Mark Schier

Steady-State Visually Evoked Potential topography associated with a visual vigilance task

SummaryThis paper describes data which demonstrate a correlation between the magnitude of the Steady-State Visually Evoked Potential (SSVEP) and visual vigilance. The SSVEP was recorded from 64 scalp sites and elicited by a 13Hz uniform visual flicker presented continuously while subjects undertook a visual vigilance task. Fifteen right-handed males were required to view three times a series of 180 geometrical shapes comprising a sequence of 60 squares, 60 circles and a further 60 squares. Each viewing of the 180 shapes constituted a trial. Trials 1 and 2 were identical while trial 3 differed from the first two in that one of the circles was modified. Subjects were ignorant as to the location of the modified circle and prior to the third trial, were challenged to identify the modified circle. A comparison of trials 2 and 3 indicated that the appearance of the modified circle was associated with an attenuation of the SSVEP in the occipito/parietal region. The same comparison indicated a pronounced SSVEP attenuation in the centro/parietal region during the interval that subjects were anticipating the appearance of the modified circle. These results suggest a distinction between the cortical activation patterns occurring during different phases of a visual vigilance task.

A roadmap for forming successful interdisciplinary education research collaborations: a reflective approach

Current literature about interdisciplinary education research is focused on three points: conceptual definitions of interdisciplinarity, the need for interdisciplinary research to tackle the advent of problem-based research and the positive curriculum outcomes to be gained from interdisciplinary research. While this research is important, it does not always include an account of the often complex and politicised interactions that might affect the outcomes of interdisciplinary research groups. This paper provides one possible ‘roadmap’ for successful interdisciplinary collaboration. It is based on a reflective case study of the authors’ own formation of an interdisciplinary research group and the practical resolutions to both the theoretical and the practical issues involved in achieving interdisciplinarity in education research.

Evaluation of wavelet techniques in rapid extraction of ABR variations from underlying EEG

The aim of this study is to analyse an effective wavelet method for denoising and tracking temporal variations of the auditory brainstem response (ABR). The rapid and accurate extraction of ABRs in clinical practice has numerous benefits, including reductions in clinical test times and potential long-term patient monitoring applications. One method of achieving rapid extraction is through the application of wavelet filtering which, according to earlier research, has shown potential in denoising signals with low signal-to-noise ratios. The research documented in this paper evaluates the application of three such wavelet approaches on a common set of ABR data collected from eight participants. We introduced the use of the latency-intensity curve of ABR wave V for performance evaluation of tracking temporal variations. The application of these methods to the ABR required establishing threshold functions and time windows as an integral part of the research. Results revealed that the cyclic-shift-tree-denoising performed superior compared to other tested approaches. This required an ensemble of only 32 epochs to extract a fully featured ABR compared to the 1024 epochs with conventional ABR extraction based on linear moving time averaging.

A Feasibility Study of Commercially Available Audio Transducers in ABR Studies

Among numerous sources of electrical interference, stimulus artifact produced by the audio transducer (typically headphones or earphones) affects the features of an auditory Brainstem Response (ABR). At high stimulus intensities, artifacts may create a serious problem because they extend into the time frame of the ABR. The stimulus artifact depends upon the type of transducer and the electrode arrangements used. At present, expensive and complex methods are being employed to eliminate this problem.

Comparison of spontaneous and event related measures in the electroencephalogram

Some common descriptors of spontaneous EEG include the common spectral measures (including alpha and beta bands) and the less common measures of statistical moment analysis (such as activity, mobility and complexity). Of these measures, the complexity quantifies the apparent “excessive detail” of the EEG trace. Typically, around 20 seconds of EEG are required to compute these measures.