Papers by Kimberley Phillips
Genes
Capuchins are platyrrhines (monkeys found in the Americas) within the Cebidae family. For most of... more Capuchins are platyrrhines (monkeys found in the Americas) within the Cebidae family. For most of their taxonomic history, the two main morphological types of capuchins, gracile (untufted) and robust (tufted), were assigned to a single genus, Cebus. Further, all tufted capuchins were assigned to a single species, Cebus apella, despite broad geographic ranges spanning Central and northern South America. In 2012, tufted capuchins were assigned to their genus, Sapajus, with eight currently recognized species and five Cebus species, although these numbers are still under debate. Alu retrotransposons are a class of mobile element insertion (MEI) widely used to study primate phylogenetics. However, Alu elements have rarely been used to study capuchins. Recent genome-level assemblies for capuchins (Cebus imitator; [Cebus_imitator_1.0] and Sapajus apella [GSC_monkey_1.0]) facilitated large scale ascertainment of young lineage-specific Alu insertions. Reported here are 1607 capuchin specific...
Frontiers in Psychology, 2019
Collecting publishable data with only undergraduate research assistants (RAs) is difficult; condu... more Collecting publishable data with only undergraduate research assistants (RAs) is difficult; conducting research with young children or non-human primates (NHPs) adds a layer of difficulty, yet we have been able to successfully sustain and grow research programs in Developmental Psychology and primate Behavioral Neuroscience at Trinity University (TU), a primarily undergraduate institution (PUI) in San Antonio. We each have been conducting research for over 25 years, with most of that time at this type of institution, and have developed effective strategies for publishing articles with undergraduates in this environment. SETTING GOALS A primary strategy is to set long-term, high-level goals, and work backwards to identify short-term tasks that keep the work focused toward these goals (e.g., Wilkowski and Ferguson, 2016). We subscribe to the "2 weeks, 2 months, 2 years" method, wherein we identify goals (i.e., project completed, manuscript submitted) to be accomplished in 2 years. We then identify tasks to be completed in the next 2 weeks (i.e., literature search) and 2 months (i.e., number of participants run). Involving RAs in this process allows them to see how their contributions contribute to long-term goals. Additionally, we have found that setting up schedules for training and working in the lab within the first week of each semester is a key to getting undergraduates successfully engaged. Undergraduates can be overcommitted, and their schedules fill rapidly. Putting lab times into their schedules early, in writing, is important.
Genome biology and evolution, Mar 1, 2017
The adaptive significance of human brain evolution has been frequently studied through comparison... more The adaptive significance of human brain evolution has been frequently studied through comparisons with other primates. However, the evolution of increased brain size is not restricted to the human lineage but is a general characteristic of primate evolution. Whether or not these independent episodes of increased brain size share a common genetic basis is unclear. We sequenced and de novo assembled the transcriptome from the neocortical tissue of the most highly encephalized nonhuman primate, the tufted capuchin monkey (Cebus apella). Using this novel data set, we conducted a genome-wide analysis of orthologous brain-expressed protein coding genes to identify evidence of conserved gene-phenotype associations and species-specific adaptations during three independent episodes of brain size increase. We identify a greater number of genes associated with either total brain mass or relative brain size across these six species than show species-specific accelerated rates of evolution in i...
Neuropsychologia, 2016
Increases brain size has been hypothesized to be inversely associated with the expression of beha... more Increases brain size has been hypothesized to be inversely associated with the expression of behavioral and brain asymmetries within and between species. We tested this hypothesis by analyzing the relation between asymmetries in the planum temporale (PT) and different measures of the corpus callosum (CC) including surface area, streamline count as measured from diffusion tensor imaging, fractional anisotropy values and the ratio in the number of fibers to surface area in a sample of chimpanzees. We found that chimpanzees with larger PT asymmetries in absolute terms had smaller CC surface areas, fewer streamlines and a smaller ratio of fibers to surface area. These results were largely specific to male but not female chimpanzees. Our results partially support the hypothesis that brain asymmetries are linked to variation in corpus callosum morphology, although these associations may be sex-dependent.
