title: Prestimulus EEG alpha activity reflects temporal expectancy.
abstract: Since prestimulus EEG alpha activity has recently been considered to convey prestimulus top-down processing, we investigated whether prestimulus alpha activity reflects temporal expectancy of upcoming stimulation even under the non-classical contingent negative variation (CNV) paradigm. EEG was recorded from 16 subjects performing a color and a shape discrimination task manipulated with constant and variable inter-stimulus interval (ISI) conditions. The power of oscillatory activity was investigated by convolving the EEG signals with Morlet wavelets. The constant ISI condition yielded significantly shorter reaction times than the variable ISI condition, indicating more efficient preparation for upcoming stimuli during the constant ISI. We found significantly higher prestimulus alpha activity in the constant ISI condition than in the variable ISI condition, but no significant CNV even in the constant ISI condition. Such a reflection of temporal expectancy in the prestimulus alpha activity corroborates that the prestimulus top-down mental state for preparing upcoming task-performance is considerably reflected in the prestimulus ongoing alpha activity.
authors.affiliation: Brain Korea 21 Project for Medical Science, Yonsei University, College of Medicine, Seoul, Republic of Korea.
authors.forename: Byoung-Kyong
authors.initials: BK
authors.lastname: Min
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Park
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Kim
authors.forename: Joong Il
authors.initials: JI
authors.lastname: Kim
authors.forename: Jae-Jin
authors.initials: JJ
authors.lastname: Kim
authors.forename: Hae-Jeong
authors.initials: HJ
authors.lastname: Park
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D001931:Brain Mapping; D003265:Contingent Negative Variation / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013057:Spectrum Analysis; D013997:Time Factors