Animal models of amnesia: The effects of hippocampal lesions on olfactory and spatial memory in the rodent
Humans with damage to the hippocampus and adjacent structures exhibit profound impairments in the formation of new memories. Recent work in monkeys has suggested that the hippocampus is likewise necessary for normal memory capacity, or span. Inspired by these findings, we attempted to develop a span task for rodents. Our results were surprising: Rats readily remembered a large number of odours, and were able to do so even without a hippocampus. However, when tested in a spatial version of the task, rats with hippocampal damage were significantly impaired. These results suggest that rats have a large capacity for recognising odours, and do not need the hippocampus for this type of memory. Rats appear to have less of a capacity for recognising spatial locations, and the hippocampus is necessary for this type of spatial recognition memory.