subliminal visual stimuli affect motor planning, but the size of such effects differs greatly between individuals. Here, we investigated whether such variation may be related to neurochemical differences between people. Cortical responsiveness is expected to be lower under the influence of more of the main inhibitory neurotransmitter, GABA. Thus, we hypothesized that, if an individual has more GABA in the supplementary motor area (SMA)--a region previously associated with automatic motor control--this would result in smaller subliminal effects. We measured the reversed masked prime--or negative compatibility--effect, and found that it correlated strongly with GABA concentration, measured with magnetic resonance spectroscopy. This occurred specifically in the SMA region, and not in other regions from which spectroscopy measurements were taken. We replicated these results in an independent cohort: more GABA in the SMA region is reliably associated with smaller effect size. These findings suggest that, across individuals, the responsiveness of subconscious motor mechanisms is related to GABA concentration in the SMA.     

Individual differences in the ability to recognise facial identity are associated with social anxiety

Previous research has been concerned with the relationship between social anxiety and the recognition of face expression but the question of whether there is a relationship between social anxiety and the recognition of face identity has been neglected. Here, we report the first evidence that social anxiety is associated with recognition of face identity, across the population range of individual differences in recognition abilities. Results showed poorer face identity recognition (on the Cambridge Face Memory Test) was correlated with a small but significant increase in social anxiety (Social Interaction Anxiety Scale) but not general anxiety (State-Trait Anxiety Inventory). The correlation was also independent of general visual memory (Cambridge Car Memory Test) and IQ. Theoretically, the correlation could arise because correct identification of people, typically achieved via faces, is important for successful social interactions, extending evidence that individuals with clinical-level deficits in face identity recognition (prosopagnosia) often report social stress due to their inability to recognise others. Equally, the relationship could arise if social anxiety causes reduced exposure or attention to people's faces, and thus to poor development of face recognition mechanisms.     

Individual differences in women''s facial preferences as a function of digit ratio and mental rotation ability

The second-to-fourth digit ratio (2D:4D) and mental rotation (MR) ability are sexually dimorphic traits that appear early in development and have been correlated with exposure to prenatal androgens (Grimshaw, Sitarenios, & Finegan, 1995; Lutchmaya, Baron-Cohen, Raggatt, Knickmeyer, & Manning, 2004). The current study examined how 2D:4D and MR differences among women of European descent (N=41) were related to their (a) preferences for male faces: attractive (ATM), short-term (STM), and long-term mate (LTM), and (b) psychological femininity and masculinity, as measured by the Bem Sex-Role Inventory (BSRI) (Bem, 1981). To examine potential changes in facial preferences over their menstrual cycle, participants' preferences were measured during two experimental sessions separated by 2 weeks. The results indicated that (a) femininity scores decreased with decreasing 2D:4D, (b) masculinity scores increased with faster MR, (c) women preferred a more masculine male face for an STM than for an LTM, and (d) preference changes over the menstrual cycle varied systematically with 2D:4D. When compared with women with high 2D:4D ratios, low 2D:4D women (e) preferred a more masculine LTM, (f) recalled less parental bonding, (g) had shorter intimate relationships, and (h) reported more menstrual irregularity. The results are interpreted as support for an interactive hormonal theory of physical attraction.     

Individual differences in emotion processing

Recent functional brain imaging studies of the neurobiology of emotion have investigated how individual differences among subjects modulate neural responses during emotion processing. Differences in personality, dispositional affect, biological sex, and genotype can all substantially modulate the neural bases of emotion processing in prefrontal, limbic, and other brain regions, across a variety of domains including emotional reactions, emotional memory, and emotion perception. Analysis of individual differences provides a new window into the neurobiology of emotion processing that complements traditional approaches.     

Formation of lateralized motor skills in rats

Adult Wistar rats were trained to get food with a forepaw from a narrow tube under conditions of free choice of a limb. It was shown that the presence or absence of limb preference determined by preliminary short-run testing far from always defines the character and extent of lateralization formed in the process of training. It was also found that reaching the maximal extent of lateralization requires, on average, more extended period of training for the animals, which finally constituted the group of right-handers, than for the rats finally classified as left-handers.     

