Phase locking (PL) of the early gamma band response to object (red) and non-sense object (blue) stimuli.

<p>Data from stimulus Set A (schematic black and white line drawings) are shown in the left column. Data from stimulus Set B (natural colored images) are shown in the right column. The top row shows topographic maps of the averaged phase locking from all conditions between 60 and 140 ms. In the second row, PL for the speeded response task is shown. In the third row, PL for the delayed response task is shown. All time course data are taken from Pz. Note, that PL after presentation of object stimuli is enhanced only if participants need to perform a speeded response. Response frequencies were determined from the time range 60 to 140 ms after stimulus onset. Asterisks mark significant differences that are described in the text, n.s. denotes nonsignificant differences. Stimulus onset is at 0 ms.