Acquisition and retention by hippocampal rats of simple, conditional, and configural tasks using tactile and olfactory cues: implications for hippocampal function.

Hippocampal rats were given simple, conditional, and configural tasks that required them to pull up strings to obtain food pellets. The tasks contrasted string size, odor, location, paired string size and location, or compounds of string size and odor. There was no anterograde or retrograde amnesia for the simple discriminations or for simple discrimination components of the other tasks. Hippocampal rats also learned conditional and configural tasks, although they were impaired on the configural task. Finally, the rats were impaired in postoperative retention of the conditional but not the configural task, although they displayed savings in relation to naive rats on the conditional task. The results do not support theories that the hippocampus is essential for conditional or configural learning but may support a modified form of configural theory in which the hippocampus contributes to, but is not essential for, learning or retention of configurations.