Table 1.
Overview of electrical stimulation on the olfactory system
| Source (year) | Study population | Methods | Results |
|---|---|---|---|
| Electrical olfactory activation in animals | |||
| Ottoson (1959) [53] | Frogs | eStim nasal mucosal stimulation | In the area of the olfactory mucosa → potential changes in OB |
| Coelho and Costanzo (2016) [14] | 8 Rats |
Olfactory stimuli recording of neuronal activity in the OB (n = 8) eStim of the OB (n = 4) |
Localized activation patterns in the OB by different odor stimuli eStim at different localizations of the OB → localized activation of the OB using evoked potentials |
| Dong et al. (2013) [22] | 44 Rats |
eStim by 16-channel micro-electrode at the OB Presentation of five different odors |
Derivation of odor-dependent activation patterns of the ORN Scent identification by decoding algorithm of the activation patterns (n = 4) |
| Electrical stimulation of the human olfactory mucosa | |||
| Aronsohn (1886) [3] | 4 Healthy individuals | Bilaterally endonasally placed electrode | Odor perception “match” (n = 2) |
| Uziel (1973) [71] | 21 (Healthy individuals and ENT patients) | eStim with various electrodes (Ag and Ag-AgCl-NaCl) |
Anodal stimulation → odor perception “almond” (n = 5), “burnt” (n = 3), vanilla (n = 1) and “purulent” (n = 1). Ag-AgCl-NaCl: no olfactory sensation, but sensation of pain |
| Straschill et al. (1983) [68] | 10 Healthy individuals, 5 patients with epilepsy | eStim and presentation of olfactory stimuli |
Suppression of olfactory sensation Cacosmic olfactory impressions without odor stimulus (n = 3) |
| Ishimaru et al. (1997) [34] | 5 Healthy individuals | eStim via Ag electrode | No generation of olfactory sensations |
| Weiss et al. (2016) [76] | 60 Healthy individuals |
eStim of different nasal sections fMRI (n = 20) |
Modulation of presented olfactory stimuli only in eStim of olfactory mucosa. No generation of olfactory sensations by eStim |
| Electrical stimulation of the OB in humans | |||
| Penfield and Jasper (1954) [54] | 5 Patients with epilepsy | Intraoperative eStim of the OB in the awake patient | Unpleasant odor sensation |
| Holbrook et al. (2019) [31] | 5 Patients with CRS | Transethmoidal eStim of the OB | Odor perceptions (n = 3): onion-like, antiseptic, sour, fruity, bad |
| Electrical stimulation of the cortex and other brain areas in humans | |||
| Kumar et al. (2012) [36] | 16 Children with epilepsy | eStim via subdural electrodes | Stimulation near OB or olfactory tract → olfactory sensations (n = 13) |
| Bérard et al. (2020) [5] | 8 Individuals with epilepsy | eStim via deep brain electrode | Stimulation at medial orbitofrontal cortex → olfactory perception (n = 5) |
| Mazzola et al. (2017) [42] | 221 Individuals with epilepsy | eStim of the insula via deep brain electrodes | Olfactory sensations from stimuli at mediodorsal insula |
| Andy (1967) [1] | 1 Individual with epilepsy | eStim amygdala and hippocampus (right-sided) | Electrostimulation of amygdala → olfactory sensation (foul), electrostimulation of hippocampus without olfactory sensation |
| Nashold and Wilson (1970) [50] | 5 Individuals with neurological disease | eStim via depth electrodes on the awake patient | Electrostimulation of the thalamus → various olfactory impressions (rubber, smoky/burnt, chloroform, clove) |
Ag silver, Ag-AgCl-NaCl silver–silver chloride–sodium chloride, CRS chronic rhinosinusitis, eStim electrical stimulation, fMRI functional magnetic resonance imaging, n number, OB olfactory bulb