ORCID Profile
0000-0002-4025-4019
Current Organisation
Flinders University
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Publisher: IGI Global
Date: 2012
DOI: 10.4018/978-1-60960-821-7.CH009
Abstract: The hybrid world provides a framework for the creation of lessons that teach and test knowledge in the second language. In one of our ex le grammar and vocabulary lessons, the Thinking Head instructs the student to move a tiger to a lake—a student moving the toy tiger in the real world effectively moves a virtual tiger in the virtual arena. This type of interaction is beneficial for computer-based language learning especially because we are able to see a student has successfully understood the directions if the tiger is moved to the vicinity of the virtual lake. Physical movement helps the learner to internalise the novel relationships in the second language. We also provide for additional forms of communication, including dialogue with an embodied conversational agent and writing stories using markers on a whiteboard. In summary, our system provides a natural interface with which to communicate with the hybrid-reality learning environment.
Publisher: IEEE
Date: 05-2012
Publisher: Springer International Publishing
Date: 2016
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.CLINPH.2015.12.009
Abstract: Validate independent component analysis (ICA) for removal of EMG contamination from EEG, and demonstrate a heuristic, based on the gradient of EEG spectra (slope of graph of log EEG power vs log frequency, 7-70 Hz) from paralysed awake humans, to automatically identify and remove components that are predominantly EMG. We studied the gradient of EMG-free EEG spectra to quantitatively inform the choice of threshold. Then, pre-existing EEG from 3 disparate experimental groups was examined before and after applying the heuristic to validate that the heuristic preserved neurogenic activity (Berger effect, auditory odd ball, visual and auditory steady state responses). (1) ICA-based EMG removal diminished EMG contamination up to approximately 50 Hz, (2) residual EMG contamination using automatic selection was similar to manual selection, and (3) task-induced cortical activity remained, was enhanced, or was revealed using the ICA-based methodology. This study further validates ICA as a powerful technique for separating and removing myogenic signals from EEG. Automatic processing based on spectral gradients to exclude EMG-containing components is a conceptually simple and valid technique. This study strengthens ICA as a technique to remove EMG contamination from EEG whilst preserving neurogenic activity to 50 Hz.
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.IJPSYCHO.2014.10.006
Abstract: The serious impact of electromyogram (EMG) contamination of electroencephalogram (EEG) is well recognised. The objective of this research is to demonstrate that combining independent component analysis with the surface Laplacian can eliminate EMG contamination of the EEG, and to validate that this processing does not degrade expected neurogenic signals. The method involves sequential application of ICA, using a manual procedure to identify and discard EMG components, followed by the surface Laplacian. The extent of decontamination is quantified by comparing processed EEG with EMG-free data that was recorded during pharmacologically induced neuromuscular paralysis. The combination of the ICA procedure and the surface Laplacian, with a flexible spherical spline, results in a strong suppression of EMG contamination at all scalp sites and frequencies. Furthermore, the ICA and surface Laplacian procedure does not impair the detection of well-known, cerebral responses alpha activity with eyes-closed ERP components (N1, P2) in response to an auditory oddball task and steady state responses to photic and auditory stimulation. Finally, more flexible spherical splines increase the suppression of EMG by the surface Laplacian. We postulate this is due to ICA enabling the removal of local muscle sources of EMG contamination and the Laplacian transform being insensitive to distant (postural) muscle EMG contamination.
Publisher: IGI Global
Date: 2011
DOI: 10.4018/978-1-60960-617-6.CH002
Abstract: Autism spectrum disorder (ASD) makes communication and social interaction very difficult for those affected. Existing studies have reported positive results for teaching social skills to children with ASD using human-controlled virtual agents and language skills using autonomous agents. Here we combine these approaches and investigate the potential of autonomous agents as social skills tutors. A system for audio-visually synthesising an agent is developed towards this purpose and utilised together with two tutoring modules that we specifically designed for teaching conversation skills and how to deal with bullying. Following evaluation, children’s thoughts about their experience with the virtual tutor were investigated through use of a survey. The positive feedback and the modest but significant improvements in test scores for both modules suggest that this strategy for teaching social skills has much potential and that further research and development in this area would be eminently worthwhile.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2013
Publisher: Springer International Publishing
Date: 2020
Publisher: ACM
Date: 16-07-2008
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.CLINPH.2007.04.027
Abstract: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation.
