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Exploring developmental mechanisms and function of Drosophila motoneuron dendrites with targeted genetic manipulation of Dscam

Description

Specific dendritic morphologies are a hallmark of neuronal identity, circuit assembly, and behaviorally relevant function. Despite the importance of dendrites in brain health and disease, the functional consequences of dendritic shape remain largely unknown. This dissertation addresses two fundamental and interrelated aspects of dendrite neurobiology. First, by utilizing the genetic…

Specific dendritic morphologies are a hallmark of neuronal identity, circuit assembly, and behaviorally relevant function. Despite the importance of dendrites in brain health and disease, the functional consequences of dendritic shape remain largely unknown. This dissertation addresses two fundamental and interrelated aspects of dendrite neurobiology. First, by utilizing the genetic power of Drosophila melanogaster, these studies assess the developmental mechanisms underlying single neuron morphology, and subsequently investigate the functional and behavioral consequences resulting from developmental irregularity. Significant insights into the molecular mechanisms that contribute to dendrite development come from studies of Down syndrome cell adhesion molecule (Dscam). While these findings have been garnered primarily from sensory neurons whose arbors innervate a two-dimensional plane, it is likely that the principles apply in three-dimensional central neurons that provide the structural substrate for synaptic input and neural circuit formation. As such, this dissertation supports the hypothesis that neuron type impacts the realization of Dscam function. In fact, in Drosophila motoneurons, Dscam serves a previously unknown cell-autonomous function in dendrite growth. Dscam manipulations produced a range of dendritic phenotypes with alteration in branch number and length. Subsequent experiments exploited the dendritic alterations produced by Dscam manipulations in order to correlate dendritic structure with the suggested function of these neurons. These data indicate that basic motoneuron function and behavior are maintained even in the absence of all adult dendrites within the same neuron. By contrast, dendrites are required for adjusting motoneuron responses to specific challenging behavioral requirements. Here, I establish a direct link between dendritic structure and neuronal function at the level of the single cell, thus defining the structural substrates necessary for conferring various aspects of functional motor output. Taken together, information gathered from these studies can inform the quest in deciphering how complex cell morphologies and networks form and are precisely linked to their function.

ContributorsHutchinson, Katie Marie (Author) / Duch, Carsten (Thesis advisor) / Neisewander, Janet (Thesis advisor) / Newfeld, Stuart (Committee member) / Smith, Brian (Committee member) / Orchinik, Miles (Committee member) / Arizona State University (Publisher)

Created2013

Effects of an acute bout of aerobic exercise on motor performance, executive function and intrinsic motivation in adolescents and young adults with Down syndrome

Description

The benefits of exercise have been recommended in typical and other special populations. However, the evidence for persons with Down syndrome (DS) is still limited. This study was aimed at investigating the impact of an acute bout of aerobic exercise intervention on motor performance, executive function and intrinsic motivation in…

The benefits of exercise have been recommended in typical and other special populations. However, the evidence for persons with Down syndrome (DS) is still limited. This study was aimed at investigating the impact of an acute bout of aerobic exercise intervention on motor performance, executive function and intrinsic motivation in adolescents and young adults with DS. Ten participants with DS were assigned to an exercise group, who walked on a incremental treadmill protocol for 20 minutes. The exercise intensity was achieved at 66% of their predicted maximum heart rate. Another ten participants with DS were assigned to an attentional control group, who watched a video for 20 minutes. Measures of fine manual dexterity (e.g., Purdue Pegboard test), manual force production (e.g., grip strength test), processing speed (e.g., visual choice reaction time test), verbal processing (e.g., verbal fluency test), attention shifting ability (e.g., The Dimensional Card sorting test), and inhibitory control (e.g., Knock and Tap test) were tested pre and post intervention. An intrinsic motivation scale (e.g., enjoyment and effort) was conducted after the intervention. First, results showed participants significantly improved their performance in manual force production and Knock and Tap Test after the exercise intervention. While it has been proposed that exercise increases arousal status, neurotransmitters, or cerebral vasculature, the exact mechanisms in persons with DS are still unknown. However, our results showed that after treadmill walking, motor and cognitive improvements can be found in individuals with DS, even in a single exercise session. In addition, participants reported higher scores in enjoyment after video viewing than exercise, which may a result from musical effect or too much emphasis on external rewards in their early participation in exercise. These may imply that participants had low intrinsic motivation to an active lifestyle. Further, scores in effort were significantly higher after exercise than video viewing, which indicated their capabilities to perceive their physical exertion. However, other motivational regulations (e.g., introjected and identified regulations) have shown the relationship with exercise behavior in this population. Thus, further study should consider divergent motivational factors in order to implement an effective exercise program.

