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ItemGrasp Posture Variability Leads to Greater Ipsilateral Sensorimotor Beta Activation during Prosthesis Use Data(Georgia Institute of Technology, 2022) Alterman, Bennett L. ; Ali, Saif ; Keeton, Emily ; Binkley, Katrina ; Hendrix, William ; Lee, Perry J. ; Johnson, John T. ; Wang, Shuo ; Kling, James ; Gale, Mary Kate ; Wheaton, Lewis A.
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ItemVisual encoding of tool-object interactions(Georgia Institute of Technology, 2021) Bayani, Kristel ; Natraj, Nikhilesh ; Gale, Mary Kate ; Temples, Danielle ; Atawala, Neel ; Wheaton, Lewis A.Tools and objects are associated with numerous action possibilities that are reduced depending on the task-related internal and external constraints presented to the observer. Action hierarchies propose that goals represent higher levels of the hierarchy while kinematic patterns represent lower levels of the hierarchy. Prior work suggests that tool-object perception is heavily influenced by grasp and action context. The current study sought to evaluate whether the presence of action hierarchy can be perceptually identified using eye tracking during tool-object observation. We hypothesize that gaze patterns will reveal a perceptual hierarchy based on the observed task context and grasp constraints. Participants viewed tool-objects scenes with two types of constraints: task-context and grasp constraints. Task-context constraints consisted of correct (e.g., frying pan-spatula) and incorrect tool-object pairings (e.g., stapler-spatula). Grasp constraints involved modified tool orientations, which requires participants to understand how initially awkward grasp postures can help achieve the task. The visual scene contained three areas of interests (AOIs): the object, the functional tool-end (e.g., spoon handle), and the manipulative tool-end (e.g., spoon bowl). Results revealed two distinct processes based on stimuli constraints. Goal-oriented encoding, the attentional bias towards the object and manipulative tool-end, was demonstrated when grasp did not lead to meaningful tool-use. In images where grasp postures were critical to action performance, attentional bias was primarily between the object and functional tool-end, which suggests means-related encoding of the graspable properties of the object. This study expands from previous work and demonstrates a flexible constraint hierarchy depending on the observed task constraints.
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ItemAlpha-Band Activity in Parietofrontal Cortex Predicts Future Availability of Vibrotactile Feedback in Prosthesis Use(Georgia Institute of Technology, 2021) Johnson, John T. ; Gavetti De Mari, Daniele ; Doherty, Harper ; Hammond III, Frank L. ; Wheaton, Lewis A.Prosthesis disuse and abandonment is an ongoing issue in upper-limb amputation. In addition to lost structural and motor function, amputation also results in decreased task-specific sensory information. One proposed remedy is augmenting somatosensory information using vibrotactile feedback to provide tactile feedback of grasping objects. While the role of frontal and parietal areas in motor tasks is well established, the neural and kinematic effects of this augmented vibrotactile feedback remain in question. In this study, we sought to understand the neurobehavioral effects of providing augmented feedback during a reach-grasp -transport task. Ten persons with sound limbs performed a motor task while wearing a prosthesis simulator with and without vibrotactile feedback. We hypothesized that providing vibrotactile feedback during prosthesis use would increase activity in frontal and parie tal areas and improve grasp-related behavior. Results show that anticipation of upcoming vibrotactile feedback may be encoded in motor and parietal areas during the reach-to-grasp phase of the task. While grasp aperture is unaffected by vibrotactile feedback, the availability of vibrotactile feedback does lead to a reduction in velocity during object transport. These results help shed light on how engineered feedback is utilized by prostheses users and provide methodologies for further assessment in advanced prosthetics research.
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ItemStonetool Study Dataset(Georgia Institute of Technology, 2021) Topping, Kristel ; Wheaton, Lewis A. ; Stout, Dietrich ; Pargeter, JustinStone tool making is a unique human motor skill dating back to the Paleolithic. It provides the earliest evidence of complex motor skills and social learning. Learning to intentionally shape a stone into a functional tool is thought to rely on the interaction of action observation and individual practice to support motor skill acquisition, but the emergence of adaptive and efficient perceptual processes during the observational learning of such a novel motor skill are not well understood. By examining eye movements and motor skills, the current study sought to evaluate the relationship between perceptual and motor processes related to approximately 90 hours of training on stone tool making. Participants’ (n = 11) gaze and motor performance were assessed at three different training time points: naïve (0 hours of training), post 1 (50 hours of training), post 2 (~90 hours of training). Gaze patterns reveal a transition from high gaze variability during initial observation to lower gaze variability after training. Furthermore, perceptual changes were strongly associated with motor performance improvement suggesting a coupling of perceptual and motor processes during motor learning, in order to attend to the technologically informative aspects of the tool making task. The complex emergence of perceptual-motor coupling in this study emphasizes the importance of naturalistic skill learning studies to understand real-world perceptual-motor interactions and technological skill development. This study also highlights “evolutionary neuroscience” methods for reliably reconstructing ancient motor-skill processes from archaeological evidence.
