Simon Vogrin

Publications (35) View all

• Source

  Available from: Mark James Cook

  Dataset: j.1552-6569.2012.00744.x

  Xingwen Liang, Levin Kuhlmann, Leigh A Johnston, David B Grayden, Simon Vogrin, Rosemary Crossley, Karen Fuller, Mark Lourensz, Mark J Cook
• Source

  Available from: Mark James Cook

  Article: Extending Communication for Patients with Disorders of Consciousness.

  Xingwen Liang, Levin Kuhlmann, Leigh A Johnston, David B Grayden, Simon Vogrin, Rosemary Crossley, Karen Fuller, Mark Lourensz, Mark J Cook
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  ABSTRACT: BACKGROUND AND PURPOSE: The difficulty of distinguishing disorders of consciousness from certain disorders of communication leads to the possibility of false diagnosis. Our aim is to communicate with patients with disorders of consciousness through asking them to answer questions with "yes/no" by performing mental imagery tasks using functional magnetic resonance imaging (fMRI). METHODS: A 1.5 T fMRI study with 5 patients and a control group is presented. Speech comprehension, mental imagery, and question-answer tests were performed. RESULTS: The imagery task of mental calculation produced equally distinct activation patterns when compared to navigation and motor imagery in controls. For controls, we could infer answers to questions based on imagery activations. Two patients produced activations in similar areas to controls for certain imagery tasks, however, no activations were observed for the question-answer task. CONCLUSIONS: The results from 2 patients provide independent support of similar work by others with 3 T fMRI, and demonstrate broader clinical utility for these tests at 1.5 T despite lower signal-to-noise ratio. Based on the control results, mental calculation adds a robust imagery task for use in future studies of this kind. J Neuroimaging 2012;XX:1-8.
  Journal of neuroimaging: official journal of the American Society of Neuroimaging 08/2012; · 1.72 Impact Factor
• Source

  Available from: Mark James Cook

  Article: Probing for cortical excitability.

  Dean R Freestone, Anthony N Burkitt, Alan Lai, Timothy S Nelson, David B Grayden, Simon Vogrin, Michael Murphy, Wendyl D'Souza, Radwa Badawy, Levin Kuhlmann, Mark J Cook
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  ABSTRACT: This paper introduces a new method for measuring cortical excitability using an electrical probing stimulus via intracranial electroencephalography (iEEG). Stimuli consisted of 100 single bi-phasic pulses, delivered every 10 minutes. Neural excitability is estimated by extracting a feature from the iEEG responses to the stimuli, which we dub the mean phase variance (PV). We show that the mean PV increases with the rate of inter-ictal discharges in one patient. In another patient, we show that the mean PV changes with sleep and an epileptic seizure. The results demonstrate a proof-of-principal for the method to be applied in a seizure anticipation framework.
  Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:1644-7.
• Article: Clinical utility of distributed source modelling of interictal scalp EEG in focal epilepsy.

  C Plummer, M Wagner, M Fuchs, S Vogrin, L Litewka, S Farish, C Bailey, A S Harvey, M J Cook
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  ABSTRACT: Assess the clinical utility of non-invasive distributed EEG source modelling in focal epilepsy. Interictal epileptiform discharges were recorded from eight patients - benign focal epilepsy of childhood (BFEC), four; mesial temporal lobe epilepsy (MTLE), four. EEG source localization (ESL) applied 48 forward-inverse-subspace set-ups: forward - standardized, leadfield-interpolated boundary element methods (BEMs, BEMi), finite element method (FEMi); inverse - minimum norm (MNLS), L1 norm (L1), low resolution electromagnetic tomography (LORETA), standardized LORETA (sLORETA); subspace- whole volume (3D), cortex with rotating sources (CxR), cortex with fixed sources (CxN), cortex with fixed extended sources (patch). Current density reconstruction (CDR) maxima defined 'best-fit'. From 19,200 CDR parameter results and 2304 CDR maps, the dominant variables on best-fit were inverse model and subspace constraint. The most clinically meaningful and statistically robust results came with sLORETA-CxR/patch (lower Rolandic in BFEC, basal temporal lobe in MTLE). Computation time was inverse model dependent: sub-second (MNLS, sLORETA), seconds (L1), minutes (LORETA). From the largest number of distributed ESL approaches compared in a clinical setting, an optimum modelling set-up for BFEC and MTLE incorporated sLORETA (inverse), CxR or patch (subspace), and either BEM or FEMi (forward). Computation is efficient and CDR results are reproducible. Distributed source modelling demonstrates clinical utility for the routine work-up of unilateral BFEC of the typical Rolandic variety, and unilateral MTLE secondary to hippocampal sclerosis.
  Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 05/2010; 121(10):1726-39. · 3.12 Impact Factor
• Article: Volumetric analysis of a specific language region - the planum temporale.

  L Vadlamudi, R Hatton, K Byth, J Harasty, S Vogrin, M J Cook, A F Bleasel
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  ABSTRACT: Planum temporale volumes were determined for 42 control children (ages 4.2-15.7 years) using magnetic resonance imaging. The mean left planum temporale volume was 2729 mm3 (SD = 567) and the mean right planum temporale volume was 2758 mm3 (SD = 546). No significant hemispheric asymmetry was demonstrated. Analysis of co-variance (ANCOVA) showed that the absolute and proportional planum temporale volumes were not significantly associated with age or gender. We also demonstrated a reproducible method for planum temporale volume measurement by acquiring images in the coronal plane and then visualising the sagittal plane to improve accuracy for the posterior border.
  Journal of Clinical Neuroscience 03/2006; 13(2):206-13. · 1.25 Impact Factor