• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 127
  • 6
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 152
  • 152
  • 59
  • 59
  • 21
  • 20
  • 20
  • 17
  • 14
  • 13
  • 9
  • 6
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

When and where will a target go? A behavioural and electrophysiological study of expectation in primates

de Hemptinne, Coralie 26 August 2008 (has links)
In a rapidly changing visual environment, the delay between perception and action might impair the probability of survival of a prey or the efficiency of a predator. In order to compensate for delays associated with sensory-motor processing, primates often make predictions about future events and initiate anticipatory movements. To prepare an anticipatory movement, an estimation of when and where to a target is likely to move is necessary. Such an internal representation is often termed 'expectation'. The aim of this thesis was to investigate the gradual changes of a subject's expectation at the behavioral and electrophysiological levels. Anticipatory smooth pursuit was used in order to study temporal and directional changes in expectation. We found that temporal uncertainty strongly modulated the latency and the velocity of anticipatory movements suggesting that monkeys could estimate the hazard rate of target motion onset in order to decide when to initiate an anticipatory movement. In addition, we have shown that monkeys could use prior directional information in order to voluntarily initiate anticipatory responses in the direction of expected target motion. This prior directional information significantly affected the latency and velocity of these movements. Finally, we have shown that the majority of recorded supplementary eye field (SEF) neurons encoded expected target motion direction. The presence of a directional cue induced an increase of activity in the preferred direction of the neuron. Moreover, a large sub-population of neurons encoded the direction of future anticipatory movement. These results suggest that the SEF could be involved in the cognitive control of anticipatory pursuit eye movements when prior temporal and directional information is provided.
132

Evaluation of sperm functionality in non-human primates, focussing on sperm capacitation

Mabotha, Luke Allen January 2019 (has links)
Magister Scientiae (Medical Bioscience) - MSc(MBS) / The incidence of male infertility is increasing, with up to 50% of infertile males having “unexplained” (idiopathic) infertility. Newly developed molecular techniques have great value in detecting subtle causes of male infertility, as compared to idiopathic infertility which may be explained by standardizing and optimizing sperm functional and structural tests in non-human primate (NHP) sperm. The aim of the study was to evaluate sperm functionality utilizing the sperm of two NHP species, i.e.1) the rhesus monkey (Macaca mulatta) and 2) the vervet monkey (Chlorocebus aethiops), and further evaluate the effect of physiological media (including commonly used, and newly formulated sperm wash and sperm capacitating media) on NHP sperm functionality. Sperm functionality was evaluated by investigating the following sperm functions i.e.: sperm motility, vitality, acrosome reaction (AR), hyperactivation, and mitochondrial membrane potential (MMP). Sperm functional tests included computer-aided semen analysis (CASA), motility analysis, BrightVit staining for sperm vitality, flourescenin isothiocyanate (FITC)- conjugated peanut agglutinin (PNA) staining for sperm acrosome integrity, induction of hyperactivation by stimulants (sperm preparation media containing capacitating ingredients), and mitochondrial inhibitor (Oligomycin-A) for testing MMP. All functional and structural tests were investigated in both species, except for acrosome integrity, mitochondrial inhibition and functional tests compared over time that could not be successfully completed and investigated in the rhesus species. Motility analysis tests proved that within the vervet species, the use of different physiological media results in statistically significant differences in motility and kinematic parameters over a 1 hour time period. Hyperactivation tests proved that capacitating physiological media produced significantly higher percentages hyperactivation when compared to sperm wash media within the vervet species over a 1 hour time period. Furthermore, within both NHP species, sperm structural analysis (vitality and acrosome integrity) results showed that no significant differences are present when making use of different physiological media over a period of 1 hour incubation. The incubation of vervet sperm with different concentrations of mitochondrial inhibitor, Oligomycin-A (0 μM, 5 μM, and 25 μM), resulted in motility inhibition over a 1 hour incubation period. By the evaluation of these tests it was found that the use of different sperm wash [Human tubal fluid (HTF), Ham‟s F-10® and HD Sperm Wash Plus (HDSWP)] and sperm capacitation media [Human tubal fluid with added caffeine (HTFC) and HD Sperm Capacitating Plus (HDSCP)] resulted in significantly different results within sperm functional tests as compared to sperm structural tests. The study indicates that the composition of media, varying from simple to more complex, used for semen preparation plays an important role in determining NHP sperm functionality. Based on these findings further investigation in larger NHP sample groups and human sperm are required to evaluate the role of certain ingredients in the development of more cost-effective media producing satisfactory results in terms of sperm functionality for artificial reproductive technologies (ART).
133

