Predictive goal coding by somatostatin-expressing interneurons is rapidly updated by current experience

To select appropriate behaviour, individuals need to rely on the encoding of relevant features within their environment in the context of current and past experiences. This function has so far been related to goal-associated activity patterns of hippocampal principal cells. By applying single unit recordings of optogenetically identified somatostatin-expressing interneurons (SOMIs) in the hippocampal dentate gyrus of head-fixed mice trained on a spatial goal-oriented reward-learning task in a virtual reality, we show that in expert mice characterized by goal anticipatory behaviour, SOMIs activity temporally precedes reward-locations. Predictive goal-coding by SOMIs is lost after translocation of learned goals to novel previously unrewarded sides resulted in rapid reduction of anticipatory behaviour, and rapid reconfiguration of SOMI activity to times after reward onset in association with reward consumption at novel goal-sides. Chemogenetic silencing of SOMIs caused a loss in memorizing that trained goal-sides are no longer available. Thus, our data show a so far unrecognized ability of SOMIs to flexibly encode goal-locations depending on current and past experiences to bias behavioral outcomes.