Adaptive Behavioral Changes Research Articles

Behavioural effects of temperature on ectothermic animals: unifying thermal physiology and behavioural plasticity.

Temperature imposes significant constraints on ectothermic animals, and these organisms have evolved numerous adaptations to respond to these constraints. While the impacts of temperature on the physiology of ectotherms have been extensively studied, there are currently no frameworks available that outline the multiple and often simultaneous pathways by which temperature can affect behaviour. Drawing from the literature on insects, we propose a unified framework that should apply to all ectothermic animals, generalizing temperature's behavioural effects into: (1) kinetic effects, resulting from temperature's bottom-up constraining influence on metabolism and neurophysiology over a range of timescales (from short to long term), and (2) integrated effects, where the top-down integration of thermal information intentionally initiates or modifies a behaviour (behavioural thermoregulation, thermal orientation, thermosensory behavioural adjustments). We discuss the difficulty in distinguishing adaptive behavioural changes from constraints when observing animals' behavioural responses to temperature. We then propose two complementary approaches to distinguish adaptations from constraints, and categorize behaviours according to our framework: (i) 'kinetic null modelling' of temperature's effects on behaviour; and (ii) behavioural ecology experiments using temperature-insensitive mutants. Our framework should help to guide future research on the complex relationship between temperature and behaviour in ectothermic animals.

Incorporating Development Into Evolutionary Psychology

Developmental thinking is gradually becoming integrated within mainstream evolutionary psychology. This is most apparent with respect to the role of parenting, with proponents of life history theory arguing that cognitive and behavioral plasticity early in life permits children to select different life history strategies, with such strategies being adaptive solutions to different fitness trade-offs. I argue that adaptations develop and are based on the highly plastic nature of infants’ and children’s behavior/cognition/brains. The concept of evolved probabilistic cognitive mechanisms is introduced, defined as information processing mechanisms evolved to solve recurrent problems faced by ancestral populations that are expressed in a probabilistic fashion in each individual in a generation and are based on the continuous and bidirectional interaction over time at all levels of organization, from the genetic through the cultural. Early perceptual/cognitive biases result in behavior that, when occurring in a species-typical environment, produce continuous adaptive changes in behavior (and cognition), yielding adaptive outcomes. Examples from social learning and tool use are provided, illustrating the development of adaptations via evolved probabilistic cognitive mechanisms. The integration of developmental concepts into mainstream evolutionary psychology (and evolutionary concepts into mainstream developmental psychology) will provide a clearer picture of what it means to be human.

Repeated daily restraint stress induces adaptive behavioural changes in both adult and juvenile mice

Chronic stress is known to be a risk factor for the development of depression and anxiety, disorders which often begin during adolescence. Restraint stress is a commonly used stressor in adult rodents, however the effects of repeated restraint stress in juvenile mice have not been well characterised. Here we have shown for the first time the behavioural and hormonal effects of repeated restraint stress in both adult and juvenile BALB/c and C57BL/6 mice. Repeated daily restraint stress (2h/day for 3, 7 or 14days) provoked a robust physiological response evident as increased corticosterone levels and decreased body weight after 14days. However, habituation of the stress-response was evident during repeated exposure to the stressor in both adult and juvenile mice. The behavioural changes seen in response to repeated restraint stress were complex. In juvenile mice, repeated restraint stress evoked an increase in exploratory behaviours in the elevated plus maze, a decrease in time spent immobile in the forced swim test and a decrease in sucrose preference. In adult mice fewer behavioural changes were seen. Interestingly BALB/c and C57BL/6 mice showed qualitatively similar response to 3days repeated restraint stress. The behavioural changes we observed, as a result of prior stress exposure, may represent an adaptive stress-coping response or resilience. Both the hormonal and behavioural effects of stress were more pronounced in juvenile mice than in adults. This wider range of behavioural responses seen in juvenile mice might reflect a greater ability to engage in adaptive stress-coping strategies that likely have beneficial effects evident in future stress challenges.

Lasting Adaptations in Social Behavior Produced by Social Disruption and Inhibition of Adult Neurogenesis.

