Dissociation between phase-locked and nonphase-locked alpha oscillations in a working memory task.

TY - JOUR

T1 - Dissociation between phase-locked and nonphase-locked alpha oscillations in a working memory task.

AU - Freunberger, Roman

AU - Fellinger, Robert

AU - Sauseng, Paul

AU - Gruber, Walter

AU - Klimesch, Wolfgang

PY - 2009

Y1 - 2009

N2 - The functions of human alpha oscillations ( approximately 10 Hz) were related to cognitive processes such as memory and top-down control. Recent models suggest that alpha phase serves as a mechanism especially relevant for the timing of neural activity, whereas alpha amplitude is important for the inhibition of task-irrelevant brain areas. This study investigates directly the influence of top-down modulation on phase-locked and nonphase-locked alpha rhythms. We conducted an EEG experiment where subjects performed a working memory task. In the encoding phase of the task subjects had to learn presented pictures of nonliving objects that could later be asked to be retrieved. We varied the top-down modulation by including cues indicating either to remember or to forget (not to remember) the next following item. Spectral analyses showed that nonremember cues elicited pronounced alpha amplitude increase compared to remember cues. Furthermore, phase-locking in low frequencies, especially in the alpha range (7-12 Hz), was stronger for remember as opposed to not-to-remember items. In conclusion, we propose that alpha amplitude reflects top-down modulated inhibition and that alpha phase is important for the exact timing of neural activity and can be related to binding processes.

AB - The functions of human alpha oscillations ( approximately 10 Hz) were related to cognitive processes such as memory and top-down control. Recent models suggest that alpha phase serves as a mechanism especially relevant for the timing of neural activity, whereas alpha amplitude is important for the inhibition of task-irrelevant brain areas. This study investigates directly the influence of top-down modulation on phase-locked and nonphase-locked alpha rhythms. We conducted an EEG experiment where subjects performed a working memory task. In the encoding phase of the task subjects had to learn presented pictures of nonliving objects that could later be asked to be retrieved. We varied the top-down modulation by including cues indicating either to remember or to forget (not to remember) the next following item. Spectral analyses showed that nonremember cues elicited pronounced alpha amplitude increase compared to remember cues. Furthermore, phase-locking in low frequencies, especially in the alpha range (7-12 Hz), was stronger for remember as opposed to not-to-remember items. In conclusion, we propose that alpha amplitude reflects top-down modulated inhibition and that alpha phase is important for the exact timing of neural activity and can be related to binding processes.

M3 - SCORING: Zeitschriftenaufsatz

VL - 30

SP - 3417

EP - 3425

JO - HUM BRAIN MAPP

JF - HUM BRAIN MAPP

SN - 1065-9471

IS - 10

M1 - 10

ER -