Figure 1.

Intranasal electrical stimulation modifies but does not generate olfactory perception. (A) An endoscope (green arrow) was used to guide the electrode through an endoscopic working channel. Two Teflon tubes were positioned at the entrance of the stimulated nostril: one for delivering odors from an olfactometer (blue arrow), and another for measuring nasal airflow (red arrow). (B) A schematic of electrode placement within a sagittal section of the human nasal cavity, including the middle turbinate (MT), the superior turbinate (ST), and the olfactory cleft (C). (C) An endoscopic view inside the right nostril. The shiny pear-shaped body in the nostril is the MT. The pure-silver stimulating macro-electrode shows up as green in the image. (D) Perception induced by electrical stimulation. Percentage of stimulated subjects (n = 50) that reported: no sensation (gray); flashes of light (yellow); tingling at the reference electrode (green); or generalized intranasal somatosensory sensations such as electrical current (light blue), pinpricks (blue), and cooling (dark blue). Not one subject reported perception of odor. (E) Odor perception altered by electrical stimulation (n = 16). Each bar reflects the ratio between mean pleasantness rating given by a subject during electrical stimulation and sham. A mean of 1 implies no difference between the terms. An average lower than 1 implies reduced pleasantness during electrical stimulation. Inset contains the averaged data in bar representation, error bars are standard error of the mean (s.e.m).