Research on social instability has focused on its detrimental consequences, but most people are resilient and respond by invoking various coping strategies. To investigate cellular processes underlying such strategies, a dominance hierarchy of rats was formed and then destabilized. Regardless of social position, rats from disrupted hierarchies had fewer new neurons in the hippocampus compared with rats from control cages and those from stable hierarchies. Social disruption produced a preference for familiar over novel conspecifics, a change that did not involve global memory impairments or increased anxiety. Using the neuropeptide oxytocin as a tool to increase neurogenesis in the hippocampus of disrupted rats restored preference for novel conspecifics to predisruption levels. Conversely, reducing the number of new neurons by limited inhibition of adult neurogenesis in naive transgenic GFAP-thymidine kinase rats resulted in social behavior similar to disrupted rats. Together, these results provide novel mechanistic evidence that social disruption shapes behavior in a potentially adaptive way, possibly by reducing adult neurogenesis in the hippocampus. To investigate cellular processes underlying adaptation to social instability, a dominance hierarchy of rats was formed and then destabilized. Regardless of social position, rats from disrupted hierarchies had fewer new neurons in the hippocampus compared with rats from control cages and those from stable hierarchies. Unexpectedly, these changes were accompanied by changes in social strategies without evidence of impairments in cognition or anxiety regulation. Restoring adult neurogenesis in disrupted rats using oxytocin and conditionally suppressing the production of new neurons in socially naive GFAP-thymidine kinase rats showed that loss of 6-week-old neurons may be responsible for adaptive changes in social behavior.

Abstract 381: Chemogenetic Activation of Satellite Glial Gq-GPCR Signaling Enhances Cardiovascular Function in vivo

The autonomic nervous system (ANS) exerts profound regulatory influence over cardiovascular physiology. The integrated network among autonomic nuclei in the central nervous system (CNS), as well as ganglionic innervation in the peripheral nervous system (PNS) are essential for homeostasis and for coordinating adaptive changes in physiology and behavior. In addition to neurons, the ANS contains large numbers of Glial Fibrillary Acidic Protein (GFAP) - expressing cells (GFAP + glial cells), which serve many functions in assisting neuronal network activity in both the CNS and the PNS. The present study explores the active role of GFAP + glial cells in regulating cardiovascular function in vivo . Using DREADD technology, we selectively activate Gq-GPCR signaling in satellite glial cells (SGCs) within sympathetic ganglia, which led to fast-acting, long-lasting increases in cardiac function and blood pressure in vivo . In addition, ganglionic SGCs likely increase postganglionic neuronal firing and subsequent norepinephrine release via a “local stimulatory effect“ on postganglionic neurons. Ongoing studies ex vivo using superior cervical ganglia cultures focus on identifying the mechanism underlying the interaction between sympathetic SGCs and postganglionic neurons.

Repeated Inflammation-Related Pain Syndrome in Neonatal Male Rats Alters Adaptive Behavior during the Adolescent Period of Development

We report here our studies on the effects of repeated inflammation-related pain syndrome in in neonatal male rat pups aged one and two days on the characteristics of adaptive behavior in the formalin test, elevated plus maze test, and forced swimming test, as well as in the Morris water maze, when the animals reached the age of 25 days. These experiments yielded new data providing evidence of increases in the functional activity of the tonic nociceptive system, increases in the tendency to depression-like behavior, and deterioration of spatial learning. Of particular importance is the fact that short-lived (60 min) repeated maternal deprivation of neonatal rats (a stressor) without the pain factor induced by inflammatory foci led to changes in adaptive behavior in 25-day-old animals. Assessment of pain responses organized at different levels of the central nervous system in the formalin test allowed the sequelae of the early effects of pain and stress on the behavioral measures studied to be discriminated.

Eating in mice with gastric bypass surgery causes exaggerated activation of brainstem anorexia circuit.

Background/ObjectiveObesity and metabolic diseases are at an alarming level globally and increasingly affect children and adolescents. Gastric bypass and other bariatric surgeries have proven remarkably successful and are increasingly performed worldwide. Reduced desire to eat and changes in eating behavior and food choice account for most of the initial weight loss and diabetes remission after surgery, but the underlying mechanisms of altered gut-brain communication are unknown.Subjects/MethodsTo explore the potential involvement of a powerful brainstem anorexia pathway centered around the lateral parabrachial nucleus (lPBN) we measured meal-induced neuronal activation by means of c-Fos immunohistochemistry in a new high-fat diet-induced obese mouse model of Roux-en-Y gastric bypass (RYGB) at 10 and 40 days after RYGB or sham surgery.ResultsVoluntary ingestion of a meal 10 days after RYGB, but not after sham surgery, strongly and selectively activates calcitonin gene-related peptide neurons in the external lPBN as well as neurons in the nucleus tractus solitaries, area postrema, and medial amygdala. At 40 days after surgery, meal-induced activation in all these areas was greatly diminished and did not reach statistical significance.ConclusionsThe neural activation pattern and dynamics suggest a role of the brainstem anorexia pathway in the early effects of RYGB on meal size and food intake that may lead to adaptive neural and behavioral changes involved in the control of food intake and body weight at a lower level. However, selective inhibition of this pathway will be required for a more causal implication.

