title: Single trial time-frequency domain analysis of error processing in post-traumatic stress disorder.
abstract: Error processing studies in psychology and psychiatry are relatively common. Event-related potentials (ERPs) are often used as measures of error processing, two such response-locked ERPs being the error-related negativity (ERN) and the error-related positivity (Pe). The ERN and Pe occur following committed error in reaction time tasks as low frequency (4-8 Hz) electroencephalographic (EEG) oscillations registered at the midline fronto-central sites. We created an alternative method for analyzing error processing using time-frequency analysis in the form of a wavelet transform. A study was conducted in which subjects with PTSD and healthy control completed a forced-choice task. Single trial EEG data from errors in the task were processed using a continuous wavelet transform. Coefficients from the transform that corresponded to the theta range were averaged to isolate a theta waveform in the time-frequency domain. Measures called the time-frequency ERN and Pe were obtained from these waveforms for five different channels and then averaged to obtain a single time-frequency ERN and Pe for each error trial. A comparison of the amplitude and latency for the time-frequency ERN and Pe between the PTSD and control group was performed. A significant group effect was found on the amplitude of both measures. These results indicate that the developed single trial time-frequency error analysis method is suitable for examining error processing in PTSD and possibly other psychiatric disorders.
authors.affiliation: Department of Bioengineering, University of Louisville, Louisville, KY, USA.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Clemans
authors.forename: Ayman S
authors.initials: AS
authors.lastname: El-Baz
authors.forename: Michael
authors.initials: M
authors.lastname: Hollifield
authors.forename: Estate M
authors.initials: EM
authors.lastname: Sokhadze
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011597:Psychomotor Performance; D011930:Reaction Time; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology / Q000523:psychology*; D058067:Wavelet Analysis