There are six types of brain waves, each with its own frequency, resulting in a particular type of consciousness.
1. Alfa (8-12Hz) waves are connected to a state of relaxation.
2. Beta (16-38Hz) waves aim to deal with stressful situations. The strong feeling of self is the product of beta waves.
3. Theta (4-8Hz) waves occur when you’re in a deeply relaxed state, usually just before you fall asleep or wake up. These waves are also referred to as the creative layer.
4. Delta (0.5-4 Hz) waves occur in babies and during deep sleep.
5. Gamma (30-80 Hz) waves occur during strong mental activity, such as anxiety, problem solving and when you’re in a state of high alert.
6. Sensory-Motor Rhythm (12-16Hz) waves occur during physical rest and strong sensorimotor consciousness.
Effects of psychedelics on brain wave pattern
It’s been shown that recreational use of LSD, psilocybin and ayahuasca causes the alpha and theta brain waves to decline and the beta waves to increase, which strengthens the ego. This contrasts with a ayahuasca ceremony, where the opposite occurs (more alpha and theta, less beta waves) which leads to a reduced sense of self. These different effects have been extensively documented by making an EEG scan of people during the trip; whether a recreational user or used ceremoniously. 
If a completely different brain wave pattern is found, there is also another form of consciousness. Now the question naturally arises how it’s possible that a shamanistic ritual contributes to change in consciousness. The explanation is actually quite simple. The use of psychedelics isn’t the only way to deliberately change our state of consciousness.
The power of meditation
There has been a lot of research into various forms of meditation and the transformation of consciousness. EEG scans were made of people who practised different types of meditation, resulting in different forms of consciousness. 
During a shamanistic ritual a variety of meditation techniques are used, such as staring into a fire, rhythmic song and dance, chanting mantras or just pure silence. In short, a shamanistic ritual with psychedelics affects consciousness in two ways, namely by the administration of psychedelics and through undergoing meditation techniques.
Apparently this combination leads to a completely different form of consciousness than if you just make use of psychedelics. For that reason, some people hold the believe that the experience and therefore value of a shamanistic ritual is not comparable to tripping without any form of meditation accompanying it.
At the same time, it’s of course interesting to realize that we can influence our psychedelic trip by meditating. For that reason, the Azarius encyclopaedia now has an extensive chapter on meditation. If you want to start meditating, it’s prudent to realize that meditation is not always without risk. The article in the encyclopaedia will expand on this.
1. Erik Hoffmann, Effects of a Psychedelic, Tropical Tea, Ayahuasca, on the Electroencephalographic (EEG) Activity of the Human Brain During a Shamanistic Ritual.
2. J.P Banquet, Spectral analysis of the EEG in meditation, Electroencephalography and Clinical Neurophysiology, Volume 35, Issue 2, August 1973, Pages 143–151.
3. H.-Y. Huang1† , P.-C. Lo1, EEG dynamics of experienced Zen meditation practitioners probed by complexity index and spectral measure, 2009, Vol. 33, No. 4 , Pages 314-321.
4. L.I. Aftanas,, S.A. Golocheikine, Human anterior and frontal midline theta and lower alpha reflect emotionally positive state and internalized attention: high-resolution EEG investigation of meditation Neuroscience Letters, Volume 310, Issue 1, 7 September 2001, Pages 57–60.
5. Tetsuya Takahashia, Tetsuhito Murataa,Toshihiko Hamadab, Masao Omoria, Hirotaka Kosakaa, Mitsuru Kikuchic, Haruyoshi Yoshidab, Yuji Wadaa Changes in EEG and autonomic nervous activity during meditation and their association with personality trait, International Journal of Psychophysiology Volume 55, Issue 2, February 2005, Pages 199–207.