Stress e grooming: la stagione degli amori in Lemur catta (Berenty, Madagascar, S 25.00° E 46.30°)

Lemur catta, appartenente alla famiglia dei Lemuridae, è una specie di proscimmia diurna endemica del Sud e del Sud-ovest del Madagascar, caratterizzata da un sistema sociale di tipo multi-male/multi-female, regolato da precise e strette relazioni di dominanza (Jolly,1966). Fin dagli anni ’70, numerosi studi hanno messo in luce una spiccata stagionalità di questa specie, non solo dal punto di vista fisiologico, ma anche comportamentale. Il ciclo riproduttivo strettamente stagionale di Lemur catta prevede che gli accoppiamenti si concentrino all’interno della stagione secca, durante la quale le risorse alimentari scarseggiano (Jolly, 1966; Lack, 1968; Petter-Rousseaux, 1968). Lemur catta, quindi, durante la stagione degli amori, deve soddisfare un’elevata richiesta energetica a fronte di una ridotta disponibilità di risorse. La dominanza femminile, le aggressioni mirate (Jolly, 1984; Pereira, 1995) e i cambiamenti stagionali nei livelli di aggressione (Sauther, 1993) sembrano essere possibili adattamenti alle difficoltà cui i lemuri devono far fronte durante la stagione secca. Per le specie sociali, come Lemur catta, le interazioni agonistiche e aggressive possono essere motivo di stress (Wingfield et al., 1991; Salposky, 1992b) e il rango di dominanza può influire sui livelli di stress fisico e sociale degli individui del gruppo (Salposky, 2005). Numerosi studi hanno dimostrato che in situazioni stressanti, accompagnate da stati di ansia e conflitti motivazionali, o successivamente ad un’interazione agonistica (Maestripieri et al., 1991), i Primati mostrano un’elevata frequenza di comportamenti di sostituzione (self-directed behaviors), che quindi possono essere considerati validi indicatori comportamentali dei loro stati emotivi. Lo scopo della mia ricerca è stato quello di analizzare le dinamiche sociali in una specie altamente despotica come Lemur catta, misurando quantitativamente la risposta emotiva di tali animali nell’ambito della stagione riproduttiva, particolarmente carica di tensione e stress sociale. Sono stati trovati livelli di scratching più elevati in seguito ad un’interazione aggressiva piuttosto che in un contesto rilassato; tale comportamento, inoltre, non è correlato con la posizione di rango degli individui e si presenta più frequentemente del self-grooming successivamente ad un’aggressione. Il comportamento di self-grooming, invece, è risultato correlato positivamente con le aggressioni subite dagli individui del gruppo e negativamente con quelle effettuate; la frequenza di tale comportamento non dipende dal contesto ed è risultata correlata alla posizione di rango occupata dagli individui del gruppo. Tali dati hanno fatto ipotizzare un’associazione tra comportamento di scratching e stress a breve termine e comportamento di self-grooming e stress a lungo termine. Per entrambi i comportamenti, i maschi presentano livelli maggiori rispetto alle femmine, soprattutto nella fase estro del periodo di studio. In tale fase è stata trovata anche una correlazione tra i due self-directed behaviors e il rango occupato dai membri del gruppo. È stata infine analizzata la distribuzione del grooming, valutando la sua possibile funzione come meccanismo per ridurre la tensione e lo stress (Terry, 1970; Keverne et al. 1989; Schino et al., 1988; Aureli et al., 1999) o come “merce di scambio” per l’accesso alle femmine in estro (mating market). È stata rilevata la presenza di reciprocità del grooming, indipendentemente dalla posizione di rango gerarchico; il grooming fatto dai maschi verso le femmine è risultato positivamente correlato con le aggressioni ricevute dai maschi ad opera delle femmine e, infine, nella fase estro, si è rilevata la reciprocità di tale comportamento tra maschi e femmine. Lo studio delle reazioni emotive sembrerebbe, quindi, un valido strumento per spiegare perché un animale metta in atto un determinato comportamento piuttosto che un altro e perché in uno stesso contesto individui diversi adottino strategie comportamentali diverse

Birth Experiences, Breastfeeding, and the Mother-Child Relationship: Evidence from a Large Sample of Mothers

Background: It is a priority for public health professionals to improve global breastfeeding rates, which have remained low in Western countries for more than a decade. Few researchers have addressed how maternal perceptions of birth experiences affect infant feeding methods. Furthermore, mixed results have been shown in research regarding breastfeeding and mother-child bonding, and many studies are limited by small sample sizes, representing a need for further investigation. Purpose: We aimed to examine the relationship between subjective birth experiences and breastfeeding outcomes, and explored whether breastfeeding affected mother-infant bonding. Methods: 3,080 mothers up to three years postpartum completed a cross – sectional survey. Results: Mothers who had more positive birth experiences were more likely to report breastfeeding their babies. Moreover, mothers who perceived their birth as more positive were more likely to breastfeed their child for a longer period (over 9 months) than those who had more negative experiences. In line with recent research, breastfeeding behaviours were not associated with reported mother-infant bonding. Conclusions: Mothers who reported better birth experiences were most likely to breastfeed, and breastfeed for longer. We find no evidence to suggest that feeding methods are associated with bonding outcomes