High field functional magnetic resonance imaging in the awake, behaving primate cortical networks involved in vergence eye movements /

Ward, Matthew K. January 2008 (has links) (PDF)
Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Additional advisors: Frank Amthor, Claudio Busettini, James Cox, Rosalyn Weller. Description based on contents viewed July 27, 2009; title from PDF t.p. Includes bibliographical references (p. 104-113).
134

Mother-infant separation in monkeys

Seay, Billy Mack. January 1962 (has links)
Thesis (M.S.)--University of Wisconsin-Madison, 1962. / Includes bibliographical references (leaves 22-23).
135

Relativní početnost jako kognitivní kompetence u primátů / Relative numerosity discrimination in primates

Moravcová, Anna January 2019 (has links)
This work is focused on numerical competence in primates specifically focusing on relative numerosity, one of the many aspects of these cognitive abilities. Relative numerosity is an ability to discriminate a larger quantity from a smaller amount or smaller quantity from a larger amount and could be classified as one of the easiest numerical competence. In this work I have summarized the present knowledge of numerical competences in primates, which have been so far studied only in a few species of primates, most of them was rhesus macaque (Macaca mulatta) and chimpanzee (Pan troglodytes). In the experimental part I focused on the research of relative numerosity in rhesus macaque (Macaca mulatta). The goal of my work was to find out whether macaques are able to solve the problem of relative abundance with different types of stimuli. Another goal was to find out whether they are able to generalize information about relative abundance and whether they can apply it for new design of the task. The results confirm that macaques possess the ability of relative numerosity and are able to abstract stimuli that are differing in their character. This proves that they are not learning to recognize a particular stimul, but are able to use this numerical skill on any type of stimul. I also found out that...
136

The ductuli efferentes in Macaca mulatta : electron microscopic evaluation of changes after vasectomy

Marsh, Loyal Douglas 01 January 1980 (has links)
After vasectomy, the passage of sperm antigen through the epithelium of the efferent duct in the rhesus macaque probably results in immune complex deposition. Immune complexes can be visualized in the thickened basement by fluorescence microscopy. Subsequent electron microscopic evaluation, with the appearance of electron-dense deposits in the basement membrane of the efferent ducts, substantiates these findings.
137

Cell-type specific cholinergic modulation in anterior cingulate and lateral prefrontal cortices of the rhesus macaque

Tsolias, Alexandra 03 November 2023 (has links)
The lateral prefrontal cortex (LPFC) and the anterior cingulate cortex (ACC) are two key regions of the frontal executive control network. Ascending cholinergic pathways differentially innervate these two functionally distinct cortices to modulate arousal and motivational signaling for higher-order functions. The action of acetylcholine (ACh) in sensory cortices is constrained by layer, anatomical cell type, and subcellular localization of distinct receptors, but little is known about the nature and organization of frontal-cholinergic circuitry in primates. In this dissertation, we characterized the anatomical localization of muscarinic acetylcholine receptors (mAChRs), m1 and m2–the predominant subtypes in the cortex–and their expression profiles on distinct cell types and pathways in ACC and LPFC of the rhesus monkey, using immunohistochemistry, anatomical tract-tracing, whole cell patch-clamp recordings, and single nucleus RNA sequencing. In the first series of studies (Chapter 2), we used immunohistochemistry and high-resolution confocal microscopy to reveal regional differences in m1 and m2 receptor localization on excitatory pyramidal and inhibitory neuron subpopulations and subcellular compartments in ACC (A24) versus LPFC (A46) of adult rhesus monkeys (Macaca mulatta; aged 7-11 yrs; 4 males and 2 females). The ACC exhibited a greater proportion of m2+ inhibitory neurons and a greater density of presynaptic m2+ receptors localized on inhibitory (VGAT+) terminations on pyramidal neurons compared to the LPFC. This result suggests a greater cholinergic suppression of GABAergic neurotransmission in ACC. In a second set of experiments (Chapter 3), we examined the heterogeneity of m1 and m2 laminar expression in functionally distinct ACC areas A24, A25, and A32. These differ in their connections with higher order cortical areas and limbic structures, such as the amygdala (AMY). The density of m1+ and/or m2 expressing (m1+/m2+) pyramidal neurons was significantly greater in A24 compared to A25 and to A32, while A25 exhibited a significantly greater density of m2+VGAT+ terminals. In addition, we examined the substrates for cholinergic modulation of long-range cortico-limbic processing using bidirectional neural tracers to label one specific subtype, the AMY-targeting projection neurons in these ACC areas. Compared to A24 and A32, the limbic ventral A25 had a greater density of m1+/m2+ AMY-targeting pyramidal neurons across upper layers 2-3 and deep layers 5-6, suggesting stronger cholinergic modulation of amygdalar outputs. Lastly (Chapter 4), we assessed the functional effects of cholinergic modulation on excitatory and inhibitory synaptic activity as well as the molecular signatures related to m1 and m2 receptor expression. In experiments using in vitro whole-cell patch-clamp recordings of layer 3 pyramidal neurons in ACC and LPFC, we found that application of the cholinergic agonist carbachol (CCh) significantly decreased the frequency of excitatory postsynaptic currents (EPSCs) to a greater extent in ACC A24 than in LPFC A46. Using single nucleus RNA sequencing, we found that enriched m1 and m2 transcriptional profiles in distinct cell-types and frontal areas (ACC A24 and LPFC A46) had differentially expressed genes associated with down-stream signaling cascades related to synaptic signaling and plasticity. Together, these data reveal the anatomical, functional, and transcriptomic neural substrates of diverse cholinergic modulation of local excitatory and inhibitory circuits and long-range cortico-limbic pathways in functionally-distinct ACC and LPFC frontal areas that are important for cognitive-emotional integration.
138

