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"McDonnell, Michelle N."
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The Effect of an Acute Bout of Moderate-Intensity Aerobic Exercise on Motor Learning of a Continuous Tracking Task
2016
There is evidence for beneficial effects of acute and long-term exercise interventions on several forms of memory, including procedural motor learning. In the present study we examined how performing a single bout of continuous moderate intensity aerobic exercise would impact motor skill acquisition and retention in young healthy adults, compared to a period of rest. We hypothesized that exercise would improve motor skill acquisition and retention, compared to motor practice alone.
Sixteen healthy adults completed sessions of aerobic exercise or seated rest that were immediately followed by practice of a novel motor task (practice). Exercise consisted of 30 minutes of continuous cycling at 60% peak O2 uptake. Twenty-four hours after practice, we assessed motor learning with a no-exercise retention test (retention). We also quantified changes in offline motor memory consolidation, which occurred between practice and retention (offline). Tracking error was separated into indices of temporal precision and spatial accuracy.
There were no differences between conditions in the timing of movements during practice (p = 0.066), at retention (p = 0.761), or offline (p = 0.966). However, the exercise condition enabled participants to maintain spatial accuracy during practice (p = 0.477); whereas, following rest performance diminished (p = 0.050). There were no significant differences between conditions at retention (p = 0.532) or offline (p = 0.246).
An acute bout of moderate-intensity aerobic exercise facilitated the maintenance of motor performance during skill acquisition, but did not influence motor learning. Given past work showing that pairing high intensity exercise with skilled motor practice benefits learning, it seems plausible that intensity is a key modulator of the effects of acute aerobic exercise on changes in complex motor behavior. Further work is necessary to establish a dose-response relationship between aerobic exercise and motor learning.
Journal Article
The role of GABAB receptors in intracortical inhibition in the human motor cortex
by
Orekhov, Yuri
,
McDonnell, Michelle N.
,
Ziemann, Ulf
in
Biological and medical sciences
,
Brain
,
Cortex
2006
While GABAB receptors are thought to have an important role in mediating long interval intracortical inhibition (LICI) in the human motor cortex, the effect of a selective GABAB receptor agonist on this measure has not been directly tested. Nine healthy volunteers ingested either 50 mg baclofen (BAC) or placebo (PBO) in a randomized, double blind crossover design, with the second session one week later. We used transcranial magnetic stimulation to assess motor threshold, motor evoked potential (MEP) amplitude, cortical silent period (CSP) duration, short interval intracortical inhibition (SICI) and LICI before and 90 min following drug intake. There was no specific effect of drug on motor threshold, MEP amplitude or CSP duration. BAC resulted in a significant increase in LICI (P=0.002) and a significant decrease in SICI (P=0.046) while PBO had no effect. Our findings demonstrate that the enhanced GABAB receptor activation results in differential effects on these two measures of intracortical inhibition in the human motor cortex. The increase in LICI is likely to be a result of increased GABAB receptor mediated inhibitory post-synaptic potentials, while the reduction in SICI may relate to the activation of pre-synaptic GABAB receptors reducing GABA release.
Journal Article
The Effect of Aerobic Exercise on Neuroplasticity within the Motor Cortex following Stroke
by
Murdoch, Kate
,
Buckley, Jonathan D.
,
McDonnell, Michelle N.
in
Aerobic exercises
,
Aerobics
,
Aged
2016
Aerobic exercise is associated with enhanced plasticity in the motor cortex of healthy individuals, but the effect of aerobic exercise on neuroplasticity following a stroke is unknown.
The aim of this study was to compare corticomotoneuronal excitability and neuroplasticity in the upper limb cortical representation following a single session of low intensity lower limb cycling, or a rest control condition.
We recruited chronic stroke survivors to take part in three experimental conditions in a randomised, cross-over design. Corticomotoneuronal excitability was examined using transcranial magnetic stimulation to elicit motor evoked potentials in the affected first dorsal interosseus muscle. Following baseline measures, participants either cycled on a stationary bike at a low exercise intensity for 30 minutes, or remained resting in a seated position for 30 minutes. Neuroplasticity within the motor cortex was then examined using an intermittent theta burst stimulation (iTBS) paradigm. During the third experimental condition, participants cycled for the 30 minutes but did not receive any iTBS.
