Table 1.
Characteristics of task-related taVNS studies that are included in the review.
| Study(author/year) | Sample size | Study design & protocol | Age(years) | Stimulationparameter | Symptom | Targetdisorder | taVNS effects |
|---|---|---|---|---|---|---|---|
| Colzato et al., 2018 (63) | taVNS: 40 Sham: 40 F: 50 |
Between Acute taVNS |
17-33 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Depression | Depressive disorders | Divergent thinking ↑ |
| Neuser et al., 2020 (64) | 81 (47 F) | Within Acute taVNS |
25.3(3.8) | taVNS: cymba conchae 1.28(0.58) mA sham: earlobe 1.82(0.63) mA 25Hz, 30s on 30s off |
Depression | Depressive disorders | Reward seeking ↑ |
| De Smet et al., 2021 (65) | taVNS: 42 Sham: 41 F: 66 |
Between Acute taVNS |
21.11(3.10) | taVNS: cymba conchae 1.37(0.81) mA sham: earlobe 1.89(0.89) mA 25Hz, 250μs, 30s on 30s off |
Depression | Depressive disorders | Negative emotion regulation ↑ |
| Ferstl et al., 2021 (66) | 82 (47 F) | Within Acute taVNS |
24.6(3.5) | taVNS: cymba conchae sham: earlobe 25Hz, 30s on 30s off |
Depression | Depressive disorders | Mood recovery↑ |
| Steenbergen et al., 2021 (67) | 73 (58 F) | Within Acute taVNS |
18-28 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Depression | Depressive disorders | Recognition of sadness ↓ |
| Koenig et al., 2021 (68) | 33 (27 F) adolescents with major depressive disorders | Within Acute taVNS |
14-17 | taVNS: concha sham: earlobe 0.5mA, 1Hz, 250μs, 30s on 30s off |
Depression | Depressive disorders | Attention to sad stimuli ↓ |
| Kraus et al., 2007 (38) | 6 (5 F) | Within Acute taVNS |
20-37 | taVNS: inner tragus sham: earlobe 8Hz, 20μs |
Depression | Depressive disorders | BOLD-signal in limbic brain areas↓
Subjective well-being ↑ |
| Burger et al.,2020 (69) (Study 1) |
taVNS: 45 Sham: 49 subclinical, high trait worrying sample |
Between Acute taVNS |
Not reported | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 250μs, 30s on 30s off |
Anxiety and fear | GAD | Attentional engagement to threat ↓ |
| Burger et al., 2019 (70) | taVNS: 48 Sham: 49 subclinical, high trait worrying sample |
Between Acute taVNS |
Not reported | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 250μs, 30s ON 30s off |
Anxiety and fear | GAD PTSD |
Negative thought intrusions ↓ |
| Burger et al., 2017 (71) | taVNS: 25 Sham: 26 F: 26 |
Between Acute taVNS |
20-36 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 250μs, 30s on 30s off |
Anxiety and fear | Anxiety PTSD |
Extinction of declarative fear ↑ |
| Burger et al., 2016 (72) | taVNS: 18 Sham: 13 F: 24 |
Between Acute taVNS |
18-25 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 250μs, 30s on 30s off |
Anxiety and fear | Anxiety PTSD |
Extinction learning ↑ |
| Szeska et al., 2020 (73) | 80 (57 F) Fear learning group: taVNS: 20 sham: 20 control group: taVNS: 20 sham: 20 |
Mixed Acute taVNS |
18-34 | taVNS: cymba conchae 2.28(1.13) mA sham: earlobe 2.53(1.11) mA, 25Hz, 200-300μs, 30s on 30s off |
Anxiety and fear | Anxiety PTSD |
Inhibition of fear potentiated startle responses ↑ |
| Jacobs et al., 2015 (74) | 30 (15 F) | Within Acute taVNS |
60.57(2.54) | taVNS: inner tragus sham: earlobe 5.0mA, 8Hz, 200μs |
Anxiety and fear | Anxiety PTSD |
Associated memory performance ↑ |
| Giraudier et al., 2020 (75) | 60 (46 F) | Between Acute taVNS |