Publisher: IOP Publishing
Date: 28-05-2015
DOI: 10.1088/0967-3334/36/7/1469
Abstract: Electroencephalography (EEG) is challenged by high cost, immobility of equipment and the use of inconvenient conductive gels. We compared EEG recordings obtained from three systems that are inexpensive, wireless, and/or dry (no gel), against recordings made with a traditional, research-grade EEG system, in order to investigate the ability of these 'non-traditional' systems to produce recordings of comparable quality to a research-grade system. The systems compared were: Emotiv EPOC (inexpensive and wireless), B-Alert (wireless), g.Sahara (dry) and g.HI (research-grade). We compared the ability of the systems to demonstrate five well-studied neural phenomena: (1) enhanced alpha activity with eyes closed versus open (2) visual steady-state response (VSSR) (3) mismatch negativity (4) P300 and (5) event-related desynchronization/synchronization. All systems measured significant alpha augmentation with eye closure, and were able to measure VSSRs (although these were smaller with g.Sahara). The B-Alert and g.Sahara were able to measure the three time-locked phenomena equivalently to the g.HI . The Emotiv EPOC did not have suitably located electrodes for two of the tasks and synchronization considerations meant that data from the time-locked tasks were not assessed. The results show that inexpensive, wireless, or dry systems may be suitable for experimental studies using EEG, depending on the research paradigm, and within the constraints imposed by their limited electrode placement and number.
Publisher: Frontiers Media SA
Date: 21-11-2014
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.EPLEPSYRES.2008.03.012
Abstract: It is currently unknown what processes take place at the interface between non-ictal and ictal activity during seizure initiation. In this study, using paralysed awake rats, we focally inhibited astrocytic metabolism with fluorocitrate (FC), causing seizures. We measured changes in electroencephalogram (EEG) (0-300 Hz), and extracellular ion-concentrations during ictal onsets defining possible relationships with impedance-determined cell swelling. In animals showing ictal activity (69%) there were spike-wave discharges, spike-wave discharges followed by spreading depression and spreading depression without any discharges. In a high proportion of spike-wave discharges (>95%), just prior to the first spike-wave discharge, there was a decrease in the volume of the extracellular space. Following the initiation of cell swelling and prior to discharges, there were increases in high-frequency (150-300 Hz) EEG activity, increases in extracellular potassium- and decreases in extracellular calcium-concentrations. We suggest that EEG and ionic changes are not causative of cell swelling. Cell swelling due to metabolic failure in astrocytes at the injected site may release excitatory amino acids. At the same time, our results suggest ion homeostasis is not maintained and increased neuronal excitability and synchronisation occur. These could be the drivers changing normal brain activity into ictal activity.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.IJPSYCHO.2016.09.020
Abstract: Meditative techniques aim for and meditators report states of mental alertness and focus, concurrent with physical and emotional calm. We aimed to determine the electroencephalographic (EEG) correlates of five states of Buddhist concentrative meditation, particularly addressing a correlation with meditative level. We studied 12 meditators and 12 pair-matched meditation-naïve participants using high-resolution scalp-recorded EEG. To maximise reduction of EMG, data were pre-processed using independent component analysis and surface Laplacian transformed data. Two non-meditative and five meditative states were used: resting baseline, mind-wandering, absorptions 1, 2, 3, 4 and 5 (corresponding to four levels of absorption and an absorption with a different object of focus, otherwise equivalent to level 4 these five meditative states produce repeatable, distinctly different experiences for experienced meditators). The experimental protocol required participants to experience the states in the order listed above, followed immediately by the reverse. We then calculated EEG power in standard frequency bands from 1 to 80Hz. We observed decreases of central scalp beta (13-25Hz), and central low gamma (25-48Hz) power in meditators during deeper absorptions. In contrast, we identified increases in frontal midline and temporo-parietal theta power in meditators, again, during deeper absorptions. Alpha activity was increased over all meditative states, not depth-related. This study demonstrates that the subjective experiences of deepening meditation partially correspond to measures of EEG. Our results are in accord with prior studies on non-graded meditative states. These results are also consistent with increased theta correlating with tightness of focus, and reduced beta/gamma with the desynchronization associated with enhanced alertness.
