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Hemisphere-Specific Deficits in the Control of Bimanual Movements After Stroke.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Hemisphere-Specific Deficits in the Control of Bimanual Movements After Stroke./
作者:	Varghese, Rini.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	191 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
Contained By:	Dissertations Abstracts International83-03B.
標題:	Neurosciences. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28715932
ISBN:	9798535596990

Hemisphere-Specific Deficits in the Control of Bimanual Movements After Stroke.
Varghese, Rini.

Hemisphere-Specific Deficits in the Control of Bimanual Movements After Stroke. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 191 p.

Source: Dissertations Abstracts International, Volume: 83-03, Section: B.

Thesis (Ph.D.)--University of Southern California, 2021.

This item must not be sold to any third party vendors.

Stroke continues to be the leading cause of adult disability in the US and worldwide, with as many as two-thirds of survivors experiencing some degree of contralesional arm and hand weakness. Conventional rehabilitation practices focus on the recovery of the contralesional arm, but several recent clinical trials investigating the effectiveness of variants of contralesional arm training have reported negative or neutral outcomes. Naturally, efforts to recover and rehabilitate the paretic upper extremity in isolation are of little value if it is not engaged in meaningful functional activities-activities that are predominantly bilateral in nature, requiring the coordinated engagement of both the paretic and non-paretic limbs. One alternative to traditional paretic limb training is bilateral upper extremity training; however, its effectiveness has been shown to vary by the side of hemispheric lesion. Therefore, the current dissertation seeks to characterize hemisphere-specific deficits in the control of bimanual movements after stroke. To do this, I first conducted a series of retrospective observational studies (Chapter 3, 4, 5) of an existing stroke database from a previous phase-IIb clinical trial (Dose Optimization for Stroke Evaluation, ClinicalTrials.gov ID: NCT01749358). Then, I collected data in a prospective experimental study (Chapter 6) to uncover the differences in bimanual coordination observed between individuals with left and right hemisphere stroke.Chapter 3 begins with a retrospective observational analysis in which we studied the factors that influence the spontaneous selection of both hands for bimanual tasks-tasks that would otherwise, in age-similar able-bodied individuals, naturally elicit the use of both hands. To capture spontaneous, task-specific choices, we covertly observed 50 pre-stroke right-handed chronic stroke survivors (25 each of left paresis, and right paresis) and 11 age-similar control adults and recorded their hand use strategies for two pairs of bimanual tasks with distinct demands: one with greater precision requirements (photo-album tasks), and another with greater stabilization requirements (letter-envelope tasks). We found that the probability of choosing a bimanual strategy is greater for those with less severe motor impairment and in those with right paresis. However, the influence of these factors, i.e., impairment severity and side of lesion, on bimanual choice varied based on task demands. In Chapter 4, we further analyze these differences in spontaneous bimanual use by examining the relationship between unimanual performance of the upper extremities in a subset of 42 of the sample of 50 chronic stroke survivors examined in Chapter 3. The purpose of this retrospective analysis was to test the idea that those with right paresis were more likely to use both hands together more because their less-affected left hand would be slower on its own. To do this, we looked at the relationship between the degree of impairment in the contralesional hand, quantified using the Upper Extremity Fugl-Meyer score and the extent of ipsilesional hand deficits, quantified by the distal component of the Wolf Motor Function Test. We found that in those with right paresis, the speed of performance with the ipsilesional hand was proportionally slower to the degree of contralesional impairment. However, this was not the case in those with left paresis. This interaction between ipsilesional hand and side of lesion was observed not only with a measure of contralesional impairment but also contralesional hand function. In Chapter 5, given the well-established role of the CC for bimanual coordination, especially fibers connecting the larger sensorimotor networks such as prefrontal, premotor, and supplementary motor regions, we examine the relationship between the microstructural status of the CC and bimanual performance in chronic stroke survivors (n = 41). We used movement times for two self-initiated and self-paced bimanual tasks (quantified in Chapter 3) to capture bimanual performance. Using publicly available control datasets (n = 52), matched closely for acquisition parameters, including sequence, diffusion gradient strength and number of directions, we also explored the effect of age and stroke on callosal microstructure. We found that callosal microstructure was significantly associated with bimanual performance in chronic stroke survivors such that those with lower callosal FA were slower at completing the bimanual task. Notably, while the primary sensorimotor regions (CC3) showed the strongest relationship with bimanual performance, this was closely followed by the premotor/supplementary motor (CC2) and the prefrontal (CC1) regions. Furthermore, chronic stroke survivors presented with significantly greater loss of callosal fiber orientation (lower mean FA) compared to neurologically intact, age-similar controls, who in turn presented with lower callosal FA compared to younger controls. The effect of age and stroke were observed for all regions of the CC except the splenium. These findings suggest that in chronic stroke survivors with relatively localized lesions, callosal microstructure can be expected to change beyond the primary sensorimotor regions and might impact coordinated performance of self-initiated and cooperative bimanual tasks.Lastly, the purpose of Chapter 6 was to understand the principles of responsibility assignment in a bimanual task and thereby uncover mechanisms underlying the previously observed hemisphere-specific effects of stroke. To do this, I used a prospective experimental design and studied a redundant bimanual task wherein we tested the predictions of a leading theory in motor control, known as the Optimal Feedback Control model (OFC). The OFC model suggests that responsibility assignment is a flexible process such that errors are assigned to and corrected for by the limb that is most likely to produce those errors. In right-handed adults, this is often the less-skilled, non-dominant left limb. The flexibility of this process can be probed by examining corrections made by each limb after they have acquired alternative use-dependent experiences, e.g., if the left limb became more skilled, experiencing fewer errors or if the right limb became less skilled, experiencing more frequent errors. Such is the case of stroke affecting the right side of the body, wherein we would predict that the left limb corrects less while the paretic right limb corrects more for task error. In this prospective study, we tested this prediction in 20 individuals with an intact sensorimotor system, as well as 23 chronic stroke survivors (12 right hemiparesis). Consistent with previous studies, correction gains were asymmetric between the limbs in the non-disabled young control group such that the left limb corrected more than the right limb. Our data also supported our predictions in those with right hemiparesis, but not in those with left hemiparesis. Those with right hemiparesis not only corrected more with their paretic right limb within a trial, but also corrected less with their now more skilled left limb. They also systematically adapted to these errors in a feedforward manner over trials. The extent of correction in stroke survivors did not appear to vary with the degree of motor impairment of the paretic extremity. These findings lead us to conclude that responsibility assignment is not entirely flexible but may be limited to some extent by the hemispheric specialization of motor control processes. Prior to this experiment, I performed an experiment that used an interlimb interference paradigm, motivated by early models of bimanual control. The main findings of this experiment are presented in the Appendix. Collectively, these studies show that mechanisms of deficits in bimanual coordination after stroke are distinct between individuals with left and right hemisphere damage.