Frontiers in psychology, 2015
A number of factors have been proposed to influence within and between species variation in hande... more A number of factors have been proposed to influence within and between species variation in handedness in non-human primates. In the initial study, we assessed the influence of grip morphology on hand use for simple reaching in a sample of 564 great apes including 49 orangutans Pongo pygmaeus, 66 gorillas Gorilla gorilla, 354 chimpanzees Pan troglodytes and 95 bonobos Pan paniscus. Overall, we found a significant right hand bias for reaching. We also found a significant effect of the grip morphology of hand use. Grasping with the thumb and index finger was more prevalent in the right compared to left hand in all four species. There was no significant sex effect on the patterns of handedness. In a subsample of apes, we also compared consistency in hand use for simple reaching with previously published data on a task that measures handedness for bimanual actions. We found that the ratio of subjects with consistent right compared to left hand use was more prevalent in bonobos, chimpanz...
Neuroscience, Jan 27, 2012
Capuchin monkeys (Cebus apella) are New World primates with relatively large brains for their bod... more Capuchin monkeys (Cebus apella) are New World primates with relatively large brains for their body size. The developmental trajectories of several brain regions-including cortical white matter, frontal lobe white matter, and basal ganglia nuclei-are similar to humans. Additionally, capuchins have independently evolved several behavioral and anatomical characteristics in common with humans and chimpanzees-including complex manipulative abilities, use of tools, and the use of precision grips-making them interesting species for studies of comparative brain morphology and organization. Here, we report the first investigation into the development of the corpus callosum (CC) and its regional subdivisions in capuchins. CC development was quantified using high-resolution structural magnetic resonance imaging (MRI) images from 39 socially reared subjects (male n=22; female n=18) ranging in age from 4 days (infancy) to 20 years (middle adulthood). The total area of the CC and the subdivisions...
Twin Research and Human Genetics, 2012
The degree to which genes and environment determine variations in brain structure and function is... more The degree to which genes and environment determine variations in brain structure and function is fundamentally important to understanding normal and disease-related patterns of neural organization and activity. We studied genetic contributions to the midsagittal area of the corpus callosum (CC) in pedigreed baboons (68 males, 112 females) to replicate findings of high genetic contribution to that area of the CC reported in humans, and to determine if the heritability of the CC midsagittal area in adults was modulated by fetal development rate. Measurements of callosal area were obtained from high-resolution MRI scans. Heritability was estimated from pedigree-based maximum likelihood estimation of genetic and non-genetic variance components as implemented in Sequential Oligogenic Linkage Analysis Routines (SOLAR). Our analyses revealed significant heritability for the total area of the CC and all of its subdivisions, with h2 = .46 for the total CC, and h2 = .54, .37, .62, .56, and ....
Journal of Comparative Neurology, 2014
Neuroscience Letters, May 8, 2012
Curiosity is a cornerstone of cognition that has the potential to lead to innovations and increas... more Curiosity is a cornerstone of cognition that has the potential to lead to innovations and increase the behavioral repertoire of individuals. A defining characteristic of curiosity is inquisitiveness directed toward novel objects. Species differences in innovative behavior and inquisitiveness have been linked to social complexity and neocortical size [18]. In this study, we observed behavioral actions among nine socially reared and socially housed capuchin monkeys in response to an unfamiliar object, a paradigm widely employed as a ...
Proceedings. Biological sciences / The Royal Society, Jan 7, 2015
Interhemispheric communication may be constrained as brain size increases because of transmission... more Interhemispheric communication may be constrained as brain size increases because of transmission delays in action potentials over the length of axons. Although one might expect larger brains to have progressively thicker axons to compensate, spatial packing is a limiting factor. Axon size distributions within the primate corpus callosum (CC) may provide insights into how these demands affect conduction velocity. We used electron microscopy to explore phylogenetic variation in myelinated axon density and diameter of the CC from 14 different anthropoid primate species, including humans. The majority of axons were less than 1 µm in diameter across all species, indicating that conduction velocity for most interhemispheric communication is relatively constant regardless of brain size. The largest axons within the upper 95th percentile scaled with a progressively higher exponent than the median axons towards the posterior region of the CC. While brain mass among the primates in our analy...