Effect of Embelin Against Lipopolysaccharide‐induced Sickness Behaviour in Mice

Sickness behaviour is a coordinated set of adaptive behavioural changes that develop in ill individuals during the course of an infection. It is relevant to understanding depression and some aspects of the suffering that in cancer. Embelin has been reported to possess antiinflammatory, neuroprotective and anxiolytic assets and has been shown to inhibit nuclear factor κB pathway and cytokine production. The present study was undertaken to investigate the effect of embelin isolated from Embelia ribes Burm in lipopolysaccharide (LPS)-induced sickness behaviour in mice. Adult male Swiss albino mice were pre-treated with embelin (10 and 20 mg/kg, p.o.) or dexamethasone (1 mg/kg, i.p.) for 3 days and then challenged with LPS (400 µg/kg, i.p.). At different time intervals of post-LPS challenge, sickness behaviour was evaluated in the animals by battery of behavioural tests (plus maze, open field, light-dark box, forced swim, social behaviour assessment, sucrose preference and food and water intake). Levels of oxidative stress makers (reduced glutathione and lipid peroxidation) in mice brain were also analysed. LPS induced behavioural alterations, anhedonia and anorexia, in mice. Pre-treatment with embelin attenuated behavioural changes induced by LPS. In addition, embelin prevented anhedonia, anorexia and ameliorated brain oxidative stress markers. The experimental outcomes of the present study demonstrated protective effect of embelin in LPS-induced sickness behaviour in mice. Copyright © 2016 John Wiley & Sons, Ltd.

Fish lack the brains and the psychology for pain

Fish lack the brains and the psychology for pain

Pulmonary Rehabilitation and Physical Activity in Patients with Chronic Obstructive Pulmonary Disease.

Physical inactivity is common in patients with chronic obstructive pulmonary disease (COPD) compared with age-matched healthy individuals or patients with other chronic diseases. Physical inactivity independently predicts poor outcomes across several aspects of this disease, but it is (at least in principle) treatable in patients with COPD. Pulmonary rehabilitation has arguably the greatest positive effect of any current therapy on exercise capacity in COPD; as such, gains in this area should facilitate increases in physical activity. Furthermore, because pulmonary rehabilitation also emphasizes behavior change through collaborative self-management, it may aid in the translation of increased exercise capacity to greater participation in activities involving physical activity. Both increased exercise capacity and adaptive behavior change are necessary to achieve significant and lasting increases in physical activity in patients with COPD. Unfortunately, it is readily assumed that this translation occurs naturally. This concise clinical review will focus on the effects of a comprehensive pulmonary rehabilitation program on physical activity in patients with COPD. Changing physical activity behavior in patients with COPD needs an interdisciplinary approach, bringing together respiratory medicine, rehabilitation sciences, social sciences, and behavioral sciences.

Longitudinal Examination of Adaptive Behavior in Autism Spectrum Disorders: Influence of Executive Function.

This study characterizes longitudinal change in adaptive behavior in 64 children and adolescents with autism spectrum disorder (ASD) without intellectual disability evaluated on multiple occasions, and examines whether prior estimate of executive function (EF) problems predicts future adaptive behavior scores. Compared to standardized estimates for their developmental stage, adaptive behavior in most participants was impaired and did not improve over time. Prior EF predicted later adaptive behavior in daily living skills and socialization domains after controlling for age and IQ. Self-monitoring behaviors robustly predicted later adaptive behavior in all domains (d = 0.60-0.94). Results support targeting treatment of adaptive skills in ASD, as well as the importance of assessing for EF problems that may contribute to adaptive behavior difficulties.

