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Contributing to a meta-analysis on the effects of acute physical exercise on the executive functions of preadolescent children, adolescents and adults

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The purpose of this study, originally, was to contribute to the completion of a meta-analysis conducted by Mara Wierstra from the University of Virginia. Wierstra had requested individual participant data from two separate studies conducted in our lab: "Acute bouts

The purpose of this study, originally, was to contribute to the completion of a meta-analysis conducted by Mara Wierstra from the University of Virginia. Wierstra had requested individual participant data from two separate studies conducted in our lab: "Acute bouts of assisted cycling improves cognitive and upper extremity movement functions in adolescents with Down syndrome" and "Assisted Cycling Therapy (ACT) improves inhibition in adolescents with autism spectrum disorder." From the data requested, the participants were required to complete three separate tests (i.e., Tower of London, Trail Making Task and the Stroop Test). After compiling the data and sending it to her, we decided to conduct a small meta-analysis of our own, drawing connecting conclusions from the data from the two studies. We concluded that observationally our data suggest an advantage for ACT over voluntary cycling and no cycling across two separate populations (i.e., Autism Spectrum Disorder and Down syndrome), and across different measures of executive function (i.e., Stroop Test, Trail Making Test, and Tower of London). The data suggest that the ACT interventions may promote the upregulation of neurotropic factors leading to neurogenesis in the prefrontal cortex of the brain.

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2016-12

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Examination of One Month Retention of Executive Function in Assisted Cycling Therapy on Adolescents with Down Syndrome

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This study examines the one month retention of executive function benefits gained by adolescents with Down syndrome after an 8-week aerobic exercise intervention. Sixteen participants were randomly divided between voluntary (VC) (i.e., self-selected cadence) and assisted (AC) (i.e., 30% faster

This study examines the one month retention of executive function benefits gained by adolescents with Down syndrome after an 8-week aerobic exercise intervention. Sixteen participants were randomly divided between voluntary (VC) (i.e., self-selected cadence) and assisted (AC) (i.e., 30% faster than self-selected cadence accomplished by a motor) cycling groups, with one participant used as a control (NC). Both cycling groups rode a stationary bicycle, for 30 minutes, three times a week, for eight weeks. At the beginning (i.e., pretest) and end (posttest) of the 8-week session, three executive functions including: set-switching, inhibition, and cognitive planning, were tested. Approximately one month after the posttest, all participants underwent the cognitive testing again. The results showed that for the AC group cognitive planning improved after eight weeks of assisted cycling and these improvements were maintained after one month of no cycling. However, no significant differences were found between the cycling groups for our measure of inhibition. Set-switching appeared to be improved by both types of exercise, rather than only assisted, but the improvements were not maintained during the one month retention period for either group. Thus, our results suggest that Assisted Cycling causes potentially permanent changes in the brain in regards to cognitive planning.

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2014-05

Cellular Evaluation of Postnatal Frontal Cortex in Down Syndrome

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Down syndrome (DS) is a common genetic developmental disorder characterized by the trisomy of chromosome 21 (Hsa21). All individuals with DS have some kind of intellectual disability, associated with dysfunction in cognition-related structures, including the frontal cortex. Studies have examined

Down syndrome (DS) is a common genetic developmental disorder characterized by the trisomy of chromosome 21 (Hsa21). All individuals with DS have some kind of intellectual disability, associated with dysfunction in cognition-related structures, including the frontal cortex. Studies have examined developmental changes in the frontal cortex during prenatal stages in DS, however little is known about cortical lamination and neuronal differentiation in postnatal periods in this neurodevelopmental disorder. Therefore, we examined the quantitative and qualitative distribution of neuronal profiles containing the neuronal migration protein doublecortin (DCX), the non-phosphorylated high-molecular-weight neurofilament SMI-32, the calcium-binding proteins calbindin D-28K (Calb), calretinin (Calr), and parvalbumin (Parv), as well as human β-amyloid and APP (6E10), Aβ1-42, and phospho-tau (CP-13) in the supragranular (SG, II/III) and infragranular (IG, V/VI) layers in the DS postnatal frontal cortex compared to neurotypically developing (NTD) controls from ages 28 weeks to 196.4 weeks using immunohistochemistry. Furthermore, cortical lamination was evaluated using thionin, a Nissl stain. We found DCX-immunoreactive (-ir) cells in both the SG and IG layers in younger cases, but not in the oldest cases in both groups. Strong expression of SMI-32 immunoreactivity was observed in pyramidal cells in layers III and V in the oldest cases in both groups, however SMI-32-ir cells appeared much earlier in NTD compared to DS. We found small and fusiform Calb-ir cells in the younger cases (28 to 44 weeks), while in the oldest cases, Calb immunoreactivity was also found in pyramidal cells. Calr-ir cells appeared earlier in DS at 32 weeks compared to NTD at 44 weeks, however both groups showed large bipolar fusiform-shaped Calr-ir cells in the oldest cases. Diffuse APP/Aβ-ir plaque-like accumulations were found in the frontal cortex grey and white matter at all ages, but no Aβ1-42 immunoreactivity was detected in any case. Furthermore, neuropil (but not cellular) granular CP-13 immunostaining was seen in layer I only at 41 weeks NTD and 33 weeks DS. Cell counts show a significantly higher cell number in SG compared to IG for all the neuronal markers in both groups, except in Calb and SMI-32. In NTD, age and brain weight showed the strongest correlations with all cellular counts, except in thionin where DS had a stronger negative correlation with age and brain weight compared to NTD. In addition, height and body weight showed a strong negative correlation in NTD with the migration and neurogenesis marker DCX. These findings suggest that trisomy 21 affects the postnatal frontal cortex lamination, neuronal migration<br/>eurogenesis, and differentiation of projection pyramidal cells and interneurons, which contribute to the disruption of the local and projection inhibitory and excitatory circuitries that may underlie the cognitive disabilities in DS.

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2021-05