Similarities and differences in the functional architecture of mother-infant communication in rhesus macaque and British mother-infant dyads

Similarly to humans, rhesus macaques engage in mother-infant face-to-face interactions. However, no previous studies have described the naturally occurring structure and development of mother-infant interactions in this population and used a comparative-developmental perspective to directly compare them to the ones reported in humans. Here, we investigate the development of infant communication, and maternal responsiveness in the two groups. We video-recorded mother-infant interactions in both groups in naturalistic settings and analysed them with the same micro-analytic coding scheme. Results show that infant social expressiveness and maternal responsiveness are similarly structured in humans and macaques. Both human and macaque mothers use specific mirroring responses to specific infant social behaviours (modified mirroring to communicative signals, enriched mirroring to affiliative gestures). However, important differences were identified in the development of infant social expressiveness, and in forms of maternal responsiveness, with vocal responses and marking behaviours being predominantly human. Results indicate a common functional architecture of mother-infant communication in humans and monkeys, and contribute to theories concerning the evolution of specific traits of human behaviour

Neonatal face-to-face interactions promote later social behaviour in infant rhesus monkeys

In primates, including humans, mothers engage in face-to-face interactions with their infants, with frequencies varying both within and across species. However, the impact of this variation in face-to-face interactions on infant social development is unclear. Here we report that infant monkeys (Macaca mulatta) who engaged in more neonatal face-to-face interactions with mothers have increased social interactions at 2 and 5 months. In a controlled experiment, we show that this effect is not due to physical contact alone: monkeys randomly assigned to receive additional neonatal face-to-face interactions (mutual gaze and intermittent lip-smacking) with human caregivers display increased social interest at 2 months, compared with monkeys who received only additional handling. These studies suggest that face-to-face interactions from birth promote young primate social interest and competenc

Early predictors of impaired social functioning in male rhesus macaques (Macaca mulatta)

Autism spectrum disorder (ASD) is characterized by social cognition impairments but its basic disease mechanisms remain poorly understood. Progress has been impeded by the absence of animal models that manifest behavioral phenotypes relevant to ASD. Rhesus monkeys are an ideal model organism to address this barrier to progress. Like humans, rhesus monkeys are highly social, possess complex social cognition abilities, and exhibit pronounced individual differences in social functioning. Moreover, we have previously shown that Low-Social (LS) vs. High-Social (HS) adult male monkeys exhibit lower social motivation and poorer social skills. It is not known, however, when these social deficits first emerge. The goals of this study were to test whether juvenile LS and HS monkeys differed as infants in their ability to process social information, and whether infant social abilities predicted later social classification (i.e., LS vs. HS), in order to facilitate earlier identification of monkeys at risk for poor social outcomes. Social classification was determined for N = 25 LS and N = 25 HS male monkeys that were 1–4 years of age. As part of a colony-wide assessment, these monkeys had previously undergone, as infants, tests of face recognition memory and the ability to respond appropriately to conspecific social signals. Monkeys later identified as LS vs. HS showed impairments in recognizing familiar vs. novel faces and in the species-typical adaptive ability to gaze avert to scenes of conspecific aggression. Additionally, multivariate logistic regression using infant social ability measures perfectly predicted later social classification of all N = 50 monkeys. These findings suggest that an early capacity to process important social information may account for differences in rhesus monkeys’ motivation and competence to establish and maintain social relationships later in life. Further development of this model will facilitate identification of novel biological targets for intervention to improve social outcomes in at-risk young monkeys

Acute oxytocin improves memory and gaze following in male but not female nursery-reared infant macaques

Rationale: Exogenous oxytocin administration is widely reported to improve social cognition in human and nonhuman primate adults. Risk factors of impaired social cognition, however, emerge in infancy. Early interventions—when plasticity is greatest—are critical to reverse negative outcomes. Objective: We tested the hypothesis that oxytocin may exert similar positive effects on infant social cognition, as in adults. To test this idea, we assessed the effectiveness of acute, aerosolized oxytocin on two foundational social cognitive skills: working memory (i.e., ability to briefly hold and process information) and social gaze (i.e., tracking the direction of others’ gaze) in 1-month-old nursery-reared macaque monkeys (Macaca mulatta). We did not predict sex differences, but we included sex as a factor in our analyses to test whether our effects would be generalizable across both males and females. Results: In a double-blind, placebo-controlled design, we found that females were more socially skilled at baseline compared to males, and that oxytocin improved working memory and gaze following, but only in males. Conclusions: These sex differences, while unexpected, may be due to interactions with gonadal steroids and may be relevant to sexually dimorphic disorders of social cognition, such as male-biased autism spectrum disorder, for which oxytocin has been proposed as a potential treatment. In sum, we report the first evidence that oxytocin may influence primate infant cognitive abilities. Moreover, these behavioral effects appear sexually dimorphic, highlighting the importance of considering sex differences. Oxytocin effects observed in one sex may not be generalizable to the other sex

Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)

