Figure 1.

Trial presentation. Animals were trained in pairs, where one animal belonged to the R+ and the other to the YC group. The occurrence of a ripple event was detected from the hippocampal LFP of the subject assigned to the R+ group by means of a simple brain–computer interface. A trial was presented simultaneously to both animals contingent upon the occurrence of a ripple in the R+ animal. Thus, subjects in both groups received identical training. The minimum intertrial interval was set to 15 s. For the R+ example, both the raw (top) and the bandpass-filtered (80–250 Hz, middle) signals are shown. In addition, a dashed line indicates the threshold set for the ripples in this animal. For the YC example (bottom), only the raw signal is shown. R, Ripple detection time window.