Figure 2.

Timeline of experimental events in mice. (Top row) Mice were trained to nose poke for food pellets; conditioned aversion was then induced by pairing the food pellets with LiCl, causing operant avoidance. We tested whether DCS could facilitate the extinction of this avoidance when mice were presented with pellets in the absence of LiCl. DCS was administered following the first three extinction conditioning sessions, then the mice were further tested in the absence of drug to assess the long-term effects of DCS, if any. Phospho-ERK1/2 and dendritic spine imaging followed. (Bottom row) In our final experiment (Figure 5), the mice were extensively trained to develop nose-poking habits. Conditioned aversion was induced, then nose poking was quantified. DCS treatment accompanied these test sessions. DCS, d-cycloserine.