Yes, the olfactory bulb is well connected to the amygdala and hippocampus (which is why certain aromas are highly evocative of emotional memories). They have a similar functional structure too.

The olfactory bulb contains about 2000 ‘glomeruli’: globular tangles of axons (from olfactory receptors) and dendrites (of neocortical mitral cells). Each glomerulus receives signals from hundreds or thousands of widely distributed receptor cells which each respond to the same chemical stimulus. A single glomerulus detects the presence of a particular odorant chemical. The majority of fragrances, however, are blends of different odorant chemicals and the differences can be represented as distinct patterns of activation across these glomeruli. The colorful diagram in Mori et. al's "The Olfactory Bulb: Coding and Processing of Odor Molecule Information" (Science, 1999) is reminiscent of the arrangement of keys on an accordion.

Similarly our complex human emotions comprise blends of different functional dispositions that can be triggered by the detection of simple patterns in perception or cognition, in all sorts of combinations. Specific combinations of smells evoke specific emotional memories or dispositions.

Yes, I agree Sam Brown.

Hello!

Just recently I found a paper which might be of interest for you:

E. A. Krusemark et al.; “When the Sense of Smell Meets Emotion: Anxiety-State-Dependent olfactory Processing and Neural Circuitry Adaption“, The Journal of Neuroscience, Vol.: 33 (39), S. 15324-15332; 2013

So there is scientific evidence that emotions can influence percieved intensity and quality of an odor. I didn't have the time to read the Paper in detail, but since this is a very recent publication you might find additional interesting references.

Excellent, thank you very much Christopher. This is highly appreciated.

The effect of emotions on perceived intensity and quality may only be one end of the stick as it were. I am interested to know if the reverse is true and that emotions can be changed by odours.

Dear Jerry, there is a lot of evidence that demonstrates that odours modify and even trigger emotions. Only, I would replace the word emotion with affect since I follow the idea that emotions are bodily responses as a result of affective processing, which in turn equals neural activity that can be directly elicited by olfactory input.

Hi Peter, is the effect of odours consistent, i.e. do they elicit the same effect in different people, or do people respond differently to the same odour? Has this been reviewed by anyone to your knowledge?

Hi Jerry and Peter, there are a number of papers out there from the late1990s and early 2000s that deal with the impact of odors on basic emotions as defined by Ekman. Some researchers claim that there is something as an emotional specificity of odors, meaning that a certain odor elicits a specific basic emotion, at least for pleasant odors. However, comparisons between autonomic correlates of the basic emotions and verbal reports demonstrated that unpleasant odors may elict one emotion on the physiological level and another one on the verbal level. Later on it has also been demonstrated that individual experience and preferences may modify the relation between odors and basic emotions and that happiness and disgust are evoked far more often than the other basic emotions. In the light of what Peter has written in his first remark that odors are processed in regard to their affective value in the first place, this makes a lot of sense.

See our recent publication

Sincerely Yours

Pierre

Typically, it is considered that olfaction is initiated by the interaction of odoriferous molecules with olfactory sensory receptors in the olfactory epithelium. It is entirely valid only for the naïve animal that never been exposed to the odorant, and the odorant has no visual image or sound presentations. For example, if dogs are trained to the certain odorants accompanied with optical or acoustic signals, or have inherited the knowledge of the odorant (like an odor of fire) the process of olfaction involves other modalities like vision, hearing, memory, thinking, analyzing, etc. These additional odor information processing associated with training and learning can be investigated if the olfaction can be evoked not by odorant molecules, but acoustic, visual, or memory impression of the odorant. The vocalization of “baked potato”, “rose” or “wood fire” evokes the perception of odors of these objects in the human. The visual images of the same objects make one to smell the same things. There is evidence that some odorants can modulate emotion and cognition. The piriform cortex and the amygdala both project to the orbitofrontal cortex that with the amygdala is involved in emotion and associative learning, and to the entorhinal/hippocampal system that is involved in long-term memory including episodic memory. Although, the entorhinal cortex collects and distributes information about olfactory memory and serves as a top-down modulator of olfactory cortical function. The medial and orbital parts of the frontal cortex are involved in the cognitive integration of all sensory stimuli in relation to prior experiences.