TABLE 3.
Spectral processing.
| References | Population | Paradigm | Stimulation type | Active electrode | Reference electrode | Stimulation parameters | Acquisition | Results |
| Mathys et al. (2010) | Adults (Mage = 25.9) n = 26 | Pitch direction discrimination task | a-tDCS c-tDCS | 16.3 cm2 C3–T3 C4–T4 O1–O2 (control) | 30 cm2 Contralateral supraorbital region | 2 mA 0.1 mA/cm2 25 min | Offline | c-tDCS over the left and right AC reduced pitch discrimination |
|
Tang and Hammond (2013) Experiment 1 |
Adults (age: 18–27) n = 15 | Frequency discrimination | a-tDCS Sham | 24 cm2 C4–T4 | 24 cm2 Contralateral supraorbital region | 1 mA 0.04 mA/cm2 20 min | Online | a-tDCS over right AC temporarily impaired frequency discrimination (< 24 h) |
|
Tang and Hammond (2013) Experiment 2A |
Adults (age: 18–27) n = 7 | Frequency selectivity | a-tDCS Sham | 24 cm2 C4–T4 | 24 cm2 Contralateral supraorbital region | 1 mA 0.04 mA/cm2 20 min | Online | a-tDCS reduced frequency selectivity |
|
Tang and Hammond (2013) Experiment 2B |
Adults (age: 18–27) n = 6 | Frequency discrimination; Temporal fine structure (TFS) | a-tDCS Sham | 24 cm2 C4–T4 | 24 cm2 Contralateral supraorbital region | 1 mA 0.04 mA/cm2 20 min | Online | a-tDCS decreased frequency discrimination by disrupting temporal coding |
| Matsushita et al. (2015) | Adults (Mage = 22.2) n = 42 | Pitch discrimination task | a-tDCS c-tDCS Sham | 35 cm2 Right Heschl’s gyri (HG) | 35 cm2 Above left eyebrow | 1 mA 0.03 mA/cm2 20 min | Online and Offline | a-tDCS impaired auditory pitch learning |
| Loui et al. (2010) | Adults (Mage = 25.3) n = 9 | Pitch perception Pitch matching Pitch production | c-tDCS Sham | 16 cm2 TP7–C5 (STG) TP8–C6 (STG) F7–C5 (IFG) F8–C6 (IFG) | 16 cm2 Contralateral supraorbital region | 2 mA mA/cm2 20 min | Offline | c-tDCS over right STG and left IFG reduced accuracy in pitch matching |
STG, Superior temporal gyrus; IFG, Inferior frontal gyrus.