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 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.

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 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.

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 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.

L-tryptophan and correlates of self-injurious behavior in small-eared bushbabies (Otolemur garnettii).

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.

Efficacy of auditory enrichment in a prosimian primate (Otolemur garnettii).

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.

Cortisol response to relocation stress in Garnett's bushbaby (Otolemur garnettii).

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.