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ItemPartial-Hand Prosthesis Users Show Improved Reach-to-Grasp Behaviour Compared to Transradial Prosthesis Users with Increased Task Complexity(Georgia Institute of Technology, 2021) Wheaton, Lewis A. ; Alterman, Bennett L. ; Keeton, Emily ; Ali, Saif ; Binkley, Katrina ; Hendrix, William ; Lee, Perry J. ; Wang, Shuo ; Johnson, John T.Purpose: Approaches to improve outcomes after upper-extremity amputation remain poorly understood. Different levels of amputation may affect prosthetic device acceptance, function, and use. Examining differences in behavioural and functional performance for different levels of prosthesis use may provide vital information about unique motor control challenges across levels of amputation. Materials and methods: Participants without amputation completed simple and complex goal-directed reach-to-grasp motor actions using either a transradial or partial-hand prosthesis simulator. We hypothesised that participants using a partial-hand device would show greater functional adaptation compared to participants using a transradial device, measured by (1) lower movement duration, (2) lower reach duration, (3) higher reach peak velocity, and (4) lower placement error. Second, we hypothesised that increased task complexity would lead to greater functional adaptation, particularly in partial-hand users. Results: In the complex task, partial-hand users demonstrated variable grasp approaches, an effect not seen in the simple task or in transradial users. Partial-hand users showed significantly higher reach peak velocities compared to transradial users, regardless of grasp strategy in the complex but not the simple task. All groups showed decreases in movement duration over time in the complex task, but only partial-hand users improved in the simple task. Conclusion: There is a gap in our understanding of how people adapt to amputations of different levels. This work clarifies how device and environmental constraints contribute to unique action outcomes, and influence motor learning, which is crucial for optimising rehabilitation.
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ItemNeurobehavioral data for novel behavioral indicator of explicit awareness dataset(Georgia Institute of Technology, 2017-03-26) Wheaton, Lewis A. ; Lawson, Regan R. ; Gayle, Jordan O.Deficits in sequential motor learning have been observed in many patient populations. Having an understanding of the individual neural progression associated with sequential learning in healthy individuals may provide valuable insights for effective interventions with these patients. Due to individual variability in motor skill acquisition, the temporal course of such learning will be vary, suggesting a need for a more individualized approach. Knowing when a subject becomes aware of movement patterns may provide a marker with which to identify each individual's learning time course. To avoid interfering with the incidental nature of discovery during learning, such an indicator requires an indirect, behaviorally-based approach. In Part I, our study aimed to identify a reliable behavioral indicator predictive of the presence of incidental explicit awareness in a sequential motor learning task. Part II, utilized the predictive indicator and EEG to provide neural validation of perceptual processing changes temporally correlated with the indicator. Results of Part I provide a reliable predictive indicator for the timing of explicit awareness development. Results from Part II demonstrates strong classification reliability, as well as a significant neural correlation with behavior for subjects developing awareness (EXP), not observed with subjects without awareness (NOEXP). Additionally, a temporal correlation of peak activation between neural regions was noted over frontoparietal regions, suggesting that the incidental discovery of motor patterns may involve a facilitative network during awareness development. The proposed indicator provides a tool in which to further examine potential impacts of awareness associated with incidental, or exploratory, motor learning, while the individual nature of the indicator provides a tool for monitoring progress in rehabilitative, exploratory motor learning paradigms.
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ItemKarenia brevis allelopathy compromises the lipidome, membrane integrity, and photosynthesis of competitors (dataset)(Georgia Institute of Technology, 2015-12-17) Poulin, R. X. ; Kubanek, JuliaThe attached data files underlie the forthcoming publication, "Karenia brevis allelopathy compromises the lipidome, membrane integrity, and photosynthesis of competitors".