ContributorsChen, Chih-Chia (Author) / Ringenbach, Shannon D.R. (Thesis advisor) / Crews, Debra (Committee member) / Kulinna, Pamela (Committee member) / Amazeen, Eric (Committee member) / Arizona State University (Publisher)

Created2013

Assisted Cycling Therapy Improves Self-Efficacy and Exercise Perception in Older Adults with Down Syndrome

Description

The aim of this study was to examine the effects of Assisted Cycle Therapy (ACT) on self-efficacy and exercise perception in older adults with Down syndrome (DS) after a three times a week for 8 weeks intervention. Thirteen participants were in the ACT group in which a motor assisted their…

The aim of this study was to examine the effects of Assisted Cycle Therapy (ACT) on self-efficacy and exercise perception in older adults with Down syndrome (DS) after a three times a week for 8 weeks intervention. Thirteen participants were in the ACT group in which a motor assisted their cycling to be performed at least 30% faster than voluntary cycling (VC), 11 participants were in the voluntary cycling group and two participants were in the no cycling (NC) group. The results showed that both exercise groups (i.e., ACT and VC) improved in their self-efficacy after the 8 week intervention. In addition, exercise perception improved following ACT and not VC or NC. Our results are discussed with respect to their future implications for exercise in the DS population. It might be that the yielded results were due to differences in effort required by each intervention group as well as the neurotrophic factors that occur when muscle contractions create synaptic connections resulting in improvement in cognition and feelings of satisfaction. In the future, research should focus on the psychological factors such as social accountability and peer interaction as they relate to ACT and physical activity in person's with DS.

ContributorsTucker, Kori Ann (Author) / Ringenbach, Shannon (Thesis director) / Arnold, Nathaniel (Committee member) / Holzapfel, Simon (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)

Created2018-05

The Acute Effects of Resistance Training and Assisted Cycling Therapy (Act) on Cognitive Function and Enjoyment of Adults With Down Syndrome: A Pilot Study

Description

Background: Down syndrome is the leading genetic cause of intellectual disabilities. Executive function is an area that people with Down syndrome have a diminished capacity compared to those in the general population. In recent years it has been determined that acute and chronic exercise has a small but positive effect…

Background: Down syndrome is the leading genetic cause of intellectual disabilities. Executive function is an area that people with Down syndrome have a diminished capacity compared to those in the general population. In recent years it has been determined that acute and chronic exercise has a small but positive effect on measures of executive function in typically developed individuals. The effect has been recorded separately in both aerobic, high-rate passive and resistance exercises in adolescents with DS but has not been compared between exercise types in adults with DS. Methods: A randomized crossover study was utilized to determine the effect of resistance exercise, assisted cycling therapy, and no exercise on executive function and enjoyment in adults with Down syndrome. Resistance Training (RT)- participants completed a total of 16- repetitions of approximately 75% of a 1-RM in the leg press, chest press, seated row, and latissimus pulldown. ACT- participants completed 30-minutes of cycling at 35% above voluntary (e.g., self-selected pace) rate. No-Training (NT)- participants spent 35-minutes playing board games. Cognitive assessments were recorded pre- and post- intervention. The Physical Activity Enjoyment Survey was collected post-intervention. Statistics: The cognitive measures and Physical Activity Self-efficacy scale were analyzed using the delta scores (pre-post) in a Linear mixed models analyais. The main effect of sequence (A, B, C) and intervention (RT, ACT, NT), and visit were assessed. Significance level was set with α=0.05. If any differences were detected, the Bonferroni post-hoc test was used to determine differences. Physical Activity Enjoyment Scale post scores were compared using a General Linear Model. Alpha was set at 0.05 with a Bonferroni post-hoc test to determine differences. A secondary analysis was conducted investigating the effect of participants that completed testing individually compared to those that completed the testing in a group setting. Results: There were no significant difference in the delta score of any of the measures. The secondary analysis also found no significant difference but showed a trend that those tested individually had opposite results than those tested in a group.