Quantitative estimation of connection of the heart rate rhythm with motor activity in rat fetuses

In rat fetuses over E17-20 with preserved placental circulation with use of mathematical analysis there were revealed value and character of connections of slow wave oscillations of the heart rhythm with motor activity for 30 min of observation. In the software PowerGraph 3.3.8, normalization and filtration of the studied signals were performed in three frequency diapasons: D1-0.02–0.2 Hz (5–50 s), D2-0.0083-0.02 Hz (50 s-2 min), and D3-0.0017–0.0083 Hz (2–10 min). The EMG curves filtrated by diapasons or piezograms were compared with periodograms in the corresponding diapasons of the heart rhythm variations. In the software “Origin 8.0”, quantitative estimation of the degree of intersystemic interrelations for each frequency diapason was performed by Pearson correlation of coefficient, by the correlation connection value, and by the time shift of maximum of cross-correlation function. It has been established that in the frequency D1, regardless of age, the connection of heart rhythm oscillations with motor activity is expressed weakly. In the frequency diapason D2, the connection in most cases is located in the zone of weak and moderate correlations. In the multiminute diapason (D3), the connection is more pronounced. The number of animals that have a significant value of the correlation connection rises. The fetal motor activity fires in the decasecond diapason in all age groups are accompanied by short-time decelerations of the heart rhythms. In the minute diapason, there is observed a transition from positive connections in E17 and E18 to the negative ones in E19-20. Results of the study are considered in association with age-related changes of ratios of positive and negative oscillations of the heart rhythm change depending on the character of motor activity.     

Individual differences in subjective circadian flexibility

The aim of this study was to evaluate individual differences in the subjective flexibility of the circadian system in a community sample, with respect to age, gender, chronotype, and sleepiness perceptions. An online questionnaire containing the Circadian Type Inventory, the Composite Scale of Morningness, the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale was administered. In addition, participants performed a visuo-verbal judgment task to determine time-of-day variations in estimated sleepiness. We analyzed data of 752 participants, aged between 18 and 83 years, who reported good sleep quality, no sleep disturbances, no excessive daytime sleepiness, and no engagement in shiftwork. Our results suggest gender- and chronotype-related differences in the subjective flexibility of the circadian system. Subjective circadian flexibility was higher in men in comparison with women and was positively related to evening preference. Age was not associated with flexibility scores. Additionally, the subjective flexibility of the circadian system had an influence on estimated sleepiness profiles: individuals with a high flexibility displayed lower sleepiness estimations during the biological night in comparison to individuals with a low flexibility. These findings suggests that, next to known chronotype and other dispositional differences, subjective circadian flexibility should be taken into account when evaluating tolerance to activities associated with nighttime functioning (e.g. night shifts).     

Individual differences in respiratory sinus arrhythmia

To investigate the interindividual differences in respiratory sinus arrhythmia (RSA), recordings of ventilation and electrocardiogram were obtained from 12 healthy subjects for five imposed breathing periods (T(TOT)) surrounding each individual's spontaneous breathing period. In addition to the spectral analysis of the R-R interval signal at each breathing period, RSA characteristics were quantified by using a breath-by-breath analysis where a sinusoid was fitted to the changes in instantaneous heart rate in each breath. The amplitude and phase (or delay = phase x T(TOT)) of this sinusoid were taken as the RSA characteristics for each breath. It was found that for each subject the RSA amplitude-T(TOT) relationship was linear, whereas the delay-T(TOT) relationship was parabolic. However, the parameters of these relationships differed between individuals. Linear correlation between the slopes of RSA amplitude versus T(TOT) regression lines and 1) mean breathing period and 2) mean R-R interval during spontaneous breathing were calculated. Only the correlation coefficient with breathing period was significantly different from zero, indicating that the longer the spontaneous breathing period the lesser the increase in RSA amplitude with increasing breathing period. Similarly, only the correlation coefficient between the curvature of the RSA delay-T(TOT) parabola and mean breathing period was significantly different from zero; the longer the spontaneous breathing period the larger the curvature of RSA delay. These results suggest that the changes in RSA characteristics induced by changing the breathing period may be explained partly by the spontaneous breathing period of each individual. Furthermore, a transfer function analysis performed on these data suggested interindividual differences in the autonomic modulation of the heart rate.     