Motor, Social and Cognitive Development in Infant Rhesus Macaques (Macaca mulatta)

Motor cognition develops from a mutual and functional relation between perception and action. Several studies have demonstrated that, by a action-perception matching system, we represent observed and executed actions in a corresponding manner (Jeannerod, 2001; Knoblich & Flach, 2003; Gallese, Keyser & Rizzolatti, 2004: Jackson & Decety, 2004). Electrophysiological research has demonstrated that specific neurons, called mirror neurons, found in two areas of the primate brain (ventral premotor cortex and superior temporal sulcus) are selectively activated during the observation of actions executed by conspecifics (di Pellegrino et al. 1992; Gallese et al. 1996; Rizzolatti, Fadiga, Fogassi, & Gallese, 1996), providing evidence that such an observation–execution matching is involved in our ability to recognize and understand the actions of others. Since shared representations relies on a common computational code and neural architecture, our aim was to explore two different aspects of motor cognition, such as organization of actions and imitation of the others actions. In Experiment 1, we investigated the emergence and the development of prehensile skills in infant macaques over the first month of life, to better understand how infants construct a motor representation of actions in relation to the task and environmental constraints. We found that our infants showed clear goal-directed movements towards the object as early as the second week of life and that their flexibility and selectivity of motor responses improved remarkably with age. Our data also showed that infant macaques were able to adjust their actions in relation to the perceived object size and organize their reaching-grasping responses accordingly. The intent of Experiment 2 was to explore the development of spatial perception and representation in infants and their ability to modulate actions when the object was placed in the near and far space and how infants construct a map of surrounding world in relation to the representation of their own body. The results revealed that monkey infants gradually improved their capability to perceive objects at a certain distance and direction in space, and thus to use this information in order to plan different motor strategies and to adjust the hand configuration accordingly. Infants seemed to code the peripersonal space in a arm-centered coordinate system since the onset of a successful reaching. In contrast, starting from the third week of life, infants started to move physically toward the object and to use their own body as a tool to expand their peripersonal space. By including the body in the action, infants induced changes in the body schema and expanded near space representation in a body-centered coordinate system. These changes in the reaching strategy used by the infants probably reflected an improvement in their capacity to move the whole body and to coordinate more precise movements. Furthermore, our data showed that changes in body schema can influence also infants’ perception of object in space and their flexibility in choosing a different grip configuration according to the size and the position in space of the target. Taken together, these findings suggest that several brain mechanisms of intermodal integration between visual proprioceptive information and motor movements might be already formed after birth, although only broadly defined, and that sensori-motor experience and learning might help infant to sequentially and successfully acquire new motor capabilities. The emergence of such visuo–motor integration may account also for the match between visual input and motor output in imitation tasks. The ability to recognize to be imitated requires the existence of a matching mechanism between visual and proprioceptive information. To this aim, in Experiment 3 we investigated the development of the infants ability to recognize when they were being imitated and the effect of imitiation on affiliation and social interaction. This experiment demonstrated that imitation can significantly affect the behavior of the infant monkeys and facilitate an affective connection with the caregiver: infants, in fact, looked longer and lipsmacked more at the experimenter both during the imitation and after being imitated. These results demonstrate that from early in life imitation might be used as a privileged form of communication which provides essential social inputs for the maturation of the infant’s relational and social skills. Moreover, our data suggest the existence of an early functioning recognition mechanism, possibly based on a mirror neurons system

Scratching around mating: Factors affecting anxiety in wild Lemur catta

Scratching has been successfully used to detect anxiety, a proxy for stress, in primates, from strepsirrhines to Homo sapiens. Here, we investigated the fluctuation of scratching in Lemur catta during the mating season. In particular we evaluated whether scratching (1) varied according to sex and rank differences, (2) increased in the period of maximum stress (around the mating days), and (3) was reduced by grooming. At Berenty (South Madagascar), we followed two lemur groups (23 adult/subadult individuals) and gathered data on self-scratching, aggression, and grooming. Based on perineal area features, we recognized two periods: low swelling (LS), with no estrus female, and high swelling (HS), when at least one female was in estrus. We predicted that aggressive behaviors and anxiety-related scratching would covary. Indeed, scratching peaked in HS, when aggression was also highest. In agreement with previous literature, this result suggests that conflicts around estrus days may raise anxiety levels in the social group. We expected scratching levels to be highest in males because they aggressively compete for females and are subject to mate choice and repeated attacks by dominant females. Instead, the scratching rates were similar in males and females, probably because the high competition, which involves both sexes, dampened intersexual differences. In contrast to our prediction, scratching was not rank dependent, probably because animal ranking positions changed from LS to HS. Finally, we showed that, in ring-tailed lemurs, as well as in other primates, scratching decreases after reciprocal grooming in both periods. This finding provides the first evidence that grooming could assist in reducing anxiety in strepsirrhines

Methodological details.

<p>Procedure (A), examples of lipsmacking, tongue protrusion, and control stimuli (B), and examples of infants' gestures (C). Human models portrayed here have given written informed consent, as outlined in the PLOS consent form, for publication of their photographs.</p