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ItemYou are what you eat: A combined metabolomics – bioassay approach to understanding prey responses to chemical cues produced by predators fed different diets dataset(Georgia Institute of Technology, 2015-09-09) Weissburg, Marc J. ; Poulin, R.X. ; Kubanek, Julia
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ItemPeer J Consumption Data(Georgia Institute of Technology, 2015-07-22) Weissburg, Marc J. ; Beauvais, JeffreyThe data file contains the results of predation experiments on oyster spat by mud crabs in the presence of chemical cues produced by blue crabs fed differing amounts of mud crabs and placed different distances away. The treatment variables and levels consist of: Distance (0.25m, 0.5m, 1m, 1.5m, or 2m); Diet (High [H], Low [L], or Control [C]); and, Time (24, 48 hours). Date of experiment also is included. The measurement variables consist of Total Number Eaten, and Proportion Eaten Outside Refuge.
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ItemComputational analyses of gene expression profiles of ovarian and pancreatic cancer(Georgia Institute of Technology, 2013-07-16) Lili, LoukiaCancer is a devastating disease for human society with thousands of deaths and estimated new cases every year around the globe. Intensive research efforts on understanding the disease progression and determining effective diagnostics and therapeutics have been employed for over one hundred years. Throughout this time, and in particular during the last two decades, computational-based methods have gained increasing importance in cancer biology research by providing significant advantages in the analysis and interpretation of high-throughput data at the molecular and genomic levels. More specifically, after completion of the Human Genome Project in 2003, and with the Cancer Human Genome Project underway, high-throughput biological assays (e.g., microarray chips, next generation sequencing machines) have supplied researchers thousands of measurements per experimental sample. The massive amount of related data has oftentimes been challenging to interpret and translate, particularly in cancer biology and therapeutics. This thesis reports the results of three independent studies in which high-throughput gene expression is computationally analyzed to address longstanding issues in cancer biology. Two of the studies utilize data from ovarian cancer patients while the third involves data collected from pancreatic cancer patients. In Chapter 1, I address the importance of personalized profiling in pancreatic cancer ; in Chapter 2 the role of cancer stroma in the progression of ovarian cancer and in Chapter 3 evidence for the role of epithelial-to-mesenchymal transition (EMT) in ovarian cancer metastasis. More specifically, Chapter 1 emphasizes the power of personalized molecular profiling in unmasking unique gene expression signatures that correspond to each individual patient. These individual expression patterns (individual profiling), which may be overlooked by the traditional methods of gene signatures enriched in groups of afflicted individuals (group profiling), can provide valuable information for more successful targeted therapies. In order to address this issue in pancreatic cancer, comparisons of the most significantly differentially expressed genes and functional pathways were performed between cancer and control patient samples as determined by group vs. personalized analyses. There was little to no overlap between genes/pathways identified by group analyses relative to those identified by personalized analyses. These results indicated that personalized and not group molecular profiling is the most appropriate approach for the identification of putative candidates for targeted gene therapy of pancreatic and perhaps other cancers with heterogeneous molecular etiology. Chapter 2, also with strong implications on personalized molecular profiling, unveils the functional variability of the tumor microenvironment among ovarian cancer patients. The purpose of this study was to investigate the process of microenvironmental stroma activation in human ovarian cancer by molecular analysis of matched sets of cancer and surrounding stroma tissues from individual patients. Expression patterns of genes encoding signaling molecules and compatible receptors in the cancer stroma and cancer epithelia samples indicated the existence of two sub-groups of cancer stroma with different propensities to support tumor growth. These results demonstrated that functionally significant variability exists among ovarian cancer patients in the ability of the microenvironment to modulate cancer development. Chapter 3 aims to uncover the molecular mechanisms that underlie the metastatic process with the hope that such knowledge may lead to more effective therapeutic treatments. For this purpose, pathological and molecular analyses were conducted in 14 matched sets of primary and metastatic samples from late staged ovarian cancer patients. Pathological examination revealed no morphological differences between any of the primary and metastatic samples. In contrast, gene expression analyses identified two distinct groups of patient samples. One group displayed essentially identical expression patterns to primary samples isolated from the same patients. The second group displayed expression patterns significantly different from primary samples isolated from the same patients. Predominant among the differentially expressed genes characterizing this second class of metastatic samples were genes previously associated with epithelial-to-mesenchymal transtion (EMT). These results supported a role of EMT in at least some ovarian cancer metastases and demonstrated that indistinguishable morphologies between primary and metastatic cancer samples is not sufficient evidence to negate the role of EMT in the metastatic process.