Activation, travel distance, and environmental change influence food carrying in rats with hippocampal, medial thalamic and septal lesions: implications for studies on hoarding and theories of hippocampal function.

Rats transport food from exposed areas to covered areas where they eat it or leave it. Although there is evidence that limbic structures play a role in food transport, their role is controversial. Here it was found that although many rats with large hippocampal, septal/diagonal band of Broca or dorsomedial thalamic lesions did not carry food but ate it where they found it, a few presentations of an auditory stimulus could restore food carrying. Once restored, most features of food carrying in hippocampal rats were normal in relation to food presentation schedules, deprivation levels, ambient illumination, circadian cycles, food size, and eating times. Nevertheless, food carrying impairments re-emerged when the testing environment was changed. Hippocampal rats were also excessively responsive to increases in travel distance and stopped carrying food at distances over which control rats would still carry large food pellets. Auditory stimulation did not restore food carrying over long travel distances. The findings that sensory stimulation, environmental change, and travel distance influence food carrying probabilities in rats with limbic system lesions is discussed in relation to research on limbic control of food hoarding and theories of limbic system function.