Early Rearing Experience, Hypothalamic-Pituitary-Adrenal (HPA) Activity, and Serotonin Transporter Genotype: Influences on the Development of Anxiety in Infant Rhesus Monkeys (Macaca mulatta)

Dettmer, Amanda 01 May 2009 (has links)
A gene x environment interaction exists in the expression of anxiety for both human and nonhuman primates, such that individuals who are carriers of the (s) allele of the serotonin transporter genotype ( 5-HTT LPR) and exposed to early life stress are more at risk for exhibiting anxiety. The hypothalamic-pituitary-adrenal (HPA) axis has also been implicated in anxiety disorders but the relationship between early life/genotype, HPA activity, and anxiety is not well understood. Further, studies linking the HPA axis to anxiety have relied on "point" samples (blood and salivary cortisol) which reflect moments in time rather than long-term activity. The purpose of this dissertation was three fold: (1) to examine anxious behavior in monkeys with different 5-HTT LPR genotypes and rearing environments across the first two years of life, (2) to compare long-term HPA activity (as measured with hair cortisol) with acute HPA activity (as measured with salivary cortisol) in the same period, and (3) to determine which measure of HPA activity predicts anxiety and/or mediates the rearing/genotype influences on anxious behavior. Infant rhesus monkeys ( Macaca mulatta , N=61) were mother-peer-reared (MPR, n=21), peer-reared (PR, n=20), or surrogate-peer-reared (SPR, n=20) for 8 months, then all relocated into a large social housing situation for the next 18 months. Monkeys were genotyped for 5-HTT LPR and hair and saliva samples were collected for cortisol analysis at months 6, 12, 18, and 24. Behavior was recorded twice per week per subject from 2-24 months and analyzed for the duration of anxiety, social play, and grooming. Regression analysis established predictors of these behaviors. Rearing condition and sex were significant predictors of anxiety across the two years, and HPA activity added significant predictive power in the first six months only. Mediation of the rearing/anxiety relationship by the HPA axis was not evident. Interestingly, hair (but not salivary) cortisol early in life was positively correlated with later anxious behavior. These findings demonstrate the detrimental effects of adverse early life experience on behavioral development and shed light on the interplay between environment, adrenocortical activity, and anxiety. They further demonstrate the usefulness of a long-term measure of HPA activity in predicting later behavior.
139

Variation in the m-Opioid Receptor (OPRM1) and Offspring Sex are Associated with Maternal Behavior in Rhesus Macaques (Macaca mulatta)

