Animals build a model of their surroundings on the basis of information gathered during
exploration. Rearing on the hindlimbs changes the vantage point of the animal, increasing
the sampled area of the environment. This environmental knowledge is suggested to
be integrated into a cognitive map stored by the hippocampus. Previous studies have
found that damage to the hippocampus impairs rearing. Here, we characterize the operational
state of the hippocampus during rearing episodes. We observe an increase of theta
frequency paralleled by a sink in the dentate gyrus and a prominent theta-modulated
fast gamma transient in the middle molecular layer. On the descending phase of rearing,
a decrease of theta power is detected. Place cells stop firing during rearing, while
a different subset of putative pyramidal cells is activated. Our results suggest that
the hippocampus switches to a different operational state during rearing, possibly
to update spatial representation with information from distant sources.
