Novices and experts show distinct differences in the performance of many tasks. Experts may perform a task quickly and accurately with seemingly little attention or effort, whilst novices will perform the same task more slowly and with great effort. The transition from novice to expert performance occurs only after extended practice and has been conceptualized as a transition from controlled to automatic processing, and has been modeled as a reduction in attention or cognitive resources. Alternatively, based on findings relating to learning in the domain of number arithmetic, it has also been modeled as a transition from an algorithmic, or computationally-based process, to the use of memory retrieval. However, relatively few studies have investigated the changes in brain activity associated with such a transition. In this study, the Steady-State Probe Topography technique was used to investigate differences in the topography of the Steady-State Visual Evoked Potential (SSVEP) between an unpracticed and a well-practiced analogue of number arithmetic, Alphabet arithmetic. Subjects showed decreases in response time with practice that followed a power law and were suggestive of automatization. During initial, unpracticed performance of the task, processing of the Alphabet Arithmetic equations was characterised by increased SSVEP amplitude and decreased latency in frontal regions, whilst after extended practice, performance was characterised by reduced SSVEP amplitude and increased latency. It is suggested that the frontal activity during the initial, unpracticed stage of the task implicates a role for working memory, whilst the amplitude decrease and latency increase observed in the well-practiced task may reflect a reduction in excitation, consistent with ideas of an improvement in brain efficiency, and possibly an increase in inhibitory processes.

The phenomenon of the increase in alpha EEG activity associated with eye closure has been shown to be successful for implementing environmental control for disabled persons. Studies in this thesis investigate strategies which improve the reliability, robustness, and ease of use of alpha EEG control systems. Primarily, research covers the effectiveness of alpha EEG detection algorithms (with regard to detection time and susceptibility to artifact) and the construction and use of EEG sensing electrodes. Many new techniques for the detection of the increase of alpha EEG associated with eye closure are researched, developed, implemented and evaluated. All detection techniques are compared to a conventional method using a novel performance parameterisation criterion. In conjunction with the application of the same EEG data sets to all techniques, the use of the performance criteria enables a fair and quantitative comparison to be made between alpha detection methodologies. Detection techniques employed include enhanced versions of conventional methods, localisation of apparent alpha sources in the brain, and preprocessing methods (such as spatial filtering, adaptive filtering and independent component analysis). The best performance of alpha EEG detection was given by the source power alpha localisation technique, which showed statistically significant and practically important improvements in performance over conventional techniques. Additionally, this localisation technique is convenient and fast to implement. In situations in which electrodes are intended for unsupervised use with environmental control systems, the evaluation of alternative electrode types to the conventional wet electrodes is required, as the use of wet electrodes has several drawbacks. The performance of wet, dry and insulating electrodes is compared in this research. One aspect of the quantitative comparison of electrodes types is the measurement of contact impedance. To enable the fast and accurate measurement of impedance spectra, a new impedance spectroscopy system was developed as part of this thesis. In addition to comparison of impedance criteria, electrodes were evaluated in the presence movement-based, and electric field induced, artifacts. The electrode comparisons were carried out in a direct and quantitative manner in a controlled test environment for the first time. Results indicate that, in contrast to earlier reports, both dry and insulating electrode perform well with respect to artifact and offer a viable alternative to wet electrodes for long-term monitoring of biosignals from the surface of the skin. More improvements are required before such electrodes are suitable for EEG usage.

Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2009. / A thesis submitted for the degree of Doctorate of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2009. Typescript. Bibliography: p. 153-183.

Thesis (Ph. D.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 160 pages. Includes vita. Includes bibliographical references.

published_or_final_version / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

Alpha neurofeedback training has been put forward for use in the optimal performance field as a way to enhance cognitive abilities and musical performance amongst others. The literature to date, however, has been characterised by methodological limitations and disagreement on procedural and analytic matters which makes drawing conclusions and comparing results problematic. To provide clarity to the field, and to enable effective investigation of the usefulness of alpha neurofeedback training in the realm of optimal performance, it would be useful if a standardised way of conducting alpha neurofeedback was established. It is unclear, for instance, what influence the current variations have on participants’ ability to train their alpha and to the outcome (e.g. on cognition) of their performance. This thesis therefore sets out to investigate whether there is an optimum methodology for alpha neurofeedback training. The first experiment was designed to establish an index of learning to use in the successive experiments; that is, to establish how alpha should be measured and how participants’ performance should be analysed. Fifty-two participants were given 10 sessions of once weekly alpha (8-12Hz) enhancement and alpha suppression training at Pz. From the results of this first experiment it was decided that amplitude and per cent time would be the measures used to investigate participants’ performance and that analyses of participants’ performance both within and across sessions would be examined. Further, it was decided that baseline measures needed to be incorporated in to the analyses in order to establish a clearer picture of participants’ ability to learn. Experiment 2 involved training 33 participants to both enhance and suppress their alpha (8-12Hz) at Pz. Over the course of 10 once weekly sessions, 17 participants trained with their eyes open and 16 were trained with their eyes closed. The results suggested that eyes open alpha neurofeedback training is a more optimal training paradigm than eyes closed. The third experiment therefore set out to examine whether the type of eyes open training has an influence on participants’ performance. Specifically, 15 participants were given audio feedback, 15 were given audio-visual feedback, and 17 were given visual feedback over the course of 10 once weekly alpha (8-12Hz) enhancement and alpha suppression sessions. The results showed that of the 3 types of feedback, audio feedback produced the more optimal results. Although there are further aspects of methodology and analysis to be investigated, the results from this thesis suggest that these fundamental design decisions do make a difference to the participants’ ability to exert a conscious control over their own EEG alpha activity suggesting that there is, in fact, an optimum methodology for alpha (8-12Hz) neurofeedback training.

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