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Previous studies have found that the detection of near-threshold stimuli is decreased immediately before movement and throughout movement production. This has been suggested to occur through the use of the internal forward model processing an efferent copy of the motor command and creating a prediction that is used to cancel

Previous studies have found that the detection of near-threshold stimuli is decreased immediately before movement and throughout movement production. This has been suggested to occur through the use of the internal forward model processing an efferent copy of the motor command and creating a prediction that is used to cancel out the resulting sensory feedback. Currently, there are no published accounts of the perception of tactile signals for motor tasks and contexts related to the lips during both speech planning and production. In this study, we measured the responsiveness of the somatosensory system during speech planning using light electrical stimulation below the lower lip by comparing perception during mixed speaking and silent reading conditions. Participants were asked to judge whether a constant near-threshold electrical stimulation (subject-specific intensity, 85% detected at rest) was present during different time points relative to an initial visual cue. In the speaking condition, participants overtly produced target words shown on a computer monitor. In the reading condition, participants read the same target words silently to themselves without any movement or sound. We found that detection of the stimulus was attenuated during speaking conditions while remaining at a constant level close to the perceptual threshold throughout the silent reading condition. Perceptual modulation was most intense during speech production and showed some attenuation just prior to speech production during the planning period of speech. This demonstrates that there is a significant decrease in the responsiveness of the somatosensory system during speech production as well as milliseconds before speech is even produced which has implications for speech disorders such as stuttering and schizophrenia with pronounced deficits in the somatosensory system.
ContributorsMcguffin, Brianna Jean (Author) / Daliri, Ayoub (Thesis director) / Liss, Julie (Committee member) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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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
Description

The aim of this study was to assess whether exposing individuals who are 6-month post-stroke with an upper extremity motor deficit and some form of speech impairment (aphasia and/or apraxia) to upper extremity training utilizing Startle Adjuvant Rehabilitation Therapy (START) would result in improvement in symptoms of speech impairment. It

The aim of this study was to assess whether exposing individuals who are 6-month post-stroke with an upper extremity motor deficit and some form of speech impairment (aphasia and/or apraxia) to upper extremity training utilizing Startle Adjuvant Rehabilitation Therapy (START) would result in improvement in symptoms of speech impairment. It was hypothesized that while scores on Diadochokinetic Rate (a measure of apraxia) and Repetition (a measure of aphasia) would improve by timepoint with START as compared to the Control group, measures of aphasia including Spontaneous Speech, Auditory Verbal Comprehension, and Naming would not be different in scores by timepoint. Subjects were recruited from two separate ongoing studies consisting of three days of similar upper extremity training on certain functional tasks with and without START and the speech assessments utilized were pulled from the Western Aphasia Battery (Revised) and Apraxia Battery for Adults 2nd Edition. It was found that there were no statistically significant differences by timepoint in either condition for any of the speech assessments. This proof-of-concept study is the first to assess whether the StartReact effect, when applied to the upper extremity domain, will translate into measurable improvements in speech impairment despite the lack of any speech training.

ContributorsTesman, Nathan (Author) / Honeycutt, Claire (Thesis director) / Rogalsky, Corianne (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / School of Molecular Sciences (Contributor)
Created2023-05
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Description
Motor skill acquisition, the process by which individuals practice and consolidate
movement to become faster, more accurate and efficient, declines with age. Initial skill acquisition is dominated by cortical structures; however as learning proceeds, literature from
rodents and songbirds suggests that there is a transition away from cortical execution. Recent
evidence indicates that

