Chen Lihan's research group published an article in Chemical Senses to show that the application of trigeminal nerve mixed olfactory agent stimulation to the human nostrils can induce perceptual bias in sound position

For a long time, the nasal chemical senses have been considered unimportant senses, and it has even been suggested that the information people get through smell is insignificant, and the use of smell is considered to be a substitute for losing other senses
.
However, in fact, the sense of smell plays a vital role
in human life.
In daily life, smell information "guides" our behavior, affects our feeding behavior, prompts dangerous information about the external environment, helps us locate and navigate, and promotes people's social communication
.

For spatial positioning navigation, humans do not rely entirely on a single sensory information, although people are considered visual navigators, but in fact humans can use arbitrary sensory information to evaluate the target position
in space.
Therefore, although people will give preference to visual information in spatial navigation or spatial positioning, information input from other senses will also affect the final navigation or positioning results
.

The Ventriloquist effect was originally used to describe the effect
of visual information affecting auditory position perception.
In this study, the authors used the highly sensitive paradigm of abdominal language effect to investigate whether unilateral odor input affects participants' perception of sound position
.
The study recruited 41 participants (15 males and 26 females, aged 22.
6 ± 3.
2 years) who passed the Chinese olfactory recognition test, and the odor stimulation was stimulated by 10% volume fraction phenylethanol (only activates the nasal olfactory nerve pathway), 1% volume fraction menthol (activates both the nasal olfactory pathway and the intranasal trigeminal nerve pathway) and propylene glycol (control group and solvent).

。 During the experiment, the participants would hear a pure tone lasting 1.
5s during the inhalation stage (odor input on one side, control group on the other side), and the position information of the sound was simulated by the head transfer function, and the sound position angles were 20°, -10°, -5° and the center on both sides, with a distance of 1m
.
Participants were tasked with determining whether sounds appeared on the left or right and reporting their confidence in making judgments (Figure 1).

The data were combined by the Sigmoid function to calculate PSE, and the results showed that the one-sided phenethanol input did not affect the participant's judgment of the direction of the sound, but the one-sided menthol input would bias the position of the perceived sound to the direction of
the odor.
Based on this result, the authors speculate that if and only if odor stimulates the intranasal trigeminal nervous system, the perception of sound position can be systematically shifted
.
This study extends the multisensory abdominal language effect from non-chemical sensory pathways to chemical sensory channels, and suggests that the neural properties of odor itself (pure olfactory odor or olfactory trigeminal mixed odor) may play a role
in odor abdominal language effects.

Figure 1.
An experimental paradigm for sound localization
.
Participants heard sounds
while inhaling odors.
The sound orientation is defined as the angle at which it is deflected from the sagittal plane of the head ('-' means to the left, '+' means to the right).

ITI: length of test interval; Determining the direction: left or right
.
Confidence level: From 1 to 7 (1 means "just guessing" and 7 means "very confident"
.
) The higher the score, the more confident you are).