Effects of odor on emotion, with implications

Abstract

The sense of smell is found widely in the animal kingdom. Human and animal studies show that odor perception is modulated by experience and/or physiological state (such as hunger), and that some odors can arouse emotion, and can lead to the recall of emotional memories. Further, odors can influence psychological and physiological states. Individual odorants are mapped via gene-specified receptors to corresponding glomeruli in the olfactory bulb, which directly projects to the piriform cortex and the amygdala without a thalamic relay. The odors to which a glomerulus responds reflect the chemical structure of the odorant. The piriform cortex and the amygdala both project to the orbitofrontal cortex (OFC) which with the amygdala is involved in emotion and associative learning, and to the entorhinal/hippocampal system which is involved in long-term memory including episodic memory. Evidence that some odors can modulate emotion and cognition is described, and the possible implications for the treatment of psychological problems, for example in reducing the effects of stress, are considered.

Audio–visual and olfactory–visual integration in healthy participants and subjects with autism spectrum disorder

“…Comparing the networks linked to the integration of visual and olfactory information, as opposed to the integration of visual and acoustic information (OV – O – V > AV – A – V), we noticed increased activation in the right fusiform gyrus and the left lingual gyrus as well as activation in the right amygdala. The observation of amygdala activation is in line with the fMRI studies in which olfactory processing has been seen to elicit activation in the orbitofrontal regions as well as the piriform cortex including the amygdala, with amygdala activation in particular having been seen to be strongly triggered by odors (Costafreda et al, ; Kadohisa, ; Seubert et al, ). The amygdala, which receives a direct input from the olfactory bulb (Kadohisa, ), is assumed to play a role in evaluative behavior and affective response within associative learning, the encoding, for instance, of positive or negative cues (Schoenbaum, Chiba, & Gallagher, ; Seubert et al, ).…”

Dissociation of the Role of Infralimbic Cortex in Learning and Consolidation of Extinction of Recent and Remote Aversion Memory

“…Memory for odors that are associated with intense emotional experiences is often strongly engraved and resistant to decay over long intervals (Sullivan et al, 2000). Similarly, it was previously suggested that odors are more likely to affect memory than other sensory modalities or experiences (Engen 1973;Chu and Downes, 2000;Kadohisa, 2013). Furthermore, the robustness of trauma-related smells was shown to trigger symptoms in patients with posttraumatic stress disorders (see, eg, Vermetten and Bremner, 2003).…”

Improved low-cost, MR-compatible olfactometer to deliver tobacco smoke odor

“…Because the olfactory nerve has a direct connection to the limbic system (Kadohisa, 2013), odors are potent cues that evoke strong emotional responses (Buck and Axel, 1991), which makes them very important in cue-induced craving (Schneider et al, 2001). MR imaging modalities have been used to explore a wide range of tobacco-related effects, but despite this, smoking studies rarely employ olfactory cues.…”

“…Olfaction is likely an important sense for motivation and emotion, as the first cranial (olfactory) nerve synapses directly on to the limbic region of the central nervous system (c.f., Kadohisa, 2013). Olfactory stimuli are extremely salient (Herz et al, 2004), and because the responses to odor cues are nearly instantaneous, it is not feasible to expose individuals to odors outside of the scanner suite and then move them into the bore of the magnet for scanning.…”