1. Center for the Advanced Study of Hominid Paleobiology and Department of Anthropology, The Geor... more 1. Center for the Advanced Study of Hominid Paleobiology and Department of Anthropology, The George Washington University, Washington DC 20052 2. Dallas Zoo, Dallas, TX 75203 3. Mountain Gorilla Veterinary Project, School of Veterinary Medicine, University of California Davis, Davis, CA 95616 4. Department of Life Sciences, University of Coimbra, 3001-056 Coimbra, Portugal 5. Neuroscience Institute, Georgia State University, Atlanta, GA 30303 6. Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Atlanta, GA 30329 7. Cleveland Metroparks Zoo, Cleveland, OH 44109 8. Rwanda Development Board, Department of Tourism and Conservation, Kigale, Rwanda 9. Department of Psychology, Trinity University, San Antonio, TX 78212 10. Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, OH 44240 11. Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10...
PeerJ
Hair cortisol concentration (HCC) provides a long-term retrospective measure of hypothalamic–pitu... more Hair cortisol concentration (HCC) provides a long-term retrospective measure of hypothalamic–pituitary–adrenal axis activity, and is increasingly used to assess the life history, health and ecology of wild mammals. Given that sex, age, season and pregnancy influence HCC, and that it may indicate ongoing stress, we examined HCC in common marmosets (Callithrix jacchus) naturally inhabiting a hot and dry semi-desert like habitat, Caatinga, in northeastern Brazil. We trapped, measured, weighed, marked and collected shaved hair from the back of the neck of 61 wild marmosets during the wet and dry seasons. Using enzyme immunoassay, we found that HCC was higher in the dry season compared with the wet season among all age/sex classes. Females had significantly higher HCC than males, juveniles had higher HCC than adults, and reproductively active adult females and non-pregnant/non lactating adult females did not differ in HCC. There were no interaction effects of sex, age, group, or season o...
American Journal of Primatology
Quantifying cortisol concentration in hair is a non-invasive biomarker of long-term hypothalamicp... more Quantifying cortisol concentration in hair is a non-invasive biomarker of long-term hypothalamicpituitary-adrenal (HPA) activation, and thus can provide important information on laboratory animal health. Marmosets (Callithrix jacchus) and capuchins (Cebus apella) are New World primates increasingly used in biomedical and neuroscience research, yet published hair cortisol concentrations for these species are limited. Review of the existing published hair cortisol values from marmosets reveals highly discrepant values and the use of variable techniques for hair collection, processing, and cortisol extraction. In this investigation we utilized a well-established, standardized protocol to extract and quantify cortisol from marmoset (n = 12) and capuchin (n = 4) hair. Shaved hair samples were collected from the upper thigh during scheduled exams and analyzed via methanol extraction and enzyme immunoassay. In marmosets, hair cortisol concentration ranged from 2710-6267 pg/mg and averaged 4070 ± 304 pg/mg. In capuchins, hair cortisol concentration ranged from 621-2089 pg/mg and averaged 1092 ± 338 pg/mg. Hair cortisol concentration was significantly different between marmosets and capuchins, with marmosets having higher concentrations than capuchins. The incorporation of hair cortisol analysis into research protocols provides a non-invasive measure of HPA axis activity over time, which offers insight into animal health. Utilization of standard protocols across laboratories is essential to obtaining valid measurements and allowing for valuable future cross-species comparisons.
American Journal of Primatology
The development of the marmoset as a translational model for healthspan and lifespan studies reli... more The development of the marmoset as a translational model for healthspan and lifespan studies relies on the characterization of health parameters in young and geriatric marmosets. This crosssectional study examined health phenotypes in marmosets for five domains of interest for human health and aging: mobility, cognition, metabolism, homeostasis, and immune function. Geriatric marmosets were found to have significant executive function impairment when compared to young animals. While geriatric animals did not show gross abnormalities in mobility and measures of locomotion, their types of movement were altered from young animals. Geriatric marmosets had alterations in cardiac function, with significantly increased mean arterial pressures; metabolism, with significantly lower VO 2 ; and suppressed immune function. Further, this study sought to characterize and describe histopathology for both young and geriatric healthy marmosets. Overall this study provides a characterization of health parameters for young and geriatric marmosets which will greatly enhance future aging and interventional testing in marmosets.