ISBN: 9798535596990Subjects--Topical Terms:

588700
Neurosciences.
Subjects--Index Terms:

Bimanual

Hemisphere-Specific Deficits in the Control of Bimanual Movements After Stroke.
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500 $a Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
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502 $a Thesis (Ph.D.)--University of Southern California, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Stroke continues to be the leading cause of adult disability in the US and worldwide, with as many as two-thirds of survivors experiencing some degree of contralesional arm and hand weakness. Conventional rehabilitation practices focus on the recovery of the contralesional arm, but several recent clinical trials investigating the effectiveness of variants of contralesional arm training have reported negative or neutral outcomes. Naturally, efforts to recover and rehabilitate the paretic upper extremity in isolation are of little value if it is not engaged in meaningful functional activities-activities that are predominantly bilateral in nature, requiring the coordinated engagement of both the paretic and non-paretic limbs. One alternative to traditional paretic limb training is bilateral upper extremity training; however, its effectiveness has been shown to vary by the side of hemispheric lesion. Therefore, the current dissertation seeks to characterize hemisphere-specific deficits in the control of bimanual movements after stroke. To do this, I first conducted a series of retrospective observational studies (Chapter 3, 4, 5) of an existing stroke database from a previous phase-IIb clinical trial (Dose Optimization for Stroke Evaluation, ClinicalTrials.gov ID: NCT01749358). Then, I collected data in a prospective experimental study (Chapter 6) to uncover the differences in bimanual coordination observed between individuals with left and right hemisphere stroke.Chapter 3 begins with a retrospective observational analysis in which we studied the factors that influence the spontaneous selection of both hands for bimanual tasks-tasks that would otherwise, in age-similar able-bodied individuals, naturally elicit the use of both hands. To capture spontaneous, task-specific choices, we covertly observed 50 pre-stroke right-handed chronic stroke survivors (25 each of left paresis, and right paresis) and 11 age-similar control adults and recorded their hand use strategies for two pairs of bimanual tasks with distinct demands: one with greater precision requirements (photo-album tasks), and another with greater stabilization requirements (letter-envelope tasks). We found that the probability of choosing a bimanual strategy is greater for those with less severe motor impairment and in those with right paresis. However, the influence of these factors, i.e., impairment severity and side of lesion, on bimanual choice varied based on task demands. In Chapter 4, we further analyze these differences in spontaneous bimanual use by examining the relationship between unimanual performance of the upper extremities in a subset of 42 of the sample of 50 chronic stroke survivors examined in Chapter 3. The purpose of this retrospective analysis was to test the idea that those with right paresis were more likely to use both hands together more because their less-affected left hand would be slower on its own. To do this, we looked at the relationship between the degree of impairment in the contralesional hand, quantified using the Upper Extremity Fugl-Meyer score and the extent of ipsilesional hand deficits, quantified by the distal component of the Wolf Motor Function Test. We found that in those with right paresis, the speed of performance with the ipsilesional hand was proportionally slower to the degree of contralesional impairment. However, this was not the case in those with left paresis. This interaction between ipsilesional hand and side of lesion was observed not only with a measure of contralesional impairment but also contralesional hand function. In Chapter 5, given the well-established role of the CC for bimanual coordination, especially fibers connecting the larger sensorimotor networks such as prefrontal, premotor, and supplementary motor regions, we examine the relationship between the microstructural status of the CC and bimanual performance in chronic stroke survivors (n = 41). We used movement times for two self-initiated and self-paced bimanual tasks (quantified in Chapter 3) to capture bimanual performance. Using publicly available control datasets (n = 52), matched closely for acquisition parameters, including