Gamma band activity in an auditory oddball paradigm studied with the wavelet transform
Gurtubay I.G., Alegre M. [SP], Labarga A., Malanda A., Iriarte J., Artieda J. [SP]
Clinical Neurophysiology Unit, Department of Neurology, Clínica Universitaria, Facultad de Medicina, Universidad de Navarra, Pamplona, Spain
Magazine: Clinical Neurophysiology
Date: Jul 1, 2001Neurophysiology [SP]
To examine the characteristics of evoked and induced gamma band oscillatory responses occurring during P300 development in an auditory oddball paradigm.
A time-frequency analysis method was applied to an auditory oddball paradigm in 7 healthy subjects. This method combines a multiresolution wavelet algorithm for signal extraction and the Gabor transform to represent the temporal evolution of the selected frequency components. Phase-locked or evoked activity and also non-phase-locked activity were computed for both standard and target stimuli.
The gamma band frequency components differed between target and non-target stimuli processing. The study showed an early and mainly phase-locked oscillatory response appearing around 26--28 ms after both standard and target stimuli onset. This response showed a spectral peak around 44 Hz for both stimuli. A late oscillatory activity peaking at 37 Hz with a latency around 360 ms was observed appearing only for target stimuli. The latency of this late oscillatory activity had a high correlation (P=0.002) to the latency of the P300 wave.
EEG signal analysis with wavelet transform allows the identification of an early oscillatory cortical response in the gamma frequency range, as well as a late P300-related response.
CITATION Clin Neurophysiol. 2001 Jul;112(7):1219-28
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