Motor skill acquisition, the process by which individuals practice and consolidate
movement to become faster, more accurate and efficient, declines with age. Initial skill acquisition is dominated by cortical structures; however as learning proceeds, literature from
rodents and songbirds suggests that there is a transition away from cortical execution. Recent
evidence indicates that the reticulospinal system plays an important role in integration and
retention of learned motor skills. The brainstem has known age-rated deficits including cell
shrinkage & death. Given the role of the reticulospinal system in skill acquisition and older
adult’s poor capacity to learn, it begs the question: are delays in the reticulospinal system
associated with older adult’s poor capacity to learn?
Our objective was to evaluate if delays in the reticulospinal system (measured via the
startle reflex) and corticospinal system (measured via Transcranial Magnetic Stimulation (TMS) are correlated to impairment of motor learning in older adults. We found that individuals with fast startle responses resembling those of younger adults show the most improvement and retention while individuals with delayed startle responses show the least. We also found that there was no relationship between MEP latencies and improvement and retention. Moreover, linear regression analysis indicated that startle onset latency exists within a continuum of learning outcomes suggesting that startle onset latency may be a sensitive measure to predict learning deficits in older adults. As there exists no method to determine an individual’s relative learning capacity, these results open the possibility of startle, which is an easy and inexpensive behavioral measure and can be used to determine learning deficits in older adults to facilitate better dosing during rehabilitation therapy.
ContributorsRangarajan, Vishvak (Author) / Honeycutt, Claire (Thesis director) / Schaefer, Sydney (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
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Description
Motor skill acquisition, the process by which individuals practice and consolidate movement to become faster, more accurate and efficient, declines with age. Initial skill acquisition is dominated by cortical structures; however as learning proceeds, literature from rodents and songbirds suggests that there is a transition away from cortical execution. Recent

Motor skill acquisition, the process by which individuals practice and consolidate movement to become faster, more accurate and efficient, declines with age. Initial skill acquisition is dominated by cortical structures; however as learning proceeds, literature from rodents and songbirds suggests that there is a transition away from cortical execution. Recent evidence indicates that the reticulospinal system plays an important role in integration and retention of learned motor skills. The brainstem has known age-rated deficits including cell shrinkage & death. Given the role of the reticulospinal system in skill acquisition and older adult’s poor capacity to learn, it begs the question: are delays in the reticulospinal system associated with older adult’s poor capacity to learn?
Our objective was to evaluate if delays in the reticulospinal system (measured via the startle reflex) are correlated to impairment of motor learning in older adults. We found that individuals with fast startle responses resembling those of younger adults show the most learning and retention of that learning while individuals with delayed startle responses show the least. Moreover, linear regression analysis indicated that startle onset latency exists within a continuum of learning outcomes suggesting that startle onset latency may be a sensitive measure to predict learning deficits in older adults. As there exists no method to determine an individual’s relative learning capacity, these results open the possibility of startle, which is an easy and inexpensive behavioral measure, being used to predict learning deficits in older adults to facilitate better dosing during rehabilitation therapy.
ContributorsSchreiber, Joseph James (Author) / Honeycutt, Claire (Thesis director) / Schaefer, Sydney (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
The phenomenon known as startReact is the fast, involuntary execution of a planned movement triggered by a startling acoustic stimulus. StartReact has previously been analyzed in simple motor movements such as finger abduction tasks, hand grasp tasks, and elbow extension tasks. More complex movements have also been analyzed, but there

The phenomenon known as startReact is the fast, involuntary execution of a planned movement triggered by a startling acoustic stimulus. StartReact has previously been analyzed in simple motor movements such as finger abduction tasks, hand grasp tasks, and elbow extension tasks. More complex movements have also been analyzed, but there have been limited studies that look into functional complex tasks that require end-point accuracy. The objective of this project was to assess the ability to elicit startReact in tasks that simulate activities of daily living like feeding or picking up a glass of water. We hypothesized that a startReact response would be present in complex functional tasks, but the response would not be as accurate due to the increase in speed. Five subjects performed a simulated feeding task by moving kidney beans from one target to another where the end target changed in diameter as well as, a simulated drinking task where the subject moved a cup full of beads from one target to another. The hypothesis was supported due to a significant difference between no stimulus and stimulus trials for tricep muscle onset time, duration time, and the accuracy parameters of amount of beans dropped and weight in beads dropped. The results coincided with previous studies where subjects compensated for the change in diameter by increasing reaction time as the target diameter size decreased. The data obtained contradicted a previous study in relation to the duration time between the tasks due to our smallest diameter size having a faster duration time in comparison to the other diameter sizes. This study provides preliminary data that could assist researchers and clinicians in improving physical therapy methods for patients with impaired upper extremity motor movements.
ContributorsRiggs, Cassie Rebekah (Author) / Honeycutt, Claire (Thesis director) / Schaefer, Sydney (Committee member) / Harrington Bioengineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12