ContributorsArnold, Nathaniel (Author) / Ringenbach, Shannon (Thesis advisor) / Lee, Chong (Committee member) / Der Ananian, Cheryl (Committee member) / Holzapfel, Simon (Committee member) / Bosch, Pamela (Committee member) / Arizona State University (Publisher)

Created2021

A Review of the Information Available to Pregnant Women That may Influence Their Decision to Terminate or not Terminate Fetuses With Trisomy 21

Description

Statistics show that the termination rates for fetuses with Down syndrome are substantially higher compared to the general population. Perhaps pregnant women are led to believe that this is the best option for them. The information that leads them to this conclusion could be one of the leading factors for…

Statistics show that the termination rates for fetuses with Down syndrome are substantially higher compared to the general population. Perhaps pregnant women are led to believe that this is the best option for them. The information that leads them to this conclusion could be one of the leading factors for the high termination rates. In an attempt to understand the reasons behind the high termination rates the following question must be addressed: “What information is available to pregnant women that may influence their decision to terminate or not terminate fetuses with Trisomy 21?” In order to answer this question I completed a comprehensive literature review of the information available to pregnant women in the United States after they find out there fetus has Trisomy 21. The results showed that many sources publish information that is straightforward, factual, and attempts to make sure that pregnant women are fully informed on the reality of life with a child with Down syndrome. However, there are also many sources that publish information that is biased and attempts to influence a woman’s decision of whether to keep or abort her fetus with Trisomy 21. The results from this study suggest that the message conveyed from a given article relies heavily on who is doing the writing, the type of article it is, and were it is published. This provides women with a confusing array of different ideas, as opposed to offering them objective facts and consistent information. When a pregnant woman is told that her fetus is positive for the Trisomy 21 disorder and will be born with Down syndrome, it can be a very scary and emotional time. Women in this situation deserve easy access the correct information in order to help them make an informed decision based on their own choice and not the opinion of someone else.

ContributorsFitzgerald, Grace (Author) / Maienschein, Jane (Thesis director) / Ziganshina, Dina (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / School of Molecular Sciences (Contributor)

Created2022-05

The Acute Effects of Assisted Cycling Therapy (ACT) and Resistance Training on Self-Efficacy and Exercise Perception of Adults with Down syndrome

Description

This study examines the effectiveness of two modes of exercise on self-efficacy (SE) and exercise perception (EP) in adults with Down syndrome (DS). Thirteen participants attended four sessions: a baseline assessment, an Assisted Cycling Therapy (ACT) session, a resistance training (RT) session, and a session of no training (NT). In…

This study examines the effectiveness of two modes of exercise on self-efficacy (SE) and exercise perception (EP) in adults with Down syndrome (DS). Thirteen participants attended four sessions: a baseline assessment, an Assisted Cycling Therapy (ACT) session, a resistance training (RT) session, and a session of no training (NT). In the baseline assessment, 1-repetition max (1RM) measurements and voluntary pedal rate measurements were taken. In the cycling intervention, the participant completed 30 minutes of assisted cycling at 35 percent greater than their voluntary pedaling rate. In the resistance training session, 2 sets of 8-12 repetitions of the leg press, chest press, seated row, leg curl, shoulder press, and latissimus pulldown were performed. During the session of no training, participants played board games with student researchers for 35 minutes.Two subsets of the Physical Activity and Self Efficacy Survey were administered prior to each session (i.e., pretest) and after the intervention (i.e., post-test). The results were consistent with the hypothesis that ACT would lead to higher SE than RT or NT. However, ACT did not lead to higher EP than RT or NT as hypothesized. Additionally, it was hypothesized that RT would lead to higher SE and EP than NT, but the results did not support this. In conclusion, an acute session of ACT demonstrated a significant trend for improved self-efficacy in adults with DS.