23.45(4.87) | taVNS: cymba conchae 1.48(0.59) mA sham: earlobe 1.31(0.50) mA 25Hz, 200-300μs, 30s on 30s off |
Anxiety and fear | Anxiety PTSD |
Recollection-based memory↑ |
| Colzato et al., 2017 (76) | 38 (30 F) | Within Acute taVNS |
18-26 | taVNS: cymba conchae sham: earlobe 0.5mA,25Hz, 200-300μs, 30s on 30s off |
Social dysfunction | ASD ADHD OCD |
Recognition of emotions ↑ |
| Sellaro et al., 2018 (77) | 24 (15 F) | Within Acute taVNS |
18-28 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Social dysfunction | ASD ADHD OCD |
Emotion recognition ↑ |
| Zhu et al., 2022 (78) | 49 (17 F) | Within Acute taVNS |
19.88(1.62) | taVNS: tragus 0.86(0.04) mA sham: earlobe 1.49(0.08) mA 25Hz, 500μs, 30s on 30s off |
Social dysfunction | ASD ADHD OCD |
Visual attention towards social salient facial features ↑
Endogenous oxytocin release ↑ |
| Koenig et al., 2021 (68) | 30 (24 F) healthy controls | Within Acute taVNS |
14-17 | taVNS: concha sham: earlobe 0.5mA, 1Hz, 250μs, 30s on 30s off |
Social dysfunction | ASD ADHD OCD |
Emotion recognition ↑ |
| Villani et al., 2019 (79) | 46 (32 F) | Within Acute taVNS |
21.2(3.1) | taVNS: tragus 1.26(0.23) mA sham: earlobe 1.18(0.18) mA 25Hz, 250μs |
Social dysfunction | Social dysfunction | Interoceptive accuracy ↑ |
| Maraver et al., 2020 (80) | 43 (39 F) | Within Acute taVNS |
18-30 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Social dysfunction | ASD ADHD OCD |
Attention to faces with a direct gaze ↑ |
| Steenbergen et al., 2021 (67) | 73 (58 F) | Within Acute taVNS |
18-28 | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Social dysfunction | ASD ADHD OCD |
Recognition of anger ↑ |
| Ventura-Bort et al., 2021 (81) | 37 (20 F) | Within Acute taVNS |
23.15 | taVNS: cymba conchae 1.34 mA sham: earlobe 1.58 mA 25Hz, 200-300μs |
Social dysfunction | ASD ADHD OCD |
Recollection-based memory for emotional material ↑
Attentional discrimination between emotional and neutral scenes↑ |
| Steenbergen et al., 2015 (82) | 30 (26 F) taVNS: 15 Sham: 15 |
Between Acute taVNS |
18-27 | taVNS: outer auditory canal sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
Responses when two actions were executed in succession ↑ |
| Beste et al., 2016 (83) | 51 (37 F) taVNS: 25 Sham: 26 |
Between Acute taVNS |
23.63 | taVNS: inner ear sham: earlobe 0.5mA, 25Hz 200-300μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
The ability of inhibitory control ↑ |
| Fischer et al., 2018 (84) | 21 (18 F) | Within Acute taVNS |
20.3(1.4) | taVNS: cymba conchae 1.3 mA sham: earlobe 1.49 mA 25Hz, 200-300μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
Adaption to conflict ↑ |
| Jongkees et al., 2018 (85) | 40 (32 F) taVNS: 20 Sham: 20 |
Between Acute taVNS |
taVNS: 22.3(2.7) years Sham: 22.5(2.5) years | taVNS: medial of the tragus sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
Response selection processes ↑ |
| Keute et al., 2019 (86) | 16 (8 F) | Within Acute taVNS |
20-28 | taVNS: cymba conchae 5.9(1.6) mA sham: earlobe 7.5(0.8) mA 25Hz, 200μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
Automatic motor response inhibition ↑ |
| Keute et al., 2020 (87) | 22 (16 F) | Within Acute taVNS |
21-28 | taVNS: cymba conchae 2.37(0.16) mA sham: earlobe 2.6 mA 25Hz, 200μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