American Journal of Primatology
Executive control is a higher-level cognitive function that involves a range of different process... more Executive control is a higher-level cognitive function that involves a range of different processes that are involved in the planning, coordination, execution, and inhibition of responses. Many of the processes associated with executive control, such as response inhibition and mental flexibility, decline with age. Degeneration of white matter architecture is considered to be the one of the key factors underlying cognitive decline associated with aging. Here we investigated how white matter changes of the corpus callosum were related to cognitive aging in common marmosets (Callithrix jacchus). We hypothesized that reduction in myelin thickness, myelin density, and myelin fraction of axonal fibers in the corpus callosum would be associated with performance on a task of executive function in a small sample of geriatric marmosets (n = 4) and young adult marmosets (n = 2). Our results indicated declines in myelin thickness, density, and myelin fraction with age. Considerable variability was detected on these characteristics of myelin and cognitive performance assessed via the detoured reach task. Age-related changes in myelin in Region II of the corpus callosum were predictive of cognitive performance on the detoured reach task. Thus the detoured reach task appears to also measure aspects of corticostriatal function in addition to prefrontal cortical function. Keywords brain aging; cognitive aging; primate models Executive control is a higher-level cognitive function that involves a range of processes that are involved in planning, coordination, execution, and inhibition of responses to stimuli (Glisky, 2007). As such, executive control is believed to play a major role in almost all
Cerebral cortex (New York, N.Y. : 1991), Jan 13, 2018
Area 10, located in the frontal pole, is a unique specialization of the primate cortex. We studie... more Area 10, located in the frontal pole, is a unique specialization of the primate cortex. We studied the cortical connections of area 10 in the New World Cebus monkey, using injections of retrograde tracers in different parts of this area. We found that injections throughout area 10 labeled neurons in a consistent set of areas in the dorsolateral, ventrolateral, orbital, and medial parts of the frontal cortex, superior temporal association cortex, and posterior cingulate/retrosplenial region. However, sites on the midline surface of area 10 received more substantial projections from the temporal lobe, including clear auditory connections, whereas those in more lateral parts received >90% of their afferents from other frontal areas. This difference in anatomical connectivity reflects functional connectivity findings in the human brain. The pattern of connections in Cebus is very similar to that observed in the Old World macaque monkey, despite >40 million years of evolutionary se...
Journal of Comparative Psychology, Jul 1, 2004
Experiments were conducted to investigate which sensory cues are used by brown capuchins (Cebus a... more Experiments were conducted to investigate which sensory cues are used by brown capuchins (Cebus apella) in embedded invertebrate foraging. The importance of visual, olfactory, and acoustic cues in such foraging was determined by presenting subjects with a stimulus log modified to block out given sensory cues. Experiment 1 was designed to investigate whether subjects could locate an invertebrate embedded in wood when only visual, acoustic, or olfactory information was available. Experiments 2 and 3 were designed to investigate extractive foraging behavior when two sensory cues were provided. It was hypothesized that the combination of visual and acoustic information would be necessary for subjects to successfully locate embedded invertebrates. Results indicated that subjects' performance was most successful when both visual and acoustic information was available.
International Journal of Primatology, Dec 1, 1994
... 6, 1994 Sexual Behavior in Brown Capuchins (Cebus ape//a) Kim A. Phillips, ~,2 Irwin S. Berns... more ... 6, 1994 Sexual Behavior in Brown Capuchins (Cebus ape//a) Kim A. Phillips, ~,2 Irwin S. Bernstein, 1 Elizabeth L. Dettmer, 1 Heather Devermann, 1 and Marybeth Powers t Recieved April 26, 1993; accepted June 14, 1993 ... Welker, C., H6hmann, H., and Sch~ifer-Witt, C. (1990). ...
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Papers by Kimberley Phillips