Publications

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    ABSTRACT: 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 Garnett's 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.
    Laterality 02/2012; · 1.13 Impact Factor
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    ABSTRACT: 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 Garnett's 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.
    Laterality 01/2012; 17(1):111-118. · 1.13 Impact Factor
  • Journal of Medical Primatology 07/2011; 40(5):354-6. · 1.11 Impact Factor
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    ABSTRACT: 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 Garnett's 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.
    American Journal of Primatology 12/2009; 72(3):206-16. · 2.46 Impact Factor
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    ABSTRACT: 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. Two CSF samples were obtained from 11 peripubertal chimpanzees 8 months apart and were assayed for monoamine metabolite and TRP concentrations. Substantial inter-individual stability was observed for 5-HIAA (n = 11; r = 0.83, P < 0.001) and HVA (r = 0.91, P < 0.001). Females had significantly higher concentrations of 5-HIAA compared to males (F(1,8) = 7.31; P < 0.05). Levels of 5-HIAA (r = -0.62, P < 0.05), HVA (r = -0.86, P < 0.001) and TRP levels (r = -0.67; P < 0.05) decreased with age. Close parallels were observed between chimpanzees and humans with respect to absolute levels, sex effects, ontogeny, and 5-HIAA-HVA correlations, supporting the potential utility of the measures in understanding relationships between monoamine functioning and behavior in chimpanzees and humans.
    Journal of Medical Primatology 10/2009; 39(1):24-31. · 1.11 Impact Factor
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    ABSTRACT: Research suggests that auditory environmental enrichment might reduce abnormal behavior in certain primate species. The authors evaluated the behavioral effects of exposure to music in a prosimian primate (Garnett's bushbaby; Otolemur garnettii). They exposed bushbabies to a Mozart concerto for 15 min per day for 20 d (5 h exposure total), video-recorded them and subsequently analyzed the frequency of subjects' grooming and stereotypic behaviors. The authors compared the data with baseline behavioral data that had been recorded over a 20-d period before the experimental treatment. Neither stereotypy nor grooming behavior varied as a result of exposure to music. These results do not support the hypothesis that auditory enrichment in the form of exposure to music is an effective means of reducing stereotypic behavior in O. garnettii.
    Lab Animal 05/2009; 38(4):122-5. · 0.47 Impact Factor
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    ABSTRACT: Self-injurious behavior (SIB) among captive primates is a recurring problem for those who manage such facilities. Its prevalence highlights the need for research evaluating the effectiveness of potential treatment approaches. In the present study, 4 wk of dietary supplementation with L-tryptophan (100 mg daily) was evaluated for the treatment of self-inflicted wounds in 22 small-eared bushbabies, a prosimian primate, with a history of SIB. The treatment significantly reduced stereotypy and was associated with a reduction in wound area and severity. In terms of physiologic measures, preexisting high levels of cortisol were reduced in bushbabies with SIB, whereas serotonin concentrations were increased after 4 wk of treatment. Results indicate that L-tryptophan as a dietary supplement may be a viable adjunct to standard husbandry procedures for animals exhibiting maladaptive behaviors such as stereotypy and SIB.
    Journal of the American Association for Laboratory Animal Science: JAALAS 04/2009; 48(2):185-91. · 1.15 Impact Factor
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    ABSTRACT: We examined the extent to which female capuchin monkeys show an ‘aversion to inequitable work effort’ by providing the monkeys with the opportunity to engage in token exchange tasks to earn either a preferred (grape) or nonpreferred (oat cereal) food item. In experiment 1, monkeys were paired with partners such that both were required to exchange a token (work effort) for either a preferred or nonpreferred food reward. The subject's exchange behaviour was then compared to conditions in which the partner received the food reward for no work effort. We found no evidence that differential work effort influenced the percentage of incomplete exchanges. Furthermore, capuchins completed exchanges more rapidly for the preferred food item, regardless of the work effort of the partner. In experiment 2, we evaluated, in the absence of differential work effort, behavioural responses of monkeys to receipt of a preferred or nonpreferred food in conditions where their partner received either the same or different food. These conditions were compared to control conditions where either the same or different food was placed in an adjacent empty cage. Capuchins were less likely to accept nonpreferred food and consumed it more slowly than preferred food. We found no evidence that the presence of a partner influenced acceptance or consumption of the nonpreferred food under inequitable conditions. Overall, we found no indication that capuchins are able to evaluate either the relative work effort of a partner or the inequity of a food reward and are thus unlikely to possess an ‘aversion to inequity’.
