Figure 3.

Electrode placement. A, Left side shows a formol-thionin-stained section from the OFC on an implanted animal (approximately bregma +3.5 mm AP). The arrowhead points to the lacunae near the end of a tetrode, created by running DC through the tetrode before perfusing the animal. The asterisk (*) indicates a visible tetrode track. Right side shows the placement of tetrodes in all nine animals (indicated by color) that varied between +3.2 and +4.0 mm on the AP axis. B, Left side shows a formol-thionin-stained section in the hippocampus of an animal implanted (approximately bregma −3.8 mm AP). The arrowhead indicates the hippocampal electrode. Right side indicates the placement of the hippocampal electrodes in the six implanted animals (indicated by color). Electrode placement varied between −4.0 and −3.5 mm AP, but placements are shown collapsed on a single section. The black line coronal section diagrams are modified from Paxinos and Watson (1998).