Eeg alpha phase at stimulus onset significantly affects the amplitude of the P3 ERP component

Abstract. It has been demonstrated in numerous experiments that oscillatory EEG responses in the alpha frequency band (8-12 Hz) increase with memory load during the retention interval in working memory tasks. However, the findings diverge with respect to which measurement of alpha activity is influenced by memory processes. Here, we differentiate between evoked and total alpha activity in order to separate effects of phase-locking and amplitude modulation. We present data from a delayed-matching-to-sample task (S1-S2 paradigm) for which we compared EEG alpha responses between a perception and a memory condition. Increased total alpha activity was found in the retention interval for the memory as compared to the perception condition. Evoked alpha activity, however, did not differentiate between memory and perception conditions but, instead, was increased for the more complex condition of processing non-Kanizsa figures as compared to Kanizsa figures. Thus, our results demonstrate a functional differentiation between evoked and total alpha activity. While alpha phase locking seemed to be influenced mainly by task complexity, alpha amplitude clearly reflected memory demands in our paradigm.

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EEG alpha phase shifts during transition from wakefulness to drowsiness

International Journal of Psychophysiology ◽

10.1016/j.ijpsycho.2012.04.012 ◽

2012 ◽

Vol 86 (3) ◽

pp. 195-205 ◽

Cited By ~ 11

Author(s):

Aleksandar Kalauzi ◽

Aleksandra Vuckovic ◽

Tijana Bojić

Keyword(s):

Phase Shifts ◽

Alpha Phase ◽

Eeg Alpha

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The triple-flash illusion reveals a driving role of alpha-band reverberations in visual perception

10.1101/093500 ◽

2016 ◽

Cited By ~ 1

Author(s):

Rasa Gulbinaite ◽

Barkin İlhan ◽

Rufin VanRullen

Keyword(s):

Phase Locking ◽

Threshold Level ◽

Alpha Phase ◽

Stimulus Onset ◽

Impulse Response Functions ◽

Alpha Band ◽

Trial Basis ◽

The Subject ◽

Onset Asynchrony

ABSTRACTThe modulatory role of spontaneous brain oscillations on perception of threshold-level stimuli is well established. Here, we provide evidence that alpha-band (7-14 Hz) oscillations not only modulate but also can drive perception. We used the “triple-flash” illusion: Occasional perception of three flashes when only two spatially-coincident veridical ones are presented, separated by ~100 ms. The illusion was proposed to result from superposition of two hypothetical oscillatory impulse response functions (IRF) generated in response to each flash (Bowen, 1989). In Experiment 1, we varied stimulus onset asynchrony (SOA) and validated Bowen's theory: the optimal SOA for illusion to occur was correlated, across subjects, with the subject-specific IRF period. Experiment 2 revealed that pre-stimulus parietal alpha EEG phase and power, as well as post-stimulus alpha phase-locking, together determine the occurrence of the illusion on a trial-by-trial basis. Thus, oscillatory reverberations create something out of nothing – a third flash where there are only two.

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