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Can Startle Elicit Sequential Movements in Highly Trained Individuals?

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Most daily living tasks consist of pairing a series of sequential movements, e.g., reaching to a cup, grabbing the cup, lifting and returning the cup to your mouth. The process by which we control and mediate the smooth progression of these tasks is not well understood. One method which we…

Most daily living tasks consist of pairing a series of sequential movements, e.g., reaching to a cup, grabbing the cup, lifting and returning the cup to your mouth. The process by which we control and mediate the smooth progression of these tasks is not well understood. One method which we can use to further evaluate these motions is known as Startle Evoked Movements (SEM). SEM is an established technique to probe the motor learning and planning processes by detecting muscle activation of the sternocleidomastoid muscles of the neck prior to 120ms after a startling stimulus is presented. If activation of these muscles was detected following a stimulus in the 120ms window, the movement is classified as Startle+ whereas if no sternocleidomastoid activation is detected after a stimulus in the allotted time the movement is considered Startle-. For a movement to be considered SEM, the activation of movements for Startle+ trials must be faster than the activation of Startle- trials. The objective of this study was to evaluate the effect that expertise has on sequential movements as well as determining if startle can distinguish when the consolidation of actions, known as chunking, has occurred. We hypothesized that SEM could distinguish words that were solidified or chunked. Specifically, SEM would be present when expert typists were asked to type a common word but not during uncommon letter combinations. The results from this study indicated that the only word that was susceptible to SEM, where Startle+ trials were initiated faster than Startle-, was an uncommon task "HET" while the common words "AND" and "THE" were not. Additionally, the evaluation of the differences between each keystroke for common and uncommon words showed that Startle was unable to distinguish differences in motor chunking between Startle+ and Startle- trials. Explanations into why these results were observed could be related to hand dominance in expert typists. No proper research has been conducted to evaluate the susceptibility of the non-dominant hand's fingers to SEM, and the results of future studies into this as well as the results from this study can impact our understanding of sequential movements.
ContributorsMieth, Justin Richard (Author) / Honeycutt, Claire (Thesis director) / Santello, Marco (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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Startle-evoked movement in multi-jointed, two-dimensional reaching tasks

Description
Previous research has shown that a loud acoustic stimulus can trigger an individual's prepared movement plan. This movement response is referred to as a startle-evoked movement (SEM). SEM has been observed in the stroke survivor population where results have shown that SEM enhances single joint movements that are usually performed…

Previous research has shown that a loud acoustic stimulus can trigger an individual's prepared movement plan. This movement response is referred to as a startle-evoked movement (SEM). SEM has been observed in the stroke survivor population where results have shown that SEM enhances single joint movements that are usually performed with difficulty. While the presence of SEM in the stroke survivor population advances scientific understanding of movement capabilities following a stroke, published studies using the SEM phenomenon only examined one joint. The ability of SEM to generate multi-jointed movements is understudied and consequently limits SEM as a potential therapy tool. In order to apply SEM as a therapy tool however, the biomechanics of the arm in multi-jointed movement planning and execution must be better understood. Thus, the objective of our study was to evaluate if SEM could elicit multi-joint reaching movements that were accurate in an unrestrained, two-dimensional workspace. Data was collected from ten subjects with no previous neck, arm, or brain injury. Each subject performed a reaching task to five Targets that were equally spaced in a semi-circle to create a two-dimensional workspace. The subject reached to each Target following a sequence of two non-startling acoustic stimuli cues: "Get Ready" and "Go". A loud acoustic stimuli was randomly substituted for the "Go" cue. We hypothesized that SEM is accessible and accurate for unrestricted multi-jointed reaching tasks in a functional workspace and is therefore independent of movement direction. Our results found that SEM is possible in all five Target directions. The probability of evoking SEM and the movement kinematics (i.e. total movement time, linear deviation, average velocity) to each Target are not statistically different. Thus, we conclude that SEM is possible in a functional workspace and is not dependent on where arm stability is maximized. Moreover, coordinated preparation and storage of a multi-jointed movement is indeed possible.
ContributorsOssanna, Meilin Ryan (Author) / Honeycutt, Claire (Thesis director) / Schaefer, Sydney (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12

DTI indices on Frontotemporal Dementia & Alzheimer’s Disease

Description

Alzheimer’s disease (AD) and Frontotemporal lobe dementia (FTLD) are types of dementia that have distinct differences. To help identify some of the neural differences, researchers use diffusion tensor imaging (DTI) techniques to assist with diagnosing patients and track progression over time. The major objective of this experiment was to use…

Alzheimer’s disease (AD) and Frontotemporal lobe dementia (FTLD) are types of dementia that have distinct differences. To help identify some of the neural differences, researchers use diffusion tensor imaging (DTI) techniques to assist with diagnosing patients and track progression over time. The major objective of this experiment was to use the advanced diffusion tensor imaging techniques of Fractional Anisotropy (FA) and Free water (FW) to help differentiate between AD and FTLD neurodegeneration. The scope of this experiment was to examine literature research on AD and FTLD by gathering the mean values of (FA) and (FW) to identify diffusivity susceptibility in the specific brain regions of the Uncinate Fasciculus (UF) and the Superior Temporal Gyrus (STG). The methods used were the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and the Frontotemporal Lobe Degenerative Neuroimaging Initiative (FTLD): These data repositories provide researchers with study data to define the progression of AD and FTLD. Next, an imaging analysis was used to calculate the average FA and FW through each slice of the brain regions UF and STG in standard space. Then FreeSurfer segmented Superior Temporal Gyrus and the JHU ICBM Atlas of the Uncinate Fasciculus were used as a set of tools for analysis and visualization of structural and functional brain imaging data for processing the cross-sectional and longitudinal data. We calculated 95% Confidence intervals for mean FW and FA at each slice and direction across 21 participants within each dementia group to determine regions of overlap and nonoverlap. Results indicated that for the FA and FW graphs in the x and z directions among UF and STG regions, there were more non-overlap regions between the AD and FTLD in the FW graphs across x and z-directions in particular the UF. Our results indicate that there may be concomitant decline in white and gray matter regions in dementia, and FW may be more sensitive detecting AD related neurodegeneration in the UF and STG regions.
ContributorsMalone, Joshua (Author) / Ofori, Edward (Thesis director) / Schaefer, Sydney (Committee member) / Barrett, The Honors College (Contributor) / College of Health Solutions (Contributor)
Created2022-05