ORCID Profile
0000-0003-2435-077X
Current Organisation
Deakin University
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Publisher: Oxford University Press (OUP)
Date: 28-05-2019
DOI: 10.1093/BRAIN/AWZ112
Publisher: Springer Science and Business Media LLC
Date: 03-11-2020
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.JSAMS.2014.07.010
Abstract: This multimodal study investigated the motor, neurocognitive and neurophysiological responses following a sports related concussion injury in the acute-phase (up to 10 days) in sub-elite Australian football players. Between-group, repeated measures. Over the course of one season (six months), 43 male players from one football club (25.1 ± 4.5 years) were assessed for fine motor dexterity, visuomotor reaction time, implicit learning and attention. Motor cortex excitability and inhibition were assessed using transcranial magnetic stimulation. Of the 43 players, eight suffered concussion injuries, and were compared to 15 non-concussed players (active control) who returned for follow up testing. Post-concussion assessments using the aforementioned tests were carried out at 48 and 96 h, and 10 days. Compared to the non-concussed players, those who suffered concussion showed slowed fine dexterity (P = 0.02), response (P = 0.02) and movement times (P = 0.01) 48 h post-concussion. Similarly, attentional performance was reduced in the concussed group at all time points (48 h: P < 0.01 96 h: P < 0.01 and 10 days: P = 0.02) post-concussion. TMS revealed significantly increased corticospinal inhibition at 48 (P = 0.04) and 96 h post concussion (P = 0.02) with significant correlations between increased corticospinal inhibition and response (r = 0.48 P < 0.01), movement time (r = 0.42 P = 0.02), and attention performance (r = 0.44 P = 0.01). This study has demonstrated that acutely concussed Australian football players show abnormalities in motor, cognitive and neurophysiological measures with variable rates of recovery. These findings suggest that measuring the recovery of concussed athletes should incorporate a range of testing modalities rather than relying on one area of measurement in determining return to play.
Publisher: Frontiers Media SA
Date: 2013
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 11-2018
Publisher: Mary Ann Liebert Inc
Date: 07-2014
Abstract: This study investigated corticomotor excitability and inhibition, cognitive functioning, and fine motor dexterity in retired elite and amateur Australian football (AF) players who had sustained concussions during their playing careers. Forty male AF players who played at the elite level (n=20 mean age 49.7±5.7 years) or amateur level (n=20 mean age 48.4±6.9 years), and had sustained on average 3.2 concussions 21.9 years previously, were compared with 20 healthy age-matched male controls (mean age 47.56±6.85 years). All participants completed assessments of fine dexterity, visuomotor reaction time, spatial working memory (SWM), and associative learning (AL). Transcranial magnetic stimulation (TMS) was used to measure corticospinal excitability: stimulus-response (SR) curves and motor evoked potential (MEP) 125% of active motor threshold (aMT) and intracortical inhibition: cortical silent period (cSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI). Healthy participants performed better in dexterity (p=0.003), reaction (p=0.003), and movement time (p=0.037) than did both AF groups. Differences between AF groups were found in AL (p=0.027) and SWM (p=0.024). TMS measures revealed that both AF groups showed reduced cSP duration at 125% aMT (p>0.001) and differences in SR curves (p>0.001) than did healthy controls. Similarly, SICI (p=0.012) and LICI (p=0.009) were reduced in both AF groups compared with controls. Regression analyses revealed a significant contribution to differences in motor outcomes with the three measures of intracortical inhibition. The measures of inhibition differed, however, in terms of which performance measure they had a significant and unique predictive relationship with, reflecting the variety of participant concussion injuries. This study is the first to demonstrate differences in motor control and intracortical inhibition in AF players who had sustained concussions during their playing career two decades previously.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.NEUBIOREV.2014.03.017
Abstract: This systematic review and meta-analysis was conducted across studies using transcranial magnetic stimulation to investigate corticospinal excitability and inhibition in response to a dual task (DT). Quantitative analysis was performed on eleven controlled studies that had included healthy participants over the age of 18 years. Results showed a small effect size for increased corticospinal excitability for DT conditions (SMD=0.207 p=.217, and a small effect size (SMD=-0.253) demonstrating a significant decrease in corticospinal inhibition for DT conditions (p=.019). Meta-regression demonstrated that neither age, task type, or task prioritisation accounted for the high variability in effect sizes between studies. A number of possible sources of within study bias are identified, which reduced the level of evidence for study findings. The results show overall changes in corticospinal responses between ST and DT conditions however further research is necessary to investigate variables that could account for differences in corticospinal responses between studies.
Publisher: Springer Science and Business Media LLC
Date: 29-10-2016
DOI: 10.1007/S00221-015-4479-2
Abstract: Dual-tasking is intrinsic to many daily activities, including walking and driving. However, the activity of the primary motor cortex (M1) in response to dual-tasks (DT) is still not well characterised. A recent meta-analysis (Corp in Neurosci Biobehav Rev 43:74-87, 2014) demonstrated a reduction in M1 inhibition during dual-tasking, yet responses were not consistent between studies. It was suggested that DT difficulty might account for some of this between-study variability. The aim of this study was to investigate whether corticospinal excitability and M1 inhibition differed between an easier and more difficult dual-task. Transcranial magnetic stimulation (TMS) was applied to participants' abductor pollicis brevis muscle representation during a concurrent pincer grip task and stationary bike-riding. The margin of error in which to maintain pincer grip force was reduced to increase task difficulty. Compared to ST conditions, significantly increased M1 inhibition was demonstrated for the easier, but not more difficult, DT. However, there was no significant difference in M1 inhibition between easy and difficult DTs. The difference in difficulty between the two tasks may not have been wide enough to result in significant differences in M1 inhibition. Increased M1 inhibition for the easy DT condition was in opposition to the reduction in M1 inhibition found in our meta-analysis (Corp in Neurosci Biobehav Rev 43:74-87, 2014). We propose that this may be partially explained by differences in the timing of the TMS pulse between DT studies.
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