Table 2.

List of EEG NFB studies

First author	Training	Control	Assessment	Training sessions and duration	Sample size and characteristics (male/female; training/control)	Occupation/condition	Age of subjects	Results
Bazanova et al. (2013)	Increased alpha activity at Pz with right ear as reference	Sham	Psychometric tests, HRV, EMG	10 sessions	27 (14 male)	ND	18–34 years	Individual NFB alpha training effectively altered HRV, providing predictive value. Subjects with low baseline alpha power exhibited a positive correlation between alpha peak frequency and pNN50, while a negative correlation was observed in subjects with high baseline alpha power. Increased accuracy and control of cognitive performance, decreased anxiety and frontal EMG activity, and enhanced resting frequency was caused by alpha training. Alpha training also abolished a decline in alpha power in response to an arithmetic task even after 1 month
Durousseau (2013)	Z-score NFB	ND	Neuropsychological assessment, plasma cortisol from one subject	20	2	Military specialists		NFB-related Z-score changes in brain waves towards normative patterns, and reduction in anxiety and stress. Improvement in management of daily behaviors
Gilroy et al. (2013)	Alpha asymmetry at F3-F4		fMRI	2 NFB windows of 30 s during an active session of 8 min	15 (12 male),	ND	29.38 ± 7.6	Prefrontal alpha asymmetry NFB training increased empathic support responses. MRI scans revealed activation in associated brain regions during the expression of support
Kotozaki et al. (2014)	1chNIRS at frontopolar cortex (double blind)	Sham	MRI, psychological measures and salivary cortisol	4 weeks of daily 30-min training sessions	30 males; 15 controls	ND	23–53	Intervention group exhibited significant improvement in psychological test scores and reduced salivary cortisol levels. Findings indicate that BFT is effective for protecting GM structures from the effects of stress
Burns (2015)	Increased SMR, decreased theta, decreased high beta at T4-P4	None	Psychometric assessment (SCL-90-R and QOLI), cortisol and DHEAS	20–30-min sessions	1 female	HAE	43	The results suggest a reduction of emotional, mental, and physical triggers of stress. NFB training led to reduced cortisol levels, reduced cortisol-DHEA-S ratio, decreased use of acute medication, reduced activity on all average brainwave measures (delta, theta, beta, alpha and SMR) and improved quality of life assessment scores
Brühl et al. (2014)	RT-FMRI-NFB in amygdala	None		4 sessions	6 (2 male)	ND	26 ± 3.8	The results support the use of RT-fMRI-NFB training for regulating brain activity during negative emotional stimulation, and have implications for clinical treatment of emotional disorders

HAE: Hereditary Angioedema; ND: not described; SCL-90-R: symptom checklist-90-R; QOLI: quality of life inventory; DHEA: dehydroepiandrosterone-sulfate