Hippocampal Activation During Gustatory Stimulation

Abstract:
Although the functions of the human hippocampus have been intensively investigated, few studies have examined how the human hippocampus responds to different types of sensory stimuli. We here report data from three H ₂ O ¹⁵ PET studies, in which subjects tasted salty, sour or sweet gustatory solutions. In each study, tasting the gustatory solution increased activity in the hippocampus relative to attempting to taste an equivalent volume of water. These hippocampal activations occurred in the absence of any explicit mnemonic task demands. This contrasts with neuroimaging studies of visual, auditory and somatosensory perception which rarely demonstrate significant increases in human hippocampal activity. The ability of gustatory stimuli to activate hippocampal processing may relate to the biological importance of learning information about foodstuffs. This ability may also explain the 'Proust phenomenon,' in which gustatory sensations evoke vivid, hedonically-valenced, autobiographical memories.