Olfactory Cognition : The Case of Olfactory Imagery

Sammanfattning: The capacity to form olfactory images has received less attention than the formation of visual and auditory images. The evidence in favor of such ability is also inconsistent. This thesis explored some of the characteristics of olfactory imagery through three empirical studies. Study I investigated the effects of blocking spontaneous sniffing during olfactory imagery. The results indicated that the prevention of spontaneous sniffing reduced olfactory but not visual imagery capacity. Study II studied the relation between olfactory awareness (as indexed by olfactory dreams, olfactory imagery, and olfactory interest) and olfactory functions (i.e., odor threshold, episodic odor memory, and odor identification). The main findings were that compared to low, high olfactory awareness was associated with better episodic odor memory and identification, but not with higher olfactory sensitivity. Study III investigated the neural correlates of odor evoked autobiographical memories (OEAMs) as (a) a function of cue modality (i.e., odors and their verbal referents), and (b) a function of memory remoteness. The results from Study III showed that OEAMs activated regions generally associated with autobiographical memory. In addition, verbally cued OEAMs were associated with activity linked to olfactory imagery. Odor cues activated the limbic and temporal polar regions more than verbal cues; a result that may explain the phenomenological differences found between the cued memories. Moreover, OEAMs from the first decade of life were associated with higher activity in the secondary olfactory cortex, whereas memories from young adulthood were related to areas linked to semantic memory processing. Taken together these studies favor the notion of a human capacity to form olfactory images.