Phase-locking and amplitude modulations of EEG alpha: Two measures reflect different cognitive processes in a working memory task.
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Phase-locking and amplitude modulations of EEG alpha: Two measures reflect different cognitive processes in a working memory task. / Herrmann, Christoph S; Senkowski, Daniel; Röttger, Stefan.
In: EXP PSYCHOL, Vol. 51, No. 4, 4, 2004, p. 311-318.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Phase-locking and amplitude modulations of EEG alpha: Two measures reflect different cognitive processes in a working memory task.
AU - Herrmann, Christoph S
AU - Senkowski, Daniel
AU - Röttger, Stefan
PY - 2004
Y1 - 2004
N2 - 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.
AB - 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.
M3 - SCORING: Zeitschriftenaufsatz
VL - 51
SP - 311
EP - 318
JO - EXP PSYCHOL
JF - EXP PSYCHOL
SN - 1618-3169
IS - 4
M1 - 4
ER -