Gregory W Price

Publications (3)13.86 Total impact

• Article: The use of background EEG activity to determine stimulus timing as a means of improving rTMS efficacy in the treatment of depression: a controlled comparison with standard techniques.

  Gregory W Price, Joseph W Y Lee, Carrie-Anne L Garvey, Nathan Gibson
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  ABSTRACT: Repetitive transcranial magnetic stimulation (rTMS) treatment of depression utilizes numerous predetermined patterns of stimulation. As an alternative to using invariant stimulus timing parameters, the interactive technique delivers individual stimuli based on the background electroencephalogram (EEG) activity. This study examines the use of an EEG-dependent technique as a means to enhance the efficacy of rTMS in the treatment of depression. Forty-four patients with treatment-refractory major depression were treated, in a randomized, doubleblind, 4-week trial, with two different rTMS stimulus timing techniques (left dorsolateral prefrontal cortex). Standard rTMS utilized 10-Hz stimuli, whereas interactive rTMS applied individual stimuli in response to a selected pattern of background EEG activity analyzed in real time. Hamilton Depression Rating Scale (HDRS) and the Beck's Depression Inventory-II (BDI) scores were recorded at baseline, 2 weeks and after the final treatment. The interactive group showed a trend toward greater efficacy than the standard group in both absolute (t=-1.68; P=.100) and percentage (t=-1.74; P=.090) change in scores on HDRS (and similarly BDI). The response rate (>50% reduction) for the interactive technique of 43% (9/21) was also different to that of the standard technique (22%; 5/23; odds ratio: 2.70). The use of EEG-based TMS stimuli has been shown to be feasible in an rTMS clinical trial in treatment-resistant depression. The EEG-based interactive technique was associated with an indication of a trend toward a greater clinical effect than the standard rTMS technique. The interactive technique thus has the potential to refine the rTMS methodology and to enhance efficacy in the treatment of depression.
  Brain Stimulation 07/2010; 3(3):140-52. · 3.76 Impact Factor
• Article: A multivariate electrophysiological endophenotype, from a unitary cohort, shows greater research utility than any single feature in the Western Australian family study of schizophrenia.

  Gregory W Price, Patricia T Michie, Julie Johnston, Hamish Innes-Brown, Aaron Kent, Peter Clissa, Assen V Jablensky
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  ABSTRACT: Previous studies have found several electrophysiological endophenotypes that each co-varies individually with schizophrenia. This study extends these investigations to compare and contrast four electrophysiological endophenotype, mismatch negativity, P50, P300, and antisaccades, and analyze their covariance on the basis of a single cohort tested with all paradigms. We report a multivariate endophenotype that is maximally associated with diagnosis and evaluate this new endophenotype with respect to its application to genetic analysis. Group differences and covariance were analyzed for probands (n = 60), family members (n = 53), and control subjects (n = 44). Associations between individual endophenotypes and diagnostic groups, as well as between the multivariate endophenotype and diagnostic groups, were investigated with logistic regression. Results from all four individual endophenotypes replicated previous findings of deficits in the proband group. The P50 and P300 endophenotypes similarly replicated significant deficits in the family member group, whereas mismatch negativity and antisaccade measures showed a trend. There was minimal correlation between the different endophenotypes. A logistic regression model based on all four features significantly represented the diagnostic grouping (chi(2) = 32.7; p < .001), with 80% accuracy in predicting group membership. A multivariate endophenotype, based on a weighted combination of electrophysiological features, provides greater diagnostic classification power than any single endophenotype.
  Biological Psychiatry 08/2006; 60(1):1-10. · 8.28 Impact Factor
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  Available from: gla.ac.uk

  Article: EEG-dependent ERP recording: using TMS to increase the incidence of a selected pre-stimulus pattern.

  Gregory W Price
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  ABSTRACT: EEG dependent event-related potential (ERP) recording (interactive ERP) is an extension to ERP paradigms whereby stimuli are initiated in response to a selected pattern of background EEG. This form of recording is critically dependent upon the incidence of the particular pattern of interest. We introduce here a process that modifies the EEG in a predictable manner so as to increase the incidence of a particular pattern. Transcranial magnetic stimulation (TMS) stimuli are applied in response to a selected pattern of pre-TMS activity, and the post-TMS response is characterized by the incidence of a defined pattern of EEG activity. Analysis of validation test results obtained with the TMS modification part of the process verifies an increased incidence of the response pattern after TMS stimuli, compared with placebo stimuli. The TMS modification procedure is then combined with interactive ERP recording in a two step process to affect the ERP response to sensory stimuli. The post-TMS pattern from the first step becomes the pre-stimulus pattern of the interactive ERP recording in the second step. The TMS modified interactive ERP (TMIERP) process is illustrated here using an auditory oddball paradigm. The amplitude of the P300 peak obtained using this process was significantly higher than that obtained using the standard auditory oddball paradigm.
  Brain Research Protocols 03/2004; 12(3):144-51. · 1.82 Impact Factor