Theta-band activity in hippocampus after an event seems to be crucial for learning. A study on the topic also proved that the absence of theta facilitated learning a simple task while training during theta had no effect on learning. Hippocampus is a brain structure that has a critical role in mammalian learning. The identification of different hippocampal states is based on the oscillatory properties of electrophysiological activity. Traditionally, rhythmic slow activity, theta, has been linked to attention, whereas transient bursts of synchronized neuronal firing, ripples, have been connected to the consolidation of recent experiences.