Figure 4.

Selective inhibition of ventral hippocampus projections to the nucleus accumbens shell promotes the use of action–outcome contingencies. (A) Timeline of experimental procedures. Surgical and training procedures were identical to those described in Figure 1B, except that nucleus accumbens shell cannula were implanted at the time of surgery. (B) Photomicrgraph showing ventral hippocampus terminals within the nucleus accumbens. (C) Composite of injections indicating the spread of the Gi-DREADD within the ventral hippocampus (left) and accumbens cannula placements (right). (D) Acquisition of sucrose seeking. (E) Under control conditions, mice expressing the Gi-DREADD were insensitive to changes in action–outcome contingencies. Selective inhibition of the ventral hippocampus to nucleus accumbens shell promoted the use of action–outcome contingencies to mediate reward seeking. (F) Selective inhibition of the ventral hippocampus to the nucleus accumbens shell reduces consummatory behavior in both nondegraded and degraded test sessions.