Fig. 2.

Left-hand panels. Density of Fos-positive units (counts mm⁻²) counted in the cortical and striatal regions: (A) infralimbic (ILPFC), prelimbic (PLPFC) and orbital (OPFC) prefrontal cortex; (B) nucleus accumbens core (AcbC) and medial and lateral portions of the nucleus accumbens shell (AcbS); (C) dorsomedial (DMCP) and dorsolateral (DLCP) caudate-putamen. Columns show the group mean data (+SEM) in each area for the rats trained under the variable-interval (VI) 75-s schedule (empty columns) and the fixed-interval peak procedure (FIPP) 30-s (filled columns). Significant difference between the groups, * p < 0.05. Right-hand panels. Diagramatic representation of the areas selected for counting Fos-positive units (three coronal sections at AP locations, measured from bregma, as indicated; modified from Paxinos and Watson [22]).