Table 7.

Selected studies that reported IGF’s relationship with auditory processing.

Author and Year	Sample	Methods	IGF Measure	Relevant Findings
Purcell et al., 2004 [31]	38 healthy adults	EEG, auditory steady-state stimulation, gap detection task	Amplitude	IGF in young (18–43): 41 ± 5 Hz; IGF in old (60–78): 37 ± 4 Hz. Positive correlation of IGF with frequency modulation detection (r = 0.72), negative correlation with gap detection latency (r = −0.43)
Baltus and Herrmann 2015 [41]	35 healthy adults	EEG, auditory steady-state stimulation, gap detection task	Amplitude	IGF: 46.5 ± 6.38 Hz. Negative correlation of IGF with gap detection threshold (r = −0.46)
Baltus et al., 2020 [83]	16 healthy adults	EEG, tACS, auditory steady-state stimulation, gap detection task	Amplitude	IGF: ~35–60 Hz. Negative correlation of IGF with gap detection threshold (rho = −0.6). Positive correlation of IGF with change in performance after tACS in the experimental group (rho = 0.81), but not in the control group
da Silva et al., 2021 [109]	31 healthy children: 16 with musical training, 15 without musical training	EEG, motor and music-related tasks	Power	Over F3-F4 channels, IGF in musically trained: 35 Hz; IGF in musically untrained: 33 Hz

Abbreviations: EEG—electroencephalogram; IGF—individual gamma frequency; tACS—transcranial alternating current stimulation.