Twelve participants completed the study. We found no significant effect of aerobic exercise on corticomotoneuronal excitability when compared to the no exercise condition (P > 0.05 for all group and time comparisons). The use of iTBS did not induce a neuroplastic-like response in the motor cortex with or without the addition of aerobic exercise.
Our results suggest that following a stroke, the brain may be less responsive to non-invasive brain stimulation paradigms that aim to induce short-term reorganisation, and aerobic exercise was unable to induce or improve this response.
Journal Article
Anodal transcranial direct current stimulation to the cerebellum improves handwriting and cyclic drawing kinematics in focal hand dystonia
by
Ridding, Michael C.
,
Bradnam, Lynley V.
,
McDonnell, Michelle N.
in
Botulinum toxin
,
Brain research
,
Cerebellar-brain inhibition
2015
There is increasing evidence that the cerebellum has a role in the pathophysiology of primary focal hand dystonia and might provide an intervention target for non-invasive brain stimulation to improve function of the affected hand. The primary objective of this study was to determine if cerebellar transcranial direct current stimulation (tDCS) improves handwriting and cyclic drawing kinematics in people with hand dystonia, by reducing cerebellar-brain inhibition (CBI) evoked by transcranial magnetic stimulation (TMS). Eight people with dystonia (5 writer's dystonia, 3 musician's dystonia) and eight age-matched controls completed the study and underwent cerebellar anodal, cathodal and sham tDCS in separate sessions. Dystonia severity was assessed using the Writer's Cramp Rating Scale (WRCS) and the Arm Dystonia Disability Scale (ADDS). The kinematic measures that differentiated the groups were; mean stroke frequency during handwriting and fast cyclic drawing and average pen pressure during light cyclic drawing. TMS measures of cortical excitability were no different between people with FHD and controls. There was a moderate, negative relationship between TMS-evoked CBI at baseline and the WRCS in dystonia. Anodal cerebellar tDCS reduced handwriting mean stroke frequency and average pen pressure, and increased speed and reduced pen pressure during fast cyclic drawing. Kinematic measures were not associated with a decrease in CBI within an individual. In conclusion, cerebellar anodal tDCS appeared to improve kinematics of handwriting and circle drawing tasks; but the underlying neurophysiological mechanism remains uncertain. A study in a larger homogeneous population is needed to further investigate the possible therapeutic benefit of cerebellar tDCS in dystonia.
Journal Article
The role of GABA(B) receptors in intracortical inhibition in the human motor cortex
by
McDonnell, Michelle N
,
Orekhov, Yuri
,
Ziemann, Ulf
in
Adult
,
Analysis of Variance
,
Baclofen - pharmacology
2006
While GABA(B) receptors are thought to have an important role in mediating long interval intracortical inhibition (LICI) in the human motor cortex, the effect of a selective GABA(B) receptor agonist on this measure has not been directly tested. Nine healthy volunteers ingested either 50 mg baclofen (BAC) or placebo (PBO) in a randomized, double blind crossover design, with the second session one week later. We used transcranial magnetic stimulation to assess motor threshold, motor evoked potential (MEP) amplitude, cortical silent period (CSP) duration, short interval intracortical inhibition (SICI) and LICI before and 90 min following drug intake. There was no specific effect of drug on motor threshold, MEP amplitude or CSP duration. BAC resulted in a significant increase in LICI (P=0.002) and a significant decrease in SICI (P=0.046) while PBO had no effect. Our findings demonstrate that the enhanced GABA(B) receptor activation results in differential effects on these two measures of intracortical inhibition in the human motor cortex. The increase in LICI is likely to be a result of increased GABA(B) receptor mediated inhibitory post-synaptic potentials, while the reduction in SICI may relate to the activation of pre-synaptic GABA(B) receptors reducing GABA release.
Journal Article
Transcranial Doppler ultrasound to assess cerebrovascular reactivity: reliability, reproducibility and effect of posture
by
Howe, Peter R.C.
,
McDonnell, Michelle N.