Baron, Zachary 16 December 2022 (has links)
A m-opioid receptor (OPRM1) single-nucleotide-polymorphism, found in both humans and rhesus macaques mediates the mother-infant attachment bond. Because mothers treat their sons and daughters differently, it is somewhat surprising that the role of infant sex has not been assessed in the context of a maternal-OPRM1-genotype-by-infant-sex interaction. The present study investigates the effect of maternal-OPRM1-genotype and infant sex on mother-infant behaviors. Over the first six months of offspring life, mother-infant behavioral data assessing attachment quality was collected twice weekly from a large number of rhesus monkey mother-infant pairs (N=161 dyads; n=64 female infants, n=97 male infants). Mothers were genotyped for OPRM1 variation. Factor analysis of the observed behaviors showed two factors: Attachment (maternal-infant cradling, rejections, and infant approaches and leaves), and Maternal Restraints (mother restrains infant, preventing exploration). Further analyses showed a two-way, maternal-genotype-by-infant-sex interaction for both factors. For Attachment, mothers with the CC genotype cradled and restrained (Maternal Restraints) their female infants more and rejected them less, when compared to female infants of CG mothers. Perhaps as a consequence, female infants of CC genotype mothers approached and left their mothers less often, when compared to female infants of CG mothers, likely an indication that female infants from mothers with CG genotype play a greater role in maintaining the mother-infant bond than do female infants from CC genotype mothers. This finding may also indicate a more secure attachment in infants from CC genotype mothers. Unlike female infants, on average, the mother-infant relationship of dyads with a male infant was largely undifferentiated by maternal genotype. These findings suggest that, in contrast to female infants from CG mothers, CC mothers and their female infants appear to have a closer mother-infant relationship which may portend close life-long bonds, as mothers and female offspring remain together throughout life. Male offspring appear to have a more aloof mother-infant bond regardless of OPRM1-genotype. The results of this study indicate that maternal-OPRM1 variation mediates mother-infant attachment behaviors for female infants and has less effect for male infants. This suggests that offspring sex should be included in studies investigating the effect of maternal-OPRM1 genotype on the mother-infant attachment relationship.
140

The Mechanical Environment of Pregnancy: Characterizing the Material Remodeling of Primate Reproductive Tissues

Fang, Shuyang January 2023 (has links)
All human lives start with pregnancy. A pathological pregnancy can be physically, mentally, and financially detrimental to newborns and families. Preterm labor and birth (PTB) is one of the most serious pathological conditions associated with pregnancy. PTB affects 10% of global births and is the leading cause of death in children under five years of age. Multiple etiologies are identified for causing PTB and three major reproductive tissues are involved: the uterus, the cervix, and the feto–maternal interface. Throughout pregnancy, these reproductive tissues change in response to various signals, a process called remodeling. Timely and appropriate remodeling of these tissues is needed for a healthy pregnancy. One central element of remodeling is a change in tissues’ mechanical properties, the focus of this work. This dissertation investigates the mechanical environment of pregnancy by characterizing the remodeling of three reproductive tissues of primates (humans and Rhesus macaque monkeys) and computationally simulating pregnancy physiology. I combine comprehensive mechanical testing with digital image correlation (DIC) to capture the material behavior of reproductive tissues, characterize the architecture of these tissues’ fiber networks by optical coherence tomography (OCT), implement a microstructurally-inspired constitutive mate- rial model, conduct inverse finite element analysis (IFEA) to quantify observed remodeling, and finally use finite element analysis (FEA) to simulate pregnancy anatomy and physiology. Results presented here demonstrate that the non-human primate (NHP) cervix, human uterus, and NHP feto–maternal interface all undergo remodeling during pregnancy and experience com- plex stress conditions. In general, the NHP cervix becomes softer and more extensible, with distinct stages. While the ground substance compressibility stays approximately the same throughout gestation, the fiber network steadily becomes more extensible, though rapidly becomes less stiff and more dispersed during the second trimester. The human uterus late in gestation is softer and more extensible compared to its NP state; most of its remodeling involves changes to fiber network extensibility and architecture. The NHP feto–maternal interface adhesion strength reaches a peak early in the third trimester. Lastly, I generated preliminary subject-specific finite element models of NHP by using a workflow developed for human data. By doing this, the complex stress and stretch conditions that reproductive tissues undergo during pregnancy can be visualized. Future work advancing our understanding of pregnancy and women’s health should include the characterization of the time-dependent properties of reproductive tissues, investigation of the relationship between quantitative ultrasound measurements and tissues’ mechanical properties, and improvements to the current FEA workflow.

Page generated in 0.0405 seconds