sequence, diffusion gradient strength and number of directions, we also explored the effect of age and stroke on callosal microstructure. We found that callosal microstructure was significantly associated with bimanual performance in chronic stroke survivors such that those with lower callosal FA were slower at completing the bimanual task. Notably, while the primary sensorimotor regions (CC3) showed the strongest relationship with bimanual performance, this was closely followed by the premotor/supplementary motor (CC2) and the prefrontal (CC1) regions. Furthermore, chronic stroke survivors presented with significantly greater loss of callosal fiber orientation (lower mean FA) compared to neurologically intact, age-similar controls, who in turn presented with lower callosal FA compared to younger controls. The effect of age and stroke were observed for all regions of the CC except the splenium. These findings suggest that in chronic stroke survivors with relatively localized lesions, callosal microstructure can be expected to change beyond the primary sensorimotor regions and might impact coordinated performance of self-initiated and cooperative bimanual tasks.Lastly, the purpose of Chapter 6 was to understand the principles of responsibility assignment in a bimanual task and thereby uncover mechanisms underlying the previously observed hemisphere-specific effects of stroke. To do this, I used a prospective experimental design and studied a redundant bimanual task wherein we tested the predictions of a leading theory in motor control, known as the Optimal Feedback Control model (OFC). The OFC model suggests that responsibility assignment is a flexible process such that errors are assigned to and corrected for by the limb that is most likely to produce those errors. In right-handed adults, this is often the less-skilled, non-dominant left limb. The flexibility of this process can be probed by examining corrections made by each limb after they have acquired alternative use-dependent experiences, e.g., if the left limb became more skilled, experiencing fewer errors or if the right limb became less skilled, experiencing more frequent errors. Such is the case of stroke affecting the right side of the body, wherein we would predict that the left limb corrects less while the paretic right limb corrects more for task error. In this prospective study, we tested this prediction in 20 individuals with an intact sensorimotor system, as well as 23 chronic stroke survivors (12 right hemiparesis). Consistent with previous studies, correction gains were asymmetric between the limbs in the non-disabled young control group such that the left limb corrected more than the right limb. Our data also supported our predictions in those with right hemiparesis, but not in those with left hemiparesis. Those with right hemiparesis not only corrected more with their paretic right limb within a trial, but also corrected less with their now more skilled left limb. They also systematically adapted to these errors in a feedforward manner over trials. The extent of correction in stroke survivors did not appear to vary with the degree of motor impairment of the paretic extremity. These findings lead us to conclude that responsibility assignment is not entirely flexible but may be limited to some extent by the hemispheric specialization of motor control processes. Prior to this experiment, I performed an experiment that used an interlimb interference paradigm, motivated by early models of bimanual control. The main findings of this experiment are presented in the Appendix. Collectively, these studies show that mechanisms of deficits in bimanual coordination after stroke are distinct between individuals with left and right hemisphere damage.
520 $a For those with left paresis (right hemisphere stroke), error detection or correction is impaired, and it may be why these individuals do not spontaneously use both hands. Large inter-individual variability might suggest sensitivity to the type of error or different mechanisms for correcting it, however we did not explicitly test this idea in this dissertation. Potential rehabilitation strategies might include accuracy training for these individuals. Conversely, in those with right paresis (left hemisphere stroke), error assignment and adaptation seem to be intact. In fact, extensive experience helps the once-less-skilled left limb to calibrate its forward model. However, these individuals were slower than controls. Therefore, potential rehabilitation approaches might include speed training for these individuals.
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