,
Cutting, Mark A.
in
Anatomy and Physiology
,
Blood flow
,
Brain research
2013
Transcranial Doppler ultrasound (TCD) allows measurement of blood flow velocities in the intracranial vessels, and can be used to assess cerebral vasodilator responses to a hypercapnic stimulus. The reliability of this technique has not been established, nor is there agreement about whether the technique should be performed in sitting or lying postures. We tested the intra- and inter-rater reliability of measures of cerebrovascular reactivity (CVR) in 10 healthy adults, in sitting and lying postures. Participants underwent triplicate bilateral ultrasound assessment of flow velocities in the middle cerebral arteries whilst sitting and lying supine prior to and during inhalation of Carbogen (5% CO2, 95% O2) for 2 min. This procedure was performed twice by each of two raters for a total of four sessions. CVR was calculated as the difference between baseline and the peak blood flow velocity attained during CO2 inhalation. Intraclass correlation coefficients (ICCs) for intra-rater reliability were greater sitting than lying for both raters (e.g. Rater 1 ICC sitting = 0.822, lying = 0.734), and inter-rater reliability was also greater in sitting (e.g. sitting ICC = 0.504, lying = 0.081). These results suggest that assessment of CVR using TCD should be performed with participants sitting in order to maximise CVR measurement reliability.
Journal Article
A qualitative evaluation of scalpel skill teaching of podiatry students
2017
Background
Degrees in health disciplines need a balance of theoretical knowledge and sufficient clinical practice to meet registration requirements, in particular those requiring specialist skills such as the use of scalpels and other small instruments, such as podiatry. However, despite this requirement there is a scarcity of literature and research to inform teaching of these particular manual clinical skills. Therefore, the aims of this study were to determine the current approaches being used to teach manual skills, in particular scalpel skills, in university podiatry programs in Australia and New Zealand, and to explore what issues, challenges and innovations exist.
Methods
A qualitative study, consisting of semi-structured interviews with staff at eight university podiatry programs in Australia and New Zealand was undertaken to determine how these skills are taught and evaluated, and how poor performers are managed. A conventional content analysis technique was used to analyse and code interview data, with the resultant categories reported.
Results
Approaches to teaching manual clinical skills, in particular scalpel skills, appear to be consistent between university programs in Australia and New Zealand in utilising didactic-style content, demonstration, physical practice on inanimate objects and real skin, and often the use of supplementary audio-visual material. The main reported differences between programs were in methods and processes of practice, with controversy regarding the use of inanimate objects versus real skin for practice.
Conclusions
Despite a lack of research and literature surrounding this topic, the approach to teaching is relatively consistent between programs with greatest disparity being the structure and duration of practice. Key issues for teaching staff in teaching manual skills were students’ clinical exposure, motivation, levels of anxiety and dexterity.
Journal Article
Association of Accelerometer-Measured Sedentary Time and Physical Activity With Risk of Stroke Among US Adults
2022
The amount and intensity of physical activity required to prevent stroke are yet to be fully determined because of previous reliance on self-reporting measures. Furthermore, the association between objectively measured time spent being sedentary as an independent risk factor for stroke is unknown.
To investigate the associations of accelerometer-measured sedentary time and physical activity of varying intensity and duration with the risk of incident stroke.
This cohort study involved participants who were enrolled in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study from February 5, 2003, to October 30, 2007. Accelerometer data were collected from 7607 Black and White adults 45 years or older in the contiguous US between May 12, 2009, and January 5, 2013. Data on other races and ethnicities were not collected for scientific and clinical reasons. By design, Black adults and residents of the southeastern US stroke belt and stroke buckle were oversampled. Data were analyzed from May 5, 2020, to November 11, 2021.
Sedentary time, light-intensity physical activity (LIPA), and moderate- to vigorous-intensity physical activity (MVPA) were measured using a hip-mounted accelerometer worn for 7 consecutive days and stratified by tertile for the analyses.
Incident stroke.