Publisher: IEEE
Date: 2005
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.JNEUMETH.2017.06.011
Abstract: Cranial and cervical muscle activity (electromyogram, EMG) contaminates the surface electroencephalogram (EEG) from frequencies below 20 through to frequencies above 100Hz. It is not possible to have a reliable measure of cognitive tasks expressed in EEG at gamma-band frequencies until the muscle contamination is removed. In the present work, we introduce a new approach of using a minimum-norm based beamforming technique (sLORETA) to reduce tonic muscle contamination at sensor level. Using a generic volume conduction model of the head, which includes three layers (brain, skull, and scalp), and sLORETA, we estimated time-series of sources distributed within the brain and scalp. The sources within the scalp were considered to be muscle and discarded in forward modelling. (1) The method reduced EMG contamination, more strongly at peripheral channels (2) task-induced cortical activity was retained or revealed after removing putative muscle activity. This approach can decrease tonic muscle contamination in scalp measurements without relying on time-consuming processing of expensive MRI data. In addition, it is competitive to ICA in muscle reduction and can be reliably applied on any length of recorded data that captures the dynamics of the signals of interest. This study suggests that sLORETA can be used as a method to quantitate cranial muscle activity and reduce its contamination at sensor level.
Publisher: IEEE
Date: 07-2010
Publisher: Springer Science and Business Media LLC
Date: 20-02-2009
DOI: 10.1007/S10548-009-0081-X
Abstract: We recorded scalp electrical activity before and after full neuro-muscular paralysis in 5 volunteers and determined differences due to elimination of muscular activity on several standard applications of EEG. Due to paralysis, there were reductions in 'noisiness' of the standard scalp recordings which were maximal over the peripheral scalp, not explained by abolition of movement artefact, and best accounted for by sustained EMG activity in resting in iduals. There was a corresponding reduction in spectral power in the gamma range. In central leads, the extent of gamma frequency coherence during a non-time-locked mental task (1 s epochs) was reduced by paralysis, likely due to a reduction in gamma-frequency coherence in widely arising EMG signals. In a time-locked mental task (auditory oddball), evoked responses were qualitatively unaffected by paralysis but 3 of 4 induced gamma responses were obscured by EMG.
Publisher: Research-publishing.net
Date: 14-12-2020
DOI: 10.14705/RPNET.2020.48.1195
Abstract: This research study tends to evaluate the efficaciousness and usability of a Vocabulary Learning And Strategy Teaching Web-App (VLASTWA) – a customised and targeted web-app for (1) teaching the KeyWord Method (KWM) which is a widely investigated vocabulary learning strategy, and (2) facilitating new vocabulary learning via KWM. In this experimental study, with a between/within design, native Persian participants (n=160, age:18-60) learnt to use KWM, applied it in acquiring 22 new words, and tested this newly learnt vocabulary immediate (T1)/delayed (T2) recall. The effectiveness of the use of KWM taught within the web-app and the traditional Pen and Paper (P& P) in the experimental groups were compared with the control app and P& P groups via immediate/delayed recall of learnt vocabulary. The results suggest VLASTWA was efficient for learning new vocabulary while highlighting how meaningful and interactive it can be in accompanying and enriching Foreign Language (FL) vocabulary learning.
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2209412
Publisher: IEEE
Date: 07-2010
Publisher: Frontiers Media SA
Date: 2011
Publisher: InTech
Date: 15-09-2011
DOI: 10.5772/18688
Publisher: Springer Berlin Heidelberg
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 08-09-2017
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CLINPH.2008.01.024
Abstract: Fast electrical rhythms in the gamma range (30-100Hz) in scalp (but not intracranial) recordings are predominantly due to electromyographic (EMG) activity. We hypothesized that increased EMG activity would be augmented by mental tasks in proportion to task difficulty and the requirement of these tasks for motor or visuo-motor output. EEG was recorded in 98 subjects whilst performing cognitive tasks and analysed to generate power spectra. In four other subjects, neuromuscular blockade was achieved pharmacologically providing EMG-free spectra of EEG at rest and during mental tasks. In comparison to the paralysed condition, power of scalp electrical recordings in the gamma range varied in distribution, being maximal adjacent to cranial or cervical musculature. There were non-significant changes in mean gamma range activity due to mental tasks in paralysed subjects. In normal subjects, increases in scalp electrical activity were observed during tasks, without relationship to task difficulty, but with tasks involving limb- or eye-movement having higher power. Electrical rhythms in the gamma frequency range recorded from the scalp are inducible by mental activity and are largely due to EMG un-related to cognitive effort. EMG varies with requirements for somatic or ocular movement more than task difficulty. Severe restrictions exist on utilizing scalp recordings for high frequency EEG.
Publisher: Elsevier BV
Date: 02-2017
Publisher: Springer Berlin Heidelberg
Date: 2011
Publisher: IEEE
Date: 04-2013
Publisher: Springer Science and Business Media LLC
Date: 10-06-2016
No related grants have been discovered for Trent Lewis.