Table 11.
A summary of selected human and animal studies. The number of studies was counted for each IGF estimation modality, specific tasks within the modalities and the factors related to IGF. In addition, the IGF range within each modality is presented. Factors related to IGF include only those studies that found a statistically significant relationship.
| Human Studies | ||||
|---|---|---|---|---|
| IGF Estimation Modality | Number of Studies | Stimuli and Tasks Used for IGF Estimation | IGF Range | Factors Related to IGF |
| Resting-state | 2 | - | 30–43 Hz | Neuropsychiatric disorders: 1 Age: 2 |
| Visual | 39 | Visual gratings: 37 Visual checkerboard stimulus: 1 Visual plaids: 1 Visual grid stimulus: 1 |
35–100 Hz | Anatomical: 7 Neurochemical: 7 Neuropsychiatric disorders: 2 Brain states: 1 Age: 8 Visual processing: 15 |
| Auditory | 17 | Auditory steady-state stimulation: 14 Auditory stimulation with changing intensity: 2 Auditory sensory-gating stimulation: 1 Auditory oddball stimulation: 1 |
28–63 Hz * | Neuropsychiatric disorders: 4 Brain states: 4 Age: 4 Auditory processing: 4 Cognitive processing: 5 |
| Somatosensory | 5 | Electrical stimulation of the wrist: 3 Somatosensory Go–Nogo task: 1 Proprioceptive stimulation: 1 |
25–90 Hz | Anatomical: 1 Neuropsychiatric disorders: 1 Somatosensory processing: 3 |
| Motor | 6 | Finger/palm muscle contractions: 3 Arm movements: 1 Foot movements: 1 Block movement task: 1 Button press: 1 Manual tracking task: 1 |
63–85 Hz | Neurochemical: 1 Age: 1 Motor activity: 2 Cognitive processing: 1 |
| Cognitive | 8 | Working memory tasks: 3 Categorization task: 1 Perceptual rivalry task: 1 Response inhibition task: 1 Selective attention task: 1 Musical performance tasks: 1 |
40–100 Hz | Neurochemical: 4 Age: 1 Visual processing: 1 Cognitive processing: 4 |
| In Vivo Animal Studies | ||||
| IGF Estimation Modality | Number of Studies | Stimuli and Tasks Used for IGF Estimation | IGF Range | Factors Related to IGF |
| Visual | 11 | Visual gratings: 10 Natural images: 2 Visual plaids: 1 Visual illusory stimuli: 1 |
30–80 Hz | Anatomical: 1 Brain states: 1 Visual processing: 9 Cognitive processing: 1 |
| Motor | 3 | Free movement: 2 Motor tasks: 1 |
30–100 Hz | Neurochemical: 2 Motor activity: 1 |
| Cognitive | 3 | Decision-making tasks: 1 Visual attention task: 1 Surface food test: 1 Novel object recognition test: 1 |
40–60 Hz | Brain states: 1 Age: 1 Visual processing: 1 |
Abbreviation: IGF—individual gamma frequency. * Wyss et al. [24] reported the IGF range extracted from auditory stimulation to be between 30 and 160 Hz; however, in the other studies, the highest IGF values were up to around 63 Hz.