Biofeedback is a Connection Technique that uses biofeedback to facilitate "certain specific frequencies of brainwaves." 
List of Connection Techniques
Connection Technique > Affirmation, Autogenic Training, Biofeedback, Bornless Ritual, Breathing, Caloric Reduction, Cocooning, Connection Affirmation, Connection Visualization, Dance, Deprivation, Detachment, Drumming, Fasting, Flow Control, Flow Purification, Graduation Invocation, Holotropic Breathwork, Hypoventilation, Intent, Intent to Connect, Japam, Mantra, Meditation, Mindfulness, Mysticism of the Historical Event, Poetry, Power Quest, Receptive Seeking, Relaxation, Sensory Deprivation, Spirit Canoe, The Method of the Lamp, The Way of the Hollow Bone, Thought Control, Vajra Breath, Vision Quest, Visualization, Writing, Zazen
As Grof notes, Another well-known laboratory method of changing consciousness is biofeedback, where the individual is guided by electronic feedback signals into holotropic states of consciousness characterized by preponderance of certain specific frequencies of brainwaves. We could also mention here the techniques of sleep and dream deprivation and lucid dreaming."