Developing adaptations

The concept of adaptation is ubiquitous in psychology and plays a central role in evolutionary psychology. In this article I provide a different way of thinking about adaptations from an evolutionary developmental psychological perspective, more in line with the theorizing of developmental systems perspective than with mainstream evolutionary psychology. Adaptations develop and are based on the highly plastic nature of infants and children's behavior/cognition/brains. The concept of evolved probabilistic cognitive mechanisms is introduced, defined as information-processing mechanisms evolved to solve recurrent problems faced by ancestral populations that are expressed in a probabilistic fashion in each individual in a generation, based on the continuous and bidirectional interaction over time at all levels of organization, from the genetic through the cultural. Early perceptual/cognitive/affective biases result in behavior that, when occurring in a species-typical (expectant) environment, produce continuous adaptive changes in behavior (and cognition), yielding stable (and adaptive) outcomes. Examples from two domains, the development of face processing in infancy and prepared fears, are provided illustrating the development of adaptations via evolved probabilistic cognitive mechanisms.

Social Transitions Cause Rapid Behavioral and Neuroendocrine Changes.

In species that form dominance hierarchies, there are often opportunities for low-ranking individuals to challenge high-ranking ones, resulting in a rise or fall in social rank. How does an animal rapidly detect, process, and then respond to these social transitions? This article explores and summarizes how these social transitions can rapidly (within 24 h) impact an individual's behavior, physiology, and brain, using the African cichlid fish, Astatotilapia burtoni, as a model. Male A. burtoni form hierarchies in which a few brightly-colored dominant males defend territories and spawn with females, while the remaining males are subordinate, more drab-colored, do not hold a territory, and have minimal opportunities for reproduction. These social phenotypes are plastic and reversible, meaning that individual males may switch between dominant and subordinate status multiple times within a lifetime. When the social environment is manipulated to create males that either ascend (subordinate to dominant) or descend (dominant to subordinate) in rank, there are rapid changes in behavior, circulating hormones, and levels of gene expression in the brain that reflect the direction of transition. For example, within minutes, males ascending in status show bright coloration, a distinct eye-bar, increased dominance behaviors, activation of brain nuclei in the social behavior network, and higher levels of sex steroids in the plasma. Ascending males also show rapid changes in levels of neuropeptide and steroid receptors in the brain, as well as in the pituitary and testes. To further examine hormone-behavior relationships in this species during rapid social ascent, the present study also measured levels of testosterone, 11-ketotestosterone, estradiol, progestins, and cortisol in the plasma during the first week of social ascent and tested for correlations with behavior. Plasma levels of all steroids were rapidly increased at 30 min after social ascent, but were not correlated with behavior during the initial rise in rank, suggesting that behavior is dissociated from endocrine status. These changes during social ascent are then compared with our current knowledge about males descending in rank, who rapidly show faded coloration, decreased dominance behaviors, increased subordinate behaviors, and higher circulating levels of cortisol. Collectively, this work highlights how the perception of similar social cues that are opposite in value are rapidly translated into adaptive behavioral and neuroendocrine changes that promote survival and reproductive fitness. Finally, future directions are proposed to better understand the mechanisms that govern these rapid changes in social position.

Effects of human Wharton’s jelly-derived mesenchymal stem cells and Interleukin-10 on behavioural responses of rats with experimental allergic encephalomyelitis

On the rat model of experimental allergic encephalomyelitis (EAE), as analogue of multiple sclerosis of human, we studied the effect of Wharton’s jelly-derived mesenchymal stem cells and interleukin-10 on the functional parameters of the CNS.Materials and methods. EAE was induced with spinal cord homogenate of rats with complete Freund’s adjuvant. MSCs were isolated by the explants technique from Wharton’s jelly of the human umbilical cord and cultured up to two passages. Recombinant IL-10 was administered intravenously on the day 10 after induction of EAE and subocipitally on the day 17 at a dose of 0.2 mg per animal. Cell transplantation performed subocipitally on the day 17 at a dose of 106 cells per animal. Behavioral reactions studied in the “open field” test three times: on the day 12, 15 and 24 after the induction of EAE.Results. Induced EAE results in significant changes in adaptive behavior of rats on the 12th day as suppression of orienting-exploratory and activation of emotional activity. The application of MSCs and IL-10 has normalized the rates of cognitive activities (orienting-exploratory activity) and emotional sphere (the level of fear, anxiety).Conclusion. Combined treatment of induced EAE in rats with interleukin-10 and human Wharton’s jelly-derived mesenchymal stem cells is effective at correction of behavioral responses of animals.

