Retention deficits after combined amygdalo-hippocampal and selective hippocampal resections in the monkey

In one experiment, monkeys with either combined amygdalo-hippocampal, or selective hippocampal or entorhinal resections, were impaired on a task which required both visual recognition of objects and retention of their reward-value. In a second experiment, monkeys with selective hippocampal resections were impaired on the same task in the tactual modality. In the last two experiments, monkeys with hippocampal, or entorhinal area resections, were impaired in retaining two-choice object discriminations at either 1 or 24 hr intervals. Thus, retention deficits can follow hippocampal damage in non-human primates, provided appropriate tasks are used.