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Browsing by Subject "physiology"

Now showing 1 - 4 of 4
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    Behavioral differences in sound detection in recently diverged cave and surface forms of Astyanax mexicanus
    (2021) Kistner, Amanda R; Enriquez, Maya S; Michels, Noland O; Mensinger, Allen F
    Astyanax mexicanus, or the Mexican tetra, inhabits both surface streams and cave systems, and has subsequently developed two unique morphologies: a cave morph and a surface morph. Cave morphs of the species have evolved several troglomorphic phenotypes, including vestigial eyes, reduced pigmentation, and increased olfactory and lateral line sensitivity. Interestingly, several satellite populations of surface fish were introduced to a Texas aquifer approximately 100 years ago and, following cave colonization, rapid evolution of various sensory adaptations between the cave and surface populations have been observed. Auditory evoked potential (AEP) data was collected to compare hearing sensitivities between cave and surface satellite populations, and both populations responded to sound presentation up to 4 kHz. However, because AEPs measure action potential summation to screen for frequency sensitivities, behavioral data is needed to determine absolute hearing sensitivity. The current study examines behavioral differences in sound detection between these two populations using reflexive startle behaviors to sound, namely the “C-start” escape response, which has been shown to be a reliable means of determining neurological responses to acoustic stimuli. Based on behavioral audiograms collected on satellite three populations, San Pedro Springs (cave) and Honey Creek (surface) appear to respond more readily to acoustic stimuli and habituate at a similar rate when compared to San Antonio Zoo (surface), which appear to respond less readily and habituate faster. Differences in sound pressure thresholds, as well as stimulus-response latencies between these populations, will be determined through finer volume control and modeling sub-thresholds.
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    Dynamic Flexibility in Infancy: Moment-by-Moment Biobehavioral Organization and Synchrony Across System and Context
    (2022-06) Stallworthy, Isabella
    As humans, our sophisticated interpersonal capacities emerge from neural, biological, and behavioral systems that are intricately coordinated, both internally and with other people. However, research to date has allocated comparatively little focus to the dynamic processes of how social interactions emerge across levels of analysis, especially early in development. Second-person neuroscience (SPN) and dynamic systems approaches together offer an integrative framework for studying the development of social interactions in infancy, through quantifying flexible biobehavioral organization, interactivity within and between people, and dynamic sensitivity to context. This study builds on previous work by using a novel study design that capitalizes on the ubiquity of personal technology and leverages newly adapted methodologies for capturing the dynamic unfolding of real-time, moment-by-moment social processes. The current study quantified continuous heart rate and behavior (~360 observations per system, per person) from 44 mothers and their typically developing infants (M= 9 months) during face-to-face interaction, a perturbation (unexpected series of text messages), and recovery. Aim 1 results revealed a flexible, putative self-organizational structure for the unfolding of both infants’ behavior and their physiology, with relatively less rigid organization associated with more positive social engagement across the entire task. Results from Aim 2 found dynamic, positive linkages between infants’ parasympathetic nervous system activity and their social engagement at the subsequent second, but only while their caregiver was actively attending to them. Lastly, Aim 3 results revealed moment-by-moment parasympathetic synchrony between mothers and infants in the form of a co-regulatory feedback loop. Mothers’ parasympathetic activity positively predicted that of their infant at the subsequent second, a linkage that decreased during the task perturbation and did not fully recover upon reunion. Conversely, infant parasympathetic activity negatively predicted that of their mother at the subsequent second, a linkage that was not sensitive to social context. Together, these findings offer new ways of capturing flexibility in social interactions –through the unfolding of moment-by-moment, flexible midrange organization; cross-system linkages; and asymmetric dyadic synchrony –reflecting both stability and adjustment in the face of changing contexts. Findings from this study contribute to both basic science knowledge and potential targets for monitoring and intervention to better support adaptive social development across the lifespan.
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    Estradiol deficiency impairs satellite cell function and causes muscle weakness via an estrogen receptor alpha mediated mechanism
    (2017-12) Collins, Brittany
    Overall, my dissertation work has shown that estradiol is a critical extrinsic factor in females that regulates muscle stem cell (i.e. satellite cell) and skeletal muscle function (Chapters 3 and 4) and estrogen receptor alpha (ER) is the main receptor estradiol utilizes for these functions (Chapters 3 and 4). I identified that the loss of ovarian hormones resulted in impaired satellite cell functions such as maintenance and self-renewal, while estradiol treatment rescued the detrimental effects on satellite cell maintenance and self-renewal (Chapter 3). Further experiments utilized a transgenic mouse that specifically ablated ER in satellite cells, the results of which indicated that ER is necessary for proper satellite cell function (Chapter 3). In agreement with my work on satellite cells, I identified that ER is necessary for overall skeletal muscle function (Chapter 4). I utilized a transgenic mouse model that deleted ER specifically from skeletal muscle fibers which resulted in impairments in strength, power, and fatiguability of skeletal muscle (Chapter 4). The work of my dissertation highlights a novel mechanism for estradiol and ER in skeletal muscle.
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    Mechanistic links between physiology and spectral reflectance enable pre-visual detection of oak wilt and drought stress
    (Proceedings of the National Academy of Sciences, 2024-02) Sapes, Gerard; Schroeder, Lucy; Scott, Allison; Clark, Isaiah; Juzwik, Jennifer; Montgomery, Rebecca; Guzmán Q., J. Antonio; Cavender-Bares, Jeannine
    Tree mortality due to global change—including range expansion of invasive pests and pathogens—is a paramount threat to forest ecosystems. Oak forests are among the most prevalent and valuable ecosystems both ecologically and economically in the United States. There is increasing interest in monitoring oak decline and death due to both drought and the oak wilt pathogen (Bretziella fagacearum). We combined anatomical and ecophysiological measurements with spectroscopy at leaf, canopy, and airborne levels to enable differentiation of oak wilt and drought, and detection prior to visible symptom appearance. We performed an outdoor potted experiment with Quercus rubra saplings subjected to drought stress and/or artificially inoculated with the pathogen. Models developed from spectral reflectance accurately predicted ecophysiological indicators of oak wilt and drought decline in both potted and field experiments with naturally grown saplings. Both oak wilt and drought resulted in blocked water transport through xylem conduits. However, oak wilt impaired conduits in localized regions of the xylem due to formation of tyloses instead of emboli. The localized tylose formation resulted in more variable canopy photosynthesis and water content in diseased trees than drought-stressed ones. Reflectance signatures of plant photosynthesis, water content and cellular damage detected oak wilt and drought 13 days before visual symptoms appeared. Our results show that leaf spectral reflectance models predict ecophysiological processes relevant to detection and differentiation of disease and drought. Coupling spectral models that detect physiological change with spatial information enhances capacity to differentiate plant stress types such as oak wilt and drought.