Among 7607 participants, the mean (SD) age was 63.4 (8.5) years; 4145 participants (54.5%) were female, 2407 (31.6%) were Black, and 5200 (68.4%) were White. A total of 2523 participants (33.2%) resided in the stroke belt, and 1638 (21.5%) resided in the stroke buckle. Over a mean (SD) of 7.4 (2.5) years of follow-up, 286 incident stroke cases (244 ischemic [85.3%]) occurred. The fully adjusted hazard ratios (HRs) for incident stroke in the highest tertile compared with the lowest tertile were 0.74 (95% CI, 0.53-1.04; P = .08) for LIPA and 0.57 (95% CI, 0.38-0.84; P = .004) for MVPA. Higher sedentary time was associated with a 44% greater risk of incident stroke (HR, 1.44; 95% CI, 0.99-2.07; P = .04). When comparing the highest with the lowest tertile, mean sedentary bout duration was associated with a significantly greater risk of incident stroke (HR, 1.53; 95% CI, 1.10-2.12; P = .008). After adjustment for sedentary time, the highest tertile of unbouted MVPA (shorter bouts [1-9 minutes]) was associated with a significantly lower risk of incident stroke compared with the lowest tertile (HR, 0.62; 95% CI, 0.41-0.94; P = .02); however, bouted MVPA (longer bouts [at least 10 minutes]) was not (HR, 0.78; 95% CI, 0.53-1.15; P = .17). When expressed as continuous variables, sedentary time was positively associated with incident stroke risk (HR per 1-hour/day increase in sedentary time: 1.14; 95% CI, 1.02-1.28; P = .02), and LIPA was negatively associated with incident stroke risk (HR per 1-hour/day increase in LIPA: 0.86; 95% CI, 0.77-0.97; P = .02).
In this cohort study, objectively measured LIPA, MVPA, and sedentary time were significantly and independently associated with incident stroke risk. Longer sedentary bout duration was also independently associated with an increased risk of incident stroke. These findings suggest that replacing sedentary time with LIPA, or even very short bouts of MVPA, may lower stroke risk, supporting the concept of moving more and sitting less as a beneficial stroke risk reduction strategy among adults.
Journal Article
Regular group exercise is associated with improved mood but not quality of life following stroke
by
McDonnell, Michelle N.
,
Hillier, Susan L.
,
Bryan, Janet
in
Activities of daily living
,
Anxiety
,
Caregivers
2014
Purpose. People with stroke living in the community have an increased prevalence of depression and lower quality of life than healthy older adults. This cross-sectional observational study investigated whether participation in regular exercise was associated with improved mood and quality of life. Methods. We recruited three groups of community dwelling participants: 13 healthy older adults, 17 adults post-stroke who regularly participated in group exercise at a community fitness facility and 10 adults post-stroke who did not regularly exercise. We measured mood using the Depression, Anxiety, Stress Scale (DASS) and quality of life using the Assessment of Quality of Life (AQoL) scale. Results. Levels of stress and depression were significantly greater in the people with stroke who did not undertake regular exercise (p = 0.004 and p = 0.004 respectively), although this group had more recent strokes (p < 0.001). Both stroke groups had lower quality of life scores (p = 0.04) than the healthy adults. Conclusions. This small, community-based study confirms that people following stroke report poorer quality of life than stroke-free individuals. However, those who exercise regularly have significantly lower stress and depression compared to stroke survivors who do not. Future research should focus on the precise type and amount of exercise capable of improving mood following stroke.
Journal Article
Physical activity habits and preferences in the month prior to a first-ever stroke
by
McDonnell, Michelle N.
,
Esterman, Adrian J.
,
Walker, Jenny
in
Activities of daily living
,
Chronic diseases
,
Chronic illnesses
2014
Background. Physical inactivity is a powerful risk factor for stroke and other chronic diseases. The aim of this study was to explore physical activity habits and preferences in the month leading up to a first-ever stroke, and to determine whether participants were aware of the link between stroke and physical activity. Methods. We undertook an observational study with 81 participants recently admitted to a stroke unit. Participants reported their pre-morbid physical activity preferences and habits and completed the Barriers to Physical Activity and Disability Survey. Data were analysed with summative content analysis and descriptive statistics. Results. Only 31% of participants were aware that physical inactivity was associated with stroke. Most participants defined physical activity with examples of instrumental activities of daily living (IADL) and walking (48% of responses), and IADLs constituted their most frequent regular physical activity (38% of responses). The barriers to physical activity reported by participants most frequently were lack of motivation (52%), lack of interest (50%) and lack of energy (42%). Conclusions. Regular physical activity is important to prevent stroke and other chronic diseases but adults at risk of stroke have little awareness of the risks of physical inactivity and little motivation to undertake regular exercise.
Journal Article