General adaptive control and sustained attention ↑ |
| Borges et al., 2020 (88) | 23 (9 F) | Within Acute taVNS |
23.17(4.08) | taVNS: cymba conchae 2.19(0.93) mA sham: earlobe 2.20(1.06) mA 25Hz, 200-300μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
Cognitive flexibility ↑ |
| Pihlaja et al., 2020 (89) | 25 (16 F) | Within Acute taVNS |
25.5(4.8) | aVNS: inner tragus sham: earlobe 30Hz, 250μs |
Impulsivity and inattention | ADHD ASD DBD |
Cognitive control resources required to withhold a prepotent response ↓ |
| Steenbergen et al., 2020 (90) | 84 (52 F) | Within Acute taVNS |
22.32(2.71) | taVNS: cymba conchae sham: earlobe 0.5mA, 25Hz, 200-300μs, 30s on 30s off |
Impulsivity and inattention | ADHD ASD DBD |
Self-control ↑ |
| Llanos et al. 2020 (91) | 36 (20 F) tVNS-hard: 12 tVNS-easy: 12 control: 12 |
Between Acute taVNS |
21.60(3.56) | taVNS: cymba conchae hard: 1.67(0.79) mA easy: 1.24(0.88) mA control: no stimulation |
Others/ Language deficits | ASD | Speech category learning & retention of correct stimulus response associations ↑ |
| Thakkar et al., 2020 (92) | 37 (27 F) Computer control: 7 Device sham control: 7 Earlobe stimulation control: 9 taVNS: 14 |
Between Acute taVNS |
18-28 | taVNS: cymba conchae 1.68(0.87) mA sham control: cymba conchae no stimulation earlobe control: earlobe 1.51(0.35) mA 5Hz, 200μs, 30s on 30s off |
Others/ Language deficits | ASD | Novel orthography acquisition ↑ |
| Hong et al., 2019 (93) | 14 patients requiring open laparotomy (8 F) | Within Acute taVNS |
57.6 (10.5) | taVNS: cymba conchar 10mA, 25Hz, 250μs, Control: no stimulation |
Others/ Gastrointestinal problems | ASD | Stomach function ↑ |
| Teckentrup et al., 2020 (94) | 22 (14 F) | Within Acute taVNS |
19-29 | taVNS: cymba conchae 1.37(0.81) mA sham: earlobe 1.89(0.89) mA 25Hz 30s on 30s off |
Others/ Gastrointestinal problems | ASD | Gastric function ↑ |
| Steidel et al., 2021 (95) | HF taVNS: 24 (15 F) LF taVNS: 28 (18 F) |
Mixed Acute taVNS |
25.5(5.2) | taVNS: cymba conchae, 250μs HF: 25 Hz 0.91(0.43) mA LF: 1 Hz 0.66(0.53) mA 30s on 30s off |
Others/ Gastrointestinal problems | ASD | Gastric function ↑ |
| Wu et al., 2021 (96) | 40 patients with primary insomnia Group A: 20 (15 F) Group B: 20 (13 F) |
Between repeated taVNS (30min of taVNS twice a day, 5 days per week for 4 weeks) |
Group A: 49.40±12.22 years Group B: 46.20±12.76 years |
taVNS: cavum concha 7-12mA, 20Hz, 200μs, No stimulation for Group B (controls) |
Others/ Sleep problems | GAD MDD |
Sleep quality ↑ |
| Zhang et al., 2021 (42) | 20 patients with primary insomnia | Within repeated taVNS (30min of taVNS twice a day, 5 days per week for 4 weeks) |
Not reported | taVNS: cavum concha 0.8-1.5mA, 4/20 Hz, 200μs, |
Others/ Sleep problems | GAD MDD |
Score of Pittsburgh Sleep Quality Index ↓
Sleep duration↑ |
| He et al., 2022 (97) | 24 patients with chronic insomnia (CI) (12F) 18 healthy controls (HC) (12 F) |
Between repeated taVNS for CI patients (30min of taVNS twice a day for 4 weeks), |
CI patients: 42.50±15.42 years HC: 43.5 ± 11.23 years |
taVNS: bilateral cymba conchae 4/20 Hz, 200μs ± 30% No stimulation for HC |
Others/ Sleep problems | GAD MDD |
The scores of Pittsburgh Sleep Quality Index and Flinders Fatigue Scale ↓ |
F, female; HF, high frequency; LF, low frequency. ↑: increased/higher/better. ↓: decreased/lower.