Individual differences in aggressiveness of adelie penguins

The number of pecks per minute given by individual Adelie penguins to an artificial model is used as a measure of aggressiveness. Penguins without eggs or chicks are less aggressive than thoes with eggs or chicks. Aggressiveness increases after egg-laying, and reaches a peak at about chick hatching. Prior to egg-laying, males are more aggressive towards the model than females, but after egg-laying there is no difference between them (on average). Most penguins with above average aggressiveness are located at territories in the centre of a colony, whereas those with below average aggressiveness tend to occur at the periphery. Penguins with high aggressiveness also have a higher breeding success than less aggressive ones.     

Individual differences in reinforcing effects of song

Six out of eight first-year male chaffinches showed some reinforcing effect of song, by perching on a particular perch and remaining on it in order to keep song playing. Since birds could show reinforcing effects by changing frequency, duration, or both, of operant perching, five different indices of reinforcement were considered. Correlations between all but one pair of indices were low, and no index had higher values than any other. For some individuals, one index was high, and for others another. Thus the need for recognizing, rather than ignoring, individual differences is illustrated.     

Factors that affect the folding ability of proteins

The folding ability of a heteropolymer model for proteins subject to Monte Carlo dynamics on a simple cubic lattice is shown to be strongly correlated with the stability of the native state. We consider a number of estimates of the stability that can be determined without simulation, including the energy gap between the native state and the structurally dissimilar part of the spectrum (Z score) and, for sequences with fully compact native states, the gap in energy between the native and first excited fully compact states. These estimates are found to be more robust predictors of folding ability than a parameter sigma that requires simulation for its evaluation: sigma = 1 - Tf/Ttheta, where Tf is the temperature at which the fluctuation of an order parameter is at its maximum and Ttheta is the temperature at which the specific heat is at its maximum. We show that the interpretation of Ttheta as the collapse transition temperature is not correct in general and that the correlation between sigma and the folding ability arises from the fact that sigma is related to the energy gap (Z score).     

Individual differences in PCA response in the guinea pig

Experiments were carried out to determine the cause of individual differences in the passive cutaneous anaphylaxis (PCA) response in guinea pigs. The intensity of 4-h homologous PCA produced by anti-penicillin G serum was not markedly different among eight reactive sites on the back of a specified animal, whereas considerable individual differences were observed in the PCA response, even at a specified reactive site. PCA was significantly inhibited by an antihistaminic agent, promethazine, and the tissue histamine content was significantly reduced after PCA, suggesting histamine release as a mediator. The intensity of PCA in individual animals was highly correlated with that of the histamine-induced cutaneous reaction elicited at a site adjoining the PCA but was unrelated to skin histamine content. These results suggest that the difference in susceptibility to histamine has a considerable effect on individual differences in the PCA response in guinea pigs.     

Individual quantitative differences in the structure of the human hippocampus

The volume of the hippocampal grey substance (Corpus Ammoni--CA) and that of the denticulated plate (Fasciculus dentatus--FD) have been studied in mature persons of various sex and age (17 subjects, 22 cerebral hemispheres) under cytoarchitectonic control defining the borders of the cerebral formations mentioned. Certain quantitative and spatial differences of CA and FD have been revealed in some subjects. Especially great differences are noted between more seldom occurring extreme individual variants, their difference being as great as three times. The differences revealed are demonstrated to be independent on the brain mass of the human beings studied. The observation performed causes to revise the competency of the principle concerning a constant proportional dependence between the reference points on the cerebral surface and the internal cerebral structures. These data are used in neurosurgery when surgical interventions are performed on brains with different dimensions. A suggestion is made that the individual volumetric differences revealed in the hippocamp of various persons are defined by its functional specificity.