02176nas a2200217   4500008004100000022001400041245009600055210006900151260001200220300001400232490000800246520147500254653003601729653002901765653003401794653001001828653002201838100002601860700002401886856004801910       2004                        eng d  a0378-595500aSeparating stimulus-locked and unlocked components of the auditory event-related potential.0 aSeparating stimuluslocked and unlocked components of the auditor  c07/2004  a111–1200 v1933 aA new method is evaluated for separating stimulus-locked and unlocked components of auditory event-related EEG activity. The new method uses a regression based subtraction procedure as a way to account for latency and amplitude variability within individual trials. It was applied using the oddball paradigm under conditions of active and passive listening and analyzed as spectral correlations (normalized differences) between post-stimulus epochs of standard, target or deviant stimulus conditions and silent pre-stimulus baseline activity. The regression-subtraction procedure accounted for a greater amount of variance than a method that uses linear subtraction alone. The major component of the response to auditory stimulation was an event-related synchronization in the delta and theta (2-4 Hz) frequency range. Event-related desynchronizations were also observed in the 10 Hz (alpha/mu) and in the 20-30 Hz (beta) frequency range. The regression based subtraction procedure provides better separation of stimulus-locked and unlocked components of event-related EEG activity then linear subtraction alone. Stimulus-locked and unlocked components show different patterns and topographies of effects related to attention and active discrimination. Studying both stimulus-locked and unlocked components of event-related EEG reactivity in the frequency domain provides a more comprehensive account of dynamic brain activity subserving auditory information processing.10aevent-related desynchronization10aevent-related potentials10aevent-related synchronization10aphase10aspectral dynamics1 aMcFarland, Dennis, J.1 aCacace, Anthony, T.  uhttp://www.ncbi.nlm.nih.gov/pubmed/1521932602161nas a2200241   4500008004100000022001400041245009800055210006900153260001200222300001200234490000800246520137200254653002701626653003301653653003601686653003401722653001801756653002201774653002501796100002401821700002601845856004801871       2003                        eng d  a0378-595500aSpectral dynamics of electroencephalographic activity during auditory information processing.0 aSpectral dynamics of electroencephalographic activity during aud  c02/2003  a25–410 v1763 aDynamics of electroencephalographic (EEG) activity during auditory information processing were evaluated in response to changes in stimulus complexity, stimulus discriminability and attention using the oddball paradigm. In comparison to pre-stimulus baseline conditions, auditory stimulation synchronized EEG activity in delta, theta and alpha frequency bands. Event-related synchronization (ERS) effects were greatest at approximately 3 Hz (theta frequency band), and their magnitude depended on stimulus and task demands. Event-related desynchronization (ERD) of EEG activity was observed in the beta frequency band. This effect was greatest at approximately 21 Hz but occurred only for easily discriminable stimuli in attention-related target conditions. Because active discrimination tasks also required a button-press response with the right hand, ERDs involved more complex responses that may be related to a combination of perceptual, motor and cognitive processes. These results demonstrate that oddball and attention-related EEG responses to auditory stimulation could be characterized in the frequency domain. The specific design and analysis features described herein may prove useful since they provide a simple index of the brain's response to stimulation while at the same time provide powerful information not contained in typical time domain analysis.10aElectroencephalography10aevent-related brain dynamics10aevent-related desynchronization10aevent-related synchronization10apsychophysics10aspectral analysis10atime domain analysis1 aCacace, Anthony, T.1 aMcFarland, Dennis, J.  uhttp://www.ncbi.nlm.nih.gov/pubmed/12583879