Table 1. Concept map.

Concept	MeSH	Emtree	Thesaurus	Free text
Electroencephalography	Electroencephalography	Electroencephalography	Electroencephalography	electroencephalography, electroencephalographies, EEG, eeg, brain electrical activity, electric encephalogram, electro encephalogram, electroencephalogram, brain wave, biofeedback, neurofeedback, neurobiofeedback
Brain-computer interface	Brain-Computer Interfaces	Noninvasive brain-Computer interface	Nonea	BCI, Brain-machine interface, Brain-machine interface, direct neural interface, noninvasive brain-computer interface, noninvasive brain computer interface
Vibration	Vibration	Vibration	Vibration	vibration, vibrational, vibrotactile, vibrations, vibrate, vibrated, vibrates, vibrating, vibrator, vibrators, vibration sense, tactual, sense of touch, touch stimulus, tactility, tactile stimulation, tactile, touch, haptic

^aNone: No indexed term for the concept