Sheree L. Watson

Effects of chronic social separation on cardiovascular disease risk factors in female cynomolgus monkeys

A lack of social support is associated with increased risk of coronary heart disease morbidity and mortality in human beings. Similarly, chronic social separation (single cage housing) potentiates atherosclerosis in female monkeys. Under the hypothesis that autonomic arousal and/or ovarian impairment may mediate this effect (as both are associated with increased atherosclerosis), heart rate and luteal phase plasma progesterone concentrations were measured in 12 female cynomolgus monkeys that were first socially housed, then individually housed, and finally returned to their original social groups. Afternoon heart rates increased during social separation compared to the social groupings (P < 0.001). Increased heart rates could not be explained by activity levels, which were lower during social separation than in social groupings (P < 0.001). Ovarian function (i.e. luteal-phase progesterone concentrations) was not influenced by housing condition. Single caging reduced the extent of social signaling, even though animals were in visual and auditory contact. Rates of affiliative behaviors increased and time spent alone decreased in post-reunion social groups compared to pre-separation social groups (Ps < 0.01). The results indicate that chronic social separation in this group-living species may exacerbate atherosclerosis via altered autonomic activity, as evidenced by higher heart rates during social separation.

Rating vs. coding in animal personality research

Animal personality research has become increasingly popular over the past few decades. The two main methods used to examine individual differences in animals are rating and coding. The rating method involves human scoring of an animals behavioral tendencies along various behavioral dimensions, such ratings are typically based on the human raters experience with the animal. The coding method also requires humans to score an animals behavior, but differs in that the scoring is based on the animals immediate behavior in a specific context. This brief report describes the use of both the rating and coding methods to examine personality within a group of 10 Garnetts bushbabies (Otolemur garnettii). The results indicated that individual personalities do exist in bushbabies, but also suggested that the rating method is heavily influenced by the raters experience with an animal. Consequently, it is important that the nature of the raters interactions with the target animals be considered when using the rating method to assess animal personality.

Can puzzle feeders be used as cognitive screening instruments? Differential performance of young and aged female monkeys on a puzzle feeder task

Conventional cognitive testing of monkeys is time‐consuming and involves single‐caging and food or water deprivation. Here we report a novel test of global cognitive performance that can be completed in a short time period without food/water or social restrictions. Nine mazes of increasing difficulty were developed using a standard puzzle feeder, and the maze‐solving performance of ten young and five aged female cynomolgus monkeys (Macaca fascicularis) was tested. The young monkeys solved maze configurations at higher levels of difficulty and solved the first level of difficulty more quickly than aged monkeys. This task discriminated performance by age in nonhuman primates as do more conventional forms of cognitive testing and indicates that this task may be a quick and easy assessment of global cognitive function. Am. J. Primatol. 49:195–202, 1999.

Prosimian Primates as Models of Laterality

Abstract Prosimians are the most distantly related primates to humans and are unique subjects for studies of behavioral asymmetries. This chapter outlines the values of research from prosimians toward evolutionary models of hemispheric specialization in primates. We first review the evidence of functional asymmetries including handedness in prosimians. We next summarize the influence of posture and arousal on the strength and direction of hand preferences. In addition, the influence of age and sex on behavioral asymmetries and handedness are discussed in the context of lateralization being exhibited as a whole body phenomenon.

Multiple Measures of Laterality in Garnett's Bushbaby (Otolemur garnettii)

Behavioral laterality, a common measure of hemispheric specialization of the brain, has been examined in multiple tasks across several species of prosimian primates; however, there is inconsistency among findings between and within species that leaves many questions about laterality unanswered. Most studies have employed few measures of laterality, most commonly handedness. This study examined multiple measures of laterality within subjects in 17 captive‐born Garnetts bushbabies (Otolemur garnettii) to assess the consistency of lateralized behaviors and to examine possible influences such as age, posture, novelty, and arousal to elucidate the relations between direction and strength of laterality. We measured reaching, turning bias, scent marking, tail wrapping, leading foot, side‐of‐mouth preference, and hand use in prey capture. Because autonomic arousal has been invoked as a determinant of strength of lateralization, we included multiple tasks that would allow us to test this hypothesis. All subjects were significantly lateralized on simple reaching tasks (P<0.01) and tail wrapping (P<0.01). Moreover, the number of animals lateralized on turning (P<0.01), leading limb (P<0.05), mouth use (P<0.01), and prey capture (P<0.01) was greater than would be expected by chance alone. There was consistency in the strength and direction of hand biases across different postures. Tasks requiring hand use were more strongly lateralized than tasks not involving hand use (P<0.001). The data do not support the assumption that arousal (as subjectively categorized) or novelty strengthens lateralized responding. The results of this study are discussed in terms of the effects of arousal, posture, and age on lateralized behavior. Am. J. Primatol. 72:206–216, 2010.

Behavioral responses to ovariectomy and chronic anabolic steroid treatment in female cynomolgus macaques.