    Animal Behaviour - ANIM BEHAV. 01/2007; 74(3):487-496.
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    ABSTRACT: Relocation of research animals, either within a facility or from one facility to another, is assumed to be stressful. Development of appropriate research methodologies may be facilitated by understanding the extent and duration of the physiological response to relocation stress and whether the stress can be buffered by environmental or social factors, such as the presence of a cagemate. To characterize the response to relocation stress in Garnett's bushbaby, we assessed cortisol concentrations in nine female and six male bushbabies during relocation to a different facility; six of the animals were pair-housed at the time of the move and were moved with their respective cagemates. Fecal cortisol was assessed at three time points: 1) baseline (1 day prior to moving); 2) relocation (the day the animals were relocated); and 3) post-relocation (7 days after relocation). Cortisol concentrations were higher at the relocation time point than at baseline and post-relocation, which did not differ. Cortisol concentration did not differ as a function of having a cagemate during relocation. Although relocation resulted in a significant (P < 0.05) increase in cortisol excretion concentration, the levels returned to baseline within 7 days after the stressor.
    Contemporary topics in laboratory animal science / American Association for Laboratory Animal Science 05/2005; 44(3):22-4. · 0.82 Impact Factor
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    ABSTRACT: In an investigation of cortisol secretion in fully mature, ovariectomized cynomolgus monkeys (Macaca fascicularis), we compared monkeys that were given either placebo (OVX, n = 26) or 17beta estradiol (E(2 )) (EST, n = 26) in a daily oral dose. Serum cortisol concentrations were measured prior to the experimental manipulation and 3, 6, 9, and 12 months following initiation of treatment. Pretreatment cortisol values did not differ between groups. Assessment of the treatment period values revealed that cortisol concentrations were significantly higher ( approximately 10%) in the EST than in the OVX monkeys. Cortisol also varied significantly across periods of sampling. This time-dependent variation was attributable to elevations in months 6 and 9 (when daylight was generally long), relative to months 3 and 12 (when daylight was relatively short). The modest stimulatory effect of estrogen on corticosteroid production observed in this study is consistent with what has been seen in women, and contrasts with the more robust effects observed in New World monkeys. The possible relationship between season and cortisol secretion observed here has not been previously described in monkeys.
    American Journal of Primatology 06/2003; 60(1):17-22. · 2.46 Impact Factor
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    ABSTRACT: The relationships among social rank, basal cortisol concentrations, and social behavior were assessed in adult female cynomolgus monkeys (Macaca fascicularis). Subjects were 157 unrelated, reproductively intact animals housed in 30 small groups. Rank determinations were made monthly. Blood samples were collected on two occasions, 4.5 and 7.5 months following initial group formation. Regular behavioral observations were conducted on a subset of animals over a period of 4 weeks, 9 months following group formation. Analyses revealed that serum cortisol values were significantly correlated across the two sampling periods, with no significant change in absolute values. While social rank was positively correlated across both samples, there was no relationship between rank and cortisol. However, dominant and subordinate animals did differ in the rates of performance of aggressive and submissive behaviors. These data suggest that social rank does not influence baseline serum cortisol in adult female cynomolgus monkeys, despite stability in measures of rank and cortisol and the presence of the usual behavioral differences between dominants and subordinates.
    Hormones and Behavior 06/2001; 39(3):232-8. · 3.74 Impact Factor
  • S L Watson, C A Shively, M L Voytko
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    ABSTRACT: 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.