ContributorsOberbillig, Nicole (Author) / Ringenbach, Shannon (Thesis director) / Ofori, Edward (Committee member) / School of International Letters and Cultures (Contributor) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)

Created2020-05

Fitzgerald Final Project (Spring 2022)

Description

Statistics show that the termination rates for fetuses with Down syndrome are substantially higher compared to the general population. Perhaps pregnant women are led to believe that this is the best option for them. The information that leads them to this conclusion could be one of the leading factors for…

Statistics show that the termination rates for fetuses with Down syndrome are substantially higher compared to the general population. Perhaps pregnant women are led to believe that this is the best option for them. The information that leads them to this conclusion could be one of the leading factors for the high termination rates. In an attempt to understand the reasons behind the high termination rates the following question must be addressed: “What information is available to pregnant women that may influence their decision to terminate or not terminate fetuses with Trisomy 21?” In order to answer this question I completed a comprehensive literature review of the information available to pregnant women in the United States after they find out there fetus has Trisomy 21. The results showed that many sources publish information that is straightforward, factual, and attempts to make sure that pregnant women are fully informed on the reality of life with a child with Down syndrome. However, there are also many sources that publish information that is biased and attempts to influence a woman’s decision of whether to keep or abort her fetus with Trisomy 21. The results from this study suggest that the message conveyed from a given article relies heavily on who is doing the writing, the type of article it is, and were it is published. This provides women with a confusing array of different ideas, as opposed to offering them objective facts and consistent information. When a pregnant woman is told that her fetus is positive for the Trisomy 21 disorder and will be born with Down syndrome, it can be a very scary and emotional time. Women in this situation deserve easy access the correct information in order to help them make an informed decision based on their own choice and not the opinion of someone else.

ContributorsFitzgerald, Grace (Author) / Maienschein, Jane (Thesis director) / Ziganshina, Dina (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)

Created2022-05

Fitzgerald Thesis Presentation (Spring 2022)

Description

Statistics show that the termination rates for fetuses with Down syndrome are substantially higher compared to the general population. Perhaps pregnant women are led to believe that this is the best option for them. The information that leads them to this conclusion could be one of the leading factors for…

Statistics show that the termination rates for fetuses with Down syndrome are substantially higher compared to the general population. Perhaps pregnant women are led to believe that this is the best option for them. The information that leads them to this conclusion could be one of the leading factors for the high termination rates. In an attempt to understand the reasons behind the high termination rates the following question must be addressed: “What information is available to pregnant women that may influence their decision to terminate or not terminate fetuses with Trisomy 21?” In order to answer this question I completed a comprehensive literature review of the information available to pregnant women in the United States after they find out there fetus has Trisomy 21. The results showed that many sources publish information that is straightforward, factual, and attempts to make sure that pregnant women are fully informed on the reality of life with a child with Down syndrome. However, there are also many sources that publish information that is biased and attempts to influence a woman’s decision of whether to keep or abort her fetus with Trisomy 21. The results from this study suggest that the message conveyed from a given article relies heavily on who is doing the writing, the type of article it is, and were it is published. This provides women with a confusing array of different ideas, as opposed to offering them objective facts and consistent information. When a pregnant woman is told that her fetus is positive for the Trisomy 21 disorder and will be born with Down syndrome, it can be a very scary and emotional time. Women in this situation deserve easy access the correct information in order to help them make an informed decision based on their own choice and not the opinion of someone else.

ContributorsFitzgerald, Grace (Author) / Maienschein, Jane (Thesis director) / Ziganshina, Dina (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)

Created2022-05

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