Olfaction may be associated with spatial memory in humans and rely on the same regions of the brain, according to a study in Nature Communications.
It has been proposed that the sense of smell originally evolved to help animals navigate the environment. Currently, there is some evidence that olfactory identification may be associated with spatial memory (which involves learning the relationships between landmarks in an environment and building a cognitive map) however, this has not been tested directly.
Veronique Bohbot and colleagues sought direct evidence that olfactory identification and spatial memory are related to one another, and if so, whether this reflected shared brain regions. The authors found that in a group of 57 volunteers, participants who did well in a test to identify different odours also performed better at a ‘wayfinding’ task (in which they had to navigate between landmarks through a virtual town).
Using magnetic resonance imaging, the authors found that increased thickness of the left medial orbitofrontal cortex (mOFC) and volume of the right hippocampus of the brain predicted better performance on both tasks, suggesting that the same brain regions may underlie odour identification and spatial navigation ability. In additional tests, performance on both olfactory identification and spatial memory tasks was impaired in a group of nine patients who had suffered brain lesions affecting the mOFC. No such impairment was seen in nine separate patients with similar brain lesions that did not affect the mOFC.
Although further research is needed, the authors argue that the findings support the suggestion that the original function of the olfactory sense may have been to support cognitive mapping and spatial memory.