Figure 2.

Repetition enhancement and persistent delay activity. Average population activity (29 cells in prefrontal cortex) in response to the repetition of a stimulus inside (red curve) and outside (green curve) the neuron's receptive field. Vertical bars indicate the time of the first (sample) and the second stimulus presentation (match). The activity between sample and match as well as after the match offset, is significantly higher than baseline (persistent delay activity–indicated by the gray areas-). Although the authors do not analyse neural activity during match presentation, the repetition enhancement effect is apparent when both stimuli were presented inside the receptive field. Adapted from Meyer et al. (2007).