A pilot study was conducted to investigate the effects of ovariectomy on rates of aggressive and affiliative behavior, as well as body size, in 38 young adult female cynomolgus monkeys (Macaca fascicularis) living in isosexual social groups of four to five animals. In addition, we assessed the effects of nandrolone decanoate (an anabolic steroid used for postmenopausal hormone replacement therapy) on indices of aggression, submission, and body size. Animals were randomized into three experimental conditions: 1) sham ovariectomized, untreated (SHAM); 2) ovariectomized, untreated (OVX); and, 3) ovariectomized, treated with nandrolone decanoate for 24 months (NAN). Each individual was observed for 10 min, one to two times per month, and all instances of agonistic and affiliative behavior were recorded by means of focal animal sampling. Ovariectomized, untreated animals exhibited a two- to threefold increase in aggression compared to SHAM or NAN animals; F(2, 32) = 4.09, p = 0.026; however, the expression of prosocial or affiliative behaviors as measured by rates of grooming and initiating friendly behavior was unaffected. At an i.m. dose of 25 mg every 2 weeks, nandrolone decanoate caused a 60% increase in body weight of the animals compared to untreated intact and ovariectomized animals, F(2, 31) = 161.57, p < 0.0001.

Handedness and Lateralised Tympanic Membrane Temperature in Relation to Approach-Avoidance Behaviour in Garnett's Bushbaby (Otolemur garnettii)

Studies of handedness suggest a relationship between hemispheric specialisation and emotional processing. Recently measures of lateralised tympanic membrane temperature (TMT) have identified similar relationships (i.e., the left hemisphere is involved in approach behaviour and the right hemisphere avoidance behaviour). In the present study we examined lateralised changes in TMT in response to social interaction in 10 Garnetts bushbabies. Additionally, we examined whether handedness could be used as a predictor of approach–avoidance tendencies. We found a positive association between temperature change and both allogrooming and affiliative approach. Social behaviour did not differ between right- and left-handed bushbabies. These findings are discussed in terms of existing theories of asymmetric emotional processing. Overall, the data suggest that there is a left hemisphere specialisation for processing approach-related behaviours, which is consistent with existing models of lateralised emotional processing. Our data also indicate that TMT is a reliable, cost-effective measure of cerebral activation that is less invasive and more practical than alternative measures such as EEG, PET, and fMRI.

Food reinforcement effects on tympanic membrane temperature in response to restraint stress in Garnett’s bushbaby (Otolemur garnettii)

Tympanic membrane thermometry is a cost-effective replacement for functional magnetic resonance imaging and positron emission tomography to measure cerebral activation for the ipsilateral hemisphere [1]. Because the brain tissue is warmer than the blood flowing through it, decreases in tympanic membrane temperature (TMT) indicate an increase in blood flow to the brain, which is thought to be related to an increase in cerebral activation [2]. In addition to its role in standard husbandry, TMT has been used in a variety of experimental settings to assess the brain’s response to environmental stimuli. Parr and Hopkins [3] used TMT to assess the hemispheric activation in response to positive, negative, and neutral emotional stimuli in chimpanzees (Pan troglodytes) and found an increase in TMT in the right ear in response to videos with a negative emotional connotation. Other studies have shown bilateral increases in temperature associated with fearfulness and negative affectivity [4]. For example, marmosets (Callithrix penicillata) with more extensive histories of capture and restraint had lower right ear temperatures than marmosets with fewer captures [5]. This study examined whether restraint stress affected TMT in Garnett’s bushbaby. We also assessed whether positive and negative reinforcement would affect the stress-related change in TMT.

Age-related decline in lateralised prey capture success in Garnett's bushbaby (Otolemur garnettii)

We examined differences in prey capture success when reaching for moving prey with the preferred and non-preferred hand (as determined previously using stationary food items) in 12 Garnetts bushbabies (Otolemur garnettii). Hand preference was determined by a test of simple reaching for stationary food items. We assessed both the frequency of hand use and success rates for each hand in capturing live mealworms. We also examined the effect of age on overall prey capture success. Subjects were individually presented with live mealworms in a cup partially filled with a cornmeal medium. The preferred hand was used significantly more often than the non-preferred hand to obtain the moving prey; however, no differences were found in the frequency of usage of the left vs the right hand. Furthermore, there were no differences in the success rates of the left vs the right hand, nor the preferred vs the non-preferred hand. There was a significant negative correlation between age and prey capture success. These data suggest that age, rather than preferred hand, may be the most relevant factor in the bushbabies’ prey capture success.

Characterization of cerebrospinal fluid monoamine metabolites in peripubertal chimpanzees (Pan troglodytes).

Background  Assessment of cerebrospinal (CSF) monoamine metabolites 5‐hydroxyindoeacetic acid (5‐HIAA) and homovanillic acid (HVA), and the serotonin precursor tryptophan (TRP), in chimpanzees may help in understanding the neurobiology underlying aggressive, impulsive behavior in humans and non‐human primates.