Executive Function and Adaptive Behavior in Muenke Syndrome

To investigate executive function and adaptive behavior in individuals with Muenke syndrome using validated instruments with a normative population and unaffected siblings as controls. Participants in this cross-sectional study included individuals with Muenke syndrome (P250R mutation in FGFR3) and their mutation-negative siblings. Participants completed validated assessments of executive functioning (Behavior Rating Inventory of Executive Function [BRIEF]) and adaptive behavior skills (Adaptive Behavior Assessment System, Second Edition [ABAS-II]). Forty-four with a positive FGFR3 mutation, median age 9 years, range 7 months to 52 years were enrolled. In addition, 10 unaffected siblings served as controls (5 males, 5 females; median age, 13 years; range, 3-18 years). For the General Executive Composite scale of the BRIEF, 32.1% of the cohort had scores greater than +1.5 SD, signifying potential clinical significance. For the General Adaptive Composite of the ABAS-II, 28.2% of affected individuals scored in the 3rd-8th percentile of the normative population, and 56.4% were below the average category (<25th percentile). Multiple regression analysis did not identify craniosynostosis as a predictor of BRIEF (P = .70) or ABAS-II scores (P = .70). In the sibling pair analysis, affected siblings performed significantly poorer on the BRIEF General Executive Composite and the ABAS-II General Adaptive Composite. Individuals with Muenke syndrome are at an increased risk for developing adaptive and executive function behavioral changes compared with a normative population and unaffected siblings.

Prism adaptation and spatial neglect: the need for dose-finding studies.

Spatial neglect is a devastating disorder in 50–70% of right-brain stroke survivors, who have problems attending to, or making movements towards, left-sided stimuli, and experience a high risk of chronic dependence. Prism adaptation is a promising treatment for neglect that involves brief, daily visuo-motor training sessions while wearing optical prisms. Its benefits extend to functional behaviors such as dressing, with effects lasting 6 months or longer. Because one to two sessions of prism adaptation induce adaptive changes in both spatial-motor behavior (Fortis et al., 2011) and brain function (Saj et al., 2013), it is possible stroke patients may benefit from treatment periods shorter than the standard, intensive protocol of ten sessions over two weeks—a protocol that is impractical for either US inpatient or outpatient rehabilitation. Demonstrating the effectiveness of a lower dose will maximize the availability of neglect treatment. We present preliminary data suggesting that four to six sessions of prism treatment may induce a large treatment effect, maintained three to four weeks post-treatment. We call for a systematic, randomized clinical trial to establish the minimal effective dose suitable for stroke intervention.

Zinc prevents sickness behavior induced by lipopolysaccharides after a stress challenge in rats.

Sickness behavior is considered part of the specific beneficial adaptive behavioral and neuroimmune changes that occur in individuals in response to infectious/inflammatory processes. However, in dangerous and stressful situations, sickness behavior should be momentarily abrogated to prioritize survival behaviors, such as fight or flight. Taking this assumption into account, we experimentally induced sickness behavior in rats using lipopolysaccharides (LPS), an endotoxin that mimics infection by gram-negative bacteria, and then exposed these rats to a restraint stress challenge. Zinc has been shown to play a regulatory role in the immune and nervous systems. Therefore, the objective of this study was to examine the effects of zinc treatment on the sickness response of stress-challenged rats. We evaluated 22-kHz ultrasonic vocalizations, open-field behavior, tumor necrosis factor α (TNF-α), corticosterone, and brain-derived neurotrophic factor (BDNF) plasma levels. LPS administration induced sickness behavior in rats compared to controls, i.e., decreases in the distance traveled, average velocity, rearing frequency, self-grooming, and number of vocalizations, as well as an increase in the plasma levels of TNF-α, compared with controls after a stressor challenge. LPS also decreased BDNF expression but did not influence anxiety parameters. Zinc treatment was able to prevent sickness behavior in LPS-exposed rats after the stress challenge, restoring exploratory/motor behaviors, communication, and TNF-α levels similar to those of the control group. Thus, zinc treatment appears to be beneficial for sick animals when they are facing risky/stressful situations.