    American Journal of Primatology 11/1999; 49(2):195-202. · 2.46 Impact Factor
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    ABSTRACT: Many diurnal anthropoid species direct social behaviors toward their own mirror-image as though viewing a conspecific. To determine whether a nocturnal prosimian species would behave similarly, we videotaped social responses of 45 Garnett's greater bush babies (Otolemur garnettii) observing mirror-images for the first time, scored them for frequency and duration, and compared them with the same behaviors directed elsewhere in the test apparatus. Males scentmarked more than females did, principally with the hindfoot, and most when in immediate proximity to the mirror. Bush babies displayed bipedal posture and threat gestures when oriented directly toward a mirror from a near position. Orientation toward the mirror also increased the frequency of arched-back postures; however, this behavior was not contingent on proximity to the mirror or visibility of the mirror-image. The differential expression of specific behaviors toward mirror-images by male and female bush babies supports the view that this nocturnal prosimian, thought to be dependent on olfaction and audition for communication, is capable of specific recognition by visual cues alone.
    International Journal of Primatology 09/1999; 20(5):633-650. · 1.79 Impact Factor
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    ABSTRACT: Among prosimians, some types of scent-marking may serve as displacement activities that reduce physiological arousal in stressful situations. Type and frequency of scent-marking was measured for 22 male small-eared or Garnett's bushbabies (Otolemur garnettii) exposed to a novel open field environment, with and without novel objects. Rates of foot rubbing, chest rubbing, urine washing, flank rubbing, and ano-genital marking were measured. Foot and chest rubbing constituted 92.5% of responses. Type and frequency of scent-marking was compared to the magnitude of the animals' cortisol responses in a separate test of restraint stress. Only foot and chest rubbing were systematically related to cortisol levels. The animals that performed these behaviors more in the novel environment also exhibited lower cortisol responses to restraint stress. These results suggest that bushbabies that characteristically employ behavioral coping strategies have a reduced physiological response to psychological stressors.
    Physiology & Behavior 07/1999; 66(4):695-9. · 3.16 Impact Factor
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    ABSTRACT: 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.
    Physiology & Behavior 04/1999; 66(1):95-100. · 3.16 Impact Factor
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    ABSTRACT: 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 (P's < 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.
    Atherosclerosis 05/1998; 137(2):259-66. · 3.71 Impact Factor
  • Sheree L. Watson, Jeannette P. Ward
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    ABSTRACT: Bushbabies ( Otolemur garnettii) were tested in an empty open field, with novel objects, and with a caged live snake. Each was also tested in the home cage on a latch-box problem. Principal-components analysis of novelty test scores revealed 4 factors (activity, curiosity, boldness, escape). Factor scores were collapsed into an index of behavioral inhibition and analyzed for group effects. Left-handed (LH) subjects were less inhibited than right-handed subjects. Underlying factor scores showed laterality effects only in activity: a main effect with LH subjects more active, an interaction with young, LH subjects higher on activity than other groups. The 17 subjects that solved the latch-box problem had higher scores on curiosity than the 18 that attempted but did not solve the problem. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
    Journal of Comparative Psychology 11/1996; 110(4):377-385. · 1.89 Impact Factor
  • Sheree L. Watson, Martha Schiff, Jeannette P. Ward
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    ABSTRACT: Thirty-eight bushbabies(Otolemur garnettii)were subjects in an observational learning study. We exposed them to one of three modeling conditions: (1) fishing model—one that actually performed fishing behavior; (2) nonfishing model—one that performed as a model in every way except performance of fishing behavior; and (3) no model. We assessed them with regard to latency to approach the fishbowl, latency to make an initial fishing attempt, duration of time spent in the vicinity of the fishbowls, and number of actual fishing attempts. Results indicate that subjects that were exposed to either fishing or nonfishing models were faster to approach the fishbowls and spent more time in the vicinity of the fishbowls than animals in the no-model condition Lineage, i.e., whether or not the animals’ parents fished, rather than modeling condition, was the best predictor of the latency to initial fishing attempt and the number of attempts made.
    International Journal of Primatology 01/1994; 15(4):507-519. · 1.79 Impact Factor
  • Sheree L. Watson, David B. Hanbury
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    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.
    Special Topics in Primatology.

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