Mikey Sklar wrote a blog for Adafruit about the effect of yogic breathing on brainwaves:

https://blog.adafruit.com/2019/06/10/biohacking-the-positive-effects-of-yogic-breathing/

Investigations by the group of Richard Davidson, professor of Psychology and Psychiatry at the University of Wisconsin–Madison and founder and director of the Center for Healthy Minds have shown that practicing meditation leads to a rise of gamma wave oscillations in the prefrontal cortex:

https://www.pnas.org/content/101/46/16369

The rise of gamma waves is associated with a specific insight of the person who is under investigation, and lasts significantly longer in meditators than in non-meditators.

Further information:

Altered Traits: Science Reveals How Meditation Changes Your Mind, Brain, and Body

Daniel Goleman , Richard J. Davidson

Richard Davidson, Founder of the Center for Healthy Minds