Orientation-Dependent Changes in Single Motor Neuron Activity during Adaptive Soft-Bodied Locomotion

Recent major advances in understanding the organizational principles underlying motor control have focused on a small number of animal species with stiff articulated skeletons. These model systems have the advantage of easily quantifiable mechanics, but the neural codes underlying different movements are difficult to characterize because they typically involve a large population of neurons controlling each muscle. As a result, studying how neural codes drive adaptive changes in behavior is extremely challenging. This problem is highly simplified in the tobacco hawkmoth Manduca sexta, which, in its larval stage (caterpillar), is predominantly soft-bodied. Since each M. sexta muscle is innervated by one, occasionally two, excitatory motor neurons, the electrical activity generated by each muscle can be mapped to individual motor neurons. In the present study, muscle activation patterns were converted into motor neuron frequency patterns by identifying single excitatory junction potentials within recorded electromyographic traces. This conversion was carried out with single motor neuron resolution thanks to the high signal selectivity of newly developed flexible microelectrode arrays, which were specifically designed to record from M. sexta muscles. It was discovered that the timing of motor neuron activity and gait kinematics depend on the orientation of the plane of motion during locomotion. We report that, during climbing, the motor neurons monitored in the present study shift their activity to correlate with movements in the animal's more anterior segments. This orientation-dependent shift in motor activity is in agreement with the expected shift in the propulsive forces required for climbing. Our results suggest that, contrary to what has been previously hypothesized, M.sexta uses central command timing for adaptive load compensation.

Long-term changes in adaptive behavior of rats after inflammatory pain stimulation during neonatal development

This study is devoted to the investigation of the functional activity of the tonic nociceptive system using the formalin test. We also studied the anxiety level indices, proneness to depression-like behavior and spatial learning in adolescent male rats exposed in the neonatal development to repeated pain stimulation induced by peripheral inflammation. The following groups of 25-day-old rats were used being exposed at the age of 7 and 8 days to: (1) pain stimulation by formalin injection with maternal deprivation for 1 h (FD), (2) same formalin-induced pain stimulation without maternal deprivation (FWD), (3) physiological saline injection with maternal deprivation for 1 h (PD), (4) physiological saline injection without maternal deprivation (PWD) and (5) no stimulation (intact rats). Our findings indicate that pain induced in 7–8-day-old rat pups by formalin injection into the hind leg plantar pad manifests itself at adolescence (25 days) in an inflammatory pain response enhancement under the same pain stimulation as in the formalin test, adaptive behavior disorder in the forced swim test, and spatial learning disability. Also of particular importance is our observation that short-term repeated maternal deprivation of the 7–8-day-old rat pups in the absence of inflammatory pain increases the depression-like behavior proneness index. Thus, the repeated inflammatory pain stimulation during the neonatal development brings about significant changes in the studied types of adaptive behavior as well as in spatial learning in adolescent rats.

Long-term personality changes and predictive adaptive responses after depressive episodes

An external or internal “predictive adaptive response” (PAR) can be defined as an adaptive change in long-term behavior or development due to an environmental exposure that triggers it. A PAR can lead to differential development among initially similar individuals, and increase evolutionary fitness. Despite many theories and empirical observations of PAR-like changes in depressive tendencies, clear empirical findings on human personality changes following depressive symptoms are lacking, possibly because these changes take a long time to develop and most follow up studies have been short. Here we show that in sufficiently long (5- and 15-year) clinical and general-population follow ups, increases can be observed in the Temperament and Character Inventory's personality trait harm avoidance as a function of temporally accumulating major depressive episodes (132 depression patients from Vantaa Depression Study) and depressive symptoms (3105 participants from Young Finns general-population sample). Personality changes did not occur in the other six personality traits of the inventory, but did in a highly similar neuroticism trait from another inventory. Even when controlling for concurrent changes in depressive symptoms from the baseline to the endpoint, depressive symptoms that occurred during the follow-up period associated with harm-avoidance changes, rendering individuals more fearful and anticipating harm. This study provides consistent, specific, and plausible dose–response and temporal gradients between accumulated depressive episodes and personality change. Effect sizes were between small to moderate, though. Altogether, the findings support the feasibility of using existing systems of personality assessment (i.e., self-report questionnaires) to study PARs, despite the multiplicity of the systems.