The role of the human hippocampus in odor-place associative memory

Hippocampal lesions in rodents impair both object-place and odor-place associative memory. Subjects with hippocampal damage have impaired associative memory such as object-place memory. Whereas studies have investigated some types of associative memory, no investigation has specifically examined odor-place associative memory in subjects with well-defined amnesia. It is unknown whether amnesic subjects with hippocampal damage would be impaired on an odor-place associative task. We investigated the effect of hippocampal damage in amnesic subjects with hippocampal atrophy on odor-place associative memory and recognition memory tasks. Amnesic and healthy comparison subjects matched for age and education were tested on an odor-place associative task, an odor recognition task, and a place recognition task. The odor-place associative task required subjects to associate 6 odors with 6 spatial locations on a board. The recognition tasks required subjects to identify the 6 odors and the 6 locations that were presented during the associative task. Amnesic subjects were impaired for odor-place memory and place recognition, but not odor recognition compared with comparison subjects. These results suggest that the human hippocampus is necessary for odor-place associative memory and spatial recognition memory. These data provide support for the idea that odor-place associative memory is mediated by the hippocampus in both humans and rodents, suggesting an evolutionary continuity in cognitive function assigned to the hippocampus.